cli-chansession.c - third_party/dropbear - Git at Google

 /*
  * Dropbear SSH
  *
  * Copyright (c) 2002,2003 Matt Johnston
  * Copyright (c) 2004 by Mihnea Stoenescu
  * All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE. */

 #include "includes.h"
 #include "packet.h"
 #include "buffer.h"
 #include "session.h"
 #include "dbutil.h"
 #include "channel.h"
 #include "ssh.h"
 #include "runopts.h"
 #include "termcodes.h"
 #include "chansession.h"
 #include "agentfwd.h"

 static void cli_closechansess(struct Channel *channel);
 static int cli_initchansess(struct Channel *channel);
 static void cli_chansessreq(struct Channel *channel);

 static void send_chansess_pty_req(struct Channel *channel);
 static void send_chansess_shell_req(struct Channel *channel);

 static void cli_tty_setup();

 const struct ChanType clichansess = {
 	0, /* sepfds */
 	"session", /* name */
 	cli_initchansess, /* inithandler */
 	NULL, /* checkclosehandler */
 	cli_chansessreq, /* reqhandler */
 	cli_closechansess, /* closehandler */
 };

 static void cli_chansessreq(struct Channel *channel) {

 	unsigned char* type = NULL;
 	int wantreply;

 	TRACE(("enter cli_chansessreq"))

 	type = buf_getstring(ses.payload, NULL);
 	wantreply = buf_getbool(ses.payload);

 	if (strcmp(type, "exit-status") == 0) {
 		cli_ses.retval = buf_getint(ses.payload);
 		TRACE(("got exit-status of '%d'", cli_ses.retval))
 	} else if (strcmp(type, "exit-signal") == 0) {
 		TRACE(("got exit-signal, ignoring it"))
 	} else {
 		TRACE(("unknown request '%s'", type))
 		send_msg_channel_failure(channel);
 		goto out;
 	}

 out:
 	m_free(type);
 }


 /* If the main session goes, we close it up */
 static void cli_closechansess(struct Channel *UNUSED(channel)) {

 	/* This channel hasn't gone yet, so we have > 1 */
 	if (ses.chancount > 1) {
 		dropbear_log(LOG_INFO, "Waiting for other channels to close...");
 	}

 	cli_tty_cleanup(); /* Restore tty modes etc */

 }

 void cli_start_send_channel_request(struct Channel *channel,
 		unsigned char *type) {

 	CHECKCLEARTOWRITE();
 	buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_REQUEST);
 	buf_putint(ses.writepayload, channel->remotechan);

 	buf_putstring(ses.writepayload, type, strlen(type));

 }

 /* Taken from OpenSSH's sshtty.c:
  * RCSID("OpenBSD: sshtty.c,v 1.5 2003/09/19 17:43:35 markus Exp "); */
 static void cli_tty_setup() {

 	struct termios tio;

 	TRACE(("enter cli_pty_setup"))

 	if (cli_ses.tty_raw_mode == 1) {
 		TRACE(("leave cli_tty_setup: already in raw mode!"))
 		return;
 	}

 	if (tcgetattr(STDIN_FILENO, &tio) == -1) {
 		dropbear_exit("Failed to set raw TTY mode");
 	}

 	/* make a copy */
 	cli_ses.saved_tio = tio;

 	tio.c_iflag |= IGNPAR;
 	tio.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
 #ifdef IUCLC
 	tio.c_iflag &= ~IUCLC;
 #endif
 	tio.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
 #ifdef IEXTEN
 	tio.c_lflag &= ~IEXTEN;
 #endif
 	tio.c_oflag &= ~OPOST;
 	tio.c_cc[VMIN] = 1;
 	tio.c_cc[VTIME] = 0;
 	if (tcsetattr(STDIN_FILENO, TCSADRAIN, &tio) == -1) {
 		dropbear_exit("Failed to set raw TTY mode");
 	}

 	cli_ses.tty_raw_mode = 1;
 	TRACE(("leave cli_tty_setup"))
 }

 void cli_tty_cleanup() {

 	TRACE(("enter cli_tty_cleanup"))

 	if (cli_ses.tty_raw_mode == 0) {
 		TRACE(("leave cli_tty_cleanup: not in raw mode"))
 		return;
 	}

 	if (tcsetattr(STDIN_FILENO, TCSADRAIN, &cli_ses.saved_tio) == -1) {
 		dropbear_log(LOG_WARNING, "Failed restoring TTY");
 	} else {
 		cli_ses.tty_raw_mode = 0;
 	}

 	TRACE(("leave cli_tty_cleanup"))
 }

 static void put_termcodes() {

 	struct termios tio;
 	unsigned int sshcode;
 	const struct TermCode *termcode;
 	unsigned int value;
 	unsigned int mapcode;

 	unsigned int bufpos1, bufpos2;

 	TRACE(("enter put_termcodes"))

 	if (tcgetattr(STDIN_FILENO, &tio) == -1) {
 		dropbear_log(LOG_WARNING, "Failed reading termmodes");
 		buf_putint(ses.writepayload, 1); /* Just the terminator */
 		buf_putbyte(ses.writepayload, 0); /* TTY_OP_END */
 		return;
 	}

 	bufpos1 = ses.writepayload->pos;
 	buf_putint(ses.writepayload, 0); /* A placeholder for the final length */

 	/* As with Dropbear server, we ignore baud rates for now */
 	for (sshcode = 1; sshcode < MAX_TERMCODE; sshcode++) {

 		termcode = &termcodes[sshcode];
 		mapcode = termcode->mapcode;

 		switch (termcode->type) {

 			case TERMCODE_NONE:
 				continue;

 			case TERMCODE_CONTROLCHAR:
 				value = tio.c_cc[mapcode];
 				break;

 			case TERMCODE_INPUT:
 				value = tio.c_iflag & mapcode;
 				break;

 			case TERMCODE_OUTPUT:
 				value = tio.c_oflag & mapcode;
 				break;

 			case TERMCODE_LOCAL:
 				value = tio.c_lflag & mapcode;
 				break;

 			case TERMCODE_CONTROL:
 				value = tio.c_cflag & mapcode;
 				break;

 			default:
 				continue;

 		}

 		/* If we reach here, we have something to say */
 		buf_putbyte(ses.writepayload, sshcode);
 		buf_putint(ses.writepayload, value);
 	}

 	buf_putbyte(ses.writepayload, 0); /* THE END, aka TTY_OP_END */

 	/* Put the string length at the start of the buffer */
 	bufpos2 = ses.writepayload->pos;

 	buf_setpos(ses.writepayload, bufpos1); /* Jump back */
 	buf_putint(ses.writepayload, bufpos2 - bufpos1 - 4); /* len(termcodes) */
 	buf_setpos(ses.writepayload, bufpos2); /* Back where we were */

 	TRACE(("leave put_termcodes"))
 }

 static void put_winsize() {

 	struct winsize ws;

 	if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0) {
 		/* Some sane defaults */
 		ws.ws_row = 25;
 		ws.ws_col = 80;
 		ws.ws_xpixel = 0;
 		ws.ws_ypixel = 0;
 	}

 	buf_putint(ses.writepayload, ws.ws_col); /* Cols */
 	buf_putint(ses.writepayload, ws.ws_row); /* Rows */
 	buf_putint(ses.writepayload, ws.ws_xpixel); /* Width */
 	buf_putint(ses.writepayload, ws.ws_ypixel); /* Height */

 }

 static void sigwinch_handler(int UNUSED(unused)) {

 	cli_ses.winchange = 1;

 }

 void cli_chansess_winchange() {

 	unsigned int i;
 	struct Channel *channel = NULL;

 	for (i = 0; i < ses.chansize; i++) {
 		channel = ses.channels[i];
 		if (channel != NULL && channel->type == &clichansess) {
 			CHECKCLEARTOWRITE();
 			buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_REQUEST);
 			buf_putint(ses.writepayload, channel->remotechan);
 			buf_putstring(ses.writepayload, "window-change", 13);
 			buf_putbyte(ses.writepayload, 0); /* FALSE says the spec */
 			put_winsize();
 			encrypt_packet();
 		}
 	}
 	cli_ses.winchange = 0;
 }

 static void send_chansess_pty_req(struct Channel *channel) {

 	unsigned char* term = NULL;

 	TRACE(("enter send_chansess_pty_req"))

 	cli_start_send_channel_request(channel, "pty-req");

 	/* Don't want replies */
 	buf_putbyte(ses.writepayload, 0);

 	/* Get the terminal */
 	term = getenv("TERM");
 	if (term == NULL) {
 		term = "vt100"; /* Seems a safe default */
 	}
 	buf_putstring(ses.writepayload, term, strlen(term));

 	/* Window size */
 	put_winsize();

 	/* Terminal mode encoding */
 	put_termcodes();

 	encrypt_packet();

 	/* Set up a window-change handler */
 	if (signal(SIGWINCH, sigwinch_handler) == SIG_ERR) {
 		dropbear_exit("Signal error");
 	}
 	TRACE(("leave send_chansess_pty_req"))
 }

 static void send_chansess_shell_req(struct Channel *channel) {

 	unsigned char* reqtype = NULL;

 	TRACE(("enter send_chansess_shell_req"))

 	if (cli_opts.cmd) {
 		if (cli_opts.is_subsystem) {
 			reqtype = "subsystem";
 		} else {
 			reqtype = "exec";
 		}
 	} else {
 		reqtype = "shell";
 	}

 	cli_start_send_channel_request(channel, reqtype);

 	/* XXX TODO */
 	buf_putbyte(ses.writepayload, 0); /* Don't want replies */
 	if (cli_opts.cmd) {
 		buf_putstring(ses.writepayload, cli_opts.cmd, strlen(cli_opts.cmd));
 	}

 	encrypt_packet();
 	TRACE(("leave send_chansess_shell_req"))
 }

 /* Shared for normal client channel and netcat-alike */
 static int cli_init_stdpipe_sess(struct Channel *channel) {
 	channel->writefd = STDOUT_FILENO;
 	setnonblocking(STDOUT_FILENO);

 	channel->readfd = STDIN_FILENO;
 	setnonblocking(STDIN_FILENO);

 	channel->errfd = STDERR_FILENO;
 	setnonblocking(STDERR_FILENO);

 	channel->extrabuf = cbuf_new(opts.recv_window);
 	return 0;
 }

 static int cli_initchansess(struct Channel *channel) {

 	cli_init_stdpipe_sess(channel);

 #ifdef ENABLE_CLI_AGENTFWD
 	if (cli_opts.agent_fwd) {
 		cli_setup_agent(channel);
 	}
 #endif

 	if (cli_opts.wantpty) {
 		send_chansess_pty_req(channel);
 	}

 	send_chansess_shell_req(channel);

 	if (cli_opts.wantpty) {
 		cli_tty_setup();
 	}

 	return 0; /* Success */
 }

 #ifdef ENABLE_CLI_NETCAT

 static const struct ChanType cli_chan_netcat = {
 	0, /* sepfds */
 	"direct-tcpip",
 	cli_init_stdpipe_sess, /* inithandler */
 	NULL,
 	NULL,
 	cli_closechansess
 };

 void cli_send_netcat_request() {

 	const unsigned char* source_host = "127.0.0.1";
 	const int source_port = 22;

 	cli_opts.wantpty = 0;

 	if (send_msg_channel_open_init(STDIN_FILENO, &cli_chan_netcat)
 			== DROPBEAR_FAILURE) {
 		dropbear_exit("Couldn't open initial channel");
 	}

 	buf_putstring(ses.writepayload, cli_opts.netcat_host,
 			strlen(cli_opts.netcat_host));
 	buf_putint(ses.writepayload, cli_opts.netcat_port);

 	/* originator ip - localhost is accurate enough */
 	buf_putstring(ses.writepayload, source_host, strlen(source_host));
 	buf_putint(ses.writepayload, source_port);

 	encrypt_packet();
 	TRACE(("leave cli_send_chansess_request"))
 }
 #endif

 void cli_send_chansess_request() {

 	TRACE(("enter cli_send_chansess_request"))

 	if (send_msg_channel_open_init(STDIN_FILENO, &clichansess)
 			== DROPBEAR_FAILURE) {
 		dropbear_exit("Couldn't open initial channel");
 	}

 	/* No special channel request data */
 	encrypt_packet();
 	TRACE(("leave cli_send_chansess_request"))

 }
	/*
	* Dropbear SSH
	*
	* Copyright (c) 2002,2003 Matt Johnston
	* Copyright (c) 2004 by Mihnea Stoenescu
	* All rights reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	* SOFTWARE. */

	#include "includes.h"
	#include "packet.h"
	#include "buffer.h"
	#include "session.h"
	#include "dbutil.h"
	#include "channel.h"
	#include "ssh.h"
	#include "runopts.h"
	#include "termcodes.h"
	#include "chansession.h"
	#include "agentfwd.h"

	static void cli_closechansess(struct Channel *channel);
	static int cli_initchansess(struct Channel *channel);
	static void cli_chansessreq(struct Channel *channel);

	static void send_chansess_pty_req(struct Channel *channel);
	static void send_chansess_shell_req(struct Channel *channel);

	static void cli_tty_setup();

	const struct ChanType clichansess = {
	0, /* sepfds */
	"session", /* name */
	cli_initchansess, /* inithandler */
	NULL, /* checkclosehandler */
	cli_chansessreq, /* reqhandler */
	cli_closechansess, /* closehandler */
	};

	static void cli_chansessreq(struct Channel *channel) {

	unsigned char* type = NULL;
	int wantreply;

	TRACE(("enter cli_chansessreq"))

	type = buf_getstring(ses.payload, NULL);
	wantreply = buf_getbool(ses.payload);

	if (strcmp(type, "exit-status") == 0) {
	cli_ses.retval = buf_getint(ses.payload);
	TRACE(("got exit-status of '%d'", cli_ses.retval))
	} else if (strcmp(type, "exit-signal") == 0) {
	TRACE(("got exit-signal, ignoring it"))
	} else {
	TRACE(("unknown request '%s'", type))
	send_msg_channel_failure(channel);
	goto out;
	}

	out:
	m_free(type);
	}


	/* If the main session goes, we close it up */
	static void cli_closechansess(struct Channel *UNUSED(channel)) {

	/* This channel hasn't gone yet, so we have > 1 */
	if (ses.chancount > 1) {
	dropbear_log(LOG_INFO, "Waiting for other channels to close...");
	}

	cli_tty_cleanup(); /* Restore tty modes etc */

	}

	void cli_start_send_channel_request(struct Channel *channel,
	unsigned char *type) {

	CHECKCLEARTOWRITE();
	buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_REQUEST);
	buf_putint(ses.writepayload, channel->remotechan);

	buf_putstring(ses.writepayload, type, strlen(type));

	}

	/* Taken from OpenSSH's sshtty.c:
	* RCSID("OpenBSD: sshtty.c,v 1.5 2003/09/19 17:43:35 markus Exp "); */
	static void cli_tty_setup() {

	struct termios tio;

	TRACE(("enter cli_pty_setup"))

	if (cli_ses.tty_raw_mode == 1) {
	TRACE(("leave cli_tty_setup: already in raw mode!"))
	return;
	}

	if (tcgetattr(STDIN_FILENO, &tio) == -1) {
	dropbear_exit("Failed to set raw TTY mode");
	}

	/* make a copy */
	cli_ses.saved_tio = tio;

	tio.c_iflag \|= IGNPAR;
	tio.c_iflag &= ~(ISTRIP \| INLCR \| IGNCR \| ICRNL \| IXON \| IXANY \| IXOFF);
	#ifdef IUCLC
	tio.c_iflag &= ~IUCLC;
	#endif
	tio.c_lflag &= ~(ISIG \| ICANON \| ECHO \| ECHOE \| ECHOK \| ECHONL);
	#ifdef IEXTEN
	tio.c_lflag &= ~IEXTEN;
	#endif
	tio.c_oflag &= ~OPOST;
	tio.c_cc[VMIN] = 1;
	tio.c_cc[VTIME] = 0;
	if (tcsetattr(STDIN_FILENO, TCSADRAIN, &tio) == -1) {
	dropbear_exit("Failed to set raw TTY mode");
	}

	cli_ses.tty_raw_mode = 1;
	TRACE(("leave cli_tty_setup"))
	}

	void cli_tty_cleanup() {

	TRACE(("enter cli_tty_cleanup"))

	if (cli_ses.tty_raw_mode == 0) {
	TRACE(("leave cli_tty_cleanup: not in raw mode"))
	return;
	}

	if (tcsetattr(STDIN_FILENO, TCSADRAIN, &cli_ses.saved_tio) == -1) {
	dropbear_log(LOG_WARNING, "Failed restoring TTY");
	} else {
	cli_ses.tty_raw_mode = 0;
	}

	TRACE(("leave cli_tty_cleanup"))
	}

	static void put_termcodes() {

	struct termios tio;
	unsigned int sshcode;
	const struct TermCode *termcode;
	unsigned int value;
	unsigned int mapcode;

	unsigned int bufpos1, bufpos2;

	TRACE(("enter put_termcodes"))

	if (tcgetattr(STDIN_FILENO, &tio) == -1) {
	dropbear_log(LOG_WARNING, "Failed reading termmodes");
	buf_putint(ses.writepayload, 1); /* Just the terminator */
	buf_putbyte(ses.writepayload, 0); /* TTY_OP_END */
	return;
	}

	bufpos1 = ses.writepayload->pos;
	buf_putint(ses.writepayload, 0); /* A placeholder for the final length */

	/* As with Dropbear server, we ignore baud rates for now */
	for (sshcode = 1; sshcode < MAX_TERMCODE; sshcode++) {

	termcode = &termcodes[sshcode];
	mapcode = termcode->mapcode;

	switch (termcode->type) {

	case TERMCODE_NONE:
	continue;

	case TERMCODE_CONTROLCHAR:
	value = tio.c_cc[mapcode];
	break;

	case TERMCODE_INPUT:
	value = tio.c_iflag & mapcode;
	break;

	case TERMCODE_OUTPUT:
	value = tio.c_oflag & mapcode;
	break;

	case TERMCODE_LOCAL:
	value = tio.c_lflag & mapcode;
	break;

	case TERMCODE_CONTROL:
	value = tio.c_cflag & mapcode;
	break;

	default:
	continue;

	}

	/* If we reach here, we have something to say */
	buf_putbyte(ses.writepayload, sshcode);
	buf_putint(ses.writepayload, value);
	}

	buf_putbyte(ses.writepayload, 0); /* THE END, aka TTY_OP_END */

	/* Put the string length at the start of the buffer */
	bufpos2 = ses.writepayload->pos;

	buf_setpos(ses.writepayload, bufpos1); /* Jump back */
	buf_putint(ses.writepayload, bufpos2 - bufpos1 - 4); /* len(termcodes) */
	buf_setpos(ses.writepayload, bufpos2); /* Back where we were */

	TRACE(("leave put_termcodes"))
	}

	static void put_winsize() {

	struct winsize ws;

	if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0) {
	/* Some sane defaults */
	ws.ws_row = 25;
	ws.ws_col = 80;
	ws.ws_xpixel = 0;
	ws.ws_ypixel = 0;
	}

	buf_putint(ses.writepayload, ws.ws_col); /* Cols */
	buf_putint(ses.writepayload, ws.ws_row); /* Rows */
	buf_putint(ses.writepayload, ws.ws_xpixel); /* Width */
	buf_putint(ses.writepayload, ws.ws_ypixel); /* Height */

	}

	static void sigwinch_handler(int UNUSED(unused)) {

	cli_ses.winchange = 1;

	}

	void cli_chansess_winchange() {

	unsigned int i;
	struct Channel *channel = NULL;

	for (i = 0; i < ses.chansize; i++) {
	channel = ses.channels[i];
	if (channel != NULL && channel->type == &clichansess) {
	CHECKCLEARTOWRITE();
	buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_REQUEST);
	buf_putint(ses.writepayload, channel->remotechan);
	buf_putstring(ses.writepayload, "window-change", 13);
	buf_putbyte(ses.writepayload, 0); /* FALSE says the spec */
	put_winsize();
	encrypt_packet();
	}
	}
	cli_ses.winchange = 0;
	}

	static void send_chansess_pty_req(struct Channel *channel) {

	unsigned char* term = NULL;

	TRACE(("enter send_chansess_pty_req"))

	cli_start_send_channel_request(channel, "pty-req");

	/* Don't want replies */
	buf_putbyte(ses.writepayload, 0);

	/* Get the terminal */
	term = getenv("TERM");
	if (term == NULL) {
	term = "vt100"; /* Seems a safe default */
	}
	buf_putstring(ses.writepayload, term, strlen(term));

	/* Window size */
	put_winsize();

	/* Terminal mode encoding */
	put_termcodes();

	encrypt_packet();

	/* Set up a window-change handler */
	if (signal(SIGWINCH, sigwinch_handler) == SIG_ERR) {
	dropbear_exit("Signal error");
	}
	TRACE(("leave send_chansess_pty_req"))
	}

	static void send_chansess_shell_req(struct Channel *channel) {

	unsigned char* reqtype = NULL;

	TRACE(("enter send_chansess_shell_req"))

	if (cli_opts.cmd) {
	if (cli_opts.is_subsystem) {
	reqtype = "subsystem";
	} else {
	reqtype = "exec";
	}
	} else {
	reqtype = "shell";
	}

	cli_start_send_channel_request(channel, reqtype);

	/* XXX TODO */
	buf_putbyte(ses.writepayload, 0); /* Don't want replies */
	if (cli_opts.cmd) {
	buf_putstring(ses.writepayload, cli_opts.cmd, strlen(cli_opts.cmd));
	}

	encrypt_packet();
	TRACE(("leave send_chansess_shell_req"))
	}

	/* Shared for normal client channel and netcat-alike */
	static int cli_init_stdpipe_sess(struct Channel *channel) {
	channel->writefd = STDOUT_FILENO;
	setnonblocking(STDOUT_FILENO);

	channel->readfd = STDIN_FILENO;
	setnonblocking(STDIN_FILENO);

	channel->errfd = STDERR_FILENO;
	setnonblocking(STDERR_FILENO);

	channel->extrabuf = cbuf_new(opts.recv_window);
	return 0;
	}

	static int cli_initchansess(struct Channel *channel) {

	cli_init_stdpipe_sess(channel);

	#ifdef ENABLE_CLI_AGENTFWD
	if (cli_opts.agent_fwd) {
	cli_setup_agent(channel);
	}
	#endif

	if (cli_opts.wantpty) {
	send_chansess_pty_req(channel);
	}

	send_chansess_shell_req(channel);

	if (cli_opts.wantpty) {
	cli_tty_setup();
	}

	return 0; /* Success */
	}

	#ifdef ENABLE_CLI_NETCAT

	static const struct ChanType cli_chan_netcat = {
	0, /* sepfds */
	"direct-tcpip",
	cli_init_stdpipe_sess, /* inithandler */
	NULL,
	NULL,
	cli_closechansess
	};

	void cli_send_netcat_request() {

	const unsigned char* source_host = "127.0.0.1";
	const int source_port = 22;

	cli_opts.wantpty = 0;

	if (send_msg_channel_open_init(STDIN_FILENO, &cli_chan_netcat)
	== DROPBEAR_FAILURE) {
	dropbear_exit("Couldn't open initial channel");
	}

	buf_putstring(ses.writepayload, cli_opts.netcat_host,
	strlen(cli_opts.netcat_host));
	buf_putint(ses.writepayload, cli_opts.netcat_port);

	/* originator ip - localhost is accurate enough */
	buf_putstring(ses.writepayload, source_host, strlen(source_host));
	buf_putint(ses.writepayload, source_port);

	encrypt_packet();
	TRACE(("leave cli_send_chansess_request"))
	}
	#endif

	void cli_send_chansess_request() {

	TRACE(("enter cli_send_chansess_request"))

	if (send_msg_channel_open_init(STDIN_FILENO, &clichansess)
	== DROPBEAR_FAILURE) {
	dropbear_exit("Couldn't open initial channel");
	}

	/* No special channel request data */
	encrypt_packet();
	TRACE(("leave cli_send_chansess_request"))

	}