socket.c

   1 /* -*- c-file-style: "linux" -*-
   2
   3    Copyright (C) 1998-2001 by Andrew Tridgell
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18 */
  19
  20 /*
  21   socket functions used in rsync
  22
  23   */
  24
  25 #include "rsync.h"
  26
  27
  28 /* Establish a proxy connection on an open socket to a web roxy by
  29  * using the CONNECT method. */
  30 static int establish_proxy_connection(int fd, char *host, int port)
  31 {
  32         char buffer[1024];
  33         char *cp;
  34
  35         snprintf(buffer, sizeof(buffer), "CONNECT %s:%d HTTP/1.0\r\n\r\n", host, port);
  36         if (write(fd, buffer, strlen(buffer)) != strlen(buffer)) {
  37                 rprintf(FERROR, "failed to write to proxy: %s\n",
  38                         strerror(errno));
  39                 return -1;
  40         }
  41
  42         for (cp = buffer; cp < &buffer[sizeof(buffer) - 1]; cp++) {
  43                 if (read(fd, cp, 1) != 1) {
  44                         rprintf(FERROR, "failed to read from proxy: %s\n",
  45                                 strerror(errno));
  46                         return -1;
  47                 }
  48                 if (*cp == '\n')
  49                         break;
  50         }
  51
  52         if (*cp != '\n')
  53                 cp++;
  54         *cp-- = '\0';
  55         if (*cp == '\r')
  56                 *cp = '\0';
  57         if (strncmp(buffer, "HTTP/", 5) != 0) {
  58                 rprintf(FERROR, "bad response from proxy - %s\n",
  59                         buffer);
  60                 return -1;
  61         }
  62         for (cp = &buffer[5]; isdigit(*cp) || (*cp == '.'); cp++)
  63                 ;
  64         while (*cp == ' ')
  65                 cp++;
  66         if (*cp != '2') {
  67                 rprintf(FERROR, "bad response from proxy - %s\n",
  68                         buffer);
  69                 return -1;
  70         }
  71         /* throw away the rest of the HTTP header */
  72         while (1) {
  73                 for (cp = buffer; cp < &buffer[sizeof(buffer) - 1];
  74                      cp++) {
  75                         if (read(fd, cp, 1) != 1) {
  76                                 rprintf(FERROR, "failed to read from proxy: %s\n",
  77                                         strerror(errno));
  78                                 return -1;
  79                         }
  80                         if (*cp == '\n')
  81                                 break;
  82                 }
  83                 if ((cp > buffer) && (*cp == '\n'))
  84                         cp--;
  85                 if ((cp == buffer) && ((*cp == '\n') || (*cp == '\r')))
  86                         break;
  87         }
  88         return 0;
  89 }
  90
  91
  92 /* open a socket to a tcp remote host with the specified port
  93    based on code from Warren
  94    proxy support by Stephen Rothwell */
  95 int open_socket_out(char *host, int port, struct in_addr *address)
  96 {
  97         int type = SOCK_STREAM;
  98         struct sockaddr_in sock_out;
  99         struct sockaddr_in sock;
 100         int res;
 101         struct hostent *hp;
 102         char *h;
 103         unsigned p;
 104         int proxied = 0;
 105         char buffer[1024];
 106         char *cp;
 107
 108         /* if we have a RSYNC_PROXY env variable then redirect our
 109          * connetcion via a web proxy at the given address. The format
 110          * is hostname:port */
 111         h = getenv("RSYNC_PROXY");
 112         proxied = (h != NULL) && (*h != '\0');
 113
 114         if (proxied) {
 115                 strlcpy(buffer, h, sizeof(buffer));
 116                 cp = strchr(buffer, ':');
 117                 if (cp == NULL) {
 118                         rprintf(FERROR,
 119                                 "invalid proxy specification: should be HOST:PORT\n");
 120                         return -1;
 121                 }
 122                 *cp++ = '\0';
 123                 p = atoi(cp);
 124                 h = buffer;
 125         } else {
 126                 h = host;
 127                 p = port;
 128         }
 129
 130         res = socket(PF_INET, type, 0);
 131         if (res == -1) {
 132                 return -1;
 133         }
 134
 135         hp = gethostbyname(h);
 136         if (!hp) {
 137                 rprintf(FERROR,"unknown host: %s\n", h);
 138                 close(res);
 139                 return -1;
 140         }
 141
 142         memcpy(&sock_out.sin_addr, hp->h_addr, hp->h_length);
 143         sock_out.sin_port = htons(p);
 144         sock_out.sin_family = PF_INET;
 145
 146         if (address) {
 147                 sock.sin_addr = *address;
 148                 sock.sin_port = 0;
 149                 sock.sin_family = hp->h_addrtype;
 150                 bind(res, (struct sockaddr * ) &sock,sizeof(sock));
 151         }
 152
 153         if (connect(res,(struct sockaddr *)&sock_out,sizeof(sock_out))) {
 154                 rprintf(FERROR,"failed to connect to %s - %s\n", h, strerror(errno));
 155                 close(res);
 156                 return -1;
 157         }
 158
 159         if (proxied && establish_proxy_connection(res, host, port) != 0) {
 160                 close(res);
 161                 return -1;
 162         }
 163
 164         return res;
 165 }
 166
 167
 168 /****************************************************************************
 169 open a socket of the specified type, port and address for incoming data
 170 ****************************************************************************/
 171 static int open_socket_in(int type, int port, struct in_addr *address)
 172 {
 173         struct hostent *hp;
 174         struct sockaddr_in sock;
 175         char host_name[MAXHOSTNAMELEN];
 176         int res;
 177         int one=1;
 178
 179         /* get my host name */
 180         if (gethostname(host_name, sizeof(host_name)) == -1) {
 181                 rprintf(FERROR,"gethostname failed\n");
 182                 return -1;
 183         }
 184
 185         /* get host info */
 186         if ((hp = gethostbyname(host_name)) == 0) {
 187                 rprintf(FERROR,"gethostbyname: Unknown host %s\n",host_name);
 188                 return -1;
 189         }
 190
 191         memset((char *)&sock,0,sizeof(sock));
 192         memcpy((char *)&sock.sin_addr,(char *)hp->h_addr, hp->h_length);
 193         sock.sin_port = htons(port);
 194         sock.sin_family = hp->h_addrtype;
 195         if (address) {
 196                 sock.sin_addr = *address;
 197         } else {
 198                 sock.sin_addr.s_addr = INADDR_ANY;
 199         }
 200         res = socket(hp->h_addrtype, type, 0);
 201         if (res == -1) {
 202                 rprintf(FERROR,"socket failed: %s\n",
 203                         strerror(errno));
 204                 return -1;
 205         }
 206
 207         setsockopt(res,SOL_SOCKET,SO_REUSEADDR,(char *)&one,sizeof(one));
 208
 209         /* now we've got a socket - we need to bind it */
 210         if (bind(res, (struct sockaddr * ) &sock,sizeof(sock)) == -1) {
 211                 rprintf(FERROR,"bind failed on port %d: %s\n", port,
 212                         strerror(errno));
 213                 if (errno == EACCES && port < 1024) {
 214                         rprintf(FERROR, "Note: you must be root to bind "
 215                                 "to low-numbered ports");
 216                 }
 217                 close(res);
 218                 return -1;
 219         }
 220
 221         return res;
 222 }
 223
 224
 225 /*
 226  * Determine if a file descriptor is in fact a socket
 227  */
 228 int is_a_socket(int fd)
 229 {
 230         int v;
 231         socklen_t l;
 232         l = sizeof(int);
 233
 234         /* Parameters to getsockopt, setsockopt etc are very
 235          * unstandardized across platforms, so don't be surprised if
 236          * there are compiler warnings on e.g. SCO OpenSwerver or AIX.
 237          * It seems they all eventually get the right idea.
 238          *
 239          * Debian says: ``The fifth argument of getsockopt and
 240          * setsockopt is in reality an int [*] (and this is what BSD
 241          * 4.* and libc4 and libc5 have).  Some POSIX confusion
 242          * resulted in the present socklen_t.  The draft standard has
 243          * not been adopted yet, but glibc2 already follows it and
 244          * also has socklen_t [*]. See also accept(2).''
 245          *
 246          * We now return to your regularly scheduled programming.  */
 247         return(getsockopt(fd, SOL_SOCKET, SO_TYPE, (char *)&v, &l) == 0);
 248 }
 249
 250
 251 void start_accept_loop(int port, int (*fn)(int ))
 252 {
 253         int s;
 254         extern struct in_addr socket_address;
 255
 256         /* open an incoming socket */
 257         s = open_socket_in(SOCK_STREAM, port, &socket_address);
 258         if (s == -1)
 259                 exit_cleanup(RERR_SOCKETIO);
 260
 261         /* ready to listen */
 262         if (listen(s, 5) == -1) {
 263                 close(s);
 264                 exit_cleanup(RERR_SOCKETIO);
 265         }
 266
 267
 268         /* now accept incoming connections - forking a new process
 269            for each incoming connection */
 270         while (1) {
 271                 fd_set fds;
 272                 int fd;
 273                 struct sockaddr addr;
 274                 int in_addrlen = sizeof(addr);
 275
 276                 /* close log file before the potentially very long select so
 277                    file can be trimmed by another process instead of growing
 278                    forever */
 279                 log_close();
 280
 281                 FD_ZERO(&fds);
 282                 FD_SET(s, &fds);
 283
 284                 if (select(s+1, &fds, NULL, NULL, NULL) != 1) {
 285                         continue;
 286                 }
 287
 288                 if(!FD_ISSET(s, &fds)) continue;
 289
 290                 /* See note above prototypes. */
 291                 fd = accept(s,&addr,&in_addrlen);
 292
 293                 if (fd == -1) continue;
 294
 295                 signal(SIGCHLD, SIG_IGN);
 296
 297                 /* we shouldn't have any children left hanging around
 298                    but I have had reports that on Digital Unix zombies
 299                    are produced, so this ensures that they are reaped */
 300 #ifdef WNOHANG
 301                 while (waitpid(-1, NULL, WNOHANG) > 0);
 302 #endif
 303
 304                 if (fork()==0) {
 305                         close(s);
 306
 307                         /* open log file in child before possibly giving
 308                            up privileges  */
 309                         log_open();
 310
 311                         _exit(fn(fd));
 312                 }
 313
 314                 close(fd);
 315         }
 316 }
 317
 318
 319 enum SOCK_OPT_TYPES {OPT_BOOL,OPT_INT,OPT_ON};
 320
 321 struct
 322 {
 323   char *name;
 324   int level;
 325   int option;
 326   int value;
 327   int opttype;
 328 } socket_options[] = {
 329   {"SO_KEEPALIVE",      SOL_SOCKET,    SO_KEEPALIVE,    0,                 OPT_BOOL},
 330   {"SO_REUSEADDR",      SOL_SOCKET,    SO_REUSEADDR,    0,                 OPT_BOOL},
 331   {"SO_BROADCAST",      SOL_SOCKET,    SO_BROADCAST,    0,                 OPT_BOOL},
 332 #ifdef TCP_NODELAY
 333   {"TCP_NODELAY",       IPPROTO_TCP,   TCP_NODELAY,     0,                 OPT_BOOL},
 334 #endif
 335 #ifdef IPTOS_LOWDELAY
 336   {"IPTOS_LOWDELAY",    IPPROTO_IP,    IP_TOS,          IPTOS_LOWDELAY,    OPT_ON},
 337 #endif
 338 #ifdef IPTOS_THROUGHPUT
 339   {"IPTOS_THROUGHPUT",  IPPROTO_IP,    IP_TOS,          IPTOS_THROUGHPUT,  OPT_ON},
 340 #endif
 341 #ifdef SO_SNDBUF
 342   {"SO_SNDBUF",         SOL_SOCKET,    SO_SNDBUF,       0,                 OPT_INT},
 343 #endif
 344 #ifdef SO_RCVBUF
 345   {"SO_RCVBUF",         SOL_SOCKET,    SO_RCVBUF,       0,                 OPT_INT},
 346 #endif
 347 #ifdef SO_SNDLOWAT
 348   {"SO_SNDLOWAT",       SOL_SOCKET,    SO_SNDLOWAT,     0,                 OPT_INT},
 349 #endif
 350 #ifdef SO_RCVLOWAT
 351   {"SO_RCVLOWAT",       SOL_SOCKET,    SO_RCVLOWAT,     0,                 OPT_INT},
 352 #endif
 353 #ifdef SO_SNDTIMEO
 354   {"SO_SNDTIMEO",       SOL_SOCKET,    SO_SNDTIMEO,     0,                 OPT_INT},
 355 #endif
 356 #ifdef SO_RCVTIMEO
 357   {"SO_RCVTIMEO",       SOL_SOCKET,    SO_RCVTIMEO,     0,                 OPT_INT},
 358 #endif
 359   {NULL,0,0,0,0}};
 360
 361
 362
 363 /****************************************************************************
 364 set user socket options
 365 ****************************************************************************/
 366 void set_socket_options(int fd, char *options)
 367 {
 368         char *tok;
 369         if (!options || !*options) return;
 370
 371         options = strdup(options);
 372
 373         if (!options) out_of_memory("set_socket_options");
 374
 375         for (tok=strtok(options, " \t,"); tok; tok=strtok(NULL," \t,")) {
 376                 int ret=0,i;
 377                 int value = 1;
 378                 char *p;
 379                 int got_value = 0;
 380
 381                 if ((p = strchr(tok,'='))) {
 382                         *p = 0;
 383                         value = atoi(p+1);
 384                         got_value = 1;
 385                 }
 386
 387                 for (i=0;socket_options[i].name;i++)
 388                         if (strcmp(socket_options[i].name,tok)==0)
 389                                 break;
 390
 391                 if (!socket_options[i].name) {
 392                         rprintf(FERROR,"Unknown socket option %s\n",tok);
 393                         continue;
 394                 }
 395
 396                 switch (socket_options[i].opttype) {
 397                 case OPT_BOOL:
 398                 case OPT_INT:
 399                         ret = setsockopt(fd,socket_options[i].level,
 400                                          socket_options[i].option,(char *)&value,sizeof(int));
 401                         break;
 402
 403                 case OPT_ON:
 404                         if (got_value)
 405                                 rprintf(FERROR,"syntax error - %s does not take a value\n",tok);
 406
 407                         {
 408                                 int on = socket_options[i].value;
 409                                 ret = setsockopt(fd,socket_options[i].level,
 410                                                  socket_options[i].option,(char *)&on,sizeof(int));
 411                         }
 412                         break;
 413                 }
 414
 415                 if (ret != 0)
 416                         rprintf(FERROR, "failed to set socket option %s: %s\n", tok,
 417                                 strerror(errno));
 418         }
 419
 420         free(options);
 421 }
 422
 423 /****************************************************************************
 424 become a daemon, discarding the controlling terminal
 425 ****************************************************************************/
 426 void become_daemon(void)
 427 {
 428         int i;
 429
 430         if (fork()) {
 431                 _exit(0);
 432         }
 433
 434         /* detach from the terminal */
 435 #ifdef HAVE_SETSID
 436         setsid();
 437 #else
 438 #ifdef TIOCNOTTY
 439         i = open("/dev/tty", O_RDWR);
 440         if (i >= 0) {
 441                 ioctl(i, (int) TIOCNOTTY, (char *)0);
 442                 close(i);
 443         }
 444 #endif /* TIOCNOTTY */
 445 #endif
 446         /* make sure that stdin, stdout an stderr don't stuff things
 447            up (library functions, for example) */
 448         for (i=0;i<3;i++) {
 449                 close(i);
 450                 open("/dev/null", O_RDWR);
 451         }
 452 }
 453
 454 /*******************************************************************
 455  return the IP addr of the client as a string
 456  ******************************************************************/
 457 char *client_addr(int fd)
 458 {
 459         struct sockaddr sa;
 460         struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
 461         int     length = sizeof(sa);
 462         static char addr_buf[100];
 463         static int initialised;
 464
 465         if (initialised) return addr_buf;
 466
 467         initialised = 1;
 468
 469         if (getpeername(fd, &sa, &length)) {
 470                 exit_cleanup(RERR_SOCKETIO);
 471         }
 472
 473         strlcpy(addr_buf,(char *)inet_ntoa(sockin->sin_addr), sizeof(addr_buf));
 474         return addr_buf;
 475 }
 476
 477
 478 /*******************************************************************
 479  return the DNS name of the client
 480  ******************************************************************/
 481 char *client_name(int fd)
 482 {
 483         struct sockaddr sa;
 484         struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
 485         int     length = sizeof(sa);
 486         static char name_buf[100];
 487         struct hostent *hp;
 488         char **p;
 489         char *def = "UNKNOWN";
 490         static int initialised;
 491
 492         if (initialised) return name_buf;
 493
 494         initialised = 1;
 495
 496         strcpy(name_buf,def);
 497
 498         if (getpeername(fd, &sa, &length)) {
 499                 exit_cleanup(RERR_SOCKETIO);
 500         }
 501
 502         /* Look up the remote host name. */
 503         if ((hp = gethostbyaddr((char *) &sockin->sin_addr,
 504                                 sizeof(sockin->sin_addr),
 505                                 AF_INET))) {
 506                 strlcpy(name_buf,(char *)hp->h_name,sizeof(name_buf));
 507         }
 508
 509
 510         /* do a forward lookup as well to prevent spoofing */
 511         hp = gethostbyname(name_buf);
 512         if (!hp) {
 513                 strcpy(name_buf,def);
 514                 rprintf(FERROR,"reverse name lookup failed\n");
 515         } else {
 516                 for (p=hp->h_addr_list;*p;p++) {
 517                         if (memcmp(*p, &sockin->sin_addr, hp->h_length) == 0) {
 518                                 break;
 519                         }
 520                 }
 521                 if (!*p) {
 522                         strcpy(name_buf,def);
 523                         rprintf(FERROR,"reverse name lookup mismatch - spoofed address?\n");
 524                 }
 525         }
 526
 527         return name_buf;
 528 }
 529
 530 /*******************************************************************
 531 convert a string to an IP address. The string can be a name or
 532 dotted decimal number
 533   ******************************************************************/
 534 struct in_addr *ip_address(const char *str)
 535 {
 536         static struct in_addr ret;
 537         struct hostent *hp;
 538
 539         /* try as an IP address */
 540         if (inet_aton(str, &ret) != 0) {
 541                 return &ret;
 542         }
 543
 544         /* otherwise assume it's a network name of some sort and use
 545            gethostbyname */
 546         if ((hp = gethostbyname(str)) == 0) {
 547                 rprintf(FERROR, "gethostbyname: Unknown host. %s\n",str);
 548                 return NULL;
 549         }
 550
 551         if (hp->h_addr == NULL) {
 552                 rprintf(FERROR, "gethostbyname: host address is invalid for host %s\n",str);
 553                 return NULL;
 554         }
 555
 556         if (hp->h_length > sizeof(ret)) {
 557                 rprintf(FERROR, "gethostbyname: host address is too large\n");
 558                 return NULL;
 559         }
 560
 561         memcpy(&ret.s_addr, hp->h_addr, hp->h_length);
 562
 563         return(&ret);
 564 }