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/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Created: Sun Sep 10 00:30:37 1995 ylo
 * Server main loop for handling the interactive session.
 */

#include "includes.h"
#include "xmalloc.h"
#include "ssh.h"
#include "packet.h"
#include "buffer.h"
#include "servconf.h"
#include "pty.h"

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 connection_in;	/* Connection to client (input). */
static int connection_out;	/* Connection to client (output). */
static unsigned int buffer_high;/* "Soft" max buffer size. */
static int max_fd;		/* Max file descriptor number for select(). */

/*
 * 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 int 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 
sigchld_handler(int sig)
{
	int save_errno = errno;
	int 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;
}

/*
 * Process any buffered packets that have been received from the client.
 */
void 
process_buffered_input_packets()
{
	int type;
	char *data;
	unsigned int data_len;
	int row, col, xpixel, ypixel;
	int payload_len;

	/* Process buffered packets from the client. */
	while ((type = packet_read_poll(&payload_len)) != SSH_MSG_NONE) {
		switch (type) {
		case SSH_CMSG_STDIN_DATA:
			/* Stdin data from the client.  Append it to the buffer. */
			/* Ignore any data if the client has closed stdin. */
			if (fdin == -1)
				break;
			data = packet_get_string(&data_len);
			packet_integrity_check(payload_len, (4 + data_len), type);
			buffer_append(&stdin_buffer, data, data_len);
			memset(data, 0, data_len);
			xfree(data);
			break;

		case SSH_CMSG_EOF:
			/*
			 * 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(payload_len, 0, type);
			stdin_eof = 1;
			break;

		case SSH_CMSG_WINDOW_SIZE:
			debug("Window change received.");
			packet_integrity_check(payload_len, 4 * 4, type);
			row = packet_get_int();
			col = packet_get_int();
			xpixel = packet_get_int();
			ypixel = packet_get_int();
			if (fdin != -1)
				pty_change_window_size(fdin, row, col, xpixel, ypixel);
			break;

		case SSH_MSG_PORT_OPEN:
			debug("Received port open request.");
			channel_input_port_open(payload_len);
			break;

		case SSH_MSG_CHANNEL_OPEN_CONFIRMATION:
			debug("Received channel open confirmation.");
			packet_integrity_check(payload_len, 4 + 4, type);
			channel_input_open_confirmation();
			break;

		case SSH_MSG_CHANNEL_OPEN_FAILURE:
			debug("Received channel open failure.");
			packet_integrity_check(payload_len, 4, type);
			channel_input_open_failure();
			break;

		case SSH_MSG_CHANNEL_DATA:
			channel_input_data(payload_len);
			break;

		case SSH_MSG_CHANNEL_CLOSE:
			debug("Received channel close.");
			packet_integrity_check(payload_len, 4, type);
			channel_input_close();
			break;

		case SSH_MSG_CHANNEL_CLOSE_CONFIRMATION:
			debug("Received channel close confirmation.");
			packet_integrity_check(payload_len, 4, type);
			channel_input_close_confirmation();
			break;

		default:
			/*
			 * In this phase, any unexpected messages cause a
			 * protocol error.  This is to ease debugging; also,
			 * since no confirmations are sent messages,
			 * unprocessed unknown messages could cause strange
			 * problems.  Any compatible protocol extensions must
			 * be negotiated before entering the interactive
			 * session.
			 */
			packet_disconnect("Protocol error during session: type %d",
					  type);
		}
	}
}

/*
 * Make packets from buffered stderr data, and buffer it for sending
 * to the client.
 */
void 
make_packets_from_stderr_data()
{
	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()
{
	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 * readset, fd_set * writeset,
			    unsigned int max_time_milliseconds)
{
	struct timeval tv, *tvp;
	int ret;

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

	/* Initialize select() masks. */
	FD_ZERO