nat46/src/464xlatcfg.c

   1 /* 464xlatcfg.c
   2  *
   3  * Copyright (c) 2015 Steven Barth <cyrus@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <netinet/icmp6.h>
  16 #include <netinet/in.h>
  17 #include <sys/socket.h>
  18 #include <arpa/inet.h>
  19 #include <net/if.h>
  20 #include <unistd.h>
  21 #include <stdlib.h>
  22 #include <signal.h>
  23 #include <stdio.h>
  24 #include <netdb.h>
  25
  26 int main(int argc, const char *argv[])
  27 {
  28         char buf[INET6_ADDRSTRLEN], prefix[INET6_ADDRSTRLEN + 4];
  29         int pid;
  30
  31         if (argc <= 1) {
  32                 fprintf(stderr, "Usage: %s <name> [ifname] [ipv6prefix] [ipv4addr] [ipv6addr]\n", argv[0]);
  33                 return 1;
  34         }
  35
  36         snprintf(buf, sizeof(buf), "/var/run/%s.pid", argv[1]);
  37         FILE *fp = fopen(buf, "r");
  38         if (fp) {
  39                 fscanf(fp, "%d", &pid);
  40                 kill(pid, SIGTERM);
  41                 unlink(buf);
  42                 fclose(fp);
  43         }
  44
  45         if (!argv[2])
  46                 return 0;
  47
  48         if (!argv[3] || !argv[4] || !(fp = fopen(buf, "wx")))
  49                 return 1;
  50
  51         prefix[sizeof(prefix) - 1] = 0;
  52         strncpy(prefix, argv[3], sizeof(prefix) - 1);
  53
  54         if (!prefix[0]) {
  55                 struct addrinfo hints = { .ai_family = AF_INET6 }, *res;
  56                 if (getaddrinfo("ipv4only.arpa", NULL, &hints, &res) || !res) {
  57                         sleep(3);
  58                         if (getaddrinfo("ipv4only.arpa", NULL, &hints, &res) || !res)
  59                                 return 2;
  60                 }
  61
  62                 struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)res->ai_addr;
  63                 inet_ntop(AF_INET6, &sin6->sin6_addr, prefix, sizeof(prefix) - 4);
  64                 strcat(prefix, "/96");
  65                 freeaddrinfo(res);
  66         }
  67
  68         struct sockaddr_in6 saddr = {.sin6_family = AF_INET6, .sin6_addr = {{{0x20, 0x01, 0x0d, 0xb8}}}};
  69         socklen_t saddrlen = sizeof(saddr);
  70         int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
  71         struct icmp6_filter filt;
  72         ICMP6_FILTER_SETBLOCKALL(&filt);
  73         setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
  74         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, argv[2], strlen(argv[2]));
  75         if (connect(sock, (struct sockaddr*)&saddr, sizeof(saddr)) ||
  76                         getsockname(sock, (struct sockaddr*)&saddr, &saddrlen))
  77                 return 3;
  78
  79         struct ipv6_mreq mreq = {saddr.sin6_addr, if_nametoindex(argv[2])};
  80         if (!argv[5]) {
  81                 srandom(mreq.ipv6mr_multiaddr.s6_addr32[0] ^ mreq.ipv6mr_multiaddr.s6_addr32[1] ^
  82                                 mreq.ipv6mr_multiaddr.s6_addr32[2] ^ mreq.ipv6mr_multiaddr.s6_addr32[3]);
  83                 mreq.ipv6mr_multiaddr.s6_addr32[2] = random();
  84                 mreq.ipv6mr_multiaddr.s6_addr32[3] = random();
  85         } else if (inet_pton(AF_INET6, argv[5], &mreq.ipv6mr_multiaddr) != 1) {
  86                 return 1;
  87         }
  88
  89         if (setsockopt(sock, SOL_IPV6, IPV6_JOIN_ANYCAST, &mreq, sizeof(mreq)))
  90                 return 3;
  91
  92         inet_ntop(AF_INET6, &mreq.ipv6mr_multiaddr, buf, sizeof(buf));
  93         fputs(buf, stdout);
  94         fputc('\n', stdout);
  95         fflush(stdout);
  96
  97         FILE *nat46 = fopen("/proc/net/nat46/control", "w");
  98         if (!nat46 || fprintf(nat46, "add %s\nconfig %s local.style NONE local.v4 %s/32 local.v6 %s/128 "
  99                         "remote.style RFC6052 remote.v6 %s\n", argv[1], argv[1], argv[4], buf, prefix) < 0 ||
 100                         fclose(nat46))
 101                 return 4;
 102
 103         if (!(pid = fork())) {
 104                 fclose(fp);
 105                 fclose(stdin);
 106                 fclose(stdout);
 107                 fclose(stderr);
 108                 chdir("/");
 109                 setsid();
 110                 pause();
 111         } else {
 112                 fprintf(fp, "%d\n", pid);
 113         }
 114
 115         return 0;
 116 }