socket.c

   1 /* -*- c-file-style: "linux" -*-
   2
   3    Copyright (C) 1998-2001 by Andrew Tridgell <tridge@samba.org>
   4    Copyright (C) 2001 by Martin Pool <mbp@samba.org>
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 /*
  22   socket functions used in rsync
  23
  24   */
  25
  26 #include "rsync.h"
  27
  28
  29 /* Establish a proxy connection on an open socket to a web roxy by
  30  * using the CONNECT method. */
  31 static int establish_proxy_connection(int fd, char *host, int port)
  32 {
  33         char buffer[1024];
  34         char *cp;
  35
  36         snprintf(buffer, sizeof(buffer), "CONNECT %s:%d HTTP/1.0\r\n\r\n", host, port);
  37         if (write(fd, buffer, strlen(buffer)) != strlen(buffer)) {
  38                 rprintf(FERROR, "failed to write to proxy: %s\n",
  39                         strerror(errno));
  40                 return -1;
  41         }
  42
  43         for (cp = buffer; cp < &buffer[sizeof(buffer) - 1]; cp++) {
  44                 if (read(fd, cp, 1) != 1) {
  45                         rprintf(FERROR, "failed to read from proxy: %s\n",
  46                                 strerror(errno));
  47                         return -1;
  48                 }
  49                 if (*cp == '\n')
  50                         break;
  51         }
  52
  53         if (*cp != '\n')
  54                 cp++;
  55         *cp-- = '\0';
  56         if (*cp == '\r')
  57                 *cp = '\0';
  58         if (strncmp(buffer, "HTTP/", 5) != 0) {
  59                 rprintf(FERROR, "bad response from proxy - %s\n",
  60                         buffer);
  61                 return -1;
  62         }
  63         for (cp = &buffer[5]; isdigit(*cp) || (*cp == '.'); cp++)
  64                 ;
  65         while (*cp == ' ')
  66                 cp++;
  67         if (*cp != '2') {
  68                 rprintf(FERROR, "bad response from proxy - %s\n",
  69                         buffer);
  70                 return -1;
  71         }
  72         /* throw away the rest of the HTTP header */
  73         while (1) {
  74                 for (cp = buffer; cp < &buffer[sizeof(buffer) - 1];
  75                      cp++) {
  76                         if (read(fd, cp, 1) != 1) {
  77                                 rprintf(FERROR, "failed to read from proxy: %s\n",
  78                                         strerror(errno));
  79                                 return -1;
  80                         }
  81                         if (*cp == '\n')
  82                                 break;
  83                 }
  84                 if ((cp > buffer) && (*cp == '\n'))
  85                         cp--;
  86                 if ((cp == buffer) && ((*cp == '\n') || (*cp == '\r')))
  87                         break;
  88         }
  89         return 0;
  90 }
  91
  92
  93 /* open a socket to a tcp remote host with the specified port
  94    based on code from Warren
  95    proxy support by Stephen Rothwell */
  96 int open_socket_out(char *host, int port, struct in_addr *address)
  97 {
  98         int type = SOCK_STREAM;
  99         struct sockaddr_in sock_out;
 100         struct sockaddr_in sock;
 101         int res;
 102         struct hostent *hp;
 103         char *h;
 104         unsigned p;
 105         int proxied = 0;
 106         char buffer[1024];
 107         char *cp;
 108
 109         /* if we have a RSYNC_PROXY env variable then redirect our
 110          * connetcion via a web proxy at the given address. The format
 111          * is hostname:port */
 112         h = getenv("RSYNC_PROXY");
 113         proxied = (h != NULL) && (*h != '\0');
 114
 115         if (proxied) {
 116                 strlcpy(buffer, h, sizeof(buffer));
 117                 cp = strchr(buffer, ':');
 118                 if (cp == NULL) {
 119                         rprintf(FERROR,
 120                                 "invalid proxy specification: should be HOST:PORT\n");
 121                         return -1;
 122                 }
 123                 *cp++ = '\0';
 124                 p = atoi(cp);
 125                 h = buffer;
 126         } else {
 127                 h = host;
 128                 p = port;
 129         }
 130
 131         res = socket(PF_INET, type, 0);
 132         if (res == -1) {
 133                 return -1;
 134         }
 135
 136         hp = gethostbyname(h);
 137         if (!hp) {
 138                 rprintf(FERROR,"unknown host: \"%s\"\n", h);
 139                 close(res);
 140                 return -1;
 141         }
 142
 143         memcpy(&sock_out.sin_addr, hp->h_addr, hp->h_length);
 144         sock_out.sin_port = htons(p);
 145         sock_out.sin_family = PF_INET;
 146
 147         if (address) {
 148                 sock.sin_addr = *address;
 149                 sock.sin_port = 0;
 150                 sock.sin_family = hp->h_addrtype;
 151                 bind(res, (struct sockaddr * ) &sock,sizeof(sock));
 152         }
 153
 154         if (connect(res,(struct sockaddr *)&sock_out,sizeof(sock_out))) {
 155                 rprintf(FERROR,"failed to connect to %s - %s\n", h, strerror(errno));
 156                 close(res);
 157                 return -1;
 158         }
 159
 160         if (proxied && establish_proxy_connection(res, host, port) != 0) {
 161                 close(res);
 162                 return -1;
 163         }
 164
 165         return res;
 166 }
 167
 168
 169 /****************************************************************************
 170 open a socket of the specified type, port and address for incoming data
 171 ****************************************************************************/
 172 static int open_socket_in(int type, int port, struct in_addr *address)
 173 {
 174         struct sockaddr_in sock;
 175         int res;
 176         int one=1;
 177
 178         memset((char *)&sock,0,sizeof(sock));
 179         sock.sin_port = htons(port);
 180         sock.sin_family = AF_INET;
 181         if (address) {
 182                 sock.sin_addr = *address;
 183         } else {
 184                 sock.sin_addr.s_addr = INADDR_ANY;
 185         }
 186         res = socket(AF_INET, type, 0);
 187         if (res == -1) {
 188                 rprintf(FERROR,"socket failed: %s\n",
 189                         strerror(errno));
 190                 return -1;
 191         }
 192
 193         setsockopt(res,SOL_SOCKET,SO_REUSEADDR,(char *)&one,sizeof(one));
 194
 195         /* now we've got a socket - we need to bind it */
 196         if (bind(res, (struct sockaddr * ) &sock,sizeof(sock)) == -1) {
 197                 rprintf(FERROR,"bind failed on port %d: %s\n", port,
 198                         strerror(errno));
 199                 if (errno == EACCES && port < 1024) {
 200                         rprintf(FERROR, "Note: you must be root to bind "
 201                                 "to low-numbered ports");
 202                 }
 203                 close(res);
 204                 return -1;
 205         }
 206
 207         return res;
 208 }
 209
 210
 211 /*
 212  * Determine if a file descriptor is in fact a socket
 213  */
 214 int is_a_socket(int fd)
 215 {
 216         int v;
 217         socklen_t l;
 218         l = sizeof(int);
 219
 220         /* Parameters to getsockopt, setsockopt etc are very
 221          * unstandardized across platforms, so don't be surprised if
 222          * there are compiler warnings on e.g. SCO OpenSwerver or AIX.
 223          * It seems they all eventually get the right idea.
 224          *
 225          * Debian says: ``The fifth argument of getsockopt and
 226          * setsockopt is in reality an int [*] (and this is what BSD
 227          * 4.* and libc4 and libc5 have).  Some POSIX confusion
 228          * resulted in the present socklen_t.  The draft standard has
 229          * not been adopted yet, but glibc2 already follows it and
 230          * also has socklen_t [*]. See also accept(2).''
 231          *
 232          * We now return to your regularly scheduled programming.  */
 233         return(getsockopt(fd, SOL_SOCKET, SO_TYPE, (char *)&v, &l) == 0);
 234 }
 235
 236
 237 void start_accept_loop(int port, int (*fn)(int ))
 238 {
 239         int s;
 240         extern struct in_addr socket_address;
 241
 242         /* open an incoming socket */
 243         s = open_socket_in(SOCK_STREAM, port, &socket_address);
 244         if (s == -1)
 245                 exit_cleanup(RERR_SOCKETIO);
 246
 247         /* ready to listen */
 248         if (listen(s, 5) == -1) {
 249                 close(s);
 250                 exit_cleanup(RERR_SOCKETIO);
 251         }
 252
 253
 254         /* now accept incoming connections - forking a new process
 255            for each incoming connection */
 256         while (1) {
 257                 fd_set fds;
 258                 int fd;
 259                 struct sockaddr addr;
 260                 socklen_t in_addrlen = sizeof(addr);
 261
 262                 /* close log file before the potentially very long select so
 263                    file can be trimmed by another process instead of growing
 264                    forever */
 265                 log_close();
 266
 267                 FD_ZERO(&fds);
 268                 FD_SET(s, &fds);
 269
 270                 if (select(s+1, &fds, NULL, NULL, NULL) != 1) {
 271                         continue;
 272                 }
 273
 274                 if(!FD_ISSET(s, &fds)) continue;
 275
 276                 /* See note above prototypes. */
 277                 fd = accept(s,&addr, &in_addrlen);
 278
 279                 if (fd == -1) continue;
 280
 281                 signal(SIGCHLD, SIG_IGN);
 282
 283                 /* we shouldn't have any children left hanging around
 284                    but I have had reports that on Digital Unix zombies
 285                    are produced, so this ensures that they are reaped */
 286 #ifdef WNOHANG
 287                 while (waitpid(-1, NULL, WNOHANG) > 0);
 288 #endif
 289
 290                 if (fork()==0) {
 291                         close(s);
 292
 293                         /* open log file in child before possibly giving
 294                            up privileges  */
 295                         log_open();
 296
 297                         _exit(fn(fd));
 298                 }
 299
 300                 close(fd);
 301         }
 302 }
 303
 304
 305 enum SOCK_OPT_TYPES {OPT_BOOL,OPT_INT,OPT_ON};
 306
 307 struct
 308 {
 309   char *name;
 310   int level;
 311   int option;
 312   int value;
 313   int opttype;
 314 } socket_options[] = {
 315   {"SO_KEEPALIVE",      SOL_SOCKET,    SO_KEEPALIVE,    0,                 OPT_BOOL},
 316   {"SO_REUSEADDR",      SOL_SOCKET,    SO_REUSEADDR,    0,                 OPT_BOOL},
 317   {"SO_BROADCAST",      SOL_SOCKET,    SO_BROADCAST,    0,                 OPT_BOOL},
 318 #ifdef TCP_NODELAY
 319   {"TCP_NODELAY",       IPPROTO_TCP,   TCP_NODELAY,     0,                 OPT_BOOL},
 320 #endif
 321 #ifdef IPTOS_LOWDELAY
 322   {"IPTOS_LOWDELAY",    IPPROTO_IP,    IP_TOS,          IPTOS_LOWDELAY,    OPT_ON},
 323 #endif
 324 #ifdef IPTOS_THROUGHPUT
 325   {"IPTOS_THROUGHPUT",  IPPROTO_IP,    IP_TOS,          IPTOS_THROUGHPUT,  OPT_ON},
 326 #endif
 327 #ifdef SO_SNDBUF
 328   {"SO_SNDBUF",         SOL_SOCKET,    SO_SNDBUF,       0,                 OPT_INT},
 329 #endif
 330 #ifdef SO_RCVBUF
 331   {"SO_RCVBUF",         SOL_SOCKET,    SO_RCVBUF,       0,                 OPT_INT},
 332 #endif
 333 #ifdef SO_SNDLOWAT
 334   {"SO_SNDLOWAT",       SOL_SOCKET,    SO_SNDLOWAT,     0,                 OPT_INT},
 335 #endif
 336 #ifdef SO_RCVLOWAT
 337   {"SO_RCVLOWAT",       SOL_SOCKET,    SO_RCVLOWAT,     0,                 OPT_INT},
 338 #endif
 339 #ifdef SO_SNDTIMEO
 340   {"SO_SNDTIMEO",       SOL_SOCKET,    SO_SNDTIMEO,     0,                 OPT_INT},
 341 #endif
 342 #ifdef SO_RCVTIMEO
 343   {"SO_RCVTIMEO",       SOL_SOCKET,    SO_RCVTIMEO,     0,                 OPT_INT},
 344 #endif
 345   {NULL,0,0,0,0}};
 346
 347
 348
 349 /****************************************************************************
 350 set user socket options
 351 ****************************************************************************/
 352 void set_socket_options(int fd, char *options)
 353 {
 354         char *tok;
 355         if (!options || !*options) return;
 356
 357         options = strdup(options);
 358
 359         if (!options) out_of_memory("set_socket_options");
 360
 361         for (tok=strtok(options, " \t,"); tok; tok=strtok(NULL," \t,")) {
 362                 int ret=0,i;
 363                 int value = 1;
 364                 char *p;
 365                 int got_value = 0;
 366
 367                 if ((p = strchr(tok,'='))) {
 368                         *p = 0;
 369                         value = atoi(p+1);
 370                         got_value = 1;
 371                 }
 372
 373                 for (i=0;socket_options[i].name;i++)
 374                         if (strcmp(socket_options[i].name,tok)==0)
 375                                 break;
 376
 377                 if (!socket_options[i].name) {
 378                         rprintf(FERROR,"Unknown socket option %s\n",tok);
 379                         continue;
 380                 }
 381
 382                 switch (socket_options[i].opttype) {
 383                 case OPT_BOOL:
 384                 case OPT_INT:
 385                         ret = setsockopt(fd,socket_options[i].level,
 386                                          socket_options[i].option,(char *)&value,sizeof(int));
 387                         break;
 388
 389                 case OPT_ON:
 390                         if (got_value)
 391                                 rprintf(FERROR,"syntax error - %s does not take a value\n",tok);
 392
 393                         {
 394                                 int on = socket_options[i].value;
 395                                 ret = setsockopt(fd,socket_options[i].level,
 396                                                  socket_options[i].option,(char *)&on,sizeof(int));
 397                         }
 398                         break;
 399                 }
 400
 401                 if (ret != 0)
 402                         rprintf(FERROR, "failed to set socket option %s: %s\n", tok,
 403                                 strerror(errno));
 404         }
 405
 406         free(options);
 407 }
 408
 409 /****************************************************************************
 410 become a daemon, discarding the controlling terminal
 411 ****************************************************************************/
 412 void become_daemon(void)
 413 {
 414         int i;
 415
 416         if (fork()) {
 417                 _exit(0);
 418         }
 419
 420         /* detach from the terminal */
 421 #ifdef HAVE_SETSID
 422         setsid();
 423 #else
 424 #ifdef TIOCNOTTY
 425         i = open("/dev/tty", O_RDWR);
 426         if (i >= 0) {
 427                 ioctl(i, (int) TIOCNOTTY, (char *)0);
 428                 close(i);
 429         }
 430 #endif /* TIOCNOTTY */
 431 #endif
 432         /* make sure that stdin, stdout an stderr don't stuff things
 433            up (library functions, for example) */
 434         for (i=0;i<3;i++) {
 435                 close(i);
 436                 open("/dev/null", O_RDWR);
 437         }
 438 }
 439
 440 /*******************************************************************
 441  return the IP addr of the client as a string
 442  ******************************************************************/
 443 char *client_addr(int fd)
 444 {
 445         struct sockaddr sa;
 446         struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
 447         socklen_t length = sizeof(sa);
 448         static char addr_buf[100];
 449         static int initialised;
 450
 451         if (initialised) return addr_buf;
 452
 453         initialised = 1;
 454
 455         if (getpeername(fd, &sa, &length)) {
 456                 exit_cleanup(RERR_SOCKETIO);
 457         }
 458
 459         strlcpy(addr_buf,(char *)inet_ntoa(sockin->sin_addr), sizeof(addr_buf));
 460         return addr_buf;
 461 }
 462
 463
 464 /*******************************************************************
 465  return the DNS name of the client
 466  ******************************************************************/
 467 char *client_name(int fd)
 468 {
 469         struct sockaddr sa;
 470         struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
 471         socklen_t length = sizeof(sa);
 472         static char name_buf[100];
 473         struct hostent *hp;
 474         char **p;
 475         char *def = "UNKNOWN";
 476         static int initialised;
 477
 478         if (initialised) return name_buf;
 479
 480         initialised = 1;
 481
 482         strcpy(name_buf,def);
 483
 484         if (getpeername(fd, &sa, &length)) {
 485                 exit_cleanup(RERR_SOCKETIO);
 486         }
 487
 488         /* Look up the remote host name. */
 489         if ((hp = gethostbyaddr((char *) &sockin->sin_addr,
 490                                 sizeof(sockin->sin_addr),
 491                                 AF_INET))) {
 492                 strlcpy(name_buf,(char *)hp->h_name,sizeof(name_buf));
 493         }
 494
 495
 496         /* do a forward lookup as well to prevent spoofing */
 497         hp = gethostbyname(name_buf);
 498         if (!hp) {
 499                 strcpy (name_buf,def);
 500                 rprintf (FERROR, "reverse name lookup for \"%s\" failed\n",
 501                         name_buf);
 502         } else {
 503                 for (p=hp->h_addr_list;*p;p++) {
 504                         if (memcmp(*p, &sockin->sin_addr, hp->h_length) == 0) {
 505                                 break;
 506                         }
 507                 }
 508                 if (!*p) {
 509                         strcpy(name_buf,def);
 510                         rprintf(FERROR,"reverse name lookup mismatch - spoofed address?\n");
 511                 }
 512         }
 513
 514         return name_buf;
 515 }
 516
 517 /**
 518    Convert a string to an IP address. The string can be a name or
 519    dotted decimal number.
 520
 521    Returns a pointer to a static in_addr struct -- if you call this
 522    more than once then you should copy it.
 523 */
 524 struct in_addr *ip_address(const char *str)
 525 {
 526         static struct in_addr ret;
 527         struct hostent *hp;
 528
 529         if (!str) {
 530                 rprintf (FERROR, "ip_address received NULL name\n");
 531                 return NULL;
 532         }
 533
 534         /* try as an IP address */
 535         if (inet_aton(str, &ret) != 0) {
 536                 return &ret;
 537         }
 538
 539         /* otherwise assume it's a network name of some sort and use
 540            gethostbyname */
 541         if ((hp = gethostbyname (str)) == 0) {
 542                 rprintf(FERROR, "gethostbyname failed for \"%s\": unknown host?\n",str);
 543                 return NULL;
 544         }
 545
 546         if (hp->h_addr == NULL) {
 547                 rprintf(FERROR, "gethostbyname: host address is invalid for host \"%s\"\n",str);
 548                 return NULL;
 549         }
 550
 551         if (hp->h_length > sizeof ret) {
 552                 rprintf(FERROR, "gethostbyname: host address for \"%s\" is too large\n",
 553                         str);
 554                 return NULL;
 555         }
 556
 557         if (hp->h_addrtype != AF_INET) {
 558                 rprintf (FERROR, "gethostname: host address for \"%s\" is not IPv4\n",
 559                          str);
 560                 return NULL;
 561         }
 562
 563         /* This is kind of difficult.  The only field in ret is
 564            s_addr, which is the IP address as a 32-bit int.  On
 565            UNICOS, s_addr is in fact a *bitfield* for reasons best
 566            know to Cray.  This means we can't memcpy in to it.  On the
 567            other hand, h_addr is a char*, so we can't just assign.
 568
 569            Since there's meant to be only one field inside the in_addr
 570            structure we will try just copying over the top and see how
 571            that goes. */
 572         memcpy (&ret, hp->h_addr, hp->h_length);
 573
 574         return &ret;
 575 }