Google Git Google Git
Sign in
android/platform/packages/modules/DnsResolver/refs/heads/android17-security-release/./gethnamaddr.cpp
blob: 9a4e0ed48582b988223c91dace77c3e64a532a16 [file] [edit]
/* $NetBSD: gethnamaddr.c,v 1.91 2014/06/19 15:08:18 christos Exp $ */
/*
* ++Copyright++ 1985, 1988, 1993
* -
* Copyright (c) 1985, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* -
* Portions Copyright (c) 1993 by Digital Equipment Corporation.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies, and that
* the name of Digital Equipment Corporation not be used in advertising or
* publicity pertaining to distribution of the document or software without
* specific, written prior permission.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
* -
* --Copyright--
*/
#define LOG_TAG "resolv"
#include "gethnamaddr.h"
#include <android-base/logging.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <functional>
#include <vector>
#include "Experiments.h"
#include "hostent.h"
#include "netd_resolv/resolv.h"
#include "res_comp.h"
#include "res_debug.h" // p_class(), p_type()
#include "resolv_cache.h"
#include "resolv_private.h"
#include "stats.pb.h"
using android::net::NetworkDnsEventReported;
constexpr int MAXADDRS = 35;
typedef union {
HEADER hdr;
uint8_t buf[MAXPACKET];
} querybuf;
static void pad_v4v6_hostent(struct hostent* hp, char** bpp, char* ep);
static int dns_gethtbyaddr(const unsigned char* uaddr, int len, int af,
const android_net_context* netcontext, std::optional<int> app_socket,
getnamaddr* info, NetworkDnsEventReported* event);
static int dns_gethtbyname(ResState* res, const char* name, int af, getnamaddr* info);
#define BOUNDED_INCR(x) \
do { \
BOUNDS_CHECK(cp, x); \
cp += (x); \
} while (0)
#define BOUNDS_CHECK(ptr, count) \
do { \
if (eom - (ptr) < (count)) goto no_recovery; \
} while (0)
static struct hostent* getanswer(const querybuf* _Nonnull answer, int anslen, const char* qname,
int qtype, struct hostent* hent, char* buf, size_t buflen,
int* he) {
const HEADER* hp;
const uint8_t* cp;
int n;
size_t qlen;
const uint8_t *eom, *erdata;
char *bp, **hap, *ep;
int ancount, qdcount;
int haveanswer, had_error;
int toobig = 0;
char tbuf[MAXDNAME];
char* addr_ptrs[MAXADDRS];
const char* tname;
std::vector<char*> aliases;
tname = qname;
hent->h_name = NULL;
eom = answer->buf + anslen;
bool (*name_ok)(const char* dn);
switch (qtype) {
case T_A:
case T_AAAA:
name_ok = res_hnok;
break;
case T_PTR:
name_ok = res_dnok;
break;
default:
*he = NO_RECOVERY;
return NULL; /* XXX should be abort(); */
}
/*
* find first satisfactory answer
*/
hp = &answer->hdr;
ancount = ntohs(hp->ancount);
qdcount = ntohs(hp->qdcount);
bp = buf;
ep = buf + buflen;
cp = answer->buf;
BOUNDED_INCR(HFIXEDSZ);
if (qdcount != 1) goto no_recovery;
n = dn_expand(answer->buf, eom, cp, bp, (int) (ep - bp));
if ((n < 0) || !name_ok(bp)) goto no_recovery;
BOUNDED_INCR(n + QFIXEDSZ);
if (qtype == T_A || qtype == T_AAAA) {
/* res_send() has already verified that the query name is the
* same as the one we sent; this just gets the expanded name
* (i.e., with the succeeding search-domain tacked on).
*/
n = (int) strlen(bp) + 1; /* for the \0 */
if (n >= MAXHOSTNAMELEN) goto no_recovery;
hent->h_name = bp;
bp += n;
/* The qname can be abbreviated, but h_name is now absolute. */
qname = hent->h_name;
}
hent->h_addr_list = hap = addr_ptrs;
*hap = NULL;
haveanswer = 0;
had_error = 0;
while (ancount-- > 0 && cp < eom && !had_error) {
n = dn_expand(answer->buf, eom, cp, bp, (int) (ep - bp));
if ((n < 0) || !name_ok(bp)) {
had_error++;
continue;
}
cp += n; /* name */
BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
int type = ntohs(*reinterpret_cast<const uint16_t*>(cp));
cp += INT16SZ; /* type */
int cl = ntohs(*reinterpret_cast<const uint16_t*>(cp));
cp += INT16SZ + INT32SZ; /* class, TTL */
n = ntohs(*reinterpret_cast<const uint16_t*>(cp));
cp += INT16SZ; /* len */
BOUNDS_CHECK(cp, n);
erdata = cp + n;
if (cl != C_IN) {
/* XXX - debug? syslog? */
cp += n;
continue; /* XXX - had_error++ ? */
}
if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
n = dn_expand(answer->buf, eom, cp, tbuf, (int) sizeof tbuf);
if ((n < 0) || !name_ok(tbuf)) {
had_error++;
continue;
}
cp += n;
if (cp != erdata) goto no_recovery;
/* Store alias. */
aliases.push_back(bp);
n = (int) strlen(bp) + 1; /* for the \0 */
if (n >= MAXHOSTNAMELEN) {
had_error++;
continue;
}
bp += n;
/* Get canonical name. */
n = (int) strlen(tbuf) + 1; /* for the \0 */
if (n > ep - bp || n >= MAXHOSTNAMELEN) {
had_error++;
continue;
}
strlcpy(bp, tbuf, (size_t)(ep - bp));
hent->h_name = bp;
bp += n;
continue;
}
if (qtype == T_PTR && type == T_CNAME) {
n = dn_expand(answer->buf, eom, cp, tbuf, (int) sizeof tbuf);
if (n < 0 || !res_dnok(tbuf)) {
had_error++;
continue;
}
cp += n;
if (cp != erdata) goto no_recovery;
/* Get canonical name. */
n = (int) strlen(tbuf) + 1; /* for the \0 */
if (n > ep - bp || n >= MAXHOSTNAMELEN) {
had_error++;
continue;
}
strlcpy(bp, tbuf, (size_t)(ep - bp));
tname = bp;
bp += n;
continue;
}
if (type != qtype) {
if (type != T_KEY && type != T_SIG)
LOG(DEBUG) << __func__ << ": asked for \"" << qname << " " << p_class(C_IN) << " "
<< p_type(qtype) << "\", got type \"" << p_type(type) << "\"";
cp += n;
continue; /* XXX - had_error++ ? */
}
switch (type) {
case T_PTR:
if (strcasecmp(tname, bp) != 0) {
LOG(DEBUG) << __func__ << ": asked for \"" << qname << "\", got \"" << bp
<< "\"";
cp += n;
continue; /* XXX - had_error++ ? */
}
n = dn_expand(answer->buf, eom, cp, bp, (int) (ep - bp));
if ((n < 0) || !res_hnok(bp)) {
had_error++;
break;
}
cp += n;
if (cp != erdata) goto no_recovery;
if (!haveanswer)
hent->h_name = bp;
else
aliases.push_back(bp);
if (n != -1) {
n = (int) strlen(bp) + 1; /* for the \0 */
if (n >= MAXHOSTNAMELEN) {
had_error++;
break;
}
bp += n;
}
break;
case T_A:
case T_AAAA: {
if (hent->h_name == NULL) goto no_recovery;
const char* h_name = hent->h_name;
if (strcasecmp(h_name, bp) != 0) {
LOG(DEBUG) << __func__ << ": asked for \"" << h_name << "\", got \"" << bp
<< "\"";
cp += n;
continue; /* XXX - had_error++ ? */
}
if (n != hent->h_length) {
cp += n;
continue;
}
if (type == T_AAAA) {
struct in6_addr in6;
memcpy(&in6, cp, NS_IN6ADDRSZ);
if (IN6_IS_ADDR_V4MAPPED(&in6)) {
cp += n;
continue;
}
}
if (!haveanswer) {
int nn;
hent->h_name = bp;
nn = (int) strlen(bp) + 1; /* for the \0 */
bp += nn;
}
bp = align_ptr<sizeof(int32_t)>(bp);
if (bp + n >= ep) {
LOG(DEBUG) << __func__ << ": size (" << n << ") too big";
had_error++;
continue;
}
if (hap >= &addr_ptrs[MAXADDRS - 1]) {
if (!toobig++) {
LOG(DEBUG) << __func__ << ": Too many addresses (" << MAXADDRS << ")";
}
cp += n;
continue;
}
(void) memcpy(*hap++ = bp, cp, (size_t) n);
bp += n;
cp += n;
if (cp != erdata) goto no_recovery;
break;
}
default:
abort();
}
if (!had_error) haveanswer++;
}
if (haveanswer) {
*hap = NULL;
if (!hent->h_name) {
n = (int) strlen(qname) + 1; /* for the \0 */
if (n > ep - bp || n >= MAXHOSTNAMELEN) goto no_recovery;
strlcpy(bp, qname, (size_t)(ep - bp));
hent->h_name = bp;
bp += n;
}
if (hent->h_addrtype == AF_INET) pad_v4v6_hostent(hent, &bp, ep);
goto success;
}
no_recovery:
*he = NO_RECOVERY;
return NULL;
success:
bp = align_ptr(bp);
aliases.push_back(nullptr);
qlen = aliases.size() * sizeof(*hent->h_aliases);
if ((size_t)(ep - bp) < qlen) goto nospc;
hent->h_aliases = (char**) bp;
memcpy(bp, aliases.data(), qlen);
bp += qlen;
n = (int) (hap - addr_ptrs);
qlen = (n + 1) * sizeof(*hent->h_addr_list);
if ((size_t)(ep - bp) < qlen) goto nospc;
hent->h_addr_list = (char**) bp;
memcpy(bp, addr_ptrs, qlen);
*he = NETDB_SUCCESS;
return hent;
nospc:
errno = ENOSPC;
*he = NETDB_INTERNAL;
return NULL;
}
int resolv_gethostbyname(const char* name, int af, hostent* hp, char* buf, size_t buflen,
const android_net_context* netcontext, std::optional<int> app_socket,
hostent** result, NetworkDnsEventReported* event) {
if (name == nullptr || hp == nullptr) {
return EAI_SYSTEM;
}
getnamaddr info;
ResState res(netcontext, app_socket, event);
setMdnsFlag(name, res.netid, &(res.flags));
size_t size;
switch (af) {
case AF_INET:
size = NS_INADDRSZ;
break;
case AF_INET6:
size = NS_IN6ADDRSZ;
break;
default:
return EAI_FAMILY;
}
if (buflen < size) goto nospc;
hp->h_addrtype = af;
hp->h_length = (int) size;
/*
* disallow names consisting only of digits/dots, unless
* they end in a dot.
*/
if (isdigit((uint8_t)name[0])) {
for (const char* cp = name;; ++cp) {
if (!*cp) {
if (*--cp == '.') break;
/*
* All-numeric, no dot at the end.
* Fake up a hostent as if we'd actually
* done a lookup.
*/
goto fake;
}
if (!isdigit((uint8_t)*cp) && *cp != '.') break;
}
}
if ((isxdigit((uint8_t)name[0]) && strchr(name, ':') != NULL) || name[0] == ':') {
for (const char* cp = name;; ++cp) {
if (!*cp) {
if (*--cp == '.') break;
/*
* All-IPv6-legal, no dot at the end.
* Fake up a hostent as if we'd actually
* done a lookup.
*/
goto fake;
}
if (!isxdigit((uint8_t)*cp) && *cp != ':' && *cp != '.') break;
}
}
info.hp = hp;
info.buf = buf;
info.buflen = buflen;
if (_hf_gethtbyname2(name, af, &info)) {
int error = dns_gethtbyname(&res, name, af, &info);
if (error != 0) return error;
}
*result = hp;
return 0;
nospc:
return EAI_MEMORY;
fake:
HENT_ARRAY(hp->h_addr_list, 1, buf, buflen);
HENT_ARRAY(hp->h_aliases, 0, buf, buflen);
hp->h_aliases[0] = NULL;
if (size > buflen) goto nospc;
if (inet_pton(af, name, buf) <= 0) {
return EAI_NODATA;
}
hp->h_addr_list[0] = buf;
hp->h_addr_list[1] = NULL;
buf += size;
buflen -= size;
HENT_SCOPY(hp->h_name, name, buf, buflen);
*result = hp;
return 0;
}
int resolv_gethostbyaddr(const void* _Nonnull addr, socklen_t len, int af, hostent* hp, char* buf,
size_t buflen, const struct android_net_context* netcontext,
std::optional<int> app_socket, hostent** result,
NetworkDnsEventReported* event) {
const uint8_t* uaddr = (const uint8_t*)addr;
socklen_t size;
struct getnamaddr info;
if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
(IN6_IS_ADDR_LINKLOCAL((const struct in6_addr*) addr) ||
IN6_IS_ADDR_SITELOCAL((const struct in6_addr*) addr))) {
return EAI_NODATA;
}
if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
(IN6_IS_ADDR_V4MAPPED((const struct in6_addr*) addr) ||
IN6_IS_ADDR_V4COMPAT((const struct in6_addr*) addr))) {
/* Unmap. */
uaddr += NS_IN6ADDRSZ - NS_INADDRSZ;
addr = uaddr;
af = AF_INET;
len = NS_INADDRSZ;
}
switch (af) {
case AF_INET:
size = NS_INADDRSZ;
break;
case AF_INET6:
size = NS_IN6ADDRSZ;
break;
default:
return EAI_FAMILY;
}
if (size != len) {
// TODO: Consider converting to a private extended EAI_* error code.
// Currently, the EAI_* value has no corresponding error code for invalid argument socket
// length. In order to not rely on errno, convert the original error code pair, EAI_SYSTEM
// and EINVAL, to EAI_FAIL.
return EAI_FAIL;
}
info.hp = hp;
info.buf = buf;
info.buflen = buflen;
if (_hf_gethtbyaddr(uaddr, len, af, &info)) {
int error = dns_gethtbyaddr(uaddr, len, af, netcontext, app_socket, &info, event);
if (error != 0) return error;
}
*result = hp;
return 0;
}
// TODO: Consider leaving function without returning error code as _gethtent() does because
// the error code of the caller does not currently return to netd.
struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, size_t buflen,
int* he) {
char *name;
char* cp;
int af, len;
size_t anum;
struct in6_addr host_addr;
std::vector<char*> aliases;
if (hf == NULL) {
*he = NETDB_INTERNAL;
errno = EINVAL;
return NULL;
}
char* p = NULL;
// Allocate a new space to read file lines like upstream does.
const size_t line_buf_size = MAXPACKET;
if ((p = (char*) malloc(line_buf_size)) == NULL) {
goto nospc;
}
for (;;) {
if (!fgets(p, line_buf_size, hf)) {
free(p);
*he = HOST_NOT_FOUND;
return NULL;
}
if (*p == '#') {
continue;
}
if (!(cp = strpbrk(p, "#\n"))) {
continue;
}
*cp = '\0';
if (!(cp = strpbrk(p, " \t"))) continue;
*cp++ = '\0';
if (inet_pton(AF_INET6, p, &host_addr) > 0) {
af = AF_INET6;
len = NS_IN6ADDRSZ;
} else {
if (inet_pton(AF_INET, p, &host_addr) <= 0) continue;
af = AF_INET;
len = NS_INADDRSZ;
}
/* if this is not something we're looking for, skip it. */
if (hent->h_addrtype != 0 && hent->h_addrtype != af) continue;
if (hent->h_length != 0 && hent->h_length != len) continue;
while (*cp == ' ' || *cp == '\t') cp++;
if ((cp = strpbrk(name = cp, " \t")) != NULL) *cp++ = '\0';
while (cp && *cp) {
if (*cp == ' ' || *cp == '\t') {
cp++;
continue;
}
aliases.push_back(cp);
if ((cp = strpbrk(cp, " \t")) != NULL) *cp++ = '\0';
}
break;
}
hent->h_length = len;
hent->h_addrtype = af;
HENT_ARRAY(hent->h_addr_list, 1, buf, buflen);
anum = aliases.size();
HENT_ARRAY(hent->h_aliases, anum, buf, buflen);
HENT_COPY(hent->h_addr_list[0], &host_addr, hent->h_length, buf, buflen);
hent->h_addr_list[1] = NULL;
/* Reserve space for mapping IPv4 address to IPv6 address in place */
if (hent->h_addrtype == AF_INET) {
HENT_COPY(buf, NAT64_PAD, sizeof(NAT64_PAD), buf, buflen);
}
HENT_SCOPY(hent->h_name, name, buf, buflen);
for (size_t i = 0; i < anum; i++) HENT_SCOPY(hent->h_aliases[i], aliases[i], buf, buflen);
hent->h_aliases[anum] = NULL;
*he = NETDB_SUCCESS;
free(p);
return hent;
nospc:
free(p);
errno = ENOSPC;
*he = NETDB_INTERNAL;
return NULL;
}
/* Reserve space for mapping IPv4 address to IPv6 address in place */
static void pad_v4v6_hostent(struct hostent* _Nonnull hp, char** _Nonnull bpp, char* _Nonnull ep) {
if (hp->h_addrtype != AF_INET || hp->h_length != NS_INADDRSZ) return;
for (char** ap = hp->h_addr_list; *ap; ap++) {
char* const bp = align_ptr<sizeof(int32_t)>(*bpp);
if (ep - bp < NS_IN6ADDRSZ) {
// Out of space. Truncate address list here.
*ap = nullptr;
return;
}
memcpy(bp, *ap, NS_INADDRSZ);
memcpy(bp + NS_INADDRSZ, NAT64_PAD, sizeof(NAT64_PAD));
*ap = bp;
*bpp = bp + NS_IN6ADDRSZ;
}
}
static int dns_gethtbyname(ResState* res, const char* name, int addr_type, getnamaddr* info) {
int n, type;
info->hp->h_addrtype = addr_type;
switch (info->hp->h_addrtype) {
case AF_INET:
info->hp->h_length = NS_INADDRSZ;
type = T_A;
break;
case AF_INET6:
info->hp->h_length = NS_IN6ADDRSZ;
type = T_AAAA;
break;
default:
return EAI_FAMILY;
}
auto buf = std::make_unique<querybuf>();
int he;
n = res_nsearch(res, name, C_IN, type, {buf->buf, (int)sizeof(buf->buf)}, &he);
if (n < 0) {
LOG(DEBUG) << __func__ << ": res_nsearch failed (" << n << ")";
// Return h_errno (he) to catch more detailed errors rather than EAI_NODATA.
// Note that res_nsearch() doesn't set the pair NETDB_INTERNAL and errno.
// See also herrnoToAiErrno().
return herrnoToAiErrno(he);
}
hostent* hp = getanswer(buf.get(), n, name, type, info->hp, info->buf, info->buflen, &he);
if (hp == NULL) return herrnoToAiErrno(he);
return 0;
}
static int dns_gethtbyaddr(const unsigned char* uaddr, int len, int af,
const android_net_context* netcontext, std::optional<int> app_socket,
getnamaddr* info, NetworkDnsEventReported* event) {
char qbuf[MAXDNAME + 1], *qp, *ep;
int n;
int advance;
info->hp->h_length = len;
info->hp->h_addrtype = af;
switch (info->hp->h_addrtype) {
case AF_INET:
(void) snprintf(qbuf, sizeof(qbuf), "%u.%u.%u.%u.in-addr.arpa", (uaddr[3] & 0xff),
(uaddr[2] & 0xff), (uaddr[1] & 0xff), (uaddr[0] & 0xff));
break;
case AF_INET6:
qp = qbuf;
ep = qbuf + sizeof(qbuf) - 1;
for (n = NS_IN6ADDRSZ - 1; n >= 0; n--) {
advance = snprintf(qp, (size_t)(ep - qp), "%x.%x.", uaddr[n] & 0xf,
((unsigned int) uaddr[n] >> 4) & 0xf);
if (advance > 0 && qp + advance < ep)
qp += advance;
else {
// TODO: Consider converting to a private extended EAI_* error code.
// Currently, the EAI_* value has no corresponding error code for an internal
// out of buffer space. In order to not rely on errno, convert the original
// error code EAI_SYSTEM to EAI_MEMORY.
return EAI_MEMORY;
}
}
if (strlcat(qbuf, "ip6.arpa", sizeof(qbuf)) >= sizeof(qbuf)) {
// TODO: Consider converting to a private extended EAI_* error code.
// Currently, the EAI_* value has no corresponding error code for an internal
// out of buffer space. In order to not rely on errno, convert the original
// error code EAI_SYSTEM to EAI_MEMORY.
return EAI_MEMORY;
}
break;
default:
return EAI_FAMILY;
}
auto buf = std::make_unique<querybuf>();
ResState res(netcontext, app_socket, event);
int he;
n = res_nquery(&res, qbuf, C_IN, T_PTR, {buf->buf, (int)sizeof(buf->buf)}, &he);
if (n < 0) {
LOG(DEBUG) << __func__ << ": res_nquery failed (" << n << ")";
// Note that res_nquery() doesn't set the pair NETDB_INTERNAL and errno.
// Return h_errno (he) to catch more detailed errors rather than EAI_NODATA.
// See also herrnoToAiErrno().
return herrnoToAiErrno(he);
}
hostent* hp = getanswer(buf.get(), n, qbuf, T_PTR, info->hp, info->buf, info->buflen, &he);
if (hp == NULL) return herrnoToAiErrno(he);
char* bf = (char*) (hp->h_addr_list + 2);
size_t blen = (size_t)(bf - info->buf);
if (blen + info->hp->h_length > info->buflen) goto nospc;
hp->h_addr_list[0] = bf;
hp->h_addr_list[1] = NULL;
memcpy(bf, uaddr, (size_t) info->hp->h_length);
/* Reserve enough space for mapping IPv4 address to IPv6 address in place */
if (info->hp->h_addrtype == AF_INET) {
if (blen + NS_IN6ADDRSZ > info->buflen) goto nospc;
// Pad zero to the unused address space
memcpy(bf + NS_INADDRSZ, NAT64_PAD, sizeof(NAT64_PAD));
}
return 0;
nospc:
return EAI_MEMORY;
}
int herrnoToAiErrno(int he) {
switch (he) {
// extended h_errno
case NETD_RESOLV_H_ERRNO_EXT_TIMEOUT:
return NETD_RESOLV_TIMEOUT;
// legacy h_errno
case NETDB_SUCCESS:
return 0;
case HOST_NOT_FOUND: // TODO: Perhaps convert HOST_NOT_FOUND to EAI_NONAME instead
case NO_DATA: // NO_ADDRESS
return EAI_NODATA;
case TRY_AGAIN:
return EAI_AGAIN;
case NETDB_INTERNAL:
// TODO: Remove ENOSPC and call abort() immediately whenever any allocation fails.
if (errno == ENOSPC) return EAI_MEMORY;
// Theoretically, this should not happen. Leave this here just in case.
// Currently, getanswer() of {gethnamaddr, getaddrinfo}.cpp, res_nsearch() and
// res_searchN() use this function to convert error code. Only getanswer()
// of gethnamaddr.cpp may return the error code pair, herrno NETDB_INTERNAL and
// errno ENOSPC, which has already converted to EAI_MEMORY. The remaining functions
// don't set the pair herrno and errno.
return EAI_SYSTEM; // see errno for detail
case NO_RECOVERY:
default:
return EAI_FAIL; // TODO: Perhaps convert default to EAI_MAX (unknown error) instead
}
}
void setMdnsFlag(std::string_view hostname, unsigned netid, uint32_t* flags) {
if (hostname.ends_with(".local") && is_mdns_supported_network(netid) &&
android::net::Experiments::getInstance()->getFlag("mdns_resolution", 1))
*flags |= RES_F_MDNS;
}
bool isMdnsResolution(uint32_t flags) {
return flags & RES_F_MDNS;
}