Vendor import of OpenSSH.

1 files changed, 952 insertions, 0 deletions

diff --git a/crypto/openssh/clientloop.c b/crypto/openssh/clientloop.c
new file mode 100644
index 0000000..59dad3d
--- /dev/null
+++ b/crypto/openssh/clientloop.c
@@ -0,0 +1,952 @@
+/*
+ * 
+ * clientloop.c
+ * 
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * 
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * 
+ * 
+ * Created: Sat Sep 23 12:23:57 1995 ylo
+ * 
+ * The main loop for the interactive session (client side).
+ * 
+ */
+
+#include "includes.h"
+RCSID("$Id: clientloop.c,v 1.14 1999/12/06 20:15:26 deraadt Exp $");
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "packet.h"
+#include "buffer.h"
+#include "authfd.h"
+#include "readconf.h"
+
+/* Flag indicating that stdin should be redirected from /dev/null. */
+extern int stdin_null_flag;
+
+/*
+ * Name of the host we are connecting to.  This is the name given on the
+ * command line, or the HostName specified for the user-supplied name in a
+ * configuration file.
+ */
+extern char *host;
+
+/*
+ * Flag to indicate that we have received a window change signal which has
+ * not yet been processed.  This will cause a message indicating the new
+ * window size to be sent to the server a little later.  This is volatile
+ * because this is updated in a signal handler.
+ */
+static volatile int received_window_change_signal = 0;
+
+/* Terminal modes, as saved by enter_raw_mode. */
+static struct termios saved_tio;
+
+/*
+ * Flag indicating whether we are in raw mode.  This is used by
+ * enter_raw_mode and leave_raw_mode.
+ */
+static int in_raw_mode = 0;
+
+/* Flag indicating whether the user\'s terminal is in non-blocking mode. */
+static int in_non_blocking_mode = 0;
+
+/* Common data for the client loop code. */
+static int escape_pending;	/* Last character was the escape character */
+static int last_was_cr;		/* Last character was a newline. */
+static int exit_status;		/* Used to store the exit status of the command. */
+static int stdin_eof;		/* EOF has been encountered on standard error. */
+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 unsigned int buffer_high;/* Soft max buffer size. */
+static int max_fd;		/* Maximum file descriptor number in select(). */
+static int connection_in;	/* Connection to server (input). */
+static int connection_out;	/* Connection to server (output). */
+static unsigned long stdin_bytes, stdout_bytes, stderr_bytes;
+static int quit_pending;	/* Set to non-zero to quit the client loop. */
+static int escape_char;		/* Escape character. */
+
+/* Returns the user\'s terminal to normal mode if it had been put in raw mode. */
+
+void 
+leave_raw_mode()
+{
+	if (!in_raw_mode)
+		return;
+	in_raw_mode = 0;
+	if (tcsetattr(fileno(stdin), TCSADRAIN, &saved_tio) < 0)
+		perror("tcsetattr");
+
+	fatal_remove_cleanup((void (*) (void *)) leave_raw_mode, NULL);
+}
+
+/* Puts the user\'s terminal in raw mode. */
+
+void 
+enter_raw_mode()
+{
+	struct termios tio;
+
+	if (tcgetattr(fileno(stdin), &tio) < 0)
+		perror("tcgetattr");
+	saved_tio = tio;
+	tio.c_iflag |= IGNPAR;
+	tio.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
+	tio.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
+#ifdef IEXTEN
+	tio.c_lflag &= ~IEXTEN;
+#endif				/* IEXTEN */
+	tio.c_oflag &= ~OPOST;
+	tio.c_cc[VMIN] = 1;
+	tio.c_cc[VTIME] = 0;
+	if (tcsetattr(fileno(stdin), TCSADRAIN, &tio) < 0)
+		perror("tcsetattr");
+	in_raw_mode = 1;
+
+	fatal_add_cleanup((void (*) (void *)) leave_raw_mode, NULL);
+}
+
+/* Restores stdin to blocking mode. */
+
+void 
+leave_non_blocking()
+{
+	if (in_non_blocking_mode) {
+		(void) fcntl(fileno(stdin), F_SETFL, 0);
+		in_non_blocking_mode = 0;
+		fatal_remove_cleanup((void (*) (void *)) leave_non_blocking, NULL);
+	}
+}
+
+/* Puts stdin terminal in non-blocking mode. */
+
+void 
+enter_non_blocking()
+{
+	in_non_blocking_mode = 1;
+	(void) fcntl(fileno(stdin), F_SETFL, O_NONBLOCK);
+	fatal_add_cleanup((void (*) (void *)) leave_non_blocking, NULL);
+}
+
+/*
+ * Signal handler for the window change signal (SIGWINCH).  This just sets a
+ * flag indicating that the window has changed.
+ */
+
+void 
+window_change_handler(int sig)
+{
+	received_window_change_signal = 1;
+	signal(SIGWINCH, window_change_handler);
+}
+
+/*
+ * Signal handler for signals that cause the program to terminate.  These
+ * signals must be trapped to restore terminal modes.
+ */
+
+void 
+signal_handler(int sig)
+{
+	if (in_raw_mode)
+		leave_raw_mode();
+	if (in_non_blocking_mode)
+		leave_non_blocking();
+	channel_stop_listening();
+	packet_close();
+	fatal("Killed by signal %d.", sig);
+}
+
+/*
+ * Returns current time in seconds from Jan 1, 1970 with the maximum
+ * available resolution.
+ */
+
+double 
+get_current_time()
+{
+	struct timeval tv;
+	gettimeofday(&tv, NULL);
+	return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
+}
+
+/*
+ * This is called when the interactive is entered.  This checks if there is
+ * an EOF coming on stdin.  We must check this explicitly, as select() does
+ * not appear to wake up when redirecting from /dev/null.
+ */
+
+void 
+client_check_initial_eof_on_stdin()
+{
+	int len;
+	char buf[1];
+
+	/*
+	 * If standard input is to be "redirected from /dev/null", we simply
+	 * mark that we have seen an EOF and send an EOF message to the
+	 * server. Otherwise, we try to read a single character; it appears
+	 * that for some files, such /dev/null, select() never wakes up for
+	 * read for this descriptor, which means that we never get EOF.  This
+	 * way we will get the EOF if stdin comes from /dev/null or similar.
+	 */
+	if (stdin_null_flag) {
+		/* Fake EOF on stdin. */
+		debug("Sending eof.");
+		stdin_eof = 1;
+		packet_start(SSH_CMSG_EOF);
+		packet_send();
+	} else {
+		enter_non_blocking();
+
+		/* Check for immediate EOF on stdin. */
+		len = read(fileno(stdin), buf, 1);
+		if (len == 0) {
+			/* EOF.  Record that we have seen it and send EOF to server. */
+			debug("Sending eof.");
+			stdin_eof = 1;
+			packet_start(SSH_CMSG_EOF);
+			packet_send();
+		} else if (len > 0) {
+			/*
+			 * Got data.  We must store the data in the buffer,
+			 * and also process it as an escape character if
+			 * appropriate.
+			 */
+			if ((unsigned char) buf[0] == escape_char)
+				escape_pending = 1;
+			else {
+				buffer_append(&stdin_buffer, buf, 1);
+				stdin_bytes += 1;
+			}
+		}
+		leave_non_blocking();
+	}
+}
+
+/*
+ * Get packets from the connection input buffer, and process them as long as
+ * there are packets available.
+ */
+
+void 
+client_process_buffered_input_packets()
+{
+	int type;
+	char *data;
+	unsigned int data_len;
+	int payload_len;
+
+	/* Process any buffered packets from the server. */
+	while (!quit_pending &&
+	       (type = packet_read_poll(&payload_len)) != SSH_MSG_NONE) {
+		switch (type) {
+
+		case SSH_SMSG_STDOUT_DATA:
+			data = packet_get_string(&data_len);
+			packet_integrity_check(payload_len, 4 + data_len, type);
+			buffer_append(&stdout_buffer, data, data_len);
+			stdout_bytes += data_len;
+			memset(data, 0, data_len);
+			xfree(data);
+			break;
+
+		case SSH_SMSG_STDERR_DATA:
+			data = packet_get_string(&data_len);
+			packet_integrity_check(payload_len, 4 + data_len, type);
+			buffer_append(&stderr_buffer, data, data_len);
+			stdout_bytes += data_len;
+			memset(data, 0, data_len);
+			xfree(data);
+			break;
+
+		case SSH_SMSG_EXITSTATUS:
+			packet_integrity_check(payload_len, 4, type);
+			exit_status = packet_get_int();
+			/* Acknowledge the exit. */
+			packet_start(SSH_CMSG_EXIT_CONFIRMATION);
+			packet_send();
+			/*
+			 * Must wait for packet to be sent since we are
+			 * exiting the loop.
+			 */
+			packet_write_wait();
+			/* Flag that we want to exit. */
+			quit_pending = 1;
+			break;
+
+		case SSH_SMSG_X11_OPEN:
+			x11_input_open(payload_len);
+			break;
+
+		case SSH_MSG_PORT_OPEN:
+			channel_input_port_open(payload_len);
+			break;
+
+		case SSH_SMSG_AGENT_OPEN:
+			packet_integrity_check(payload_len, 4, type);
+			auth_input_open_request();
+			break;
+
+		case SSH_MSG_CHANNEL_OPEN_CONFIRMATION:
+			packet_integrity_check(payload_len, 4 + 4, type);
+			channel_input_open_confirmation();
+			break;
+
+		case SSH_MSG_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:
+			packet_integrity_check(payload_len, 4, type);
+			channel_input_close();
+			break;
+
+		case SSH_MSG_CHANNEL_CLOSE_CONFIRMATION:
+			packet_integrity_check(payload_len, 4, type);
+			channel_input_close_confirmation();
+			break;
+
+		default:
+			/*
+			 * Any unknown packets received during the actual
+			 * session cause the session to terminate.  This is
+			 * intended to make debugging easier since no
+			 * confirmations are sent.  Any compatible protocol
+			 * extensions must be negotiated during the
+			 * preparatory phase.
+			 */
+			packet_disconnect("Protocol error during session: type %d",
+					  type);
+		}
+	}
+}
+
+/*
+ * Make packets from buffered stdin data, and buffer them for sending to the
+ * connection.
+ */
+
+void 
+client_make_packets_from_stdin_data()
+{
+	unsigned int len;
+
+	/* Send buffered stdin data to the server. */
+	while (buffer_len(&stdin_buffer) > 0 &&
+	       packet_not_very_much_data_to_write()) {
+		len = buffer_len(&stdin_buffer);
+		/* Keep the packets at reasonable size. */
+		if (len > packet_get_maxsize())
+			len = packet_get_maxsize();
+		packet_start(SSH_CMSG_STDIN_DATA);
+		packet_put_string(buffer_ptr(&stdin_buffer), len);
+		packet_send();
+		buffer_consume(&stdin_buffer, len);
+		/* If we have a pending EOF, send it now. */
+		if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
+			packet_start(SSH_CMSG_EOF);
+			packet_send();
+		}
+	}
+}
+
+/*
+ * Checks if the client window has changed, and sends a packet about it to
+ * the server if so.  The actual change is detected elsewhere (by a software
+ * interrupt on Unix); this just checks the flag and sends a message if
+ * appropriate.
+ */
+
+void 
+client_check_window_change()
+{
+	/* Send possible window change message to the server. */
+	if (received_window_change_signal) {
+		struct winsize ws;
+
+		/* Clear the window change indicator. */
+		received_window_change_signal = 0;
+
+		/* Read new window size. */
+		if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) >= 0) {
+			/* Successful, send the packet now. */
+			packet_start(SSH_CMSG_WINDOW_SIZE);
+			packet_put_int(ws.ws_row);
+			packet_put_int(ws.ws_col);
+			packet_put_int(ws.ws_xpixel);
+			packet_put_int(ws.ws_ypixel);
+			packet_send();
+		}
+	}
+}
+
+/*
+ * Waits until the client can do something (some data becomes available on
+ * one of the file descriptors).
+ */
+
+void 
+client_wait_until_can_do_something(fd_set * readset, fd_set * writeset)
+{
+	/* Initialize select masks. */
+	FD_ZERO(readset);
+
+	/* Read from the connection, unless our buffers are full. */
+	if (buffer_len(&stdout_buffer) < buffer_high &&
+	    buffer_len(&stderr_buffer) < buffer_high &&
+	    channel_not_very_much_buffered_data())
+		FD_SET(connection_in, readset);
+
+	/*
+	 * Read from stdin, unless we have seen EOF or have very much
+	 * buffered data to send to the server.
+	 */
+	if (!stdin_eof && packet_not_very_much_data_to_write())
+		FD_SET(fileno(stdin), readset);
+
+	FD_ZERO(writeset);
+
+	/* Add any selections by the channel mechanism. */
+	channel_prepare_select(readset, writeset);
+
+	/* Select server connection if have data to write to the server. */
+	if (packet_have_data_to_write())
+		FD_SET(connection_out, writeset);
+
+	/* Select stdout if have data in buffer. */
+	if (buffer_len(&stdout_buffer) > 0)
+		FD_SET(fileno(stdout), writeset);
+
+	/* Select stderr if have data in buffer. */
+	if (buffer_len(&stderr_buffer) > 0)
+		FD_SET(fileno(stderr), writeset);
+
+	/* Update maximum file descriptor number, if appropriate. */
+	if (channel_max_fd() > max_fd)
+		max_fd = channel_max_fd();
+
+	/*
+	 * Wait for something to happen.  This will suspend the process until
+	 * some selected descriptor can be read, written, or has some other
+	 * event pending. Note: if you want to implement SSH_MSG_IGNORE
+	 * messages to fool traffic analysis, this might be the place to do
+	 * it: just have a random timeout for the select, and send a random
+	 * SSH_MSG_IGNORE packet when the timeout expires.
+	 */
+
+	if (select(max_fd + 1, readset, writeset, NULL, NULL) < 0) {
+		char buf[100];
+		/* Some systems fail to clear these automatically. */
+		FD_ZERO(readset);
+		FD_ZERO(writeset);
+		if (errno == EINTR)
+			return;
+		/* Note: we might still have data in the buffers. */
+		snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
+		buffer_append(&stderr_buffer, buf, strlen(buf));
+		stderr_bytes += strlen(buf);
+		quit_pending = 1;
+	}
+}
+
+void 
+client_suspend_self()
+{
+	struct winsize oldws, newws;
+
+	/* Flush stdout and stderr buffers. */
+	if (buffer_len(&stdout_buffer) > 0)
+		atomicio(write, fileno(stdout), buffer_ptr(&stdout_buffer),
+		    buffer_len(&stdout_buffer));
+	if (buffer_len(&stderr_buffer) > 0)
+		atomicio(write, fileno(stderr), buffer_ptr(&stderr_buffer),
+		    buffer_len(&stderr_buffer));
+
+	leave_raw_mode();
+
+	/*
+	 * Free (and clear) the buffer to reduce the amount of data that gets
+	 * written to swap.
+	 */
+	buffer_free(&stdin_buffer);
+	buffer_free(&stdout_buffer);
+	buffer_free(&stderr_buffer);
+
+	/* Save old window size. */
+	ioctl(fileno(stdin), TIOCGWINSZ, &oldws);
+
+	/* Send the suspend signal to the program itself. */
+	kill(getpid(), SIGTSTP);
+
+	/* Check if the window size has changed. */
+	if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 &&
+	    (oldws.ws_row != newws.ws_row ||
+	     oldws.ws_col != newws.ws_col ||
+	     oldws.ws_xpixel != newws.ws_xpixel ||
+	     oldws.ws_ypixel != newws.ws_ypixel))
+		received_window_change_signal = 1;
+
+	/* OK, we have been continued by the user. Reinitialize buffers. */
+	buffer_init(&stdin_buffer);
+	buffer_init(&stdout_buffer);
+	buffer_init(&stderr_buffer);
+
+	enter_raw_mode();
+}
+
+void 
+client_process_input(fd_set * readset)
+{
+	int len, pid;
+	char buf[8192], *s;
+
+	/*
+	 * Read input from the server, and add any such data to the buffer of
+	 * the packet subsystem.
+	 */
+	if (FD_ISSET(connection_in, readset)) {
+		/* Read as much as possible. */
+		len = read(connection_in, buf, sizeof(buf));
+		if (len == 0) {
+			/* Received EOF.  The remote host has closed the connection. */
+			snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n",
+				 host);
+			buffer_append(&stderr_buffer, buf, strlen(buf));
+			stderr_bytes += strlen(buf);
+			quit_pending = 1;
+			return;
+		}
+		/*
+		 * There is a kernel bug on Solaris that causes select to
+		 * sometimes wake up even though there is no data available.
+		 */
+		if (len < 0 && errno == EAGAIN)
+			len = 0;
+
+		if (len < 0) {
+			/* An error has encountered.  Perhaps there is a network problem. */
+			snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n",
+				 host, strerror(errno));
+			buffer_append(&stderr_buffer, buf, strlen(buf));
+			stderr_bytes += strlen(buf);
+			quit_pending = 1;
+			return;
+		}
+		packet_process_incoming(buf, len);
+	}
+	/* Read input from stdin. */
+	if (FD_ISSET(fileno(stdin), readset)) {
+		/* Read as much as possible. */
+		len = read(fileno(stdin), buf, sizeof(buf));
+		if (len <= 0) {
+			/*
+			 * Received EOF or error.  They are treated
+			 * similarly, except that an error message is printed
+			 * if it was an error condition.
+			 */
+			if (len < 0) {
+				snprintf(buf, sizeof buf, "read: %.100s\r\n", strerror(errno));
+				buffer_append(&stderr_buffer, buf, strlen(buf));
+				stderr_bytes += strlen(buf);
+			}
+			/* Mark that we have seen EOF. */
+			stdin_eof = 1;
+			/*
+			 * Send an EOF message to the server unless there is
+			 * data in the buffer.  If there is data in the
+			 * buffer, no message will be sent now.  Code
+			 * elsewhere will send the EOF when the buffer
+			 * becomes empty if stdin_eof is set.
+			 */
+			if (buffer_len(&stdin_buffer) == 0) {
+				packet_start(SSH_CMSG_EOF);
+				packet_send();
+			}
+		} else if (escape_char == -1) {
+			/*
+			 * Normal successful read, and no escape character.
+			 * Just append the data to buffer.
+			 */
+			buffer_append(&stdin_buffer, buf, len);
+			stdin_bytes += len;
+		} else {
+			/*
+			 * Normal, successful read.  But we have an escape character
+			 * and have to process the characters one by one.
+			 */
+			unsigned int i;
+			for (i = 0; i < len; i++) {
+				unsigned char ch;
+				/* Get one character at a time. */
+				ch = buf[i];
+
+				if (escape_pending) {
+					/* We have previously seen an escape character. */
+					/* Clear the flag now. */
+					escape_pending = 0;
+					/* Process the escaped character. */
+					switch (ch) {
+					case '.':
+						/* Terminate the connection. */
+						snprintf(buf, sizeof buf, "%c.\r\n", escape_char);
+						buffer_append(&stderr_buffer, buf, strlen(buf));
+						stderr_bytes += strlen(buf);
+						quit_pending = 1;
+						return;
+
+					case 'Z' - 64:
+						/* Suspend the program. */
+						/* Print a message to that effect to the user. */
+						snprintf(buf, sizeof buf, "%c^Z\r\n", escape_char);
+						buffer_append(&stderr_buffer, buf, strlen(buf));
+						stderr_bytes += strlen(buf);
+
+						/* Restore terminal modes and suspend. */
+						client_suspend_self();
+
+						/* We have been continued. */
+						continue;
+
+					case '&':
+						/*
+						 * Detach the program (continue to serve connections,
+						 * but put in background and no more new connections).
+						 */
+						if (!stdin_eof) {
+							/*
+							 * Sending SSH_CMSG_EOF alone does not always appear
+							 * to be enough.  So we try to send an EOF character
+							 * first.
+							 */
+							packet_start(SSH_CMSG_STDIN_DATA);
+							packet_put_string("\004", 1);
+							packet_send();
+							/* Close stdin. */
+							stdin_eof = 1;
+							if (buffer_len(&stdin_buffer) == 0) {
+								packet_start(SSH_CMSG_EOF);
+								packet_send();
+							}
+						}
+						/* Restore tty modes. */
+						leave_raw_mode();
+
+						/* Stop listening for new connections. */
+						channel_stop_listening();
+
+						printf("%c& [backgrounded]\n", escape_char);
+
+						/* Fork into background. */
+						pid = fork();
+						if (pid < 0) {
+							error("fork: %.100s", strerror(errno));
+							continue;
+						}
+						if (pid != 0) {	/* This is the parent. */
+							/* The parent just exits. */
+							exit(0);
+						}
+						/* The child continues serving connections. */
+						continue;
+
+					case '?':
+						snprintf(buf, sizeof buf,
+"%c?\r\n\
+Supported escape sequences:\r\n\
+~.  - terminate connection\r\n\
+~^Z - suspend ssh\r\n\
+~#  - list forwarded connections\r\n\
+~&  - background ssh (when waiting for connections to terminate)\r\n\
+~?  - this message\r\n\
+~~  - send the escape character by typing it twice\r\n\
+(Note that escapes are only recognized immediately after newline.)\r\n",
+							 escape_char);
+						buffer_append(&stderr_buffer, buf, strlen(buf));
+						continue;
+
+					case '#':
+						snprintf(buf, sizeof buf, "%c#\r\n", escape_char);
+						buffer_append(&stderr_buffer, buf, strlen(buf));
+						s = channel_open_message();
+						buffer_append(&stderr_buffer, s, strlen(s));
+						xfree(s);
+						continue;
+
+					default:
+						if (ch != escape_char) {
+							/*
+							 * Escape character followed by non-special character.
+							 * Append both to the input buffer.
+							 */
+							buf[0] = escape_char;
+							buf[1] = ch;
+							buffer_append(&stdin_buffer, buf, 2);
+							stdin_bytes += 2;
+							continue;
+						}
+						/*
+						 * Note that escape character typed twice
+						 * falls through here; the latter gets processed
+						 * as a normal character below.
+						 */
+						break;
+					}
+				} else {
+					/*
+					 * The previous character was not an escape char. Check if this
+					 * is an escape.
+					 */
+					if (last_was_cr && ch == escape_char) {
+						/* It is. Set the flag and continue to next character. */
+						escape_pending = 1;
+						continue;
+					}
+				}
+
+				/*
+				 * Normal character.  Record whether it was a newline,
+				 * and append it to the buffer.
+				 */
+				last_was_cr = (ch == '\r' || ch == '\n');
+				buf[0] = ch;
+				buffer_append(&stdin_buffer, buf, 1);
+				stdin_bytes += 1;
+				continue;
+			}
+		}
+	}
+}
+
+void 
+client_process_output(fd_set * writeset)
+{
+	int len;
+	char buf[100];
+
+	/* Write buffered output to stdout. */
+	if (FD_ISSET(fileno(stdout), writeset)) {
+		/* Write as much data as possible. */
+		len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
+		    buffer_len(&stdout_buffer));
+		if (len <= 0) {
+			if (errno == EAGAIN)
+				len = 0;
+			else {
+				/*
+				 * An error or EOF was encountered.  Put an
+				 * error message to stderr buffer.
+				 */
+				snprintf(buf, sizeof buf, "write stdout: %.50s\r\n", strerror(errno));
+				buffer_append(&stderr_buffer, buf, strlen(buf));
+				stderr_bytes += strlen(buf);
+				quit_pending = 1;
+				return;
+			}
+		}
+		/* Consume printed data from the buffer. */
+		buffer_consume(&stdout_buffer, len);
+	}
+	/* Write buffered output to stderr. */
+	if (FD_ISSET(fileno(stderr), writeset)) {
+		/* Write as much data as possible. */
+		len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
+		    buffer_len(&stderr_buffer));
+		if (len <= 0) {
+			if (errno == EAGAIN)
+				len = 0;
+			else {
+				/* EOF or error, but can't even print error message. */
+				quit_pending = 1;
+				return;
+			}
+		}
+		/* Consume printed characters from the buffer. */
+		buffer_consume(&stderr_buffer, len);
+	}
+}
+
+/*
+ * Implements the interactive session with the server.  This is called after
+ * the user has been authenticated, and a command has been started on the
+ * remote host.  If escape_char != -1, it is the character used as an escape
+ * character for terminating or suspending the session.
+ */
+
+int 
+client_loop(int have_pty, int escape_char_arg)
+{
+	extern Options options;
+	double start_time, total_time;
+	int len;
+	char buf[100];
+
+	debug("Entering interactive session.");
+
+	start_time = get_current_time();
+
+	/* Initialize variables. */
+	escape_pending = 0;
+	last_was_cr = 1;
+	exit_status = -1;
+	stdin_eof = 0;
+	buffer_high = 64 * 1024;
+	connection_in = packet_get_connection_in();
+	connection_out = packet_get_connection_out();
+	max_fd = connection_in;
+	if (connection_out > max_fd)
+		max_fd = connection_out;
+	stdin_bytes = 0;
+	stdout_bytes = 0;
+	stderr_bytes = 0;
+	quit_pending = 0;
+	escape_char = escape_char_arg;
+
+	/* Initialize buffers. */
+	buffer_init(&stdin_buffer);
+	buffer_init(&stdout_buffer);
+	buffer_init(&stderr_buffer);
+
+	/* Set signal handlers to restore non-blocking mode.  */
+	signal(SIGINT, signal_handler);
+	signal(SIGQUIT, signal_handler);
+	signal(SIGTERM, signal_handler);
+	signal(SIGPIPE, SIG_IGN);
+	if (have_pty)
+		signal(SIGWINCH, window_change_handler);
+
+	if (have_pty)
+		enter_raw_mode();
+
+	/* Check if we should immediately send of on stdin. */
+	client_check_initial_eof_on_stdin();
+
+	/* Main loop of the client for the interactive session mode. */
+	while (!quit_pending) {
+		fd_set readset, writeset;
+
+		/* Process buffered packets sent by the server. */
+		client_process_buffered_input_packets();
+
+		/*
+		 * Make packets of buffered stdin data, and buffer them for
+		 * sending to the server.
+		 */
+		client_make_packets_from_stdin_data();
+
+		/*
+		 * Make packets from buffered channel data, and buffer them
+		 * for sending to the server.
+		 */
+		if (packet_not_very_much_data_to_write())
+			channel_output_poll();
+
+		/*
+		 * Check if the window size has changed, and buffer a message
+		 * about it to the server if so.
+		 */
+		client_check_window_change();
+
+		if (quit_pending)
+			break;
+
+		/*
+		 * Wait until we have something to do (something becomes
+		 * available on one of the descriptors).
+		 */
+		client_wait_until_can_do_something(&readset, &writeset);
+
+		if (quit_pending)
+			break;
+
+		/* Do channel operations. */
+		channel_after_select(&readset, &writeset);
+
+		/*
+		 * Process input from the connection and from stdin. Buffer
+		 * any data that is available.
+		 */
+		client_process_input(&readset);
+
+		/*
+		 * Process output to stdout and stderr.   Output to the
+		 * connection is processed elsewhere (above).
+		 */
+		client_process_output(&writeset);
+
+		/* Send as much buffered packet data as possible to the sender. */
+		if (FD_ISSET(connection_out, &writeset))
+			packet_write_poll();
+	}
+
+	/* Terminate the session. */
+
+	/* Stop watching for window change. */
+	if (have_pty)
+		signal(SIGWINCH, SIG_DFL);
+
+	/* Stop listening for connections. */
+	channel_stop_listening();
+
+	/*
+	 * In interactive mode (with pseudo tty) display a message indicating
+	 * that the connection has been closed.
+	 */
+	if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
+		snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host);
+		buffer_append(&stderr_buffer, buf, strlen(buf));
+		stderr_bytes += strlen(buf);
+	}
+	/* Output any buffered data for stdout. */
+	while (buffer_len(&stdout_buffer) > 0) {
+		len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
+		    buffer_len(&stdout_buffer));
+		if (len <= 0) {
+			error("Write failed flushing stdout buffer.");
+			break;
+		}
+		buffer_consume(&stdout_buffer, len);
+	}
+
+	/* Output any buffered data for stderr. */
+	while (buffer_len(&stderr_buffer) > 0) {
+		len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
+		    buffer_len(&stderr_buffer));
+		if (len <= 0) {
+			error("Write failed flushing stderr buffer.");
+			break;
+		}
+		buffer_consume(&stderr_buffer, len);
+	}
+
+	if (have_pty)
+		leave_raw_mode();
+
+	/* Clear and free any buffers. */
+	memset(buf, 0, sizeof(buf));
+	buffer_free(&stdin_buffer);
+	buffer_free(&stdout_buffer);
+	buffer_free(&stderr_buffer);
+
+	/* Report bytes transferred, and transfer rates. */
+	total_time = get_current_time() - start_time;
+	debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds",
+	      stdin_bytes, stdout_bytes, stderr_bytes, total_time);
+	if (total_time > 0)
+		debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f",
+		      stdin_bytes / total_time, stdout_bytes / total_time,
+		      stderr_bytes / total_time);
+
+	/* Return the exit status of the program. */
+	debug("Exit status %d", exit_status);
+	return exit_status;
+}