socket.c

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