Added the new --protocol option.

[rsync.git] / clientserver.c

/* -*- 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 module_id;
extern int read_only;
extern int verbose;
extern int rsync_port;
char *auth_user;
extern int sanitize_paths;
extern int filesfrom_fd;
extern int remote_protocol;
extern int protocol_version;
extern struct exclude_struct **server_exclude_list;
extern char *exclude_path_prefix;

/**
 * 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;
        extern char *bind_address;
        extern int default_af_hint;

        /* this is redundant with code in start_inband_exchange(), but
         * this short-circuits a problem 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;
        }

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

        if (verbose >= 2) {
                /* FIXME: If we're going to use a socket program for
                 * testing, then this message is wrong.  We need to
                 * say something like "(except really using %s)" */
                rprintf(FINFO, "opening tcp connection to %s port %d\n",
                        host, rsync_port);
        }
        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 < 0? 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;
        extern int kludge_around_eof;
        extern int am_sender;
        extern int daemon_over_rsh;
        extern int list_only;

        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");

        /* 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;

        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;

        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. */
        kludge_around_eof = list_only && (protocol_version < 25);

        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 RERR_STARTCLIENT;
                } else {
                        rprintf(FINFO,"%s\n", line);
                }
        }
        kludge_around_eof = False;

        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 || (protocol_version > 17 && !am_sender))
                        io_start_multiplex_in(f_in);
        }

        return 0;
}



static int rsync_module(int f_in, int f_out, int i)
{
        int argc=0;
        char *argv[MAX_ARGS];
        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;
        extern int am_sender;
        extern int am_server;
        extern int am_daemon;
        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, host, addr);
                io_printf(f_out, "@ERROR: access denied to %s from %s (%s)\n",
                          name, host, addr);
                return -1;
        }

        if (am_daemon && am_server) {
                rprintf(FINFO, "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) {
                        rprintf(FERROR,"failed to open lock file %s : %s\n",
                                lp_lock_file(i), strerror(errno));
                        io_printf(f_out, "@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(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, addr, "@RSYNCD: AUTHREQD ");

        if (!auth_user) {
                rprintf(FERROR,"auth failed on module %s from %s (%s)\n",
                        name, host, addr);
                io_printf(f_out, "@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(* (unsigned char *) p)) {
                                rprintf(FERROR,"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(FERROR,"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. */

        exclude_path_prefix = use_chroot? "" : lp_path(i);

        p = lp_include_from(i);
        add_exclude_file(&server_exclude_list, p, MISSING_FATAL, ADD_INCLUDE);

        p = lp_include(i);
        add_exclude_line(&server_exclude_list, p, ADD_INCLUDE);

        p = lp_exclude_from(i);
        add_exclude_file(&server_exclude_list, p, MISSING_FATAL, ADD_EXCLUDE);

        p = lp_exclude(i);
        add_exclude_line(&server_exclude_list, p, ADD_EXCLUDE);

        exclude_path_prefix = NULL;

        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(FERROR, errno, "chroot %s failed", lp_path(i));
                        io_printf(f_out, "@ERROR: chroot failed\n");
                        return -1;
                }

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

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

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

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

        argv[argc++] = "rsyncd";

        while (1) {
                if (!read_line(f_in, 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);
                }
        }

        argp = argv;
        ret = parse_arguments(&argc, (const char ***) &argp, 0);

        if (filesfrom_fd == 0)
                filesfrom_fd = f_in;

        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);
        }

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

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

        /* For later protocol versions, we don't start multiplexing
         * until we've configured nonblocking in start_server.  That
         * means we're in a sticky situation now: there's no way to
         * convey errors to the client. */

        /* FIXME: Hold off on reporting option processing errors until
         * we've set up nonblocking and multiplexed IO and can get the
         * message back to them. */
        if (!ret) {
                option_error();
                exit_cleanup(RERR_UNSUPPORTED);
        }

        if (lp_timeout(i)) {
                extern int io_timeout;
                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 = -1;
        extern char *config_file;
        extern int am_server;

        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;

        while (i == -1) {
                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;
                }

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

        return rsync_module(f_in, f_out, i);
}


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

        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);
        }

        log_init();

        rprintf(FINFO, "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;
                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);
                }
                snprintf(pidbuf, sizeof(pidbuf), "%d\n", pid);
                write(fd, pidbuf, strlen(pidbuf));
                close(fd);
        }

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