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 void initaddr(addr *a)
 103 {
 104   a->sin.sin_family = AF_INET;
 105   a->sin.sin_addr.s_addr = INADDR_ANY;
 106   a->sin.sin_port = 0;
 107 }
 108
 109 static void dolisten(void);
 110
 111 static void doclose(pkstream *p)
 112 {
 113   pk *pk, *ppk;
 114   close(p->w.fd);
 115   close(p->p.reader.fd);
 116   selpk_destroy(&p->p);
 117   if (!(p->f&PKF_FULL)) sel_rmfile(&p->r);
 118   if (p->npk) sel_rmfile(&p->w);
 119   for (pk = p->pks; pk; pk = ppk) {
 120     ppk = pk->next;
 121     xfree(pk->p);
 122     xfree(pk);
 123   }
 124   xfree(p);
 125   if (cw.f&cwf_port) dolisten();
 126   else exit(0);
 127 }
 128
 129 static void rdtcp(octet *b, size_t sz, pkbuf *pk, size_t *k, void *vp)
 130 {
 131   pkstream *p = vp;
 132   size_t pksz;
 133
 134   if (!sz) { doclose(p); return; }
 135   pksz = LOAD16(b);
 136   if (pksz + 2 == sz) {
 137     DISCARD(write(fd_udp, b + 2, pksz));
 138     selpk_want(&p->p, 2);
 139   } else {
 140     selpk_want(&p->p, pksz + 2);
 141     *k = sz;
 142   }
 143 }
 144
 145 static void wrtcp(int fd, unsigned mode, void *vp)
 146 {
 147 #define NPK 16
 148   struct iovec iov[NPK];
 149   pkstream *p = vp;
 150   size_t i;
 151   ssize_t n;
 152   pk *pk, *ppk;
 153
 154   for (i = 0, pk = p->pks; i < NPK && pk; i++, pk = pk->next) {
 155     iov[i].iov_base = pk->o;
 156     iov[i].iov_len = pk->n;
 157   }
 158
 159   if ((n = writev(fd, iov, i)) < 0) {
 160     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 161     moan("couldn't write to TCP socket: %s", strerror(errno));
 162     doclose(p);
 163     return;
 164   }
 165
 166   p->szpk -= n;
 167   for (pk = p->pks; n && pk; pk = ppk) {
 168     ppk = pk->next;
 169     if (pk->n <= n) {
 170       p->npk--;
 171       n -= pk->n;
 172       xfree(pk->p);
 173       xfree(pk);
 174     } else {
 175       pk->n -= n;
 176       pk->o += n;
 177       break;
 178     }
 179   }
 180   p->pks = pk;
 181   if (!pk) { p->pk_tail = &p->pks; sel_rmfile(&p->w); }
 182   if ((p->f&PKF_FULL) && p->npk < pk_nmax && p->szpk < pk_szmax)
 183     { p->f &= ~PKF_FULL; sel_addfile(&p->r); }
 184 }
 185
 186 static void rdudp(int fd, unsigned mode, void *vp)
 187 {
 188   octet buf[65536];
 189   ssize_t n;
 190   pkstream *p = vp;
 191   pk *pk;
 192
 193   if ((n = read(fd, buf, sizeof(buf))) < 0) {
 194     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
 195       return;
 196     moan("couldn't read from UDP socket: %s", strerror(errno));
 197     return;
 198   }
 199   pk = xmalloc(sizeof(*pk));
 200   pk->next = 0;
 201   pk->p = xmalloc(n + 2);
 202   STORE16(pk->p, n);
 203   memcpy(pk->p + 2, buf, n);
 204   pk->o = pk->p;
 205   pk->n = n + 2;
 206   *p->pk_tail = pk;
 207   p->pk_tail = &pk->next;
 208   if (!p->npk) sel_addfile(&p->w);
 209   sel_force(&p->w);
 210   p->npk++;
 211   p->szpk += n + 2;
 212   if (p->npk >= pk_nmax || p->szpk >= pk_szmax)
 213     { sel_rmfile(&p->r); p->f |= PKF_FULL; }
 214 }
 215
 216 static void dofwd(int fd_in, int fd_out)
 217 {
 218   pkstream *p = xmalloc(sizeof(*p));
 219   sel_initfile(&sel, &p->r, fd_udp, SEL_READ, rdudp, p);
 220   sel_initfile(&sel, &p->w, fd_out, SEL_WRITE, wrtcp, p);
 221   selpk_init(&p->p, &sel, fd_in, rdtcp, p);
 222   selpk_want(&p->p, 2);
 223   p->pks = 0;
 224   p->pk_tail = &p->pks;
 225   p->npk = p->szpk = 0;
 226   p->f = 0;
 227   sel_addfile(&p->r);
 228 }
 229
 230 static void doaccept(int fd_s, unsigned mode, void *p)
 231 {
 232   int fd;
 233   addr a;
 234   socklen_t sz = sizeof(a);
 235
 236   if ((fd = accept(fd_s, &a.sa, &sz)) < 0) {
 237     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 238     moan("couldn't accept incoming connection: %s", strerror(errno));
 239     return;
 240   }
 241   if (cw.peer.sin.sin_addr.s_addr != INADDR_ANY &&
 242       cw.peer.sin.sin_addr.s_addr != a.sin.sin_addr.s_addr) {
 243     moan("rejecting connection from %s", inet_ntoa(a.sin.sin_addr));
 244     close(fd); return;
 245   }
 246   if (nonblockify(fd) || cloexec(fd)) {
 247     moan("couldn't accept incoming connection: %s", strerror(errno));
 248     close(fd); return;
 249   }
 250   dofwd(fd, fd);
 251   close(fd_s);
 252   sel_rmfile(&cw.a);
 253 }
 254
 255 static void dolisten(void)
 256 {
 257   int fd;
 258   int opt = 1;
 259
 260   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0 ||
 261       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) ||
 262       bind(fd, &cw.me.sa, sizeof(cw.me.sin)) ||
 263       listen(fd, 1) || nonblockify(fd) || cloexec(fd))
 264     die(1, "couldn't set up listening socket: %s", strerror(errno));
 265   sel_initfile(&sel, &cw.a, fd, SEL_READ, doaccept, 0);
 266   sel_addfile(&cw.a);
 267 }
 268
 269 #define paf_parse 1u
 270 static void parseaddr(const char *host, const char *svc, unsigned f, addr *a)
 271 {
 272   char *alloc = 0, *sep;
 273   struct hostent *h;
 274   struct servent *s;
 275   char *qq;
 276   unsigned long n;
 277
 278   if (f&paf_parse) {
 279     alloc = xstrdup(host);
 280     if ((sep = strchr(alloc, ':')) == 0)
 281       die(1, "missing port number in address `%s'", host);
 282     host = alloc; *sep = 0; svc = sep + 1;
 283   }
 284
 285   if (host) {
 286     if ((h = gethostbyname(host)) == 0) die(1, "unknown host `%s'", host);
 287     memcpy(&a->sin.sin_addr, h->h_addr, sizeof(a->sin.sin_addr));
 288   }
 289
 290   if (svc) {
 291     if ((n = strtoul(svc, &qq, 0)) > 0 && !*qq && n <= 0xffff)
 292       a->sin.sin_port = htons(n);
 293     else if ((s = getservbyname(svc, "tcp")) != 0)
 294       a->sin.sin_port = s->s_port;
 295     else
 296       die(1, "bad service name/number `%s'", svc);
 297   }
 298
 299   xfree(alloc);
 300 }
 301
 302 static void usage(FILE *fp)
 303 {
 304   pquis(fp,
 305         "Usage: $ [-l PORT] [-b ADDR] [-p ADDR] [-c ADDR:PORT]\n\
 306         ADDR:PORT ADDR:PORT\n");
 307 }
 308
 309 static void version(FILE *fp)
 310   { pquis(fp, "$, tripe version " VERSION "\n"); }
 311
 312 static void help(FILE *fp)
 313 {
 314   version(fp);
 315   fputc('\n', fp);
 316   usage(fp);
 317   fputs("\n\
 318 Options:\n\
 319 \n\
 320 -h, --help              Display this help text.\n\
 321 -v, --version           Display version number.\n\
 322 -u, --usage             Display pointless usage message.\n\
 323 \n\
 324 -l, --listen=PORT       Listen for connections to TCP PORT.\n\
 325 -p, --peer=ADDR         Only accept connections from IP ADDR.\n\
 326 -b, --bind=ADDR         Bind to ADDR before connecting.\n\
 327 -c, --connect=ADDR:PORT Connect to IP ADDR, TCP PORT.\n\
 328 \n\
 329 Forwards UDP packets over a reliable stream.  By default, uses stdin and\n\
 330 stdout; though it can use TCP sockets instead.\n\
 331 ", fp);
 332 }
 333
 334 int main(int argc, char *argv[])
 335 {
 336   unsigned f = 0;
 337   const char *bindhost = 0, *bindsvc = 0, *peerhost = 0;
 338   addr bindaddr;
 339   const char *connhost = 0;
 340   addr tmpaddr;
 341   int fd = -1;
 342   int len = 65536;
 343
 344 #define f_bogus 1u
 345
 346   cw.f = 0;
 347
 348   ego(argv[0]);
 349   sel_init(&sel);
 350   for (;;) {
 351     static struct option opt[] = {
 352       { "help",                 0,              0,      'h' },
 353       { "version",              0,              0,      'v' },
 354       { "usage",                0,              0,      'u' },
 355       { "listen",               OPTF_ARGREQ,    0,      'l' },
 356       { "peer",                 OPTF_ARGREQ,    0,      'p' },
 357       { "bind",                 OPTF_ARGREQ,    0,      'b' },
 358       { "connect",              OPTF_ARGREQ,    0,      'c' },
 359       { 0,                      0,              0,      0 }
 360     };
 361     int i;
 362
 363     i = mdwopt(argc, argv, "hvul:p:b:c:", opt, 0, 0, 0);
 364     if (i < 0)
 365       break;
 366     switch (i) {
 367       case 'h': help(stdout); exit(0);
 368       case 'v': version(stdout); exit(0);
 369       case 'u': usage(stdout); exit(0);
 370       case 'l': bindsvc = optarg; break;
 371       case 'p': peerhost = optarg; break;
 372       case 'b': bindhost = optarg; break;
 373       case 'c': connhost = optarg; break;
 374       default: f |= f_bogus; break;
 375     }
 376   }
 377   if (optind + 2 != argc || (f&f_bogus)) { usage(stderr); exit(1); }
 378
 379   if (bindhost && !bindsvc && !connhost)
 380     die(1, "bind addr only makes sense when listening or connecting");
 381   if (peerhost && !bindsvc)
 382     die(1, "peer addr only makes sense when listening");
 383   if (bindsvc && connhost)
 384     die(1, "can't listen and connect");
 385
 386   if (bindhost || bindsvc) {
 387     initaddr(&bindaddr);
 388     if (!bindsvc) parseaddr(bindhost, 0, 0, &bindaddr);
 389     else {
 390       initaddr(&cw.me);
 391       parseaddr(bindhost, bindsvc, 0, &cw.me);
 392       cw.f |= cwf_port;
 393     }
 394   }
 395
 396   initaddr(&cw.peer);
 397   if (peerhost) parseaddr(peerhost, 0, 0, &cw.peer);
 398
 399   if (connhost) {
 400     initaddr(&tmpaddr);
 401     parseaddr(connhost, 0, paf_parse, &tmpaddr);
 402     if ((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0 ||
 403         (bindhost &&
 404          bind(fd, &bindaddr.sa, sizeof(bindaddr.sin))) ||
 405         connect(fd, &tmpaddr.sa, sizeof(tmpaddr.sin)))
 406       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 407     if (nonblockify(fd) || cloexec(fd))
 408       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 409   }
 410
 411   initaddr(&tmpaddr);
 412   parseaddr(argv[optind], 0, paf_parse, &tmpaddr);
 413   if ((fd_udp = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0 ||
 414       nonblockify(fd_udp) || cloexec(fd_udp) ||
 415       setsockopt(fd_udp, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 416       setsockopt(fd_udp, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)) ||
 417       bind(fd_udp, &tmpaddr.sa, sizeof(tmpaddr.sin)))
 418     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 419   initaddr(&tmpaddr);
 420   parseaddr(argv[optind + 1], 0, paf_parse, &tmpaddr);
 421   if (connect(fd_udp, &tmpaddr.sa, sizeof(tmpaddr.sin)))
 422     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 423
 424   if (bindsvc) dolisten();
 425   else if (connhost) dofwd(fd, fd);
 426   else dofwd(STDIN_FILENO, STDOUT_FILENO);
 427
 428   for (;;) {
 429     if (sel_select(&sel) && errno != EINTR)
 430       die(1, "select failed: %s", strerror(errno));
 431   }
 432   return (0);
 433 }
 434
 435 /*----- That's all, folks -------------------------------------------------*/