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socket.c File Reference

Socket functions used in rsync. More...

Go to the source code of this file.

Enumerations
enum	SOCK_OPT_TYPES { OPT_BOOL, OPT_INT, OPT_ON }
Functions
int	establish_proxy_connection (int fd, char *host, int port)
	Establish a proxy connection on an open socket to a web proxy by using the HTTP CONNECT method. More...
int	try_bind_local (int s, int ai_family, int ai_socktype, const char *bind_address)
	Try to set the local address for a newly-created socket. More...
int	open_socket_out (char *host, int port, const char *bind_address, int af_hint)
	Open a socket to a tcp remote host with the specified port . More...
int	open_socket_out_wrapped (char *host, int port, const char *bind_address, int af_hint)
	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. More...
int	open_socket_in (int type, int port, const char *bind_address, int af_hint)
	Open a socket of the specified type, port and address for incoming data. More...
int	is_a_socket (int fd)
void	start_accept_loop (int port, int(*fn)(int))
void	set_socket_options (int fd, char *options)
	Set user socket options. More...
void	become_daemon (void)
	Become a daemon, discarding the controlling terminal. More...
int	socketpair_tcp (int fd[2])
	This is like socketpair but uses tcp. More...
int	sock_exec (const char *prog)
	Run a program on a local tcp socket, so that we can talk to it's stdin and stdout. More...
Variables
struct {
char *   name
int   level
int   option
int   value
int   opttype
}	socket_options []

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Detailed Description

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.

Definition in file socket.c.

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Enumeration Type Documentation

enum SOCK_OPT_TYPES

Enumeration values: OPT_BOOL  OPT_INT  OPT_ON  Definition at line 455 of file socket.c. {OPT_BOOL,OPT_INT,OPT_ON};

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Function Documentation

int establish_proxy_connection (  int    fd, char *    host, int    port )  [static]

Establish a proxy connection on an open socket to a web proxy by using the HTTP CONNECT method. Definition at line 41 of file socket.c. References FERROR, host, rprintf(), and snprintf(). Referenced by open_socket_out(). { 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; }

int try_bind_local (  int    s, int    ai_family, int    ai_socktype, const char *    bind_address )

Try to set the local address for a newly-created socket. Return -1 if this fails. Definition at line 107 of file socket.c. References addrinfo::ai_addr, addrinfo::ai_addrlen, addrinfo::ai_family, addrinfo::ai_flags, addrinfo::ai_next, addrinfo::ai_socktype, bind_address, FERROR, gai_strerror(), and rprintf(). Referenced by open_socket_out(). { 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; }

int open_socket_out (  char *    host, int    port, const char *    bind_address, int    af_hint )

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 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. Parameters: bind_address  Local address to use. Normally NULL to bind the wildcard address. af_hint  Address family, e.g. AF_INET or AF_INET6. Definition at line 159 of file socket.c. References addrinfo::ai_addr, addrinfo::ai_addrlen, addrinfo::ai_family, addrinfo::ai_next, addrinfo::ai_protocol, addrinfo::ai_socktype, bind_address, establish_proxy_connection(), FERROR, FINFO, gai_strerror(), getenv(), host, rprintf(), snprintf(), strlcpy(), and try_bind_local(). Referenced by open_socket_out_wrapped(). { 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; }

int open_socket_out_wrapped (  char *    host, int    port, const char *    bind_address, int    af_hint )

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. Parameters: bind_address  Local address to use. Normally NULL to get the stack default. Definition at line 261 of file socket.c. References bind_address, getenv(), host, open_socket_out(), and sock_exec(). Referenced by start_socket_client(). { char *prog; if ((prog = getenv ("RSYNC_CONNECT_PROG")) != NULL) return sock_exec (prog); else return open_socket_out (host, port, bind_address, af_hint); }

int open_socket_in (  int    type, int    port, const char *    bind_address, int    af_hint )  [static]

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. Parameters: bind_address  Local address to bind, or NULL to allow it to default. Definition at line 295 of file socket.c. References addrinfo::ai_addr, addrinfo::ai_addrlen, addrinfo::ai_family, addrinfo::ai_flags, addrinfo::ai_next, addrinfo::ai_protocol, addrinfo::ai_socktype, bind_address, FERROR, gai_strerror(), rprintf(), and snprintf(). Referenced by start_accept_loop(). { 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; }

int is_a_socket (  int    fd )

Definition at line 354 of file socket.c. Referenced by daemon_main(). { 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); }

void start_accept_loop (  int    port, int(*    fn)(int) )

Definition at line 377 of file socket.c. References bind_address, default_af_hint, FERROR, log_close(), log_open(), open_socket_in(), rprintf(), and waitpid(). Referenced by daemon_main(). { 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, SIG_IGN); /* we shouldn't have any children left hanging around but I have had reports that on Digital Unix zombies are produced, so this ensures that they are reaped */ #ifdef WNOHANG while (waitpid(-1, NULL, WNOHANG) > 0); #endif if ((pid = fork()) == 0) { close(s); /* open log file in child before possibly giving up privileges */ log_open(); _exit(fn(fd)); } 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); } } }

void set_socket_options (  int    fd, char *    options )

Set user socket options. Definition at line 502 of file socket.c. References FERROR, level, name, OPT_BOOL, OPT_INT, OPT_ON, option, out_of_memory(), rprintf(), socket_options, strdup(), and value. Referenced by start_daemon(). { 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); }

void become_daemon (  void    )

Become a daemon, discarding the controlling terminal. Definition at line 562 of file socket.c. Referenced by daemon_main(). { 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); } }

int socketpair_tcp (  int    fd[2] )  [static]

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. Definition at line 600 of file socket.c. References set_blocking(), and set_nonblocking(). Referenced by sock_exec(). { 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; }

int sock_exec (  const char *    prog )

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. Returns: a socket which is attached to a subprocess running "prog". stdin and stdout are attached. stderr is left attached to the original stderr Definition at line 669 of file socket.c. References FERROR, rprintf(), and socketpair_tcp(). Referenced by open_socket_out_wrapped(). { 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]; }

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Variable Documentation

char* name

Definition at line 459 of file socket.c. Referenced by set_socket_options().

int level

Definition at line 460 of file socket.c. Referenced by set_socket_options().

int option

Definition at line 461 of file socket.c. Referenced by set_socket_options().

int value

Definition at line 462 of file socket.c. Referenced by abs_val(), dopr(), fmtint(), fmtstr(), ROUND(), and set_socket_options().

int opttype

Definition at line 463 of file socket.c.

struct { ... } socket_options[]

Referenced by set_socket_options().

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