Draft documentation of the client-server protocol.

[rsync/rsync.git] / clientserver.c

/* -*- c-file-style: "linux"; -*-
   
   Copyright (C) 1998-2000 by Andrew Tridgell
   
   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.
*/

/* the socket based protocol for setting up a connection wit rsyncd */

#include "rsync.h"

extern int module_id;
extern int read_only;
extern int verbose;
extern int rsync_port;
char *auth_user;
int sanitize_paths = 0;

int start_socket_client(char *host, char *path, int argc, char *argv[])
{
	int fd, i;
	char *sargs[MAX_ARGS];
	int sargc=0;
	char line[MAXPATHLEN];
	char *p, *user=NULL;
	extern int remote_version;
	extern int am_sender;
	extern struct in_addr socket_address;

	if (argc == 0 && !am_sender) {
		extern int list_only;
		list_only = 1;
	}

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

	p = strchr(host, '@');
	if (p) {
		user = host;
		host = p+1;
		*p = 0;
	}

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

	fd = open_socket_out(host, rsync_port, &socket_address);
	if (fd == -1) {
		exit_cleanup(RERR_SOCKETIO);
	}
	
	server_options(sargs,&sargc);

	sargs[sargc++] = ".";

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

	sargs[sargc] = NULL;

	io_printf(fd,"@RSYNCD: %d\n", PROTOCOL_VERSION);

	if (!read_line(fd, line, sizeof(line)-1)) {
		return -1;
	}

	if (sscanf(line,"@RSYNCD: %d", &remote_version) != 1) {
		return -1;
	}

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

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

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

		if (strcmp(line,"@RSYNCD: OK") == 0) break;
		rprintf(FINFO,"%s\n", line);
	}

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

	if (remote_version < 23) {
		if (remote_version == 22 || (remote_version > 17 && !am_sender))
			io_start_multiplex_in(fd);
	}

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



static int rsync_module(int fd, int i)
{
	int argc=0;
	char *argv[MAX_ARGS];
	char **argp;
	char line[MAXPATHLEN];
	uid_t uid = (uid_t)-2;
	gid_t gid = (gid_t)-2;
	char *p;
	char *addr = client_addr(fd);
	char *host = client_name(fd);
	char *name = lp_name(i);
	int use_chroot = lp_use_chroot(i);
	int start_glob=0;
	int ret;
	char *request=NULL;
	extern int am_sender;
	extern int remote_version;
	extern int am_root;

	if (!allow_access(addr, host, lp_hosts_allow(i), lp_hosts_deny(i))) {
		rprintf(FERROR,"rsync denied on module %s from %s (%s)\n",
			name, client_name(fd), client_addr(fd));
		io_printf(fd,"@ERROR: access denied to %s from %s (%s)\n",
			  name, client_name(fd), client_addr(fd));
		return -1;
	}

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

	
	auth_user = auth_server(fd, i, addr, "@RSYNCD: AUTHREQD ");

	if (!auth_user) {
		rprintf(FERROR,"auth failed on module %s from %s (%s)\n",
			name, client_name(fd), client_addr(fd));
		io_printf(fd,"@ERROR: auth failed on module %s\n",name);
		return -1;		
	}

	module_id = i;

	am_root = (getuid() == 0);

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

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

	p = lp_include_from(i);
	add_exclude_file(p, 1, 1);

	p = lp_include(i);
	add_include_line(p);

	p = lp_exclude_from(i);
	add_exclude_file(p, 1, 0);

	p = lp_exclude(i);
	add_exclude_line(p);

	log_init();

	if (use_chroot) {
		if (chroot(lp_path(i))) {
			rsyserr(FERROR, errno, "chroot %s failed", lp_path(i));
			io_printf(fd,"@ERROR: chroot failed\n");
			return -1;
		}

		if (!push_dir("/", 0)) {
                        rsyserr(FERROR, errno, "chdir %s failed\n", lp_path(i));
			io_printf(fd,"@ERROR: chdir failed\n");
			return -1;
		}

	} else {
		if (!push_dir(lp_path(i), 0)) {
			rsyserr(FERROR, errno, "chdir %s failed\n", lp_path(i));
			io_printf(fd,"@ERROR: chdir failed\n");
			return -1;
		}
		sanitize_paths = 1;
	}

	if (am_root) {
		if (setgid(gid)) {
			rsyserr(FERROR, errno, "setgid %d failed", gid);
			io_printf(fd,"@ERROR: setgid failed\n");
			return -1;
		}

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

		am_root = (getuid() == 0);
	}

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

	argv[argc++] = "rsyncd";

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

		if (!*line) break;

		p = line;

		argv[argc] = strdup(p);
		if (!argv[argc]) {
			return -1;
		}

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

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

		if (argc == MAX_ARGS) {
			return -1;
		}
	}

	if (sanitize_paths) {
		/*
		 * Note that this is applied to all parameters, whether or not
		 *    they are filenames, but no other legal parameters contain
		 *    the forms that need to be sanitized so it doesn't hurt;
		 *    it is not known at this point which parameters are files
		 *    and which aren't.
		 */
		for (i = 1; i < argc; i++) {
			sanitize_path(argv[i], NULL);
		}
	}

	ret = parse_arguments(argc, argv, 0);

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

#if !TRIDGE
	/* don't allow the logs to be flooded too fast */
	if (verbose > 1) verbose = 1;
#endif

	argc -= optind;
	argp = argv + optind;
	optind = 0;

	if (remote_version < 23) {
		if (remote_version == 22 || (remote_version > 17 && am_sender))
			io_start_multiplex_out(fd);
	}

	if (!ret) {
		option_error();
	}

	if (lp_timeout(i)) {
		extern int io_timeout;
		io_timeout = lp_timeout(i);
	}

	start_server(fd, fd, 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));
}

/* this is called when a socket connection is established to a client
   and we want to start talking. The setup of the system is done from
   here */
static int start_daemon(int fd)
{
	char line[200];
	char *motd;
	int i = -1;
	extern char *config_file;
	extern int remote_version;

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

	set_socket_options(fd,"SO_KEEPALIVE");
	set_socket_options(fd,lp_socket_options());
	set_nonblocking(fd);

	io_printf(fd,"@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(fd,"%s", line);
			}
		}
		if (f) fclose(f);
		io_printf(fd,"\n");
	}

	if (!read_line(fd, line, sizeof(line)-1)) {
		return -1;
	}

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

	while (i == -1) {
		line[0] = 0;
		if (!read_line(fd, line, sizeof(line)-1)) {
			return -1;
		}

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

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

		i = lp_number(line);
		if (i == -1) {
			io_printf(fd,"@ERROR: Unknown module '%s'\n", line);
			return -1;
		}
	}

	return rsync_module(fd, i);
}


int daemon_main(void)
{
	extern char *config_file;
	extern int orig_umask;
	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);
	}

	become_daemon();

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

	log_init();

	rprintf(FINFO,"rsyncd version %s starting\n",VERSION);

	if (((pid_file = lp_pid_file()) != NULL) && (*pid_file != '\0')) {
		char pidbuf[16];
		int fd;
		int pid = (int) 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", pid_file);
		    exit_cleanup(RERR_FILEIO);
		}
		slprintf(pidbuf, sizeof(pidbuf), "%d\n", pid);
		write(fd, pidbuf, strlen(pidbuf));
		close(fd);
	}

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