socket.c

Rsync 3.0.5 source code

/*
 * Socket functions used in rsync.
 *
 * Copyright (C) 1992-2001 Andrew Tridgell <[e-mail]>
 * Copyright (C) 2001, 2002 Martin Pool <[e-mail]>
 * Copyright (C) 2003-2008 Wayne Davison
 *
 * 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 3 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, visit the http://fsf.org website.
 */

/* 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"
#include "ifuncs.h"
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>

extern char *bind_address;
extern char *sockopts;
extern int default_af_hint;
extern int connect_timeout;

#ifdef HAVE_SIGACTION
static struct sigaction sigact;
#endif

/**
 * Establish a proxy connection on an open socket to a web proxy by
 * using the CONNECT method. If proxy_user and proxy_pass are not NULL,
 * they are used to authenticate to the proxy using the "Basic"
 * proxy-authorization protocol
 **/
static int establish_proxy_connection(int fd, char *host, int port,
				      char *proxy_user, char *proxy_pass)
{
	char *cp, buffer[1024];
	char *authhdr, authbuf[1024];
	int len;

	if (proxy_user && proxy_pass) {
		stringjoin(buffer, sizeof buffer,
			 proxy_user, ":", proxy_pass, NULL);
		len = strlen(buffer);

		if ((len*8 + 5) / 6 >= (int)sizeof authbuf - 3) {
			rprintf(FERROR,
				"authentication information is too long\n");
			return -1;
		}

		base64_encode(buffer, len, authbuf, 1);
		authhdr = "\r\nProxy-Authorization: Basic ";
	} else {
		*authbuf = '\0';
		authhdr = "";
	}

	snprintf(buffer, sizeof buffer, "CONNECT %s:%d HTTP/1.0%s%s\r\n\r\n",
		 host, port, authhdr, authbuf);
	len = strlen(buffer);
	if (write(fd, buffer, len) != len) {
		rsyserr(FERROR, errno, "failed to write to proxy");
		return -1;
	}

	for (cp = buffer; cp < &buffer[sizeof buffer - 1]; cp++) {
		if (read(fd, cp, 1) != 1) {
			rsyserr(FERROR, errno, "failed to read from proxy");
			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(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) {
				rsyserr(FERROR, errno,
					"failed to read from proxy");
				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_addr)
{
	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_addr, NULL, &bhints, &bres_all))) {
		rprintf(FERROR, RSYNC_NAME ": getaddrinfo %s: %s\n",
			bind_addr, 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;
}

/* connect() timeout handler based on alarm() */
static RETSIGTYPE contimeout_handler(UNUSED(int val))
{
	connect_timeout = -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_addr 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_addr,
		    int af_hint)
{
	int type = SOCK_STREAM;
	int error, s;
	struct addrinfo hints, *res0, *res;
	char portbuf[10];
	char *h, *cp;
	int proxied = 0;
	char buffer[1024];
	char *proxy_user = NULL, *proxy_pass = NULL;

	/* if we have a RSYNC_PROXY env variable then redirect our
	 * connetcion via a web proxy at the given address. */
	h = getenv("RSYNC_PROXY");
	proxied = h != NULL && *h != '\0';

	if (proxied) {
		strlcpy(buffer, h, sizeof buffer);

		/* Is the USER:PASS@ prefix present? */
		if ((cp = strrchr(buffer, '@')) != NULL) {
			*cp++ = '\0';
			/* The remainder is the HOST:PORT part. */
			h = cp;

			if ((cp = strchr(buffer, ':')) == NULL) {
				rprintf(FERROR,
					"invalid proxy specification: should be USER:PASS@HOST:PORT\n");
				return -1;
			}
			*cp++ = '\0';

			proxy_user = buffer;
			proxy_pass = cp;
		} else {
			/* The whole buffer is the HOST:PORT part. */
			h = buffer;
		}

		if ((cp = strchr(h, ':')) == NULL) {
			rprintf(FERROR,
				"invalid proxy specification: should be HOST:PORT\n");
			return -1;
		}
		*cp++ = '\0';
		strlcpy(portbuf, cp, sizeof portbuf);
		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_addr
		 && try_bind_local(s, res->ai_family, type,
				   bind_addr) == -1) {
			close(s);
			s = -1;
			continue;
		}
		if (connect_timeout > 0) {
			SIGACTION(SIGALRM, contimeout_handler);
			alarm(connect_timeout);
		}

		set_socket_options(s, sockopts);
		while (connect(s, res->ai_addr, res->ai_addrlen) < 0) {
			if (connect_timeout < 0)
				exit_cleanup(RERR_CONTIMEOUT);
			if (errno == EINTR)
				continue;
			close(s);
			s = -1;
			break;
		}

		if (connect_timeout > 0)
			alarm(0);

		if (s < 0)
			continue;

		if (proxied
		 && establish_proxy_connection(s, host, port,
					       proxy_user, proxy_pass) != 0) {
			close(s);
			s = -1;
			continue;
		}
		break;
	}
	freeaddrinfo(res0);
	if (s < 0) {
		rsyserr(FERROR, errno, "failed to connect to %s", h);
		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_addr Local address to use.  Normally NULL to get the stack default.
 **/
int open_socket_out_wrapped(char *host, int port, const char *bind_addr,
			    int af_hint)
{
	char *prog = getenv("RSYNC_CONNECT_PROG");

	if (prog && strchr(prog, '%')) {
		int hlen = strlen(host);
		int len = strlen(prog) + 1;
		char *f, *t;
		for (f = prog; *f; f++) {
			if (*f != '%')
				continue;
			/* Compute more than enough room. */
			if (f[1] == '%')
				f++;
			else
				len += hlen;
		}
		f = prog;
		if (!(prog = new_array(char, len)))
			out_of_memory("open_socket_out_wrapped");
		for (t = prog; *f; f++) {
			if (*f == '%') {
				switch (*++f) {
				case '%':
					/* Just skips the extra '%'. */
					break;
				case 'H':
					memcpy(t, host, hlen);
					t += hlen;
					continue;
				default:
					f--; /* pass % through */
					break;
				}
			}
			*t++ = *f;
		}
		*t = '\0';
	}

	if (verbose >= 2) {
		rprintf(FINFO, "%sopening tcp connection to %s port %d\n",
			prog ? "Using RSYNC_CONNECT_PROG instead of " : "",
			host, port);
	}
	if (prog)
		return sock_exec(prog);
	return open_socket_out(host, port, bind_addr, af_hint);
}



/**
 * Open one or more sockets for incoming data using the specified type,
 * port, and address.
 *
 * The getaddrinfo() call may return several address results, e.g. for
 * the machine's IPv4 and IPv6 name.
 *
 * We return an array of file-descriptors to the sockets, with a trailing
 * -1 value to indicate the end of the list.
 *
 * @param bind_addr Local address to bind, or NULL to allow it to
 * default.
 **/
static int *open_socket_in(int type, int port, const char *bind_addr,
			   int af_hint)
{
	int one = 1;
	int s, *socks, maxs, i, ecnt;
	struct addrinfo hints, *all_ai, *resp;
	char portbuf[10], **errmsgs;
	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_addr, portbuf, &hints, &all_ai);
	if (error) {
		rprintf(FERROR, RSYNC_NAME ": getaddrinfo: bind address %s: %s\n",
			bind_addr, gai_strerror(error));
		return NULL;
	}

	/* Count max number of sockets we might open. */
	for (maxs = 0, resp = all_ai; resp; resp = resp->ai_next, maxs++) {}

	socks = new_array(int, maxs + 1);
	errmsgs = new_array(char *, maxs);
	if (!socks || !errmsgs)
		out_of_memory("open_socket_in");

	/* 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, i = ecnt = 0; resp; resp = resp->ai_next) {
		s = socket(resp->ai_family, resp->ai_socktype,
			   resp->ai_protocol);

		if (s == -1) {
			int r = asprintf(&errmsgs[ecnt++],
				"socket(%d,%d,%d) failed: %s\n",
				(int)resp->ai_family, (int)resp->ai_socktype,