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Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

/* $OpenBSD: client.c,v 1.7 2009/07/26 12:58:44 nicm Exp $ */

/*
 * Copyright (c) 2007 Nicholas Marriott <nicm@users.sourceforge.net>
 *
 * 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 MIND, 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/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/wait.h>

#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "tmux.h"

void	client_handle_winch(struct client_ctx *);

int
client_init(char *path, struct client_ctx *cctx, int cmdflags, int flags)
{
	struct sockaddr_un		sa;
	struct stat			sb;
	struct msg_identify_data	data;
	struct winsize			ws;
	size_t				size;
	int				mode;
	char			       *name, *term;
	char		 		rpathbuf[MAXPATHLEN];

	if (realpath(path, rpathbuf) == NULL)
		strlcpy(rpathbuf, path, sizeof rpathbuf);
	setproctitle("client (%s)", rpathbuf);

	if (lstat(path, &sb) != 0) {
		if (cmdflags & CMD_STARTSERVER && errno == ENOENT) {
			if ((cctx->srv_fd = server_start(path)) == -1)
				goto start_failed;
			goto server_started;
		}
		goto not_found;
	}
	if (!S_ISSOCK(sb.st_mode)) {
		errno = ENOTSOCK;
		goto not_found;
	}

	memset(&sa, 0, sizeof sa);
	sa.sun_family = AF_UNIX;
	size = strlcpy(sa.sun_path, path, sizeof sa.sun_path);
	if (size >= sizeof sa.sun_path) {
		errno = ENAMETOOLONG;
		goto not_found;
	}

	if ((cctx->srv_fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
		fatal("socket");

	if (connect(
	    cctx->srv_fd, (struct sockaddr *) &sa, SUN_LEN(&sa)) == -1) {
		if (errno == ECONNREFUSED) {
			if (unlink(path) != 0 || !(cmdflags & CMD_STARTSERVER))
				goto not_found;
			if ((cctx->srv_fd = server_start(path)) == -1)
				goto start_failed;
			goto server_started;
		}
		goto not_found;
	}

server_started:
	if ((mode = fcntl(cctx->srv_fd, F_GETFL)) == -1)
		fatal("fcntl failed");
	if (fcntl(cctx->srv_fd, F_SETFL, mode|O_NONBLOCK) == -1)
		fatal("fcntl failed");
	cctx->srv_in = buffer_create(BUFSIZ);
	cctx->srv_out = buffer_create(BUFSIZ);

	if (isatty(STDIN_FILENO)) {
		if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) == -1)
			fatal("ioctl(TIOCGWINSZ)");
		data.version = PROTOCOL_VERSION;
		data.flags = flags;
		data.sx = ws.ws_col;
		data.sy = ws.ws_row;

		if (getcwd(data.cwd, sizeof data.cwd) == NULL)
			*data.cwd = '\0';

		*data.term = '\0';
		if ((term = getenv("TERM")) != NULL) {
			if (strlcpy(data.term,
			    term, sizeof data.term) >= sizeof data.term)
				*data.term = '\0';
		}

		*data.tty = '\0';
		if ((name = ttyname(STDIN_FILENO)) == NULL)
			fatal("ttyname failed");
		if (strlcpy(data.tty, name, sizeof data.tty) >= sizeof data.tty)
			fatalx("ttyname failed");

		client_write_server(cctx, MSG_IDENTIFY, &data, sizeof data);
	}

	return (0);

start_failed:
	log_warnx("server failed to start");
	return (1);

not_found:
	log_warn("server not found");
	return (1);
}

int
client_main(struct client_ctx *cctx)
{
	struct pollfd	 pfd;
	int		 xtimeout; /* Yay for ncurses namespace! */

	siginit();

	logfile("client");

	while (!sigterm) {
		if (sigchld) {
			waitpid(WAIT_ANY, NULL, WNOHANG);
			sigchld = 0;
		}
		if (sigwinch)
			client_handle_winch(cctx);
		if (sigcont) {
			siginit();
			client_write_server(cctx, MSG_WAKEUP, NULL, 0);
			sigcont = 0;
		}

		switch (client_msg_dispatch(cctx)) {
		case -1:
			goto out;
		case 0:
			/* May be more in buffer, don't let poll block. */
			xtimeout = 0;
			break;
		default:
			/* Out of data, poll may block. */
			xtimeout = INFTIM;
			break;
		}

		pfd.fd = cctx->srv_fd;
		pfd.events = POLLIN;
		if (BUFFER_USED(cctx->srv_out) > 0)
			pfd.events |= POLLOUT;

		if (poll(&pfd, 1, xtimeout) == -1) {
			if (errno == EAGAIN || errno == EINTR)
				continue;
			fatal("poll failed");
		}

		if (buffer_poll(&pfd, cctx->srv_in, cctx->srv_out) != 0) {
			cctx->exittype = CCTX_DIED;
			break;
		}
	}

out:
 	if (sigterm) {
 		printf("[terminated]\n");
 		return (1);
 	}
	switch (cctx->exittype) {
	case CCTX_DIED:
		printf("[lost server]\n");
		return (0);
	case CCTX_SHUTDOWN:
		printf("[server exited]\n");
		return (0);
	case CCTX_EXIT:
		printf("[exited]\n");
		return (0);
	case CCTX_DETACH:
		printf("[detached]\n");
		return (0);
	default:
		printf("[error: %s]\n", cctx->errstr);
		return (1);
	}
}

void
client_handle_winch(struct client_ctx *cctx)
{
	struct msg_resize_data	data;
	struct winsize		ws;

	if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) == -1)
		fatal("ioctl failed");

	data.sx = ws.ws_col;
	data.sy = ws.ws_row;
	client_write_server(cctx, MSG_RESIZE, &data, sizeof data);

	sigwinch = 0;
}