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/darray.h>
  49 #include <mLib/dstr.h>
  50 #include <mLib/fdflags.h>
  51 #include <mLib/mdwopt.h>
  52 #include <mLib/quis.h>
  53 #include <mLib/report.h>
  54 #include <mLib/sel.h>
  55 #include <mLib/selpk.h>
  56
  57 #include "util.h"
  58
  59 /*----- Data structures ---------------------------------------------------*/
  60
  61 typedef union addr {
  62   struct sockaddr sa;
  63   struct sockaddr_in sin;
  64 } addr;
  65
  66 DA_DECL(addr_v, addr);
  67 DA_DECL(str_v, const char *);
  68
  69 typedef struct pk {
  70   struct pk *next;                      /* Next packet in the chain */
  71   octet *p, *o;                         /* Buffer start and current posn */
  72   size_t n;                             /* Size of packet remaining */
  73 } pk;
  74
  75 typedef struct pkstream {
  76   unsigned f;                           /* Flags... */
  77 #define PKF_FULL 1u                     /*   Buffer is full: stop reading */
  78   sel_file r, w;                        /* Read and write selectors */
  79   pk *pks, **pk_tail;                   /* Packet queue */
  80   size_t npk, szpk;                     /* Number and size of data */
  81   selpk p;                              /* Packet parser */
  82 } pkstream;
  83
  84 typedef struct connwait {
  85   unsigned f;                           /* Various flags */
  86 #define cwf_port 1u                     /*   Port is defined => listen */
  87   sel_file *sfv;                        /* Selectors */
  88   addr_v me, peer;                     /* Who I'm meant to be; who peer is */
  89 } connwait;
  90
  91 /*----- Static variables --------------------------------------------------*/
  92
  93 static sel_state sel;
  94 static connwait cw;
  95 static int fd_udp;
  96 static size_t pk_nmax = 128, pk_szmax = 1024*1024;
  97
  98 /*----- Main code ---------------------------------------------------------*/
  99
 100 static int nonblockify(int fd)
 101   { return (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)); }
 102
 103 static int cloexec(int fd)
 104   { return (fdflags(fd, 0, 0, FD_CLOEXEC, FD_CLOEXEC)); }
 105
 106 static socklen_t addrsz(const addr *a)
 107 {
 108   switch (a->sa.sa_family) {
 109     case AF_INET: return sizeof(a->sin);
 110     default: abort();
 111   }
 112 }
 113
 114 static int knownafp(int af)
 115 {
 116   switch (af) {
 117     case AF_INET: return (1);
 118     default: return (0);
 119   }
 120 }
 121
 122 static int initsock(int fd, int af)
 123 {
 124   switch (af) {
 125     case AF_INET: break;
 126     default: abort();
 127   }
 128   return (0);
 129 }
 130
 131 static const char *addrstr(const addr *a)
 132 {
 133   static char buf[128];
 134   socklen_t n = sizeof(buf);
 135
 136   if (getnameinfo(&a->sa, addrsz(a), buf, n, 0, 0, NI_NUMERICHOST))
 137     return ("<addrstr failed>");
 138   return (buf);
 139 }
 140
 141 static int addreq(const addr *a, const addr *b)
 142 {
 143   if (a->sa.sa_family != b->sa.sa_family) return (0);
 144   switch (a->sa.sa_family) {
 145     case AF_INET:
 146       return (a->sin.sin_addr.s_addr == b->sin.sin_addr.s_addr);
 147     default:
 148       abort();
 149   }
 150 }
 151
 152 static void initaddr(addr *a, int af)
 153 {
 154   a->sa.sa_family = af;
 155   switch (af) {
 156     case AF_INET:
 157       a->sin.sin_addr.s_addr = INADDR_ANY;
 158       a->sin.sin_port = 0;
 159       break;
 160     default:
 161       abort();
 162   }
 163 }
 164
 165 #define caf_addr 1u
 166 #define caf_port 2u
 167 static void copyaddr(addr *a, const struct sockaddr *sa, unsigned f)
 168 {
 169   const struct sockaddr_in *sin;
 170
 171   a->sa.sa_family = sa->sa_family;
 172   switch (sa->sa_family) {
 173     case AF_INET:
 174       sin = (const struct sockaddr_in *)sa;
 175       if (f&caf_addr) a->sin.sin_addr = sin->sin_addr;
 176       if (f&caf_port) a->sin.sin_port = sin->sin_port;
 177       break;
 178     default:
 179       abort();
 180   }
 181 }
 182
 183 static void dolisten(void);
 184
 185 static void doclose(pkstream *p)
 186 {
 187   pk *pk, *ppk;
 188   close(p->w.fd);
 189   close(p->p.reader.fd);
 190   selpk_destroy(&p->p);
 191   if (!(p->f&PKF_FULL)) sel_rmfile(&p->r);
 192   if (p->npk) sel_rmfile(&p->w);
 193   for (pk = p->pks; pk; pk = ppk) {
 194     ppk = pk->next;
 195     xfree(pk->p);
 196     xfree(pk);
 197   }
 198   xfree(p);
 199   if (cw.f&cwf_port) dolisten();
 200   else exit(0);
 201 }
 202
 203 static void rdtcp(octet *b, size_t sz, pkbuf *pk, size_t *k, void *vp)
 204 {
 205   pkstream *p = vp;
 206   size_t pksz;
 207
 208   if (!sz) { doclose(p); return; }
 209   pksz = LOAD16(b);
 210   if (pksz + 2 == sz) {
 211     DISCARD(write(fd_udp, b + 2, pksz));
 212     selpk_want(&p->p, 2);
 213   } else {
 214     selpk_want(&p->p, pksz + 2);
 215     *k = sz;
 216   }
 217 }
 218
 219 static void wrtcp(int fd, unsigned mode, void *vp)
 220 {
 221 #define NPK 16
 222   struct iovec iov[NPK];
 223   pkstream *p = vp;
 224   size_t i;
 225   ssize_t n;
 226   pk *pk, *ppk;
 227
 228   for (i = 0, pk = p->pks; i < NPK && pk; i++, pk = pk->next) {
 229     iov[i].iov_base = pk->o;
 230     iov[i].iov_len = pk->n;
 231   }
 232
 233   if ((n = writev(fd, iov, i)) < 0) {
 234     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 235     moan("couldn't write to TCP socket: %s", strerror(errno));
 236     doclose(p);
 237     return;
 238   }
 239
 240   p->szpk -= n;
 241   for (pk = p->pks; n && pk; pk = ppk) {
 242     ppk = pk->next;
 243     if (pk->n <= n) {
 244       p->npk--;
 245       n -= pk->n;
 246       xfree(pk->p);
 247       xfree(pk);
 248     } else {
 249       pk->n -= n;
 250       pk->o += n;
 251       break;
 252     }
 253   }
 254   p->pks = pk;
 255   if (!pk) { p->pk_tail = &p->pks; sel_rmfile(&p->w); }
 256   if ((p->f&PKF_FULL) && p->npk < pk_nmax && p->szpk < pk_szmax)
 257     { p->f &= ~PKF_FULL; sel_addfile(&p->r); }
 258 }
 259
 260 static void rdudp(int fd, unsigned mode, void *vp)
 261 {
 262   octet buf[65536];
 263   ssize_t n;
 264   pkstream *p = vp;
 265   pk *pk;
 266
 267   if ((n = read(fd, buf, sizeof(buf))) < 0) {
 268     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
 269       return;
 270     moan("couldn't read from UDP socket: %s", strerror(errno));
 271     return;
 272   }
 273   pk = xmalloc(sizeof(*pk));
 274   pk->next = 0;
 275   pk->p = xmalloc(n + 2);
 276   STORE16(pk->p, n);
 277   memcpy(pk->p + 2, buf, n);
 278   pk->o = pk->p;
 279   pk->n = n + 2;
 280   *p->pk_tail = pk;
 281   p->pk_tail = &pk->next;
 282   if (!p->npk) sel_addfile(&p->w);
 283   sel_force(&p->w);
 284   p->npk++;
 285   p->szpk += n + 2;
 286   if (p->npk >= pk_nmax || p->szpk >= pk_szmax)
 287     { sel_rmfile(&p->r); p->f |= PKF_FULL; }
 288 }
 289
 290 static void dofwd(int fd_in, int fd_out)
 291 {
 292   pkstream *p = xmalloc(sizeof(*p));
 293   sel_initfile(&sel, &p->r, fd_udp, SEL_READ, rdudp, p);
 294   sel_initfile(&sel, &p->w, fd_out, SEL_WRITE, wrtcp, p);
 295   selpk_init(&p->p, &sel, fd_in, rdtcp, p);
 296   selpk_want(&p->p, 2);
 297   p->pks = 0;
 298   p->pk_tail = &p->pks;
 299   p->npk = p->szpk = 0;
 300   p->f = 0;
 301   sel_addfile(&p->r);
 302 }
 303
 304 static void doaccept(int fd_s, unsigned mode, void *p)
 305 {
 306   int fd;
 307   addr a;
 308   socklen_t sz = sizeof(a);
 309   size_t i, n;
 310
 311   if ((fd = accept(fd_s, &a.sa, &sz)) < 0) {
 312     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 313     moan("couldn't accept incoming connection: %s", strerror(errno));
 314     return;
 315   }
 316   n = DA_LEN(&cw.peer);
 317   if (!n) goto match;
 318   for (i = 0; i < n; i++) if (addreq(&a, &DA(&cw.peer)[i])) goto match;
 319   moan("rejecting connection from %s", addrstr(&a));
 320   close(fd); return;
 321 match:
 322   if (nonblockify(fd) || cloexec(fd)) {
 323     moan("couldn't accept incoming connection: %s", strerror(errno));
 324     close(fd); return;
 325   }
 326   dofwd(fd, fd);
 327   n = DA_LEN(&cw.me);
 328   for (i = 0; i < n; i++) { close(cw.sfv[i].fd); sel_rmfile(&cw.sfv[i]); }
 329 }
 330
 331 static void dolisten1(const addr *a, sel_file *sf)
 332 {
 333   int fd;
 334   int opt = 1;
 335
 336   if ((fd = socket(a->sa.sa_family, SOCK_STREAM, IPPROTO_TCP)) < 0 ||
 337       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) ||
 338       initsock(fd, a->sa.sa_family) ||
 339       bind(fd, &a->sa, addrsz(a)) ||
 340       listen(fd, 1) || nonblockify(fd) || cloexec(fd))
 341     die(1, "couldn't set up listening socket: %s", strerror(errno));
 342   sel_initfile(&sel, sf, fd, SEL_READ, doaccept, 0);
 343   sel_addfile(sf);
 344 }
 345
 346 static void dolisten(void)
 347 {
 348   size_t i, n;
 349
 350   n = DA_LEN(&cw.me);
 351   for (i = 0; i < n; i++)
 352     dolisten1(&DA(&cw.me)[i], &cw.sfv[i]);
 353 }
 354
 355 static void pushaddrs(addr_v *av, const struct addrinfo *ailist)
 356 {
 357   const struct addrinfo *ai;
 358   size_t i, n;
 359
 360   for (ai = ailist, n = 0; ai; ai = ai->ai_next)
 361     if (knownafp(ai->ai_family)) n++;
 362   DA_ENSURE(av, n);
 363   for (i = DA_LEN(av), ai = ailist; ai; ai = ai->ai_next) {
 364     if (!knownafp(ai->ai_family)) continue;
 365     initaddr(&DA(av)[i], ai->ai_family);
 366     copyaddr(&DA(av)[i++], ai->ai_addr, caf_addr | caf_port);
 367   }
 368   DA_EXTEND(av, n);
 369 }
 370
 371 #define paf_parse 1u
 372 static void parseaddr(const struct addrinfo *aihint,
 373                       const char *host, const char *svc, unsigned f,
 374                       struct addrinfo **ai_out)
 375 {
 376   char *alloc = 0, *sep;
 377   int err;
 378
 379   if (f&paf_parse) {
 380     alloc = xstrdup(host);
 381     if ((sep = strchr(alloc, ':')) == 0)
 382       die(1, "missing port number in address `%s'", host);
 383     host = alloc; *sep = 0; svc = sep + 1;
 384   }
 385
 386   err = getaddrinfo(host, svc, aihint, ai_out);
 387   if (err) {
 388     if (host && svc) {
 389       die(1, "failed to resolve hostname `%s', service `%s': %s",
 390           host, svc, gai_strerror(err));
 391     } else if (host)
 392       die(1, "failed to resolve hostname `%s': %s", host, gai_strerror(err));
 393     else
 394       die(1, "failed to resolve service `%s': %s", svc, gai_strerror(err));
 395   }
 396
 397   xfree(alloc);
 398 }
 399
 400 static void usage(FILE *fp)
 401 {
 402   pquis(fp,
 403         "Usage: $ [-l PORT] [-b ADDR] [-p ADDR] [-c ADDR:PORT]\n\
 404         ADDR:PORT ADDR:PORT\n");
 405 }
 406
 407 static void version(FILE *fp)
 408   { pquis(fp, "$, tripe version " VERSION "\n"); }
 409
 410 static void help(FILE *fp)
 411 {
 412   version(fp);
 413   fputc('\n', fp);
 414   usage(fp);
 415   fputs("\n\
 416 Options:\n\
 417 \n\
 418 -h, --help              Display this help text.\n\
 419 -v, --version           Display version number.\n\
 420 -u, --usage             Display pointless usage message.\n\
 421 \n\
 422 -l, --listen=PORT       Listen for connections to TCP PORT.\n\
 423 -p, --peer=ADDR         Only accept connections from IP ADDR.\n\
 424 -b, --bind=ADDR         Bind to ADDR before connecting.\n\
 425 -c, --connect=ADDR:PORT Connect to IP ADDR, TCP PORT.\n\
 426 \n\
 427 Forwards UDP packets over a reliable stream.  By default, uses stdin and\n\
 428 stdout; though it can use TCP sockets instead.\n\
 429 ", fp);
 430 }
 431
 432 int main(int argc, char *argv[])
 433 {
 434   unsigned f = 0;
 435   str_v bindhosts = DA_INIT, peerhosts = DA_INIT;
 436   const char *bindsvc = 0;
 437   addr bindaddr;
 438   const char *connhost = 0;
 439   struct addrinfo aihint = { 0 }, *ai, *ailist;
 440   int fd = -1;
 441   int len = 65536;
 442   size_t i, n;
 443
 444 #define f_bogus 1u
 445
 446   cw.f = 0;
 447
 448   ego(argv[0]);
 449   sel_init(&sel);
 450   for (;;) {
 451     static struct option opt[] = {
 452       { "help",                 0,              0,      'h' },
 453       { "version",              0,              0,      'v' },
 454       { "usage",                0,              0,      'u' },
 455       { "listen",               OPTF_ARGREQ,    0,      'l' },
 456       { "peer",                 OPTF_ARGREQ,    0,      'p' },
 457       { "bind",                 OPTF_ARGREQ,    0,      'b' },
 458       { "connect",              OPTF_ARGREQ,    0,      'c' },
 459       { 0,                      0,              0,      0 }
 460     };
 461     int i;
 462
 463     i = mdwopt(argc, argv, "hvul:p:b:c:", opt, 0, 0, 0);
 464     if (i < 0)
 465       break;
 466     switch (i) {
 467       case 'h': help(stdout); exit(0);
 468       case 'v': version(stdout); exit(0);
 469       case 'u': usage(stdout); exit(0);
 470       case 'l': bindsvc = optarg; break;
 471       case 'p': DA_PUSH(&peerhosts, optarg); break;
 472       case 'b': DA_PUSH(&bindhosts, optarg); break;
 473       case 'c': connhost = optarg; break;
 474       default: f |= f_bogus; break;
 475     }
 476   }
 477   if (optind + 2 != argc || (f&f_bogus)) { usage(stderr); exit(1); }
 478
 479   if (DA_LEN(&bindhosts) && !bindsvc && !connhost)
 480     die(1, "bind addr only makes sense when listening or connecting");
 481   if (DA_LEN(&peerhosts) && !bindsvc)
 482     die(1, "peer addr only makes sense when listening");
 483   if (bindsvc && connhost)
 484     die(1, "can't listen and connect");
 485
 486   aihint.ai_family = AF_INET;
 487   DA_CREATE(&cw.me); DA_CREATE(&cw.peer);
 488
 489   n = DA_LEN(&bindhosts);
 490   if (n || bindsvc) {
 491     aihint.ai_socktype = SOCK_STREAM;
 492     aihint.ai_protocol = IPPROTO_TCP;
 493     aihint.ai_flags = AI_ADDRCONFIG | AI_PASSIVE;
 494     if (!n) {
 495       parseaddr(&aihint, 0, bindsvc, 0, &ailist);
 496       pushaddrs(&cw.me, ailist);
 497       freeaddrinfo(ailist);
 498     } else if (!bindsvc) {
 499       if (n != 1) die(1, "can only bind to one address as client");
 500       parseaddr(&aihint, DA(&bindhosts)[0], 0, 0, &ailist);
 501       for (ai = ailist; ai && !knownafp(ai->ai_family); ai = ai->ai_next);
 502       if (!ai)
 503         die(1, "no usable addresses returned for `%s'", DA(&bindhosts)[0]);
 504       initaddr(&bindaddr, ai->ai_family);
 505       copyaddr(&bindaddr, ai->ai_addr, caf_addr);
 506       aihint.ai_family = ai->ai_family;
 507       freeaddrinfo(ailist);
 508     } else for (i = 0; i < n; i++) {
 509       parseaddr(&aihint, DA(&bindhosts)[i], bindsvc, 0, &ailist);
 510       pushaddrs(&cw.me, ailist);
 511       freeaddrinfo(ailist);
 512     }
 513     if (bindsvc) {
 514       cw.f |= cwf_port;
 515       n = DA_LEN(&cw.me);
 516       cw.sfv = xmalloc(n*sizeof(*cw.sfv));
 517     }
 518   }
 519
 520   n = DA_LEN(&peerhosts);
 521   if (n) {
 522     aihint.ai_socktype = SOCK_STREAM;
 523     aihint.ai_protocol = IPPROTO_TCP;
 524     aihint.ai_flags = AI_ADDRCONFIG;
 525     for (i = 0; i < n; i++) {
 526       parseaddr(&aihint, DA(&peerhosts)[i], 0, 0, &ailist);
 527       pushaddrs(&cw.peer, ailist);
 528       freeaddrinfo(ailist);
 529     }
 530     if (!DA_LEN(&cw.peer)) die(1, "no usable peer addresses");
 531   }
 532
 533   if (connhost) {
 534     aihint.ai_socktype = SOCK_STREAM;
 535     aihint.ai_protocol = IPPROTO_TCP;
 536     aihint.ai_flags = AI_ADDRCONFIG;
 537     parseaddr(&aihint, connhost, 0, paf_parse, &ailist);
 538
 539     for (ai = ailist; ai; ai = ai->ai_next) {
 540       if ((fd = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
 541           !initsock(fd, ai->ai_family) &&
 542           (!DA_LEN(&bindhosts) ||
 543            !bind(fd, &bindaddr.sa, addrsz(&bindaddr))) &&
 544           !connect(fd, ai->ai_addr, ai->ai_addrlen))
 545         goto conn_tcp;
 546       if (fd >= 0) close(fd);
 547     }
 548     die(1, "couldn't connect to TCP server: %s", strerror(errno));
 549   conn_tcp:
 550     if (nonblockify(fd) || cloexec(fd))
 551       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 552   }
 553
 554   aihint.ai_family = AF_INET;
 555   aihint.ai_socktype = SOCK_DGRAM;
 556   aihint.ai_protocol = IPPROTO_UDP;
 557   aihint.ai_flags = AI_ADDRCONFIG | AI_PASSIVE;
 558   parseaddr(&aihint, argv[optind], 0, paf_parse, &ailist);
 559   for (ai = ailist; ai && !knownafp(ai->ai_family); ai = ai->ai_next);
 560   if (!ai) die(1, "no usable addresses returned for `%s'", argv[optind]);
 561   if ((fd_udp = socket(ai->ai_family, SOCK_DGRAM, IPPROTO_UDP)) < 0 ||
 562       initsock(fd_udp, ai->ai_family) ||
 563       nonblockify(fd_udp) || cloexec(fd_udp) ||
 564       setsockopt(fd_udp, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 565       setsockopt(fd_udp, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)) ||
 566       bind(fd_udp, ai->ai_addr, ai->ai_addrlen))
 567     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 568   freeaddrinfo(ailist);
 569   aihint.ai_family = ai->ai_family;
 570   aihint.ai_flags = AI_ADDRCONFIG;
 571   parseaddr(&aihint, argv[optind + 1], 0, paf_parse, &ailist);
 572   for (ai = ailist; ai; ai = ai->ai_next)
 573     if (!connect(fd_udp, ai->ai_addr, ai->ai_addrlen)) goto conn_udp;
 574   die(1, "couldn't set up UDP socket: %s", strerror(errno));
 575 conn_udp:
 576
 577   if (bindsvc) dolisten();
 578   else if (connhost) dofwd(fd, fd);
 579   else dofwd(STDIN_FILENO, STDOUT_FILENO);
 580
 581   for (;;) {
 582     if (sel_select(&sel) && errno != EINTR)
 583       die(1, "select failed: %s", strerror(errno));
 584   }
 585   return (0);
 586 }
 587
 588 /*----- That's all, folks -------------------------------------------------*/