73 lines
2.4 KiB
C
73 lines
2.4 KiB
C
/*
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* Copyright 2011 Daniel Drown
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* dns64.c - find the nat64 prefix with a dns64 lookup
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*/
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <netdb.h>
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#include <strings.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "dns64.h"
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#include "logging.h"
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#include "resolv_netid.h"
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/* function: plat_prefix
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* looks up an ipv4-only hostname and looks for a nat64 /96 prefix, returns 1 on success, 0 on failure
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* ipv4_name - name to lookup
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* net_id - (optional) netId to use, NETID_UNSET indicates use of default network
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* prefix - the plat /96 prefix
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*/
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int plat_prefix(const char *ipv4_name, unsigned net_id, struct in6_addr *prefix) {
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const struct addrinfo hints = {
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.ai_family = AF_INET6,
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};
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int status;
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struct addrinfo *result = NULL;
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struct in6_addr plat_addr;
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char plat_addr_str[INET6_ADDRSTRLEN];
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logmsg(ANDROID_LOG_INFO, "Detecting NAT64 prefix from DNS...");
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status = android_getaddrinfofornet(ipv4_name, NULL, &hints, net_id, MARK_UNSET, &result);
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if (status != 0 || result == NULL) {
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logmsg(ANDROID_LOG_ERROR, "plat_prefix/dns(%s) status = %d/%s",
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ipv4_name, status, gai_strerror(status));
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return 0;
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}
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// Use only the first result. If other records are present, possibly with
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// differing DNS64 prefixes they are ignored (there is very little sensible
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// that could be done with them at this time anyway).
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if (result->ai_family != AF_INET6) {
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logmsg(ANDROID_LOG_WARN, "plat_prefix/unexpected address family: %d", result->ai_family);
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return 0;
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}
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plat_addr = ((struct sockaddr_in6 *)result->ai_addr)->sin6_addr;
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// Only /96 DNS64 prefixes are supported at this time.
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plat_addr.s6_addr32[3] = 0;
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freeaddrinfo(result);
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logmsg(ANDROID_LOG_INFO, "Detected NAT64 prefix %s/96",
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inet_ntop(AF_INET6, &plat_addr, plat_addr_str, sizeof(plat_addr_str)));
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*prefix = plat_addr;
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return 1;
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}
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