socket.c

   1 /* -*- c-file-style: "linux" -*-
   2
   3    rsync -- fast file replication program
   4
   5    Copyright (C) 1992-2001 by Andrew Tridgell <tridge@samba.org>
   6    Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org>
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 /**
  24  * @file socket.c
  25  *
  26  * Socket functions used in rsync.
  27  *
  28  * This file is now converted to use the new-style getaddrinfo()
  29  * interface, which supports IPv6 but is also supported on recent
  30  * IPv4-only machines.  On systems that don't have that interface, we
  31  * emulate it using the KAME implementation.
  32  **/
  33
  34 #include "rsync.h"
  35
  36
  37 /**
  38  * Establish a proxy connection on an open socket to a web proxy by
  39  * using the HTTP CONNECT method.
  40  **/
  41 static int establish_proxy_connection(int fd, char *host, int port)
  42 {
  43         char buffer[1024];
  44         char *cp;
  45
  46         snprintf(buffer, sizeof(buffer), "CONNECT %s:%d HTTP/1.0\r\n\r\n", host, port);
  47         if (write(fd, buffer, strlen(buffer)) != (int) strlen(buffer)) {
  48                 rprintf(FERROR, "failed to write to proxy: %s\n",
  49                         strerror(errno));
  50                 return -1;
  51         }
  52
  53         for (cp = buffer; cp < &buffer[sizeof(buffer) - 1]; cp++) {
  54                 if (read(fd, cp, 1) != 1) {
  55                         rprintf(FERROR, "failed to read from proxy: %s\n",
  56                                 strerror(errno));
  57                         return -1;
  58                 }
  59                 if (*cp == '\n')
  60                         break;
  61         }
  62
  63         if (*cp != '\n')
  64                 cp++;
  65         *cp-- = '\0';
  66         if (*cp == '\r')
  67                 *cp = '\0';
  68         if (strncmp(buffer, "HTTP/", 5) != 0) {
  69                 rprintf(FERROR, "bad response from proxy - %s\n",
  70                         buffer);
  71                 return -1;
  72         }
  73         for (cp = &buffer[5]; isdigit(* (unsigned char *) cp) || (*cp == '.'); cp++)
  74                 ;
  75         while (*cp == ' ')
  76                 cp++;
  77         if (*cp != '2') {
  78                 rprintf(FERROR, "bad response from proxy - %s\n",
  79                         buffer);
  80                 return -1;
  81         }
  82         /* throw away the rest of the HTTP header */
  83         while (1) {
  84                 for (cp = buffer; cp < &buffer[sizeof(buffer) - 1];
  85                      cp++) {
  86                         if (read(fd, cp, 1) != 1) {
  87                                 rprintf(FERROR, "failed to read from proxy: %s\n",
  88                                         strerror(errno));
  89                                 return -1;
  90                         }
  91                         if (*cp == '\n')
  92                                 break;
  93                 }
  94                 if ((cp > buffer) && (*cp == '\n'))
  95                         cp--;
  96                 if ((cp == buffer) && ((*cp == '\n') || (*cp == '\r')))
  97                         break;
  98         }
  99         return 0;
 100 }
 101
 102
 103 /**
 104  * Try to set the local address for a newly-created socket.  Return -1
 105  * if this fails.
 106  **/
 107 int try_bind_local(int s,
 108                    int ai_family, int ai_socktype,
 109                    const char *bind_address)
 110 {
 111         int error;
 112         struct addrinfo bhints, *bres_all, *r;
 113
 114         memset(&bhints, 0, sizeof(bhints));
 115         bhints.ai_family = ai_family;
 116         bhints.ai_socktype = ai_socktype;
 117         bhints.ai_flags = AI_PASSIVE;
 118         if ((error = getaddrinfo(bind_address, NULL, &bhints, &bres_all))) {
 119                 rprintf(FERROR, RSYNC_NAME ": getaddrinfo %s: %s\n",
 120                         bind_address, gai_strerror(error));
 121                 return -1;
 122         }
 123
 124         for (r = bres_all; r; r = r->ai_next) {
 125                 if (bind(s, r->ai_addr, r->ai_addrlen) == -1)
 126                         continue;
 127                 freeaddrinfo(bres_all);
 128                 return s;
 129         }
 130
 131         /* no error message; there might be some problem that allows
 132          * creation of the socket but not binding, perhaps if the
 133          * machine has no ipv6 address of this name. */
 134         freeaddrinfo(bres_all);
 135         return -1;
 136 }
 137
 138
 139 /**
 140  * Open a socket to a tcp remote host with the specified port .
 141  *
 142  * Based on code from Warren.  Proxy support by Stephen Rothwell.
 143  * getaddrinfo() rewrite contributed by KAME.net.
 144  *
 145  * Now that we support IPv6 we need to look up the remote machine's
 146  * address first, using @p af_hint to set a preference for the type
 147  * of address.  Then depending on whether it has v4 or v6 addresses we
 148  * try to open a connection.
 149  *
 150  * The loop allows for machines with some addresses which may not be
 151  * reachable, perhaps because we can't e.g. route ipv6 to that network
 152  * but we can get ip4 packets through.
 153  *
 154  * @param bind_address Local address to use.  Normally NULL to bind
 155  * the wildcard address.
 156  *
 157  * @param af_hint Address family, e.g. AF_INET or AF_INET6.
 158  **/
 159 int open_socket_out(char *host, int port, const char *bind_address,
 160                     int af_hint)
 161 {
 162         int type = SOCK_STREAM;
 163         int error;
 164         int s;
 165         struct addrinfo hints, *res0, *res;
 166         char portbuf[10];
 167         char *h;
 168         int proxied = 0;
 169         char buffer[1024];
 170         char *cp;
 171
 172         /* if we have a RSYNC_PROXY env variable then redirect our
 173          * connetcion via a web proxy at the given address. The format
 174          * is hostname:port */
 175         h = getenv("RSYNC_PROXY");
 176         proxied = (h != NULL) && (*h != '\0');
 177
 178         if (proxied) {
 179                 strlcpy(buffer, h, sizeof(buffer));
 180                 cp = strchr(buffer, ':');
 181                 if (cp == NULL) {
 182                         rprintf(FERROR,
 183                                 "invalid proxy specification: should be HOST:PORT\n");
 184                         return -1;
 185                 }
 186                 *cp++ = '\0';
 187                 strcpy(portbuf, cp);
 188                 h = buffer;
 189                 if (verbose >= 2) {
 190                         rprintf(FINFO, "connection via http proxy %s port %s\n",
 191                                 h, portbuf);
 192                 }
 193         } else {
 194                 snprintf(portbuf, sizeof(portbuf), "%d", port);
 195                 h = host;
 196         }
 197
 198         memset(&hints, 0, sizeof(hints));
 199         hints.ai_family = af_hint;
 200         hints.ai_socktype = type;
 201         error = getaddrinfo(h, portbuf, &hints, &res0);
 202         if (error) {
 203                 rprintf(FERROR, RSYNC_NAME ": getaddrinfo: %s %s: %s\n",
 204                         h, portbuf, gai_strerror(error));
 205                 return -1;
 206         }
 207
 208         s = -1;
 209         /* Try to connect to all addresses for this machine until we get
 210          * through.  It might e.g. be multi-homed, or have both IPv4 and IPv6
 211          * addresses.  We need to create a socket for each record, since the
 212          * address record tells us what protocol to use to try to connect. */
 213         for (res = res0; res; res = res->ai_next) {
 214                 s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
 215                 if (s < 0)
 216                         continue;
 217
 218                 if (bind_address)
 219                         if (try_bind_local(s, res->ai_family, type,
 220                                            bind_address) == -1) {
 221                                 close(s);
 222                                 s = -1;
 223                                 continue;
 224                         }
 225
 226                 if (connect(s, res->ai_addr, res->ai_addrlen) < 0) {
 227                         close(s);
 228                         s = -1;
 229                         continue;
 230                 }
 231                 if (proxied &&
 232                     establish_proxy_connection(s, host, port) != 0) {
 233                         close(s);
 234                         s = -1;
 235                         continue;
 236                 } else
 237                         break;
 238         }
 239         freeaddrinfo(res0);
 240         if (s < 0) {
 241                 rprintf(FERROR, RSYNC_NAME ": failed to connect to %s: %s\n",
 242                         h, strerror(errno));
 243                 return -1;
 244         }
 245         return s;
 246 }
 247
 248
 249 /**
 250  * Open an outgoing socket, but allow for it to be intercepted by
 251  * $RSYNC_CONNECT_PROG, which will execute a program across a TCP
 252  * socketpair rather than really opening a socket.
 253  *
 254  * We use this primarily in testing to detect TCP flow bugs, but not
 255  * cause security problems by really opening remote connections.
 256  *
 257  * This is based on the Samba LIBSMB_PROG feature.
 258  *
 259  * @param bind_address Local address to use.  Normally NULL to get the stack default.
 260  **/
 261 int open_socket_out_wrapped (char *host,
 262                              int port,
 263                              const char *bind_address,
 264                              int af_hint)
 265 {
 266         char *prog;
 267
 268         if ((prog = getenv ("RSYNC_CONNECT_PROG")) != NULL)
 269                 return sock_exec (prog);
 270         else
 271                 return open_socket_out (host, port, bind_address,
 272                                         af_hint);
 273 }
 274
 275
 276
 277 /**
 278  * Open a socket of the specified type, port and address for incoming data
 279  *
 280  * Try to be better about handling the results of getaddrinfo(): when
 281  * opening an inbound socket, we might get several address results,
 282  * e.g. for the machine's ipv4 and ipv6 name.
 283  *
 284  * If binding a wildcard, then any one of them should do.  If an address
 285  * was specified but it's insufficiently specific then that's not our
 286  * fault.
 287  *
 288  * However, some of the advertized addresses may not work because e.g. we
 289  * don't have IPv6 support in the kernel.  In that case go on and try all
 290  * addresses until one succeeds.
 291  *
 292  * @param bind_address Local address to bind, or NULL to allow it to
 293  * default.
 294  **/
 295 static int open_socket_in(int type, int port, const char *bind_address,
 296                           int af_hint)
 297 {
 298         int one=1;
 299         int s;
 300         struct addrinfo hints, *all_ai, *resp;
 301         char portbuf[10];
 302         int error;
 303
 304         memset(&hints, 0, sizeof(hints));
 305         hints.ai_family = af_hint;
 306         hints.ai_socktype = type;
 307         hints.ai_flags = AI_PASSIVE;
 308         snprintf(portbuf, sizeof(portbuf), "%d", port);
 309         error = getaddrinfo(bind_address, portbuf, &hints, &all_ai);
 310         if (error) {
 311                 rprintf(FERROR, RSYNC_NAME ": getaddrinfo: bind address %s: %s\n",
 312                         bind_address, gai_strerror(error));
 313                 return -1;
 314         }
 315
 316         /* We may not be able to create the socket, if for example the
 317          * machine knows about IPv6 in the C library, but not in the
 318          * kernel. */
 319         for (resp = all_ai; resp; resp = resp->ai_next) {
 320                 s = socket(resp->ai_family, resp->ai_socktype,
 321                            resp->ai_protocol);
 322
 323                 if (s == -1)
 324                         /* See if there's another address that will work... */
 325                         continue;
 326
 327                 setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
 328                            (char *)&one, sizeof one);
 329
 330                 /* now we've got a socket - we need to bind it */
 331                 if (bind(s, all_ai->ai_addr, all_ai->ai_addrlen) < 0) {
 332                         /* Nope, try another */
 333                         close(s);
 334                         continue;
 335                 }
 336
 337                 freeaddrinfo(all_ai);
 338                 return s;
 339         }
 340
 341         rprintf(FERROR, RSYNC_NAME ": open inbound socket on port %d failed: "
 342                 "%s\n",
 343                 port,
 344                 strerror(errno));
 345
 346         freeaddrinfo(all_ai);
 347         return -1;
 348 }
 349
 350
 351 /*
 352  * Determine if a file descriptor is in fact a socket
 353  */
 354 int is_a_socket(int fd)
 355 {
 356         int v;
 357         socklen_t l;
 358         l = sizeof(int);
 359
 360         /* Parameters to getsockopt, setsockopt etc are very
 361          * unstandardized across platforms, so don't be surprised if
 362          * there are compiler warnings on e.g. SCO OpenSwerver or AIX.
 363          * It seems they all eventually get the right idea.
 364          *
 365          * Debian says: ``The fifth argument of getsockopt and
 366          * setsockopt is in reality an int [*] (and this is what BSD
 367          * 4.* and libc4 and libc5 have).  Some POSIX confusion
 368          * resulted in the present socklen_t.  The draft standard has
 369          * not been adopted yet, but glibc2 already follows it and
 370          * also has socklen_t [*]. See also accept(2).''
 371          *
 372          * We now return to your regularly scheduled programming.  */
 373         return(getsockopt(fd, SOL_SOCKET, SO_TYPE, (char *)&v, &l) == 0);
 374 }
 375
 376
 377 static RETSIGTYPE sigchld_handler(UNUSED(int val))
 378 {
 379         signal(SIGCHLD, sigchld_handler);
 380 #ifdef WNOHANG
 381         while (waitpid(-1, NULL, WNOHANG) > 0) {}
 382 #endif
 383 }
 384
 385
 386 void start_accept_loop(int port, int (*fn)(int, int))
 387 {
 388         int s;
 389         extern char *bind_address;
 390         extern int default_af_hint;
 391
 392         /* open an incoming socket */
 393         s = open_socket_in(SOCK_STREAM, port, bind_address, default_af_hint);
 394         if (s == -1)
 395                 exit_cleanup(RERR_SOCKETIO);
 396
 397         /* ready to listen */
 398         if (listen(s, 5) == -1) {
 399                 close(s);
 400                 exit_cleanup(RERR_SOCKETIO);
 401         }
 402
 403
 404         /* now accept incoming connections - forking a new process
 405            for each incoming connection */
 406         while (1) {
 407                 fd_set fds;
 408                 pid_t pid;
 409                 int fd;
 410                 struct sockaddr_storage addr;
 411                 socklen_t addrlen = sizeof addr;
 412
 413                 /* close log file before the potentially very long select so
 414                    file can be trimmed by another process instead of growing
 415                    forever */
 416                 log_close();
 417
 418                 FD_ZERO(&fds);
 419                 FD_SET(s, &fds);
 420
 421                 if (select(s+1, &fds, NULL, NULL, NULL) != 1) {
 422                         continue;
 423                 }
 424
 425                 if(!FD_ISSET(s, &fds)) continue;
 426
 427                 fd = accept(s,(struct sockaddr *)&addr,&addrlen);
 428
 429                 if (fd == -1) continue;
 430
 431                 signal(SIGCHLD, sigchld_handler);
 432
 433                 if ((pid = fork()) == 0) {
 434                         int ret;
 435                         close(s);
 436                         /* open log file in child before possibly giving
 437                            up privileges  */
 438                         log_open();
 439                         ret = fn(fd, fd);
 440                         close_all();
 441                         _exit(ret);
 442                 } else if (pid < 0) {
 443                         rprintf(FERROR,
 444                                 RSYNC_NAME
 445                                 ": could not create child server process: %s\n",
 446                                 strerror(errno));
 447                         close(fd);
 448                         /* This might have happened because we're
 449                          * overloaded.  Sleep briefly before trying to
 450                          * accept again. */
 451                         sleep(2);
 452                 } else {
 453                         /* Parent doesn't need this fd anymore. */
 454                         close(fd);
 455                 }
 456         }
 457 }
 458
 459
 460 enum SOCK_OPT_TYPES {OPT_BOOL,OPT_INT,OPT_ON};
 461
 462 struct
 463 {
 464   char *name;
 465   int level;
 466   int option;
 467   int value;
 468   int opttype;
 469 } socket_options[] = {
 470   {"SO_KEEPALIVE",      SOL_SOCKET,    SO_KEEPALIVE,    0,                 OPT_BOOL},
 471   {"SO_REUSEADDR",      SOL_SOCKET,    SO_REUSEADDR,    0,                 OPT_BOOL},
 472   {"SO_BROADCAST",      SOL_SOCKET,    SO_BROADCAST,    0,                 OPT_BOOL},
 473 #ifdef TCP_NODELAY
 474   {"TCP_NODELAY",       IPPROTO_TCP,   TCP_NODELAY,     0,                 OPT_BOOL},
 475 #endif
 476 #ifdef IPTOS_LOWDELAY
 477   {"IPTOS_LOWDELAY",    IPPROTO_IP,    IP_TOS,          IPTOS_LOWDELAY,    OPT_ON},
 478 #endif
 479 #ifdef IPTOS_THROUGHPUT
 480   {"IPTOS_THROUGHPUT",  IPPROTO_IP,    IP_TOS,          IPTOS_THROUGHPUT,  OPT_ON},
 481 #endif
 482 #ifdef SO_SNDBUF
 483   {"SO_SNDBUF",         SOL_SOCKET,    SO_SNDBUF,       0,                 OPT_INT},
 484 #endif
 485 #ifdef SO_RCVBUF
 486   {"SO_RCVBUF",         SOL_SOCKET,    SO_RCVBUF,       0,                 OPT_INT},
 487 #endif
 488 #ifdef SO_SNDLOWAT
 489   {"SO_SNDLOWAT",       SOL_SOCKET,    SO_SNDLOWAT,     0,                 OPT_INT},
 490 #endif
 491 #ifdef SO_RCVLOWAT
 492   {"SO_RCVLOWAT",       SOL_SOCKET,    SO_RCVLOWAT,     0,                 OPT_INT},
 493 #endif
 494 #ifdef SO_SNDTIMEO
 495   {"SO_SNDTIMEO",       SOL_SOCKET,    SO_SNDTIMEO,     0,                 OPT_INT},
 496 #endif
 497 #ifdef SO_RCVTIMEO
 498   {"SO_RCVTIMEO",       SOL_SOCKET,    SO_RCVTIMEO,     0,                 OPT_INT},
 499 #endif
 500   {NULL,0,0,0,0}};
 501
 502
 503
 504 /**
 505  * Set user socket options
 506  **/
 507 void set_socket_options(int fd, char *options)
 508 {
 509         char *tok;
 510         if (!options || !*options) return;
 511
 512         options = strdup(options);
 513
 514         if (!options) out_of_memory("set_socket_options");
 515
 516         for (tok=strtok(options, " \t,"); tok; tok=strtok(NULL," \t,")) {
 517                 int ret=0,i;
 518                 int value = 1;
 519                 char *p;
 520                 int got_value = 0;
 521
 522                 if ((p = strchr(tok,'='))) {
 523                         *p = 0;
 524                         value = atoi(p+1);
 525                         got_value = 1;
 526                 }
 527
 528                 for (i=0;socket_options[i].name;i++)
 529                         if (strcmp(socket_options[i].name,tok)==0)
 530                                 break;
 531
 532                 if (!socket_options[i].name) {
 533                         rprintf(FERROR,"Unknown socket option %s\n",tok);
 534                         continue;
 535                 }
 536
 537                 switch (socket_options[i].opttype) {
 538                 case OPT_BOOL:
 539                 case OPT_INT:
 540                         ret = setsockopt(fd,socket_options[i].level,
 541                                          socket_options[i].option,(char *)&value,sizeof(int));
 542                         break;
 543
 544                 case OPT_ON:
 545                         if (got_value)
 546                                 rprintf(FERROR,"syntax error - %s does not take a value\n",tok);
 547
 548                         {
 549                                 int on = socket_options[i].value;
 550                                 ret = setsockopt(fd,socket_options[i].level,
 551                                                  socket_options[i].option,(char *)&on,sizeof(int));
 552                         }
 553                         break;
 554                 }
 555
 556                 if (ret != 0)
 557                         rprintf(FERROR, "failed to set socket option %s: %s\n", tok,
 558                                 strerror(errno));
 559         }
 560
 561         free(options);
 562 }
 563
 564 /**
 565  * Become a daemon, discarding the controlling terminal
 566  **/
 567 void become_daemon(void)
 568 {
 569         int i;
 570
 571         if (fork()) {
 572                 _exit(0);
 573         }
 574
 575         /* detach from the terminal */
 576 #ifdef HAVE_SETSID
 577         setsid();
 578 #else
 579 #ifdef TIOCNOTTY
 580         i = open("/dev/tty", O_RDWR);
 581         if (i >= 0) {
 582                 ioctl(i, (int) TIOCNOTTY, (char *)0);
 583                 close(i);
 584         }
 585 #endif /* TIOCNOTTY */
 586 #endif
 587         /* make sure that stdin, stdout an stderr don't stuff things
 588            up (library functions, for example) */
 589         for (i=0;i<3;i++) {
 590                 close(i);
 591                 open("/dev/null", O_RDWR);
 592         }
 593 }
 594
 595
 596 /**
 597  * This is like socketpair but uses tcp. It is used by the Samba
 598  * regression test code.
 599  *
 600  * The function guarantees that nobody else can attach to the socket,
 601  * or if they do that this function fails and the socket gets closed
 602  * returns 0 on success, -1 on failure the resulting file descriptors
 603  * are symmetrical.
 604  **/
 605 static int socketpair_tcp(int fd[2])
 606 {
 607         int listener;
 608         struct sockaddr_in sock;
 609         struct sockaddr_in sock2;
 610         socklen_t socklen = sizeof(sock);
 611         int connect_done = 0;
 612
 613         fd[0] = fd[1] = listener = -1;
 614
 615         memset(&sock, 0, sizeof(sock));
 616
 617         if ((listener = socket(PF_INET, SOCK_STREAM, 0)) == -1) goto failed;
 618
 619         memset(&sock2, 0, sizeof(sock2));
 620 #ifdef HAVE_SOCKADDR_LEN
 621         sock2.sin_len = sizeof(sock2);
 622 #endif
 623         sock2.sin_family = PF_INET;
 624
 625         bind(listener, (struct sockaddr *)&sock2, sizeof(sock2));
 626
 627         if (listen(listener, 1) != 0) goto failed;
 628
 629         if (getsockname(listener, (struct sockaddr *)&sock, &socklen) != 0) goto failed;
 630
 631         if ((fd[1] = socket(PF_INET, SOCK_STREAM, 0)) == -1) goto failed;
 632
 633         set_nonblocking(fd[1]);
 634
 635         sock.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
 636
 637         if (connect(fd[1],(struct sockaddr *)&sock,sizeof(sock)) == -1) {
 638                 if (errno != EINPROGRESS) goto failed;
 639         } else {
 640                 connect_done = 1;
 641         }
 642
 643         if ((fd[0] = accept(listener, (struct sockaddr *)&sock, &socklen)) == -1) goto failed;
 644
 645         close(listener);
 646         if (connect_done == 0) {
 647                 if (connect(fd[1],(struct sockaddr *)&sock,sizeof(sock)) != 0
 648                     && errno != EISCONN) goto failed;
 649         }
 650
 651         set_blocking (fd[1]);
 652
 653         /* all OK! */
 654         return 0;
 655
 656  failed:
 657         if (fd[0] != -1) close(fd[0]);
 658         if (fd[1] != -1) close(fd[1]);
 659         if (listener != -1) close(listener);
 660         return -1;
 661 }
 662
 663
 664
 665 /**
 666  * Run a program on a local tcp socket, so that we can talk to it's
 667  * stdin and stdout.  This is used to fake a connection to a daemon
 668  * for testing -- not for the normal case of running SSH.
 669  *
 670  * @return a socket which is attached to a subprocess running
 671  * "prog". stdin and stdout are attached. stderr is left attached to
 672  * the original stderr
 673  **/
 674 int sock_exec(const char *prog)
 675 {
 676         int fd[2];
 677
 678         if (socketpair_tcp(fd) != 0) {
 679                 rprintf (FERROR, RSYNC_NAME
 680                          ": socketpair_tcp failed (%s)\n",
 681                          strerror(errno));
 682                 return -1;
 683         }
 684         if (fork() == 0) {
 685                 close(fd[0]);
 686                 close(0);
 687                 close(1);
 688                 dup(fd[1]);
 689                 dup(fd[1]);
 690                 if (verbose > 3) {
 691                         /* Can't use rprintf because we've forked. */
 692                         fprintf (stderr,
 693                                  RSYNC_NAME ": execute socket program \"%s\"\n",
 694                                  prog);
 695                 }
 696                 exit (system (prog));
 697         }
 698         close (fd[1]);
 699         return fd[0];
 700 }
 701
 702
 703