/* -*- c-file-style: "linux" -*- rsync -- fast file replication program Copyright (C) 1992-2001 by Andrew Tridgell Copyright (C) 2001, 2002 by Martin Pool This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /** * @file socket.c * * Socket functions used in rsync. * * This file is now converted to use the new-style getaddrinfo() * interface, which supports IPv6 but is also supported on recent * IPv4-only machines. On systems that don't have that interface, we * emulate it using the KAME implementation. **/ #include "rsync.h" /** * Establish a proxy connection on an open socket to a web proxy by * using the HTTP CONNECT method. **/ static int establish_proxy_connection(int fd, char *host, int port) { char buffer[1024]; char *cp; snprintf(buffer, sizeof(buffer), "CONNECT %s:%d HTTP/1.0\r\n\r\n", host, port); if (write(fd, buffer, strlen(buffer)) != (int) strlen(buffer)) { rprintf(FERROR, "failed to write to proxy: %s\n", strerror(errno)); return -1; } for (cp = buffer; cp < &buffer[sizeof(buffer) - 1]; cp++) { if (read(fd, cp, 1) != 1) { rprintf(FERROR, "failed to read from proxy: %s\n", strerror(errno)); return -1; } if (*cp == '\n') break; } if (*cp != '\n') cp++; *cp-- = '\0'; if (*cp == '\r') *cp = '\0'; if (strncmp(buffer, "HTTP/", 5) != 0) { rprintf(FERROR, "bad response from proxy - %s\n", buffer); return -1; } for (cp = &buffer[5]; isdigit(* (unsigned char *) cp) || (*cp == '.'); cp++) ; while (*cp == ' ') cp++; if (*cp != '2') { rprintf(FERROR, "bad response from proxy - %s\n", buffer); return -1; } /* throw away the rest of the HTTP header */ while (1) { for (cp = buffer; cp < &buffer[sizeof(buffer) - 1]; cp++) { if (read(fd, cp, 1) != 1) { rprintf(FERROR, "failed to read from proxy: %s\n", strerror(errno)); return -1; } if (*cp == '\n') break; } if ((cp > buffer) && (*cp == '\n')) cp--; if ((cp == buffer) && ((*cp == '\n') || (*cp == '\r'))) break; } return 0; } /** * Try to set the local address for a newly-created socket. Return -1 * if this fails. **/ int try_bind_local(int s, int ai_family, int ai_socktype, const char *bind_address) { int error; struct addrinfo bhints, *bres_all, *r; memset(&bhints, 0, sizeof(bhints)); bhints.ai_family = ai_family; bhints.ai_socktype = ai_socktype; bhints.ai_flags = AI_PASSIVE; if ((error = getaddrinfo(bind_address, NULL, &bhints, &bres_all))) { rprintf(FERROR, RSYNC_NAME ": getaddrinfo %s: %s\n", bind_address, gai_strerror(error)); return -1; } for (r = bres_all; r; r = r->ai_next) { if (bind(s, r->ai_addr, r->ai_addrlen) == -1) continue; freeaddrinfo(bres_all); return s; } /* no error message; there might be some problem that allows * creation of the socket but not binding, perhaps if the * machine has no ipv6 address of this name. */ freeaddrinfo(bres_all); return -1; } /** * Open a socket to a tcp remote host with the specified port . * * Based on code from Warren. Proxy support by Stephen Rothwell. * getaddrinfo() rewrite contributed by KAME.net. * * Now that we support IPv6 we need to look up the remote machine's * address first, using @p af_hint to set a preference for the type * of address. Then depending on whether it has v4 or v6 addresses we * try to open a connection. * * The loop allows for machines with some addresses which may not be * reachable, perhaps because we can't e.g. route ipv6 to that network * but we can get ip4 packets through. * * @param bind_address Local address to use. Normally NULL to bind * the wildcard address. * * @param af_hint Address family, e.g. AF_INET or AF_INET6. **/ int open_socket_out(char *host, int port, const char *bind_address, int af_hint) { int type = SOCK_STREAM; int error; int s; struct addrinfo hints, *res0, *res; char portbuf[10]; char *h; int proxied = 0; char buffer[1024]; char *cp; /* if we have a RSYNC_PROXY env variable then redirect our * connetcion via a web proxy at the given address. The format * is hostname:port */ h = getenv("RSYNC_PROXY"); proxied = (h != NULL) && (*h != '\0'); if (proxied) { strlcpy(buffer, h, sizeof(buffer)); cp = strchr(buffer, ':'); if (cp == NULL) { rprintf(FERROR, "invalid proxy specification: should be HOST:PORT\n"); return -1; } *cp++ = '\0'; strcpy(portbuf, cp); h = buffer; if (verbose >= 2) { rprintf(FINFO, "connection via http proxy %s port %s\n", h, portbuf); } } else { snprintf(portbuf, sizeof(portbuf), "%d", port); h = host; } memset(&hints, 0, sizeof(hints)); hints.ai_family = af_hint; hints.ai_socktype = type; error = getaddrinfo(h, portbuf, &hints, &res0); if (error) { rprintf(FERROR, RSYNC_NAME ": getaddrinfo: %s %s: %s\n", h, portbuf, gai_strerror(error)); return -1; } s = -1; /* Try to connect to all addresses for this machine until we get * through. It might e.g. be multi-homed, or have both IPv4 and IPv6 * addresses. We need to create a socket for each record, since the * address record tells us what protocol to use to try to connect. */ for (res = res0; res; res = res->ai_next) { s = socket(res->ai_family, res->ai_socktype, res->ai_protocol); if (s < 0) continue; if (bind_address) if (try_bind_local(s, res->ai_family, type, bind_address) == -1) { close(s); s = -1; continue; } if (connect(s, res->ai_addr, res->ai_addrlen) < 0) { close(s); s = -1; continue; } if (proxied && establish_proxy_connection(s, host, port) != 0) { close(s); s = -1; continue; } else break; } freeaddrinfo(res0); if (s < 0) { rprintf(FERROR, RSYNC_NAME ": failed to connect to %s: %s\n", h, strerror(errno)); return -1; } return s; } /** * Open an outgoing socket, but allow for it to be intercepted by * $RSYNC_CONNECT_PROG, which will execute a program across a TCP * socketpair rather than really opening a socket. * * We use this primarily in testing to detect TCP flow bugs, but not * cause security problems by really opening remote connections. * * This is based on the Samba LIBSMB_PROG feature. * * @param bind_address Local address to use. Normally NULL to get the stack default. **/ int open_socket_out_wrapped (char *host, int port, const char *bind_address, int af_hint) { char *prog; if ((prog = getenv ("RSYNC_CONNECT_PROG")) != NULL) return sock_exec (prog); else return open_socket_out (host, port, bind_address, af_hint); } /** * Open a socket of the specified type, port and address for incoming data * * Try to be better about handling the results of getaddrinfo(): when * opening an inbound socket, we might get several address results, * e.g. for the machine's ipv4 and ipv6 name. * * If binding a wildcard, then any one of them should do. If an address * was specified but it's insufficiently specific then that's not our * fault. * * However, some of the advertized addresses may not work because e.g. we * don't have IPv6 support in the kernel. In that case go on and try all * addresses until one succeeds. * * @param bind_address Local address to bind, or NULL to allow it to * default. **/ static int open_socket_in(int type, int port, const char *bind_address, int af_hint) { int one=1; int s; struct addrinfo hints, *all_ai, *resp; char portbuf[10]; int error; memset(&hints, 0, sizeof(hints)); hints.ai_family = af_hint; hints.ai_socktype = type; hints.ai_flags = AI_PASSIVE; snprintf(portbuf, sizeof(portbuf), "%d", port); error = getaddrinfo(bind_address, portbuf, &hints, &all_ai); if (error) { rprintf(FERROR, RSYNC_NAME ": getaddrinfo: bind address %s: %s\n", bind_address, gai_strerror(error)); return -1; } /* We may not be able to create the socket, if for example the * machine knows about IPv6 in the C library, but not in the * kernel. */ for (resp = all_ai; resp; resp = resp->ai_next) { s = socket(resp->ai_family, resp->ai_socktype, resp->ai_protocol); if (s == -1) /* See if there's another address that will work... */ continue; setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&one, sizeof one); /* now we've got a socket - we need to bind it */ if (bind(s, all_ai->ai_addr, all_ai->ai_addrlen) < 0) { /* Nope, try another */ close(s); continue; } freeaddrinfo(all_ai); return s; } rprintf(FERROR, RSYNC_NAME ": open inbound socket on port %d failed: " "%s\n", port, strerror(errno)); freeaddrinfo(all_ai); return -1; } /* * Determine if a file descriptor is in fact a socket */ int is_a_socket(int fd) { int v; socklen_t l; l = sizeof(int); /* Parameters to getsockopt, setsockopt etc are very * unstandardized across platforms, so don't be surprised if * there are compiler warnings on e.g. SCO OpenSwerver or AIX. * It seems they all eventually get the right idea. * * Debian says: ``The fifth argument of getsockopt and * setsockopt is in reality an int [*] (and this is what BSD * 4.* and libc4 and libc5 have). Some POSIX confusion * resulted in the present socklen_t. The draft standard has * not been adopted yet, but glibc2 already follows it and * also has socklen_t [*]. See also accept(2).'' * * We now return to your regularly scheduled programming. */ return(getsockopt(fd, SOL_SOCKET, SO_TYPE, (char *)&v, &l) == 0); } static RETSIGTYPE sigchld_handler(UNUSED(int val)) { signal(SIGCHLD, sigchld_handler); #ifdef WNOHANG while (waitpid(-1, NULL, WNOHANG) > 0) {} #endif } void start_accept_loop(int port, int (*fn)(int, int)) { int s; extern char *bind_address; extern int default_af_hint; /* open an incoming socket */ s = open_socket_in(SOCK_STREAM, port, bind_address, default_af_hint); if (s == -1) exit_cleanup(RERR_SOCKETIO); /* ready to listen */ if (listen(s, 5) == -1) { close(s); exit_cleanup(RERR_SOCKETIO); } /* now accept incoming connections - forking a new process for each incoming connection */ while (1) { fd_set fds; pid_t pid; int fd; struct sockaddr_storage addr; socklen_t addrlen = sizeof addr; /* close log file before the potentially very long select so file can be trimmed by another process instead of growing forever */ log_close(); FD_ZERO(&fds); FD_SET(s, &fds); if (select(s+1, &fds, NULL, NULL, NULL) != 1) { continue; } if(!FD_ISSET(s, &fds)) continue; fd = accept(s,(struct sockaddr *)&addr,&addrlen); if (fd == -1) continue; signal(SIGCHLD, sigchld_handler); if ((pid = fork()) == 0) { int ret; close(s); /* open log file in child before possibly giving up privileges */ log_open(); ret = fn(fd, fd); close_all(); _exit(ret); } else if (pid < 0) { rprintf(FERROR, RSYNC_NAME ": could not create child server process: %s\n", strerror(errno)); close(fd); /* This might have happened because we're * overloaded. Sleep briefly before trying to * accept again. */ sleep(2); } else { /* Parent doesn't need this fd anymore. */ close(fd); } } } enum SOCK_OPT_TYPES {OPT_BOOL,OPT_INT,OPT_ON}; struct { char *name; int level; int option; int value; int opttype; } socket_options[] = { {"SO_KEEPALIVE", SOL_SOCKET, SO_KEEPALIVE, 0, OPT_BOOL}, {"SO_REUSEADDR", SOL_SOCKET, SO_REUSEADDR, 0, OPT_BOOL}, {"SO_BROADCAST", SOL_SOCKET, SO_BROADCAST, 0, OPT_BOOL}, #ifdef TCP_NODELAY {"TCP_NODELAY", IPPROTO_TCP, TCP_NODELAY, 0, OPT_BOOL}, #endif #ifdef IPTOS_LOWDELAY {"IPTOS_LOWDELAY", IPPROTO_IP, IP_TOS, IPTOS_LOWDELAY, OPT_ON}, #endif #ifdef IPTOS_THROUGHPUT {"IPTOS_THROUGHPUT", IPPROTO_IP, IP_TOS, IPTOS_THROUGHPUT, OPT_ON}, #endif #ifdef SO_SNDBUF {"SO_SNDBUF", SOL_SOCKET, SO_SNDBUF, 0, OPT_INT}, #endif #ifdef SO_RCVBUF {"SO_RCVBUF", SOL_SOCKET, SO_RCVBUF, 0, OPT_INT}, #endif #ifdef SO_SNDLOWAT {"SO_SNDLOWAT", SOL_SOCKET, SO_SNDLOWAT, 0, OPT_INT}, #endif #ifdef SO_RCVLOWAT {"SO_RCVLOWAT", SOL_SOCKET, SO_RCVLOWAT, 0, OPT_INT}, #endif #ifdef SO_SNDTIMEO {"SO_SNDTIMEO", SOL_SOCKET, SO_SNDTIMEO, 0, OPT_INT}, #endif #ifdef SO_RCVTIMEO {"SO_RCVTIMEO", SOL_SOCKET, SO_RCVTIMEO, 0, OPT_INT}, #endif {NULL,0,0,0,0}}; /** * Set user socket options **/ void set_socket_options(int fd, char *options) { char *tok; if (!options || !*options) return; options = strdup(options); if (!options) out_of_memory("set_socket_options"); for (tok=strtok(options, " \t,"); tok; tok=strtok(NULL," \t,")) { int ret=0,i; int value = 1; char *p; int got_value = 0; if ((p = strchr(tok,'='))) { *p = 0; value = atoi(p+1); got_value = 1; } for (i=0;socket_options[i].name;i++) if (strcmp(socket_options[i].name,tok)==0) break; if (!socket_options[i].name) { rprintf(FERROR,"Unknown socket option %s\n",tok); continue; } switch (socket_options[i].opttype) { case OPT_BOOL: case OPT_INT: ret = setsockopt(fd,socket_options[i].level, socket_options[i].option,(char *)&value,sizeof(int)); break; case OPT_ON: if (got_value) rprintf(FERROR,"syntax error - %s does not take a value\n",tok); { int on = socket_options[i].value; ret = setsockopt(fd,socket_options[i].level, socket_options[i].option,(char *)&on,sizeof(int)); } break; } if (ret != 0) rprintf(FERROR, "failed to set socket option %s: %s\n", tok, strerror(errno)); } free(options); } /** * Become a daemon, discarding the controlling terminal **/ void become_daemon(void) { int i; if (fork()) { _exit(0); } /* detach from the terminal */ #ifdef HAVE_SETSID setsid(); #else #ifdef TIOCNOTTY i = open("/dev/tty", O_RDWR); if (i >= 0) { ioctl(i, (int) TIOCNOTTY, (char *)0); close(i); } #endif /* TIOCNOTTY */ #endif /* make sure that stdin, stdout an stderr don't stuff things up (library functions, for example) */ for (i=0;i<3;i++) { close(i); open("/dev/null", O_RDWR); } } /** * This is like socketpair but uses tcp. It is used by the Samba * regression test code. * * The function guarantees that nobody else can attach to the socket, * or if they do that this function fails and the socket gets closed * returns 0 on success, -1 on failure the resulting file descriptors * are symmetrical. **/ static int socketpair_tcp(int fd[2]) { int listener; struct sockaddr_in sock; struct sockaddr_in sock2; socklen_t socklen = sizeof(sock); int connect_done = 0; fd[0] = fd[1] = listener = -1; memset(&sock, 0, sizeof(sock)); if ((listener = socket(PF_INET, SOCK_STREAM, 0)) == -1) goto failed; memset(&sock2, 0, sizeof(sock2)); #ifdef HAVE_SOCKADDR_LEN sock2.sin_len = sizeof(sock2); #endif sock2.sin_family = PF_INET; bind(listener, (struct sockaddr *)&sock2, sizeof(sock2)); if (listen(listener, 1) != 0) goto failed; if (getsockname(listener, (struct sockaddr *)&sock, &socklen) != 0) goto failed; if ((fd[1] = socket(PF_INET, SOCK_STREAM, 0)) == -1) goto failed; set_nonblocking(fd[1]); sock.sin_addr.s_addr = htonl(INADDR_LOOPBACK); if (connect(fd[1],(struct sockaddr *)&sock,sizeof(sock)) == -1) { if (errno != EINPROGRESS) goto failed; } else { connect_done = 1; } if ((fd[0] = accept(listener, (struct sockaddr *)&sock, &socklen)) == -1) goto failed; close(listener); if (connect_done == 0) { if (connect(fd[1],(struct sockaddr *)&sock,sizeof(sock)) != 0 && errno != EISCONN) goto failed; } set_blocking (fd[1]); /* all OK! */ return 0; failed: if (fd[0] != -1) close(fd[0]); if (fd[1] != -1) close(fd[1]); if (listener != -1) close(listener); return -1; } /** * Run a program on a local tcp socket, so that we can talk to it's * stdin and stdout. This is used to fake a connection to a daemon * for testing -- not for the normal case of running SSH. * * @return a socket which is attached to a subprocess running * "prog". stdin and stdout are attached. stderr is left attached to * the original stderr **/ int sock_exec(const char *prog) { int fd[2]; if (socketpair_tcp(fd) != 0) { rprintf (FERROR, RSYNC_NAME ": socketpair_tcp failed (%s)\n", strerror(errno)); return -1; } if (fork() == 0) { close(fd[0]); close(0); close(1); dup(fd[1]); dup(fd[1]); if (verbose > 3) { /* Can't use rprintf because we've forked. */ fprintf (stderr, RSYNC_NAME ": execute socket program \"%s\"\n", prog); } exit (system (prog)); } close (fd[1]); return fd[0]; }