/*      $OpenBSD: server.c,v 1.15 2021/11/03 14:42:12 deraadt Exp $ */
/*
 * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <sys/stat.h>

#include <assert.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <err.h>

#include "extern.h"

static int
fcntl_nonblock(int fd)
{
        int      fl;

        if ((fl = fcntl(fd, F_GETFL, 0)) == -1)
                ERR("fcntl: F_GETFL");
        else if (fcntl(fd, F_SETFL, fl|O_NONBLOCK) == -1)
                ERR("fcntl: F_SETFL");
        else
                return 1;

        return 0;
}

/*
 * The server (remote) side of the system.
 * This parses the arguments given it by the remote shell then moves
 * into receiver or sender mode depending upon those arguments.
 * Returns exit code 0 on success, 1 on failure, 2 on failure with
 * incompatible protocols.
 */
int
rsync_server(const struct opts *opts, size_t argc, char *argv[])
{
        struct sess      sess;
        int              fdin = STDIN_FILENO,
                         fdout = STDOUT_FILENO, rc = 1;

        if (pledge("stdio unix rpath wpath cpath dpath fattr chown getpw unveil",
            NULL) == -1)
                err(ERR_IPC, "pledge");

        memset(&sess, 0, sizeof(struct sess));
        sess.opts = opts;

        /* Begin by making descriptors non-blocking. */

        if (!fcntl_nonblock(fdin) ||
            !fcntl_nonblock(fdout)) {
                ERRX1("fcntl_nonblock");
                goto out;
        }

        /* Standard rsync preamble, server side. */

        sess.lver = RSYNC_PROTOCOL;
        sess.seed = arc4random();

        if (!io_read_int(&sess, fdin, &sess.rver)) {
                ERRX1("io_read_int");
                goto out;
        } else if (!io_write_int(&sess, fdout, sess.lver)) {
                ERRX1("io_write_int");
                goto out;
        } else if (!io_write_int(&sess, fdout, sess.seed)) {
                ERRX1("io_write_int");
                goto out;
        }

        sess.mplex_writes = 1;

        if (sess.rver < sess.lver) {
                ERRX("remote protocol %d is older than our own %d: unsupported",
                    sess.rver, sess.lver);
                rc = 2;
                goto out;
        }

        LOG2("server detected client version %d, server version %d, seed %d",
            sess.rver, sess.lver, sess.seed);

        if (sess.opts->sender) {
                LOG2("server starting sender");

                /*
                 * At this time, I always get a period as the first
                 * argument of the command line.
                 * Let's make it a requirement until I figure out when
                 * that differs.
                 * rsync [flags] "." <source> <...>
                 */

                if (strcmp(argv[0], ".")) {
                        ERRX("first argument must be a standalone period");
                        goto out;
                }
                argv++;
                argc--;
                if (argc == 0) {
                        ERRX("must have arguments");
                        goto out;
                }

                if (!rsync_sender(&sess, fdin, fdout, argc, argv)) {
                        ERRX1("rsync_sender");
                        goto out;
                }
        } else {
                LOG2("server starting receiver");

                /*
                 * I don't understand why this calling convention
                 * exists, but we must adhere to it.
                 * rsync [flags] "." <destination>
                 */

                if (argc != 2) {
                        ERRX("server receiver mode requires two argument");
                        goto out;
                } else if (strcmp(argv[0], ".")) {
                        ERRX("first argument must be a standalone period");
                        goto out;
                }

                if (!rsync_receiver(&sess, fdin, fdout, argv[1])) {
                        ERRX1("rsync_receiver");
                        goto out;
                }
        }

#if 0
        /* Probably the EOF. */
        if (io_read_check(&sess, fdin))
                WARNX("data remains in read pipe");
#endif

        rc = 0;
out:
        return rc;
}