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Add options ClientAliveInterval and ClientAliveCountMax to sshd.
This gives the ability to do a "keepalive" via the encrypted channel
which can't be spoofed (unlike TCP keepalives). Useful for when you want
to use ssh connections to authenticate people for something, and know
relatively quickly when they are no longer authenticated. Disabled
by default (of course). ok markus@

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Server main loop for handling the interactive session.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 *
 * SSH2 support by Markus Friedl.
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"
RCSID("$OpenBSD: serverloop.c,v 1.61 2001/04/13 22:46:54 beck Exp $");

#include "xmalloc.h"
#include "packet.h"
#include "buffer.h"
#include "log.h"
#include "servconf.h"
#include "sshpty.h"
#include "channels.h"
#include "compat.h"
#include "ssh1.h"
#include "ssh2.h"
#include "auth.h"
#include "session.h"
#include "dispatch.h"
#include "auth-options.h"
#include "serverloop.h"
#include "misc.h"
#include "kex.h"

extern ServerOptions options;

/* XXX */
extern Kex *xxx_kex;

static Buffer stdin_buffer;	/* Buffer for stdin data. */
static Buffer stdout_buffer;	/* Buffer for stdout data. */
static Buffer stderr_buffer;	/* Buffer for stderr data. */
static int fdin;		/* Descriptor for stdin (for writing) */
static int fdout;		/* Descriptor for stdout (for reading);
				   May be same number as fdin. */
static int fderr;		/* Descriptor for stderr.  May be -1. */
static long stdin_bytes = 0;	/* Number of bytes written to stdin. */
static long stdout_bytes = 0;	/* Number of stdout bytes sent to client. */
static long stderr_bytes = 0;	/* Number of stderr bytes sent to client. */
static long fdout_bytes = 0;	/* Number of stdout bytes read from program. */
static int stdin_eof = 0;	/* EOF message received from client. */
static int fdout_eof = 0;	/* EOF encountered reading from fdout. */
static int fderr_eof = 0;	/* EOF encountered readung from fderr. */
static int fdin_is_tty = 0;	/* fdin points to a tty. */
static int connection_in;	/* Connection to client (input). */
static int connection_out;	/* Connection to client (output). */
static int connection_closed = 0;	/* Connection to client closed. */
static u_int buffer_high;	/* "Soft" max buffer size. */

/*
 * This SIGCHLD kludge is used to detect when the child exits.  The server
 * will exit after that, as soon as forwarded connections have terminated.
 */

static pid_t child_pid;			/* Pid of the child. */
static volatile int child_terminated;	/* The child has terminated. */
static volatile int child_wait_status;	/* Status from wait(). */

void	server_init_dispatch(void);

int client_alive_timeouts = 0;

void
sigchld_handler(int sig)
{
	int save_errno = errno;
	pid_t wait_pid;

	debug("Received SIGCHLD.");
	wait_pid = wait((int *) &child_wait_status);
	if (wait_pid != -1) {
		if (wait_pid != child_pid)
			error("Strange, got SIGCHLD and wait returned pid %d but child is %d",
			      wait_pid, child_pid);
		if (WIFEXITED(child_wait_status) ||
		    WIFSIGNALED(child_wait_status))
			child_terminated = 1;
	}
	signal(SIGCHLD, sigchld_handler);
	errno = save_errno;
}
void
sigchld_handler2(int sig)
{
	int save_errno = errno;
	debug("Received SIGCHLD.");
	child_terminated = 1;
	signal(SIGCHLD, sigchld_handler2);
	errno = save_errno;
}

/*
 * Make packets from buffered stderr data, and buffer it for sending
 * to the client.
 */
void
make_packets_from_stderr_data(void)
{
	int len;

	/* Send buffered stderr data to the client. */
	while (buffer_len(&stderr_buffer) > 0 &&
	    packet_not_very_much_data_to_write()) {
		len = buffer_len(&stderr_buffer);
		if (packet_is_interactive()) {
			if (len > 512)
				len = 512;
		} else {
			/* Keep the packets at reasonable size. */
			if (len > packet_get_maxsize())
				len = packet_get_maxsize();
		}
		packet_start(SSH_SMSG_STDERR_DATA);
		packet_put_string(buffer_ptr(&stderr_buffer), len);
		packet_send();
		buffer_consume(&stderr_buffer, len);
		stderr_bytes += len;
	}
}

/*
 * Make packets from buffered stdout data, and buffer it for sending to the
 * client.
 */
void
make_packets_from_stdout_data(void)
{
	int len;

	/* Send buffered stdout data to the client. */
	while (buffer_len(&stdout_buffer) > 0 &&
	    packet_not_very_much_data_to_write()) {
		len = buffer_len(&stdout_buffer);
		if (packet_is_interactive()) {
			if (len > 512)
				len = 512;
		} else {
			/* Keep the packets at reasonable size. */
			if (len > packet_get_maxsize())
				len = packet_get_maxsize();
		}
		packet_start(SSH_SMSG_STDOUT_DATA);
		packet_put_string(buffer_ptr(&stdout_buffer), len);
		packet_send();
		buffer_consume(&stdout_buffer, len);
		stdout_bytes += len;
	}
}

/*
 * Sleep in select() until we can do something.  This will initialize the
 * select masks.  Upon return, the masks will indicate which descriptors
 * have data or can accept data.  Optionally, a maximum time can be specified
 * for the duration of the wait (0 = infinite).
 */
void
wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
    u_int max_time_milliseconds)
{
	struct timeval tv, *tvp;
	int ret;
	int client_alive_scheduled = 0;

	/*
	 * if using client_alive, set the max timeout accordingly, 
	 * and indicate that this particular timeout was for client
	 * alive by setting the client_alive_scheduled flag.
	 *
	 * this could be randomized somewhat to make traffic
	 * analysis more difficult, but we're not doing it yet.  
	 */
	if (max_time_milliseconds == 0 && options.client_alive_interval) {
	        client_alive_scheduled = 1;
		max_time_milliseconds = options.client_alive_interval * 1000;
	} else 
	        client_alive_scheduled = 0;

	/* When select fails we restart from here. */
retry_select:

	/* Allocate and update select() masks for channel descriptors. */
	channel_prepare_select(readsetp, writesetp, maxfdp, 0);

	if (compat20) {
		/* wrong: bad condition XXX */
		if (channel_not_very_much_buffered_data())
			FD_SET(connection_in, *readsetp);
	} else {
		/*
		 * Read packets from the client unless we have too much
		 * buffered stdin or channel data.
		 */
		if (buffer_len(&stdin_buffer) < buffer_high &&
		    channel_not_very_much_buffered_data())
			FD_SET(connection_in, *readsetp);
		/*
		 * If there is not too much data already buffered going to
		 * the client, try to get some more data from the program.
		 */
		if (packet_not_very_much_data_to_write()) {
			if (!fdout_eof)
				FD_SET(fdout, *readsetp);
			if (!fderr_eof)
				FD_SET(fderr, *readsetp);
		}
		/*
		 * If we have buffered data, try to write some of that data
		 * to the program.
		 */
		if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
			FD_SET(fdin, *writesetp);
	}

	/*
	 * If we have buffered packet data going to the client, mark that
	 * descriptor.
	 */
	if (packet_have_data_to_write())
		FD_SET(connection_out, *writesetp);

	/*
	 * If child has terminated and there is enough buffer space to read
	 * from it, then read as much as is available and exit.
	 */
	if (child_terminated && packet_not_very_much_data_to_write())
		if (max_time_milliseconds == 0 || client_alive_scheduled)
			max_time_milliseconds = 100;

	if (max_time_milliseconds == 0)
		tvp = NULL;
	else {
		tv.tv_sec = max_time_milliseconds / 1000;
		tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
		tvp = &tv;
	}
	if (tvp!=NULL)
		debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds);

	/* Wait for something to happen, or the timeout to expire. */
	ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);

	if (ret == -1) {
		if (errno != EINTR)
			error("select: %.100s", strerror(errno));
		else
			goto retry_select;
	}
	if (ret == 0 && client_alive_scheduled) {
		/* timeout, check to see how many we have had */
		client_alive_timeouts++;

		if (client_alive_timeouts > options.client_alive_count_max ) {
			packet_disconnect(
				"Timeout, your session not responding.");
		} else {
			/*
			 * send a bogus channel request with "wantreply" 
			 * we should get back a failure
			 */
			int id;
			
			id = channel_find_open();
			if (id != -1) {
				channel_request_start(id,
				  "keepalive@openssh.com", 1);
				packet_send();
			} else 
				packet_disconnect(
					"No open channels after timeout!");
		}
	} 
}

/*
 * Processes input from the client and the program.  Input data is stored
 * in buffers and processed later.
 */
void
process_input(fd_set * readset)
{
	int len;
	char buf[16384];

	/* Read and buffer any input data from the client. */
	if (FD_ISSET(connection_in, readset)) {
		len = read(connection_in, buf, sizeof(buf));
		if (len == 0) {
			verbose("Connection closed by remote host.");
			connection_closed = 1;
			if (compat20)
				return;
			fatal_cleanup();
		} else if (len < 0) {
			if (errno != EINTR && errno != EAGAIN) {
				verbose("Read error from remote host: %.100s", strerror(errno));
				fatal_cleanup();
			}
		} else {
			/* Buffer any received data. */
			packet_process_incoming(buf, len);
		}
	}
	if (compat20)
		return;

	/* Read and buffer any available stdout data from the program. */
	if (!fdout_eof && FD_ISSET(fdout, readset)) {
		len = read(fdout, buf, sizeof(buf));
		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
			/* do nothing */
		} else if (len <= 0) {
			fdout_eof = 1;
		} else {
			buffer_append(&stdout_buffer, buf, len);
			fdout_bytes += len;
		}
	}
	/* Read and buffer any available stderr data from the program. */
	if (!fderr_eof && FD_ISSET(fderr, readset)) {
		len = read(fderr, buf, sizeof(buf));
		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
			/* do nothing */
		} else if (len <= 0) {
			fderr_eof = 1;
		} else {
			buffer_append(&stderr_buffer, buf, len);
		}
	}
}

/*
 * Sends data from internal buffers to client program stdin.
 */
void
process_output(fd_set * writeset)
{
	struct termios tio;
	int len;

	/* Write buffered data to program stdin. */
	if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
		len = write(fdin, buffer_ptr(&stdin_buffer),
		    buffer_len(&stdin_buffer));
		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
			/* do nothing */
		} else if (len <= 0) {
#ifdef USE_PIPES
			close(fdin);
#else
			if (fdin != fdout)
				close(fdin);
			else
				shutdown(fdin, SHUT_WR); /* We will no longer send. */
#endif
			fdin = -1;
		} else {
			/* Successful write. */
			if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 &&
			    !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
				/*
				 * Simulate echo to reduce the impact of
				 * traffic analysis
				 */
				packet_send_ignore(len);
				packet_send();
			}
			/* Consume the data from the buffer. */
			buffer_consume(&stdin_buffer, len);
			/* Update the count of bytes written to the program. */
			stdin_bytes += len;
		}
	}
	/* Send any buffered packet data to the client. */
	if (FD_ISSET(connection_out, writeset))
		packet_write_poll();
}

/*
 * Wait until all buffered output has been sent to the client.
 * This is used when the program terminates.
 */
void
drain_output(void)
{
	/* Send any buffered stdout data to the client. */
	if (buffer_len(&stdout_buffer) > 0) {
		packet_start(SSH_SMSG_STDOUT_DATA);
		packet_put_string(buffer_ptr(&stdout_buffer),
				  buffer_len(&stdout_buffer));
		packet_send();
		/* Update the count of sent bytes. */
		stdout_bytes += buffer_len(&stdout_buffer);
	}
	/* Send any buffered stderr data to the client. */
	if (buffer_len(&stderr_buffer) > 0) {
		packet_start(SSH_SMSG_STDERR_DATA);
		packet_put_string(buffer_ptr(&stderr_buffer),
				  buffer_len(&stderr_buffer));
		packet_send();
		/* Update the count of sent bytes. */
		stderr_bytes += buffer_len(&stderr_buffer);
	}
	/* Wait until all buffered data has been written to the client. */
	packet_write_wait();
}

void
process_buffered_input_packets(void)
{
	dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL);
}

/*
 * Performs the interactive session.  This handles data transmission between
 * the client and the program.  Note that the notion of stdin, stdout, and
 * stderr in this function is sort of reversed: this function writes to
 * stdin (of the child program), and reads from stdout and stderr (of the
 * child program).
 */
void
server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
{
	fd_set *readset = NULL, *writeset = NULL;
	int max_fd;
	int wait_status;	/* Status returned by wait(). */
	pid_t wait_pid;		/* pid returned by wait(). */
	int waiting_termination = 0;	/* Have displayed waiting close message. */
	u_int max_time_milliseconds;
	u_int previous_stdout_buffer_bytes;
	u_int stdout_buffer_bytes;
	int type;

	debug("Entering interactive session.");

	/* Initialize the SIGCHLD kludge. */
	child_pid = pid;
	child_terminated = 0;
	signal(SIGCHLD, sigchld_handler);

	/* Initialize our global variables. */
	fdin = fdin_arg;
	fdout = fdout_arg;
	fderr = fderr_arg;

	/* nonblocking IO */
	set_nonblock(fdin);
	set_nonblock(fdout);
	/* we don't have stderr for interactive terminal sessions, see below */
	if (fderr != -1)
		set_nonblock(fderr);

	if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
		fdin_is_tty = 1;

	connection_in = packet_get_connection_in();
	connection_out = packet_get_connection_out();

	previous_stdout_buffer_bytes = 0;

	/* Set approximate I/O buffer size. */
	if (packet_is_interactive())
		buffer_high = 4096;
	else
		buffer_high = 64 * 1024;

	/* Initialize max_fd to the maximum of the known file descriptors. */
	max_fd = MAX(fdin, fdout);
	if (fderr != -1)
		max_fd = MAX(max_fd, fderr);
	max_fd = MAX(max_fd, connection_in);
	max_fd = MAX(max_fd, connection_out);

	/* Initialize Initialize buffers. */
	buffer_init(&stdin_buffer);
	buffer_init(&stdout_buffer);
	buffer_init(&stderr_buffer);

	/*
	 * If we have no separate fderr (which is the case when we have a pty
	 * - there we cannot make difference between data sent to stdout and
	 * stderr), indicate that we have seen an EOF from stderr.  This way
	 * we don\'t need to check the descriptor everywhere.
	 */
	if (fderr == -1)
		fderr_eof = 1;

	server_init_dispatch();

	/* Main loop of the server for the interactive session mode. */
	for (;;) {

		/* Process buffered packets from the client. */
		process_buffered_input_packets();

		/*
		 * If we have received eof, and there is no more pending
		 * input data, cause a real eof by closing fdin.
		 */
		if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
#ifdef USE_PIPES
			close(fdin);
#else
			if (fdin != fdout)
				close(fdin);
			else
				shutdown(fdin, SHUT_WR); /* We will no longer send. */
#endif
			fdin = -1;
		}
		/* Make packets from buffered stderr data to send to the client. */
		make_packets_from_stderr_data();

		/*
		 * Make packets from buffered stdout data to send to the
		 * client. If there is very little to send, this arranges to
		 * not send them now, but to wait a short while to see if we
		 * are getting more data. This is necessary, as some systems
		 * wake up readers from a pty after each separate character.
		 */
		max_time_milliseconds = 0;
		stdout_buffer_bytes = buffer_len(&stdout_buffer);
		if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
		    stdout_buffer_bytes != previous_stdout_buffer_bytes) {
			/* try again after a while */
			max_time_milliseconds = 10;
		} else {
			/* Send it now. */
			make_packets_from_stdout_data();
		}
		previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);

		/* Send channel data to the client. */
		if (packet_not_very_much_data_to_write())
			channel_output_poll();

		/*
		 * Bail out of the loop if the program has closed its output
		 * descriptors, and we have no more data to send to the
		 * client, and there is no pending buffered data.
		 */
		if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
		    buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
			if (!channel_still_open())
				break;
			if (!waiting_termination) {
				const char *s = "Waiting for forwarded connections to terminate...\r\n";
				char *cp;
				waiting_termination = 1;
				buffer_append(&stderr_buffer, s, strlen(s));

				/* Display list of open channels. */
				cp = channel_open_message();
				buffer_append(&stderr_buffer, cp, strlen(cp));
				xfree(cp);
			}
		}
		/* Sleep in select() until we can do something. */
		wait_until_can_do_something(&readset, &writeset, &max_fd,
		    max_time_milliseconds);

		/* Process any channel events. */
		channel_after_select(readset, writeset);

		/* Process input from the client and from program stdout/stderr. */
		process_input(readset);

		/* Process output to the client and to program stdin. */
		process_output(writeset);
	}
	if (readset)
		xfree(readset);
	if (writeset)
		xfree(writeset);

	/* Cleanup and termination code. */

	/* Wait until all output has been sent to the client. */
	drain_output();

	debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
	      stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);

	/* Free and clear the buffers. */
	buffer_free(&stdin_buffer);
	buffer_free(&stdout_buffer);
	buffer_free(&stderr_buffer);

	/* Close the file descriptors. */
	if (fdout != -1)
		close(fdout);
	fdout = -1;
	fdout_eof = 1;
	if (fderr != -1)
		close(fderr);
	fderr = -1;
	fderr_eof = 1;
	if (fdin != -1)
		close(fdin);
	fdin = -1;

	/* Stop listening for channels; this removes unix domain sockets. */
	channel_stop_listening();

	/* Wait for the child to exit.  Get its exit status. */
	wait_pid = wait(&wait_status);
	if (wait_pid == -1) {
		/*
		 * It is possible that the wait was handled by SIGCHLD
		 * handler.  This may result in either: this call
		 * returning with EINTR, or: this call returning ECHILD.
		 */
		if (child_terminated)
			wait_status = child_wait_status;
		else
			packet_disconnect("wait: %.100s", strerror(errno));
	} else {
		/* Check if it matches the process we forked. */
		if (wait_pid != pid)
			error("Strange, wait returned pid %d, expected %d",
			       wait_pid, pid);
	}

	/* We no longer want our SIGCHLD handler to be called. */
	signal(SIGCHLD, SIG_DFL);

	/* Check if it exited normally. */
	if (WIFEXITED(wait_status)) {
		/* Yes, normal exit.  Get exit status and send it to the client. */
		debug("Command exited with status %d.", WEXITSTATUS(wait_status));
		packet_start(SSH_SMSG_EXITSTATUS);
		packet_put_int(WEXITSTATUS(wait_status));
		packet_send();
		packet_write_wait();

		/*
		 * Wait for exit confirmation.  Note that there might be
		 * other packets coming before it; however, the program has
		 * already died so we just ignore them.  The client is
		 * supposed to respond with the confirmation when it receives
		 * the exit status.
		 */
		do {
			int plen;
			type = packet_read(&plen);
		}
		while (type != SSH_CMSG_EXIT_CONFIRMATION);

		debug("Received exit confirmation.");
		return;
	}
	/* Check if the program terminated due to a signal. */
	if (WIFSIGNALED(wait_status))
		packet_disconnect("Command terminated on signal %d.",
				  WTERMSIG(wait_status));

	/* Some weird exit cause.  Just exit. */
	packet_disconnect("wait returned status %04x.", wait_status);
	/* NOTREACHED */
}

void
server_loop2(void)
{
	fd_set *readset = NULL, *writeset = NULL;
	int rekeying = 0, max_fd, status;
	pid_t pid;

	debug("Entering interactive session for SSH2.");

	signal(SIGCHLD, sigchld_handler2);
	child_terminated = 0;
	connection_in = packet_get_connection_in();
	connection_out = packet_get_connection_out();

	max_fd = MAX(connection_in, connection_out);

	server_init_dispatch();

	for (;;) {
		process_buffered_input_packets();

		rekeying = (xxx_kex != NULL && !xxx_kex->done);

		if (!rekeying && packet_not_very_much_data_to_write())
			channel_output_poll();
		wait_until_can_do_something(&readset, &writeset, &max_fd,
		    rekeying);
		if (child_terminated) {
			while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
				session_close_by_pid(pid, status);
			child_terminated = 0;
		}
		if (!rekeying)
			channel_after_select(readset, writeset);
		process_input(readset);
		if (connection_closed)
			break;
		process_output(writeset);
	}
	if (readset)
		xfree(readset);
	if (writeset)
		xfree(writeset);

	signal(SIGCHLD, SIG_DFL);
	while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
		session_close_by_pid(pid, status);
	channel_stop_listening();
}

void
server_input_channel_failure(int type, int plen, void *ctxt)
{
	debug("Got CHANNEL_FAILURE for keepalive");
	/* 
         * reset timeout, since we got a sane answer from the client.
	 * even if this was generated by something other than
	 * the bogus CHANNEL_REQUEST we send for keepalives.
	 */
	client_alive_timeouts = 0; 
}


void
server_input_stdin_data(int type, int plen, void *ctxt)
{
	char *data;
	u_int data_len;

	/* Stdin data from the client.  Append it to the buffer. */
	/* Ignore any data if the client has closed stdin. */
	if (fdin == -1)
		return;
	data = packet_get_string(&data_len);
	packet_integrity_check(plen, (4 + data_len), type);
	buffer_append(&stdin_buffer, data, data_len);
	memset(data, 0, data_len);
	xfree(data);
}

void
server_input_eof(int type, int plen, void *ctxt)
{
	/*
	 * Eof from the client.  The stdin descriptor to the
	 * program will be closed when all buffered data has
	 * drained.
	 */
	debug("EOF received for stdin.");
	packet_integrity_check(plen, 0, type);
	stdin_eof = 1;
}

void
server_input_window_size(int type, int plen, void *ctxt)
{
	int row = packet_get_int();
	int col = packet_get_int();
	int xpixel = packet_get_int();
	int ypixel = packet_get_int();

	debug("Window change received.");
	packet_integrity_check(plen, 4 * 4, type);
	if (fdin != -1)
		pty_change_window_size(fdin, row, col, xpixel, ypixel);
}

Channel *
server_request_direct_tcpip(char *ctype)
{
	int sock, newch;
	char *target, *originator;
	int target_port, originator_port;

	target = packet_get_string(NULL);
	target_port = packet_get_int();
	originator = packet_get_string(NULL);
	originator_port = packet_get_int();
	packet_done();

	debug("server_request_direct_tcpip: originator %s port %d, target %s port %d",
	   originator, originator_port, target, target_port);

	/* XXX check permission */
	sock = channel_connect_to(target, target_port);
	xfree(target);
	xfree(originator);
	if (sock < 0)
		return NULL;
	newch = channel_new(ctype, SSH_CHANNEL_CONNECTING,
	    sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT,
	    CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1);
	return (newch >= 0) ? channel_lookup(newch) : NULL;
}

Channel *
server_request_session(char *ctype)
{
	int newch;

	debug("input_session_request");
	packet_done();
	/*
	 * A server session has no fd to read or write until a
	 * CHANNEL_REQUEST for a shell is made, so we set the type to
	 * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
	 * CHANNEL_REQUEST messages is registered.
	 */
	newch = channel_new(ctype, SSH_CHANNEL_LARVAL,
	    -1, -1, -1, 0, CHAN_SES_PACKET_DEFAULT,
	    0, xstrdup("server-session"), 1);
	if (session_open(newch) == 1) {
		channel_register_callback(newch, SSH2_MSG_CHANNEL_REQUEST,
		    session_input_channel_req, (void *)0);
		channel_register_cleanup(newch, session_close_by_channel);
		return channel_lookup(newch);
	} else {
		debug("session open failed, free channel %d", newch);
		channel_free(newch);
	}
	return NULL;
}

void
server_input_channel_open(int type, int plen, void *ctxt)
{
	Channel *c = NULL;
	char *ctype;
	u_int len;
	int rchan;
	int rmaxpack;
	int rwindow;

	ctype = packet_get_string(&len);
	rchan = packet_get_int();
	rwindow = packet_get_int();
	rmaxpack = packet_get_int();

	debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
	    ctype, rchan, rwindow, rmaxpack);

	if (strcmp(ctype, "session") == 0) {
		c = server_request_session(ctype);
	} else if (strcmp(ctype, "direct-tcpip") == 0) {
		c = server_request_direct_tcpip(ctype);
	}
	if (c != NULL) {
		debug("server_input_channel_open: confirm %s", ctype);
		c->remote_id = rchan;
		c->remote_window = rwindow;
		c->remote_maxpacket = rmaxpack;

		packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
		packet_put_int(c->remote_id);
		packet_put_int(c->self);
		packet_put_int(c->local_window);
		packet_put_int(c->local_maxpacket);
		packet_send();
	} else {
		debug("server_input_channel_open: failure %s", ctype);
		packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
		packet_put_int(rchan);
		packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
		packet_put_cstring("bla bla");
		packet_put_cstring("");
		packet_send();
	}
	xfree(ctype);
}

void
server_input_global_request(int type, int plen, void *ctxt)
{
	char *rtype;
	int want_reply;
	int success = 0;

	rtype = packet_get_string(NULL);
	want_reply = packet_get_char();
	debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);

	/* -R style forwarding */
	if (strcmp(rtype, "tcpip-forward") == 0) {
		struct passwd *pw;
		char *listen_address;
		u_short listen_port;

		pw = auth_get_user();
		if (pw == NULL)
			fatal("server_input_global_request: no user");
		listen_address = packet_get_string(NULL); /* XXX currently ignored */
		listen_port = (u_short)packet_get_int();
		debug("server_input_global_request: tcpip-forward listen %s port %d",
		    listen_address, listen_port);

		/* check permissions */
		if (!options.allow_tcp_forwarding ||
		    no_port_forwarding_flag ||
		    (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) {
			success = 0;
			packet_send_debug("Server has disabled port forwarding.");
		} else {
			/* Start listening on the port */
			success = channel_request_forwarding(
			    listen_address, listen_port,
			    /*unspec host_to_connect*/ "<unspec host>",
			    /*unspec port_to_connect*/ 0,
			    options.gateway_ports, /*remote*/ 1);
		}
		xfree(listen_address);
	}
	if (want_reply) {
		packet_start(success ?
		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
		packet_send();
		packet_write_wait();
	}
	xfree(rtype);
}

void
server_init_dispatch_20(void)
{
	debug("server_init_dispatch_20");
	dispatch_init(&dispatch_protocol_error);
	dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
	dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
	dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
	dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
	dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request);
	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
	/* client_alive */
	dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure);
	/* rekeying */
	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
}
void
server_init_dispatch_13(void)
{
	debug("server_init_dispatch_13");
	dispatch_init(NULL);
	dispatch_set(SSH_CMSG_EOF, &server_input_eof);
	dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
	dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
	dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
	dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
	dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
	dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
}
void
server_init_dispatch_15(void)
{
	server_init_dispatch_13();
	debug("server_init_dispatch_15");
	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
}
void
server_init_dispatch(void)
{
	if (compat20)
		server_init_dispatch_20();
	else if (compat13)
		server_init_dispatch_13();
	else
		server_init_dispatch_15();
}