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