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android / platform / external / mdnsresponder / refs/tags/android-p-preview-2 / . / mDNSCore / DNSCommon.c
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/* -*- Mode: C; tab-width: 4 -*-
*
* Copyright (c) 2002-2003 Apple Computer, Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Set mDNS_InstantiateInlines to tell mDNSEmbeddedAPI.h to instantiate inline functions, if necessary
#define mDNS_InstantiateInlines 1
#include "DNSCommon.h"
// Disable certain benign warnings with Microsoft compilers
#if (defined(_MSC_VER))
// Disable "conditional expression is constant" warning for debug macros.
// Otherwise, this generates warnings for the perfectly natural construct "while(1)"
// If someone knows a variant way of writing "while(1)" that doesn't generate warning messages, please let us know
#pragma warning(disable:4127)
// Disable "array is too small to include a terminating null character" warning
// -- domain labels have an initial length byte, not a terminating null character
#pragma warning(disable:4295)
#endif
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark - Program Constants
#endif
mDNSexport const mDNSInterfaceID mDNSInterface_Any = 0;
mDNSexport const mDNSInterfaceID mDNSInterfaceMark = (mDNSInterfaceID)-1;
mDNSexport const mDNSInterfaceID mDNSInterface_LocalOnly = (mDNSInterfaceID)-2;
mDNSexport const mDNSInterfaceID mDNSInterface_Unicast = (mDNSInterfaceID)-3;
mDNSexport const mDNSInterfaceID mDNSInterface_P2P = (mDNSInterfaceID)-4;
// Note: Microsoft's proposed "Link Local Multicast Name Resolution Protocol" (LLMNR) is essentially a limited version of
// Multicast DNS, using the same packet formats, naming syntax, and record types as Multicast DNS, but on a different UDP
// port and multicast address, which means it won't interoperate with the existing installed base of Multicast DNS responders.
// LLMNR uses IPv4 multicast address 224.0.0.252, IPv6 multicast address FF02::0001:0003, and UDP port 5355.
// Uncomment the appropriate lines below to build a special Multicast DNS responder for testing interoperability
// with Microsoft's LLMNR client code.
#define DiscardPortAsNumber 9
#define SSHPortAsNumber 22
#define UnicastDNSPortAsNumber 53
#define SSDPPortAsNumber 1900
#define IPSECPortAsNumber 4500
#define NSIPCPortAsNumber 5030 // Port used for dnsextd to talk to local nameserver bound to loopback
#define NATPMPAnnouncementPortAsNumber 5350
#define NATPMPPortAsNumber 5351
#define DNSEXTPortAsNumber 5352 // Port used for end-to-end DNS operations like LLQ, Updates with Leases, etc.
#define MulticastDNSPortAsNumber 5353
#define LoopbackIPCPortAsNumber 5354
//#define MulticastDNSPortAsNumber 5355 // LLMNR
#define PrivateDNSPortAsNumber 5533
mDNSexport const mDNSIPPort DiscardPort = { { DiscardPortAsNumber >> 8, DiscardPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort SSHPort = { { SSHPortAsNumber >> 8, SSHPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort UnicastDNSPort = { { UnicastDNSPortAsNumber >> 8, UnicastDNSPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort SSDPPort = { { SSDPPortAsNumber >> 8, SSDPPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort IPSECPort = { { IPSECPortAsNumber >> 8, IPSECPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort NSIPCPort = { { NSIPCPortAsNumber >> 8, NSIPCPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort NATPMPAnnouncementPort = { { NATPMPAnnouncementPortAsNumber >> 8, NATPMPAnnouncementPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort NATPMPPort = { { NATPMPPortAsNumber >> 8, NATPMPPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort DNSEXTPort = { { DNSEXTPortAsNumber >> 8, DNSEXTPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort MulticastDNSPort = { { MulticastDNSPortAsNumber >> 8, MulticastDNSPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort LoopbackIPCPort = { { LoopbackIPCPortAsNumber >> 8, LoopbackIPCPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort PrivateDNSPort = { { PrivateDNSPortAsNumber >> 8, PrivateDNSPortAsNumber & 0xFF } };
mDNSexport const OwnerOptData zeroOwner = { 0, 0, { { 0 } }, { { 0 } }, { { 0 } } };
mDNSexport const mDNSIPPort zeroIPPort = { { 0 } };
mDNSexport const mDNSv4Addr zerov4Addr = { { 0 } };
mDNSexport const mDNSv6Addr zerov6Addr = { { 0 } };
mDNSexport const mDNSEthAddr zeroEthAddr = { { 0 } };
mDNSexport const mDNSv4Addr onesIPv4Addr = { { 255, 255, 255, 255 } };
mDNSexport const mDNSv6Addr onesIPv6Addr = { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 } };
mDNSexport const mDNSEthAddr onesEthAddr = { { 255, 255, 255, 255, 255, 255 } };
mDNSexport const mDNSAddr zeroAddr = { mDNSAddrType_None, {{{ 0 }}} };
mDNSexport const mDNSv4Addr AllDNSAdminGroup = { { 239, 255, 255, 251 } };
mDNSexport const mDNSv4Addr AllHosts_v4 = { { 224, 0, 0, 1 } }; // For NAT-PMP Annoucements
mDNSexport const mDNSv6Addr AllHosts_v6 = { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x01 } };
mDNSexport const mDNSv6Addr NDP_prefix = { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x01, 0xFF,0x00,0x00,0xFB } }; // FF02:0:0:0:0:1:FF00::/104
mDNSexport const mDNSEthAddr AllHosts_v6_Eth = { { 0x33, 0x33, 0x00, 0x00, 0x00, 0x01 } };
mDNSexport const mDNSAddr AllDNSLinkGroup_v4 = { mDNSAddrType_IPv4, { { { 224, 0, 0, 251 } } } };
//mDNSexport const mDNSAddr AllDNSLinkGroup_v4 = { mDNSAddrType_IPv4, { { { 224, 0, 0, 252 } } } }; // LLMNR
mDNSexport const mDNSAddr AllDNSLinkGroup_v6 = { mDNSAddrType_IPv6, { { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0xFB } } } };
//mDNSexport const mDNSAddr AllDNSLinkGroup_v6 = { mDNSAddrType_IPv6, { { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x01,0x00,0x03 } } } }; // LLMNR
mDNSexport const mDNSOpaque16 zeroID = { { 0, 0 } };
mDNSexport const mDNSOpaque16 onesID = { { 255, 255 } };
mDNSexport const mDNSOpaque16 QueryFlags = { { kDNSFlag0_QR_Query | kDNSFlag0_OP_StdQuery, 0 } };
mDNSexport const mDNSOpaque16 uQueryFlags = { { kDNSFlag0_QR_Query | kDNSFlag0_OP_StdQuery | kDNSFlag0_RD, 0 } };
mDNSexport const mDNSOpaque16 ResponseFlags = { { kDNSFlag0_QR_Response | kDNSFlag0_OP_StdQuery | kDNSFlag0_AA, 0 } };
mDNSexport const mDNSOpaque16 UpdateReqFlags = { { kDNSFlag0_QR_Query | kDNSFlag0_OP_Update, 0 } };
mDNSexport const mDNSOpaque16 UpdateRespFlags = { { kDNSFlag0_QR_Response | kDNSFlag0_OP_Update, 0 } };
mDNSexport const mDNSOpaque64 zeroOpaque64 = { { 0 } };
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - General Utility Functions
#endif
// return true for RFC1918 private addresses
mDNSexport mDNSBool mDNSv4AddrIsRFC1918(mDNSv4Addr *addr)
{
return ((addr->b[0] == 10) || // 10/8 prefix
(addr->b[0] == 172 && (addr->b[1] & 0xF0) == 16) || // 172.16/12
(addr->b[0] == 192 && addr->b[1] == 168)); // 192.168/16
}
mDNSexport NetworkInterfaceInfo *GetFirstActiveInterface(NetworkInterfaceInfo *intf)
{
while (intf && !intf->InterfaceActive) intf = intf->next;
return(intf);
}
mDNSexport mDNSInterfaceID GetNextActiveInterfaceID(const NetworkInterfaceInfo *intf)
{
const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next);
if (next) return(next->InterfaceID); else return(mDNSNULL);
}
mDNSexport mDNSu32 NumCacheRecordsForInterfaceID(const mDNS *const m, mDNSInterfaceID id)
{
mDNSu32 slot, used = 0;
CacheGroup *cg;
const CacheRecord *rr;
FORALL_CACHERECORDS(slot, cg, rr)
if (rr->resrec.InterfaceID == id) used++;
return(used);
}
mDNSexport char *DNSTypeName(mDNSu16 rrtype)
{
switch (rrtype)
{
case kDNSType_A: return("Addr");
case kDNSType_NS: return("NS");
case kDNSType_CNAME:return("CNAME");
case kDNSType_SOA: return("SOA");
case kDNSType_NULL: return("NULL");
case kDNSType_PTR: return("PTR");
case kDNSType_HINFO:return("HINFO");
case kDNSType_TXT: return("TXT");
case kDNSType_AAAA: return("AAAA");
case kDNSType_SRV: return("SRV");
case kDNSType_OPT: return("OPT");
case kDNSType_NSEC: return("NSEC");
case kDNSType_TSIG: return("TSIG");
case kDNSQType_ANY: return("ANY");
default: {
static char buffer[16];
mDNS_snprintf(buffer, sizeof(buffer), "(%d)", rrtype);
return(buffer);
}
}
}
// Note slight bug: this code uses the rdlength from the ResourceRecord object, to display
// the rdata from the RDataBody object. Sometimes this could be the wrong length -- but as
// long as this routine is only used for debugging messages, it probably isn't a big problem.
mDNSexport char *GetRRDisplayString_rdb(const ResourceRecord *const rr, const RDataBody *const rd1, char *const buffer)
{
const RDataBody2 *const rd = (RDataBody2 *)rd1;
#define RemSpc (MaxMsg-1-length)
char *ptr = buffer;
mDNSu32 length = mDNS_snprintf(buffer, MaxMsg-1, "%4d %##s %s ", rr->rdlength, rr->name->c, DNSTypeName(rr->rrtype));
if (rr->RecordType == kDNSRecordTypePacketNegative) return(buffer);
if (!rr->rdlength) { mDNS_snprintf(buffer+length, RemSpc, "<< ZERO RDATA LENGTH >>"); return(buffer); }
switch (rr->rrtype)
{
case kDNSType_A: mDNS_snprintf(buffer+length, RemSpc, "%.4a", &rd->ipv4); break;
case kDNSType_NS: // Same as PTR
case kDNSType_CNAME:// Same as PTR
case kDNSType_PTR: mDNS_snprintf(buffer+length, RemSpc, "%##s", rd->name.c); break;
case kDNSType_SOA: mDNS_snprintf(buffer+length, RemSpc, "%##s %##s %d %d %d %d %d",
rd->soa.mname.c, rd->soa.rname.c,
rd->soa.serial, rd->soa.refresh, rd->soa.retry, rd->soa.expire, rd->soa.min);
break;
case kDNSType_HINFO:// Display this the same as TXT (show all constituent strings)
case kDNSType_TXT: {
const mDNSu8 *t = rd->txt.c;
while (t < rd->txt.c + rr->rdlength)
{
length += mDNS_snprintf(buffer+length, RemSpc, "%s%#s", t > rd->txt.c ? "¦" : "", t);
t += 1 + t[0];
}
} break;
case kDNSType_AAAA: mDNS_snprintf(buffer+length, RemSpc, "%.16a", &rd->ipv6); break;
case kDNSType_SRV: mDNS_snprintf(buffer+length, RemSpc, "%u %u %u %##s",
rd->srv.priority, rd->srv.weight, mDNSVal16(rd->srv.port), rd->srv.target.c); break;
case kDNSType_OPT: {
const rdataOPT *opt;
const rdataOPT *const end = (const rdataOPT *)&rd->data[rr->rdlength];
length += mDNS_snprintf(buffer+length, RemSpc, "Max %d", rr->rrclass);
for (opt = &rd->opt[0]; opt < end; opt++)
{
switch(opt->opt)
{
case kDNSOpt_LLQ:
length += mDNS_snprintf(buffer+length, RemSpc, " Vers %d", opt->u.llq.vers);
length += mDNS_snprintf(buffer+length, RemSpc, " Op %d", opt->u.llq.llqOp);
length += mDNS_snprintf(buffer+length, RemSpc, " Err/Port %d", opt->u.llq.err);
length += mDNS_snprintf(buffer+length, RemSpc, " ID %08X%08X", opt->u.llq.id.l[0], opt->u.llq.id.l[1]);
length += mDNS_snprintf(buffer+length, RemSpc, " Lease %d", opt->u.llq.llqlease);
break;
case kDNSOpt_Lease:
length += mDNS_snprintf(buffer+length, RemSpc, " Lease %d", opt->u.updatelease);
break;
case kDNSOpt_Owner:
length += mDNS_snprintf(buffer+length, RemSpc, " Vers %d", opt->u.owner.vers);
length += mDNS_snprintf(buffer+length, RemSpc, " Seq %3d", (mDNSu8)opt->u.owner.seq); // Display as unsigned
length += mDNS_snprintf(buffer+length, RemSpc, " MAC %.6a", opt->u.owner.HMAC.b);
if (opt->optlen >= DNSOpt_OwnerData_ID_Wake_Space-4)
{
length += mDNS_snprintf(buffer+length, RemSpc, " I-MAC %.6a", opt->u.owner.IMAC.b);
if (opt->optlen > DNSOpt_OwnerData_ID_Wake_Space-4)
length += mDNS_snprintf(buffer+length, RemSpc, " Password %.6a", opt->u.owner.password.b);
}
break;
default:
length += mDNS_snprintf(buffer+length, RemSpc, " Unknown %d", opt->opt);
break;
}
}
}
break;
case kDNSType_NSEC: {
mDNSu16 i;
for (i=0; i<255; i++)
if (rd->nsec.bitmap[i>>3] & (128 >> (i&7)))
length += mDNS_snprintf(buffer+length, RemSpc, "%s ", DNSTypeName(i));
}
break;
default: mDNS_snprintf(buffer+length, RemSpc, "RDLen %d: %s", rr->rdlength, rd->data);
// Really should scan buffer to check if text is valid UTF-8 and only replace with dots if not
for (ptr = buffer; *ptr; ptr++) if (*ptr < ' ') *ptr = '.';
break;
}
return(buffer);
}
// See comments in mDNSEmbeddedAPI.h
#if _PLATFORM_HAS_STRONG_PRNG_
#define mDNSRandomNumber mDNSPlatformRandomNumber
#else
mDNSlocal mDNSu32 mDNSRandomFromSeed(mDNSu32 seed)
{
return seed * 21 + 1;
}
mDNSlocal mDNSu32 mDNSMixRandomSeed(mDNSu32 seed, mDNSu8 iteration)
{
return iteration ? mDNSMixRandomSeed(mDNSRandomFromSeed(seed), --iteration) : seed;
}
mDNSlocal mDNSu32 mDNSRandomNumber()
{
static mDNSBool seeded = mDNSfalse;
static mDNSu32 seed = 0;
if (!seeded)
{
seed = mDNSMixRandomSeed(mDNSPlatformRandomSeed(), 100);
seeded = mDNStrue;
}
return (seed = mDNSRandomFromSeed(seed));
}
#endif // ! _PLATFORM_HAS_STRONG_PRNG_
mDNSexport mDNSu32 mDNSRandom(mDNSu32 max) // Returns pseudo-random result from zero to max inclusive
{
mDNSu32 ret = 0;
mDNSu32 mask = 1;
while (mask < max) mask = (mask << 1) | 1;
do ret = mDNSRandomNumber() & mask;
while (ret > max);
return ret;
}
mDNSexport mDNSBool mDNSSameAddress(const mDNSAddr *ip1, const mDNSAddr *ip2)
{
if (ip1->type == ip2->type)
{
switch (ip1->type)
{
case mDNSAddrType_None : return(mDNStrue); // Empty addresses have no data and are therefore always equal
case mDNSAddrType_IPv4 : return(mDNSBool)(mDNSSameIPv4Address(ip1->ip.v4, ip2->ip.v4));
case mDNSAddrType_IPv6 : return(mDNSBool)(mDNSSameIPv6Address(ip1->ip.v6, ip2->ip.v6));
}
}
return(mDNSfalse);
}
mDNSexport mDNSBool mDNSAddrIsDNSMulticast(const mDNSAddr *ip)
{
switch(ip->type)
{
case mDNSAddrType_IPv4: return(mDNSBool)(mDNSSameIPv4Address(ip->ip.v4, AllDNSLinkGroup_v4.ip.v4));
case mDNSAddrType_IPv6: return(mDNSBool)(mDNSSameIPv6Address(ip->ip.v6, AllDNSLinkGroup_v6.ip.v6));
default: return(mDNSfalse);
}
}
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Domain Name Utility Functions
#endif
mDNSexport mDNSBool SameDomainLabel(const mDNSu8 *a, const mDNSu8 *b)
{
int i;
const int len = *a++;
if (len > MAX_DOMAIN_LABEL)
{ debugf("Malformed label (too long)"); return(mDNSfalse); }
if (len != *b++) return(mDNSfalse);
for (i=0; i<len; i++)
{
mDNSu8 ac = *a++;
mDNSu8 bc = *b++;
if (mDNSIsUpperCase(ac)) ac += 'a' - 'A';
if (mDNSIsUpperCase(bc)) bc += 'a' - 'A';
if (ac != bc) return(mDNSfalse);
}
return(mDNStrue);
}
mDNSexport mDNSBool SameDomainName(const domainname *const d1, const domainname *const d2)
{
const mDNSu8 * a = d1->c;
const mDNSu8 * b = d2->c;
const mDNSu8 *const max = d1->c + MAX_DOMAIN_NAME; // Maximum that's valid
while (*a || *b)
{
if (a + 1 + *a >= max)
{ debugf("Malformed domain name (more than 256 characters)"); return(mDNSfalse); }
if (!SameDomainLabel(a, b)) return(mDNSfalse);
a += 1 + *a;
b += 1 + *b;
}
return(mDNStrue);
}
mDNSexport mDNSBool SameDomainNameCS(const domainname *const d1, const domainname *const d2)
{
mDNSu16 l1 = DomainNameLength(d1);
mDNSu16 l2 = DomainNameLength(d2);
return(l1 <= MAX_DOMAIN_NAME && l1 == l2 && mDNSPlatformMemSame(d1, d2, l1));
}
mDNSexport mDNSBool IsLocalDomain(const domainname *d)
{
// Domains that are defined to be resolved via link-local multicast are:
// local., 254.169.in-addr.arpa., and {8,9,A,B}.E.F.ip6.arpa.
static const domainname *nL = (const domainname*)"\x5" "local";
static const domainname *nR = (const domainname*)"\x3" "254" "\x3" "169" "\x7" "in-addr" "\x4" "arpa";
static const domainname *n8 = (const domainname*)"\x1" "8" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
static const domainname *n9 = (const domainname*)"\x1" "9" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
static const domainname *nA = (const domainname*)"\x1" "a" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
static const domainname *nB = (const domainname*)"\x1" "b" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
const domainname *d1, *d2, *d3, *d4, *d5; // Top-level domain, second-level domain, etc.
d1 = d2 = d3 = d4 = d5 = mDNSNULL;
while (d->c[0])
{
d5 = d4; d4 = d3; d3 = d2; d2 = d1; d1 = d;
d = (const domainname*)(d->c + 1 + d->c[0]);
}
if (d1 && SameDomainName(d1, nL)) return(mDNStrue);
if (d4 && SameDomainName(d4, nR)) return(mDNStrue);
if (d5 && SameDomainName(d5, n8)) return(mDNStrue);
if (d5 && SameDomainName(d5, n9)) return(mDNStrue);
if (d5 && SameDomainName(d5, nA)) return(mDNStrue);
if (d5 && SameDomainName(d5, nB)) return(mDNStrue);
return(mDNSfalse);
}
mDNSexport const mDNSu8 *LastLabel(const domainname *d)
{
const mDNSu8 *p = d->c;
while (d->c[0])
{
p = d->c;
d = (const domainname*)(d->c + 1 + d->c[0]);
}
return(p);
}
// Returns length of a domain name INCLUDING the byte for the final null label
// e.g. for the root label "." it returns one
// For the FQDN "com." it returns 5 (length byte, three data bytes, final zero)
// Legal results are 1 (just root label) to 256 (MAX_DOMAIN_NAME)
// If the given domainname is invalid, result is 257 (MAX_DOMAIN_NAME+1)
mDNSexport mDNSu16 DomainNameLengthLimit(const domainname *const name, const mDNSu8 *limit)
{
const mDNSu8 *src = name->c;
while (src < limit && *src <= MAX_DOMAIN_LABEL)
{
if (*src == 0) return((mDNSu16)(src - name->c + 1));
src += 1 + *src;
}
return(MAX_DOMAIN_NAME+1);
}
// CompressedDomainNameLength returns the length of a domain name INCLUDING the byte
// for the final null label, e.g. for the root label "." it returns one.
// E.g. for the FQDN "foo.com." it returns 9
// (length, three data bytes, length, three more data bytes, final zero).
// In the case where a parent domain name is provided, and the given name is a child
// of that parent, CompressedDomainNameLength returns the length of the prefix portion
// of the child name, plus TWO bytes for the compression pointer.
// E.g. for the name "foo.com." with parent "com.", it returns 6
// (length, three data bytes, two-byte compression pointer).
mDNSexport mDNSu16 CompressedDomainNameLength(const domainname *const name, const domainname *parent)
{
const mDNSu8 *src = name->c;
if (parent && parent->c[0] == 0) parent = mDNSNULL;
while (*src)
{
if (*src > MAX_DOMAIN_LABEL) return(MAX_DOMAIN_NAME+1);
if (parent && SameDomainName((const domainname *)src, parent)) return((mDNSu16)(src - name->c + 2));
src += 1 + *src;
if (src - name->c >= MAX_DOMAIN_NAME) return(MAX_DOMAIN_NAME+1);
}
return((mDNSu16)(src - name->c + 1));
}
// CountLabels() returns number of labels in name, excluding final root label
// (e.g. for "apple.com." CountLabels returns 2.)
mDNSexport int CountLabels(const domainname *d)
{
int count = 0;
const mDNSu8 *ptr;
for (ptr = d->c; *ptr; ptr = ptr + ptr[0] + 1) count++;
return count;
}
// SkipLeadingLabels skips over the first 'skip' labels in the domainname,
// returning a pointer to the suffix with 'skip' labels removed.
mDNSexport const domainname *SkipLeadingLabels(const domainname *d, int skip)
{
while (skip > 0 && d->c[0]) { d = (const domainname *)(d->c + 1 + d->c[0]); skip--; }
return(d);
}
// AppendLiteralLabelString appends a single label to an existing (possibly empty) domainname.
// The C string contains the label as-is, with no escaping, etc.
// Any dots in the name are literal dots, not label separators
// If successful, AppendLiteralLabelString returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// AppendLiteralLabelString returns mDNSNULL.
mDNSexport mDNSu8 *AppendLiteralLabelString(domainname *const name, const char *cstr)
{
mDNSu8 * ptr = name->c + DomainNameLength(name) - 1; // Find end of current name
const mDNSu8 *const lim1 = name->c + MAX_DOMAIN_NAME - 1; // Limit of how much we can add (not counting final zero)
const mDNSu8 *const lim2 = ptr + 1 + MAX_DOMAIN_LABEL;
const mDNSu8 *const lim = (lim1 < lim2) ? lim1 : lim2;
mDNSu8 *lengthbyte = ptr++; // Record where the length is going to go
while (*cstr && ptr < lim) *ptr++ = (mDNSu8)*cstr++; // Copy the data
*lengthbyte = (mDNSu8)(ptr - lengthbyte - 1); // Fill in the length byte
*ptr++ = 0; // Put the null root label on the end
if (*cstr) return(mDNSNULL); // Failure: We didn't successfully consume all input
else return(ptr); // Success: return new value of ptr
}
// AppendDNSNameString appends zero or more labels to an existing (possibly empty) domainname.
// The C string is in conventional DNS syntax:
// Textual labels, escaped as necessary using the usual DNS '\' notation, separated by dots.
// If successful, AppendDNSNameString returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// AppendDNSNameString returns mDNSNULL.
mDNSexport mDNSu8 *AppendDNSNameString(domainname *const name, const char *cstring)
{
const char *cstr = cstring;
mDNSu8 * ptr = name->c + DomainNameLength(name) - 1; // Find end of current name
const mDNSu8 *const lim = name->c + MAX_DOMAIN_NAME - 1; // Limit of how much we can add (not counting final zero)
while (*cstr && ptr < lim) // While more characters, and space to put them...
{
mDNSu8 *lengthbyte = ptr++; // Record where the length is going to go
if (*cstr == '.') { LogMsg("AppendDNSNameString: Illegal empty label in name \"%s\"", cstring); return(mDNSNULL); }
while (*cstr && *cstr != '.' && ptr < lim) // While we have characters in the label...
{
mDNSu8 c = (mDNSu8)*cstr++; // Read the character
if (c == '\\') // If escape character, check next character
{
c = (mDNSu8)*cstr++; // Assume we'll just take the next character
if (mDNSIsDigit(cstr[-1]) && mDNSIsDigit(cstr[0]) && mDNSIsDigit(cstr[1]))
{ // If three decimal digits,
int v0 = cstr[-1] - '0'; // then interpret as three-digit decimal
int v1 = cstr[ 0] - '0';
int v2 = cstr[ 1] - '0';
int val = v0 * 100 + v1 * 10 + v2;
if (val <= 255) { c = (mDNSu8)val; cstr += 2; } // If valid three-digit decimal value, use it
}
}
*ptr++ = c; // Write the character
}
if (*cstr) cstr++; // Skip over the trailing dot (if present)
if (ptr - lengthbyte - 1 > MAX_DOMAIN_LABEL) // If illegal label, abort
return(mDNSNULL);
*lengthbyte = (mDNSu8)(ptr - lengthbyte - 1); // Fill in the length byte
}
*ptr++ = 0; // Put the null root label on the end
if (*cstr) return(mDNSNULL); // Failure: We didn't successfully consume all input
else return(ptr); // Success: return new value of ptr
}
// AppendDomainLabel appends a single label to a name.
// If successful, AppendDomainLabel returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// AppendDomainLabel returns mDNSNULL.
mDNSexport mDNSu8 *AppendDomainLabel(domainname *const name, const domainlabel *const label)
{
int i;
mDNSu8 *ptr = name->c + DomainNameLength(name) - 1;
// Check label is legal
if (label->c[0] > MAX_DOMAIN_LABEL) return(mDNSNULL);
// Check that ptr + length byte + data bytes + final zero does not exceed our limit
if (ptr + 1 + label->c[0] + 1 > name->c + MAX_DOMAIN_NAME) return(mDNSNULL);
for (i=0; i<=label->c[0]; i++) *ptr++ = label->c[i]; // Copy the label data
*ptr++ = 0; // Put the null root label on the end
return(ptr);
}
mDNSexport mDNSu8 *AppendDomainName(domainname *const name, const domainname *const append)
{
mDNSu8 * ptr = name->c + DomainNameLength(name) - 1; // Find end of current name
const mDNSu8 *const lim = name->c + MAX_DOMAIN_NAME - 1; // Limit of how much we can add (not counting final zero)
const mDNSu8 * src = append->c;
while (src[0])
{
int i;
if (ptr + 1 + src[0] > lim) return(mDNSNULL);
for (i=0; i<=src[0]; i++) *ptr++ = src[i];
*ptr = 0; // Put the null root label on the end
src += i;
}
return(ptr);
}
// MakeDomainLabelFromLiteralString makes a single domain label from a single literal C string (with no escaping).
// If successful, MakeDomainLabelFromLiteralString returns mDNStrue.
// If unable to convert the whole string to a legal domain label (i.e. because length is more than 63 bytes) then
// MakeDomainLabelFromLiteralString makes a legal domain label from the first 63 bytes of the string and returns mDNSfalse.
// In some cases silently truncated oversized names to 63 bytes is acceptable, so the return result may be ignored.
// In other cases silent truncation may not be acceptable, so in those cases the calling function needs to check the return result.
mDNSexport mDNSBool MakeDomainLabelFromLiteralString(domainlabel *const label, const char *cstr)
{
mDNSu8 * ptr = label->c + 1; // Where we're putting it
const mDNSu8 *const limit = label->c + 1 + MAX_DOMAIN_LABEL; // The maximum we can put
while (*cstr && ptr < limit) *ptr++ = (mDNSu8)*cstr++; // Copy the label
label->c[0] = (mDNSu8)(ptr - label->c - 1); // Set the length byte
return(*cstr == 0); // Return mDNStrue if we successfully consumed all input
}
// MakeDomainNameFromDNSNameString makes a native DNS-format domainname from a C string.
// The C string is in conventional DNS syntax:
// Textual labels, escaped as necessary using the usual DNS '\' notation, separated by dots.
// If successful, MakeDomainNameFromDNSNameString returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// MakeDomainNameFromDNSNameString returns mDNSNULL.
mDNSexport mDNSu8 *MakeDomainNameFromDNSNameString(domainname *const name, const char *cstr)
{
name->c[0] = 0; // Make an empty domain name
return(AppendDNSNameString(name, cstr)); // And then add this string to it
}
mDNSexport char *ConvertDomainLabelToCString_withescape(const domainlabel *const label, char *ptr, char esc)
{
const mDNSu8 * src = label->c; // Domain label we're reading
const mDNSu8 len = *src++; // Read length of this (non-null) label
const mDNSu8 *const end = src + len; // Work out where the label ends
if (len > MAX_DOMAIN_LABEL) return(mDNSNULL); // If illegal label, abort
while (src < end) // While we have characters in the label
{
mDNSu8 c = *src++;
if (esc)
{
if (c == '.' || c == esc) // If character is a dot or the escape character
*ptr++ = esc; // Output escape character
else if (c <= ' ') // If non-printing ascii,
{ // Output decimal escape sequence
*ptr++ = esc;
*ptr++ = (char) ('0' + (c / 100) );
*ptr++ = (char) ('0' + (c / 10) % 10);
c = (mDNSu8)('0' + (c ) % 10);
}
}
*ptr++ = (char)c; // Copy the character
}
*ptr = 0; // Null-terminate the string
return(ptr); // and return
}
// Note: To guarantee that there will be no possible overrun, cstr must be at least MAX_ESCAPED_DOMAIN_NAME (1009 bytes)
mDNSexport char *ConvertDomainNameToCString_withescape(const domainname *const name, char *ptr, char esc)
{
const mDNSu8 *src = name->c; // Domain name we're reading
const mDNSu8 *const max = name->c + MAX_DOMAIN_NAME; // Maximum that's valid
if (*src == 0) *ptr++ = '.'; // Special case: For root, just write a dot
while (*src) // While more characters in the domain name
{
if (src + 1 + *src >= max) return(mDNSNULL);
ptr = ConvertDomainLabelToCString_withescape((const domainlabel *)src, ptr, esc);
if (!ptr) return(mDNSNULL);
src += 1 + *src;
*ptr++ = '.'; // Write the dot after the label
}
*ptr++ = 0; // Null-terminate the string
return(ptr); // and return
}
// RFC 1034 rules:
// Host names must start with a letter, end with a letter or digit,
// and have as interior characters only letters, digits, and hyphen.
// This was subsequently modified in RFC 1123 to allow the first character to be either a letter or a digit
mDNSexport void ConvertUTF8PstringToRFC1034HostLabel(const mDNSu8 UTF8Name[], domainlabel *const hostlabel)
{
const mDNSu8 * src = &UTF8Name[1];
const mDNSu8 *const end = &UTF8Name[1] + UTF8Name[0];
mDNSu8 * ptr = &hostlabel->c[1];
const mDNSu8 *const lim = &hostlabel->c[1] + MAX_DOMAIN_LABEL;
while (src < end)
{
// Delete apostrophes from source name
if (src[0] == '\'') { src++; continue; } // Standard straight single quote
if (src + 2 < end && src[0] == 0xE2 && src[1] == 0x80 && src[2] == 0x99)
{ src += 3; continue; } // Unicode curly apostrophe
if (ptr < lim)
{
if (mDNSValidHostChar(*src, (ptr > &hostlabel->c[1]), (src < end-1))) *ptr++ = *src;
else if (ptr > &hostlabel->c[1] && ptr[-1] != '-') *ptr++ = '-';
}
src++;
}
while (ptr > &hostlabel->c[1] && ptr[-1] == '-') ptr--; // Truncate trailing '-' marks
hostlabel->c[0] = (mDNSu8)(ptr - &hostlabel->c[1]);
}
#define ValidTransportProtocol(X) ( (X)[0] == 4 && (X)[1] == '_' && \
((((X)[2] | 0x20) == 'u' && ((X)[3] | 0x20) == 'd') || (((X)[2] | 0x20) == 't' && ((X)[3] | 0x20) == 'c')) && \
((X)[4] | 0x20) == 'p')
mDNSexport mDNSu8 *ConstructServiceName(domainname *const fqdn,
const domainlabel *name, const domainname *type, const domainname *const domain)
{
int i, len;
mDNSu8 *dst = fqdn->c;
const mDNSu8 *src;
const char *errormsg;
#if APPLE_OSX_mDNSResponder
mDNSBool loggedUnderscore = mDNSfalse;
static char typeBuf[MAX_ESCAPED_DOMAIN_NAME];
#endif
// In the case where there is no name (and ONLY in that case),
// a single-label subtype is allowed as the first label of a three-part "type"
if (!name && type)
{
const mDNSu8 *s0 = type->c;
if (s0[0] && s0[0] < 0x40) // If legal first label (at least one character, and no more than 63)
{
const mDNSu8 * s1 = s0 + 1 + s0[0];
if (s1[0] && s1[0] < 0x40) // and legal second label (at least one character, and no more than 63)
{
const mDNSu8 *s2 = s1 + 1 + s1[0];
if (s2[0] && s2[0] < 0x40 && s2[1+s2[0]] == 0) // and we have three and only three labels
{
static const mDNSu8 SubTypeLabel[5] = "\x04_sub";
src = s0; // Copy the first label
len = *src;
for (i=0; i <= len; i++) *dst++ = *src++;
for (i=0; i < (int)sizeof(SubTypeLabel); i++) *dst++ = SubTypeLabel[i];
type = (const domainname *)s1;
// Special support to enable the DNSServiceBrowse call made by Bonjour Browser
// For these queries, we retract the "._sub" we just added between the subtype and the main type
// Remove after Bonjour Browser is updated to use DNSServiceQueryRecord instead of DNSServiceBrowse
if (SameDomainName((domainname*)s0, (const domainname*)"\x09_services\x07_dns-sd\x04_udp"))
dst -= sizeof(SubTypeLabel);
}
}
}
}
if (name && name->c[0])
{
src = name->c; // Put the service name into the domain name
len = *src;
if (len >= 0x40) { errormsg = "Service instance name too long"; goto fail; }
for (i=0; i<=len; i++) *dst++ = *src++;
}
else
name = (domainlabel*)""; // Set this up to be non-null, to avoid errors if we have to call LogMsg() below
src = type->c; // Put the service type into the domain name
len = *src;
if (len < 2 || len > 16)
{
LogMsg("Bad service type in %#s.%##s%##s Application protocol name must be underscore plus 1-15 characters. "
"See <http://www.dns-sd.org/ServiceTypes.html>", name->c, type->c, domain->c);
#if APPLE_OSX_mDNSResponder
ConvertDomainNameToCString(type, typeBuf);
mDNSASLLog(mDNSNULL, "serviceType.nameTooLong", "noop", typeBuf, "");
#endif
}
if (len < 2 || len >= 0x40 || (len > 16 && !SameDomainName(domain, &localdomain))) return(mDNSNULL);
if (src[1] != '_') { errormsg = "Application protocol name must begin with underscore"; goto fail; }
for (i=2; i<=len; i++)
{
// Letters and digits are allowed anywhere
if (mDNSIsLetter(src[i]) || mDNSIsDigit(src[i])) continue;
// Hyphens are only allowed as interior characters
// Underscores are not supposed to be allowed at all, but for backwards compatibility with some old products we do allow them,
// with the same rule as hyphens
if ((src[i] == '-' || src[i] == '_') && i > 2 && i < len)
{
#if APPLE_OSX_mDNSResponder
if (src[i] == '_' && loggedUnderscore == mDNSfalse)
{
ConvertDomainNameToCString(type, typeBuf);
mDNSASLLog(mDNSNULL, "serviceType.nameWithUnderscore", "noop", typeBuf, "");
loggedUnderscore = mDNStrue;
}
#endif
continue;
}
errormsg = "Application protocol name must contain only letters, digits, and hyphens";
#if APPLE_OSX_mDNSResponder
{
ConvertDomainNameToCString(type, typeBuf);
mDNSASLLog(mDNSNULL, "serviceType.nameWithIllegalCharacters", "noop", typeBuf, "");
}
#endif
goto fail;
}
for (i=0; i<=len; i++) *dst++ = *src++;
len = *src;
if (!ValidTransportProtocol(src)) { errormsg = "Transport protocol name must be _udp or _tcp"; goto fail; }
for (i=0; i<=len; i++) *dst++ = *src++;
if (*src) { errormsg = "Service type must have only two labels"; goto fail; }
*dst = 0;
if (!domain->c[0]) { errormsg = "Service domain must be non-empty"; goto fail; }
if (SameDomainName(domain, (const domainname*)"\x05" "local" "\x04" "arpa"))
{ errormsg = "Illegal domain \"local.arpa.\" Use \"local.\" (or empty string)"; goto fail; }
dst = AppendDomainName(fqdn, domain);
if (!dst) { errormsg = "Service domain too long"; goto fail; }
return(dst);
fail:
LogMsg("ConstructServiceName: %s: %#s.%##s%##s", errormsg, name->c, type->c, domain->c);
return(mDNSNULL);
}
// A service name has the form: instance.application-protocol.transport-protocol.domain
// DeconstructServiceName is currently fairly forgiving: It doesn't try to enforce character
// set or length limits for the protocol names, and the final domain is allowed to be empty.
// However, if the given FQDN doesn't contain at least three labels,
// DeconstructServiceName will reject it and return mDNSfalse.
mDNSexport mDNSBool DeconstructServiceName(const domainname *const fqdn,
domainlabel *const name, domainname *const type, domainname *const domain)
{
int i, len;
const mDNSu8 *src = fqdn->c;
const mDNSu8 *max = fqdn->c + MAX_DOMAIN_NAME;
mDNSu8 *dst;
dst = name->c; // Extract the service name
len = *src;
if (!len) { debugf("DeconstructServiceName: FQDN empty!"); return(mDNSfalse); }
if (len >= 0x40) { debugf("DeconstructServiceName: Instance name too long"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
dst = type->c; // Extract the service type
len = *src;
if (!len) { debugf("DeconstructServiceName: FQDN contains only one label!"); return(mDNSfalse); }
if (len >= 0x40) { debugf("DeconstructServiceName: Application protocol name too long"); return(mDNSfalse); }
if (src[1] != '_'){ debugf("DeconstructServiceName: No _ at start of application protocol"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
len = *src;
if (!len) { debugf("DeconstructServiceName: FQDN contains only two labels!"); return(mDNSfalse); }
if (!ValidTransportProtocol(src))
{ debugf("DeconstructServiceName: Transport protocol must be _udp or _tcp"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
*dst++ = 0; // Put terminator on the end of service type
dst = domain->c; // Extract the service domain
while (*src)
{
len = *src;
if (len >= 0x40)
{ debugf("DeconstructServiceName: Label in service domain too long"); return(mDNSfalse); }
if (src + 1 + len + 1 >= max)
{ debugf("DeconstructServiceName: Total service domain too long"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
}
*dst++ = 0; // Put the null root label on the end
return(mDNStrue);
}
// Notes on UTF-8:
// 0xxxxxxx represents a 7-bit ASCII value from 0x00 to 0x7F
// 10xxxxxx is a continuation byte of a multi-byte character
// 110xxxxx is the first byte of a 2-byte character (11 effective bits; values 0x 80 - 0x 800-1)
// 1110xxxx is the first byte of a 3-byte character (16 effective bits; values 0x 800 - 0x 10000-1)
// 11110xxx is the first byte of a 4-byte character (21 effective bits; values 0x 10000 - 0x 200000-1)
// 111110xx is the first byte of a 5-byte character (26 effective bits; values 0x 200000 - 0x 4000000-1)
// 1111110x is the first byte of a 6-byte character (31 effective bits; values 0x4000000 - 0x80000000-1)
//
// UTF-16 surrogate pairs are used in UTF-16 to encode values larger than 0xFFFF.
// Although UTF-16 surrogate pairs are not supposed to appear in legal UTF-8, we want to be defensive
// about that too. (See <http://www.unicode.org/faq/utf_bom.html#34>, "What are surrogates?")
// The first of pair is a UTF-16 value in the range 0xD800-0xDBFF (11101101 1010xxxx 10xxxxxx in UTF-8),
// and the second is a UTF-16 value in the range 0xDC00-0xDFFF (11101101 1011xxxx 10xxxxxx in UTF-8).
mDNSexport mDNSu32 TruncateUTF8ToLength(mDNSu8 *string, mDNSu32 length, mDNSu32 max)
{
if (length > max)
{
mDNSu8 c1 = string[max]; // First byte after cut point
mDNSu8 c2 = (max+1 < length) ? string[max+1] : (mDNSu8)0xB0; // Second byte after cut point
length = max; // Trim length down
while (length > 0)
{
// Check if the byte right after the chop point is a UTF-8 continuation byte,
// or if the character right after the chop point is the second of a UTF-16 surrogate pair.
// If so, then we continue to chop more bytes until we get to a legal chop point.
mDNSBool continuation = ((c1 & 0xC0) == 0x80);
mDNSBool secondsurrogate = (c1 == 0xED && (c2 & 0xF0) == 0xB0);
if (!continuation && !secondsurrogate) break;
c2 = c1;
c1 = string[--length];
}
// Having truncated characters off the end of our string, also cut off any residual white space
while (length > 0 && string[length-1] <= ' ') length--;
}
return(length);
}
// Returns true if a rich text label ends in " (nnn)", or if an RFC 1034
// name ends in "-nnn", where n is some decimal number.
mDNSexport mDNSBool LabelContainsSuffix(const domainlabel *const name, const mDNSBool RichText)
{
mDNSu16 l = name->c[0];
if (RichText)
{
if (l < 4) return mDNSfalse; // Need at least " (2)"
if (name->c[l--] != ')') return mDNSfalse; // Last char must be ')'
if (!mDNSIsDigit(name->c[l])) return mDNSfalse; // Preceeded by a digit
l--;
while (l > 2 && mDNSIsDigit(name->c[l])) l--; // Strip off digits
return (name->c[l] == '(' && name->c[l - 1] == ' ');
}
else
{
if (l < 2) return mDNSfalse; // Need at least "-2"
if (!mDNSIsDigit(name->c[l])) return mDNSfalse; // Last char must be a digit
l--;
while (l > 2 && mDNSIsDigit(name->c[l])) l--; // Strip off digits
return (name->c[l] == '-');
}
}
// removes an auto-generated suffix (appended on a name collision) from a label. caller is
// responsible for ensuring that the label does indeed contain a suffix. returns the number
// from the suffix that was removed.
mDNSexport mDNSu32 RemoveLabelSuffix(domainlabel *name, mDNSBool RichText)
{
mDNSu32 val = 0, multiplier = 1;
// Chop closing parentheses from RichText suffix
if (RichText && name->c[0] >= 1 && name->c[name->c[0]] == ')') name->c[0]--;
// Get any existing numerical suffix off the name
while (mDNSIsDigit(name->c[name->c[0]]))
{ val += (name->c[name->c[0]] - '0') * multiplier; multiplier *= 10; name->c[0]--; }
// Chop opening parentheses or dash from suffix
if (RichText)
{
if (name->c[0] >= 2 && name->c[name->c[0]] == '(' && name->c[name->c[0]-1] == ' ') name->c[0] -= 2;
}
else
{
if (name->c[0] >= 1 && name->c[name->c[0]] == '-') name->c[0] -= 1;
}
return(val);
}
// appends a numerical suffix to a label, with the number following a whitespace and enclosed
// in parentheses (rich text) or following two consecutive hyphens (RFC 1034 domain label).
mDNSexport void AppendLabelSuffix(domainlabel *const name, mDNSu32 val, const mDNSBool RichText)
{
mDNSu32 divisor = 1, chars = 2; // Shortest possible RFC1034 name suffix is 2 characters ("-2")
if (RichText) chars = 4; // Shortest possible RichText suffix is 4 characters (" (2)")
// Truncate trailing spaces from RichText names
if (RichText) while (name->c[name->c[0]] == ' ') name->c[0]--;
while (divisor < 0xFFFFFFFFUL/10 && val >= divisor * 10) { divisor *= 10; chars++; }
name->c[0] = (mDNSu8) TruncateUTF8ToLength(name->c+1, name->c[0], MAX_DOMAIN_LABEL - chars);
if (RichText) { name->c[++name->c[0]] = ' '; name->c[++name->c[0]] = '('; }
else { name->c[++name->c[0]] = '-'; }
while (divisor)
{
name->c[++name->c[0]] = (mDNSu8)('0' + val / divisor);
val %= divisor;
divisor /= 10;
}
if (RichText) name->c[++name->c[0]] = ')';
}
mDNSexport void IncrementLabelSuffix(domainlabel *name, mDNSBool RichText)
{
mDNSu32 val = 0;
if (LabelContainsSuffix(name, RichText))
val = RemoveLabelSuffix(name, RichText);
// If no existing suffix, start by renaming "Foo" as "Foo (2)" or "Foo-2" as appropriate.
// If existing suffix in the range 2-9, increment it.
// If we've had ten conflicts already, there are probably too many hosts trying to use the same name,
// so add a random increment to improve the chances of finding an available name next time.
if (val == 0) val = 2;
else if (val < 10) val++;
else val += 1 + mDNSRandom(99);
AppendLabelSuffix(name, val, RichText);
}
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Resource Record Utility Functions
#endif
// Set up a AuthRecord with sensible default values.
// These defaults may be overwritten with new values before mDNS_Register is called
mDNSexport void mDNS_SetupResourceRecord(AuthRecord *rr, RData *RDataStorage, mDNSInterfaceID InterfaceID,
mDNSu16 rrtype, mDNSu32 ttl, mDNSu8 RecordType, AuthRecType artype, mDNSRecordCallback Callback, void *Context)
{
//
// LocalOnly auth record can be created with LocalOnly InterfaceID or a valid InterfaceID.
// Most of the applications normally create with LocalOnly InterfaceID and we store them as
// such, so that we can deliver the response to questions that specify LocalOnly InterfaceID.
// LocalOnly resource records can also be created with valid InterfaceID which happens today
// when we create LocalOnly records for /etc/hosts.
if (InterfaceID == mDNSInterface_LocalOnly && artype != AuthRecordLocalOnly)
{
LogMsg("mDNS_SetupResourceRecord: ERROR!! Mismatch LocalOnly record InterfaceID %p called with artype %d", InterfaceID, artype);
return;
}
else if (InterfaceID == mDNSInterface_P2P && artype != AuthRecordP2P)
{
LogMsg("mDNS_SetupResourceRecord: ERROR!! Mismatch P2P record InterfaceID %p called with artype %d", InterfaceID, artype);
return;
}
else if (!InterfaceID && (artype == AuthRecordP2P || artype == AuthRecordLocalOnly))
{
LogMsg("mDNS_SetupResourceRecord: ERROR!! Mismatch InterfaceAny record InterfaceID %p called with artype %d", InterfaceID, artype);
return;
}
// Don't try to store a TTL bigger than we can represent in platform time units
if (ttl > 0x7FFFFFFFUL / mDNSPlatformOneSecond)
ttl = 0x7FFFFFFFUL / mDNSPlatformOneSecond;
else if (ttl == 0) // And Zero TTL is illegal
ttl = DefaultTTLforRRType(rrtype);
// Field Group 1: The actual information pertaining to this resource record
rr->resrec.RecordType = RecordType;
rr->resrec.InterfaceID = InterfaceID;
rr->resrec.name = &rr->namestorage;
rr->resrec.rrtype = rrtype;
rr->resrec.rrclass = kDNSClass_IN;
rr->resrec.rroriginalttl = ttl;
rr->resrec.rDNSServer = mDNSNULL;
// rr->resrec.rdlength = MUST set by client and/or in mDNS_Register_internal
// rr->resrec.rdestimate = set in mDNS_Register_internal
// rr->resrec.rdata = MUST be set by client
if (RDataStorage)
rr->resrec.rdata = RDataStorage;
else
{
rr->resrec.rdata = &rr->rdatastorage;
rr->resrec.rdata->MaxRDLength = sizeof(RDataBody);
}
// Field Group 2: Persistent metadata for Authoritative Records
rr->Additional1 = mDNSNULL;
rr->Additional2 = mDNSNULL;
rr->DependentOn = mDNSNULL;
rr->RRSet = mDNSNULL;
rr->RecordCallback = Callback;
rr->RecordContext = Context;
rr->AutoTarget = Target_Manual;
rr->AllowRemoteQuery = mDNSfalse;
rr->ForceMCast = mDNSfalse;
rr->WakeUp = zeroOwner;
rr->AddressProxy = zeroAddr;
rr->TimeRcvd = 0;
rr->TimeExpire = 0;
rr->ARType = artype;
// Field Group 3: Transient state for Authoritative Records (set in mDNS_Register_internal)
// Field Group 4: Transient uDNS state for Authoritative Records (set in mDNS_Register_internal)
// For now, until the uDNS code is fully integrated, it's helpful to zero the uDNS state fields here too, just in case
// (e.g. uDNS_RegisterService short-circuits the usual mDNS_Register_internal record registration calls, so a bunch
// of fields don't get set up properly. In particular, if we don't zero rr->QueuedRData then the uDNS code crashes.)
rr->state = regState_Zero;
rr->uselease = 0;
rr->expire = 0;
rr->Private = 0;
rr->updateid = zeroID;
rr->zone = rr->resrec.name;
rr->nta = mDNSNULL;
rr->tcp = mDNSNULL;
rr->OrigRData = 0;
rr->OrigRDLen = 0;
rr->InFlightRData = 0;
rr->InFlightRDLen = 0;
rr->QueuedRData = 0;
rr->QueuedRDLen = 0;
mDNSPlatformMemZero(&rr->NATinfo, sizeof(rr->NATinfo));
rr->SRVChanged = mDNSfalse;
rr->mState = mergeState_Zero;
rr->namestorage.c[0] = 0; // MUST be set by client before calling mDNS_Register()
}
mDNSexport void mDNS_SetupQuestion(DNSQuestion *const q, const mDNSInterfaceID InterfaceID, const domainname *const name,
const mDNSu16 qtype, mDNSQuestionCallback *const callback, void *const context)
{
q->InterfaceID = InterfaceID;
q->Target = zeroAddr;
AssignDomainName(&q->qname, name);
q->qtype = qtype;
q->qclass = kDNSClass_IN;
q->LongLived = (qtype == kDNSType_PTR);
q->ExpectUnique = (qtype != kDNSType_PTR);
q->ForceMCast = mDNSfalse;
q->ReturnIntermed = mDNSfalse;
q->SuppressUnusable = mDNSfalse;
q->SearchListIndex = 0;
q->AppendSearchDomains = 0;
q->RetryWithSearchDomains = mDNSfalse;
q->TimeoutQuestion = 0;
q->WakeOnResolve = 0;
q->qnameOrig = mDNSNULL;
q->QuestionCallback = callback;
q->QuestionContext = context;
}
mDNSexport mDNSu32 RDataHashValue(const ResourceRecord *const rr)
{
int len = rr->rdlength;
const RDataBody2 *const rdb = (RDataBody2 *)rr->rdata->u.data;
switch(rr->rrtype)
{
case kDNSType_NS:
case kDNSType_CNAME:
case kDNSType_PTR:
case kDNSType_DNAME: return DomainNameHashValue(&rdb->name);
case kDNSType_SOA: return rdb->soa.serial +
rdb->soa.refresh +
rdb->soa.retry +
rdb->soa.expire +
rdb->soa.min +
DomainNameHashValue(&rdb->soa.mname) +
DomainNameHashValue(&rdb->soa.rname);
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: return DomainNameHashValue(&rdb->mx.exchange);
case kDNSType_RP: return DomainNameHashValue(&rdb->rp.mbox) + DomainNameHashValue(&rdb->rp.txt);
case kDNSType_PX: return DomainNameHashValue(&rdb->px.map822) + DomainNameHashValue(&rdb->px.mapx400);
case kDNSType_SRV: return DomainNameHashValue(&rdb->srv.target);
case kDNSType_OPT: return 0; // OPT is a pseudo-RR container structure; makes no sense to compare
case kDNSType_NSEC: len = sizeof(rdataNSEC); // Use in-memory length of 32, and fall through default checksum computation below
default:
{
mDNSu32 sum = 0;
int i;
for (i=0; i+1 < len; i+=2)
{
sum += (((mDNSu32)(rdb->data[i])) << 8) | rdb->data[i+1];
sum = (sum<<3) | (sum>>29);
}
if (i < len)
{
sum += ((mDNSu32)(rdb->data[i])) << 8;
}
return(sum);
}
}
}
// r1 has to be a full ResourceRecord including rrtype and rdlength
// r2 is just a bare RDataBody, which MUST be the same rrtype and rdlength as r1
mDNSexport mDNSBool SameRDataBody(const ResourceRecord *const r1, const RDataBody *const r2, DomainNameComparisonFn *samename)
{
const RDataBody2 *const b1 = (RDataBody2 *)r1->rdata->u.data;
const RDataBody2 *const b2 = (RDataBody2 *)r2;
switch(r1->rrtype)
{
case kDNSType_NS:
case kDNSType_CNAME:
case kDNSType_PTR:
case kDNSType_DNAME:return(SameDomainName(&b1->name, &b2->name));
case kDNSType_SOA: return(mDNSBool)( b1->soa.serial == b2->soa.serial &&
b1->soa.refresh == b2->soa.refresh &&
b1->soa.retry == b2->soa.retry &&
b1->soa.expire == b2->soa.expire &&
b1->soa.min == b2->soa.min &&
samename(&b1->soa.mname, &b2->soa.mname) &&
samename(&b1->soa.rname, &b2->soa.rname));
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: return(mDNSBool)( b1->mx.preference == b2->mx.preference &&
samename(&b1->mx.exchange, &b2->mx.exchange));
case kDNSType_RP: return(mDNSBool)( samename(&b1->rp.mbox, &b2->rp.mbox) &&
samename(&b1->rp.txt, &b2->rp.txt));
case kDNSType_PX: return(mDNSBool)( b1->px.preference == b2->px.preference &&
samename(&b1->px.map822, &b2->px.map822) &&
samename(&b1->px.mapx400, &b2->px.mapx400));
case kDNSType_SRV: return(mDNSBool)( b1->srv.priority == b2->srv.priority &&
b1->srv.weight == b2->srv.weight &&
mDNSSameIPPort(b1->srv.port, b2->srv.port) &&
samename(&b1->srv.target, &b2->srv.target));
case kDNSType_OPT: return mDNSfalse; // OPT is a pseudo-RR container structure; makes no sense to compare
case kDNSType_NSEC: return(mDNSPlatformMemSame(b1->data, b2->data, sizeof(rdataNSEC)));
default: return(mDNSPlatformMemSame(b1->data, b2->data, r1->rdlength));
}
}
// ResourceRecordAnswersQuestion returns mDNStrue if the given resource record is a valid answer to the given question.
// SameNameRecordAnswersQuestion is the same, except it skips the expensive SameDomainName() call.
// SameDomainName() is generally cheap when the names don't match, but expensive when they do match,
// because it has to check all the way to the end of the names to be sure.
// In cases where we know in advance that the names match it's especially advantageous to skip the
// SameDomainName() call because that's precisely the time when it's most expensive and least useful.
mDNSexport mDNSBool SameNameRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q)
{
// LocalOnly/P2P questions can be answered with AuthRecordAny in this function. LocalOnly/P2P records
// are handled in LocalOnlyRecordAnswersQuestion
if ((rr->InterfaceID == mDNSInterface_LocalOnly) || (rr->InterfaceID == mDNSInterface_P2P))
{
LogMsg("SameNameRecordAnswersQuestion: ERROR!! called with LocalOnly ResourceRecord %p, Question %p", rr->InterfaceID, q->InterfaceID);
return mDNSfalse;
}
if (rr->InterfaceID &&
q ->InterfaceID && q->InterfaceID != mDNSInterface_LocalOnly &&
rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
// Resource record received via unicast, the DNSServer entries should match ?
if (!rr->InterfaceID && rr->rDNSServer != q->qDNSServer) return(mDNSfalse);
// If ResourceRecord received via multicast, but question was unicast, then shouldn't use record to answer this question
if (rr->InterfaceID && !mDNSOpaque16IsZero(q->TargetQID)) return(mDNSfalse);
// RR type CNAME matches any query type. QTYPE ANY matches any RR type. QCLASS ANY matches any RR class.
if (!RRTypeAnswersQuestionType(rr,q->qtype)) return(mDNSfalse);
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(mDNStrue);
}
mDNSexport mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q)
{
// LocalOnly/P2P questions can be answered with AuthRecordAny in this function. LocalOnly/P2P records
// are handled in LocalOnlyRecordAnswersQuestion
if ((rr->InterfaceID == mDNSInterface_LocalOnly) || (rr->InterfaceID == mDNSInterface_P2P))
{
LogMsg("ResourceRecordAnswersQuestion: ERROR!! called with LocalOnly/P2P ResourceRecord %p, Question %p", rr->InterfaceID, q->InterfaceID);
return mDNSfalse;
}
if (rr->InterfaceID &&
q ->InterfaceID && q->InterfaceID != mDNSInterface_LocalOnly &&
rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
// Resource record received via unicast, the DNSServer entries should match ?
if (!rr->InterfaceID && rr->rDNSServer != q->qDNSServer) return(mDNSfalse);
// If ResourceRecord received via multicast, but question was unicast, then shouldn't use record to answer this question.
if (rr->InterfaceID && !mDNSOpaque16IsZero(q->TargetQID)) return(mDNSfalse);
// RR type CNAME matches any query type. QTYPE ANY matches any RR type. QCLASS ANY matches any RR class.
if (!RRTypeAnswersQuestionType(rr,q->qtype)) return(mDNSfalse);
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
// We have a separate function to handle LocalOnly AuthRecords because they can be created with
// a valid InterfaceID (e.g., scoped /etc/hosts) and can be used to answer unicast questions unlike
// multicast resource records (which has a valid InterfaceID) which can't be used to answer
// unicast questions. ResourceRecordAnswersQuestion/SameNameRecordAnswersQuestion can't tell whether
// a resource record is multicast or LocalOnly by just looking at the ResourceRecord because
// LocalOnly records are truly identified by ARType in the AuthRecord. As P2P and LocalOnly record
// are kept in the same hash table, we use the same function to make it easy for the callers when
// they walk the hash table to answer LocalOnly/P2P questions
//
mDNSexport mDNSBool LocalOnlyRecordAnswersQuestion(AuthRecord *const ar, const DNSQuestion *const q)
{
ResourceRecord *rr = &ar->resrec;
// mDNSInterface_Any questions can be answered with LocalOnly/P2P records in this function. AuthRecord_Any
// records are handled in ResourceRecordAnswersQuestion/SameNameRecordAnswersQuestion
if (RRAny(ar))
{
LogMsg("LocalOnlyRecordAnswersQuestion: ERROR!! called with regular AuthRecordAny %##s", rr->name->c);
return mDNSfalse;
}
// Questions with mDNSInterface_LocalOnly InterfaceID should be answered with all resource records that are
// *local* to the machine. These include resource records that have InterfaceID set to mDNSInterface_LocalOnly,
// mDNSInterface_Any and any other real InterfaceID. Hence, LocalOnly questions should not be checked against
// the InterfaceID in the resource record.
//
// mDNSInterface_Unicast does not indicate any scope and hence treat them like mDNSInterface_Any.
if (rr->InterfaceID &&
q->InterfaceID && q->InterfaceID != mDNSInterface_LocalOnly && q->InterfaceID != mDNSInterface_Unicast &&
rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
// Entries in /etc/hosts are added as LocalOnly resource records. The LocalOnly resource records
// may have a scope e.g., fe80::1%en0. The question may be scoped or not: the InterfaceID may be set
// to mDNSInterface_Any, mDNSInterface_LocalOnly or a real InterfaceID (scoped).
//
// 1) Question: Any, LocalOnly Record: no scope. This question should be answered with this record.
//
// 2) Question: Any, LocalOnly Record: scoped. This question should be answered with the record because
// traditionally applications never specify scope e.g., getaddrinfo, but need to be able
// to get to /etc/hosts entries.
//
// 3) Question: Scoped (LocalOnly or InterfaceID), LocalOnly Record: no scope. This is the inverse of (2).
// If we register a LocalOnly record, we need to answer a LocalOnly question. If the /etc/hosts has a
// non scoped entry, it may not make sense to answer a scoped question. But we can't tell these two
// cases apart. As we currently answer LocalOnly question with LocalOnly record, we continue to do so.
//
// 4) Question: Scoped (LocalOnly or InterfaceID), LocalOnly Record: scoped. LocalOnly questions should be
// answered with any resource record where as if it has a valid InterfaceID, the scope should match.
//
// (1) and (2) is bypassed because we check for a non-NULL InterfaceID above. For (3), the InterfaceID is NULL
// and hence bypassed above. For (4) we bypassed LocalOnly questions and checked the scope of the record
// against the question.
//
// For P2P, InterfaceIDs of the question and the record should match.
// If ResourceRecord received via multicast, but question was unicast, then shouldn't use record to answer this question.
// LocalOnly authoritative answers are exempt. LocalOnly authoritative answers are used for /etc/host entries.
// We don't want a local process to be able to create a fake LocalOnly address record for "www.bigbank.com" which would then
// cause other applications (e.g. Safari) to connect to the wrong address. The rpc to register records filters out records
// with names that don't end in local and have mDNSInterface_LocalOnly set.
//
// Note: The check is bypassed for LocalOnly and for P2P it is not needed as only .local records are registered and for
// a question to match its names, it also has to end in .local and that question can't be a unicast question (See
// Question_uDNS macro and its usage). As P2P does not enforce .local only registrations we still make this check
// and also makes it future proof.
if (ar->ARType != AuthRecordLocalOnly && rr->InterfaceID && !mDNSOpaque16IsZero(q->TargetQID)) return(mDNSfalse);
// RR type CNAME matches any query type. QTYPE ANY matches any RR type. QCLASS ANY matches any RR class.
if (!RRTypeAnswersQuestionType(rr,q->qtype)) return(mDNSfalse);
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
mDNSexport mDNSBool AnyTypeRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q)
{
// LocalOnly/P2P questions can be answered with AuthRecordAny in this function. LocalOnly/P2P records
// are handled in LocalOnlyRecordAnswersQuestion
if ((rr->InterfaceID == mDNSInterface_LocalOnly) || (rr->InterfaceID == mDNSInterface_P2P))
{
LogMsg("AnyTypeRecordAnswersQuestion: ERROR!! called with LocalOnly ResourceRecord %p, Question %p", rr->InterfaceID, q->InterfaceID);
return mDNSfalse;
}
if (rr->InterfaceID &&
q ->InterfaceID && q->InterfaceID != mDNSInterface_LocalOnly &&
rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
// Resource record received via unicast, the DNSServer entries should match ?
// Note that Auth Records are normally setup with NULL InterfaceID and
// both the DNSServers are assumed to be NULL in that case
if (!rr->InterfaceID && rr->rDNSServer != q->qDNSServer) return(mDNSfalse);
// If ResourceRecord received via multicast, but question was unicast, then shouldn't use record to answer this question
if (rr->InterfaceID && !mDNSOpaque16IsZero(q->TargetQID)) return(mDNSfalse);
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
// This is called with both unicast resource record and multicast resource record. The question that
// received the unicast response could be the regular unicast response from a DNS server or a response
// to a mDNS QU query. The main reason we need this function is that we can't compare DNSServers between the
// question and the resource record because the resource record is not completely initialized in
// mDNSCoreReceiveResponse when this function is called.
mDNSexport mDNSBool ResourceRecordAnswersUnicastResponse(const ResourceRecord *const rr, const DNSQuestion *const q)
{
// For resource records created using multicast, the InterfaceIDs have to match
if (rr->InterfaceID &&
q->InterfaceID && rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
// If ResourceRecord received via multicast, but question was unicast, then shouldn't use record to answer this question.
if (rr->InterfaceID && !mDNSOpaque16IsZero(q->TargetQID)) return(mDNSfalse);
// RR type CNAME matches any query type. QTYPE ANY matches any RR type. QCLASS ANY matches any RR class.
if (!RRTypeAnswersQuestionType(rr,q->qtype)) return(mDNSfalse);
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
mDNSexport mDNSu16 GetRDLength(const ResourceRecord *const rr, mDNSBool estimate)
{
const RDataBody2 *const rd = (RDataBody2 *)rr->rdata->u.data;
const domainname *const name = estimate ? rr->name : mDNSNULL;
if (rr->rrclass == kDNSQClass_ANY) return(rr->rdlength); // Used in update packets to mean "Delete An RRset" (RFC 2136)
else switch (rr->rrtype)
{
case kDNSType_A: return(sizeof(rd->ipv4));
case kDNSType_NS:
case kDNSType_CNAME:
case kDNSType_PTR:
case kDNSType_DNAME:return(CompressedDomainNameLength(&rd->name, name));
case kDNSType_SOA: return(mDNSu16)(CompressedDomainNameLength(&rd->soa.mname, name) +
CompressedDomainNameLength(&rd->soa.rname, name) +
5 * sizeof(mDNSOpaque32));
case kDNSType_NULL:
case kDNSType_TSIG:
case kDNSType_TXT:
case kDNSType_X25:
case kDNSType_ISDN:
case kDNSType_LOC:
case kDNSType_DHCID:return(rr->rdlength); // Not self-describing, so have to just trust rdlength
case kDNSType_HINFO:return(mDNSu16)(2 + (int)rd->data[0] + (int)rd->data[1 + (int)rd->data[0]]);
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: return(mDNSu16)(2 + CompressedDomainNameLength(&rd->mx.exchange, name));
case kDNSType_RP: return(mDNSu16)(CompressedDomainNameLength(&rd->rp.mbox, name) +
CompressedDomainNameLength(&rd->rp.txt, name));
case kDNSType_PX: return(mDNSu16)(2 + CompressedDomainNameLength(&rd->px.map822, name) +
CompressedDomainNameLength(&rd->px.mapx400, name));
case kDNSType_AAAA: return(sizeof(rd->ipv6));
case kDNSType_SRV: return(mDNSu16)(6 + CompressedDomainNameLength(&rd->srv.target, name));
case kDNSType_OPT: return(rr->rdlength);
case kDNSType_NSEC: {
int i;
for (i=sizeof(rdataNSEC); i>0; i--) if (rd->nsec.bitmap[i-1]) break;
// For our simplified use of NSEC synthetic records:
// nextname is always the record's own name,
// and if we have at least one record type that exists,
// - the block number is always 0,
// - the count byte is a value in the range 1-32,
// - followed by the 1-32 data bytes
return(mDNSu16)((estimate ? 2 : DomainNameLength(rr->name)) + (i ? (2 + i) : 0));
}
default: debugf("Warning! Don't know how to get length of resource type %d", rr->rrtype);
return(rr->rdlength);
}
}
// When a local client registers (or updates) a record, we use this routine to do some simple validation checks
// to help reduce the risk of bogus malformed data on the network
mDNSexport mDNSBool ValidateRData(const mDNSu16 rrtype, const mDNSu16 rdlength, const RData *const rd)
{
mDNSu16 len;
switch(rrtype)
{
case kDNSType_A: return(rdlength == sizeof(mDNSv4Addr));
case kDNSType_NS: // Same as PTR
case kDNSType_MD: // Same as PTR
case kDNSType_MF: // Same as PTR
case kDNSType_CNAME:// Same as PTR
//case kDNSType_SOA not checked
case kDNSType_MB: // Same as PTR
case kDNSType_MG: // Same as PTR
case kDNSType_MR: // Same as PTR
//case kDNSType_NULL not checked (no specified format, so always valid)
//case kDNSType_WKS not checked
case kDNSType_PTR: len = DomainNameLengthLimit(&rd->u.name, rd->u.data + rdlength);
return(len <= MAX_DOMAIN_NAME && rdlength == len);
case kDNSType_HINFO:// Same as TXT (roughly)
case kDNSType_MINFO:// Same as TXT (roughly)
case kDNSType_TXT: if (!rdlength) return(mDNSfalse); // TXT record has to be at least one byte (RFC 1035)
{
const mDNSu8 *ptr = rd->u.txt.c;
const mDNSu8 *end = rd->u.txt.c + rdlength;
while (ptr < end) ptr += 1 + ptr[0];
return (ptr == end);
}
case kDNSType_AAAA: return(rdlength == sizeof(mDNSv6Addr));
case kDNSType_MX: // Must be at least two-byte preference, plus domainname
// Call to DomainNameLengthLimit() implicitly enforces both requirements for us
len = DomainNameLengthLimit(&rd->u.mx.exchange, rd->u.data + rdlength);
return(len <= MAX_DOMAIN_NAME && rdlength == 2+len);
case kDNSType_SRV: // Must be at least priority+weight+port, plus domainname
// Call to DomainNameLengthLimit() implicitly enforces both requirements for us
len = DomainNameLengthLimit(&rd->u.srv.target, rd->u.data + rdlength);
return(len <= MAX_DOMAIN_NAME && rdlength == 6+len);
//case kDNSType_NSEC not checked
default: return(mDNStrue); // Allow all other types without checking
}
}
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNS Message Creation Functions
#endif
mDNSexport void InitializeDNSMessage(DNSMessageHeader *h, mDNSOpaque16 id, mDNSOpaque16 flags)
{
h->id = id;
h->flags = flags;
h->numQuestions = 0;
h->numAnswers = 0;
h->numAuthorities = 0;
h->numAdditionals = 0;
}
mDNSexport const mDNSu8 *FindCompressionPointer(const mDNSu8 *const base, const mDNSu8 *const end, const mDNSu8 *const domname)
{
const mDNSu8 *result = end - *domname - 1;
if (*domname == 0) return(mDNSNULL); // There's no point trying to match just the root label
// This loop examines each possible starting position in packet, starting end of the packet and working backwards
while (result >= base)
{
// If the length byte and first character of the label match, then check further to see
// if this location in the packet will yield a useful name compression pointer.
if (result[0] == domname[0] && result[1] == domname[1])
{
const mDNSu8 *name = domname;
const mDNSu8 *targ = result;
while (targ + *name < end)
{
// First see if this label matches
int i;
const mDNSu8 *pointertarget;
for (i=0; i <= *name; i++) if (targ[i] != name[i]) break;
if (i <= *name) break; // If label did not match, bail out
targ += 1 + *name; // Else, did match, so advance target pointer
name += 1 + *name; // and proceed to check next label
if (*name == 0 && *targ == 0) return(result); // If no more labels, we found a match!
if (*name == 0) break; // If no more labels to match, we failed, so bail out
// The label matched, so now follow the pointer (if appropriate) and then see if the next label matches
if (targ[0] < 0x40) continue; // If length value, continue to check next label
if (targ[0] < 0xC0) break; // If 40-BF, not valid
if (targ+1 >= end) break; // Second byte not present!
pointertarget = base + (((mDNSu16)(targ[0] & 0x3F)) << 8) + targ[1];
if (targ < pointertarget) break; // Pointertarget must point *backwards* in the packet
if (pointertarget[0] >= 0x40) break; // Pointertarget must point to a valid length byte
targ = pointertarget;
}
}
result--; // We failed to match at this search position, so back up the tentative result pointer and try again
}
return(mDNSNULL);
}
// Put a string of dot-separated labels as length-prefixed labels
// domainname is a fully-qualified name (i.e. assumed to be ending in a dot, even if it doesn't)
// msg points to the message we're building (pass mDNSNULL if we don't want to use compression pointers)
// end points to the end of the message so far
// ptr points to where we want to put the name
// limit points to one byte past the end of the buffer that we must not overrun
// domainname is the name to put
mDNSexport mDNSu8 *putDomainNameAsLabels(const DNSMessage *const msg,
mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name)
{
const mDNSu8 *const base = (const mDNSu8 *)msg;
const mDNSu8 * np = name->c;
const mDNSu8 *const max = name->c + MAX_DOMAIN_NAME; // Maximum that's valid
const mDNSu8 * pointer = mDNSNULL;
const mDNSu8 *const searchlimit = ptr;
if (!ptr) { LogMsg("putDomainNameAsLabels %##s ptr is null", name->c); return(mDNSNULL); }
if (!*np) // If just writing one-byte root label, make sure we have space for that
{
if (ptr >= limit) return(mDNSNULL);
}
else // else, loop through writing labels and/or a compression offset
{
do {
if (*np > MAX_DOMAIN_LABEL)
{ LogMsg("Malformed domain name %##s (label more than 63 bytes)", name->c); return(mDNSNULL); }
// This check correctly allows for the final trailing root label:
// e.g.
// Suppose our domain name is exactly 256 bytes long, including the final trailing root label.
// Suppose np is now at name->c[249], and we're about to write our last non-null label ("local").
// We know that max will be at name->c[256]
// That means that np + 1 + 5 == max - 1, so we (just) pass the "if" test below, write our
// six bytes, then exit the loop, write the final terminating root label, and the domain
// name we've written is exactly 256 bytes long, exactly at the correct legal limit.
// If the name is one byte longer, then we fail the "if" test below, and correctly bail out.
if (np + 1 + *np >= max)
{ LogMsg("Malformed domain name %##s (more than 256 bytes)", name->c); return(mDNSNULL); }
if (base) pointer = FindCompressionPointer(base, searchlimit, np);
if (pointer) // Use a compression pointer if we can
{
const mDNSu16 offset = (mDNSu16)(pointer - base);
if (ptr+2 > limit) return(mDNSNULL); // If we don't have two bytes of space left, give up
*ptr++ = (mDNSu8)(0xC0 | (offset >> 8));
*ptr++ = (mDNSu8)( offset & 0xFF);
return(ptr);
}
else // Else copy one label and try again
{
int i;
mDNSu8 len = *np++;
// If we don't at least have enough space for this label *plus* a terminating zero on the end, give up
if (ptr + 1 + len >= limit) return(mDNSNULL);
*ptr++ = len;
for (i=0; i<len; i++) *ptr++ = *np++;
}
} while (*np); // While we've got characters remaining in the name, continue
}
*ptr++ = 0; // Put the final root label
return(ptr);
}
mDNSlocal mDNSu8 *putVal16(mDNSu8 *ptr, mDNSu16 val)
{
ptr[0] = (mDNSu8)((val >> 8 ) & 0xFF);
ptr[1] = (mDNSu8)((val ) & 0xFF);
return ptr + sizeof(mDNSOpaque16);
}
mDNSlocal mDNSu8 *putVal32(mDNSu8 *ptr, mDNSu32 val)
{
ptr[0] = (mDNSu8)((val >> 24) & 0xFF);
ptr[1] = (mDNSu8)((val >> 16) & 0xFF);
ptr[2] = (mDNSu8)((val >> 8) & 0xFF);
ptr[3] = (mDNSu8)((val ) & 0xFF);
return ptr + sizeof(mDNSu32);
}
// msg points to the message we're building (pass mDNSNULL if we don't want to use compression pointers)
mDNSexport mDNSu8 *putRData(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const ResourceRecord *const rr)
{
const RDataBody2 *const rdb = (RDataBody2 *)rr->rdata->u.data;
switch (rr->rrtype)
{
case kDNSType_A: if (rr->rdlength != 4)
{ debugf("putRData: Illegal length %d for kDNSType_A", rr->rdlength); return(mDNSNULL); }
if (ptr + 4 > limit) return(mDNSNULL);
*ptr++ = rdb->ipv4.b[0];
*ptr++ = rdb->ipv4.b[1];
*ptr++ = rdb->ipv4.b[2];
*ptr++ = rdb->ipv4.b[3];
return(ptr);
case kDNSType_NS:
case kDNSType_CNAME:
case kDNSType_PTR:
case kDNSType_DNAME:return(putDomainNameAsLabels(msg, ptr, limit, &rdb->name));
case kDNSType_SOA: ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->soa.mname);
if (!ptr) return(mDNSNULL);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->soa.rname);
if (!ptr || ptr + 20 > limit) return(mDNSNULL);
ptr = putVal32(ptr, rdb->soa.serial);
ptr = putVal32(ptr, rdb->soa.refresh);
ptr = putVal32(ptr, rdb->soa.retry);
ptr = putVal32(ptr, rdb->soa.expire);
ptr = putVal32(ptr, rdb->soa.min);
return(ptr);
case kDNSType_NULL:
case kDNSType_HINFO:
case kDNSType_TSIG:
case kDNSType_TXT:
case kDNSType_X25:
case kDNSType_ISDN:
case kDNSType_LOC:
case kDNSType_DHCID:if (ptr + rr->rdlength > limit) return(mDNSNULL);
mDNSPlatformMemCopy(ptr, rdb->data, rr->rdlength);
return(ptr + rr->rdlength);
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: if (ptr + 3 > limit) return(mDNSNULL);
ptr = putVal16(ptr, rdb->mx.preference);
return(putDomainNameAsLabels(msg, ptr, limit, &rdb->mx.exchange));
case kDNSType_RP: ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->rp.mbox);
if (!ptr) return(mDNSNULL);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->rp.txt);
return(ptr);
case kDNSType_PX: if (ptr + 5 > limit) return(mDNSNULL);
ptr = putVal16(ptr, rdb->px.preference);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->px.map822);
if (!ptr) return(mDNSNULL);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->px.mapx400);
return(ptr);
case kDNSType_AAAA: if (rr->rdlength != sizeof(rdb->ipv6))
{ debugf("putRData: Illegal length %d for kDNSType_AAAA", rr->rdlength); return(mDNSNULL); }
if (ptr + sizeof(rdb->ipv6) > limit) return(mDNSNULL);
mDNSPlatformMemCopy(ptr, &rdb->ipv6, sizeof(rdb->ipv6));
return(ptr + sizeof(rdb->ipv6));
case kDNSType_SRV: if (ptr + 7 > limit) return(mDNSNULL);
*ptr++ = (mDNSu8)(rdb->srv.priority >> 8);
*ptr++ = (mDNSu8)(rdb->srv.priority & 0xFF);
*ptr++ = (mDNSu8)(rdb->srv.weight >> 8);
*ptr++ = (mDNSu8)(rdb->srv.weight & 0xFF);
*ptr++ = rdb->srv.port.b[0];
*ptr++ = rdb->srv.port.b[1];
return(putDomainNameAsLabels(msg, ptr, limit, &rdb->srv.target));
case kDNSType_OPT: {
int len = 0;
const rdataOPT *opt;
const rdataOPT *const end = (const rdataOPT *)&rr->rdata->u.data[rr->rdlength];
for (opt = &rr->rdata->u.opt[0]; opt < end; opt++) len += DNSOpt_Data_Space(opt);
if (ptr + len > limit) { LogMsg("ERROR: putOptRData - out of space"); return mDNSNULL; }
for (opt = &rr->rdata->u.opt[0]; opt < end; opt++)
{
const int space = DNSOpt_Data_Space(opt);
ptr = putVal16(ptr, opt->opt);
ptr = putVal16(ptr, (mDNSu16)space - 4);
switch (opt->opt)
{
case kDNSOpt_LLQ:
ptr = putVal16(ptr, opt->u.llq.vers);
ptr = putVal16(ptr, opt->u.llq.llqOp);
ptr = putVal16(ptr, opt->u.llq.err);
mDNSPlatformMemCopy(ptr, opt->u.llq.id.b, 8); // 8-byte id
ptr += 8;
ptr = putVal32(ptr, opt->u.llq.llqlease);
break;
case kDNSOpt_Lease:
ptr = putVal32(ptr, opt->u.updatelease);
break;
case kDNSOpt_Owner:
*ptr++ = opt->u.owner.vers;
*ptr++ = opt->u.owner.seq;
mDNSPlatformMemCopy(ptr, opt->u.owner.HMAC.b, 6); // 6-byte Host identifier
ptr += 6;
if (space >= DNSOpt_OwnerData_ID_Wake_Space)
{
mDNSPlatformMemCopy(ptr, opt->u.owner.IMAC.b, 6); // 6-byte interface MAC
ptr += 6;
if (space > DNSOpt_OwnerData_ID_Wake_Space)
{
mDNSPlatformMemCopy(ptr, opt->u.owner.password.b, space - DNSOpt_OwnerData_ID_Wake_Space);
ptr += space - DNSOpt_OwnerData_ID_Wake_Space;
}
}
break;
}
}
return ptr;
}
case kDNSType_NSEC: {
// For our simplified use of NSEC synthetic records:
// nextname is always the record's own name,
// the block number is always 0,
// the count byte is a value in the range 1-32,
// followed by the 1-32 data bytes
int i, j;
for (i=sizeof(rdataNSEC); i>0; i--) if (rdb->nsec.bitmap[i-1]) break;
ptr = putDomainNameAsLabels(msg, ptr, limit, rr->name);
if (!ptr) return(mDNSNULL);
if (i) // Only put a block if at least one type exists for this name
{
if (ptr + 2 + i > limit) return(mDNSNULL);
*ptr++ = 0;
*ptr++ = (mDNSu8)i;
for (j=0; j<i; j++) *ptr++ = rdb->nsec.bitmap[j];
}
return ptr;
}
default: debugf("putRData: Warning! Writing unknown resource type %d as raw data", rr->rrtype);
if (ptr + rr->rdlength > limit) return(mDNSNULL);
mDNSPlatformMemCopy(ptr, rdb->data, rr->rdlength);
return(ptr + rr->rdlength);
}
}
#define IsUnicastUpdate(X) (!mDNSOpaque16IsZero((X)->h.id) && ((X)->h.flags.b[0] & kDNSFlag0_OP_Mask) == kDNSFlag0_OP_Update)
mDNSexport mDNSu8 *PutResourceRecordTTLWithLimit(DNSMessage *const msg, mDNSu8 *ptr, mDNSu16 *count, ResourceRecord *rr, mDNSu32 ttl, const mDNSu8 *limit)
{
mDNSu8 *endofrdata;
mDNSu16 actualLength;
// When sending SRV to conventional DNS server (i.e. in DNS update requests) we should not do name compression on the rdata (RFC 2782)
const DNSMessage *const rdatacompressionbase = (IsUnicastUpdate(msg) && rr->rrtype == kDNSType_SRV) ? mDNSNULL : msg;
if (rr->RecordType == kDNSRecordTypeUnregistered)
{
LogMsg("PutResourceRecord ERROR! Attempt to put kDNSRecordTypeUnregistered %##s (%s)", rr->name->c, DNSTypeName(rr->rrtype));
return(ptr);
}
if (!ptr) { LogMsg("PutResourceRecordTTLWithLimit ptr is null"); return(mDNSNULL); }
ptr = putDomainNameAsLabels(msg, ptr, limit, rr->name);
if (!ptr || ptr + 10 >= limit) return(mDNSNULL); // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rr->rrtype >> 8);
ptr[1] = (mDNSu8)(rr->rrtype & 0xFF);
ptr[2] = (mDNSu8)(rr->rrclass >> 8);
ptr[3] = (mDNSu8)(rr->rrclass & 0xFF);
ptr[4] = (mDNSu8)((ttl >> 24) & 0xFF);
ptr[5] = (mDNSu8)((ttl >> 16) & 0xFF);
ptr[6] = (mDNSu8)((ttl >> 8) & 0xFF);
ptr[7] = (mDNSu8)( ttl & 0xFF);
// ptr[8] and ptr[9] filled in *after* we find out how much space the rdata takes
endofrdata = putRData(rdatacompressionbase, ptr+10, limit, rr);
if (!endofrdata) { verbosedebugf("Ran out of space in PutResourceRecord for %##s (%s)", rr->name->c, DNSTypeName(rr->rrtype)); return(mDNSNULL); }
// Go back and fill in the actual number of data bytes we wrote
// (actualLength can be less than rdlength when domain name compression is used)
actualLength = (mDNSu16)(endofrdata - ptr - 10);
ptr[8] = (mDNSu8)(actualLength >> 8);
ptr[9] = (mDNSu8)(actualLength & 0xFF);
if (count) (*count)++;
else LogMsg("PutResourceRecordTTL: ERROR: No target count to update for %##s (%s)", rr->name->c, DNSTypeName(rr->rrtype));
return(endofrdata);
}
mDNSlocal mDNSu8 *putEmptyResourceRecord(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, mDNSu16 *count, const AuthRecord *rr)
{
ptr = putDomainNameAsLabels(msg, ptr, limit, rr->resrec.name);
if (!ptr || ptr + 10 > limit) return(mDNSNULL); // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rr->resrec.rrtype >> 8); // Put type
ptr[1] = (mDNSu8)(rr->resrec.rrtype & 0xFF);
ptr[2] = (mDNSu8)(rr->resrec.rrclass >> 8); // Put class
ptr[3] = (mDNSu8)(rr->resrec.rrclass & 0xFF);
ptr[4] = ptr[5] = ptr[6] = ptr[7] = 0; // TTL is zero
ptr[8] = ptr[9] = 0; // RDATA length is zero
(*count)++;
return(ptr + 10);
}
mDNSexport mDNSu8 *putQuestion(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name, mDNSu16 rrtype, mDNSu16 rrclass)
{
ptr = putDomainNameAsLabels(msg, ptr, limit, name);
if (!ptr || ptr+4 >= limit) return(mDNSNULL); // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rrtype >> 8);
ptr[1] = (mDNSu8)(rrtype & 0xFF);
ptr[2] = (mDNSu8)(rrclass >> 8);
ptr[3] = (mDNSu8)(rrclass & 0xFF);
msg->h.numQuestions++;
return(ptr+4);
}
// for dynamic updates
mDNSexport mDNSu8 *putZone(DNSMessage *const msg, mDNSu8 *ptr, mDNSu8 *limit, const domainname *zone, mDNSOpaque16 zoneClass)
{
ptr = putDomainNameAsLabels(msg, ptr, limit, zone);
if (!ptr || ptr + 4 > limit) return mDNSNULL; // If we're out-of-space, return NULL
*ptr++ = (mDNSu8)(kDNSType_SOA >> 8);
*ptr++ = (mDNSu8)(kDNSType_SOA & 0xFF);
*ptr++ = zoneClass.b[0];
*ptr++ = zoneClass.b[1];
msg->h.mDNS_numZones++;
return ptr;
}
// for dynamic updates
mDNSexport mDNSu8 *putPrereqNameNotInUse(const domainname *const name, DNSMessage *const msg, mDNSu8 *const ptr, mDNSu8 *const end)
{
AuthRecord prereq;
mDNS_SetupResourceRecord(&prereq, mDNSNULL, mDNSInterface_Any, kDNSQType_ANY, kStandardTTL, 0, AuthRecordAny, mDNSNULL, mDNSNULL);
AssignDomainName(&prereq.namestorage, name);
prereq.resrec.rrtype = kDNSQType_ANY;
prereq.resrec.rrclass = kDNSClass_NONE;
return putEmptyResourceRecord(msg, ptr, end, &msg->h.mDNS_numPrereqs, &prereq);
}
// for dynamic updates
mDNSexport mDNSu8 *putDeletionRecord(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr)
{
// deletion: specify record w/ TTL 0, class NONE
const mDNSu16 origclass = rr->rrclass;
rr->rrclass = kDNSClass_NONE;
ptr = PutResourceRecordTTLJumbo(msg, ptr, &msg->h.mDNS_numUpdates, rr, 0);
rr->rrclass = origclass;
return ptr;
}
// for dynamic updates
mDNSexport mDNSu8 *putDeletionRecordWithLimit(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr, mDNSu8 *limit)
{
// deletion: specify record w/ TTL 0, class NONE
const mDNSu16 origclass = rr->rrclass;
rr->rrclass = kDNSClass_NONE;
ptr = PutResourceRecordTTLWithLimit(msg, ptr, &msg->h.mDNS_numUpdates, rr, 0, limit);
rr->rrclass = origclass;
return ptr;
}
mDNSexport mDNSu8 *putDeleteRRSetWithLimit(DNSMessage *msg, mDNSu8 *ptr, const domainname *name, mDNSu16 rrtype, mDNSu8 *limit)
{
mDNSu16 class = kDNSQClass_ANY;
ptr = putDomainNameAsLabels(msg, ptr, limit, name);
if (!ptr || ptr + 10 >= limit) return mDNSNULL; // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rrtype >> 8);
ptr[1] = (mDNSu8)(rrtype & 0xFF);
ptr[2] = (mDNSu8)(class >> 8);
ptr[3] = (mDNSu8)(class & 0xFF);
ptr[4] = ptr[5] = ptr[6] = ptr[7] = 0; // zero ttl
ptr[8] = ptr[9] = 0; // zero rdlength/rdata
msg->h.mDNS_numUpdates++;
return ptr + 10;
}
// for dynamic updates
mDNSexport mDNSu8 *putDeleteAllRRSets(DNSMessage *msg, mDNSu8 *ptr, const domainname *name)
{
const mDNSu8 *limit = msg->data + AbsoluteMaxDNSMessageData;
mDNSu16 class = kDNSQClass_ANY;
mDNSu16 rrtype = kDNSQType_ANY;
ptr = putDomainNameAsLabels(msg, ptr, limit, name);
if (!ptr || ptr + 10 >= limit) return mDNSNULL; // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rrtype >> 8);
ptr[1] = (mDNSu8)(rrtype & 0xFF);
ptr[2] = (mDNSu8)(class >> 8);
ptr[3] = (mDNSu8)(class & 0xFF);
ptr[4] = ptr[5] = ptr[6] = ptr[7] = 0; // zero ttl
ptr[8] = ptr[9] = 0; // zero rdlength/rdata
msg->h.mDNS_numUpdates++;
return ptr + 10;
}
// for dynamic updates
mDNSexport mDNSu8 *putUpdateLease(DNSMessage *msg, mDNSu8 *end, mDNSu32 lease)
{
AuthRecord rr;
mDNS_SetupResourceRecord(&rr, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
rr.resrec.rrclass = NormalMaxDNSMessageData;
rr.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record
rr.resrec.rdestimate = sizeof(rdataOPT);
rr.resrec.rdata->u.opt[0].opt = kDNSOpt_Lease;
rr.resrec.rdata->u.opt[0].u.updatelease = lease;
end = PutResourceRecordTTLJumbo(msg, end, &msg->h.numAdditionals, &rr.resrec, 0);
if (!end) { LogMsg("ERROR: putUpdateLease - PutResourceRecordTTL"); return mDNSNULL; }
return end;
}
// for dynamic updates
mDNSexport mDNSu8 *putUpdateLeaseWithLimit(DNSMessage *msg, mDNSu8 *end, mDNSu32 lease, mDNSu8 *limit)
{
AuthRecord rr;
mDNS_SetupResourceRecord(&rr, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
rr.resrec.rrclass = NormalMaxDNSMessageData;
rr.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record
rr.resrec.rdestimate = sizeof(rdataOPT);
rr.resrec.rdata->u.opt[0].opt = kDNSOpt_Lease;
rr.resrec.rdata->u.opt[0].u.updatelease = lease;
end = PutResourceRecordTTLWithLimit(msg, end, &msg->h.numAdditionals, &rr.resrec, 0, limit);
if (!end) { LogMsg("ERROR: putUpdateLease - PutResourceRecordTTLWithLimit"); return mDNSNULL; }
return end;
}
mDNSexport mDNSu8 *putHINFO(const mDNS *const m, DNSMessage *const msg, mDNSu8 *end, DomainAuthInfo *authInfo, mDNSu8 *limit)
{
if (authInfo && authInfo->AutoTunnel)
{
AuthRecord hinfo;
mDNSu8 *h = hinfo.rdatastorage.u.data;
mDNSu16 len = 2 + m->HIHardware.c[0] + m->HISoftware.c[0];
mDNSu8 *newptr;
mDNS_SetupResourceRecord(&hinfo, mDNSNULL, mDNSInterface_Any, kDNSType_HINFO, 0, kDNSRecordTypeUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
AppendDomainLabel(&hinfo.namestorage, &m->hostlabel);
AppendDomainName (&hinfo.namestorage, &authInfo->domain);
hinfo.resrec.rroriginalttl = 0;
mDNSPlatformMemCopy(h, &m->HIHardware, 1 + (mDNSu32)m->HIHardware.c[0]);
h += 1 + (int)h[0];
mDNSPlatformMemCopy(h, &m->HISoftware, 1 + (mDNSu32)m->HISoftware.c[0]);
hinfo.resrec.rdlength = len;
hinfo.resrec.rdestimate = len;
newptr = PutResourceRecordTTLWithLimit(msg, end, &msg->h.numAdditionals, &hinfo.resrec, 0, limit);
return newptr;
}
else
return end;
}
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNS Message Parsing Functions
#endif
mDNSexport mDNSu32 DomainNameHashValue(const domainname *const name)
{
mDNSu32 sum = 0;
const mDNSu8 *c;
for (c = name->c; c[0] != 0 && c[1] != 0; c += 2)
{
sum += ((mDNSIsUpperCase(c[0]) ? c[0] + 'a' - 'A' : c[0]) << 8) |
(mDNSIsUpperCase(c[1]) ? c[1] + 'a' - 'A' : c[1]);
sum = (sum<<3) | (sum>>29);
}
if (c[0]) sum += ((mDNSIsUpperCase(c[0]) ? c[0] + 'a' - 'A' : c[0]) << 8);
return(sum);
}
mDNSexport void SetNewRData(ResourceRecord *const rr, RData *NewRData, mDNSu16 rdlength)
{
domainname *target;
if (NewRData)
{
rr->rdata = NewRData;
rr->rdlength = rdlength;
}
// Must not try to get target pointer until after updating rr->rdata
target = GetRRDomainNameTarget(rr);
rr->rdlength = GetRDLength(rr, mDNSfalse);
rr->rdestimate = GetRDLength(rr, mDNStrue);
rr->rdatahash = target ? DomainNameHashValue(target) : RDataHashValue(rr);
}
mDNSexport const mDNSu8 *skipDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end)
{
mDNSu16 total = 0;
if (ptr < (mDNSu8*)msg || ptr >= end)
{ debugf("skipDomainName: Illegal ptr not within packet boundaries"); return(mDNSNULL); }
while (1) // Read sequence of labels
{
const mDNSu8 len = *ptr++; // Read length of this label
if (len == 0) return(ptr); // If length is zero, that means this name is complete
switch (len & 0xC0)
{
case 0x00: if (ptr + len >= end) // Remember: expect at least one more byte for the root label
{ debugf("skipDomainName: Malformed domain name (overruns packet end)"); return(mDNSNULL); }
if (total + 1 + len >= MAX_DOMAIN_NAME) // Remember: expect at least one more byte for the root label
{ debugf("skipDomainName: Malformed domain name (more than 256 characters)"); return(mDNSNULL); }
ptr += len;
total += 1 + len;
break;
case 0x40: debugf("skipDomainName: Extended EDNS0 label types 0x%X not supported", len); return(mDNSNULL);
case 0x80: debugf("skipDomainName: Illegal label length 0x%X", len); return(mDNSNULL);
case 0xC0: return(ptr+1);
}
}
}
// Routine to fetch an FQDN from the DNS message, following compression pointers if necessary.
mDNSexport const mDNSu8 *getDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end,
domainname *const name)
{
const mDNSu8 *nextbyte = mDNSNULL; // Record where we got to before we started following pointers
mDNSu8 *np = name->c; // Name pointer
const mDNSu8 *const limit = np + MAX_DOMAIN_NAME; // Limit so we don't overrun buffer
if (ptr < (mDNSu8*)msg || ptr >= end)
{ debugf("getDomainName: Illegal ptr not within packet boundaries"); return(mDNSNULL); }
*np = 0; // Tentatively place the root label here (may be overwritten if we have more labels)
while (1) // Read sequence of labels
{
const mDNSu8 len = *ptr++; // Read length of this label
if (len == 0) break; // If length is zero, that means this name is complete
switch (len & 0xC0)
{
int i;
mDNSu16 offset;
case 0x00: if (ptr + len >= end) // Remember: expect at least one more byte for the root label
{ debugf("getDomainName: Malformed domain name (overruns packet end)"); return(mDNSNULL); }
if (np + 1 + len >= limit) // Remember: expect at least one more byte for the root label
{ debugf("getDomainName: Malformed domain name (more than 256 characters)"); return(mDNSNULL); }
*np++ = len;
for (i=0; i<len; i++) *np++ = *ptr++;
*np = 0; // Tentatively place the root label here (may be overwritten if we have more labels)
break;
case 0x40: debugf("getDomainName: Extended EDNS0 label types 0x%X not supported in name %##s", len, name->c);
return(mDNSNULL);
case 0x80: debugf("getDomainName: Illegal label length 0x%X in domain name %##s", len, name->c); return(mDNSNULL);
case 0xC0: offset = (mDNSu16)((((mDNSu16)(len & 0x3F)) << 8) | *ptr++);
if (!nextbyte) nextbyte = ptr; // Record where we got to before we started following pointers
ptr = (mDNSu8 *)msg + offset;
if (ptr < (mDNSu8*)msg || ptr >= end)
{ debugf("getDomainName: Illegal compression pointer not within packet boundaries"); return(mDNSNULL); }
if (*ptr & 0xC0)
{ debugf("getDomainName: Compression pointer must point to real label"); return(mDNSNULL); }
break;
}
}
if (nextbyte) return(nextbyte);
else return(ptr);
}
mDNSexport const mDNSu8 *skipResourceRecord(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end)
{
mDNSu16 pktrdlength;
ptr = skipDomainName(msg, ptr, end);
if (!ptr) { debugf("skipResourceRecord: Malformed RR name"); return(mDNSNULL); }
if (ptr + 10 > end) { debugf("skipResourceRecord: Malformed RR -- no type/class/ttl/len!"); return(mDNSNULL); }
pktrdlength = (mDNSu16)((mDNSu16)ptr[8] << 8 | ptr[9]);
ptr += 10;
if (ptr + pktrdlength > end) { debugf("skipResourceRecord: RDATA exceeds end of packet"); return(mDNSNULL); }
return(ptr + pktrdlength);
}
mDNSexport const mDNSu8 *GetLargeResourceRecord(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *ptr,
const mDNSu8 *end, const mDNSInterfaceID InterfaceID, mDNSu8 RecordType, LargeCacheRecord *const largecr)
{
CacheRecord *const rr = &largecr->r;
RDataBody2 *const rdb = (RDataBody2 *)rr->smallrdatastorage.data;
mDNSu16 pktrdlength;
if (largecr == &m->rec && m->rec.r.resrec.RecordType)
{
LogMsg("GetLargeResourceRecord: m->rec appears to be already in use for %s", CRDisplayString(m, &m->rec.r));
#if ForceAlerts
*(long*)0 = 0;
#endif
}
rr->next = mDNSNULL;
rr->resrec.name = &largecr->namestorage;
rr->NextInKAList = mDNSNULL;
rr->TimeRcvd = m ? m->timenow : 0;
rr->DelayDelivery = 0;
rr->NextRequiredQuery = m ? m->timenow : 0; // Will be updated to the real value when we call SetNextCacheCheckTimeForRecord()
rr->LastUsed = m ? m->timenow : 0;
rr->CRActiveQuestion = mDNSNULL;
rr->UnansweredQueries = 0;
rr->LastUnansweredTime= 0;
#if ENABLE_MULTI_PACKET_QUERY_SNOOPING
rr->MPUnansweredQ = 0;
rr->MPLastUnansweredQT= 0;
rr->MPUnansweredKA = 0;
rr->MPExpectingKA = mDNSfalse;
#endif
rr->NextInCFList = mDNSNULL;
rr->resrec.InterfaceID = InterfaceID;
rr->resrec.rDNSServer = mDNSNULL;
ptr = getDomainName(msg, ptr, end, &largecr->namestorage); // Will bail out correctly if ptr is NULL
if (!ptr) { debugf("GetLargeResourceRecord: Malformed RR name"); return(mDNSNULL); }
rr->resrec.namehash = DomainNameHashValue(rr->resrec.name);
if (ptr + 10 > end) { debugf("GetLargeResourceRecord: Malformed RR -- no type/class/ttl/len!"); return(mDNSNULL); }
rr->resrec.rrtype = (mDNSu16) ((mDNSu16)ptr[0] << 8 | ptr[1]);
rr->resrec.rrclass = (mDNSu16)(((mDNSu16)ptr[2] << 8 | ptr[3]) & kDNSClass_Mask);
rr->resrec.rroriginalttl = (mDNSu32) ((mDNSu32)ptr[4] << 24 | (mDNSu32)ptr[5] << 16 | (mDNSu32)ptr[6] << 8 | ptr[7]);
if (rr->resrec.rroriginalttl > 0x70000000UL / mDNSPlatformOneSecond && (mDNSs32)rr->resrec.rroriginalttl != -1)
rr->resrec.rroriginalttl = 0x70000000UL / mDNSPlatformOneSecond;
// Note: We don't have to adjust m->NextCacheCheck here -- this is just getting a record into memory for
// us to look at. If we decide to copy it into the cache, then we'll update m->NextCacheCheck accordingly.
pktrdlength = (mDNSu16)((mDNSu16)ptr[8] << 8 | ptr[9]);
// If mDNS record has cache-flush bit set, we mark it unique
// For uDNS records, all are implicitly deemed unique (a single DNS server is always
// authoritative for the entire RRSet), unless this is a truncated response
if (ptr[2] & (kDNSClass_UniqueRRSet >> 8) || (!InterfaceID && !(msg->h.flags.b[0] & kDNSFlag0_TC)))
RecordType |= kDNSRecordTypePacketUniqueMask;
ptr += 10;
if (ptr + pktrdlength > end) { debugf("GetLargeResourceRecord: RDATA exceeds end of packet"); return(mDNSNULL); }
end = ptr + pktrdlength; // Adjust end to indicate the end of the rdata for this resource record
rr->resrec.rdata = (RData*)&rr->smallrdatastorage;
rr->resrec.rdata->MaxRDLength = MaximumRDSize;
if (!RecordType) LogMsg("GetLargeResourceRecord: No RecordType for %##s", rr->resrec.name->c);
// IMPORTANT: Any record type we understand and unpack into a structure containing domainnames needs to have corresponding
// cases in SameRDataBody() and RDataHashValue() to do a semantic comparison (or checksum) of the structure instead of a blind
// bitwise memory compare (or sum). This is because a domainname is a fixed size structure holding variable-length data.
// Any bytes past the logical end of the name are undefined, and a blind bitwise memory compare may indicate that
// two domainnames are different when semantically they are the same name and it's only the unused bytes that differ.
if (rr->resrec.rrclass == kDNSQClass_ANY && pktrdlength == 0) // Used in update packets to mean "Delete An RRset" (RFC 2136)
rr->resrec.rdlength = 0;
else switch (rr->resrec.rrtype)
{
case kDNSType_A: if (pktrdlength != sizeof(mDNSv4Addr)) goto fail;
rdb->ipv4.b[0] = ptr[0];
rdb->ipv4.b[1] = ptr[1];
rdb->ipv4.b[2] = ptr[2];
rdb->ipv4.b[3] = ptr[3];
break;
case kDNSType_NS:
case kDNSType_CNAME:
case kDNSType_PTR:
case kDNSType_DNAME:ptr = getDomainName(msg, ptr, end, &rdb->name);
if (ptr != end) { debugf("GetLargeResourceRecord: Malformed CNAME/PTR RDATA name"); goto fail; }
//debugf("%##s PTR %##s rdlen %d", rr->resrec.name.c, rdb->name.c, pktrdlength);
break;
case kDNSType_SOA: ptr = getDomainName(msg, ptr, end, &rdb->soa.mname);
if (!ptr) { debugf("GetLargeResourceRecord: Malformed SOA RDATA mname"); goto fail; }
ptr = getDomainName(msg, ptr, end, &rdb->soa.rname);
if (!ptr) { debugf("GetLargeResourceRecord: Malformed SOA RDATA rname"); goto fail; }
if (ptr + 0x14 != end) { debugf("GetLargeResourceRecord: Malformed SOA RDATA"); goto fail; }
rdb->soa.serial = (mDNSs32) ((mDNSs32)ptr[0x00] << 24 | (mDNSs32)ptr[0x01] << 16 | (mDNSs32)ptr[0x02] << 8 | ptr[0x03]);
rdb->soa.refresh = (mDNSu32) ((mDNSu32)ptr[0x04] << 24 | (mDNSu32)ptr[0x05] << 16 | (mDNSu32)ptr[0x06] << 8 | ptr[0x07]);
rdb->soa.retry = (mDNSu32) ((mDNSu32)ptr[0x08] << 24 | (mDNSu32)ptr[0x09] << 16 | (mDNSu32)ptr[0x0A] << 8 | ptr[0x0B]);
rdb->soa.expire = (mDNSu32) ((mDNSu32)ptr[0x0C] << 24 | (mDNSu32)ptr[0x0D] << 16 | (mDNSu32)ptr[0x0E] << 8 | ptr[0x0F]);
rdb->soa.min = (mDNSu32) ((mDNSu32)ptr[0x10] << 24 | (mDNSu32)ptr[0x11] << 16 | (mDNSu32)ptr[0x12] << 8 | ptr[0x13]);
break;
case kDNSType_NULL:
case kDNSType_HINFO:
case kDNSType_TSIG:
case kDNSType_TXT:
case kDNSType_X25:
case kDNSType_ISDN:
case kDNSType_LOC:
case kDNSType_DHCID:if (pktrdlength > rr->resrec.rdata->MaxRDLength)
{
debugf("GetLargeResourceRecord: %s rdata size (%d) exceeds storage (%d)",
DNSTypeName(rr->resrec.rrtype), pktrdlength, rr->resrec.rdata->MaxRDLength);
goto fail;
}
rr->resrec.rdlength = pktrdlength;
mDNSPlatformMemCopy(rdb->data, ptr, pktrdlength);
break;
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: if (pktrdlength < 3) goto fail; // Preference + domainname
rdb->mx.preference = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
ptr = getDomainName(msg, ptr+2, end, &rdb->mx.exchange);
if (ptr != end) { debugf("GetLargeResourceRecord: Malformed MX name"); goto fail; }
//debugf("%##s SRV %##s rdlen %d", rr->resrec.name.c, rdb->srv.target.c, pktrdlength);
break;
case kDNSType_RP: ptr = getDomainName(msg, ptr, end, &rdb->rp.mbox); // Domainname + domainname
if (!ptr) { debugf("GetLargeResourceRecord: Malformed RP mbox"); goto fail; }
ptr = getDomainName(msg, ptr, end, &rdb->rp.txt);
if (ptr != end) { debugf("GetLargeResourceRecord: Malformed RP txt"); goto fail; }
break;
case kDNSType_PX: if (pktrdlength < 4) goto fail; // Preference + domainname + domainname
rdb->px.preference = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
ptr = getDomainName(msg, ptr, end, &rdb->px.map822);
if (!ptr) { debugf("GetLargeResourceRecord: Malformed PX map822"); goto fail; }
ptr = getDomainName(msg, ptr, end, &rdb->px.mapx400);
if (ptr != end) { debugf("GetLargeResourceRecord: Malformed PX mapx400"); goto fail; }
break;
case kDNSType_AAAA: if (pktrdlength != sizeof(mDNSv6Addr)) goto fail;
mDNSPlatformMemCopy(&rdb->ipv6, ptr, sizeof(rdb->ipv6));
break;
case kDNSType_SRV: if (pktrdlength < 7) goto fail; // Priority + weight + port + domainname
rdb->srv.priority = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
rdb->srv.weight = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]);
rdb->srv.port.b[0] = ptr[4];
rdb->srv.port.b[1] = ptr[5];
ptr = getDomainName(msg, ptr+6, end, &rdb->srv.target);
if (ptr != end) { debugf("GetLargeResourceRecord: Malformed SRV RDATA name"); goto fail; }
//debugf("%##s SRV %##s rdlen %d", rr->resrec.name.c, rdb->srv.target.c, pktrdlength);
break;
case kDNSType_OPT: {
rdataOPT *opt = rr->resrec.rdata->u.opt;
rr->resrec.rdlength = 0;
while (ptr < end && (mDNSu8 *)(opt+1) < &rr->resrec.rdata->u.data[MaximumRDSize])
{
const rdataOPT *const currentopt = opt;
if (ptr + 4 > end) { LogInfo("GetLargeResourceRecord: OPT RDATA ptr + 4 > end"); goto fail; }
opt->opt = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
opt->optlen = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]);
ptr += 4;
if (ptr + opt->optlen > end) { LogInfo("GetLargeResourceRecord: ptr + opt->optlen > end"); goto fail; }
switch (opt->opt)
{
case kDNSOpt_LLQ:
if (opt->optlen == DNSOpt_LLQData_Space - 4)
{
opt->u.llq.vers = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
opt->u.llq.llqOp = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]);
opt->u.llq.err = (mDNSu16)((mDNSu16)ptr[4] << 8 | ptr[5]);
mDNSPlatformMemCopy(opt->u.llq.id.b, ptr+6, 8);
opt->u.llq.llqlease = (mDNSu32) ((mDNSu32)ptr[14] << 24 | (mDNSu32)ptr[15] << 16 | (mDNSu32)ptr[16] << 8 | ptr[17]);
if (opt->u.llq.llqlease > 0x70000000UL / mDNSPlatformOneSecond)
opt->u.llq.llqlease = 0x70000000UL / mDNSPlatformOneSecond;
opt++;
}
break;
case kDNSOpt_Lease:
if (opt->optlen == DNSOpt_LeaseData_Space - 4)
{
opt->u.updatelease = (mDNSu32) ((mDNSu32)ptr[0] << 24 | (mDNSu32)ptr[1] << 16 | (mDNSu32)ptr[2] << 8 | ptr[3]);
if (opt->u.updatelease > 0x70000000UL / mDNSPlatformOneSecond)
opt->u.updatelease = 0x70000000UL / mDNSPlatformOneSecond;
opt++;
}
break;
case kDNSOpt_Owner:
if (ValidOwnerLength(opt->optlen))
{
opt->u.owner.vers = ptr[0];
opt->u.owner.seq = ptr[1];
mDNSPlatformMemCopy(opt->u.owner.HMAC.b, ptr+2, 6); // 6-byte MAC address
mDNSPlatformMemCopy(opt->u.owner.IMAC.b, ptr+2, 6); // 6-byte MAC address
opt->u.owner.password = zeroEthAddr;
if (opt->optlen >= DNSOpt_OwnerData_ID_Wake_Space-4)
{
mDNSPlatformMemCopy(opt->u.owner.IMAC.b, ptr+8, 6); // 6-byte MAC address
// This mDNSPlatformMemCopy is safe because the ValidOwnerLength(opt->optlen) check above
// ensures that opt->optlen is no more than DNSOpt_OwnerData_ID_Wake_PW6_Space - 4
if (opt->optlen > DNSOpt_OwnerData_ID_Wake_Space-4)
mDNSPlatformMemCopy(opt->u.owner.password.b, ptr+14, opt->optlen - (DNSOpt_OwnerData_ID_Wake_Space-4));
}
opt++;
}
break;
}
ptr += currentopt->optlen;
}
rr->resrec.rdlength = (mDNSu16)((mDNSu8*)opt - rr->resrec.rdata->u.data);
if (ptr != end) { LogInfo("GetLargeResourceRecord: Malformed OptRdata"); goto fail; }
break;
}
case kDNSType_NSEC: {
unsigned int i, j;
domainname d;
ptr = getDomainName(msg, ptr, end, &d); // Ignored for our simplified use of NSEC synthetic records
if (!ptr) { LogInfo("GetLargeResourceRecord: Malformed NSEC nextname"); goto fail; }
mDNSPlatformMemZero(rdb->nsec.bitmap, sizeof(rdb->nsec.bitmap));
if (ptr < end)
{
if (*ptr++ != 0) { debugf("GetLargeResourceRecord: We only handle block zero NSECs"); goto fail; }
i = *ptr++;
if (i > sizeof(rdataNSEC)) { debugf("GetLargeResourceRecord: invalid block length %d", i); goto fail; }
for (j=0; j<i; j++) rdb->nsec.bitmap[j] = *ptr++;
}
if (ptr != end) { debugf("GetLargeResourceRecord: Malformed NSEC"); goto fail; }
break;
}
default: if (pktrdlength > rr->resrec.rdata->MaxRDLength)
{
debugf("GetLargeResourceRecord: rdata %d (%s) size (%d) exceeds storage (%d)",
rr->resrec.rrtype, DNSTypeName(rr->resrec.rrtype), pktrdlength, rr->resrec.rdata->MaxRDLength);
goto fail;
}
debugf("GetLargeResourceRecord: Warning! Reading resource type %d (%s) as opaque data",
rr->resrec.rrtype, DNSTypeName(rr->resrec.rrtype));
// Note: Just because we don't understand the record type, that doesn't
// mean we fail. The DNS protocol specifies rdlength, so we can
// safely skip over unknown records and ignore them.
// We also grab a binary copy of the rdata anyway, since the caller
// might know how to interpret it even if we don't.
rr->resrec.rdlength = pktrdlength;
mDNSPlatformMemCopy(rdb->data, ptr, pktrdlength);
break;
}
SetNewRData(&rr->resrec, mDNSNULL, 0); // Sets rdlength, rdestimate, rdatahash for us
// Success! Now fill in RecordType to show this record contains valid data
rr->resrec.RecordType = RecordType;
return(end);
fail:
// If we were unable to parse the rdata in this record, we indicate that by
// returing a 'kDNSRecordTypePacketNegative' record with rdlength set to zero
rr->resrec.RecordType = kDNSRecordTypePacketNegative;
rr->resrec.rdlength = 0;
rr->resrec.rdestimate = 0;
rr->resrec.rdatahash = 0;
return(end);
}
mDNSexport const mDNSu8 *skipQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end)
{
ptr = skipDomainName(msg, ptr, end);
if (!ptr) { debugf("skipQuestion: Malformed domain name in DNS question section"); return(mDNSNULL); }
if (ptr+4 > end) { debugf("skipQuestion: Malformed DNS question section -- no query type and class!"); return(mDNSNULL); }
return(ptr+4);
}
mDNSexport const mDNSu8 *getQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end, const mDNSInterfaceID InterfaceID,
DNSQuestion *question)
{
mDNSPlatformMemZero(question, sizeof(*question));
question->InterfaceID = InterfaceID;
if (!InterfaceID) question->TargetQID = onesID; // In DNSQuestions we use TargetQID as the indicator of whether it's unicast or multicast
ptr = getDomainName(msg, ptr, end, &question->qname);
if (!ptr) { debugf("Malformed domain name in DNS question section"); return(mDNSNULL); }
if (ptr+4 > end) { debugf("Malformed DNS question section -- no query type and class!"); return(mDNSNULL); }
question->qnamehash = DomainNameHashValue(&question->qname);
question->qtype = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]); // Get type
question->qclass = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]); // and class
return(ptr+4);
}
mDNSexport const mDNSu8 *LocateAnswers(const DNSMessage *const msg, const mDNSu8 *const end)
{
int i;
const mDNSu8 *ptr = msg->data;
for (i = 0; i < msg->h.numQuestions && ptr; i++) ptr = skipQuestion(msg, ptr, end);
return(ptr);
}
mDNSexport const mDNSu8 *LocateAuthorities(const DNSMessage *const msg, const mDNSu8 *const end)
{
int i;
const mDNSu8 *ptr = LocateAnswers(msg, end);
for (i = 0; i < msg->h.numAnswers && ptr; i++) ptr = skipResourceRecord(msg, ptr, end);
return(ptr);
}
mDNSexport const mDNSu8 *LocateAdditionals(const DNSMessage *const msg, const mDNSu8 *const end)
{
int i;
const mDNSu8 *ptr = LocateAuthorities(msg, end);
for (i = 0; i < msg->h.numAuthorities; i++) ptr = skipResourceRecord(msg, ptr, end);
return (ptr);
}
mDNSexport const mDNSu8 *LocateOptRR(const DNSMessage *const msg, const mDNSu8 *const end, int minsize)
{
int i;
const mDNSu8 *ptr = LocateAdditionals(msg, end);
// Locate the OPT record.
// According to RFC 2671, "One OPT pseudo-RR can be added to the additional data section of either a request or a response."
// This implies that there may be *at most* one OPT record per DNS message, in the Additional Section,
// but not necessarily the *last* entry in the Additional Section.
for (i = 0; ptr && i < msg->h.numAdditionals; i++)
{
if (ptr + DNSOpt_Header_Space + minsize <= end && // Make sure we have 11+minsize bytes of data
ptr[0] == 0 && // Name must be root label
ptr[1] == (kDNSType_OPT >> 8 ) && // rrtype OPT
ptr[2] == (kDNSType_OPT & 0xFF) &&
((mDNSu16)ptr[9] << 8 | (mDNSu16)ptr[10]) >= (mDNSu16)minsize)
return(ptr);
else
ptr = skipResourceRecord(msg, ptr, end);
}
return(mDNSNULL);
}
// On success, GetLLQOptData returns pointer to storage within shared "m->rec";
// it is caller's responsibilty to clear m->rec.r.resrec.RecordType after use
// Note: An OPT RDataBody actually contains one or more variable-length rdataOPT objects packed together
// The code that currently calls this assumes there's only one, instead of iterating through the set
mDNSexport const rdataOPT *GetLLQOptData(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end)
{
const mDNSu8 *ptr = LocateOptRR(msg, end, DNSOpt_LLQData_Space);
if (ptr)
{
ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec);
if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative) return(&m->rec.r.resrec.rdata->u.opt[0]);
}
return(mDNSNULL);
}
// Get the lease life of records in a dynamic update
// returns 0 on error or if no lease present
mDNSexport mDNSu32 GetPktLease(mDNS *m, DNSMessage *msg, const mDNSu8 *end)
{
mDNSu32 result = 0;
const mDNSu8 *ptr = LocateOptRR(msg, end, DNSOpt_LeaseData_Space);
if (ptr) ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec);
if (ptr && m->rec.r.resrec.rdlength >= DNSOpt_LeaseData_Space && m->rec.r.resrec.rdata->u.opt[0].opt == kDNSOpt_Lease)
result = m->rec.r.resrec.rdata->u.opt[0].u.updatelease;
m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it
return(result);
}
mDNSlocal const mDNSu8 *DumpRecords(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end, int count, char *label)
{
int i;
LogMsg("%2d %s", count, label);
for (i = 0; i < count && ptr; i++)
{
// This puts a LargeCacheRecord on the stack instead of using the shared m->rec storage,
// but since it's only used for debugging (and probably only on OS X, not on
// embedded systems) putting a 9kB object on the stack isn't a big problem.
LargeCacheRecord largecr;
ptr = GetLargeResourceRecord(m, msg, ptr, end, mDNSInterface_Any, kDNSRecordTypePacketAns, &largecr);
if (ptr) LogMsg("%2d TTL%8d %s", i, largecr.r.resrec.rroriginalttl, CRDisplayString(m, &largecr.r));
}
if (!ptr) LogMsg("ERROR: Premature end of packet data");
return(ptr);
}
#define DNS_OP_Name(X) ( \
(X) == kDNSFlag0_OP_StdQuery ? "" : \
(X) == kDNSFlag0_OP_Iquery ? "Iquery " : \
(X) == kDNSFlag0_OP_Status ? "Status " : \
(X) == kDNSFlag0_OP_Unused3 ? "Unused3 " : \
(X) == kDNSFlag0_OP_Notify ? "Notify " : \
(X) == kDNSFlag0_OP_Update ? "Update " : "?? " )
#define DNS_RC_Name(X) ( \
(X) == kDNSFlag1_RC_NoErr ? "NoErr" : \
(X) == kDNSFlag1_RC_FormErr ? "FormErr" : \
(X) == kDNSFlag1_RC_ServFail ? "ServFail" : \
(X) == kDNSFlag1_RC_NXDomain ? "NXDomain" : \
(X) == kDNSFlag1_RC_NotImpl ? "NotImpl" : \
(X) == kDNSFlag1_RC_Refused ? "Refused" : \
(X) == kDNSFlag1_RC_YXDomain ? "YXDomain" : \
(X) == kDNSFlag1_RC_YXRRSet ? "YXRRSet" : \
(X) == kDNSFlag1_RC_NXRRSet ? "NXRRSet" : \
(X) == kDNSFlag1_RC_NotAuth ? "NotAuth" : \
(X) == kDNSFlag1_RC_NotZone ? "NotZone" : "??" )
// Note: DumpPacket expects the packet header fields in host byte order, not network byte order
mDNSexport void DumpPacket(mDNS *const m, mStatus status, mDNSBool sent, char *transport,
const mDNSAddr *srcaddr, mDNSIPPort srcport,
const mDNSAddr *dstaddr, mDNSIPPort dstport, const DNSMessage *const msg, const mDNSu8 *const end)
{
mDNSBool IsUpdate = ((msg->h.flags.b[0] & kDNSFlag0_OP_Mask) == kDNSFlag0_OP_Update);
const mDNSu8 *ptr = msg->data;
int i;
DNSQuestion q;
char tbuffer[64], sbuffer[64], dbuffer[64] = "";
if (!status) tbuffer[mDNS_snprintf(tbuffer, sizeof(tbuffer), sent ? "Sent" : "Received" )] = 0;
else tbuffer[mDNS_snprintf(tbuffer, sizeof(tbuffer), "ERROR %d %sing", status, sent ? "Send" : "Receiv")] = 0;
if (sent) sbuffer[mDNS_snprintf(sbuffer, sizeof(sbuffer), "port " )] = 0;
else sbuffer[mDNS_snprintf(sbuffer, sizeof(sbuffer), "%#a:", srcaddr)] = 0;
if (dstaddr || !mDNSIPPortIsZero(dstport))
dbuffer[mDNS_snprintf(dbuffer, sizeof(dbuffer), " to %#a:%d", dstaddr, mDNSVal16(dstport))] = 0;
LogMsg("-- %s %s DNS %s%s (flags %02X%02X) RCODE: %s (%d) %s%s%s%s%s%sID: %d %d bytes from %s%d%s%s --",
tbuffer, transport,
DNS_OP_Name(msg->h.flags.b[0] & kDNSFlag0_OP_Mask),
msg->h.flags.b[0] & kDNSFlag0_QR_Response ? "Response" : "Query",
msg->h.flags.b[0], msg->h.flags.b[1],
DNS_RC_Name(msg->h.flags.b[1] & kDNSFlag1_RC_Mask),
msg->h.flags.b[1] & kDNSFlag1_RC_Mask,
msg->h.flags.b[0] & kDNSFlag0_AA ? "AA " : "",
msg->h.flags.b[0] & kDNSFlag0_TC ? "TC " : "",
msg->h.flags.b[0] & kDNSFlag0_RD ? "RD " : "",
msg->h.flags.b[1] & kDNSFlag1_RA ? "RA " : "",
msg->h.flags.b[1] & kDNSFlag1_AD ? "AD " : "",
msg->h.flags.b[1] & kDNSFlag1_CD ? "CD " : "",
mDNSVal16(msg->h.id),
end - msg->data,
sbuffer, mDNSVal16(srcport), dbuffer,
(msg->h.flags.b[0] & kDNSFlag0_TC) ? " (truncated)" : ""
);
LogMsg("%2d %s", msg->h.numQuestions, IsUpdate ? "Zone" : "Questions");
for (i = 0; i < msg->h.numQuestions && ptr; i++)
{
ptr = getQuestion(msg, ptr, end, mDNSInterface_Any, &q);
if (ptr) LogMsg("%2d %##s %s", i, q.qname.c, DNSTypeName(q.qtype));
}
ptr = DumpRecords(m, msg, ptr, end, msg->h.numAnswers, IsUpdate ? "Prerequisites" : "Answers");
ptr = DumpRecords(m, msg, ptr, end, msg->h.numAuthorities, IsUpdate ? "Updates" : "Authorities");
ptr = DumpRecords(m, msg, ptr, end, msg->h.numAdditionals, "Additionals");
LogMsg("--------------");
}
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Packet Sending Functions
#endif
// Stub definition of TCPSocket_struct so we can access flags field. (Rest of TCPSocket_struct is platform-dependent.)
struct TCPSocket_struct { TCPSocketFlags flags; /* ... */ };
struct UDPSocket_struct
{
mDNSIPPort port; // MUST BE FIRST FIELD -- mDNSCoreReceive expects every UDPSocket_struct to begin with mDNSIPPort port
};
// Note: When we sign a DNS message using DNSDigest_SignMessage(), the current real-time clock value is used, which
// is why we generally defer signing until we send the message, to ensure the signature is as fresh as possible.
mDNSexport mStatus mDNSSendDNSMessage(mDNS *const m, DNSMessage *const msg, mDNSu8 *end,
mDNSInterfaceID InterfaceID, UDPSocket *src, const mDNSAddr *dst, mDNSIPPort dstport, TCPSocket *sock, DomainAuthInfo *authInfo)
{
mStatus status = mStatus_NoError;
const mDNSu16 numAdditionals = msg->h.numAdditionals;
mDNSu8 *newend;
mDNSu8 *limit = msg->data + AbsoluteMaxDNSMessageData;
// Zero-length message data is okay (e.g. for a DNS Update ack, where all we need is an ID and an error code
if (end < msg->data || end - msg->data > AbsoluteMaxDNSMessageData)
{
LogMsg("mDNSSendDNSMessage: invalid message %p %p %d", msg->data, end, end - msg->data);
return mStatus_BadParamErr;
}
newend = putHINFO(m, msg, end, authInfo, limit);
if (!newend) LogMsg("mDNSSendDNSMessage: putHINFO failed msg %p end %p, limit %p", msg->data, end, limit); // Not fatal
else end = newend;
// Put all the integer values in IETF byte-order (MSB first, LSB second)
SwapDNSHeaderBytes(msg);
if (authInfo) DNSDigest_SignMessage(msg, &end, authInfo, 0); // DNSDigest_SignMessage operates on message in network byte order
if (!end) { LogMsg("mDNSSendDNSMessage: DNSDigest_SignMessage failed"); status = mStatus_NoMemoryErr; }
else
{
// Send the packet on the wire
if (!sock)
status = mDNSPlatformSendUDP(m, msg, end, InterfaceID, src, dst, dstport);
else
{
mDNSu16 msglen = (mDNSu16)(end - (mDNSu8 *)msg);
mDNSu8 lenbuf[2] = { (mDNSu8)(msglen >> 8), (mDNSu8)(msglen & 0xFF) };
long nsent = mDNSPlatformWriteTCP(sock, (char*)lenbuf, 2); // Should do scatter/gather here -- this is probably going out as two packets
if (nsent != 2) { LogMsg("mDNSSendDNSMessage: write msg length failed %d/%d", nsent, 2); status = mStatus_ConnFailed; }
else
{
nsent = mDNSPlatformWriteTCP(sock, (char *)msg, msglen);
if (nsent != msglen) { LogMsg("mDNSSendDNSMessage: write msg body failed %d/%d", nsent, msglen); status = mStatus_ConnFailed; }
}
}
}
// Swap the integer values back the way they were (remember that numAdditionals may have been changed by putHINFO and/or SignMessage)
SwapDNSHeaderBytes(msg);
// Dump the packet with the HINFO and TSIG
if (mDNS_PacketLoggingEnabled && !mDNSOpaque16IsZero(msg->h.id))
DumpPacket(m, status, mDNStrue, sock && (sock->flags & kTCPSocketFlags_UseTLS) ? "TLS" : sock ? "TCP" : "UDP", mDNSNULL, src ? src->port : MulticastDNSPort, dst, dstport, msg, end);
// put the number of additionals back the way it was
msg->h.numAdditionals = numAdditionals;
return(status);
}
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - RR List Management & Task Management
#endif
mDNSexport void mDNS_Lock_(mDNS *const m, const char * const functionname)
{
// MUST grab the platform lock FIRST!
mDNSPlatformLock(m);
// Normally, mDNS_reentrancy is zero and so is mDNS_busy
// However, when we call a client callback mDNS_busy is one, and we increment mDNS_reentrancy too
// If that client callback does mDNS API calls, mDNS_reentrancy and mDNS_busy will both be one
// If mDNS_busy != mDNS_reentrancy that's a bad sign
if (m->mDNS_busy != m->mDNS_reentrancy)
{
LogMsg("%s: mDNS_Lock: Locking failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", functionname, m->mDNS_busy, m->mDNS_reentrancy);
#if ForceAlerts
*(long*)0 = 0;
#endif
}
// If this is an initial entry into the mDNSCore code, set m->timenow
// else, if this is a re-entrant entry into the mDNSCore code, m->timenow should already be set
if (m->mDNS_busy == 0)
{
if (m->timenow)
LogMsg("%s: mDNS_Lock: m->timenow already set (%ld/%ld)", functionname, m->timenow, mDNS_TimeNow_NoLock(m));
m->timenow = mDNS_TimeNow_NoLock(m);
if (m->timenow == 0) m->timenow = 1;
}
else if (m->timenow == 0)
{
LogMsg("%s: mDNS_Lock: m->mDNS_busy is %ld but m->timenow not set", functionname, m->mDNS_busy);
m->timenow = mDNS_TimeNow_NoLock(m);
if (m->timenow == 0) m->timenow = 1;
}
if (m->timenow_last - m->timenow > 0)
{
m->timenow_adjust += m->timenow_last - m->timenow;
LogMsg("%s: mDNSPlatformRawTime went backwards by %ld ticks; setting correction factor to %ld", functionname, m->timenow_last - m->timenow, m->timenow_adjust);
m->timenow = m->timenow_last;
}
m->timenow_last = m->timenow;
// Increment mDNS_busy so we'll recognise re-entrant calls
m->mDNS_busy++;
}
mDNSlocal AuthRecord *AnyLocalRecordReady(const mDNS *const m)
{
AuthRecord *rr;
for (rr = m->NewLocalRecords; rr; rr = rr->next)
if (LocalRecordReady(rr)) return rr;
return mDNSNULL;
}
mDNSlocal mDNSs32 GetNextScheduledEvent(const mDNS *const m)
{
mDNSs32 e = m->timenow + 0x78000000;
if (m->mDNSPlatformStatus != mStatus_NoError) return(e);
if (m->NewQuestions)
{
if (m->NewQuestions->DelayAnswering) e = m->NewQuestions->DelayAnswering;
else return(m->timenow);
}
if (m->NewLocalOnlyQuestions) return(m->timenow);
if (m->NewLocalRecords && AnyLocalRecordReady(m)) return(m->timenow);
if (m->NewLocalOnlyRecords) return(m->timenow);
if (m->SPSProxyListChanged) return(m->timenow);
if (m->LocalRemoveEvents) return(m->timenow);
#ifndef UNICAST_DISABLED
if (e - m->NextuDNSEvent > 0) e = m->NextuDNSEvent;
if (e - m->NextScheduledNATOp > 0) e = m->NextScheduledNATOp;
if (m->NextSRVUpdate && e - m->NextSRVUpdate > 0) e = m->NextSRVUpdate;
#endif
if (e - m->NextCacheCheck > 0) e = m->NextCacheCheck;
if (e - m->NextScheduledSPS > 0) e = m->NextScheduledSPS;
// NextScheduledSPRetry only valid when DelaySleep not set
if (!m->DelaySleep && m->SleepLimit && e - m->NextScheduledSPRetry > 0) e = m->NextScheduledSPRetry;
if (m->DelaySleep && e - m->DelaySleep > 0) e = m->DelaySleep;
if (m->SuppressSending)
{
if (e - m->SuppressSending > 0) e = m->SuppressSending;
}
else
{
if (e - m->NextScheduledQuery > 0) e = m->NextScheduledQuery;
if (e - m->NextScheduledProbe > 0) e = m->NextScheduledProbe;
if (e - m->NextScheduledResponse > 0) e = m->NextScheduledResponse;
}
if (e - m->NextScheduledStopTime > 0) e = m->NextScheduledStopTime;
return(e);
}
mDNSexport void ShowTaskSchedulingError(mDNS *const m)
{
AuthRecord *rr;
mDNS_Lock(m);
LogMsg("Task Scheduling Error: Continuously busy for more than a second");
// Note: To accurately diagnose *why* we're busy, the debugging code here needs to mirror the logic in GetNextScheduledEvent above
if (m->NewQuestions && (!m->NewQuestions->DelayAnswering || m->timenow - m->NewQuestions->DelayAnswering >= 0))
LogMsg("Task Scheduling Error: NewQuestion %##s (%s)",
m->NewQuestions->qname.c, DNSTypeName(m->NewQuestions->qtype));
if (m->NewLocalOnlyQuestions)
LogMsg("Task Scheduling Error: NewLocalOnlyQuestions %##s (%s)",
m->NewLocalOnlyQuestions->qname.c, DNSTypeName(m->NewLocalOnlyQuestions->qtype));
if (m->NewLocalRecords)
{
rr = AnyLocalRecordReady(m);
if (rr) LogMsg("Task Scheduling Error: NewLocalRecords %s", ARDisplayString(m, rr));
}
if (m->NewLocalOnlyRecords) LogMsg("Task Scheduling Error: NewLocalOnlyRecords");
if (m->SPSProxyListChanged) LogMsg("Task Scheduling Error: SPSProxyListChanged");
if (m->LocalRemoveEvents) LogMsg("Task Scheduling Error: LocalRemoveEvents");
if (m->timenow - m->NextScheduledEvent >= 0)
LogMsg("Task Scheduling Error: m->NextScheduledEvent %d", m->timenow - m->NextScheduledEvent);
#ifndef UNICAST_DISABLED
if (m->timenow - m->NextuDNSEvent >= 0)
LogMsg("Task Scheduling Error: m->NextuDNSEvent %d", m->timenow - m->NextuDNSEvent);
if (m->timenow - m->NextScheduledNATOp >= 0)
LogMsg("Task Scheduling Error: m->NextScheduledNATOp %d", m->timenow - m->NextScheduledNATOp);
if (m->NextSRVUpdate && m->timenow - m->NextSRVUpdate >= 0)
LogMsg("Task Scheduling Error: m->NextSRVUpdate %d", m->timenow - m->NextSRVUpdate);
#endif
if (m->timenow - m->NextCacheCheck >= 0)
LogMsg("Task Scheduling Error: m->NextCacheCheck %d", m->timenow - m->NextCacheCheck);
if (m->timenow - m->NextScheduledSPS >= 0)
LogMsg("Task Scheduling Error: m->NextScheduledSPS %d", m->timenow - m->NextScheduledSPS);
if (!m->DelaySleep && m->SleepLimit && m->timenow - m->NextScheduledSPRetry >= 0)
LogMsg("Task Scheduling Error: m->NextScheduledSPRetry %d", m->timenow - m->NextScheduledSPRetry);
if (m->DelaySleep && m->timenow - m->DelaySleep >= 0)
LogMsg("Task Scheduling Error: m->DelaySleep %d", m->timenow - m->DelaySleep);
if (m->SuppressSending && m->timenow - m->SuppressSending >= 0)
LogMsg("Task Scheduling Error: m->SuppressSending %d", m->timenow - m->SuppressSending);
if (m->timenow - m->NextScheduledQuery >= 0)
LogMsg("Task Scheduling Error: m->NextScheduledQuery %d", m->timenow - m->NextScheduledQuery);
if (m->timenow - m->NextScheduledProbe >= 0)
LogMsg("Task Scheduling Error: m->NextScheduledProbe %d", m->timenow - m->NextScheduledProbe);
if (m->timenow - m->NextScheduledResponse >= 0)
LogMsg("Task Scheduling Error: m->NextScheduledResponse %d", m->timenow - m->NextScheduledResponse);
mDNS_Unlock(m);
}
mDNSexport void mDNS_Unlock_(mDNS *const m, const char * const functionname)
{
// Decrement mDNS_busy
m->mDNS_busy--;
// Check for locking failures
if (m->mDNS_busy != m->mDNS_reentrancy)
{
LogMsg("%s: mDNS_Unlock: Locking failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", functionname, m->mDNS_busy, m->mDNS_reentrancy);
#if ForceAlerts
*(long*)0 = 0;
#endif
}
// If this is a final exit from the mDNSCore code, set m->NextScheduledEvent and clear m->timenow
if (m->mDNS_busy == 0)
{
m->NextScheduledEvent = GetNextScheduledEvent(m);
if (m->timenow == 0) LogMsg("%s: mDNS_Unlock: ERROR! m->timenow aready zero", functionname);
m->timenow = 0;
}
// MUST release the platform lock LAST!
mDNSPlatformUnlock(m);
}
// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Specialized mDNS version of vsnprintf
#endif
static const struct mDNSprintf_format
{
unsigned leftJustify : 1;
unsigned forceSign : 1;
unsigned zeroPad : 1;
unsigned havePrecision : 1;
unsigned hSize : 1;
unsigned lSize : 1;
char altForm;
char sign; // +, - or space
unsigned int fieldWidth;
unsigned int precision;
} mDNSprintf_format_default = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
mDNSexport mDNSu32 mDNS_vsnprintf(char *sbuffer, mDNSu32 buflen, const char *fmt, va_list arg)
{
mDNSu32 nwritten = 0;
int c;
if (buflen == 0) return(0);
buflen--; // Pre-reserve one space in the buffer for the terminating null
if (buflen == 0) goto exit;
for (c = *fmt; c != 0; c = *++fmt)
{
if (c != '%')
{
*sbuffer++ = (char)c;
if (++nwritten >= buflen) goto exit;
}
else
{
unsigned int i=0, j;
// The mDNS Vsprintf Argument Conversion Buffer is used as a temporary holding area for
// generating decimal numbers, hexdecimal numbers, IP addresses, domain name strings, etc.
// The size needs to be enough for a 256-byte domain name plus some error text.
#define mDNS_VACB_Size 300
char mDNS_VACB[mDNS_VACB_Size];
#define mDNS_VACB_Lim (&mDNS_VACB[mDNS_VACB_Size])
#define mDNS_VACB_Remain(s) ((mDNSu32)(mDNS_VACB_Lim - s))
char *s = mDNS_VACB_Lim, *digits;
struct mDNSprintf_format F = mDNSprintf_format_default;
while (1) // decode flags
{
c = *++fmt;
if (c == '-') F.leftJustify = 1;
else if (c == '+') F.forceSign = 1;
else if (c == ' ') F.sign = ' ';
else if (c == '#') F.altForm++;
else if (c == '0') F.zeroPad = 1;
else break;
}
if (c == '*') // decode field width
{
int f = va_arg(arg, int);
if (f < 0) { f = -f; F.leftJustify = 1; }
F.fieldWidth = (unsigned int)f;
c = *++fmt;
}
else
{
for (; c >= '0' && c <= '9'; c = *++fmt)
F.fieldWidth = (10 * F.fieldWidth) + (c - '0');
}
if (c == '.') // decode precision
{
if ((c = *++fmt) == '*')
{ F.precision = va_arg(arg, unsigned int); c = *++fmt; }
else for (; c >= '0' && c <= '9'; c = *++fmt)
F.precision = (10 * F.precision) + (c - '0');
F.havePrecision = 1;
}
if (F.leftJustify) F.zeroPad = 0;
conv:
switch (c) // perform appropriate conversion
{
unsigned long n;
case 'h' : F.hSize = 1; c = *++fmt; goto conv;
case 'l' : // fall through
case 'L' : F.lSize = 1; c = *++fmt; goto conv;
case 'd' :
case 'i' : if (F.lSize) n = (unsigned long)va_arg(arg, long);
else n = (unsigned long)va_arg(arg, int);
if (F.hSize) n = (short) n;
if ((long) n < 0) { n = (unsigned long)-(long)n; F.sign = '-'; }
else if (F.forceSign) F.sign = '+';
goto decimal;
case 'u' : if (F.lSize) n = va_arg(arg, unsigned long);
else n = va_arg(arg, unsigned int);
if (F.hSize) n = (unsigned short) n;
F.sign = 0;
goto decimal;
decimal: if (!F.havePrecision)
{
if (F.zeroPad)
{
F.precision = F.fieldWidth;
if (F.sign) --F.precision;
}
if (F.precision < 1) F.precision = 1;
}
if (F.precision > mDNS_VACB_Size - 1)
F.precision = mDNS_VACB_Size - 1;
for (i = 0; n; n /= 10, i++) *--s = (char)(n % 10 + '0');
for (; i < F.precision; i++) *--s = '0';
if (F.sign) { *--s = F.sign; i++; }
break;
case 'o' : if (F.lSize) n = va_arg(arg, unsigned long);
else n = va_arg(arg, unsigned int);
if (F.hSize) n = (unsigned short) n;
if (!F.havePrecision)
{
if (F.zeroPad) F.precision = F.fieldWidth;
if (F.precision < 1) F.precision = 1;
}
if (F.precision > mDNS_VACB_Size - 1)
F.precision = mDNS_VACB_Size - 1;
for (i = 0; n; n /= 8, i++) *--s = (char)(n % 8 + '0');
if (F.altForm && i && *s != '0') { *--s = '0'; i++; }
for (; i < F.precision; i++) *--s = '0';
break;
case 'a' : {
unsigned char *a = va_arg(arg, unsigned char *);
if (!a) { static char emsg[] = "<<NULL>>"; s = emsg; i = sizeof(emsg)-1; }
else
{
s = mDNS_VACB; // Adjust s to point to the start of the buffer, not the end
if (F.altForm)
{
mDNSAddr *ip = (mDNSAddr*)a;
switch (ip->type)
{
case mDNSAddrType_IPv4: F.precision = 4; a = (unsigned char *)&ip->ip.v4; break;
case mDNSAddrType_IPv6: F.precision = 16; a = (unsigned char *)&ip->ip.v6; break;
default: F.precision = 0; break;
}
}
if (F.altForm && !F.precision)
i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "«ZERO ADDRESS»");
else switch (F.precision)
{
case 4: i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "%d.%d.%d.%d",
a[0], a[1], a[2], a[3]); break;
case 6: i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "%02X:%02X:%02X:%02X:%02X:%02X",
a[0], a[1], a[2], a[3], a[4], a[5]); break;
case 16: i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB),
"%02X%02X:%02X%02X:%02X%02X:%02X%02X:%02X%02X:%02X%02X:%02X%02X:%02X%02X",
a[0x0], a[0x1], a[0x2], a[0x3], a[0x4], a[0x5], a[0x6], a[0x7],
a[0x8], a[0x9], a[0xA], a[0xB], a[0xC], a[0xD], a[0xE], a[0xF]); break;
default: i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "%s", "<< ERROR: Must specify"
" address size (i.e. %.4a=IPv4, %.6a=Ethernet, %.16a=IPv6) >>"); break;
}
}
}
break;
case 'p' : F.havePrecision = F.lSize = 1;
F.precision = sizeof(void*) * 2; // 8 characters on 32-bit; 16 characters on 64-bit
case 'X' : digits = "0123456789ABCDEF";
goto hexadecimal;
case 'x' : digits = "0123456789abcdef";
hexadecimal:if (F.lSize) n = va_arg(arg, unsigned long);
else n = va_arg(arg, unsigned int);
if (F.hSize) n = (unsigned short) n;
if (!F.havePrecision)
{
if (F.zeroPad)
{
F.precision = F.fieldWidth;
if (F.altForm) F.precision -= 2;
}
if (F.precision < 1) F.precision = 1;
}
if (F.precision > mDNS_VACB_Size - 1)
F.precision = mDNS_VACB_Size - 1;
for (i = 0; n; n /= 16, i++) *--s = digits[n % 16];
for (; i < F.precision; i++) *--s = '0';
if (F.altForm) { *--s = (char)c; *--s = '0'; i += 2; }
break;
case 'c' : *--s = (char)va_arg(arg, int); i = 1; break;
case 's' : s = va_arg(arg, char *);
if (!s) { static char emsg[] = "<<NULL>>"; s = emsg; i = sizeof(emsg)-1; }
else switch (F.altForm)
{
case 0: i=0;
if (!F.havePrecision) // C string
while (s[i]) i++;
else
{
while ((i < F.precision) && s[i]) i++;
// Make sure we don't truncate in the middle of a UTF-8 character
// If last character we got was any kind of UTF-8 multi-byte character,
// then see if we have to back up.
// This is not as easy as the similar checks below, because
// here we can't assume it's safe to examine the *next* byte, so we
// have to confine ourselves to working only backwards in the string.
j = i; // Record where we got to
// Now, back up until we find first non-continuation-char
while (i>0 && (s[i-1] & 0xC0) == 0x80) i--;
// Now s[i-1] is the first non-continuation-char
// and (j-i) is the number of continuation-chars we found
if (i>0 && (s[i-1] & 0xC0) == 0xC0) // If we found a start-char
{
i--; // Tentatively eliminate this start-char as well
// Now (j-i) is the number of characters we're considering eliminating.
// To be legal UTF-8, the start-char must contain (j-i) one-bits,
// followed by a zero bit. If we shift it right by (7-(j-i)) bits
// (with sign extension) then the result has to be 0xFE.
// If this is right, then we reinstate the tentatively eliminated bytes.
if (((j-i) < 7) && (((s[i] >> (7-(j-i))) & 0xFF) == 0xFE)) i = j;
}
}
break;
case 1: i = (unsigned char) *s++; break; // Pascal string
case 2: { // DNS label-sequence name
unsigned char *a = (unsigned char *)s;
s = mDNS_VACB; // Adjust s to point to the start of the buffer, not the end
if (*a == 0) *s++ = '.'; // Special case for root DNS name
while (*a)
{
char buf[63*4+1];
if (*a > 63)
{ s += mDNS_snprintf(s, mDNS_VACB_Remain(s), "<<INVALID LABEL LENGTH %u>>", *a); break; }
if (s + *a >= &mDNS_VACB[254])
{ s += mDNS_snprintf(s, mDNS_VACB_Remain(s), "<<NAME TOO LONG>>"); break; }
// Need to use ConvertDomainLabelToCString to do proper escaping here,
// so it's clear what's a literal dot and what's a label separator
ConvertDomainLabelToCString((domainlabel*)a, buf);
s += mDNS_snprintf(s, mDNS_VACB_Remain(s), "%s.", buf);
a += 1 + *a;
}
i = (mDNSu32)(s - mDNS_VACB);
s = mDNS_VACB; // Reset s back to the start of the buffer
break;
}
}
// Make sure we don't truncate in the middle of a UTF-8 character (see similar comment below)
if (F.havePrecision && i > F.precision)
{ i = F.precision; while (i>0 && (s[i] & 0xC0) == 0x80) i--; }
break;
case 'n' : s = va_arg(arg, char *);
if (F.hSize) * (short *) s = (short)nwritten;
else if (F.lSize) * (long *) s = (long)nwritten;
else * (int *) s = (int)nwritten;
continue;
default: s = mDNS_VACB;
i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "<<UNKNOWN FORMAT CONVERSION CODE %%%c>>", c);
case '%' : *sbuffer++ = (char)c;
if (++nwritten >= buflen) goto exit;
break;
}
if (i < F.fieldWidth && !F.leftJustify) // Pad on the left
do {
*sbuffer++ = ' ';
if (++nwritten >= buflen) goto exit;
} while (i < --F.fieldWidth);
// Make sure we don't truncate in the middle of a UTF-8 character.
// Note: s[i] is the first eliminated character; i.e. the next character *after* the last character of the
// allowed output. If s[i] is a UTF-8 continuation character, then we've cut a unicode character in half,
// so back up 'i' until s[i] is no longer a UTF-8 continuation character. (if the input was proprly
// formed, s[i] will now be the UTF-8 start character of the multi-byte character we just eliminated).
if (i > buflen - nwritten)
{ i = buflen - nwritten; while (i>0 && (s[i] & 0xC0) == 0x80) i--; }
for (j=0; j<i; j++) *sbuffer++ = *s++; // Write the converted result
nwritten += i;
if (nwritten >= buflen) goto exit;
for (; i < F.fieldWidth; i++) // Pad on the right
{
*sbuffer++ = ' ';
if (++nwritten >= buflen) goto exit;
}
}
}
exit:
*sbuffer++ = 0;
return(nwritten);
}
mDNSexport mDNSu32 mDNS_snprintf(char *sbuffer, mDNSu32 buflen, const char *fmt, ...)
{
mDNSu32 length;
va_list ptr;
va_start(ptr,fmt);
length = mDNS_vsnprintf(sbuffer, buflen, fmt, ptr);
va_end(ptr);
return(length);
}