/* * Socket functions used in rsync. * * Copyright (C) 1992-2001 Andrew Tridgell <tridge@samba.org> * Copyright (C) 2001, 2002 Martin Pool <mbp@samba.org> * Copyright (C) 2003-2020 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 "itypes.h"#include "ifuncs.h"#ifdef HAVE_NETINET_IN_SYSTM_H#include <netinet/in_systm.h>#endif#ifdef HAVE_NETINET_IP_H#include <netinet/ip.h>#endif#include <netinet/tcp.h> extern char *bind_address;extern char *sockopts;extern int default_af_hint;extern int connect_timeout;extern int pid_file_fd; #ifdef HAVE_SIGACTIONstatic struct sigaction sigact;#endif static int sock_exec(const char *prog); #define PROXY_BUF_SIZE 1024 /* 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[PROXY_BUF_SIZE + 1];	char *authhdr, authbuf[PROXY_BUF_SIZE + 1];	int len; 	if (proxy_user && proxy_pass) {		stringjoin(buffer, PROXY_BUF_SIZE,			 proxy_user, ":", proxy_pass, NULL);		len = strlen(buffer); 		if ((len*8 + 5) / 6 >= PROXY_BUF_SIZE - 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 = "";	} 	len = snprintf(buffer, PROXY_BUF_SIZE, "CONNECT %s:%d HTTP/1.0%s%s\r\n\r\n", host, port, authhdr, authbuf);	assert(len > 0 && len < PROXY_BUF_SIZE);	if (write(fd, buffer, len) != len) {		rsyserr(FERROR, errno, "failed to write to proxy");		return -1;	} 	for (cp = buffer; cp < &buffer[PROXY_BUF_SIZE - 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[PROXY_BUF_SIZE - 1]) {		rprintf(FERROR, "proxy response line too long\n");		return -1;	}	*cp = '\0';	if (cp > buffer && cp[-1] == '\r')		cp[-1] = '\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[PROXY_BUF_SIZE]; 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 void 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 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. * * bind_addr: local address to use.  Normally NULL to bind the wildcard address. * * 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, j, addr_cnt, *errnos;	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	 * connection 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 (DEBUG_GTE(CONNECT, 1)) {			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;	} 	for (res = res0, addr_cnt = 0; res; res = res->ai_next, addr_cnt++) {}	errnos = new_array0(int, addr_cnt); 	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, j = 0; res; res = res->ai_next, j++) {		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) {			errnos[j] = errno;			continue;		} 		if (proxied && establish_proxy_connection(s, host, port, proxy_user, proxy_pass) != 0) {			close(s);			s = -1;			continue;		}		if (DEBUG_GTE(CONNECT, 2)) {			char buf[2048];			if ((error = getnameinfo(res->ai_addr, res->ai_addrlen, buf, sizeof buf, NULL, 0, NI_NUMERICHOST)) != 0)				snprintf(buf, sizeof buf, "*getnameinfo failure: %s*", gai_strerror(error));			rprintf(FINFO, "Connected to %s (%s)\n", h, buf);		}		break;	} 	if (s < 0 || DEBUG_GTE(CONNECT, 2)) {		char buf[2048];		for (res = res0, j = 0; res; res = res->ai_next, j++) {			if (errnos[j] == 0)				continue;			if ((error = getnameinfo(res->ai_addr, res->ai_addrlen, buf, sizeof buf, NULL, 0, NI_NUMERICHOST)) != 0)				snprintf(buf, sizeof buf, "*getnameinfo failure: %s*", gai_strerror(error));			rsyserr(FERROR, errnos[j], "failed to connect to %s (%s)", h, buf);		}		if (s < 0)			s = -1;	} 	freeaddrinfo(res0);	free(errnos); 	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. * * 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;		prog = new_array(char, len);		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 (DEBUG_GTE(CONNECT, 1)) {		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. * * 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); 	/* 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,				(int)resp->ai_protocol, strerror(errno));			if (r < 0)				out_of_memory("open_socket_in");			/* See if there's another address that will work... */			continue;		} 		setsockopt(s, SOL_SOCKET, SO_REUSEADDR,			   (char *)&one, sizeof one);		if (sockopts)			set_socket_options(s, sockopts);		else			set_socket_options(s, lp_socket_options()); #ifdef IPV6_V6ONLY		if (resp->ai_family == AF_INET6) {			if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, (char *)&one, sizeof one) < 0			 && default_af_hint != AF_INET6) {				close(s);				continue;			}		}#endif 		/* Now we've got a socket - we need to bind it. */		if (bind(s, resp->ai_addr, resp->ai_addrlen) < 0) {			/* Nope, try another */			int r = asprintf(&errmsgs[ecnt++],				"bind() failed: %s (address-family %d)\n",				strerror(errno), (int)resp->ai_family);			if (r < 0)				out_of_memory("open_socket_in");			close(s);			continue;		} 		socks[i++] = s;	}	socks[i] = -1; 	if (all_ai)		freeaddrinfo(all_ai); 	/* Only output the socket()/bind() messages if we were totally	 * unsuccessful, or if the daemon is being run with -vv. */	for (s = 0; s < ecnt; s++) {		if (!i || DEBUG_GTE(BIND, 1))			rwrite(FLOG, errmsgs[s], strlen(errmsgs[s]), 0);		free(errmsgs[s]);	}	free(errmsgs); 	if (!i) {		rprintf(FERROR,			"unable to bind any inbound sockets on port %d\n",			port);		free(socks);		return NULL;	}	return socks;}

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