blob: ab662c714fff13381535b0b2f3cd16398ca179f5 [file] [log] [blame]
/*
* Copyright 2011 Daniel Drown
*
* 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.
*
* dns64.c - find the nat64 prefix with a dns64 lookup
*/
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <strings.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "dns64.h"
#include "logging.h"
/* function: plat_prefix
* looks up an ipv4-only hostname and looks for a nat64 /96 prefix, returns 1 on success, 0 on temporary failure, -1 on permanent failure
* ipv4_name - name to lookup
* prefix - the plat /96 prefix
*/
int plat_prefix(const char *ipv4_name, struct in6_addr *prefix) {
struct addrinfo hints, *result, *p;
int status, plat_addr_set, ipv4_records, ipv6_records;
struct in6_addr plat_addr, this_plat_addr;
struct sockaddr_in6 *this_addr;
result = NULL;
plat_addr_set = 0;
ipv4_records = ipv6_records = 0;
bzero(&hints, sizeof(hints));
hints.ai_family = AF_UNSPEC;
status = getaddrinfo(ipv4_name, NULL, &hints, &result);
if(status != 0) {
logmsg(ANDROID_LOG_ERROR,"plat_prefix/dns(%s) status = %d/%s\n", ipv4_name, status, gai_strerror(status));
return 0;
}
for(p = result; p; p = p->ai_next) {
if(p->ai_family == AF_INET) {
ipv4_records++;
continue;
}
if(p->ai_family != AF_INET6) {
logmsg(ANDROID_LOG_WARN,"plat_prefix/unexpected address family: %d\n", p->ai_family);
continue;
}
ipv6_records++;
this_addr = (struct sockaddr_in6 *)p->ai_addr;
this_plat_addr = this_addr->sin6_addr;
this_plat_addr.s6_addr32[3] = 0;
if(!plat_addr_set) {
plat_addr = this_plat_addr;
plat_addr_set = 1;
continue;
}
if(!IN6_ARE_ADDR_EQUAL(&plat_addr, &this_plat_addr)) {
char plat_addr_str[INET6_ADDRSTRLEN], this_plat_addr_str[INET6_ADDRSTRLEN];
logmsg(ANDROID_LOG_ERROR,"plat_prefix/two different plat addrs = %s,%s",
inet_ntop(AF_INET6, &plat_addr, plat_addr_str, sizeof(plat_addr_str)),
inet_ntop(AF_INET6, &this_plat_addr, this_plat_addr_str, sizeof(this_plat_addr_str))
);
}
}
if(result != NULL) {
freeaddrinfo(result);
}
if(ipv4_records > 0 && ipv6_records == 0) {
logmsg(ANDROID_LOG_WARN,"plat_prefix/no dns64 detected\n");
return -1;
}
*prefix = plat_addr;
return 1;
}