mdw@git.distorted.org.uk Git - tripe/blob - pkstream/pkstream.c

   1 /* -*-c-*-
   2  *
   3  * Forwarding UDP packets over a stream
   4  *
   5  * (c) 2003 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software: you can redistribute it and/or modify it under
  13  * the terms of the GNU General Public License as published by the Free
  14  * Software Foundation; either version 3 of the License, or (at your
  15  * option) any later version.
  16  *
  17  * TrIPE is distributed in the hope that it will be useful, but WITHOUT
  18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  20  * for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE.  If not, see <https://www.gnu.org/licenses/>.
  24  */
  25
  26 /*----- Header files ------------------------------------------------------*/
  27
  28 #include "config.h"
  29
  30 #include <ctype.h>
  31 #include <errno.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35
  36 #include <sys/time.h>
  37 #include <sys/types.h>
  38 #include <unistd.h>
  39 #include <fcntl.h>
  40 #include <sys/uio.h>
  41 #include <sys/socket.h>
  42 #include <netinet/in.h>
  43 #include <arpa/inet.h>
  44 #include <netdb.h>
  45
  46 #include <mLib/alloc.h>
  47 #include <mLib/bits.h>
  48 #include <mLib/dstr.h>
  49 #include <mLib/fdflags.h>
  50 #include <mLib/mdwopt.h>
  51 #include <mLib/quis.h>
  52 #include <mLib/report.h>
  53 #include <mLib/sel.h>
  54 #include <mLib/selpk.h>
  55
  56 #include "util.h"
  57
  58 /*----- Data structures ---------------------------------------------------*/
  59
  60 typedef union addr {
  61   struct sockaddr sa;
  62   struct sockaddr_in sin;
  63 } addr;
  64
  65 typedef struct pk {
  66   struct pk *next;                      /* Next packet in the chain */
  67   octet *p, *o;                         /* Buffer start and current posn */
  68   size_t n;                             /* Size of packet remaining */
  69 } pk;
  70
  71 typedef struct pkstream {
  72   unsigned f;                           /* Flags... */
  73 #define PKF_FULL 1u                     /*   Buffer is full: stop reading */
  74   sel_file r, w;                        /* Read and write selectors */
  75   pk *pks, **pk_tail;                   /* Packet queue */
  76   size_t npk, szpk;                     /* Number and size of data */
  77   selpk p;                              /* Packet parser */
  78 } pkstream;
  79
  80 typedef struct connwait {
  81   unsigned f;                           /* Various flags */
  82 #define cwf_port 1u                     /*   Port is defined => listen */
  83   sel_file a;                           /* Selector */
  84   addr me, peer;                       /* Who I'm meant to be; who peer is */
  85 } connwait;
  86
  87 /*----- Static variables --------------------------------------------------*/
  88
  89 static sel_state sel;
  90 static connwait cw;
  91 static int fd_udp;
  92 static size_t pk_nmax = 128, pk_szmax = 1024*1024;
  93
  94 /*----- Main code ---------------------------------------------------------*/
  95
  96 static int nonblockify(int fd)
  97   { return (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)); }
  98
  99 static int cloexec(int fd)
 100   { return (fdflags(fd, 0, 0, FD_CLOEXEC, FD_CLOEXEC)); }
 101
 102 static socklen_t addrsz(const addr *a)
 103 {
 104   switch (a->sa.sa_family) {
 105     case AF_INET: return sizeof(a->sin);
 106     default: abort();
 107   }
 108 }
 109
 110 static const char *addrstr(const addr *a)
 111 {
 112   static char buf[128];
 113   socklen_t n = sizeof(buf);
 114
 115   if (getnameinfo(&a->sa, addrsz(a), buf, n, 0, 0, NI_NUMERICHOST))
 116     return ("<addrstr failed>");
 117   return (buf);
 118 }
 119
 120 static int addreq(const addr *a, const addr *b)
 121 {
 122   if (a->sa.sa_family != b->sa.sa_family) return (0);
 123   switch (a->sa.sa_family) {
 124     case AF_INET:
 125       return (a->sin.sin_addr.s_addr == b->sin.sin_addr.s_addr);
 126     default:
 127       abort();
 128   }
 129 }
 130
 131 static void initaddr(addr *a)
 132 {
 133   a->sin.sin_family = AF_INET;
 134   a->sin.sin_addr.s_addr = INADDR_ANY;
 135   a->sin.sin_port = 0;
 136 }
 137
 138 static void dolisten(void);
 139
 140 static void doclose(pkstream *p)
 141 {
 142   pk *pk, *ppk;
 143   close(p->w.fd);
 144   close(p->p.reader.fd);
 145   selpk_destroy(&p->p);
 146   if (!(p->f&PKF_FULL)) sel_rmfile(&p->r);
 147   if (p->npk) sel_rmfile(&p->w);
 148   for (pk = p->pks; pk; pk = ppk) {
 149     ppk = pk->next;
 150     xfree(pk->p);
 151     xfree(pk);
 152   }
 153   xfree(p);
 154   if (cw.f&cwf_port) dolisten();
 155   else exit(0);
 156 }
 157
 158 static void rdtcp(octet *b, size_t sz, pkbuf *pk, size_t *k, void *vp)
 159 {
 160   pkstream *p = vp;
 161   size_t pksz;
 162
 163   if (!sz) { doclose(p); return; }
 164   pksz = LOAD16(b);
 165   if (pksz + 2 == sz) {
 166     DISCARD(write(fd_udp, b + 2, pksz));
 167     selpk_want(&p->p, 2);
 168   } else {
 169     selpk_want(&p->p, pksz + 2);
 170     *k = sz;
 171   }
 172 }
 173
 174 static void wrtcp(int fd, unsigned mode, void *vp)
 175 {
 176 #define NPK 16
 177   struct iovec iov[NPK];
 178   pkstream *p = vp;
 179   size_t i;
 180   ssize_t n;
 181   pk *pk, *ppk;
 182
 183   for (i = 0, pk = p->pks; i < NPK && pk; i++, pk = pk->next) {
 184     iov[i].iov_base = pk->o;
 185     iov[i].iov_len = pk->n;
 186   }
 187
 188   if ((n = writev(fd, iov, i)) < 0) {
 189     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 190     moan("couldn't write to TCP socket: %s", strerror(errno));
 191     doclose(p);
 192     return;
 193   }
 194
 195   p->szpk -= n;
 196   for (pk = p->pks; n && pk; pk = ppk) {
 197     ppk = pk->next;
 198     if (pk->n <= n) {
 199       p->npk--;
 200       n -= pk->n;
 201       xfree(pk->p);
 202       xfree(pk);
 203     } else {
 204       pk->n -= n;
 205       pk->o += n;
 206       break;
 207     }
 208   }
 209   p->pks = pk;
 210   if (!pk) { p->pk_tail = &p->pks; sel_rmfile(&p->w); }
 211   if ((p->f&PKF_FULL) && p->npk < pk_nmax && p->szpk < pk_szmax)
 212     { p->f &= ~PKF_FULL; sel_addfile(&p->r); }
 213 }
 214
 215 static void rdudp(int fd, unsigned mode, void *vp)
 216 {
 217   octet buf[65536];
 218   ssize_t n;
 219   pkstream *p = vp;
 220   pk *pk;
 221
 222   if ((n = read(fd, buf, sizeof(buf))) < 0) {
 223     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
 224       return;
 225     moan("couldn't read from UDP socket: %s", strerror(errno));
 226     return;
 227   }
 228   pk = xmalloc(sizeof(*pk));
 229   pk->next = 0;
 230   pk->p = xmalloc(n + 2);
 231   STORE16(pk->p, n);
 232   memcpy(pk->p + 2, buf, n);
 233   pk->o = pk->p;
 234   pk->n = n + 2;
 235   *p->pk_tail = pk;
 236   p->pk_tail = &pk->next;
 237   if (!p->npk) sel_addfile(&p->w);
 238   sel_force(&p->w);
 239   p->npk++;
 240   p->szpk += n + 2;
 241   if (p->npk >= pk_nmax || p->szpk >= pk_szmax)
 242     { sel_rmfile(&p->r); p->f |= PKF_FULL; }
 243 }
 244
 245 static void dofwd(int fd_in, int fd_out)
 246 {
 247   pkstream *p = xmalloc(sizeof(*p));
 248   sel_initfile(&sel, &p->r, fd_udp, SEL_READ, rdudp, p);
 249   sel_initfile(&sel, &p->w, fd_out, SEL_WRITE, wrtcp, p);
 250   selpk_init(&p->p, &sel, fd_in, rdtcp, p);
 251   selpk_want(&p->p, 2);
 252   p->pks = 0;
 253   p->pk_tail = &p->pks;
 254   p->npk = p->szpk = 0;
 255   p->f = 0;
 256   sel_addfile(&p->r);
 257 }
 258
 259 static void doaccept(int fd_s, unsigned mode, void *p)
 260 {
 261   int fd;
 262   addr a;
 263   socklen_t sz = sizeof(a);
 264
 265   if ((fd = accept(fd_s, &a.sa, &sz)) < 0) {
 266     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 267     moan("couldn't accept incoming connection: %s", strerror(errno));
 268     return;
 269   }
 270   if (cw.peer.sin.sin_addr.s_addr != INADDR_ANY && !addreq(&a, &cw.peer)) {
 271     moan("rejecting connection from %s", addrstr(&a));
 272     close(fd); return;
 273   }
 274   if (nonblockify(fd) || cloexec(fd)) {
 275     moan("couldn't accept incoming connection: %s", strerror(errno));
 276     close(fd); return;
 277   }
 278   dofwd(fd, fd);
 279   close(fd_s);
 280   sel_rmfile(&cw.a);
 281 }
 282
 283 static void dolisten(void)
 284 {
 285   int fd;
 286   int opt = 1;
 287
 288   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0 ||
 289       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) ||
 290       bind(fd, &cw.me.sa, addrsz(&cw.me)) ||
 291       listen(fd, 1) || nonblockify(fd) || cloexec(fd))
 292     die(1, "couldn't set up listening socket: %s", strerror(errno));
 293   sel_initfile(&sel, &cw.a, fd, SEL_READ, doaccept, 0);
 294   sel_addfile(&cw.a);
 295 }
 296
 297 #define paf_parse 1u
 298 static void parseaddr(const char *host, const char *svc, unsigned f, addr *a)
 299 {
 300   char *alloc = 0, *sep;
 301   struct hostent *h;
 302   struct servent *s;
 303   char *qq;
 304   unsigned long n;
 305
 306   if (f&paf_parse) {
 307     alloc = xstrdup(host);
 308     if ((sep = strchr(alloc, ':')) == 0)
 309       die(1, "missing port number in address `%s'", host);
 310     host = alloc; *sep = 0; svc = sep + 1;
 311   }
 312
 313   if (host) {
 314     if ((h = gethostbyname(host)) == 0) die(1, "unknown host `%s'", host);
 315     memcpy(&a->sin.sin_addr, h->h_addr, sizeof(a->sin.sin_addr));
 316   }
 317
 318   if (svc) {
 319     if ((n = strtoul(svc, &qq, 0)) > 0 && !*qq && n <= 0xffff)
 320       a->sin.sin_port = htons(n);
 321     else if ((s = getservbyname(svc, "tcp")) != 0)
 322       a->sin.sin_port = s->s_port;
 323     else
 324       die(1, "bad service name/number `%s'", svc);
 325   }
 326
 327   xfree(alloc);
 328 }
 329
 330 static void usage(FILE *fp)
 331 {
 332   pquis(fp,
 333         "Usage: $ [-l PORT] [-b ADDR] [-p ADDR] [-c ADDR:PORT]\n\
 334         ADDR:PORT ADDR:PORT\n");
 335 }
 336
 337 static void version(FILE *fp)
 338   { pquis(fp, "$, tripe version " VERSION "\n"); }
 339
 340 static void help(FILE *fp)
 341 {
 342   version(fp);
 343   fputc('\n', fp);
 344   usage(fp);
 345   fputs("\n\
 346 Options:\n\
 347 \n\
 348 -h, --help              Display this help text.\n\
 349 -v, --version           Display version number.\n\
 350 -u, --usage             Display pointless usage message.\n\
 351 \n\
 352 -l, --listen=PORT       Listen for connections to TCP PORT.\n\
 353 -p, --peer=ADDR         Only accept connections from IP ADDR.\n\
 354 -b, --bind=ADDR         Bind to ADDR before connecting.\n\
 355 -c, --connect=ADDR:PORT Connect to IP ADDR, TCP PORT.\n\
 356 \n\
 357 Forwards UDP packets over a reliable stream.  By default, uses stdin and\n\
 358 stdout; though it can use TCP sockets instead.\n\
 359 ", fp);
 360 }
 361
 362 int main(int argc, char *argv[])
 363 {
 364   unsigned f = 0;
 365   const char *bindhost = 0, *bindsvc = 0, *peerhost = 0;
 366   addr bindaddr;
 367   const char *connhost = 0;
 368   addr tmpaddr;
 369   int fd = -1;
 370   int len = 65536;
 371
 372 #define f_bogus 1u
 373
 374   cw.f = 0;
 375
 376   ego(argv[0]);
 377   sel_init(&sel);
 378   for (;;) {
 379     static struct option opt[] = {
 380       { "help",                 0,              0,      'h' },
 381       { "version",              0,              0,      'v' },
 382       { "usage",                0,              0,      'u' },
 383       { "listen",               OPTF_ARGREQ,    0,      'l' },
 384       { "peer",                 OPTF_ARGREQ,    0,      'p' },
 385       { "bind",                 OPTF_ARGREQ,    0,      'b' },
 386       { "connect",              OPTF_ARGREQ,    0,      'c' },
 387       { 0,                      0,              0,      0 }
 388     };
 389     int i;
 390
 391     i = mdwopt(argc, argv, "hvul:p:b:c:", opt, 0, 0, 0);
 392     if (i < 0)
 393       break;
 394     switch (i) {
 395       case 'h': help(stdout); exit(0);
 396       case 'v': version(stdout); exit(0);
 397       case 'u': usage(stdout); exit(0);
 398       case 'l': bindsvc = optarg; break;
 399       case 'p': peerhost = optarg; break;
 400       case 'b': bindhost = optarg; break;
 401       case 'c': connhost = optarg; break;
 402       default: f |= f_bogus; break;
 403     }
 404   }
 405   if (optind + 2 != argc || (f&f_bogus)) { usage(stderr); exit(1); }
 406
 407   if (bindhost && !bindsvc && !connhost)
 408     die(1, "bind addr only makes sense when listening or connecting");
 409   if (peerhost && !bindsvc)
 410     die(1, "peer addr only makes sense when listening");
 411   if (bindsvc && connhost)
 412     die(1, "can't listen and connect");
 413
 414   if (bindhost || bindsvc) {
 415     initaddr(&bindaddr);
 416     if (!bindsvc) parseaddr(bindhost, 0, 0, &bindaddr);
 417     else {
 418       initaddr(&cw.me);
 419       parseaddr(bindhost, bindsvc, 0, &cw.me);
 420       cw.f |= cwf_port;
 421     }
 422   }
 423
 424   initaddr(&cw.peer);
 425   if (peerhost) parseaddr(peerhost, 0, 0, &cw.peer);
 426
 427   if (connhost) {
 428     initaddr(&tmpaddr);
 429     parseaddr(connhost, 0, paf_parse, &tmpaddr);
 430     if ((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0 ||
 431         (bindhost &&
 432          bind(fd, &bindaddr.sa, addrsz(&bindaddr))) ||
 433         connect(fd, &tmpaddr.sa, addrsz(&tmpaddr)))
 434       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 435     if (nonblockify(fd) || cloexec(fd))
 436       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 437   }
 438
 439   initaddr(&tmpaddr);
 440   parseaddr(argv[optind], 0, paf_parse, &tmpaddr);
 441   if ((fd_udp = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0 ||
 442       nonblockify(fd_udp) || cloexec(fd_udp) ||
 443       setsockopt(fd_udp, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 444       setsockopt(fd_udp, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)) ||
 445       bind(fd_udp, &tmpaddr.sa, addrsz(&tmpaddr)))
 446     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 447   initaddr(&tmpaddr);
 448   parseaddr(argv[optind + 1], 0, paf_parse, &tmpaddr);
 449   if (connect(fd_udp, &tmpaddr.sa, addrsz(&tmpaddr)))
 450     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 451
 452   if (bindsvc) dolisten();
 453   else if (connhost) dofwd(fd, fd);
 454   else dofwd(STDIN_FILENO, STDOUT_FILENO);
 455
 456   for (;;) {
 457     if (sel_select(&sel) && errno != EINTR)
 458       die(1, "select failed: %s", strerror(errno));
 459   }
 460   return (0);
 461 }
 462
 463 /*----- That's all, folks -------------------------------------------------*/