sys/src/cmd/ip/socksd.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <ip.h>
   4
   5 int socksver;
   6
   7 int
   8 str2addr(char *s, uchar *a)
   9 {
  10         uchar *a0, ip[16];
  11         char *p;
  12
  13         if((s = strchr(s, '!')) == nil)
  14                 return 0;
  15         if((p = strchr(++s, '!')) == nil)
  16                 return 0;
  17         if(strchr(++p, '!') != nil)
  18                 return 0;
  19         if(parseip(ip, s) == -1)
  20                 return 0;
  21
  22         a0 = a;
  23         if(socksver == 4){
  24                 a += 2;
  25                 hnputs(a, atoi(p));
  26                 a += 2;
  27                 v6tov4(a, ip);
  28                 a += 4;
  29         } else {
  30                 a += 3;
  31                 if(isv4(ip)){
  32                         *a++ = 0x01;
  33                         v6tov4(a, ip);
  34                         a += 4;
  35                 } else {
  36                         *a++ = 0x04;
  37                         memmove(a, ip, 16);
  38                         a += 16;
  39                 }
  40                 hnputs(a, atoi(p));
  41                 a += 2;
  42         }
  43         return a - a0;
  44 }
  45
  46 char*
  47 addr2str(char *proto, uchar *a){
  48         static char s[128];
  49         uchar ip[16];
  50         int n, port;
  51
  52         if(socksver == 4){
  53                 a += 2;
  54                 port = nhgets(a);
  55                 a += 2;
  56                 if((a[0] | a[1] | a[2]) == 0 && a[3]){
  57                         a += 4;
  58                         a += strlen((char*)a)+1;
  59                         snprint(s, sizeof(s), "%s!%s!%d", proto, (char*)a, port);
  60                         return s;
  61                 }
  62                 v4tov6(ip, a);
  63         } else {
  64                 a += 3;
  65                 switch(*a++){
  66                 default:
  67                         return nil;
  68                 case 0x01:
  69                         v4tov6(ip, a);
  70                         port = nhgets(a+4);
  71                         break;
  72                 case 0x04:
  73                         memmove(ip, a, 16);
  74                         port = nhgets(a+16);
  75                         break;
  76                 case 0x03:
  77                         n = *a++;
  78                         port = nhgets(a+n);
  79                         snprint(s, sizeof(s), "%s!%.*s!%d", proto, n, (char*)a, port);
  80                         return s;
  81                 }
  82         }
  83         snprint(s, sizeof(s), "%s!%I!%d", proto, ip, port);
  84         return s;
  85 }
  86
  87 int
  88 sockerr(int err)
  89 {
  90         /* general error */
  91         if(socksver == 4)
  92                 return err ? 0x5b : 0x5a;
  93         else
  94                 return err != 0;
  95 }
  96
  97 void
  98 main(int argc, char *argv[])
  99 {
 100         uchar buf[8*1024], *p;
 101         char dir[40], *s;
 102         NetConnInfo *nc;
 103         int fd, n;
 104
 105         fmtinstall('I', eipfmt);
 106
 107         ARGBEGIN {
 108         } ARGEND;
 109
 110         /* ver+cmd or ver+nmethod */
 111         if(readn(0, buf, 2) != 2)
 112                 return;
 113         socksver = buf[0];
 114         if(socksver < 4)
 115                 return;
 116         if(socksver > 5)
 117                 socksver = 5;
 118
 119         if(socksver == 4){
 120                 /* port+ip4 */
 121                 if(readn(0, buf+2, 2+4) != 2+4)
 122                         return;
 123                 /* +user\0 */
 124                 for(p = buf+2+2+4;; p++){
 125                         if(p >= buf+sizeof(buf))
 126                                 return;
 127                         if(read(0, p, 1) != 1)
 128                                 return;
 129                         if(*p == 0)
 130                                 break;
 131                 }
 132                 /* socks 4a dom hack */
 133                 if((buf[4] | buf[5] | buf[6]) == 0 && buf[7]){
 134                         /* +dom\0 */
 135                         for(++p;; p++){
 136                                 if(p >= buf+sizeof(buf))
 137                                         return;
 138                                 if(read(0, p, 1) != 1)
 139                                         return;
 140                                 if(*p == 0)
 141                                         break;
 142                         }
 143                 }
 144         } else {
 145                 /* nmethod */
 146                 if((n = buf[1]) > 0)
 147                         if(readn(0, buf+2, n) != n)
 148                                 return;
 149
 150                 /* ver+method */
 151                 buf[0] = socksver;
 152                 buf[1] = 0x00;  /* no authentication required */
 153                 if(write(1, buf, 2) != 2)
 154                         return;
 155
 156                 /* ver+cmd+res+atyp */
 157                 if(readn(0, buf, 4) != 4)
 158                         return;
 159                 switch(buf[3]){
 160                 default:
 161                         return;
 162                 case 0x01:      /* +ipv4 */
 163                         if(readn(0, buf+4, 4+2) != 4+2)
 164                                 return;
 165                         break;
 166                 case 0x03:      /* +len+dom[len] */
 167                         if(readn(0, buf+4, 1) != 1)
 168                                 return;
 169                         if((n = buf[4]) == 0)
 170                                 return;
 171                         if(readn(0, buf+5, n+2) != n+2)
 172                                 return;
 173                         break;
 174                 case 0x04:      /* +ipv6 */
 175                         if(readn(0, buf+4, 16+2) != 16+2)
 176                                 return;
 177                         break;
 178                 }
 179         }
 180
 181         nc = nil;
 182         dir[0] = 0;
 183         fd = -1;
 184         switch(buf[1]){
 185         case 0x01:      /* CONNECT */
 186                 if((s = addr2str("tcp", buf)) == nil)
 187                         return;
 188                 fd = dial(s, 0, dir, 0);
 189                 break;
 190         }
 191
 192         if(fd >= 0){
 193                 if((nc = getnetconninfo(dir, -1)) == nil){
 194                         close(fd);
 195                         fd = -1;
 196                 }
 197         }
 198
 199         /* reply */
 200         buf[1] = sockerr(fd < 0);                       /* status */
 201         if(socksver == 4){
 202                 buf[0] = 0x00;                          /* vc */
 203                 if(fd < 0){
 204                         memset(buf+2, 0, 2+4);
 205                         write(1, buf, 2+2+4);
 206                         return;
 207                 }
 208         } else {
 209                 buf[0] = socksver;                      /* ver */
 210                 buf[2] = 0x00;                          /* res */
 211                 if(fd < 0){
 212                         buf[3] = 0x01;                  /* atyp */
 213                         memset(buf+4, 0, 4+2);
 214                         write(1, buf, 4+4+2);
 215                         return;
 216                 }
 217         }
 218         if((n = str2addr(nc->laddr, buf)) <= 0)
 219                 return;
 220         if(write(1, buf, n) != n)
 221                 return;
 222
 223         /* relay data */
 224         switch(rfork(RFMEM|RFPROC|RFFDG|RFNOWAIT)){
 225         case -1:
 226                 return;
 227         case 0:
 228                 dup(fd, 0);
 229                 break;
 230         default:
 231                 dup(fd, 1);
 232         }
 233         while((n = read(0, buf, sizeof(buf))) > 0)
 234                 if(write(1, buf, n) != n)
 235                         break;
 236         postnote(PNGROUP, getpid(), "kill");
 237         exits(0);
 238 }
 239