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 static void sighandler(__attribute__((unused)) int signal)
  27 {
  28 }
  29
  30 int main(int argc, const char *argv[])
  31 {
  32         char buf[INET6_ADDRSTRLEN], prefix[INET6_ADDRSTRLEN + 4];
  33         int pid;
  34
  35         if (argc <= 1) {
  36                 fprintf(stderr, "Usage: %s <name> [ifname] [ipv6prefix] [ipv4addr] [ipv6addr]\n", argv[0]);
  37                 return 1;
  38         }
  39
  40         snprintf(buf, sizeof(buf), "/var/run/%s.pid", argv[1]);
  41         FILE *fp = fopen(buf, "r");
  42         if (fp) {
  43                 fscanf(fp, "%d", &pid);
  44                 kill(pid, SIGTERM);
  45                 unlink(buf);
  46                 fclose(fp);
  47         }
  48
  49         if (!argv[2])
  50                 return 0;
  51
  52         if (!argv[3] || !argv[4] || !(fp = fopen(buf, "wx")))
  53                 return 1;
  54
  55         signal(SIGTERM, sighandler);
  56
  57         prefix[sizeof(prefix) - 1] = 0;
  58         strncpy(prefix, argv[3], sizeof(prefix) - 1);
  59
  60         if (!prefix[0]) {
  61                 struct addrinfo hints = { .ai_family = AF_INET6 }, *res;
  62                 if (getaddrinfo("ipv4only.arpa", NULL, &hints, &res) || !res) {
  63                         sleep(3);
  64                         if (getaddrinfo("ipv4only.arpa", NULL, &hints, &res) || !res)
  65                                 return 2;
  66                 }
  67
  68                 struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)res->ai_addr;
  69                 inet_ntop(AF_INET6, &sin6->sin6_addr, prefix, sizeof(prefix) - 4);
  70                 strcat(prefix, "/96");
  71                 freeaddrinfo(res);
  72         }
  73
  74         int i = 0;
  75         int sock;
  76         struct sockaddr_in6 saddr;
  77
  78         do {
  79                 socklen_t saddrlen = sizeof(saddr);
  80                 struct icmp6_filter filt;
  81
  82                 sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
  83                 ICMP6_FILTER_SETBLOCKALL(&filt);
  84                 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
  85                 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, argv[2], strlen(argv[2]));
  86                 memset(&saddr, 0, sizeof(saddr));
  87                 saddr.sin6_family = AF_INET6;
  88                 saddr.sin6_addr.s6_addr32[0] = htonl(0x2001);
  89                 saddr.sin6_addr.s6_addr32[1] = htonl(0xdb8);
  90                 if (connect(sock, (struct sockaddr*)&saddr, sizeof(saddr)) ||
  91                                 getsockname(sock, (struct sockaddr*)&saddr, &saddrlen))
  92                         return 3;
  93
  94                 if (!IN6_IS_ADDR_LINKLOCAL(&saddr.sin6_addr) || argv[5])
  95                         break;
  96
  97                 close(sock);
  98                 sleep(3);
  99                 i++;
 100         } while (i < 3);
 101
 102         struct ipv6_mreq mreq = {saddr.sin6_addr, if_nametoindex(argv[2])};
 103         if (!argv[5]) {
 104                 if (IN6_IS_ADDR_LINKLOCAL(&mreq.ipv6mr_multiaddr))
 105                         return 5;
 106
 107                 srandom(mreq.ipv6mr_multiaddr.s6_addr32[0] ^ mreq.ipv6mr_multiaddr.s6_addr32[1] ^
 108                                 mreq.ipv6mr_multiaddr.s6_addr32[2] ^ mreq.ipv6mr_multiaddr.s6_addr32[3]);
 109                 mreq.ipv6mr_multiaddr.s6_addr32[2] = random();
 110                 mreq.ipv6mr_multiaddr.s6_addr32[3] = random();
 111         } else if (inet_pton(AF_INET6, argv[5], &mreq.ipv6mr_multiaddr) != 1) {
 112                 return 1;
 113         }
 114
 115         if (setsockopt(sock, SOL_IPV6, IPV6_JOIN_ANYCAST, &mreq, sizeof(mreq)))
 116                 return 3;
 117
 118         inet_ntop(AF_INET6, &mreq.ipv6mr_multiaddr, buf, sizeof(buf));
 119         fputs(buf, stdout);
 120         fputc('\n', stdout);
 121         fflush(stdout);
 122
 123         FILE *nat46 = fopen("/proc/net/nat46/control", "w");
 124         if (!nat46 || fprintf(nat46, "add %s\nconfig %s local.style NONE local.v4 %s/32 local.v6 %s/128 "
 125                         "remote.style RFC6052 remote.v6 %s\n", argv[1], argv[1], argv[4], buf, prefix) < 0 ||
 126                         fclose(nat46))
 127                 return 4;
 128
 129         if (!(pid = fork())) {
 130                 fclose(fp);
 131                 fclose(stdin);
 132                 fclose(stdout);
 133                 fclose(stderr);
 134                 chdir("/");
 135                 setsid();
 136                 pause();
 137
 138                 nat46 = fopen("/proc/net/nat46/control", "w");
 139                 if (nat46) {
 140                         fprintf(nat46, "del %s\n", argv[1]);
 141                         fclose(nat46);
 142                 }
 143         } else {
 144                 fprintf(fp, "%d\n", pid);
 145         }
 146
 147         return 0;
 148 }