clientserver.c - android_external_rsync - Gitiles

 /* -*- c-file-style: "linux"; -*-
  *
  * Copyright (C) 1998-2001 by Andrew Tridgell <tridge@samba.org>
  * Copyright (C) 2001-2002 by Martin Pool <mbp@samba.org>
  *
  * 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
  *
  * The socket based protocol for setting up a connection with
  * rsyncd.
  **/

 #include "rsync.h"

 extern int verbose;
 extern int list_only;
 extern int am_sender;
 extern int am_server;
 extern int am_daemon;
 extern int am_root;
 extern int rsync_port;
 extern int kluge_around_eof;
 extern int daemon_over_rsh;
 extern int sanitize_paths;
 extern int filesfrom_fd;
 extern int remote_protocol;
 extern int protocol_version;
 extern int io_timeout;
 extern int orig_umask;
 extern int no_detach;
 extern int default_af_hint;
 extern char *bind_address;
 extern struct filter_list_struct server_filter_list;
 extern char *config_file;
 extern char *files_from;

 char *auth_user;
 int read_only = 0;
 int daemon_log_format_has_i = 0;
 int daemon_log_format_has_o_or_i = 0;
 int module_id = -1;

 /* Length of lp_path() string when in daemon mode & not chrooted, else 0. */
 unsigned int module_dirlen = 0;

 /**
  * Run a client connected to an rsyncd.  The alternative to this
  * function for remote-shell connections is do_cmd().
  *
  * After negotiating which module to use and reading the server's
  * motd, this hands over to client_run().  Telling the server the
  * module will cause it to chroot/setuid/etc.
  *
  * Instead of doing a transfer, the client may at this stage instead
  * get a listing of remote modules and exit.
  *
  * @return -1 for error in startup, or the result of client_run().
  * Either way, it eventually gets passed to exit_cleanup().
  **/
 int start_socket_client(char *host, char *path, int argc, char *argv[])
 {
 	int fd, ret;
 	char *p, *user = NULL;

 	/* This is redundant with code in start_inband_exchange(), but this
 	 * short-circuits a problem in the client before we open a socket,
 	 * and the extra check won't hurt. */
 	if (*path == '/') {
 		rprintf(FERROR,
 			"ERROR: The remote path must start with a module name not a /\n");
 		return -1;
 	}

 	if ((p = strrchr(host, '@')) != NULL) {
 		user = host;
 		host = p+1;
 		*p = '\0';
 	}

 	fd = open_socket_out_wrapped(host, rsync_port, bind_address,
 				     default_af_hint);
 	if (fd == -1)
 		exit_cleanup(RERR_SOCKETIO);

 	ret = start_inband_exchange(user, path, fd, fd, argc);

 	return ret ? ret : client_run(fd, fd, -1, argc, argv);
 }

 int start_inband_exchange(char *user, char *path, int f_in, int f_out,
 			  int argc)
 {
 	int i;
 	char *sargs[MAX_ARGS];
 	int sargc = 0;
 	char line[MAXPATHLEN];
 	char *p;

 	if (argc == 0 && !am_sender)
 		list_only |= 1;

 	if (*path == '/') {
 		rprintf(FERROR,
 			"ERROR: The remote path must start with a module name\n");
 		return -1;
 	}

 	if (!user)
 		user = getenv("USER");
 	if (!user)
 		user = getenv("LOGNAME");

 	io_printf(f_out, "@RSYNCD: %d\n", protocol_version);

 	if (!read_line(f_in, line, sizeof line - 1)) {
 		rprintf(FERROR, "rsync: did not see server greeting\n");
 		return -1;
 	}

 	if (sscanf(line,"@RSYNCD: %d", &remote_protocol) != 1) {
 		/* note that read_line strips of \n or \r */
 		rprintf(FERROR, "rsync: server sent \"%s\" rather than greeting\n",
 			line);
 		return -1;
 	}
 	if (protocol_version > remote_protocol)
 		protocol_version = remote_protocol;

 	if (list_only && protocol_version >= 29)
 		list_only |= 2;

 	/* set daemon_over_rsh to false since we need to build the
 	 * true set of args passed through the rsh/ssh connection;
 	 * this is a no-op for direct-socket-connection mode */
 	daemon_over_rsh = 0;
 	server_options(sargs, &sargc);

 	sargs[sargc++] = ".";

 	if (path && *path)
 		sargs[sargc++] = path;

 	sargs[sargc] = NULL;

 	if (verbose > 1)
 		print_child_argv(sargs);

 	p = strchr(path,'/');
 	if (p) *p = 0;
 	io_printf(f_out, "%s\n", path);
 	if (p) *p = '/';

 	/* Old servers may just drop the connection here,
 	 rather than sending a proper EXIT command.  Yuck. */
 	kluge_around_eof = list_only && protocol_version < 25 ? 1 : 0;

 	while (1) {
 		if (!read_line(f_in, line, sizeof line - 1)) {
 			rprintf(FERROR, "rsync: didn't get server startup line\n");
 			return -1;
 		}

 		if (strncmp(line,"@RSYNCD: AUTHREQD ",18) == 0) {
 			auth_client(f_out, user, line+18);
 			continue;
 		}

 		if (strcmp(line,"@RSYNCD: OK") == 0)
 			break;

 		if (strcmp(line,"@RSYNCD: EXIT") == 0) {
 			/* This is sent by recent versions of the
 			 * server to terminate the listing of modules.
 			 * We don't want to go on and transfer
 			 * anything; just exit. */
 			exit(0);
 		}

 		if (strncmp(line, "@ERROR", 6) == 0) {
 			rprintf(FERROR, "%s\n", line);
 			/* This is always fatal; the server will now
 			 * close the socket. */
 			return -1;
 		}

 		rprintf(FINFO, "%s\n", line);
 	}
 	kluge_around_eof = 0;

 	for (i = 0; i < sargc; i++) {
 		io_printf(f_out, "%s\n", sargs[i]);
 	}
 	io_printf(f_out, "\n");

 	if (protocol_version < 23) {
 		if (protocol_version == 22 || !am_sender)
 			io_start_multiplex_in();
 	}

 	return 0;
 }


 static int rsync_module(int f_in, int f_out, int i)
 {
 	int argc = 0;
 	int maxargs;
 	char **argv;
 	char **argp;
 	char line[MAXPATHLEN];
 	uid_t uid = (uid_t)-2;  /* canonically "nobody" */
 	gid_t gid = (gid_t)-2;
 	char *p;
 	char *addr = client_addr(f_in);
 	char *host = client_name(f_in);
 	char *name = lp_name(i);
 	int use_chroot = lp_use_chroot(i);
 	int start_glob = 0;
 	int ret;
 	char *request = NULL;

 	if (!allow_access(addr, host, lp_hosts_allow(i), lp_hosts_deny(i))) {
 		rprintf(FLOG, "rsync denied on module %s from %s (%s)\n",
 			name, host, addr);
 		if (!lp_list(i))
 			io_printf(f_out, "@ERROR: Unknown module '%s'\n", name);
 		else {
 			io_printf(f_out,
 				  "@ERROR: access denied to %s from %s (%s)\n",
 				  name, host, addr);
 		}
 		return -1;
 	}

 	if (am_daemon && am_server) {
 		rprintf(FLOG, "rsync allowed access on module %s from %s (%s)\n",
 			name, host, addr);
 	}

 	if (!claim_connection(lp_lock_file(i), lp_max_connections(i))) {
 		if (errno) {
 			rsyserr(FLOG, errno, "failed to open lock file %s",
 				safe_fname(lp_lock_file(i)));
 			io_printf(f_out, "@ERROR: failed to open lock file\n");
 		} else {
 			rprintf(FLOG, "max connections (%d) reached\n",
 				lp_max_connections(i));
 			io_printf(f_out, "@ERROR: max connections (%d) reached -- try again later\n",
 				lp_max_connections(i));
 		}
 		return -1;
 	}

 	auth_user = auth_server(f_in, f_out, i, host, addr, "@RSYNCD: AUTHREQD ");

 	if (!auth_user) {
 		io_printf(f_out, "@ERROR: auth failed on module %s\n", name);
 		return -1;
 	}

 	module_id = i;

 	if (lp_read_only(i))
 		read_only = 1;

 	if (lp_transfer_logging(i)) {
 		if (log_format_has(lp_log_format(i), 'i'))
 			daemon_log_format_has_i = 1;
 		if (daemon_log_format_has_i
 		    || log_format_has(lp_log_format(i), 'o'))
 			daemon_log_format_has_o_or_i = 1;
 	}

 	am_root = (MY_UID() == 0);

 	if (am_root) {
 		p = lp_uid(i);
 		if (!name_to_uid(p, &uid)) {
 			if (!isdigit(*(unsigned char *)p)) {
 				rprintf(FLOG, "Invalid uid %s\n", p);
 				io_printf(f_out, "@ERROR: invalid uid %s\n", p);
 				return -1;
 			}
 			uid = atoi(p);
 		}

 		p = lp_gid(i);
 		if (!name_to_gid(p, &gid)) {
 			if (!isdigit(*(unsigned char *)p)) {
 				rprintf(FLOG, "Invalid gid %s\n", p);
 				io_printf(f_out, "@ERROR: invalid gid %s\n", p);
 				return -1;
 			}
 			gid = atoi(p);
 		}
 	}

 	/* TODO: If we're not root, but the configuration requests
 	 * that we change to some uid other than the current one, then
 	 * log a warning. */

 	/* TODO: Perhaps take a list of gids, and make them into the
 	 * supplementary groups. */

 	if (use_chroot || (module_dirlen = strlen(lp_path(i))) == 1) {
 		module_dirlen = 0;
 		set_filter_dir("/", 1);
 	} else
 		set_filter_dir(lp_path(i), module_dirlen);

 	p = lp_filter(i);
 	parse_rule(&server_filter_list, p, MATCHFLG_WORD_SPLIT,
 		   XFLG_ANCHORED2ABS);

 	p = lp_include_from(i);
 	parse_filter_file(&server_filter_list, p, MATCHFLG_INCLUDE,
 	    XFLG_ANCHORED2ABS | XFLG_OLD_PREFIXES | XFLG_FATAL_ERRORS);

 	p = lp_include(i);
 	parse_rule(&server_filter_list, p,
 		   MATCHFLG_INCLUDE | MATCHFLG_WORD_SPLIT,
 		   XFLG_ANCHORED2ABS | XFLG_OLD_PREFIXES);

 	p = lp_exclude_from(i);
 	parse_filter_file(&server_filter_list, p, 0,
 	    XFLG_ANCHORED2ABS | XFLG_OLD_PREFIXES | XFLG_FATAL_ERRORS);

 	p = lp_exclude(i);
 	parse_rule(&server_filter_list, p, MATCHFLG_WORD_SPLIT,
 		   XFLG_ANCHORED2ABS | XFLG_OLD_PREFIXES);

 	log_init();

 	if (use_chroot) {
 		/*
 		 * XXX: The 'use chroot' flag is a fairly reliable
 		 * source of confusion, because it fails under two
 		 * important circumstances: running as non-root,
 		 * running on Win32 (or possibly others).  On the
 		 * other hand, if you are running as root, then it
 		 * might be better to always use chroot.
 		 *
 		 * So, perhaps if we can't chroot we should just issue
 		 * a warning, unless a "require chroot" flag is set,
 		 * in which case we fail.
 		 */
 		if (chroot(lp_path(i))) {
 			rsyserr(FLOG, errno, "chroot %s failed",
 				safe_fname(lp_path(i)));
 			io_printf(f_out, "@ERROR: chroot failed\n");
 			return -1;
 		}

 		if (!push_dir("/")) {
 			rsyserr(FLOG, errno, "chdir %s failed\n",
 				safe_fname(lp_path(i)));
 			io_printf(f_out, "@ERROR: chdir failed\n");
 			return -1;
 		}

 	} else {
 		if (!push_dir(lp_path(i))) {
 			rsyserr(FLOG, errno, "chdir %s failed\n",
 				safe_fname(lp_path(i)));
 			io_printf(f_out, "@ERROR: chdir failed\n");
 			return -1;
 		}
 		sanitize_paths = 1;
 	}

 	if (am_root) {
 		/* XXXX: You could argue that if the daemon is started
 		 * by a non-root user and they explicitly specify a
 		 * gid, then we should try to change to that gid --
 		 * this could be possible if it's already in their
 		 * supplementary groups. */

 		/* TODO: Perhaps we need to document that if rsyncd is
 		 * started by somebody other than root it will inherit
 		 * all their supplementary groups. */

 		if (setgid(gid)) {
 			rsyserr(FLOG, errno, "setgid %d failed", (int)gid);
 			io_printf(f_out, "@ERROR: setgid failed\n");
 			return -1;
 		}
 #ifdef HAVE_SETGROUPS
 		/* Get rid of any supplementary groups this process
 		 * might have inheristed. */
 		if (setgroups(1, &gid)) {
 			rsyserr(FLOG, errno, "setgroups failed");
 			io_printf(f_out, "@ERROR: setgroups failed\n");
 			return -1;
 		}
 #endif

 		if (setuid(uid)) {
 			rsyserr(FLOG, errno, "setuid %d failed", (int)uid);
 			io_printf(f_out, "@ERROR: setuid failed\n");
 			return -1;
 		}

 		am_root = (MY_UID() == 0);
 	}

 	io_printf(f_out, "@RSYNCD: OK\n");

 	maxargs = MAX_ARGS;
 	if (!(argv = new_array(char *, maxargs)))
 		out_of_memory("rsync_module");
 	argv[argc++] = "rsyncd";

 	while (1) {
 		if (!read_line(f_in, line, sizeof line - 1))
 			return -1;

 		if (!*line)
 			break;

 		p = line;

 		if (argc == maxargs) {
 			maxargs += MAX_ARGS;
 			if (!(argv = realloc_array(argv, char *, maxargs)))
 				out_of_memory("rsync_module");
 		}
 		if (!(argv[argc] = strdup(p)))
 			out_of_memory("rsync_module");

 		if (start_glob) {
 			if (start_glob == 1) {
 				request = strdup(p);
 				start_glob++;
 			}
 			glob_expand(name, &argv, &argc, &maxargs);
 		} else
 			argc++;

 		if (strcmp(line, ".") == 0)
 			start_glob = 1;
 	}

 	verbose = 0; /* future verbosity is controlled by client options */
 	argp = argv;
 	ret = parse_arguments(&argc, (const char ***) &argp, 0);

 	if (filesfrom_fd == 0)
 		filesfrom_fd = f_in;

 	if (request) {
 		if (*auth_user) {
 			rprintf(FLOG, "rsync %s %s from %s@%s (%s)\n",
 				am_sender ? "on" : "to",
 				request, auth_user, host, addr);
 		} else {
 			rprintf(FLOG, "rsync %s %s from %s (%s)\n",
 				am_sender ? "on" : "to",
 				request, host, addr);
 		}
 		free(request);
 	}

 #ifndef DEBUG
 	/* don't allow the logs to be flooded too fast */
 	if (verbose > lp_max_verbosity())
 		verbose = lp_max_verbosity();
 #endif

 	if (protocol_version < 23
 	    && (protocol_version == 22 || am_sender))
 		io_start_multiplex_out();
 	else if (!ret) {
 		/* We have to get I/O multiplexing started so that we can
 		 * get the error back to the client.  This means getting
 		 * the protocol setup finished first in later versions. */
 		setup_protocol(f_out, f_in);
 		if (!am_sender) {
 			/* Since we failed in our option parsing, we may not
 			 * have finished parsing that the client sent us a
 			 * --files-from option, so look for it manually.
 			 * Without this, the socket would be in the wrong
 			 * state for the upcoming error message. */
 			if (!files_from) {
 				int i;
 				for (i = 0; i < argc; i++) {
 					if (strncmp(argv[i], "--files-from", 12) == 0) {
 						files_from = "";
 						break;
 					}
 				}
 			}
 			if (files_from)
 				write_byte(f_out, 0);
 		}
 		io_start_multiplex_out();
 	}

 	if (!ret) {
 		option_error();
 		msleep(400);
 		exit_cleanup(RERR_UNSUPPORTED);
 	}

 	if (lp_timeout(i) && lp_timeout(i) > io_timeout)
 		set_io_timeout(lp_timeout(i));

 	start_server(f_in, f_out, argc, argp);

 	return 0;
 }

 /* send a list of available modules to the client. Don't list those
    with "list = False". */
 static void send_listing(int fd)
 {
 	int n = lp_numservices();
 	int i;

 	for (i = 0; i < n; i++) {
 		if (lp_list(i))
 			io_printf(fd, "%-15s\t%s\n", lp_name(i), lp_comment(i));
 	}

 	if (protocol_version >= 25)
 		io_printf(fd,"@RSYNCD: EXIT\n");
 }

 /* this is called when a connection is established to a client
    and we want to start talking. The setup of the system is done from
    here */
 int start_daemon(int f_in, int f_out)
 {
 	char line[200];
 	char *motd;
 	int i;

 	io_set_sock_fds(f_in, f_out);

 	if (!lp_load(config_file, 0))
 		exit_cleanup(RERR_SYNTAX);

 	log_init();

 	if (!am_server) {
 		set_socket_options(f_in, "SO_KEEPALIVE");
 		set_socket_options(f_in, lp_socket_options());
 		set_nonblocking(f_in);
 	}

 	io_printf(f_out, "@RSYNCD: %d\n", protocol_version);

 	motd = lp_motd_file();
 	if (motd && *motd) {
 		FILE *f = fopen(motd,"r");
 		while (f && !feof(f)) {
 			int len = fread(line, 1, sizeof line - 1, f);
 			if (len > 0) {
 				line[len] = 0;
 				io_printf(f_out, "%s", line);
 			}
 		}
 		if (f)
 			fclose(f);
 		io_printf(f_out, "\n");
 	}

 	if (!read_line(f_in, line, sizeof line - 1))
 		return -1;

 	if (sscanf(line,"@RSYNCD: %d", &remote_protocol) != 1) {
 		io_printf(f_out, "@ERROR: protocol startup error\n");
 		return -1;
 	}
 	if (protocol_version > remote_protocol)
 		protocol_version = remote_protocol;

 	line[0] = 0;
 	if (!read_line(f_in, line, sizeof line - 1))
 		return -1;

 	if (!*line || strcmp(line, "#list") == 0) {
 		send_listing(f_out);
 		return -1;
 	}

 	if (*line == '#') {
 		/* it's some sort of command that I don't understand */
 		io_printf(f_out, "@ERROR: Unknown command '%s'\n", line);
 		return -1;
 	}

 	if ((i = lp_number(line)) < 0) {
 		char *addr = client_addr(f_in);
 		char *host = client_name(f_in);
 		rprintf(FLOG, "unknown module '%s' tried from %s (%s)\n",
 			line, host, addr);
 		io_printf(f_out, "@ERROR: Unknown module '%s'\n", line);
 		return -1;
 	}

 	return rsync_module(f_in, f_out, i);
 }


 int daemon_main(void)
 {
 	char *pid_file;

 	if (is_a_socket(STDIN_FILENO)) {
 		int i;

 		/* we are running via inetd - close off stdout and
 		 * stderr so that library functions (and getopt) don't
 		 * try to use them. Redirect them to /dev/null */
 		for (i = 1; i < 3; i++) {
 			close(i);
 			open("/dev/null", O_RDWR);
 		}

 		return start_daemon(STDIN_FILENO, STDIN_FILENO);
 	}

 	if (!no_detach)
 		become_daemon();

 	if (!lp_load(config_file, 1))
 		exit_cleanup(RERR_SYNTAX);

 	if (rsync_port == 0 && (rsync_port = lp_rsync_port()) == 0)
 		rsync_port = RSYNC_PORT;
 	if (bind_address == NULL && *lp_bind_address())
 		bind_address = lp_bind_address();

 	log_init();

 	rprintf(FLOG, "rsyncd version %s starting, listening on port %d\n",
 		RSYNC_VERSION, rsync_port);
 	/* TODO: If listening on a particular address, then show that
 	 * address too.  In fact, why not just do inet_ntop on the
 	 * local address??? */

 	if (((pid_file = lp_pid_file()) != NULL) && (*pid_file != '\0')) {
 		char pidbuf[16];
 		int fd;
 		pid_t pid = getpid();
 		cleanup_set_pid(pid);
 		if ((fd = do_open(lp_pid_file(), O_WRONLY|O_CREAT|O_TRUNC,
 					0666 & ~orig_umask)) == -1) {
 			cleanup_set_pid(0);
 			rsyserr(FLOG, errno, "failed to create pid file %s",
 				safe_fname(pid_file));
 			exit_cleanup(RERR_FILEIO);
 		}
 		snprintf(pidbuf, sizeof pidbuf, "%ld\n", (long)pid);
 		write(fd, pidbuf, strlen(pidbuf));
 		close(fd);
 	}

 	start_accept_loop(rsync_port, start_daemon);
 	return -1;
 }
	/* -- c-file-style: "linux"; --
	*
	* Copyright (C) 1998-2001 by Andrew Tridgell <tridge@samba.org>
	* Copyright (C) 2001-2002 by Martin Pool <mbp@samba.org>
	*
	* 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
	*
	* The socket based protocol for setting up a connection with
	* rsyncd.
	**/

	#include "rsync.h"

	extern int verbose;
	extern int list_only;
	extern int am_sender;
	extern int am_server;
	extern int am_daemon;
	extern int am_root;
	extern int rsync_port;
	extern int kluge_around_eof;
	extern int daemon_over_rsh;
	extern int sanitize_paths;
	extern int filesfrom_fd;
	extern int remote_protocol;
	extern int protocol_version;
	extern int io_timeout;
	extern int orig_umask;
	extern int no_detach;
	extern int default_af_hint;
	extern char *bind_address;
	extern struct filter_list_struct server_filter_list;
	extern char *config_file;
	extern char *files_from;

	char *auth_user;
	int read_only = 0;
	int daemon_log_format_has_i = 0;
	int daemon_log_format_has_o_or_i = 0;
	int module_id = -1;

	/* Length of lp_path() string when in daemon mode & not chrooted, else 0. */
	unsigned int module_dirlen = 0;

	/**
	* Run a client connected to an rsyncd. The alternative to this
	* function for remote-shell connections is do_cmd().
	*
	* After negotiating which module to use and reading the server's
	* motd, this hands over to client_run(). Telling the server the
	* module will cause it to chroot/setuid/etc.
	*
	* Instead of doing a transfer, the client may at this stage instead
	* get a listing of remote modules and exit.
	*
	* @return -1 for error in startup, or the result of client_run().
	* Either way, it eventually gets passed to exit_cleanup().
	**/
	int start_socket_client(char host, char path, int argc, char *argv[])
	{
	int fd, ret;
	char p, user = NULL;

	/* This is redundant with code in start_inband_exchange(), but this
	* short-circuits a problem in the client before we open a socket,
	* and the extra check won't hurt. */
	if (*path == '/') {
	rprintf(FERROR,
	"ERROR: The remote path must start with a module name not a /\n");
	return -1;
	}

	if ((p = strrchr(host, '@')) != NULL) {
	user = host;
	host = p+1;
	*p = '\0';
	}

	fd = open_socket_out_wrapped(host, rsync_port, bind_address,
	default_af_hint);
	if (fd == -1)
	exit_cleanup(RERR_SOCKETIO);

	ret = start_inband_exchange(user, path, fd, fd, argc);

	return ret ? ret : client_run(fd, fd, -1, argc, argv);
	}

	int start_inband_exchange(char user, char path, int f_in, int f_out,
	int argc)
	{
	int i;
	char *sargs[MAX_ARGS];
	int sargc = 0;
	char line[MAXPATHLEN];
	char *p;

	if (argc == 0 && !am_sender)
	list_only \|= 1;

	if (*path == '/') {
	rprintf(FERROR,
	"ERROR: The remote path must start with a module name\n");
	return -1;
	}

	if (!user)
	user = getenv("USER");
	if (!user)
	user = getenv("LOGNAME");

	io_printf(f_out, "@RSYNCD: %d\n", protocol_version);

	if (!read_line(f_in, line, sizeof line - 1)) {
	rprintf(FERROR, "rsync: did not see server greeting\n");
	return -1;
	}

	if (sscanf(line,"@RSYNCD: %d", &remote_protocol) != 1) {
	/* note that read_line strips of \n or \r */
	rprintf(FERROR, "rsync: server sent \"%s\" rather than greeting\n",
	line);
	return -1;
	}
	if (protocol_version > remote_protocol)
	protocol_version = remote_protocol;

	if (list_only && protocol_version >= 29)
	list_only \|= 2;

	/* set daemon_over_rsh to false since we need to build the
	* true set of args passed through the rsh/ssh connection;
	* this is a no-op for direct-socket-connection mode */
	daemon_over_rsh = 0;
	server_options(sargs, &sargc);

	sargs[sargc++] = ".";

	if (path && *path)
	sargs[sargc++] = path;

	sargs[sargc] = NULL;

	if (verbose > 1)
	print_child_argv(sargs);

	p = strchr(path,'/');
	if (p) *p = 0;
	io_printf(f_out, "%s\n", path);
	if (p) *p = '/';

	/* Old servers may just drop the connection here,
	rather than sending a proper EXIT command. Yuck. */
	kluge_around_eof = list_only && protocol_version < 25 ? 1 : 0;

	while (1) {
	if (!read_line(f_in, line, sizeof line - 1)) {
	rprintf(FERROR, "rsync: didn't get server startup line\n");
	return -1;
	}

	if (strncmp(line,"@RSYNCD: AUTHREQD ",18) == 0) {
	auth_client(f_out, user, line+18);
	continue;
	}

	if (strcmp(line,"@RSYNCD: OK") == 0)
	break;

	if (strcmp(line,"@RSYNCD: EXIT") == 0) {
	/* This is sent by recent versions of the
	* server to terminate the listing of modules.
	* We don't want to go on and transfer
	* anything; just exit. */
	exit(0);
	}

	if (strncmp(line, "@ERROR", 6) == 0) {
	rprintf(FERROR, "%s\n", line);
	/* This is always fatal; the server will now
	* close the socket. */
	return -1;
	}

	rprintf(FINFO, "%s\n", line);
	}
	kluge_around_eof = 0;

	for (i = 0; i < sargc; i++) {
	io_printf(f_out, "%s\n", sargs[i]);
	}
	io_printf(f_out, "\n");

	if (protocol_version < 23) {
	if (protocol_version == 22 \|\| !am_sender)
	io_start_multiplex_in();
	}

	return 0;
	}



	static int rsync_module(int f_in, int f_out, int i)
	{
	int argc = 0;
	int maxargs;
	char **argv;
	char **argp;
	char line[MAXPATHLEN];
	uid_t uid = (uid_t)-2; /* canonically "nobody" */
	gid_t gid = (gid_t)-2;
	char *p;
	char *addr = client_addr(f_in);
	char *host = client_name(f_in);
	char *name = lp_name(i);
	int use_chroot = lp_use_chroot(i);
	int start_glob = 0;
	int ret;
	char *request = NULL;

	if (!allow_access(addr, host, lp_hosts_allow(i), lp_hosts_deny(i))) {
	rprintf(FLOG, "rsync denied on module %s from %s (%s)\n",
	name, host, addr);
	if (!lp_list(i))
	io_printf(f_out, "@ERROR: Unknown module '%s'\n", name);
	else {
	io_printf(f_out,
	"@ERROR: access denied to %s from %s (%s)\n",
	name, host, addr);
	}
	return -1;
	}

	if (am_daemon && am_server) {
	rprintf(FLOG, "rsync allowed access on module %s from %s (%s)\n",
	name, host, addr);
	}

	if (!claim_connection(lp_lock_file(i), lp_max_connections(i))) {
	if (errno) {
	rsyserr(FLOG, errno, "failed to open lock file %s",
	safe_fname(lp_lock_file(i)));
	io_printf(f_out, "@ERROR: failed to open lock file\n");
	} else {
	rprintf(FLOG, "max connections (%d) reached\n",
	lp_max_connections(i));
	io_printf(f_out, "@ERROR: max connections (%d) reached -- try again later\n",
	lp_max_connections(i));
	}
	return -1;
	}

	auth_user = auth_server(f_in, f_out, i, host, addr, "@RSYNCD: AUTHREQD ");

	if (!auth_user) {
	io_printf(f_out, "@ERROR: auth failed on module %s\n", name);
	return -1;
	}

	module_id = i;

	if (lp_read_only(i))
	read_only = 1;

	if (lp_transfer_logging(i)) {
	if (log_format_has(lp_log_format(i), 'i'))
	daemon_log_format_has_i = 1;
	if (daemon_log_format_has_i
	\|\| log_format_has(lp_log_format(i), 'o'))
	daemon_log_format_has_o_or_i = 1;
	}

	am_root = (MY_UID() == 0);

	if (am_root) {
	p = lp_uid(i);
	if (!name_to_uid(p, &uid)) {
	if (!isdigit((unsigned char )p)) {
	rprintf(FLOG, "Invalid uid %s\n", p);
	io_printf(f_out, "@ERROR: invalid uid %s\n", p);
	return -1;
	}
	uid = atoi(p);
	}

	p = lp_gid(i);
	if (!name_to_gid(p, &gid)) {
	if (!isdigit((unsigned char )p)) {
	rprintf(FLOG, "Invalid gid %s\n", p);
	io_printf(f_out, "@ERROR: invalid gid %s\n", p);
	return -1;
	}
	gid = atoi(p);
	}
	}

	/* TODO: If we're not root, but the configuration requests
	* that we change to some uid other than the current one, then
	* log a warning. */

	/* TODO: Perhaps take a list of gids, and make them into the
	* supplementary groups. */

	if (use_chroot \|\| (module_dirlen = strlen(lp_path(i))) == 1) {
	module_dirlen = 0;
	set_filter_dir("/", 1);
	} else
	set_filter_dir(lp_path(i), module_dirlen);

	p = lp_filter(i);
	parse_rule(&server_filter_list, p, MATCHFLG_WORD_SPLIT,
	XFLG_ANCHORED2ABS);

	p = lp_include_from(i);
	parse_filter_file(&server_filter_list, p, MATCHFLG_INCLUDE,
	XFLG_ANCHORED2ABS \| XFLG_OLD_PREFIXES \| XFLG_FATAL_ERRORS);

	p = lp_include(i);
	parse_rule(&server_filter_list, p,
	MATCHFLG_INCLUDE \| MATCHFLG_WORD_SPLIT,
	XFLG_ANCHORED2ABS \| XFLG_OLD_PREFIXES);

	p = lp_exclude_from(i);
	parse_filter_file(&server_filter_list, p, 0,
	XFLG_ANCHORED2ABS \| XFLG_OLD_PREFIXES \| XFLG_FATAL_ERRORS);

	p = lp_exclude(i);
	parse_rule(&server_filter_list, p, MATCHFLG_WORD_SPLIT,
	XFLG_ANCHORED2ABS \| XFLG_OLD_PREFIXES);

	log_init();

	if (use_chroot) {
	/*
	* XXX: The 'use chroot' flag is a fairly reliable
	* source of confusion, because it fails under two
	* important circumstances: running as non-root,
	* running on Win32 (or possibly others). On the
	* other hand, if you are running as root, then it
	* might be better to always use chroot.
	*
	* So, perhaps if we can't chroot we should just issue
	* a warning, unless a "require chroot" flag is set,
	* in which case we fail.
	*/
	if (chroot(lp_path(i))) {
	rsyserr(FLOG, errno, "chroot %s failed",
	safe_fname(lp_path(i)));
	io_printf(f_out, "@ERROR: chroot failed\n");
	return -1;
	}

	if (!push_dir("/")) {
	rsyserr(FLOG, errno, "chdir %s failed\n",
	safe_fname(lp_path(i)));
	io_printf(f_out, "@ERROR: chdir failed\n");
	return -1;
	}

	} else {
	if (!push_dir(lp_path(i))) {
	rsyserr(FLOG, errno, "chdir %s failed\n",
	safe_fname(lp_path(i)));
	io_printf(f_out, "@ERROR: chdir failed\n");
	return -1;
	}
	sanitize_paths = 1;
	}

	if (am_root) {
	/* XXXX: You could argue that if the daemon is started
	* by a non-root user and they explicitly specify a
	* gid, then we should try to change to that gid --
	* this could be possible if it's already in their
	* supplementary groups. */

	/* TODO: Perhaps we need to document that if rsyncd is
	* started by somebody other than root it will inherit
	* all their supplementary groups. */

	if (setgid(gid)) {
	rsyserr(FLOG, errno, "setgid %d failed", (int)gid);
	io_printf(f_out, "@ERROR: setgid failed\n");
	return -1;
	}
	#ifdef HAVE_SETGROUPS
	/* Get rid of any supplementary groups this process
	* might have inheristed. */
	if (setgroups(1, &gid)) {
	rsyserr(FLOG, errno, "setgroups failed");
	io_printf(f_out, "@ERROR: setgroups failed\n");
	return -1;
	}
	#endif

	if (setuid(uid)) {
	rsyserr(FLOG, errno, "setuid %d failed", (int)uid);
	io_printf(f_out, "@ERROR: setuid failed\n");
	return -1;
	}

	am_root = (MY_UID() == 0);
	}

	io_printf(f_out, "@RSYNCD: OK\n");

	maxargs = MAX_ARGS;
	if (!(argv = new_array(char *, maxargs)))
	out_of_memory("rsync_module");
	argv[argc++] = "rsyncd";

	while (1) {
	if (!read_line(f_in, line, sizeof line - 1))
	return -1;

	if (!*line)
	break;

	p = line;

	if (argc == maxargs) {
	maxargs += MAX_ARGS;
	if (!(argv = realloc_array(argv, char *, maxargs)))
	out_of_memory("rsync_module");
	}
	if (!(argv[argc] = strdup(p)))
	out_of_memory("rsync_module");

	if (start_glob) {
	if (start_glob == 1) {
	request = strdup(p);
	start_glob++;
	}
	glob_expand(name, &argv, &argc, &maxargs);
	} else
	argc++;

	if (strcmp(line, ".") == 0)
	start_glob = 1;
	}

	verbose = 0; /* future verbosity is controlled by client options */
	argp = argv;
	ret = parse_arguments(&argc, (const char ***) &argp, 0);

	if (filesfrom_fd == 0)
	filesfrom_fd = f_in;

	if (request) {
	if (*auth_user) {
	rprintf(FLOG, "rsync %s %s from %s@%s (%s)\n",
	am_sender ? "on" : "to",
	request, auth_user, host, addr);
	} else {
	rprintf(FLOG, "rsync %s %s from %s (%s)\n",
	am_sender ? "on" : "to",
	request, host, addr);
	}
	free(request);
	}

	#ifndef DEBUG
	/* don't allow the logs to be flooded too fast */
	if (verbose > lp_max_verbosity())
	verbose = lp_max_verbosity();
	#endif

	if (protocol_version < 23
	&& (protocol_version == 22 \|\| am_sender))
	io_start_multiplex_out();
	else if (!ret) {
	/* We have to get I/O multiplexing started so that we can
	* get the error back to the client. This means getting
	* the protocol setup finished first in later versions. */
	setup_protocol(f_out, f_in);
	if (!am_sender) {
	/* Since we failed in our option parsing, we may not
	* have finished parsing that the client sent us a
	* --files-from option, so look for it manually.
	* Without this, the socket would be in the wrong
	* state for the upcoming error message. */
	if (!files_from) {
	int i;
	for (i = 0; i < argc; i++) {
	if (strncmp(argv[i], "--files-from", 12) == 0) {
	files_from = "";
	break;
	}
	}
	}
	if (files_from)
	write_byte(f_out, 0);
	}
	io_start_multiplex_out();
	}

	if (!ret) {
	option_error();
	msleep(400);
	exit_cleanup(RERR_UNSUPPORTED);
	}

	if (lp_timeout(i) && lp_timeout(i) > io_timeout)
	set_io_timeout(lp_timeout(i));

	start_server(f_in, f_out, argc, argp);

	return 0;
	}

	/* send a list of available modules to the client. Don't list those
	with "list = False". */
	static void send_listing(int fd)
	{
	int n = lp_numservices();
	int i;

	for (i = 0; i < n; i++) {
	if (lp_list(i))
	io_printf(fd, "%-15s\t%s\n", lp_name(i), lp_comment(i));
	}

	if (protocol_version >= 25)
	io_printf(fd,"@RSYNCD: EXIT\n");
	}

	/* this is called when a connection is established to a client
	and we want to start talking. The setup of the system is done from
	here */
	int start_daemon(int f_in, int f_out)
	{
	char line[200];
	char *motd;
	int i;

	io_set_sock_fds(f_in, f_out);

	if (!lp_load(config_file, 0))
	exit_cleanup(RERR_SYNTAX);

	log_init();

	if (!am_server) {
	set_socket_options(f_in, "SO_KEEPALIVE");
	set_socket_options(f_in, lp_socket_options());
	set_nonblocking(f_in);
	}

	io_printf(f_out, "@RSYNCD: %d\n", protocol_version);

	motd = lp_motd_file();
	if (motd && *motd) {
	FILE *f = fopen(motd,"r");
	while (f && !feof(f)) {
	int len = fread(line, 1, sizeof line - 1, f);
	if (len > 0) {
	line[len] = 0;
	io_printf(f_out, "%s", line);
	}
	}
	if (f)
	fclose(f);
	io_printf(f_out, "\n");
	}

	if (!read_line(f_in, line, sizeof line - 1))
	return -1;

	if (sscanf(line,"@RSYNCD: %d", &remote_protocol) != 1) {
	io_printf(f_out, "@ERROR: protocol startup error\n");
	return -1;
	}
	if (protocol_version > remote_protocol)
	protocol_version = remote_protocol;

	line[0] = 0;
	if (!read_line(f_in, line, sizeof line - 1))
	return -1;

	if (!*line \|\| strcmp(line, "#list") == 0) {
	send_listing(f_out);
	return -1;
	}

	if (*line == '#') {
	/* it's some sort of command that I don't understand */
	io_printf(f_out, "@ERROR: Unknown command '%s'\n", line);
	return -1;
	}

	if ((i = lp_number(line)) < 0) {
	char *addr = client_addr(f_in);
	char *host = client_name(f_in);
	rprintf(FLOG, "unknown module '%s' tried from %s (%s)\n",
	line, host, addr);
	io_printf(f_out, "@ERROR: Unknown module '%s'\n", line);
	return -1;
	}

	return rsync_module(f_in, f_out, i);
	}


	int daemon_main(void)
	{
	char *pid_file;

	if (is_a_socket(STDIN_FILENO)) {
	int i;

	/* we are running via inetd - close off stdout and
	* stderr so that library functions (and getopt) don't
	* try to use them. Redirect them to /dev/null */
	for (i = 1; i < 3; i++) {
	close(i);
	open("/dev/null", O_RDWR);
	}

	return start_daemon(STDIN_FILENO, STDIN_FILENO);
	}

	if (!no_detach)
	become_daemon();

	if (!lp_load(config_file, 1))
	exit_cleanup(RERR_SYNTAX);

	if (rsync_port == 0 && (rsync_port = lp_rsync_port()) == 0)
	rsync_port = RSYNC_PORT;
	if (bind_address == NULL && *lp_bind_address())
	bind_address = lp_bind_address();

	log_init();

	rprintf(FLOG, "rsyncd version %s starting, listening on port %d\n",
	RSYNC_VERSION, rsync_port);
	/* TODO: If listening on a particular address, then show that
	* address too. In fact, why not just do inet_ntop on the
	* local address??? */

	if (((pid_file = lp_pid_file()) != NULL) && (*pid_file != '\0')) {
	char pidbuf[16];
	int fd;
	pid_t pid = getpid();
	cleanup_set_pid(pid);
	if ((fd = do_open(lp_pid_file(), O_WRONLY\|O_CREAT\|O_TRUNC,
	0666 & ~orig_umask)) == -1) {
	cleanup_set_pid(0);
	rsyserr(FLOG, errno, "failed to create pid file %s",
	safe_fname(pid_file));
	exit_cleanup(RERR_FILEIO);
	}
	snprintf(pidbuf, sizeof pidbuf, "%ld\n", (long)pid);
	write(fd, pidbuf, strlen(pidbuf));
	close(fd);
	}

	start_accept_loop(rsync_port, start_daemon);
	return -1;
	}