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