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 struct pk {
  61   struct pk *next;                      /* Next packet in the chain */
  62   octet *p, *o;                         /* Buffer start and current posn */
  63   size_t n;                             /* Size of packet remaining */
  64 } pk;
  65
  66 typedef struct pkstream {
  67   unsigned f;                           /* Flags... */
  68 #define PKF_FULL 1u                     /*   Buffer is full: stop reading */
  69   sel_file r, w;                        /* Read and write selectors */
  70   pk *pks, **pk_tail;                   /* Packet queue */
  71   size_t npk, szpk;                     /* Number and size of data */
  72   selpk p;                              /* Packet parser */
  73 } pkstream;
  74
  75 typedef struct connwait {
  76   unsigned f;                           /* Various flags */
  77 #define cwf_port 1u                     /*   Port is defined => listen */
  78   sel_file a;                           /* Selector */
  79   struct sockaddr_in me, peer;         /* Who I'm meant to be; who peer is */
  80 } connwait;
  81
  82 /*----- Static variables --------------------------------------------------*/
  83
  84 static sel_state sel;
  85 static connwait cw;
  86 static int fd_udp;
  87 static size_t pk_nmax = 128, pk_szmax = 1024*1024;
  88
  89 /*----- Main code ---------------------------------------------------------*/
  90
  91 static int nonblockify(int fd)
  92   { return (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)); }
  93
  94 static int cloexec(int fd)
  95   { return (fdflags(fd, 0, 0, FD_CLOEXEC, FD_CLOEXEC)); }
  96
  97 static void initaddr(struct sockaddr_in *sin)
  98 {
  99   sin->sin_family = AF_INET;
 100   sin->sin_addr.s_addr = INADDR_ANY;
 101   sin->sin_port = 0;
 102 }
 103
 104 static void dolisten(void);
 105
 106 static void doclose(pkstream *p)
 107 {
 108   pk *pk, *ppk;
 109   close(p->w.fd);
 110   close(p->p.reader.fd);
 111   selpk_destroy(&p->p);
 112   if (!(p->f&PKF_FULL)) sel_rmfile(&p->r);
 113   if (p->npk) sel_rmfile(&p->w);
 114   for (pk = p->pks; pk; pk = ppk) {
 115     ppk = pk->next;
 116     xfree(pk->p);
 117     xfree(pk);
 118   }
 119   xfree(p);
 120   if (cw.f&cwf_port) dolisten();
 121   else exit(0);
 122 }
 123
 124 static void rdtcp(octet *b, size_t sz, pkbuf *pk, size_t *k, void *vp)
 125 {
 126   pkstream *p = vp;
 127   size_t pksz;
 128
 129   if (!sz) { doclose(p); return; }
 130   pksz = LOAD16(b);
 131   if (pksz + 2 == sz) {
 132     DISCARD(write(fd_udp, b + 2, pksz));
 133     selpk_want(&p->p, 2);
 134   } else {
 135     selpk_want(&p->p, pksz + 2);
 136     *k = sz;
 137   }
 138 }
 139
 140 static void wrtcp(int fd, unsigned mode, void *vp)
 141 {
 142 #define NPK 16
 143   struct iovec iov[NPK];
 144   pkstream *p = vp;
 145   size_t i;
 146   ssize_t n;
 147   pk *pk, *ppk;
 148
 149   for (i = 0, pk = p->pks; i < NPK && pk; i++, pk = pk->next) {
 150     iov[i].iov_base = pk->o;
 151     iov[i].iov_len = pk->n;
 152   }
 153
 154   if ((n = writev(fd, iov, i)) < 0) {
 155     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 156     moan("couldn't write to TCP socket: %s", strerror(errno));
 157     doclose(p);
 158     return;
 159   }
 160
 161   p->szpk -= n;
 162   for (pk = p->pks; n && pk; pk = ppk) {
 163     ppk = pk->next;
 164     if (pk->n <= n) {
 165       p->npk--;
 166       n -= pk->n;
 167       xfree(pk->p);
 168       xfree(pk);
 169     } else {
 170       pk->n -= n;
 171       pk->o += n;
 172       break;
 173     }
 174   }
 175   p->pks = pk;
 176   if (!pk) { p->pk_tail = &p->pks; sel_rmfile(&p->w); }
 177   if ((p->f&PKF_FULL) && p->npk < pk_nmax && p->szpk < pk_szmax)
 178     { p->f &= ~PKF_FULL; sel_addfile(&p->r); }
 179 }
 180
 181 static void rdudp(int fd, unsigned mode, void *vp)
 182 {
 183   octet buf[65536];
 184   ssize_t n;
 185   pkstream *p = vp;
 186   pk *pk;
 187
 188   if ((n = read(fd, buf, sizeof(buf))) < 0) {
 189     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
 190       return;
 191     moan("couldn't read from UDP socket: %s", strerror(errno));
 192     return;
 193   }
 194   pk = xmalloc(sizeof(*pk));
 195   pk->next = 0;
 196   pk->p = xmalloc(n + 2);
 197   STORE16(pk->p, n);
 198   memcpy(pk->p + 2, buf, n);
 199   pk->o = pk->p;
 200   pk->n = n + 2;
 201   *p->pk_tail = pk;
 202   p->pk_tail = &pk->next;
 203   if (!p->npk) sel_addfile(&p->w);
 204   sel_force(&p->w);
 205   p->npk++;
 206   p->szpk += n + 2;
 207   if (p->npk >= pk_nmax || p->szpk >= pk_szmax)
 208     { sel_rmfile(&p->r); p->f |= PKF_FULL; }
 209 }
 210
 211 static void dofwd(int fd_in, int fd_out)
 212 {
 213   pkstream *p = xmalloc(sizeof(*p));
 214   sel_initfile(&sel, &p->r, fd_udp, SEL_READ, rdudp, p);
 215   sel_initfile(&sel, &p->w, fd_out, SEL_WRITE, wrtcp, p);
 216   selpk_init(&p->p, &sel, fd_in, rdtcp, p);
 217   selpk_want(&p->p, 2);
 218   p->pks = 0;
 219   p->pk_tail = &p->pks;
 220   p->npk = p->szpk = 0;
 221   p->f = 0;
 222   sel_addfile(&p->r);
 223 }
 224
 225 static void doaccept(int fd_s, unsigned mode, void *p)
 226 {
 227   int fd;
 228   struct sockaddr_in sin;
 229   socklen_t sz = sizeof(sin);
 230
 231   if ((fd = accept(fd_s, (struct sockaddr *)&sin, &sz)) < 0) {
 232     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 233     moan("couldn't accept incoming connection: %s", strerror(errno));
 234     return;
 235   }
 236   if (cw.peer.sin_addr.s_addr != INADDR_ANY &&
 237       cw.peer.sin_addr.s_addr != sin.sin_addr.s_addr) {
 238     moan("rejecting connection from %s", inet_ntoa(sin.sin_addr));
 239     close(fd); return;
 240   }
 241   if (nonblockify(fd) || cloexec(fd)) {
 242     moan("couldn't accept incoming connection: %s", strerror(errno));
 243     close(fd); return;
 244   }
 245   dofwd(fd, fd);
 246   close(fd_s);
 247   sel_rmfile(&cw.a);
 248 }
 249
 250 static void dolisten(void)
 251 {
 252   int fd;
 253   int opt = 1;
 254
 255   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0 ||
 256       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) ||
 257       bind(fd, (struct sockaddr *)&cw.me, sizeof(cw.me)) ||
 258       listen(fd, 1) || nonblockify(fd) || cloexec(fd))
 259     die(1, "couldn't set up listening socket: %s", strerror(errno));
 260   sel_initfile(&sel, &cw.a, fd, SEL_READ, doaccept, 0);
 261   sel_addfile(&cw.a);
 262 }
 263
 264 #define paf_parse 1u
 265 static void parseaddr(const char *host, const char *svc, unsigned f,
 266                       struct sockaddr_in *sin)
 267 {
 268   char *alloc = 0, *sep;
 269   struct hostent *h;
 270   struct servent *s;
 271   char *qq;
 272   unsigned long n;
 273
 274   if (f&paf_parse) {
 275     alloc = xstrdup(host);
 276     if ((sep = strchr(alloc, ':')) == 0)
 277       die(1, "missing port number in address `%s'", host);
 278     host = alloc; *sep = 0; svc = sep + 1;
 279   }
 280
 281   if (host) {
 282     if ((h = gethostbyname(host)) == 0) die(1, "unknown host `%s'", host);
 283     memcpy(&sin->sin_addr, h->h_addr, sizeof(sin->sin_addr));
 284   }
 285
 286   if (svc) {
 287     if ((n = strtoul(svc, &qq, 0)) > 0 && !*qq && n <= 0xffff)
 288       sin->sin_port = htons(n);
 289     else if ((s = getservbyname(svc, "tcp")) != 0)
 290       sin->sin_port = s->s_port;
 291     else
 292       die(1, "bad service name/number `%s'", svc);
 293   }
 294
 295   xfree(alloc);
 296 }
 297
 298 static void usage(FILE *fp)
 299 {
 300   pquis(fp,
 301         "Usage: $ [-l PORT] [-b ADDR] [-p ADDR] [-c ADDR:PORT]\n\
 302         ADDR:PORT ADDR:PORT\n");
 303 }
 304
 305 static void version(FILE *fp)
 306   { pquis(fp, "$, tripe version " VERSION "\n"); }
 307
 308 static void help(FILE *fp)
 309 {
 310   version(fp);
 311   fputc('\n', fp);
 312   usage(fp);
 313   fputs("\n\
 314 Options:\n\
 315 \n\
 316 -h, --help              Display this help text.\n\
 317 -v, --version           Display version number.\n\
 318 -u, --usage             Display pointless usage message.\n\
 319 \n\
 320 -l, --listen=PORT       Listen for connections to TCP PORT.\n\
 321 -p, --peer=ADDR         Only accept connections from IP ADDR.\n\
 322 -b, --bind=ADDR         Bind to ADDR before connecting.\n\
 323 -c, --connect=ADDR:PORT Connect to IP ADDR, TCP PORT.\n\
 324 \n\
 325 Forwards UDP packets over a reliable stream.  By default, uses stdin and\n\
 326 stdout; though it can use TCP sockets instead.\n\
 327 ", fp);
 328 }
 329
 330 int main(int argc, char *argv[])
 331 {
 332   unsigned f = 0;
 333   const char *bindhost = 0, *bindsvc = 0, *peerhost = 0;
 334   struct sockaddr_in bindaddr;
 335   const char *connhost = 0;
 336   struct sockaddr_in tmpaddr;
 337   int fd = -1;
 338   int len = 65536;
 339
 340 #define f_bogus 1u
 341
 342   cw.f = 0;
 343
 344   ego(argv[0]);
 345   sel_init(&sel);
 346   for (;;) {
 347     static struct option opt[] = {
 348       { "help",                 0,              0,      'h' },
 349       { "version",              0,              0,      'v' },
 350       { "usage",                0,              0,      'u' },
 351       { "listen",               OPTF_ARGREQ,    0,      'l' },
 352       { "peer",                 OPTF_ARGREQ,    0,      'p' },
 353       { "bind",                 OPTF_ARGREQ,    0,      'b' },
 354       { "connect",              OPTF_ARGREQ,    0,      'c' },
 355       { 0,                      0,              0,      0 }
 356     };
 357     int i;
 358
 359     i = mdwopt(argc, argv, "hvul:p:b:c:", opt, 0, 0, 0);
 360     if (i < 0)
 361       break;
 362     switch (i) {
 363       case 'h': help(stdout); exit(0);
 364       case 'v': version(stdout); exit(0);
 365       case 'u': usage(stdout); exit(0);
 366       case 'l': bindsvc = optarg; break;
 367       case 'p': peerhost = optarg; break;
 368       case 'b': bindhost = optarg; break;
 369       case 'c': connhost = optarg; break;
 370       default: f |= f_bogus; break;
 371     }
 372   }
 373   if (optind + 2 != argc || (f&f_bogus)) { usage(stderr); exit(1); }
 374
 375   if (bindhost && !bindsvc && !connhost)
 376     die(1, "bind addr only makes sense when listening or connecting");
 377   if (peerhost && !bindsvc)
 378     die(1, "peer addr only makes sense when listening");
 379   if (bindsvc && connhost)
 380     die(1, "can't listen and connect");
 381
 382   if (bindhost || bindsvc) {
 383     initaddr(&bindaddr);
 384     if (!bindsvc) parseaddr(bindhost, 0, 0, &bindaddr);
 385     else {
 386       initaddr(&cw.me);
 387       parseaddr(bindhost, bindsvc, 0, &cw.me);
 388       cw.f |= cwf_port;
 389     }
 390   }
 391
 392   initaddr(&cw.peer);
 393   if (peerhost) parseaddr(peerhost, 0, 0, &cw.peer);
 394
 395   if (connhost) {
 396     initaddr(&tmpaddr);
 397     parseaddr(connhost, 0, paf_parse, &tmpaddr);
 398     if ((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0 ||
 399         (bindhost &&
 400          bind(fd, (struct sockaddr *)&bindaddr, sizeof(bindaddr))) ||
 401         connect(fd, (struct sockaddr *)&tmpaddr, sizeof(tmpaddr)))
 402       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 403     if (nonblockify(fd) || cloexec(fd))
 404       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 405   }
 406
 407   initaddr(&tmpaddr);
 408   parseaddr(argv[optind], 0, paf_parse, &tmpaddr);
 409   if ((fd_udp = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0 ||
 410       nonblockify(fd_udp) || cloexec(fd_udp) ||
 411       setsockopt(fd_udp, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 412       setsockopt(fd_udp, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)) ||
 413       bind(fd_udp, (struct sockaddr *)&tmpaddr, sizeof(tmpaddr)))
 414     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 415   initaddr(&tmpaddr);
 416   parseaddr(argv[optind + 1], 0, paf_parse, &tmpaddr);
 417   if (connect(fd_udp, (struct sockaddr *)&tmpaddr, sizeof(tmpaddr)))
 418     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 419
 420   if (bindsvc) dolisten();
 421   else if (connhost) dofwd(fd, fd);
 422   else dofwd(STDIN_FILENO, STDOUT_FILENO);
 423
 424   for (;;) {
 425     if (sel_select(&sel) && errno != EINTR)
 426       die(1, "select failed: %s", strerror(errno));
 427   }
 428   return (0);
 429 }
 430
 431 /*----- That's all, folks -------------------------------------------------*/