src/vpn/tcp.c

   1 #include "debug.h"
   2 #include "packet.h"
   3 #include "tcp.h"
   4
   5 #include <errno.h>
   6 #include <netinet/in.h>
   7 #include <netinet/ip.h>
   8 #include <signal.h>
   9 #include <stdlib.h>
  10 #include <arpa/inet.h>
  11 #include <string.h>
  12 #include <sys/socket.h>
  13 #include <sys/types.h>
  14 #include <unistd.h>
  15
  16 struct le {
  17         int spt, dpt;
  18
  19         unsigned char sadr[16];
  20         unsigned char dadr[16];
  21
  22         int socket;
  23
  24         struct le* next;
  25 };
  26
  27 static struct le* le_head = 0;
  28
  29 static int look_for_child(struct ip6_tcp* pkt) {
  30         struct le* cur;
  31
  32         for(cur = le_head; cur != 0; cur = cur->next) {
  33                 if (cur->spt == pkt->data.spt &&/*{{{*/
  34                                 cur->dpt == pkt->data.spt &&
  35                                 cur->sadr[0] == pkt->hdr.sadr[0] &&
  36                                 cur->sadr[1] == pkt->hdr.sadr[1] &&
  37                                 cur->sadr[2] == pkt->hdr.sadr[2] &&
  38                                 cur->sadr[3] == pkt->hdr.sadr[3] &&
  39                                 cur->sadr[4] == pkt->hdr.sadr[4] &&
  40                                 cur->sadr[5] == pkt->hdr.sadr[5] &&
  41                                 cur->sadr[6] == pkt->hdr.sadr[6] &&
  42                                 cur->sadr[7] == pkt->hdr.sadr[7] &&
  43                                 cur->sadr[8] == pkt->hdr.sadr[8] &&
  44                                 cur->sadr[9] == pkt->hdr.sadr[9] &&
  45                                 cur->sadr[10] == pkt->hdr.sadr[10] &&
  46                                 cur->sadr[11] == pkt->hdr.sadr[11] &&
  47                                 cur->sadr[12] == pkt->hdr.sadr[12] &&
  48                                 cur->sadr[13] == pkt->hdr.sadr[13] &&
  49                                 cur->sadr[14] == pkt->hdr.sadr[14] &&
  50                                 cur->sadr[15] == pkt->hdr.sadr[15] &&
  51
  52                                 cur->dadr[0] == pkt->hdr.dadr[0] &&
  53                                 cur->dadr[1] == pkt->hdr.dadr[1] &&
  54                                 cur->dadr[2] == pkt->hdr.dadr[2] &&
  55                                 cur->dadr[3] == pkt->hdr.dadr[3] &&
  56                                 cur->dadr[4] == pkt->hdr.dadr[4] &&
  57                                 cur->dadr[5] == pkt->hdr.dadr[5] &&
  58                                 cur->dadr[6] == pkt->hdr.dadr[6] &&
  59                                 cur->dadr[7] == pkt->hdr.dadr[7] &&
  60                                 cur->dadr[8] == pkt->hdr.dadr[8] &&
  61                                 cur->dadr[9] == pkt->hdr.dadr[9] &&
  62                                 cur->dadr[10] == pkt->hdr.dadr[10] &&
  63                                 cur->dadr[11] == pkt->hdr.dadr[11] &&
  64                                 cur->dadr[12] == pkt->hdr.dadr[12] &&
  65                                 cur->dadr[13] == pkt->hdr.dadr[13] &&
  66                                 cur->dadr[14] == pkt->hdr.dadr[14] &&
  67                                 cur->dadr[15] == pkt->hdr.dadr[15])/*}}}*/
  68                         return cur->socket;
  69         }
  70         return -1;
  71 }
  72
  73 static struct le* new_le() {{{
  74         struct le* res = (struct le*) malloc(sizeof(struct le));
  75
  76         struct le** cur;
  77
  78         for(cur = &le_head; *cur != 0; cur = &((*cur)->next)) {}
  79
  80         *cur = res;
  81
  82         return res;
  83 }}}
  84
  85 static int nat(struct ip6_tcp* pkt) {{{
  86         unsigned char adr1[] = { 0x12, 0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02};
  87         unsigned char adr2[] = { 0x12, 0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03};
  88
  89         if (strncmp((char*)adr1, (char*)pkt->hdr.dadr, 16)) {
  90                 int sock = socket(AF_INET, SOCK_STREAM, 0);
  91                 struct sockaddr_in info;
  92                 memset(&info, 0, sizeof(info));
  93
  94                 info.sin_family = AF_INET;
  95                 info.sin_port = pkt->data.dpt;
  96                 inet_pton(AF_INET, "94.142.241.111", &info.sin_addr.s_addr);
  97
  98                 connect(sock, (const struct sockaddr*)&info, sizeof(info));
  99                 return sock;
 100         } else if (strncmp((char*)adr2, (char*)pkt->hdr.dadr, 16)) {
 101                 int sock = socket(AF_INET6, SOCK_STREAM, 0);
 102
 103                 struct sockaddr_in6 info;
 104                 memset(&info, 0, sizeof(info));
 105
 106                 info.sin6_family = AF_INET6;
 107                 info.sin6_port = pkt->data.dpt;
 108
 109                 inet_pton(AF_INET6, "2a02:898:17:8000::42", info.sin6_addr.s6_addr);
 110
 111                 connect(sock, (const struct sockaddr*)&info, sizeof(info));
 112
 113                 return sock;
 114         }
 115         return -1;
 116 }}}
 117
 118 void handle_tcp(struct ip6_tcp* pkt) {
 119         signal(SIGCHLD, SIG_IGN);
 120
 121         int fd = look_for_child(pkt);
 122
 123         if (fd == -1) {
 124                 struct le* le = new_le();
 125                 le->spt = pkt->data.spt;
 126                 le->dpt = pkt->data.dpt;
 127
 128                 memcpy(le->sadr, pkt->hdr.sadr, 16);
 129                 memcpy(le->dadr, pkt->hdr.dadr, 16);
 130
 131                 le->socket = nat(pkt);
 132                 fd = le->socket;
 133         }
 134
 135         int size = payload((&pkt->hdr)) - pkt->data.off;
 136
 137         int w = 0;
 138         while (size > 0) {
 139                 w = write(fd, pkt->data.data, size - w);
 140                 if (w < 0) {
 141                         debug(1, 0, "writing: %s\n", strerror(errno));
 142                 } else {
 143                         size -= w;
 144                 }
 145         }
 146 }