Merge changes I934c73d4,I28cdc9a0,I9e734da9,I3c079d86

* changes:
  UPSTREAM: depend
  UPSTREAM: upstream: avoid possible NULL deref; from Pedro Martelletto
  Revert "upstream: fix compilation with DEBUG_KEXDH; bz#3160 ok dtucker@"
  Merge upstream-master into master

1 files changed, 403 insertions, 839 deletions

diff --git a/serverloop.c b/serverloop.c
index 306ac36b..340b19a5 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.178 2015/02/20 22:17:21 djm Exp $ */
+/* $OpenBSD: serverloop.c,v 1.222 2020/01/30 07:21:38 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -37,7 +37,6 @@
 
 #include "includes.h"
 
-#include <sys/param.h>	/* MIN MAX */
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <sys/socket.h>
@@ -50,6 +49,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <pwd.h>
+#include <limits.h>
 #include <signal.h>
 #include <string.h>
 #include <termios.h>
@@ -59,7 +59,7 @@
 #include "openbsd-compat/sys-queue.h"
 #include "xmalloc.h"
 #include "packet.h"
-#include "buffer.h"
+#include "sshbuf.h"
 #include "log.h"
 #include "misc.h"
 #include "servconf.h"
@@ -67,9 +67,8 @@
 #include "sshpty.h"
 #include "channels.h"
 #include "compat.h"
-#include "ssh1.h"
 #include "ssh2.h"
-#include "key.h"
+#include "sshkey.h"
 #include "cipher.h"
 #include "kex.h"
 #include "hostfile.h"
@@ -78,34 +77,15 @@
 #include "dispatch.h"
 #include "auth-options.h"
 #include "serverloop.h"
-#include "roaming.h"
 #include "ssherr.h"
 
 extern ServerOptions options;
 
 /* XXX */
 extern Authctxt *the_authctxt;
+extern struct sshauthopt *auth_opts;
 extern int use_privsep;
 
-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. */
 static int no_more_sessions = 0; /* Disallow further sessions. */
 
 /*
@@ -119,7 +99,21 @@ static volatile sig_atomic_t child_terminated = 0;	/* The child has terminated.
 static volatile sig_atomic_t received_sigterm = 0;
 
 /* prototypes */
-static void server_init_dispatch(void);
+static void server_init_dispatch(struct ssh *);
+
+/* requested tunnel forwarding interface(s), shared with session.c */
+char *tun_fwd_ifnames = NULL;
+
+/* returns 1 if bind to specified port by specified user is permitted */
+static int
+bind_permitted(int port, uid_t uid)
+{
+	if (use_privsep)
+		return 1; /* allow system to decide */
+	if (port < IPPORT_RESERVED && uid != 0)
+		return 0;
+	return 1;
+}
 
 /*
  * we write to this pipe if a SIGCHLD is caught in order to avoid
@@ -129,7 +123,7 @@ static int notify_pipe[2];
 static void
 notify_setup(void)
 {
-	if (pipe(notify_pipe) < 0) {
+	if (pipe(notify_pipe) == -1) {
 		error("pipe(notify_pipe) failed %s", strerror(errno));
 	} else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) ||
 	    (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) {
@@ -163,7 +157,7 @@ notify_done(fd_set *readset)
 
 	if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
 		while (read(notify_pipe[0], &c, 1) != -1)
-			debug2("notify_done: reading");
+			debug2("%s: reading", __func__);
 }
 
 /*ARGSUSED*/
@@ -172,9 +166,6 @@ sigchld_handler(int sig)
 {
 	int save_errno = errno;
 	child_terminated = 1;
-#ifndef _UNICOS
-	mysignal(SIGCHLD, sigchld_handler);
-#endif
 	notify_parent();
 	errno = save_errno;
 }
@@ -186,72 +177,18 @@ sigterm_handler(int sig)
 	received_sigterm = sig;
 }
 
-/*
- * Make packets from buffered stderr data, and buffer it for sending
- * to the client.
- */
-static void
-make_packets_from_stderr_data(void)
-{
-	u_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.
- */
 static void
-make_packets_from_stdout_data(void)
+client_alive_check(struct ssh *ssh)
 {
-	u_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;
-	}
-}
-
-static void
-client_alive_check(void)
-{
-	int channel_id;
+	char remote_id[512];
+	int r, channel_id;
 
 	/* timeout, check to see how many we have had */
-	if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
-		logit("Timeout, client not responding.");
+	if (options.client_alive_count_max > 0 &&
+	    ssh_packet_inc_alive_timeouts(ssh) >
+	    options.client_alive_count_max) {
+		sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
+		logit("Timeout, client not responding from %s", remote_id);
 		cleanup_exit(255);
 	}
 
@@ -259,14 +196,18 @@ client_alive_check(void)
 	 * send a bogus global/channel request with "wantreply",
 	 * we should get back a failure
 	 */
-	if ((channel_id = channel_find_open()) == -1) {
-		packet_start(SSH2_MSG_GLOBAL_REQUEST);
-		packet_put_cstring("keepalive@openssh.com");
-		packet_put_char(1);	/* boolean: want reply */
+	if ((channel_id = channel_find_open(ssh)) == -1) {
+		if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com"))
+		    != 0 ||
+		    (r = sshpkt_put_u8(ssh, 1)) != 0) /* boolean: want reply */
+			fatal("%s: %s", __func__, ssh_err(r));
 	} else {
-		channel_request_start(channel_id, "keepalive@openssh.com", 1);
+		channel_request_start(ssh, channel_id,
+		    "keepalive@openssh.com", 1);
 	}
-	packet_send();
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
 }
 
 /*
@@ -276,22 +217,25 @@ client_alive_check(void)
  * for the duration of the wait (0 = infinite).
  */
 static void
-wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
-    u_int *nallocp, u_int64_t max_time_milliseconds)
+wait_until_can_do_something(struct ssh *ssh,
+    int connection_in, int connection_out,
+    fd_set **readsetp, fd_set **writesetp, int *maxfdp,
+    u_int *nallocp, u_int64_t max_time_ms)
 {
 	struct timeval tv, *tvp;
 	int ret;
 	time_t minwait_secs = 0;
 	int client_alive_scheduled = 0;
-	int program_alive_scheduled = 0;
+	/* time we last heard from the client OR sent a keepalive */
+	static time_t last_client_time;
 
 	/* Allocate and update select() masks for channel descriptors. */
-	channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
-	    &minwait_secs, 0);
+	channel_prepare_select(ssh, readsetp, writesetp, maxfdp,
+	    nallocp, &minwait_secs);
 
+	/* XXX need proper deadline system for rekey/client alive */
 	if (minwait_secs != 0)
-		max_time_milliseconds = MIN(max_time_milliseconds,
-		    (u_int)minwait_secs * 1000);
+		max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000);
 
 	/*
 	 * if using client_alive, set the max timeout accordingly,
@@ -301,67 +245,43 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 	 * this could be randomized somewhat to make traffic
 	 * analysis more difficult, but we're not doing it yet.
 	 */
-	if (compat20 &&
-	    max_time_milliseconds == 0 && options.client_alive_interval) {
-		client_alive_scheduled = 1;
-		max_time_milliseconds =
-		    (u_int64_t)options.client_alive_interval * 1000;
+	if (options.client_alive_interval) {
+		uint64_t keepalive_ms =
+		    (uint64_t)options.client_alive_interval * 1000;
+
+		if (max_time_ms == 0 || max_time_ms > keepalive_ms) {
+			max_time_ms = keepalive_ms;
+			client_alive_scheduled = 1;
+		}
 	}
 
-	if (compat20) {
 #if 0
-		/* wrong: bad condition XXX */
-		if (channel_not_very_much_buffered_data())
+	/* wrong: bad condition XXX */
+	if (channel_not_very_much_buffered_data())
 #endif
-		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()) {
-			program_alive_scheduled = child_terminated;
-			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);
-	}
+	FD_SET(connection_in, *readsetp);
 	notify_prepare(*readsetp);
 
 	/*
 	 * If we have buffered packet data going to the client, mark that
 	 * descriptor.
 	 */
-	if (packet_have_data_to_write())
+	if (ssh_packet_have_data_to_write(ssh))
 		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 (child_terminated && ssh_packet_not_very_much_data_to_write(ssh))
+		if (max_time_ms == 0 || client_alive_scheduled)
+			max_time_ms = 100;
 
-	if (max_time_milliseconds == 0)
+	if (max_time_ms == 0)
 		tvp = NULL;
 	else {
-		tv.tv_sec = max_time_milliseconds / 1000;
-		tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
+		tv.tv_sec = max_time_ms / 1000;
+		tv.tv_usec = 1000 * (max_time_ms % 1000);
 		tvp = &tv;
 	}
 
@@ -373,14 +293,19 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 		memset(*writesetp, 0, *nallocp);
 		if (errno != EINTR)
 			error("select: %.100s", strerror(errno));
-	} else {
-		if (ret == 0 && client_alive_scheduled)
-			client_alive_check();
-		if (!compat20 && program_alive_scheduled && fdin_is_tty) {
-			if (!fdout_eof)
-				FD_SET(fdout, *readsetp);
-			if (!fderr_eof)
-				FD_SET(fderr, *readsetp);
+	} else if (client_alive_scheduled) {
+		time_t now = monotime();
+
+		/*
+		 * If the select timed out, or returned for some other reason
+		 * but we haven't heard from the client in time, send keepalive.
+		 */
+		if (ret == 0 || (last_client_time != 0 && last_client_time +
+		    options.client_alive_interval <= now)) {
+			client_alive_check(ssh);
+			last_client_time = now;
+		} else if (FD_ISSET(connection_in, *readsetp)) {
+			last_client_time = now;
 		}
 	}
 
@@ -391,415 +316,64 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
  * Processes input from the client and the program.  Input data is stored
  * in buffers and processed later.
  */
-static void
-process_input(fd_set *readset)
+static int
+process_input(struct ssh *ssh, fd_set *readset, int connection_in)
 {
-	int len;
+	int r, len;
 	char buf[16384];
 
 	/* Read and buffer any input data from the client. */
 	if (FD_ISSET(connection_in, readset)) {
-		int cont = 0;
-		len = roaming_read(connection_in, buf, sizeof(buf), &cont);
+		len = read(connection_in, buf, sizeof(buf));
 		if (len == 0) {
-			if (cont)
-				return;
-			verbose("Connection closed by %.100s",
-			    get_remote_ipaddr());
-			connection_closed = 1;
-			if (compat20)
-				return;
-			cleanup_exit(255);
-		} else if (len < 0) {
+			verbose("Connection closed by %.100s port %d",
+			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+			return -1;
+		} else if (len == -1) {
 			if (errno != EINTR && errno != EAGAIN &&
 			    errno != EWOULDBLOCK) {
 				verbose("Read error from remote host "
-				    "%.100s: %.100s",
-				    get_remote_ipaddr(), strerror(errno));
+				    "%.100s port %d: %.100s",
+				    ssh_remote_ipaddr(ssh),
+				    ssh_remote_port(ssh), strerror(errno));
 				cleanup_exit(255);
 			}
 		} 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)) {
-		errno = 0;
-		len = read(fdout, buf, sizeof(buf));
-		if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
-		    errno == EWOULDBLOCK) && !child_terminated))) {
-			/* do nothing */
-#ifndef PTY_ZEROREAD
-		} else if (len <= 0) {
-#else
-		} else if ((!isatty(fdout) && len <= 0) ||
-		    (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) {
-#endif
-			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)) {
-		errno = 0;
-		len = read(fderr, buf, sizeof(buf));
-		if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
-		    errno == EWOULDBLOCK) && !child_terminated))) {
-			/* do nothing */
-#ifndef PTY_ZEROREAD
-		} else if (len <= 0) {
-#else
-		} else if ((!isatty(fderr) && len <= 0) ||
-		    (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) {
-#endif
-			fderr_eof = 1;
-		} else {
-			buffer_append(&stderr_buffer, buf, len);
+			if ((r = ssh_packet_process_incoming(ssh, buf, len))
+			    != 0)
+				fatal("%s: ssh_packet_process_incoming: %s",
+				    __func__, ssh_err(r));
 		}
 	}
+	return 0;
 }
 
 /*
  * Sends data from internal buffers to client program stdin.
  */
 static void
-process_output(fd_set *writeset)
+process_output(struct ssh *ssh, fd_set *writeset, int connection_out)
 {
-	struct termios tio;
-	u_char *data;
-	u_int dlen;
-	int len;
-
-	/* Write buffered data to program stdin. */
-	if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
-		data = buffer_ptr(&stdin_buffer);
-		dlen = buffer_len(&stdin_buffer);
-		len = write(fdin, data, dlen);
-		if (len < 0 &&
-		    (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) {
-			/* do nothing */
-		} else if (len <= 0) {
-			if (fdin != fdout)
-				close(fdin);
-			else
-				shutdown(fdin, SHUT_WR); /* We will no longer send. */
-			fdin = -1;
-		} else {
-			/* Successful write. */
-			if (fdin_is_tty && dlen >= 1 && data[0] != '\r' &&
-			    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;
+	int r;
+
+	/* Send any buffered packet data to the client. */
+	if (FD_ISSET(connection_out, writeset)) {
+		if ((r = ssh_packet_write_poll(ssh)) != 0) {
+			sshpkt_fatal(ssh, r, "%s: ssh_packet_write_poll",
+			    __func__);
 		}
 	}
-	/* 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.
- */
 static void
-drain_output(void)
+process_buffered_input_packets(struct ssh *ssh)
 {
-	/* 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();
+	ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL);
 }
 
 static void
-process_buffered_input_packets(void)
-{
-	dispatch_run(DISPATCH_NONBLOCK, NULL, active_state);
-}
-
-/*
- * 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 = 0;
-	u_int nalloc = 0;
-	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_int64_t 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_terminated = 0;
-	mysignal(SIGCHLD, sigchld_handler);
-
-	if (!use_privsep) {
-		signal(SIGTERM, sigterm_handler);
-		signal(SIGINT, sigterm_handler);
-		signal(SIGQUIT, sigterm_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();
-
-	notify_setup();
-
-	previous_stdout_buffer_bytes = 0;
-
-	/* Set approximate I/O buffer size. */
-	if (packet_is_interactive())
-		buffer_high = 4096;
-	else
-		buffer_high = 64 * 1024;
-
-#if 0
-	/* Initialize max_fd to the maximum of the known file descriptors. */
-	max_fd = MAX(connection_in, connection_out);
-	max_fd = MAX(max_fd, fdin);
-	max_fd = MAX(max_fd, fdout);
-	if (fderr != -1)
-		max_fd = MAX(max_fd, fderr);
-#endif
-
-	/* 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) {
-			if (fdin != fdout)
-				close(fdin);
-			else
-				shutdown(fdin, SHUT_WR); /* We will no longer send. */
-			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));
-				free(cp);
-			}
-		}
-		max_fd = MAX(connection_in, connection_out);
-		max_fd = MAX(max_fd, fdin);
-		max_fd = MAX(max_fd, fdout);
-		max_fd = MAX(max_fd, fderr);
-		max_fd = MAX(max_fd, notify_pipe[0]);
-
-		/* Sleep in select() until we can do something. */
-		wait_until_can_do_something(&readset, &writeset, &max_fd,
-		    &nalloc, max_time_milliseconds);
-
-		if (received_sigterm) {
-			logit("Exiting on signal %d", (int)received_sigterm);
-			/* Clean up sessions, utmp, etc. */
-			cleanup_exit(255);
-		}
-
-		/* 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);
-	}
-	free(readset);
-	free(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;
-
-	channel_free_all();
-
-	/* We no longer want our SIGCHLD handler to be called. */
-	mysignal(SIGCHLD, SIG_DFL);
-
-	while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
-		if (errno != EINTR)
-			packet_disconnect("wait: %.100s", strerror(errno));
-	if (wait_pid != pid)
-		error("Strange, wait returned pid %ld, expected %ld",
-		    (long)wait_pid, (long)pid);
-
-	/* 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 {
-			type = packet_read();
-		}
-		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 */
-}
-
-static void
-collect_children(void)
+collect_children(struct ssh *ssh)
 {
 	pid_t pid;
 	sigset_t oset, nset;
@@ -812,56 +386,58 @@ collect_children(void)
 	if (child_terminated) {
 		debug("Received SIGCHLD.");
 		while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
-		    (pid < 0 && errno == EINTR))
+		    (pid == -1 && errno == EINTR))
 			if (pid > 0)
-				session_close_by_pid(pid, status);
+				session_close_by_pid(ssh, pid, status);
 		child_terminated = 0;
 	}
 	sigprocmask(SIG_SETMASK, &oset, NULL);
 }
 
 void
-server_loop2(Authctxt *authctxt)
+server_loop2(struct ssh *ssh, Authctxt *authctxt)
 {
 	fd_set *readset = NULL, *writeset = NULL;
-	int rekeying = 0, max_fd;
-	u_int nalloc = 0;
+	int max_fd;
+	u_int nalloc = 0, connection_in, connection_out;
 	u_int64_t rekey_timeout_ms = 0;
 
 	debug("Entering interactive session for SSH2.");
 
-	mysignal(SIGCHLD, sigchld_handler);
+	ssh_signal(SIGCHLD, sigchld_handler);
 	child_terminated = 0;
-	connection_in = packet_get_connection_in();
-	connection_out = packet_get_connection_out();
+	connection_in = ssh_packet_get_connection_in(ssh);
+	connection_out = ssh_packet_get_connection_out(ssh);
 
 	if (!use_privsep) {
-		signal(SIGTERM, sigterm_handler);
-		signal(SIGINT, sigterm_handler);
-		signal(SIGQUIT, sigterm_handler);
+		ssh_signal(SIGTERM, sigterm_handler);
+		ssh_signal(SIGINT, sigterm_handler);
+		ssh_signal(SIGQUIT, sigterm_handler);
 	}
 
 	notify_setup();
 
-	max_fd = MAX(connection_in, connection_out);
-	max_fd = MAX(max_fd, notify_pipe[0]);
+	max_fd = MAXIMUM(connection_in, connection_out);
+	max_fd = MAXIMUM(max_fd, notify_pipe[0]);
 
-	server_init_dispatch();
+	server_init_dispatch(ssh);
 
 	for (;;) {
-		process_buffered_input_packets();
-
-		rekeying = (active_state->kex != NULL && !active_state->kex->done);
-
-		if (!rekeying && packet_not_very_much_data_to_write())
-			channel_output_poll();
-		if (options.rekey_interval > 0 && compat20 && !rekeying)
-			rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
-		else
+		process_buffered_input_packets(ssh);
+
+		if (!ssh_packet_is_rekeying(ssh) &&
+		    ssh_packet_not_very_much_data_to_write(ssh))
+			channel_output_poll(ssh);
+		if (options.rekey_interval > 0 &&
+		    !ssh_packet_is_rekeying(ssh)) {
+			rekey_timeout_ms = ssh_packet_get_rekey_timeout(ssh) *
+			    1000;
+		} else {
 			rekey_timeout_ms = 0;
+		}
 
-		wait_until_can_do_something(&readset, &writeset, &max_fd,
-		    &nalloc, rekey_timeout_ms);
+		wait_until_can_do_something(ssh, connection_in, connection_out,
+		    &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms);
 
 		if (received_sigterm) {
 			logit("Exiting on signal %d", (int)received_sigterm);
@@ -869,34 +445,27 @@ server_loop2(Authctxt *authctxt)
 			cleanup_exit(255);
 		}
 
-		collect_children();
-		if (!rekeying) {
-			channel_after_select(readset, writeset);
-			if (packet_need_rekeying()) {
-				debug("need rekeying");
-				active_state->kex->done = 0;
-				kex_send_kexinit(active_state);
-			}
-		}
-		process_input(readset);
-		if (connection_closed)
+		collect_children(ssh);
+		if (!ssh_packet_is_rekeying(ssh))
+			channel_after_select(ssh, readset, writeset);
+		if (process_input(ssh, readset, connection_in) < 0)
 			break;
-		process_output(writeset);
+		process_output(ssh, writeset, connection_out);
 	}
-	collect_children();
+	collect_children(ssh);
 
 	free(readset);
 	free(writeset);
 
 	/* free all channels, no more reads and writes */
-	channel_free_all();
+	channel_free_all(ssh);
 
 	/* free remaining sessions, e.g. remove wtmp entries */
-	session_destroy_all(NULL);
+	session_destroy_all(ssh, NULL);
 }
 
 static int
-server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
+server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh)
 {
 	debug("Got %d/%u for keepalive", type, seq);
 	/*
@@ -904,109 +473,88 @@ server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
 	 * even if this was generated by something other than
 	 * the bogus CHANNEL_REQUEST we send for keepalives.
 	 */
-	packet_set_alive_timeouts(0);
-	return 0;
-}
-
-static int
-server_input_stdin_data(int type, u_int32_t seq, 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 0;
-	data = packet_get_string(&data_len);
-	packet_check_eom();
-	buffer_append(&stdin_buffer, data, data_len);
-	explicit_bzero(data, data_len);
-	free(data);
-	return 0;
-}
-
-static int
-server_input_eof(int type, u_int32_t seq, 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_check_eom();
-	stdin_eof = 1;
-	return 0;
-}
-
-static int
-server_input_window_size(int type, u_int32_t seq, void *ctxt)
-{
-	u_int row = packet_get_int();
-	u_int col = packet_get_int();
-	u_int xpixel = packet_get_int();
-	u_int ypixel = packet_get_int();
-
-	debug("Window change received.");
-	packet_check_eom();
-	if (fdin != -1)
-		pty_change_window_size(fdin, row, col, xpixel, ypixel);
+	ssh_packet_set_alive_timeouts(ssh, 0);
 	return 0;
 }
 
 static Channel *
-server_request_direct_tcpip(void)
+server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg)
 {
 	Channel *c = NULL;
-	char *target, *originator;
-	u_short 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_check_eom();
-
-	debug("server_request_direct_tcpip: originator %s port %d, target %s "
-	    "port %d", originator, originator_port, target, target_port);
+	char *target = NULL, *originator = NULL;
+	u_int target_port = 0, originator_port = 0;
+	int r;
+
+	if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &target_port)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	if (target_port > 0xFFFF) {
+		error("%s: invalid target port", __func__);
+		*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+		goto out;
+	}
+	if (originator_port > 0xFFFF) {
+		error("%s: invalid originator port", __func__);
+		*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+		goto out;
+	}
+
+	debug("%s: originator %s port %u, target %s port %u", __func__,
+	    originator, originator_port, target, target_port);
 
 	/* XXX fine grained permissions */
 	if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
-	    !no_port_forwarding_flag) {
-		c = channel_connect_to_port(target, target_port,
-		    "direct-tcpip", "direct-tcpip");
+	    auth_opts->permit_port_forwarding_flag &&
+	    !options.disable_forwarding) {
+		c = channel_connect_to_port(ssh, target, target_port,
+		    "direct-tcpip", "direct-tcpip", reason, errmsg);
 	} else {
 		logit("refused local port forward: "
 		    "originator %s port %d, target %s port %d",
 		    originator, originator_port, target, target_port);
+		if (reason != NULL)
+			*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
 	}
 
+ out:
 	free(originator);
 	free(target);
-
 	return c;
 }
 
 static Channel *
-server_request_direct_streamlocal(void)
+server_request_direct_streamlocal(struct ssh *ssh)
 {
 	Channel *c = NULL;
-	char *target, *originator;
-	u_short originator_port;
+	char *target = NULL, *originator = NULL;
+	u_int originator_port = 0;
+	struct passwd *pw = the_authctxt->pw;
+	int r;
+
+	if (pw == NULL || !the_authctxt->valid)
+		fatal("%s: no/invalid user", __func__);
 
-	target = packet_get_string(NULL);
-	originator = packet_get_string(NULL);
-	originator_port = packet_get_int();
-	packet_check_eom();
+	if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	if (originator_port > 0xFFFF) {
+		error("%s: invalid originator port", __func__);
+		goto out;
+	}
 
-	debug("server_request_direct_streamlocal: originator %s port %d, target %s",
+	debug("%s: originator %s port %d, target %s", __func__,
 	    originator, originator_port, target);
 
 	/* XXX fine grained permissions */
 	if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
-	    !no_port_forwarding_flag) {
-		c = channel_connect_to_path(target,
+	    auth_opts->permit_port_forwarding_flag &&
+	    !options.disable_forwarding && (pw->pw_uid == 0 || use_privsep)) {
+		c = channel_connect_to_path(ssh, target,
 		    "direct-streamlocal@openssh.com", "direct-streamlocal");
 	} else {
 		logit("refused streamlocal port forward: "
@@ -1014,69 +562,94 @@ server_request_direct_streamlocal(void)
 		    originator, originator_port, target);
 	}
 
+out:
 	free(originator);
 	free(target);
-
 	return c;
 }
 
 static Channel *
-server_request_tun(void)
+server_request_tun(struct ssh *ssh)
 {
 	Channel *c = NULL;
-	int mode, tun;
-	int sock;
+	u_int mode, tun;
+	int r, sock;
+	char *tmp, *ifname = NULL;
 
-	mode = packet_get_int();
+	if ((r = sshpkt_get_u32(ssh, &mode)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse mode", __func__);
 	switch (mode) {
 	case SSH_TUNMODE_POINTOPOINT:
 	case SSH_TUNMODE_ETHERNET:
 		break;
 	default:
-		packet_send_debug("Unsupported tunnel device mode.");
+		ssh_packet_send_debug(ssh, "Unsupported tunnel device mode.");
 		return NULL;
 	}
 	if ((options.permit_tun & mode) == 0) {
-		packet_send_debug("Server has rejected tunnel device "
+		ssh_packet_send_debug(ssh, "Server has rejected tunnel device "
 		    "forwarding");
 		return NULL;
 	}
 
-	tun = packet_get_int();
-	if (forced_tun_device != -1) {
-		if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
+	if ((r = sshpkt_get_u32(ssh, &tun)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse device", __func__);
+	if (tun > INT_MAX) {
+		debug("%s: invalid tun", __func__);
+		goto done;
+	}
+	if (auth_opts->force_tun_device != -1) {
+		if (tun != SSH_TUNID_ANY &&
+		    auth_opts->force_tun_device != (int)tun)
 			goto done;
-		tun = forced_tun_device;
+		tun = auth_opts->force_tun_device;
 	}
-	sock = tun_open(tun, mode);
+	sock = tun_open(tun, mode, &ifname);
 	if (sock < 0)
 		goto done;
-	c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
+	debug("Tunnel forwarding using interface %s", ifname);
+
+	c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1,
 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
 	c->datagram = 1;
 #if defined(SSH_TUN_FILTER)
 	if (mode == SSH_TUNMODE_POINTOPOINT)
-		channel_register_filter(c->self, sys_tun_infilter,
+		channel_register_filter(ssh, c->self, sys_tun_infilter,
 		    sys_tun_outfilter, NULL, NULL);
 #endif
 
+	/*
+	 * Update the list of names exposed to the session
+	 * XXX remove these if the tunnels are closed (won't matter
+	 * much if they are already in the environment though)
+	 */
+	tmp = tun_fwd_ifnames;
+	xasprintf(&tun_fwd_ifnames, "%s%s%s",
+	    tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames,
+	    tun_fwd_ifnames == NULL ? "" : ",",
+	    ifname);
+	free(tmp);
+	free(ifname);
+
  done:
 	if (c == NULL)
-		packet_send_debug("Failed to open the tunnel device.");
+		ssh_packet_send_debug(ssh, "Failed to open the tunnel device.");
 	return c;
 }
 
 static Channel *
-server_request_session(void)
+server_request_session(struct ssh *ssh)
 {
 	Channel *c;
+	int r;
 
 	debug("input_session_request");
-	packet_check_eom();
+	if ((r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
 
 	if (no_more_sessions) {
-		packet_disconnect("Possible attack: attempt to open a session "
-		    "after additional sessions disabled");
+		ssh_packet_disconnect(ssh, "Possible attack: attempt to open a "
+		    "session after additional sessions disabled");
 	}
 
 	/*
@@ -1085,79 +658,84 @@ server_request_session(void)
 	 * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
 	 * CHANNEL_REQUEST messages is registered.
 	 */
-	c = channel_new("session", SSH_CHANNEL_LARVAL,
+	c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL,
 	    -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
 	    0, "server-session", 1);
 	if (session_open(the_authctxt, c->self) != 1) {
 		debug("session open failed, free channel %d", c->self);
-		channel_free(c);
+		channel_free(ssh, c);
 		return NULL;
 	}
-	channel_register_cleanup(c->self, session_close_by_channel, 0);
+	channel_register_cleanup(ssh, c->self, session_close_by_channel, 0);
 	return c;
 }
 
 static int
-server_input_channel_open(int type, u_int32_t seq, void *ctxt)
+server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
 {
 	Channel *c = NULL;
-	char *ctype;
-	int rchan;
-	u_int rmaxpack, rwindow, len;
-
-	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",
+	char *ctype = NULL;
+	const char *errmsg = NULL;
+	int r, reason = SSH2_OPEN_CONNECT_FAILED;
+	u_int rchan = 0, rmaxpack = 0, rwindow = 0;
+
+	if ((r = sshpkt_get_cstring(ssh, &ctype, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	debug("%s: ctype %s rchan %u win %u max %u", __func__,
 	    ctype, rchan, rwindow, rmaxpack);
 
 	if (strcmp(ctype, "session") == 0) {
-		c = server_request_session();
+		c = server_request_session(ssh);
 	} else if (strcmp(ctype, "direct-tcpip") == 0) {
-		c = server_request_direct_tcpip();
+		c = server_request_direct_tcpip(ssh, &reason, &errmsg);
 	} else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
-		c = server_request_direct_streamlocal();
+		c = server_request_direct_streamlocal(ssh);
 	} else if (strcmp(ctype, "tun@openssh.com") == 0) {
-		c = server_request_tun();
+		c = server_request_tun(ssh);
 	}
 	if (c != NULL) {
-		debug("server_input_channel_open: confirm %s", ctype);
+		debug("%s: confirm %s", __func__, ctype);
 		c->remote_id = rchan;
+		c->have_remote_id = 1;
 		c->remote_window = rwindow;
 		c->remote_maxpacket = rmaxpack;
 		if (c->type != SSH_CHANNEL_CONNECTING) {
-			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();
+			if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
+			    (r = sshpkt_send(ssh)) != 0) {
+				sshpkt_fatal(ssh, r,
+				    "%s: send open confirm", __func__);
+			}
 		}
 	} 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);
-		if (!(datafellows & SSH_BUG_OPENFAILURE)) {
-			packet_put_cstring("open failed");
-			packet_put_cstring("");
+		debug("%s: failure %s", __func__, ctype);
+		if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, reason)) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, errmsg ? errmsg : "open failed")) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0) {
+			sshpkt_fatal(ssh, r,
+			    "%s: send open failure", __func__);
 		}
-		packet_send();
 	}
 	free(ctype);
 	return 0;
 }
 
 static int
-server_input_hostkeys_prove(struct sshbuf **respp)
+server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp)
 {
-	struct ssh *ssh = active_state; /* XXX */
 	struct sshbuf *resp = NULL;
 	struct sshbuf *sigbuf = NULL;
 	struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
-	int r, ndx, success = 0;
+	int r, ndx, kexsigtype, use_kexsigtype, success = 0;
 	const u_char *blob;
 	u_char *sig = 0;
 	size_t blen, slen;
@@ -1165,6 +743,8 @@ server_input_hostkeys_prove(struct sshbuf **respp)
 	if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
 		fatal("%s: sshbuf_new", __func__);
 
+	kexsigtype = sshkey_type_plain(
+	    sshkey_type_from_name(ssh->kex->hostkey_alg));
 	while (ssh_packet_remaining(ssh) > 0) {
 		sshkey_free(key);
 		key = NULL;
@@ -1195,13 +775,20 @@ server_input_hostkeys_prove(struct sshbuf **respp)
 		sshbuf_reset(sigbuf);
 		free(sig);
 		sig = NULL;
+		/*
+		 * For RSA keys, prefer to use the signature type negotiated
+		 * during KEX to the default (SHA1).
+		 */
+		use_kexsigtype = kexsigtype == KEY_RSA &&
+		    sshkey_type_plain(key->type) == KEY_RSA;
 		if ((r = sshbuf_put_cstring(sigbuf,
 		    "hostkeys-prove-00@openssh.com")) != 0 ||
 		    (r = sshbuf_put_string(sigbuf,
 		    ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
 		    (r = sshkey_puts(key, sigbuf)) != 0 ||
-		    (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
-		    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), 0)) != 0 ||
+		    (r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
+		    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf),
+		    use_kexsigtype ? ssh->kex->hostkey_alg : NULL)) != 0 ||
 		    (r = sshbuf_put_string(resp, sig, slen)) != 0) {
 			error("%s: couldn't prepare signature: %s",
 			    __func__, ssh_err(r));
@@ -1221,198 +808,175 @@ server_input_hostkeys_prove(struct sshbuf **respp)
 }
 
 static int
-server_input_global_request(int type, u_int32_t seq, void *ctxt)
+server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
 {
-	char *rtype;
-	int want_reply;
+	char *rtype = NULL;
+	u_char want_reply = 0;
 	int r, success = 0, allocated_listen_port = 0;
+	u_int port = 0;
 	struct sshbuf *resp = NULL;
+	struct passwd *pw = the_authctxt->pw;
+	struct Forward fwd;
+
+	memset(&fwd, 0, sizeof(fwd));
+	if (pw == NULL || !the_authctxt->valid)
+		fatal("%s: no/invalid user", __func__);
 
-	rtype = packet_get_string(NULL);
-	want_reply = packet_get_char();
-	debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
+	if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
+	    (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	debug("%s: rtype %s want_reply %d", __func__, rtype, want_reply);
 
 	/* -R style forwarding */
 	if (strcmp(rtype, "tcpip-forward") == 0) {
-		struct passwd *pw;
-		struct Forward fwd;
-
-		pw = the_authctxt->pw;
-		if (pw == NULL || !the_authctxt->valid)
-			fatal("server_input_global_request: no/invalid user");
-		memset(&fwd, 0, sizeof(fwd));
-		fwd.listen_host = packet_get_string(NULL);
-		fwd.listen_port = (u_short)packet_get_int();
-		debug("server_input_global_request: tcpip-forward listen %s port %d",
-		    fwd.listen_host, fwd.listen_port);
-
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
+		    (r = sshpkt_get_u32(ssh, &port)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse tcpip-forward", __func__);
+		debug("%s: tcpip-forward listen %s port %u", __func__,
+		    fwd.listen_host, port);
+		if (port <= INT_MAX)
+			fwd.listen_port = (int)port;
 		/* check permissions */
-		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
-		    no_port_forwarding_flag ||
-		    (!want_reply && fwd.listen_port == 0)
-#ifndef NO_IPPORT_RESERVED_CONCEPT
-		    || (fwd.listen_port != 0 && fwd.listen_port < IPPORT_RESERVED &&
-		    pw->pw_uid != 0)
-#endif
-		    ) {
+		if (port > INT_MAX ||
+		    (options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
+		    !auth_opts->permit_port_forwarding_flag ||
+		    options.disable_forwarding ||
+		    (!want_reply && fwd.listen_port == 0) ||
+		    (fwd.listen_port != 0 &&
+		     !bind_permitted(fwd.listen_port, pw->pw_uid))) {
 			success = 0;
-			packet_send_debug("Server has disabled port forwarding.");
+			ssh_packet_send_debug(ssh, "Server has disabled port forwarding.");
 		} else {
 			/* Start listening on the port */
-			success = channel_setup_remote_fwd_listener(&fwd,
+			success = channel_setup_remote_fwd_listener(ssh, &fwd,
 			    &allocated_listen_port, &options.fwd_opts);
 		}
-		free(fwd.listen_host);
 		if ((resp = sshbuf_new()) == NULL)
 			fatal("%s: sshbuf_new", __func__);
-		if ((r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
+		if (allocated_listen_port != 0 &&
+		    (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
 			fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
 	} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
-		struct Forward fwd;
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
+		    (r = sshpkt_get_u32(ssh, &port)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse cancel-tcpip-forward", __func__);
 
-		memset(&fwd, 0, sizeof(fwd));
-		fwd.listen_host = packet_get_string(NULL);
-		fwd.listen_port = (u_short)packet_get_int();
 		debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
-		    fwd.listen_host, fwd.listen_port);
-
-		success = channel_cancel_rport_listener(&fwd);
-		free(fwd.listen_host);
+		    fwd.listen_host, port);
+		if (port <= INT_MAX) {
+			fwd.listen_port = (int)port;
+			success = channel_cancel_rport_listener(ssh, &fwd);
+		}
 	} else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
-		struct Forward fwd;
-
-		memset(&fwd, 0, sizeof(fwd));
-		fwd.listen_path = packet_get_string(NULL);
-		debug("server_input_global_request: streamlocal-forward listen path %s",
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse streamlocal-forward@openssh.com", __func__);
+		debug("%s: streamlocal-forward listen path %s", __func__,
 		    fwd.listen_path);
 
 		/* check permissions */
 		if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
-		    || no_port_forwarding_flag) {
+		    || !auth_opts->permit_port_forwarding_flag ||
+		    options.disable_forwarding ||
+		    (pw->pw_uid != 0 && !use_privsep)) {
 			success = 0;
-			packet_send_debug("Server has disabled port forwarding.");
+			ssh_packet_send_debug(ssh, "Server has disabled "
+			    "streamlocal forwarding.");
 		} else {
 			/* Start listening on the socket */
-			success = channel_setup_remote_fwd_listener(
+			success = channel_setup_remote_fwd_listener(ssh,
 			    &fwd, NULL, &options.fwd_opts);
 		}
-		free(fwd.listen_path);
 	} else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
-		struct Forward fwd;
-
-		memset(&fwd, 0, sizeof(fwd));
-		fwd.listen_path = packet_get_string(NULL);
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse cancel-streamlocal-forward@openssh.com", __func__);
 		debug("%s: cancel-streamlocal-forward path %s", __func__,
 		    fwd.listen_path);
 
-		success = channel_cancel_rport_listener(&fwd);
-		free(fwd.listen_path);
+		success = channel_cancel_rport_listener(ssh, &fwd);
 	} else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
 		no_more_sessions = 1;
 		success = 1;
 	} else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
-		success = server_input_hostkeys_prove(&resp);
+		success = server_input_hostkeys_prove(ssh, &resp);
 	}
+	/* XXX sshpkt_get_end() */
 	if (want_reply) {
-		packet_start(success ?
-		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
-		if (success && resp != NULL)
-			ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
-			    sshbuf_len(resp));
-		packet_send();
-		packet_write_wait();
-	}
+		if ((r = sshpkt_start(ssh, success ?
+		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE)) != 0 ||
+		    (success && resp != NULL && (r = sshpkt_putb(ssh, resp)) != 0) ||
+		    (r = sshpkt_send(ssh)) != 0 ||
+		    (r = ssh_packet_write_wait(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: send reply", __func__);
+	}
+	free(fwd.listen_host);
+	free(fwd.listen_path);
 	free(rtype);
 	sshbuf_free(resp);
 	return 0;
 }
 
 static int
-server_input_channel_req(int type, u_int32_t seq, void *ctxt)
+server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
 {
 	Channel *c;
-	int id, reply, success = 0;
-	char *rtype;
+	int r, success = 0;
+	char *rtype = NULL;
+	u_char want_reply = 0;
+	u_int id = 0;
 
-	id = packet_get_int();
-	rtype = packet_get_string(NULL);
-	reply = packet_get_char();
+	if ((r = sshpkt_get_u32(ssh, &id)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
+	    (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
 
-	debug("server_input_channel_req: channel %d request %s reply %d",
-	    id, rtype, reply);
+	debug("server_input_channel_req: channel %u request %s reply %d",
+	    id, rtype, want_reply);
 
-	if ((c = channel_lookup(id)) == NULL)
-		packet_disconnect("server_input_channel_req: "
-		    "unknown channel %d", id);
+	if (id >= INT_MAX || (c = channel_lookup(ssh, (int)id)) == NULL) {
+		ssh_packet_disconnect(ssh, "%s: unknown channel %d",
+		    __func__, id);
+	}
 	if (!strcmp(rtype, "eow@openssh.com")) {
-		packet_check_eom();
-		chan_rcvd_eow(c);
+		if ((r = sshpkt_get_end(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+		chan_rcvd_eow(ssh, c);
 	} else if ((c->type == SSH_CHANNEL_LARVAL ||
 	    c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
-		success = session_input_channel_req(c, rtype);
-	if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
-		packet_start(success ?
-		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
-		packet_put_int(c->remote_id);
-		packet_send();
+		success = session_input_channel_req(ssh, c, rtype);
+	if (want_reply && !(c->flags & CHAN_CLOSE_SENT)) {
+		if (!c->have_remote_id)
+			fatal("%s: channel %d: no remote_id",
+			    __func__, c->self);
+		if ((r = sshpkt_start(ssh, success ?
+		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: send reply", __func__);
 	}
 	free(rtype);
 	return 0;
 }
 
 static 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, &server_input_channel_req);
-	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
-	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
+server_init_dispatch(struct ssh *ssh)
+{
+	debug("server_init_dispatch");
+	ssh_dispatch_init(ssh, &dispatch_protocol_error);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
+	ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
 	/* client_alive */
-	dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
-	dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
-	dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
-	dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
+	ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
+	ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
 	/* rekeying */
-	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
-}
-static 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);
-}
-static 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);
-}
-static void
-server_init_dispatch(void)
-{
-	if (compat20)
-		server_init_dispatch_20();
-	else if (compat13)
-		server_init_dispatch_13();
-	else
-		server_init_dispatch_15();
+	ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
 }