tor-smtp/tor-smtp.c

   1 /*
   2  * tor-smtp
   3  *
   4  * Copyright (c) 2006 Johannes Berg <johannes@sipsolutions.net>
   5  *
   6  * The bidicopy() routine is from OpenBSD's netcat rewrite, plus patches
   7  * from the fedora project.
   8  *
   9  * Copyright (c) 2001 Eric Jackson <ericj@monkey.org>
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  *
  15  * 1. Redistributions of source code must retain the above copyright
  16  *   notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *   notice, this list of conditions and the following disclaimer in the
  19  *   documentation and/or other materials provided with the distribution.
  20  * 3. The name of the author may not be used to endorse or promote products
  21  *   derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  */
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36 #include <netdb.h>
  37 #include <stdlib.h>
  38 #include <sys/poll.h>
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <errno.h>
  42 #include <unistd.h>
  43 #include <sys/time.h>
  44 #include <time.h>
  45 /* for BSD: htons is in there: */
  46 #include <arpa/inet.h>
  47 #include "atomicio.h"
  48
  49 //#define DEBUG(str,args...) fprintf(stderr, str, ##args);
  50 #define DEBUG(str,args...) do {} while(0)
  51
  52 int read_bytes_timeout(int fd, char *buf, int bytes, int timeout)
  53 {
  54 # define DEBUG_RETURN(str,args...) do { DEBUG(str, ##args); return 0; } while (0)
  55         struct pollfd pollfd = { .fd = fd, .events = POLLIN };
  56         struct timeval tv_start, tv_now;
  57         int got = 0, tmp;
  58
  59         gettimeofday(&tv_start, NULL);
  60
  61         while (got < bytes && timeout >= 0) {
  62                 if (poll(&pollfd, 1, timeout*1000) <= 0)
  63                         DEBUG_RETURN("poll failed: %d (got %d)\n", errno, got);
  64                 gettimeofday(&tv_now, NULL);
  65                 timeout -= tv_now.tv_sec - tv_start.tv_sec;
  66                 tv_start = tv_now;
  67
  68                 tmp = read(fd, buf+got, bytes-got);
  69                 if (tmp <= 0)
  70                         DEBUG_RETURN("read failed: %d\n", errno);
  71                 got += tmp;
  72         }
  73         return bytes;
  74 #undef DEBUG_RETURN
  75 }
  76
  77 int connect_via_tor(const char *tor_server, const char *tor_port,
  78                     const char *remote_server, short remote_port)
  79 {
  80         int fd;
  81         struct addrinfo *res = NULL;
  82         char socks_init[] = { 5, 1, 0 };
  83         char buf[255+7]; /* must be less than 255+7+1 bytes long */
  84         int remote_server_len = strlen(remote_server);
  85
  86         if (remote_server_len > sizeof(buf)-7/*5 leading bytes and port */)
  87                 return -1;
  88
  89         fd = socket(PF_INET, SOCK_STREAM, 0);
  90         if (fd == -1) {
  91                 DEBUG("failed to create socket\n");
  92                 return -1;
  93         }
  94
  95 #define DEBUG_OUT(str, args...) do { DEBUG(str,##args); goto out_close; } while (0)
  96
  97         if (getaddrinfo(tor_server, tor_port, NULL, &res))
  98                 DEBUG_OUT("getaddrinfo\n");
  99         if (!res)
 100                 DEBUG_OUT("getaddrinfo returned empty set\n");
 101
 102         if (connect(fd, res->ai_addr, res->ai_addrlen))
 103                 DEBUG_OUT("failed to connect\n");
 104
 105         /* now that we are connected, set up SOCKS */
 106         if (write(fd, &socks_init, sizeof(socks_init)) != sizeof(socks_init))
 107                 goto out_close;
 108         if (!read_bytes_timeout(fd, &buf[0], 2, 120))
 109                 goto out_close;
 110         if (buf[0] != 5 || buf[1] != 0)
 111                 goto out_close;
 112
 113         buf[0] = 5;
 114         buf[1] = 1;
 115         buf[2] = 0;
 116         buf[3] = 3;
 117         buf[4] = remote_server_len;
 118         strcpy(buf+5, remote_server);
 119         *(short*) (buf+5+remote_server_len) = htons(remote_port);
 120         if (write(fd, buf, 5+remote_server_len+2) != 5+remote_server_len+2)
 121                 goto out_close;
 122         if (!read_bytes_timeout(fd, buf, 4, 120))
 123                 goto out_close;
 124         if (buf[0] != 5 || buf[1] != 0)
 125                 goto out_close;
 126         /* read rest of the response */
 127         switch(buf[3]) {
 128         case 1:
 129                 if (!read_bytes_timeout(fd, buf, 6, 120))
 130                         goto out_close;
 131                 break;
 132         /* TODO handle other responses */
 133         }
 134         freeaddrinfo(res);
 135
 136         return fd;
 137  out_close:
 138         close(fd);
 139         return -1;
 140 }
 141
 142 /* read at most buflen characters into buffer,
 143  * until linefeed is encountered.
 144  * NB: if more characters are received they are discarded!
 145  */
 146 int readline(int fd, char *buf, int buflen, int timeout)
 147 {
 148 # define DEBUG_RETURN(str,args...) do { DEBUG(str, ##args); return 0; } while (0)
 149         struct pollfd pollfd = { .fd = fd, .events = POLLIN };
 150         struct timeval tv_start, tv_now;
 151         int got = 0, tmp;
 152         char *match;
 153
 154         gettimeofday(&tv_start, NULL);
 155
 156         while (got < buflen && timeout >= 0) {
 157                 if (poll(&pollfd, 1, timeout*1000) <= 0)
 158                         DEBUG_RETURN("poll failed: %d (got %d)\n", errno, got);
 159                 gettimeofday(&tv_now, NULL);
 160                 timeout -= tv_now.tv_sec - tv_start.tv_sec;
 161                 tv_start = tv_now;
 162
 163                 tmp = read(fd, buf+got, buflen-got);
 164                 if (tmp <= 0)
 165                         DEBUG_RETURN("read failed: %d\n", errno);
 166                 match = memchr(buf+got, '\n', tmp);
 167                 if (match) {
 168                         if (*(match-1) == '\r')
 169                                 match--;
 170                         *match = '\0';
 171                         return match-buf;
 172                 }
 173                 got += tmp;
 174         }
 175         return -1;
 176 #undef DEBUG_RETURN
 177 }
 178
 179 /*
 180  * readwrite()
 181  * Loop that polls on the network file descriptor and stdin.
 182  */
 183 void
 184 bidicopy(int nfd)
 185 {
 186         struct pollfd pfd[2];
 187         unsigned char buf[8192];
 188         int n, wfd = fileno(stdin);
 189         int lfd = fileno(stdout);
 190         int plen;
 191
 192         plen = 1024;
 193
 194         /* Setup Network FD */
 195         pfd[0].fd = nfd;
 196         pfd[0].events = POLLIN;
 197
 198         /* Set up STDIN FD. */
 199         pfd[1].fd = wfd;
 200         pfd[1].events = POLLIN;
 201
 202         while (pfd[0].fd != -1) {
 203                 if ((n = poll(pfd, 2, -1)) < 0) {
 204                         close(nfd);
 205                         return;
 206                 }
 207
 208                 if (n == 0)
 209                         return;
 210
 211                 if (pfd[0].revents & POLLIN) {
 212                         if ((n = read(nfd, buf, plen)) < 0)
 213                                 return;
 214                         else if (n == 0) {
 215                                 goto shutdown_rd;
 216                         } else {
 217                                 if (atomicio(vwrite, lfd, buf, n) != n)
 218                                         return;
 219                         }
 220                 }
 221                 else if (pfd[0].revents & POLLHUP) {
 222                 shutdown_rd:
 223                         shutdown(nfd, SHUT_RD);
 224                         pfd[0].fd = -1;
 225                         pfd[0].events = 0;
 226                 }
 227
 228                 if (1) {
 229                     if(pfd[1].revents & POLLIN) {
 230                         if ((n = read(wfd, buf, plen)) < 0)
 231                                 return;
 232                         else if (n == 0) {
 233                                 goto shutdown_wr;
 234                         } else {
 235                                 if (atomicio(vwrite, nfd, buf, n) != n)
 236                                         return;
 237                         }
 238                     }
 239                     else if (pfd[1].revents & POLLHUP) {
 240                     shutdown_wr:
 241                         shutdown(nfd, SHUT_WR);
 242                         pfd[1].fd = -1;
 243                         pfd[1].events = 0;
 244                     }
 245                 }
 246         }
 247 }
 248
 249 int main(int argc, char **argv)
 250 {
 251         char *tor_server = "localhost";
 252         char *tor_port = "9050";
 253         char *remote_server = NULL;
 254         char *tmp;
 255         char local_onion[255];
 256         char buf[255], buf2[255];
 257         int linelen;
 258         int fd;
 259
 260         if (argc >= 2)
 261                 tor_server = argv[1];
 262         if (argc >= 3)
 263                 tor_port = argv[2];
 264         if (argc > 3 || (tor_server && (!strcasecmp(tor_server, "--help") || !strcasecmp(tor_server, "-h")))) {
 265                 fprintf(stderr, "tor-smtp [tor-server] [tor-port]\n");
 266                 fprintf(stderr, "     (default localhost 9050)\n");
 267                 return 2;
 268         }
 269
 270         printf("220 Welcome\r\n");
 271         fflush(stdout);
 272
 273  command:
 274         if ((linelen = readline(0, buf, sizeof(buf), 30)) < 0) {
 275                 printf("421 connection timed out\r\n");
 276                 fflush(stdout);
 277                 return 0;
 278         }
 279         if (linelen < 4) {
 280                 goto invalid;
 281         }
 282         if (!strncasecmp("QUIT", buf, 4)) {
 283                 printf("221 closing connection\r\n");
 284                 fflush(stdout);
 285                 return 0;
 286         }
 287         if (!strncasecmp("EHLO ", buf, 5) || !strncasecmp("HELO ", buf, 5))
 288                 goto helo_continue;
 289  invalid:
 290         printf("500 invalid command\r\n");
 291         fflush(stdout);
 292         goto command;
 293
 294  helo_continue:
 295         tmp = strtok(buf+5, " ");
 296         if (!tmp) {
 297                 printf("500 invalid EHLO/HELO: missing local name\n");
 298                 fflush(stdout);
 299                 goto command;
 300         }
 301         remote_server = strtok(NULL, " ");
 302         if (!remote_server) {
 303                 printf("500 invalid EHLO/HELO: missing remote name\n");
 304                 goto command;
 305         }
 306         strncpy(local_onion, tmp, sizeof(local_onion));
 307         fd = connect_via_tor(tor_server, tor_port, remote_server, 25);
 308         if (fd < 0) {
 309                 printf("421 could not connect\r\n");
 310                 fflush(stdout);
 311                 return 0;
 312         }
 313
 314         linelen = readline(fd, buf2, sizeof(buf2), 120);
 315         if (linelen < 0) {
 316                 printf("421 could not connect\r\n");
 317                 fflush(stdout);
 318                 return 0;
 319         }
 320         if (strncmp("220 ", buf2, 4)) {
 321                 printf("421 server seems to not like us\r\n");
 322                 DEBUG("answer was: %s\n", buf2);
 323                 fflush(stdout);
 324                 return 0;
 325         }
 326
 327         strncpy(buf+5, local_onion, sizeof(buf)-5);
 328         linelen = strlen(buf);
 329         *(buf+linelen) = '\r';
 330         *(buf+linelen+1) = '\n';
 331         write(fd, buf, linelen+2);
 332
 333         close(2); /* get rid of stderr */
 334         /* now "all" we have to do is do a bidirectional copy of fd and stdio */
 335         bidicopy(fd);
 336         return 0;
 337 }