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, struct in_addr *address)
  93 {
  94         int type = SOCK_STREAM;
  95         struct sockaddr_in sock_out;
  96         struct sockaddr_in sock;
  97         int res;
  98         struct hostent *hp;
  99         char *h;
 100         unsigned p;
 101         int proxied = 0;
 102         char buffer[1024];
 103         char *cp;
 104
 105         /* if we have a RSYNC_PROXY env variable then redirect our connetcion via a web proxy
 106            at the given address. The format is hostname:port */
 107         h = getenv("RSYNC_PROXY");
 108         proxied = (h != NULL) && (*h != '\0');
 109
 110         if (proxied) {
 111                 strlcpy(buffer, h, sizeof(buffer));
 112                 cp = strchr(buffer, ':');
 113                 if (cp == NULL) {
 114                         rprintf(FERROR, "invalid proxy specification\n");
 115                         return -1;
 116                 }
 117                 *cp++ = '\0';
 118                 p = atoi(cp);
 119                 h = buffer;
 120         } else {
 121                 h = host;
 122                 p = port;
 123         }
 124
 125         res = socket(PF_INET, type, 0);
 126         if (res == -1) {
 127                 return -1;
 128         }
 129
 130         hp = gethostbyname(h);
 131         if (!hp) {
 132                 rprintf(FERROR,"unknown host: %s\n", h);
 133                 close(res);
 134                 return -1;
 135         }
 136
 137         memcpy(&sock_out.sin_addr, hp->h_addr, hp->h_length);
 138         sock_out.sin_port = htons(p);
 139         sock_out.sin_family = PF_INET;
 140
 141         if (address) {
 142                 sock.sin_addr = *address;
 143                 sock.sin_port = 0;
 144                 sock.sin_family = hp->h_addrtype;
 145                 bind(res, (struct sockaddr * ) &sock,sizeof(sock));
 146         }
 147
 148         if (connect(res,(struct sockaddr *)&sock_out,sizeof(sock_out))) {
 149                 rprintf(FERROR,"failed to connect to %s - %s\n", h, strerror(errno));
 150                 close(res);
 151                 return -1;
 152         }
 153
 154         if (proxied && establish_proxy_connection(res, host, port) != 0) {
 155                 close(res);
 156                 return -1;
 157         }
 158
 159         return res;
 160 }
 161
 162
 163 /****************************************************************************
 164 open a socket of the specified type, port and address for incoming data
 165 ****************************************************************************/
 166 static int open_socket_in(int type, int port, struct in_addr *address)
 167 {
 168         struct hostent *hp;
 169         struct sockaddr_in sock;
 170         char host_name[MAXHOSTNAMELEN];
 171         int res;
 172         int one=1;
 173
 174         /* get my host name */
 175         if (gethostname(host_name, sizeof(host_name)) == -1) {
 176                 rprintf(FERROR,"gethostname failed\n");
 177                 return -1;
 178         }
 179
 180         /* get host info */
 181         if ((hp = gethostbyname(host_name)) == 0) {
 182                 rprintf(FERROR,"gethostbyname: Unknown host %s\n",host_name);
 183                 return -1;
 184         }
 185
 186         memset((char *)&sock,0,sizeof(sock));
 187         memcpy((char *)&sock.sin_addr,(char *)hp->h_addr, hp->h_length);
 188         sock.sin_port = htons(port);
 189         sock.sin_family = hp->h_addrtype;
 190         if (address) {
 191                 sock.sin_addr = *address;
 192         } else {
 193                 sock.sin_addr.s_addr = INADDR_ANY;
 194         }
 195         res = socket(hp->h_addrtype, type, 0);
 196         if (res == -1) {
 197                 rprintf(FERROR,"socket failed\n");
 198                 return -1;
 199         }
 200
 201         setsockopt(res,SOL_SOCKET,SO_REUSEADDR,(char *)&one,sizeof(one));
 202
 203         /* now we've got a socket - we need to bind it */
 204         if (bind(res, (struct sockaddr * ) &sock,sizeof(sock)) == -1) {
 205                 rprintf(FERROR,"bind failed on port %d\n", port);
 206                 close(res);
 207                 return -1;
 208         }
 209
 210         return res;
 211 }
 212
 213
 214 /****************************************************************************
 215 determine if a file descriptor is in fact a socket
 216 ****************************************************************************/
 217 int is_a_socket(int fd)
 218 {
 219         int v,l;
 220         l = sizeof(int);
 221         return(getsockopt(fd, SOL_SOCKET, SO_TYPE, (char *)&v, &l) == 0);
 222 }
 223
 224
 225 void start_accept_loop(int port, int (*fn)(int ))
 226 {
 227         int s;
 228         extern struct in_addr socket_address;
 229
 230         /* open an incoming socket */
 231         s = open_socket_in(SOCK_STREAM, port, &socket_address);
 232         if (s == -1)
 233                 exit_cleanup(RERR_SOCKETIO);
 234
 235         /* ready to listen */
 236         if (listen(s, 5) == -1) {
 237                 close(s);
 238                 exit_cleanup(RERR_SOCKETIO);
 239         }
 240
 241
 242         /* now accept incoming connections - forking a new process
 243            for each incoming connection */
 244         while (1) {
 245                 fd_set fds;
 246                 int fd;
 247                 struct sockaddr addr;
 248                 int in_addrlen = sizeof(addr);
 249
 250                 FD_ZERO(&fds);
 251                 FD_SET(s, &fds);
 252
 253                 if (select(s+1, &fds, NULL, NULL, NULL) != 1) {
 254                         continue;
 255                 }
 256
 257                 if(!FD_ISSET(s, &fds)) continue;
 258
 259                 fd = accept(s,&addr,&in_addrlen);
 260
 261                 if (fd == -1) continue;
 262
 263                 signal(SIGCHLD, SIG_IGN);
 264
 265                 /* we shouldn't have any children left hanging around
 266                    but I have had reports that on Digital Unix zombies
 267                    are produced, so this ensures that they are reaped */
 268 #ifdef WNOHANG
 269                 while (waitpid(-1, NULL, WNOHANG) > 0);
 270 #endif
 271
 272                 if (fork()==0) {
 273                         close(s);
 274
 275                         _exit(fn(fd));
 276                 }
 277
 278                 close(fd);
 279         }
 280 }
 281
 282
 283 enum SOCK_OPT_TYPES {OPT_BOOL,OPT_INT,OPT_ON};
 284
 285 struct
 286 {
 287   char *name;
 288   int level;
 289   int option;
 290   int value;
 291   int opttype;
 292 } socket_options[] = {
 293   {"SO_KEEPALIVE",      SOL_SOCKET,    SO_KEEPALIVE,    0,                 OPT_BOOL},
 294   {"SO_REUSEADDR",      SOL_SOCKET,    SO_REUSEADDR,    0,                 OPT_BOOL},
 295   {"SO_BROADCAST",      SOL_SOCKET,    SO_BROADCAST,    0,                 OPT_BOOL},
 296 #ifdef TCP_NODELAY
 297   {"TCP_NODELAY",       IPPROTO_TCP,   TCP_NODELAY,     0,                 OPT_BOOL},
 298 #endif
 299 #ifdef IPTOS_LOWDELAY
 300   {"IPTOS_LOWDELAY",    IPPROTO_IP,    IP_TOS,          IPTOS_LOWDELAY,    OPT_ON},
 301 #endif
 302 #ifdef IPTOS_THROUGHPUT
 303   {"IPTOS_THROUGHPUT",  IPPROTO_IP,    IP_TOS,          IPTOS_THROUGHPUT,  OPT_ON},
 304 #endif
 305 #ifdef SO_SNDBUF
 306   {"SO_SNDBUF",         SOL_SOCKET,    SO_SNDBUF,       0,                 OPT_INT},
 307 #endif
 308 #ifdef SO_RCVBUF
 309   {"SO_RCVBUF",         SOL_SOCKET,    SO_RCVBUF,       0,                 OPT_INT},
 310 #endif
 311 #ifdef SO_SNDLOWAT
 312   {"SO_SNDLOWAT",       SOL_SOCKET,    SO_SNDLOWAT,     0,                 OPT_INT},
 313 #endif
 314 #ifdef SO_RCVLOWAT
 315   {"SO_RCVLOWAT",       SOL_SOCKET,    SO_RCVLOWAT,     0,                 OPT_INT},
 316 #endif
 317 #ifdef SO_SNDTIMEO
 318   {"SO_SNDTIMEO",       SOL_SOCKET,    SO_SNDTIMEO,     0,                 OPT_INT},
 319 #endif
 320 #ifdef SO_RCVTIMEO
 321   {"SO_RCVTIMEO",       SOL_SOCKET,    SO_RCVTIMEO,     0,                 OPT_INT},
 322 #endif
 323   {NULL,0,0,0,0}};
 324
 325
 326
 327 /****************************************************************************
 328 set user socket options
 329 ****************************************************************************/
 330 void set_socket_options(int fd, char *options)
 331 {
 332         char *tok;
 333         if (!options || !*options) return;
 334
 335         options = strdup(options);
 336
 337         if (!options) out_of_memory("set_socket_options");
 338
 339         for (tok=strtok(options, " \t,"); tok; tok=strtok(NULL," \t,")) {
 340                 int ret=0,i;
 341                 int value = 1;
 342                 char *p;
 343                 int got_value = 0;
 344
 345                 if ((p = strchr(tok,'='))) {
 346                         *p = 0;
 347                         value = atoi(p+1);
 348                         got_value = 1;
 349                 }
 350
 351                 for (i=0;socket_options[i].name;i++)
 352                         if (strcmp(socket_options[i].name,tok)==0)
 353                                 break;
 354
 355                 if (!socket_options[i].name) {
 356                         rprintf(FERROR,"Unknown socket option %s\n",tok);
 357                         continue;
 358                 }
 359
 360                 switch (socket_options[i].opttype) {
 361                 case OPT_BOOL:
 362                 case OPT_INT:
 363                         ret = setsockopt(fd,socket_options[i].level,
 364                                          socket_options[i].option,(char *)&value,sizeof(int));
 365                         break;
 366
 367                 case OPT_ON:
 368                         if (got_value)
 369                                 rprintf(FERROR,"syntax error - %s does not take a value\n",tok);
 370
 371                         {
 372                                 int on = socket_options[i].value;
 373                                 ret = setsockopt(fd,socket_options[i].level,
 374                                                  socket_options[i].option,(char *)&on,sizeof(int));
 375                         }
 376                         break;
 377                 }
 378
 379                 if (ret != 0)
 380                         rprintf(FERROR,"Failed to set socket option %s\n",tok);
 381         }
 382
 383         free(options);
 384 }
 385
 386 /****************************************************************************
 387 become a daemon, discarding the controlling terminal
 388 ****************************************************************************/
 389 void become_daemon(void)
 390 {
 391         int i;
 392
 393         if (fork()) {
 394                 _exit(0);
 395         }
 396
 397         /* detach from the terminal */
 398 #ifdef HAVE_SETSID
 399         setsid();
 400 #else
 401 #ifdef TIOCNOTTY
 402         i = open("/dev/tty", O_RDWR);
 403         if (i >= 0) {
 404                 ioctl(i, (int) TIOCNOTTY, (char *)0);
 405                 close(i);
 406         }
 407 #endif /* TIOCNOTTY */
 408 #endif
 409         /* make sure that stdin, stdout an stderr don't stuff things
 410            up (library functions, for example) */
 411         for (i=0;i<3;i++) {
 412                 close(i);
 413                 open("/dev/null", O_RDWR);
 414         }
 415 }
 416
 417 /*******************************************************************
 418  return the IP addr of the client as a string
 419  ******************************************************************/
 420 char *client_addr(int fd)
 421 {
 422         struct sockaddr sa;
 423         struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
 424         int     length = sizeof(sa);
 425         static char addr_buf[100];
 426         static int initialised;
 427
 428         if (initialised) return addr_buf;
 429
 430         initialised = 1;
 431
 432         if (getpeername(fd, &sa, &length)) {
 433                 exit_cleanup(RERR_SOCKETIO);
 434         }
 435
 436         strlcpy(addr_buf,(char *)inet_ntoa(sockin->sin_addr), sizeof(addr_buf));
 437         return addr_buf;
 438 }
 439
 440
 441 /*******************************************************************
 442  return the DNS name of the client
 443  ******************************************************************/
 444 char *client_name(int fd)
 445 {
 446         struct sockaddr sa;
 447         struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
 448         int     length = sizeof(sa);
 449         static char name_buf[100];
 450         struct hostent *hp;
 451         char **p;
 452         char *def = "UNKNOWN";
 453         static int initialised;
 454
 455         if (initialised) return name_buf;
 456
 457         initialised = 1;
 458
 459         strcpy(name_buf,def);
 460
 461         if (getpeername(fd, &sa, &length)) {
 462                 exit_cleanup(RERR_SOCKETIO);
 463         }
 464
 465         /* Look up the remote host name. */
 466         if ((hp = gethostbyaddr((char *) &sockin->sin_addr,
 467                                 sizeof(sockin->sin_addr),
 468                                 AF_INET))) {
 469                 strlcpy(name_buf,(char *)hp->h_name,sizeof(name_buf));
 470         }
 471
 472
 473         /* do a forward lookup as well to prevent spoofing */
 474         hp = gethostbyname(name_buf);
 475         if (!hp) {
 476                 strcpy(name_buf,def);
 477                 rprintf(FERROR,"reverse name lookup failed\n");
 478         } else {
 479                 for (p=hp->h_addr_list;*p;p++) {
 480                         if (memcmp(*p, &sockin->sin_addr, hp->h_length) == 0) {
 481                                 break;
 482                         }
 483                 }
 484                 if (!*p) {
 485                         strcpy(name_buf,def);
 486                         rprintf(FERROR,"reverse name lookup mismatch - spoofed address?\n");
 487                 }
 488         }
 489
 490         return name_buf;
 491 }
 492
 493 /*******************************************************************
 494 convert a string to an IP address. The string can be a name or
 495 dotted decimal number
 496   ******************************************************************/
 497 struct in_addr *ip_address(const char *str)
 498 {
 499         static struct in_addr ret;
 500         struct hostent *hp;
 501
 502         /* try as an IP address */
 503         if (inet_aton(str, &ret) != 0) {
 504                 return &ret;
 505         }
 506
 507         /* otherwise assume it's a network name of some sort and use
 508            gethostbyname */
 509         if ((hp = gethostbyname(str)) == 0) {
 510                 rprintf(FERROR, "gethostbyname: Unknown host. %s\n",str);
 511                 return NULL;
 512         }
 513
 514         if (hp->h_addr == NULL) {
 515                 rprintf(FERROR, "gethostbyname: host address is invalid for host %s\n",str);
 516                 return NULL;
 517         }
 518
 519         if (hp->h_length > sizeof(ret)) {
 520                 rprintf(FERROR, "gethostbyname: host address is too large\n");
 521                 return NULL;
 522         }
 523
 524         memcpy(&ret.s_addr, hp->h_addr, hp->h_length);
 525
 526         return(&ret);
 527 }