nat46/src/464xlatcfg.c

   1 /* 464xlatcfg.c
   2  *
   3  * Copyright (c) 2015 Steven Barth <cyrus@openwrt.org>
   4  * Copyright (c) 2017 Hans Dedecker <dedeckeh@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2
   8  * as published by the Free Software Foundation
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <netinet/icmp6.h>
  17 #include <netinet/in.h>
  18 #include <sys/socket.h>
  19 #include <arpa/inet.h>
  20 #include <net/if.h>
  21 #include <unistd.h>
  22 #include <stdlib.h>
  23 #include <signal.h>
  24 #include <stdio.h>
  25 #include <netdb.h>
  26
  27 static void sighandler(__attribute__((unused)) int signal)
  28 {
  29 }
  30
  31 int main(int argc, const char *argv[])
  32 {
  33         char buf[INET6_ADDRSTRLEN], prefix[INET6_ADDRSTRLEN + 4];
  34         int pid;
  35
  36         if (argc <= 1) {
  37                 fprintf(stderr, "Usage: %s <name> [ifname] [ipv6prefix] [ipv4addr] [ipv6addr]\n", argv[0]);
  38                 return 1;
  39         }
  40
  41         snprintf(buf, sizeof(buf), "/var/run/%s.pid", argv[1]);
  42         FILE *fp = fopen(buf, "r");
  43         if (fp) {
  44                 if (fscanf(fp, "%d", &pid) == 1)
  45                         kill(pid, SIGTERM);
  46
  47                 unlink(buf);
  48                 fclose(fp);
  49         }
  50
  51         if (!argv[2])
  52                 return 0;
  53
  54         if (!argv[3] || !argv[4] || !(fp = fopen(buf, "wx")))
  55                 return 1;
  56
  57         signal(SIGTERM, SIG_DFL);
  58         setvbuf(fp, NULL, _IOLBF, 0);
  59         fprintf(fp, "%d\n", getpid());
  60
  61         prefix[sizeof(prefix) - 1] = 0;
  62         strncpy(prefix, argv[3], sizeof(prefix) - 1);
  63
  64         if (!prefix[0]) {
  65                 struct addrinfo hints = { .ai_family = AF_INET6 }, *res;
  66                 if (getaddrinfo("ipv4only.arpa", NULL, &hints, &res) || !res) {
  67                         sleep(3);
  68                         if (getaddrinfo("ipv4only.arpa", NULL, &hints, &res) || !res)
  69                                 return 2;
  70                 }
  71
  72                 struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)res->ai_addr;
  73                 inet_ntop(AF_INET6, &sin6->sin6_addr, prefix, sizeof(prefix) - 4);
  74                 strcat(prefix, "/96");
  75                 freeaddrinfo(res);
  76         }
  77
  78         int i = 0;
  79         int sock;
  80         struct sockaddr_in6 saddr;
  81
  82         do {
  83                 socklen_t saddrlen = sizeof(saddr);
  84                 struct icmp6_filter filt;
  85
  86                 sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
  87                 ICMP6_FILTER_SETBLOCKALL(&filt);
  88                 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
  89                 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, argv[2], strlen(argv[2]));
  90                 memset(&saddr, 0, sizeof(saddr));
  91                 saddr.sin6_family = AF_INET6;
  92                 saddr.sin6_addr.s6_addr32[0] = htonl(0x2001);
  93                 saddr.sin6_addr.s6_addr32[1] = htonl(0xdb8);
  94                 if (connect(sock, (struct sockaddr*)&saddr, sizeof(saddr)) ||
  95                                 getsockname(sock, (struct sockaddr*)&saddr, &saddrlen))
  96                         return 3;
  97
  98                 if (!IN6_IS_ADDR_LINKLOCAL(&saddr.sin6_addr) || argv[5])
  99                         break;
 100
 101                 close(sock);
 102                 sleep(3);
 103                 i++;
 104         } while (i < 3);
 105
 106         struct ipv6_mreq mreq = {saddr.sin6_addr, if_nametoindex(argv[2])};
 107         if (!argv[5]) {
 108                 if (IN6_IS_ADDR_LINKLOCAL(&mreq.ipv6mr_multiaddr))
 109                         return 5;
 110
 111                 srandom(mreq.ipv6mr_multiaddr.s6_addr32[0] ^ mreq.ipv6mr_multiaddr.s6_addr32[1] ^
 112                                 mreq.ipv6mr_multiaddr.s6_addr32[2] ^ mreq.ipv6mr_multiaddr.s6_addr32[3]);
 113                 mreq.ipv6mr_multiaddr.s6_addr32[2] = random();
 114                 mreq.ipv6mr_multiaddr.s6_addr32[3] = random();
 115         } else if (inet_pton(AF_INET6, argv[5], &mreq.ipv6mr_multiaddr) != 1) {
 116                 return 1;
 117         }
 118
 119         if (setsockopt(sock, SOL_IPV6, IPV6_JOIN_ANYCAST, &mreq, sizeof(mreq)))
 120                 return 3;
 121
 122         inet_ntop(AF_INET6, &mreq.ipv6mr_multiaddr, buf, sizeof(buf));
 123         fputs(buf, stdout);
 124         fputc('\n', stdout);
 125         fflush(stdout);
 126
 127         FILE *nat46 = fopen("/proc/net/nat46/control", "w");
 128         if (!nat46 || fprintf(nat46, "add %s\nconfig %s local.style NONE local.v4 %s/32 local.v6 %s/128 "
 129                         "remote.style RFC6052 remote.v6 %s\n", argv[1], argv[1], argv[4], buf, prefix) < 0 ||
 130                         fclose(nat46))
 131                 return 4;
 132
 133         if (!(pid = fork())) {
 134                 fclose(fp);
 135                 fclose(stdin);
 136                 fclose(stdout);
 137                 fclose(stderr);
 138                 chdir("/");
 139                 setsid();
 140                 signal(SIGTERM, sighandler);
 141                 pause();
 142
 143                 nat46 = fopen("/proc/net/nat46/control", "w");
 144                 if (nat46) {
 145                         fprintf(nat46, "del %s\n", argv[1]);
 146                         fclose(nat46);
 147                 }
 148         } else {
 149                 rewind(fp);
 150                 fprintf(fp, "%d\n", pid);
 151         }
 152
 153         return 0;
 154 }