Merge upstream-master into master

Commit ecb2c02d994b3e21994f31a70ff911667c262f1f upstream

This nearly (but not quite) corresponds to V_8_3_P1; subsequent
cherry-picks will correct this.

Bug: 162492243
Change-Id: I3c079d86435b7c25aefff4538dc89a3002b1e25b

1 files changed, 785 insertions, 941 deletions

diff --git a/packet.c b/packet.c
index b1219c85..e7abb341 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.208 2015/02/13 18:57:00 markus Exp $ */
+/* $OpenBSD: packet.c,v 1.291 2020/03/06 18:20:44 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -38,8 +38,7 @@
  */
 
 #include "includes.h"
- 
-#include <sys/param.h>	/* MIN roundup */
+
 #include <sys/types.h>
 #include "openbsd-compat/sys-queue.h"
 #include <sys/socket.h>
@@ -52,25 +51,37 @@
 #include <arpa/inet.h>
 
 #include <errno.h>
+#include <netdb.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <limits.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
 #include <signal.h>
 #include <time.h>
 
-#include <zlib.h>
+/*
+ * Explicitly include OpenSSL before zlib as some versions of OpenSSL have
+ * "free_func" in their headers, which zlib typedefs.
+ */
+#ifdef WITH_OPENSSL
+# include <openssl/bn.h>
+# include <openssl/evp.h>
+# ifdef OPENSSL_HAS_ECC
+#  include <openssl/ec.h>
+# endif
+#endif
 
-#include "buffer.h"	/* typedefs XXX */
-#include "key.h"	/* typedefs XXX */
+#ifdef WITH_ZLIB
+#include <zlib.h>
+#endif
 
 #include "xmalloc.h"
-#include "crc32.h"
-#include "deattack.h"
 #include "compat.h"
-#include "ssh1.h"
 #include "ssh2.h"
 #include "cipher.h"
 #include "sshkey.h"
@@ -83,7 +94,6 @@
 #include "channels.h"
 #include "ssh.h"
 #include "packet.h"
-#include "roaming.h"
 #include "ssherr.h"
 #include "sshbuf.h"
 
@@ -122,10 +132,10 @@ struct session_state {
 	u_int remote_protocol_flags;
 
 	/* Encryption context for receiving data.  Only used for decryption. */
-	struct sshcipher_ctx receive_context;
+	struct sshcipher_ctx *receive_context;
 
 	/* Encryption context for sending data.  Only used for encryption. */
-	struct sshcipher_ctx send_context;
+	struct sshcipher_ctx *send_context;
 
 	/* Buffer for raw input data from the socket. */
 	struct sshbuf *input;
@@ -142,20 +152,16 @@ struct session_state {
 	/* Scratch buffer for packet compression/decompression. */
 	struct sshbuf *compression_buffer;
 
+#ifdef WITH_ZLIB
 	/* Incoming/outgoing compression dictionaries */
 	z_stream compression_in_stream;
 	z_stream compression_out_stream;
+#endif
 	int compression_in_started;
 	int compression_out_started;
 	int compression_in_failures;
 	int compression_out_failures;
 
-	/*
-	 * Flag indicating whether packet compression/decompression is
-	 * enabled.
-	 */
-	int packet_compression;
-
 	/* default maximum packet size */
 	u_int max_packet_size;
 
@@ -181,22 +187,18 @@ struct session_state {
 	struct packet_state p_read, p_send;
 
 	/* Volume-based rekeying */
-	u_int64_t max_blocks_in, max_blocks_out;
-	u_int32_t rekey_limit;
+	u_int64_t max_blocks_in, max_blocks_out, rekey_limit;
 
 	/* Time-based rekeying */
 	u_int32_t rekey_interval;	/* how often in seconds */
 	time_t rekey_time;	/* time of last rekeying */
 
-	/* Session key for protocol v1 */
-	u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
-	u_int ssh1_keylen;
-
 	/* roundup current message to extra_pad bytes */
 	u_char extra_pad;
 
 	/* XXX discard incoming data after MAC error */
 	u_int packet_discard;
+	size_t packet_discard_mac_already;
 	struct sshmac *packet_discard_mac;
 
 	/* Used in packet_read_poll2() */
@@ -205,6 +207,9 @@ struct session_state {
 	/* Used in packet_send2 */
 	int rekeying;
 
+	/* Used in ssh_packet_send_mux() */
+	int mux;
+
 	/* Used in packet_set_interactive */
 	int set_interactive_called;
 
@@ -214,8 +219,9 @@ struct session_state {
 	/* One-off warning about weak ciphers */
 	int cipher_warning_done;
 
-	/* SSH1 CRC compensation attack detector */
-	struct deattack_ctx deattack;
+	/* Hook for fuzzing inbound packets */
+	ssh_packet_hook_fn *hook_in;
+	void *hook_in_ctx;
 
 	TAILQ_HEAD(, packet) outgoing;
 };
@@ -228,6 +234,7 @@ ssh_alloc_session_state(void)
 
 	if ((ssh = calloc(1, sizeof(*ssh))) == NULL ||
 	    (state = calloc(1, sizeof(*state))) == NULL ||
+	    (ssh->kex = kex_new()) == NULL ||
 	    (state->input = sshbuf_new()) == NULL ||
 	    (state->output = sshbuf_new()) == NULL ||
 	    (state->outgoing_packet = sshbuf_new()) == NULL ||
@@ -250,6 +257,10 @@ ssh_alloc_session_state(void)
 	ssh->state = state;
 	return ssh;
  fail:
+	if (ssh) {
+		kex_free(ssh->kex);
+		free(ssh);
+	}
 	if (state) {
 		sshbuf_free(state->input);
 		sshbuf_free(state->output);
@@ -257,13 +268,25 @@ ssh_alloc_session_state(void)
 		sshbuf_free(state->outgoing_packet);
 		free(state);
 	}
-	free(ssh);
 	return NULL;
 }
 
+void
+ssh_packet_set_input_hook(struct ssh *ssh, ssh_packet_hook_fn *hook, void *ctx)
+{
+	ssh->state->hook_in = hook;
+	ssh->state->hook_in_ctx = ctx;
+}
+
+/* Returns nonzero if rekeying is in progress */
+int
+ssh_packet_is_rekeying(struct ssh *ssh)
+{
+	return ssh->state->rekeying || ssh->kex->done == 0;
+}
+
 /*
- * Sets the descriptors used for communication.  Disables encryption until
- * packet_set_encryption_key is called.
+ * Sets the descriptors used for communication.
  */
 struct ssh *
 ssh_packet_set_connection(struct ssh *ssh, int fd_in, int fd_out)
@@ -279,7 +302,7 @@ ssh_packet_set_connection(struct ssh *ssh, int fd_in, int fd_out)
 	if (ssh == NULL)
 		ssh = ssh_alloc_session_state();
 	if (ssh == NULL) {
-		error("%s: cound not allocate state", __func__);
+		error("%s: could not allocate state", __func__);
 		return NULL;
 	}
 	state = ssh->state;
@@ -290,10 +313,10 @@ ssh_packet_set_connection(struct ssh *ssh, int fd_in, int fd_out)
 	    (r = cipher_init(&state->receive_context, none,
 	    (const u_char *)"", 0, NULL, 0, CIPHER_DECRYPT)) != 0) {
 		error("%s: cipher_init failed: %s", __func__, ssh_err(r));
+		free(ssh); /* XXX need ssh_free_session_state? */
 		return NULL;
 	}
 	state->newkeys[MODE_IN] = state->newkeys[MODE_OUT] = NULL;
-	deattack_init(&state->deattack);
 	/*
 	 * Cache the IP address of the remote connection for use in error
 	 * messages that might be generated after the connection has closed.
@@ -317,6 +340,38 @@ ssh_packet_set_timeout(struct ssh *ssh, int timeout, int count)
 		state->packet_timeout_ms = timeout * count * 1000;
 }
 
+void
+ssh_packet_set_mux(struct ssh *ssh)
+{
+	ssh->state->mux = 1;
+	ssh->state->rekeying = 0;
+}
+
+int
+ssh_packet_get_mux(struct ssh *ssh)
+{
+	return ssh->state->mux;
+}
+
+int
+ssh_packet_set_log_preamble(struct ssh *ssh, const char *fmt, ...)
+{
+	va_list args;
+	int r;
+
+	free(ssh->log_preamble);
+	if (fmt == NULL)
+		ssh->log_preamble = NULL;
+	else {
+		va_start(args, fmt);
+		r = vasprintf(&ssh->log_preamble, fmt, args);
+		va_end(args);
+		if (r < 0 || ssh->log_preamble == NULL)
+			return SSH_ERR_ALLOC_FAIL;
+	}
+	return 0;
+}
+
 int
 ssh_packet_stop_discard(struct ssh *ssh)
 {
@@ -325,25 +380,28 @@ ssh_packet_stop_discard(struct ssh *ssh)
 
 	if (state->packet_discard_mac) {
 		char buf[1024];
+		size_t dlen = PACKET_MAX_SIZE;
 
+		if (dlen > state->packet_discard_mac_already)
+			dlen -= state->packet_discard_mac_already;
 		memset(buf, 'a', sizeof(buf));
-		while (sshbuf_len(state->incoming_packet) <
-		    PACKET_MAX_SIZE)
+		while (sshbuf_len(state->incoming_packet) < dlen)
 			if ((r = sshbuf_put(state->incoming_packet, buf,
 			    sizeof(buf))) != 0)
 				return r;
 		(void) mac_compute(state->packet_discard_mac,
 		    state->p_read.seqnr,
-		    sshbuf_ptr(state->incoming_packet), PACKET_MAX_SIZE,
+		    sshbuf_ptr(state->incoming_packet), dlen,
 		    NULL, 0);
 	}
-	logit("Finished discarding for %.200s", ssh_remote_ipaddr(ssh));
+	logit("Finished discarding for %.200s port %d",
+	    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
 	return SSH_ERR_MAC_INVALID;
 }
 
 static int
 ssh_packet_start_discard(struct ssh *ssh, struct sshenc *enc,
-    struct sshmac *mac, u_int packet_length, u_int discard)
+    struct sshmac *mac, size_t mac_already, u_int discard)
 {
 	struct session_state *state = ssh->state;
 	int r;
@@ -353,11 +411,16 @@ ssh_packet_start_discard(struct ssh *ssh, struct sshenc *enc,
 			return r;
 		return SSH_ERR_MAC_INVALID;
 	}
-	if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
+	/*
+	 * Record number of bytes over which the mac has already
+	 * been computed in order to minimize timing attacks.
+	 */
+	if (mac && mac->enabled) {
 		state->packet_discard_mac = mac;
-	if (sshbuf_len(state->input) >= discard &&
-	   (r = ssh_packet_stop_discard(ssh)) != 0)
-		return r;
+		state->packet_discard_mac_already = mac_already;
+	}
+	if (sshbuf_len(state->input) >= discard)
+		return ssh_packet_stop_discard(ssh);
 	state->packet_discard = discard - sshbuf_len(state->input);
 	return 0;
 }
@@ -367,22 +430,28 @@ ssh_packet_start_discard(struct ssh *ssh, struct sshenc *enc,
 int
 ssh_packet_connection_is_on_socket(struct ssh *ssh)
 {
-	struct session_state *state = ssh->state;
+	struct session_state *state;
 	struct sockaddr_storage from, to;
 	socklen_t fromlen, tolen;
 
+	if (ssh == NULL || ssh->state == NULL)
+		return 0;
+
+	state = ssh->state;
+	if (state->connection_in == -1 || state->connection_out == -1)
+		return 0;
 	/* filedescriptors in and out are the same, so it's a socket */
 	if (state->connection_in == state->connection_out)
 		return 1;
 	fromlen = sizeof(from);
 	memset(&from, 0, sizeof(from));
 	if (getpeername(state->connection_in, (struct sockaddr *)&from,
-	    &fromlen) < 0)
+	    &fromlen) == -1)
 		return 0;
 	tolen = sizeof(to);
 	memset(&to, 0, sizeof(to));
 	if (getpeername(state->connection_out, (struct sockaddr *)&to,
-	    &tolen) < 0)
+	    &tolen) == -1)
 		return 0;
 	if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 		return 0;
@@ -408,7 +477,7 @@ ssh_packet_connection_af(struct ssh *ssh)
 
 	memset(&to, 0, sizeof(to));
 	if (getsockname(ssh->state->connection_out, (struct sockaddr *)&to,
-	    &tolen) < 0)
+	    &tolen) == -1)
 		return 0;
 #ifdef IPV4_IN_IPV6
 	if (to.ss_family == AF_INET6 &&
@@ -454,42 +523,99 @@ ssh_packet_get_connection_out(struct ssh *ssh)
 const char *
 ssh_remote_ipaddr(struct ssh *ssh)
 {
+	int sock;
+
 	/* Check whether we have cached the ipaddr. */
-	if (ssh->remote_ipaddr == NULL)
-		ssh->remote_ipaddr = ssh_packet_connection_is_on_socket(ssh) ?
-		    get_peer_ipaddr(ssh->state->connection_in) :
-		    strdup("UNKNOWN");
-	if (ssh->remote_ipaddr == NULL)
-		return "UNKNOWN";
+	if (ssh->remote_ipaddr == NULL) {
+		if (ssh_packet_connection_is_on_socket(ssh)) {
+			sock = ssh->state->connection_in;
+			ssh->remote_ipaddr = get_peer_ipaddr(sock);
+			ssh->remote_port = get_peer_port(sock);
+			ssh->local_ipaddr = get_local_ipaddr(sock);
+			ssh->local_port = get_local_port(sock);
+		} else {
+			ssh->remote_ipaddr = xstrdup("UNKNOWN");
+			ssh->remote_port = 65535;
+			ssh->local_ipaddr = xstrdup("UNKNOWN");
+			ssh->local_port = 65535;
+		}
+	}
 	return ssh->remote_ipaddr;
 }
 
+/* Returns the port number of the remote host. */
+
+int
+ssh_remote_port(struct ssh *ssh)
+{
+	(void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */
+	return ssh->remote_port;
+}
+
+/*
+ * Returns the IP-address of the local host as a string.  The returned
+ * string must not be freed.
+ */
+
+const char *
+ssh_local_ipaddr(struct ssh *ssh)
+{
+	(void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */
+	return ssh->local_ipaddr;
+}
+
+/* Returns the port number of the local host. */
+
+int
+ssh_local_port(struct ssh *ssh)
+{
+	(void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */
+	return ssh->local_port;
+}
+
+/* Returns the routing domain of the input socket, or NULL if unavailable */
+const char *
+ssh_packet_rdomain_in(struct ssh *ssh)
+{
+	if (ssh->rdomain_in != NULL)
+		return ssh->rdomain_in;
+	if (!ssh_packet_connection_is_on_socket(ssh))
+		return NULL;
+	ssh->rdomain_in = get_rdomain(ssh->state->connection_in);
+	return ssh->rdomain_in;
+}
+
 /* Closes the connection and clears and frees internal data structures. */
 
-void
-ssh_packet_close(struct ssh *ssh)
+static void
+ssh_packet_close_internal(struct ssh *ssh, int do_close)
 {
 	struct session_state *state = ssh->state;
-	int r;
 	u_int mode;
 
 	if (!state->initialized)
 		return;
 	state->initialized = 0;
-	if (state->connection_in == state->connection_out) {
-		shutdown(state->connection_out, SHUT_RDWR);
-		close(state->connection_out);
-	} else {
-		close(state->connection_in);
-		close(state->connection_out);
+	if (do_close) {
+		if (state->connection_in == state->connection_out) {
+			close(state->connection_out);
+		} else {
+			close(state->connection_in);
+			close(state->connection_out);
+		}
 	}
 	sshbuf_free(state->input);
 	sshbuf_free(state->output);
 	sshbuf_free(state->outgoing_packet);
 	sshbuf_free(state->incoming_packet);
-	for (mode = 0; mode < MODE_MAX; mode++)
-		kex_free_newkeys(state->newkeys[mode]);
-	if (state->compression_buffer) {
+	for (mode = 0; mode < MODE_MAX; mode++) {
+		kex_free_newkeys(state->newkeys[mode]);	/* current keys */
+		state->newkeys[mode] = NULL;
+		ssh_clear_newkeys(ssh, mode);		/* next keys */
+	}
+#ifdef WITH_ZLIB
+	/* compression state is in shared mem, so we can only release it once */
+	if (do_close && state->compression_buffer) {
 		sshbuf_free(state->compression_buffer);
 		if (state->compression_out_started) {
 			z_streamp stream = &state->compression_out_stream;
@@ -503,7 +629,7 @@ ssh_packet_close(struct ssh *ssh)
 				deflateEnd(stream);
 		}
 		if (state->compression_in_started) {
-			z_streamp stream = &state->compression_out_stream;
+			z_streamp stream = &state->compression_in_stream;
 			debug("compress incoming: "
 			    "raw data %llu, compressed %llu, factor %.2f",
 			    (unsigned long long)stream->total_out,
@@ -514,16 +640,30 @@ ssh_packet_close(struct ssh *ssh)
 				inflateEnd(stream);
 		}
 	}
-	if ((r = cipher_cleanup(&state->send_context)) != 0)
-		error("%s: cipher_cleanup failed: %s", __func__, ssh_err(r));
-	if ((r = cipher_cleanup(&state->receive_context)) != 0)
-		error("%s: cipher_cleanup failed: %s", __func__, ssh_err(r));
-	if (ssh->remote_ipaddr) {
+#endif	/* WITH_ZLIB */
+	cipher_free(state->send_context);
+	cipher_free(state->receive_context);
+	state->send_context = state->receive_context = NULL;
+	if (do_close) {
+		free(ssh->local_ipaddr);
+		ssh->local_ipaddr = NULL;
 		free(ssh->remote_ipaddr);
 		ssh->remote_ipaddr = NULL;
+		free(ssh->state);
+		ssh->state = NULL;
 	}
-	free(ssh->state);
-	ssh->state = NULL;
+}
+
+void
+ssh_packet_close(struct ssh *ssh)
+{
+	ssh_packet_close_internal(ssh, 1);
+}
+
+void
+ssh_packet_clear_keys(struct ssh *ssh)
+{
+	ssh_packet_close_internal(ssh, 0);
 }
 
 /* Sets remote side protocol flags. */
@@ -556,6 +696,7 @@ ssh_packet_init_compression(struct ssh *ssh)
 	return 0;
 }
 
+#ifdef WITH_ZLIB
 static int
 start_compression_out(struct ssh *ssh, int level)
 {
@@ -593,21 +734,6 @@ start_compression_in(struct ssh *ssh)
 	return 0;
 }
 
-int
-ssh_packet_start_compression(struct ssh *ssh, int level)
-{
-	int r;
-
-	if (ssh->state->packet_compression && !compat20)
-		return SSH_ERR_INTERNAL_ERROR;
-	ssh->state->packet_compression = 1;
-	if ((r = ssh_packet_init_compression(ssh)) != 0 ||
-	    (r = start_compression_in(ssh)) != 0 ||
-	    (r = start_compression_out(ssh, level)) != 0)
-		return r;
-	return 0;
-}
-
 /* XXX remove need for separate compression buffer */
 static int
 compress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
@@ -702,214 +828,40 @@ uncompress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
 	/* NOTREACHED */
 }
 
-/* Serialise compression state into a blob for privsep */
+#else	/* WITH_ZLIB */
+
 static int
-ssh_packet_get_compress_state(struct sshbuf *m, struct ssh *ssh)
+start_compression_out(struct ssh *ssh, int level)
 {
-	struct session_state *state = ssh->state;
-	struct sshbuf *b;
-	int r;
-
-	if ((b = sshbuf_new()) == NULL)
-		return SSH_ERR_ALLOC_FAIL;
-	if (state->compression_in_started) {
-		if ((r = sshbuf_put_string(b, &state->compression_in_stream,
-		    sizeof(state->compression_in_stream))) != 0)
-			goto out;
-	} else if ((r = sshbuf_put_string(b, NULL, 0)) != 0)
-		goto out;
-	if (state->compression_out_started) {
-		if ((r = sshbuf_put_string(b, &state->compression_out_stream,
-		    sizeof(state->compression_out_stream))) != 0)
-			goto out;
-	} else if ((r = sshbuf_put_string(b, NULL, 0)) != 0)
-		goto out;
-	r = sshbuf_put_stringb(m, b);
- out:
-	sshbuf_free(b);
-	return r;
+	return SSH_ERR_INTERNAL_ERROR;
 }
 
-/* Deserialise compression state from a blob for privsep */
 static int
-ssh_packet_set_compress_state(struct ssh *ssh, struct sshbuf *m)
+start_compression_in(struct ssh *ssh)
 {
-	struct session_state *state = ssh->state;
-	struct sshbuf *b = NULL;
-	int r;
-	const u_char *inblob, *outblob;
-	size_t inl, outl;
-
-	if ((r = sshbuf_froms(m, &b)) != 0)
-		goto out;
-	if ((r = sshbuf_get_string_direct(b, &inblob, &inl)) != 0 ||
-	    (r = sshbuf_get_string_direct(b, &outblob, &outl)) != 0)
-		goto out;
-	if (inl == 0)
-		state->compression_in_started = 0;
-	else if (inl != sizeof(state->compression_in_stream)) {
-		r = SSH_ERR_INTERNAL_ERROR;
-		goto out;
-	} else {
-		state->compression_in_started = 1;
-		memcpy(&state->compression_in_stream, inblob, inl);
-	}
-	if (outl == 0)
-		state->compression_out_started = 0;
-	else if (outl != sizeof(state->compression_out_stream)) {
-		r = SSH_ERR_INTERNAL_ERROR;
-		goto out;
-	} else {
-		state->compression_out_started = 1;
-		memcpy(&state->compression_out_stream, outblob, outl);
-	}
-	r = 0;
- out:
-	sshbuf_free(b);
-	return r;
+	return SSH_ERR_INTERNAL_ERROR;
 }
 
-void
-ssh_packet_set_compress_hooks(struct ssh *ssh, void *ctx,
-    void *(*allocfunc)(void *, u_int, u_int),
-    void (*freefunc)(void *, void *))
+static int
+compress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
 {
-	ssh->state->compression_out_stream.zalloc = (alloc_func)allocfunc;
-	ssh->state->compression_out_stream.zfree = (free_func)freefunc;
-	ssh->state->compression_out_stream.opaque = ctx;
-	ssh->state->compression_in_stream.zalloc = (alloc_func)allocfunc;
-	ssh->state->compression_in_stream.zfree = (free_func)freefunc;
-	ssh->state->compression_in_stream.opaque = ctx;
+	return SSH_ERR_INTERNAL_ERROR;
 }
 
-/*
- * Causes any further packets to be encrypted using the given key.  The same
- * key is used for both sending and reception.  However, both directions are
- * encrypted independently of each other.
- */
-
-void
-ssh_packet_set_encryption_key(struct ssh *ssh, const u_char *key, u_int keylen, int number)
+static int
+uncompress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
 {
-#ifdef WITH_SSH1
-	struct session_state *state = ssh->state;
-	const struct sshcipher *cipher = cipher_by_number(number);
-	int r;
-	const char *wmsg;
-
-	if (cipher == NULL)
-		fatal("%s: unknown cipher number %d", __func__, number);
-	if (keylen < 20)
-		fatal("%s: keylen too small: %d", __func__, keylen);
-	if (keylen > SSH_SESSION_KEY_LENGTH)
-		fatal("%s: keylen too big: %d", __func__, keylen);
-	memcpy(state->ssh1_key, key, keylen);
-	state->ssh1_keylen = keylen;
-	if ((r = cipher_init(&state->send_context, cipher, key, keylen,
-	    NULL, 0, CIPHER_ENCRYPT)) != 0 ||
-	    (r = cipher_init(&state->receive_context, cipher, key, keylen,
-	    NULL, 0, CIPHER_DECRYPT) != 0))
-		fatal("%s: cipher_init failed: %s", __func__, ssh_err(r));
-	if (!state->cipher_warning_done &&
-	    ((wmsg = cipher_warning_message(&state->send_context)) != NULL ||
-	    (wmsg = cipher_warning_message(&state->send_context)) != NULL)) {
-		error("Warning: %s", wmsg);
-		state->cipher_warning_done = 1;
-	}
-#endif /* WITH_SSH1 */
+	return SSH_ERR_INTERNAL_ERROR;
 }
+#endif	/* WITH_ZLIB */
 
-/*
- * Finalizes and sends the packet.  If the encryption key has been set,
- * encrypts the packet before sending.
- */
-
-int
-ssh_packet_send1(struct ssh *ssh)
+void
+ssh_clear_newkeys(struct ssh *ssh, int mode)
 {
-	struct session_state *state = ssh->state;
-	u_char buf[8], *cp;
-	int r, padding, len;
-	u_int checksum;
-
-	/*
-	 * If using packet compression, compress the payload of the outgoing
-	 * packet.
-	 */
-	if (state->packet_compression) {
-		sshbuf_reset(state->compression_buffer);
-		/* Skip padding. */
-		if ((r = sshbuf_consume(state->outgoing_packet, 8)) != 0)
-			goto out;
-		/* padding */
-		if ((r = sshbuf_put(state->compression_buffer,
-		    "\0\0\0\0\0\0\0\0", 8)) != 0)
-			goto out;
-		if ((r = compress_buffer(ssh, state->outgoing_packet,
-		    state->compression_buffer)) != 0)
-			goto out;
-		sshbuf_reset(state->outgoing_packet);
-                if ((r = sshbuf_putb(state->outgoing_packet,
-                    state->compression_buffer)) != 0)
-			goto out;
+	if (ssh->kex && ssh->kex->newkeys[mode]) {
+		kex_free_newkeys(ssh->kex->newkeys[mode]);
+		ssh->kex->newkeys[mode] = NULL;
 	}
-	/* Compute packet length without padding (add checksum, remove padding). */
-	len = sshbuf_len(state->outgoing_packet) + 4 - 8;
-
-	/* Insert padding. Initialized to zero in packet_start1() */
-	padding = 8 - len % 8;
-	if (!state->send_context.plaintext) {
-		cp = sshbuf_mutable_ptr(state->outgoing_packet);
-		if (cp == NULL) {
-			r = SSH_ERR_INTERNAL_ERROR;
-			goto out;
-		}
-		arc4random_buf(cp + 8 - padding, padding);
-	}
-	if ((r = sshbuf_consume(state->outgoing_packet, 8 - padding)) != 0)
-		goto out;
-
-	/* Add check bytes. */
-	checksum = ssh_crc32(sshbuf_ptr(state->outgoing_packet),
-	    sshbuf_len(state->outgoing_packet));
-	POKE_U32(buf, checksum);
-	if ((r = sshbuf_put(state->outgoing_packet, buf, 4)) != 0)
-		goto out;
-
-#ifdef PACKET_DEBUG
-	fprintf(stderr, "packet_send plain: ");
-	sshbuf_dump(state->outgoing_packet, stderr);
-#endif
-
-	/* Append to output. */
-	POKE_U32(buf, len);
-	if ((r = sshbuf_put(state->output, buf, 4)) != 0)
-		goto out;
-	if ((r = sshbuf_reserve(state->output,
-	    sshbuf_len(state->outgoing_packet), &cp)) != 0)
-		goto out;
-	if ((r = cipher_crypt(&state->send_context, 0, cp,
-	    sshbuf_ptr(state->outgoing_packet),
-	    sshbuf_len(state->outgoing_packet), 0, 0)) != 0)
-		goto out;
-
-#ifdef PACKET_DEBUG
-	fprintf(stderr, "encrypted: ");
-	sshbuf_dump(state->output, stderr);
-#endif
-	state->p_send.packets++;
-	state->p_send.bytes += len +
-	    sshbuf_len(state->outgoing_packet);
-	sshbuf_reset(state->outgoing_packet);
-
-	/*
-	 * Note that the packet is now only buffered in output.  It won't be
-	 * actually sent until ssh_packet_write_wait or ssh_packet_write_poll
-	 * is called.
-	 */
-	r = 0;
- out:
-	return r;
 }
 
 int
@@ -919,43 +871,38 @@ ssh_set_newkeys(struct ssh *ssh, int mode)
 	struct sshenc *enc;
 	struct sshmac *mac;
 	struct sshcomp *comp;
-	struct sshcipher_ctx *cc;
+	struct sshcipher_ctx **ccp;
+	struct packet_state *ps;
 	u_int64_t *max_blocks;
 	const char *wmsg;
 	int r, crypt_type;
+	const char *dir = mode == MODE_OUT ? "out" : "in";
 
 	debug2("set_newkeys: mode %d", mode);
 
 	if (mode == MODE_OUT) {
-		cc = &state->send_context;
+		ccp = &state->send_context;
 		crypt_type = CIPHER_ENCRYPT;
-		state->p_send.packets = state->p_send.blocks = 0;
+		ps = &state->p_send;
 		max_blocks = &state->max_blocks_out;
 	} else {
-		cc = &state->receive_context;
+		ccp = &state->receive_context;
 		crypt_type = CIPHER_DECRYPT;
-		state->p_read.packets = state->p_read.blocks = 0;
+		ps = &state->p_read;
 		max_blocks = &state->max_blocks_in;
 	}
 	if (state->newkeys[mode] != NULL) {
-		debug("set_newkeys: rekeying");
-		if ((r = cipher_cleanup(cc)) != 0)
-			return r;
-		enc  = &state->newkeys[mode]->enc;
-		mac  = &state->newkeys[mode]->mac;
-		comp = &state->newkeys[mode]->comp;
-		mac_clear(mac);
-		explicit_bzero(enc->iv,  enc->iv_len);
-		explicit_bzero(enc->key, enc->key_len);
-		explicit_bzero(mac->key, mac->key_len);
-		free(enc->name);
-		free(enc->iv);
-		free(enc->key);
-		free(mac->name);
-		free(mac->key);
-		free(comp->name);
-		free(state->newkeys[mode]);
+		debug("%s: rekeying %s, input %llu bytes %llu blocks, "
+		   "output %llu bytes %llu blocks", __func__, dir,
+		   (unsigned long long)state->p_read.bytes,
+		   (unsigned long long)state->p_read.blocks,
+		   (unsigned long long)state->p_send.bytes,
+		   (unsigned long long)state->p_send.blocks);
+		kex_free_newkeys(state->newkeys[mode]);
+		state->newkeys[mode] = NULL;
 	}
+	/* note that both bytes and the seqnr are not reset */
+	ps->packets = ps->blocks = 0;
 	/* move newkeys from kex to state */
 	if ((state->newkeys[mode] = ssh->kex->newkeys[mode]) == NULL)
 		return SSH_ERR_INTERNAL_ERROR;
@@ -968,12 +915,14 @@ ssh_set_newkeys(struct ssh *ssh, int mode)
 			return r;
 	}
 	mac->enabled = 1;
-	DBG(debug("cipher_init_context: %d", mode));
-	if ((r = cipher_init(cc, enc->cipher, enc->key, enc->key_len,
+	DBG(debug("%s: cipher_init_context: %s", __func__, dir));
+	cipher_free(*ccp);
+	*ccp = NULL;
+	if ((r = cipher_init(ccp, enc->cipher, enc->key, enc->key_len,
 	    enc->iv, enc->iv_len, crypt_type)) != 0)
 		return r;
 	if (!state->cipher_warning_done &&
-	    (wmsg = cipher_warning_message(cc)) != NULL) {
+	    (wmsg = cipher_warning_message(*ccp)) != NULL) {
 		error("Warning: %s", wmsg);
 		state->cipher_warning_done = 1;
 	}
@@ -997,18 +946,69 @@ ssh_set_newkeys(struct ssh *ssh, int mode)
 	}
 	/*
 	 * The 2^(blocksize*2) limit is too expensive for 3DES,
-	 * blowfish, etc, so enforce a 1GB limit for small blocksizes.
+	 * so enforce a 1GB limit for small blocksizes.
+	 * See RFC4344 section 3.2.
 	 */
 	if (enc->block_size >= 16)
 		*max_blocks = (u_int64_t)1 << (enc->block_size*2);
 	else
 		*max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 	if (state->rekey_limit)
-		*max_blocks = MIN(*max_blocks,
+		*max_blocks = MINIMUM(*max_blocks,
 		    state->rekey_limit / enc->block_size);
+	debug("rekey %s after %llu blocks", dir,
+	    (unsigned long long)*max_blocks);
 	return 0;
 }
 
+#define MAX_PACKETS	(1U<<31)
+static int
+ssh_packet_need_rekeying(struct ssh *ssh, u_int outbound_packet_len)
+{
+	struct session_state *state = ssh->state;
+	u_int32_t out_blocks;
+
+	/* XXX client can't cope with rekeying pre-auth */
+	if (!state->after_authentication)
+		return 0;
+
+	/* Haven't keyed yet or KEX in progress. */
+	if (ssh_packet_is_rekeying(ssh))
+		return 0;
+
+	/* Peer can't rekey */
+	if (ssh->compat & SSH_BUG_NOREKEY)
+		return 0;
+
+	/*
+	 * Permit one packet in or out per rekey - this allows us to
+	 * make progress when rekey limits are very small.
+	 */
+	if (state->p_send.packets == 0 && state->p_read.packets == 0)
+		return 0;
+
+	/* Time-based rekeying */
+	if (state->rekey_interval != 0 &&
+	    (int64_t)state->rekey_time + state->rekey_interval <= monotime())
+		return 1;
+
+	/*
+	 * Always rekey when MAX_PACKETS sent in either direction 
+	 * As per RFC4344 section 3.1 we do this after 2^31 packets.
+	 */
+	if (state->p_send.packets > MAX_PACKETS ||
+	    state->p_read.packets > MAX_PACKETS)
+		return 1;
+
+	/* Rekey after (cipher-specific) maximum blocks */
+	out_blocks = ROUNDUP(outbound_packet_len,
+	    state->newkeys[MODE_OUT]->enc.block_size);
+	return (state->max_blocks_out &&
+	    (state->p_send.blocks + out_blocks > state->max_blocks_out)) ||
+	    (state->max_blocks_in &&
+	    (state->p_read.blocks > state->max_blocks_in));
+}
+
 /*
  * Delayed compression for SSH2 is enabled after authentication:
  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
@@ -1047,6 +1047,20 @@ ssh_packet_enable_delayed_compress(struct ssh *ssh)
 	return 0;
 }
 
+/* Used to mute debug logging for noisy packet types */
+int
+ssh_packet_log_type(u_char type)
+{
+	switch (type) {
+	case SSH2_MSG_CHANNEL_DATA:
+	case SSH2_MSG_CHANNEL_EXTENDED_DATA:
+	case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
+		return 0;
+	default:
+		return 1;
+	}
+}
+
 /*
  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
  */
@@ -1055,7 +1069,7 @@ ssh_packet_send2_wrapped(struct ssh *ssh)
 {
 	struct session_state *state = ssh->state;
 	u_char type, *cp, macbuf[SSH_DIGEST_MAX_LENGTH];
-	u_char padlen, pad = 0;
+	u_char tmp, padlen, pad = 0;
 	u_int authlen = 0, aadlen = 0;
 	u_int len;
 	struct sshenc *enc   = NULL;
@@ -1075,7 +1089,8 @@ ssh_packet_send2_wrapped(struct ssh *ssh)
 	aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
 
 	type = (sshbuf_ptr(state->outgoing_packet))[5];
-
+	if (ssh_packet_log_type(type))
+		debug3("send packet: type %u", type);
 #ifdef PACKET_DEBUG
 	fprintf(stderr, "plain:     ");
 	sshbuf_dump(state->outgoing_packet, stderr);
@@ -1112,19 +1127,29 @@ ssh_packet_send2_wrapped(struct ssh *ssh)
 	if (padlen < 4)
 		padlen += block_size;
 	if (state->extra_pad) {
-		/* will wrap if extra_pad+padlen > 255 */
+		tmp = state->extra_pad;
 		state->extra_pad =
-		    roundup(state->extra_pad, block_size);
-		pad = state->extra_pad -
-		    ((len + padlen) % state->extra_pad);
+		    ROUNDUP(state->extra_pad, block_size);
+		/* check if roundup overflowed */
+		if (state->extra_pad < tmp)
+			return SSH_ERR_INVALID_ARGUMENT;
+		tmp = (len + padlen) % state->extra_pad;
+		/* Check whether pad calculation below will underflow */
+		if (tmp > state->extra_pad)
+			return SSH_ERR_INVALID_ARGUMENT;
+		pad = state->extra_pad - tmp;
 		DBG(debug3("%s: adding %d (len %d padlen %d extra_pad %d)",
 		    __func__, pad, len, padlen, state->extra_pad));
+		tmp = padlen;
 		padlen += pad;
+		/* Check whether padlen calculation overflowed */
+		if (padlen < tmp)
+			return SSH_ERR_INVALID_ARGUMENT; /* overflow */
 		state->extra_pad = 0;
 	}
 	if ((r = sshbuf_reserve(state->outgoing_packet, padlen, &cp)) != 0)
 		goto out;
-	if (enc && !state->send_context.plaintext) {
+	if (enc && !cipher_ctx_is_plaintext(state->send_context)) {
 		/* random padding */
 		arc4random_buf(cp, padlen);
 	} else {
@@ -1156,7 +1181,7 @@ ssh_packet_send2_wrapped(struct ssh *ssh)
 	if ((r = sshbuf_reserve(state->output,
 	    sshbuf_len(state->outgoing_packet) + authlen, &cp)) != 0)
 		goto out;
-	if ((r = cipher_crypt(&state->send_context, state->p_send.seqnr, cp,
+	if ((r = cipher_crypt(state->send_context, state->p_send.seqnr, cp,
 	    sshbuf_ptr(state->outgoing_packet),
 	    len - aadlen, aadlen, authlen)) != 0)
 		goto out;
@@ -1197,34 +1222,58 @@ ssh_packet_send2_wrapped(struct ssh *ssh)
 	return r;
 }
 
+/* returns non-zero if the specified packet type is usec by KEX */
+static int
+ssh_packet_type_is_kex(u_char type)
+{
+	return
+	    type >= SSH2_MSG_TRANSPORT_MIN &&
+	    type <= SSH2_MSG_TRANSPORT_MAX &&
+	    type != SSH2_MSG_SERVICE_REQUEST &&
+	    type != SSH2_MSG_SERVICE_ACCEPT &&
+	    type != SSH2_MSG_EXT_INFO;
+}
+
 int
 ssh_packet_send2(struct ssh *ssh)
 {
 	struct session_state *state = ssh->state;
 	struct packet *p;
 	u_char type;
-	int r;
+	int r, need_rekey;
 
+	if (sshbuf_len(state->outgoing_packet) < 6)
+		return SSH_ERR_INTERNAL_ERROR;
 	type = sshbuf_ptr(state->outgoing_packet)[5];
+	need_rekey = !ssh_packet_type_is_kex(type) &&
+	    ssh_packet_need_rekeying(ssh, sshbuf_len(state->outgoing_packet));
 
-	/* during rekeying we can only send key exchange messages */
-	if (state->rekeying) {
-		if ((type < SSH2_MSG_TRANSPORT_MIN) ||
-		    (type > SSH2_MSG_TRANSPORT_MAX) ||
-		    (type == SSH2_MSG_SERVICE_REQUEST) ||
-		    (type == SSH2_MSG_SERVICE_ACCEPT)) {
-			debug("enqueue packet: %u", type);
-			p = calloc(1, sizeof(*p));
-			if (p == NULL)
-				return SSH_ERR_ALLOC_FAIL;
-			p->type = type;
-			p->payload = state->outgoing_packet;
-			TAILQ_INSERT_TAIL(&state->outgoing, p, next);
-			state->outgoing_packet = sshbuf_new();
-			if (state->outgoing_packet == NULL)
-				return SSH_ERR_ALLOC_FAIL;
-			return 0;
+	/*
+	 * During rekeying we can only send key exchange messages.
+	 * Queue everything else.
+	 */
+	if ((need_rekey || state->rekeying) && !ssh_packet_type_is_kex(type)) {
+		if (need_rekey)
+			debug3("%s: rekex triggered", __func__);
+		debug("enqueue packet: %u", type);
+		p = calloc(1, sizeof(*p));
+		if (p == NULL)
+			return SSH_ERR_ALLOC_FAIL;
+		p->type = type;
+		p->payload = state->outgoing_packet;
+		TAILQ_INSERT_TAIL(&state->outgoing, p, next);
+		state->outgoing_packet = sshbuf_new();
+		if (state->outgoing_packet == NULL)
+			return SSH_ERR_ALLOC_FAIL;
+		if (need_rekey) {
+			/*
+			 * This packet triggered a rekey, so send the
+			 * KEXINIT now.
+			 * NB. reenters this function via kex_start_rekex().
+			 */
+			return kex_start_rekex(ssh);
 		}
+		return 0;
 	}
 
 	/* rekeying starts with sending KEXINIT */
@@ -1240,10 +1289,22 @@ ssh_packet_send2(struct ssh *ssh)
 		state->rekey_time = monotime();
 		while ((p = TAILQ_FIRST(&state->outgoing))) {
 			type = p->type;
+			/*
+			 * If this packet triggers a rekex, then skip the
+			 * remaining packets in the queue for now.
+			 * NB. re-enters this function via kex_start_rekex.
+			 */
+			if (ssh_packet_need_rekeying(ssh,
+			    sshbuf_len(p->payload))) {
+				debug3("%s: queued packet triggered rekex",
+				    __func__);
+				return kex_start_rekex(ssh);
+			}
 			debug("dequeue packet: %u", type);
 			sshbuf_free(state->outgoing_packet);
 			state->outgoing_packet = p->payload;
 			TAILQ_REMOVE(&state->outgoing, p, next);
+			memset(p, 0, sizeof(*p));
 			free(p);
 			if ((r = ssh_packet_send2_wrapped(ssh)) != 0)
 				return r;
@@ -1262,14 +1323,14 @@ int
 ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 {
 	struct session_state *state = ssh->state;
-	int len, r, ms_remain, cont;
+	int len, r, ms_remain;
 	fd_set *setp;
 	char buf[8192];
 	struct timeval timeout, start, *timeoutp = NULL;
 
 	DBG(debug("packet_read()"));
 
-	setp = (fd_set *)calloc(howmany(state->connection_in + 1,
+	setp = calloc(howmany(state->connection_in + 1,
 	    NFDBITS), sizeof(fd_mask));
 	if (setp == NULL)
 		return SSH_ERR_ALLOC_FAIL;
@@ -1279,7 +1340,7 @@ ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 	 * been sent.
 	 */
 	if ((r = ssh_packet_write_wait(ssh)) != 0)
-		return r;
+		goto out;
 
 	/* Stay in the loop until we have received a complete packet. */
 	for (;;) {
@@ -1287,13 +1348,6 @@ ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 		r = ssh_packet_read_poll_seqnr(ssh, typep, seqnr_p);
 		if (r != 0)
 			break;
-		if (!compat20 && (
-		    *typep == SSH_SMSG_SUCCESS
-		    || *typep == SSH_SMSG_FAILURE
-		    || *typep == SSH_CMSG_EOF
-		    || *typep == SSH_CMSG_EXIT_CONFIRMATION))
-			if ((r = sshpkt_get_end(ssh)) != 0)
-				break;
 		/* If we got a packet, return it. */
 		if (*typep != SSH_MSG_NONE)
 			break;
@@ -1311,17 +1365,19 @@ ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 		}
 		/* Wait for some data to arrive. */
 		for (;;) {
-			if (state->packet_timeout_ms != -1) {
+			if (state->packet_timeout_ms > 0) {
 				ms_to_timeval(&timeout, ms_remain);
-				gettimeofday(&start, NULL);
+				monotime_tv(&start);
 			}
 			if ((r = select(state->connection_in + 1, setp,
 			    NULL, NULL, timeoutp)) >= 0)
 				break;
 			if (errno != EAGAIN && errno != EINTR &&
-			    errno != EWOULDBLOCK)
-				break;
-			if (state->packet_timeout_ms == -1)
+			    errno != EWOULDBLOCK) {
+				r = SSH_ERR_SYSTEM_ERROR;
+				goto out;
+			}
+			if (state->packet_timeout_ms <= 0)
 				continue;
 			ms_subtract_diff(&start, &ms_remain);
 			if (ms_remain <= 0) {
@@ -1329,23 +1385,26 @@ ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 				break;
 			}
 		}
-		if (r == 0)
-			return SSH_ERR_CONN_TIMEOUT;
+		if (r == 0) {
+			r = SSH_ERR_CONN_TIMEOUT;
+			goto out;
+		}
 		/* Read data from the socket. */
-		do {
-			cont = 0;
-			len = roaming_read(state->connection_in, buf,
-			    sizeof(buf), &cont);
-		} while (len == 0 && cont);
-		if (len == 0)
-			return SSH_ERR_CONN_CLOSED;
-		if (len < 0)
-			return SSH_ERR_SYSTEM_ERROR;
+		len = read(state->connection_in, buf, sizeof(buf));
+		if (len == 0) {
+			r = SSH_ERR_CONN_CLOSED;
+			goto out;
+		}
+		if (len == -1) {
+			r = SSH_ERR_SYSTEM_ERROR;
+			goto out;
+		}
 
 		/* Append it to the buffer. */
 		if ((r = ssh_packet_process_incoming(ssh, buf, len)) != 0)
-			return r;
+			goto out;
 	}
+ out:
 	free(setp);
 	return r;
 }
@@ -1384,150 +1443,41 @@ ssh_packet_read_expect(struct ssh *ssh, u_int expected_type)
 	return 0;
 }
 
-/* Checks if a full packet is available in the data received so far via
- * packet_process_incoming.  If so, reads the packet; otherwise returns
- * SSH_MSG_NONE.  This does not wait for data from the connection.
- *
- * SSH_MSG_DISCONNECT is handled specially here.  Also,
- * SSH_MSG_IGNORE messages are skipped by this function and are never returned
- * to higher levels.
- */
-
-int
-ssh_packet_read_poll1(struct ssh *ssh, u_char *typep)
+static int
+ssh_packet_read_poll2_mux(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 {
 	struct session_state *state = ssh->state;
-	u_int len, padded_len;
-	const char *emsg;
 	const u_char *cp;
-	u_char *p;
-	u_int checksum, stored_checksum;
+	size_t need;
 	int r;
 
+	if (ssh->kex)
+		return SSH_ERR_INTERNAL_ERROR;
 	*typep = SSH_MSG_NONE;
-
-	/* Check if input size is less than minimum packet size. */
-	if (sshbuf_len(state->input) < 4 + 8)
-		return 0;
-	/* Get length of incoming packet. */
-	len = PEEK_U32(sshbuf_ptr(state->input));
-	if (len < 1 + 2 + 2 || len > 256 * 1024) {
-		if ((r = sshpkt_disconnect(ssh, "Bad packet length %u",
-		    len)) != 0)
-			return r;
-		return SSH_ERR_CONN_CORRUPT;
-	}
-	padded_len = (len + 8) & ~7;
-
-	/* Check if the packet has been entirely received. */
-	if (sshbuf_len(state->input) < 4 + padded_len)
-		return 0;
-
-	/* The entire packet is in buffer. */
-
-	/* Consume packet length. */
-	if ((r = sshbuf_consume(state->input, 4)) != 0)
-		goto out;
-
-	/*
-	 * Cryptographic attack detector for ssh
-	 * (C)1998 CORE-SDI, Buenos Aires Argentina
-	 * Ariel Futoransky(futo@core-sdi.com)
-	 */
-	if (!state->receive_context.plaintext) {
-		emsg = NULL;
-		switch (detect_attack(&state->deattack,
-		    sshbuf_ptr(state->input), padded_len)) {
-		case DEATTACK_OK:
-			break;
-		case DEATTACK_DETECTED:
-			emsg = "crc32 compensation attack detected";
-			break;
-		case DEATTACK_DOS_DETECTED:
-			emsg = "deattack denial of service detected";
-			break;
-		default:
-			emsg = "deattack error";
-			break;
-		}
-		if (emsg != NULL) {
-			error("%s", emsg);
-			if ((r = sshpkt_disconnect(ssh, "%s", emsg)) != 0 ||
-			    (r = ssh_packet_write_wait(ssh)) != 0)
-					return r;
-			return SSH_ERR_CONN_CORRUPT;
-		}
-	}
-
-	/* Decrypt data to incoming_packet. */
+	cp = sshbuf_ptr(state->input);
+	if (state->packlen == 0) {
+		if (sshbuf_len(state->input) < 4 + 1)
+			return 0; /* packet is incomplete */
+		state->packlen = PEEK_U32(cp);
+		if (state->packlen < 4 + 1 ||
+		    state->packlen > PACKET_MAX_SIZE)
+			return SSH_ERR_MESSAGE_INCOMPLETE;
+	}
+	need = state->packlen + 4;
+	if (sshbuf_len(state->input) < need)
+		return 0; /* packet is incomplete */
 	sshbuf_reset(state->incoming_packet);
-	if ((r = sshbuf_reserve(state->incoming_packet, padded_len, &p)) != 0)
-		goto out;
-	if ((r = cipher_crypt(&state->receive_context, 0, p,
-	    sshbuf_ptr(state->input), padded_len, 0, 0)) != 0)
-		goto out;
-
-	if ((r = sshbuf_consume(state->input, padded_len)) != 0)
-		goto out;
-
-#ifdef PACKET_DEBUG
-	fprintf(stderr, "read_poll plain: ");
-	sshbuf_dump(state->incoming_packet, stderr);
-#endif
-
-	/* Compute packet checksum. */
-	checksum = ssh_crc32(sshbuf_ptr(state->incoming_packet),
-	    sshbuf_len(state->incoming_packet) - 4);
-
-	/* Skip padding. */
-	if ((r = sshbuf_consume(state->incoming_packet, 8 - len % 8)) != 0)
-		goto out;
-
-	/* Test check bytes. */
-	if (len != sshbuf_len(state->incoming_packet)) {
-		error("%s: len %d != sshbuf_len %zd", __func__,
-		    len, sshbuf_len(state->incoming_packet));
-		if ((r = sshpkt_disconnect(ssh, "invalid packet length")) != 0 ||
-		    (r = ssh_packet_write_wait(ssh)) != 0)
-			return r;
-		return SSH_ERR_CONN_CORRUPT;
-	}
-
-	cp = sshbuf_ptr(state->incoming_packet) + len - 4;
-	stored_checksum = PEEK_U32(cp);
-	if (checksum != stored_checksum) {
-		error("Corrupted check bytes on input");
-		if ((r = sshpkt_disconnect(ssh, "connection corrupted")) != 0 ||
-		    (r = ssh_packet_write_wait(ssh)) != 0)
-			return r;
-		return SSH_ERR_CONN_CORRUPT;
-	}
-	if ((r = sshbuf_consume_end(state->incoming_packet, 4)) < 0)
-		goto out;
-
-	if (state->packet_compression) {
-		sshbuf_reset(state->compression_buffer);
-		if ((r = uncompress_buffer(ssh, state->incoming_packet,
-		    state->compression_buffer)) != 0)
-			goto out;
-		sshbuf_reset(state->incoming_packet);
-		if ((r = sshbuf_putb(state->incoming_packet,
-		    state->compression_buffer)) != 0)
-			goto out;
-	}
-	state->p_read.packets++;
-	state->p_read.bytes += padded_len + 4;
-	if ((r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
-		goto out;
-	if (*typep < SSH_MSG_MIN || *typep > SSH_MSG_MAX) {
-		error("Invalid ssh1 packet type: %d", *typep);
-		if ((r = sshpkt_disconnect(ssh, "invalid packet type")) != 0 ||
-		    (r = ssh_packet_write_wait(ssh)) != 0)
-			return r;
-		return SSH_ERR_PROTOCOL_ERROR;
-	}
-	r = 0;
- out:
+	if ((r = sshbuf_put(state->incoming_packet, cp + 4,
+	    state->packlen)) != 0 ||
+	    (r = sshbuf_consume(state->input, need)) != 0 ||
+	    (r = sshbuf_get_u8(state->incoming_packet, NULL)) != 0 ||
+	    (r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
+		return r;
+	if (ssh_packet_log_type(*typep))
+		debug3("%s: type %u", __func__, *typep);
+	/* sshbuf_dump(state->incoming_packet, stderr); */
+	/* reset for next packet */
+	state->packlen = 0;
 	return r;
 }
 
@@ -1536,13 +1486,16 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 {
 	struct session_state *state = ssh->state;
 	u_int padlen, need;
-	u_char *cp, macbuf[SSH_DIGEST_MAX_LENGTH];
+	u_char *cp;
 	u_int maclen, aadlen = 0, authlen = 0, block_size;
 	struct sshenc *enc   = NULL;
 	struct sshmac *mac   = NULL;
 	struct sshcomp *comp = NULL;
 	int r;
 
+	if (state->mux)
+		return ssh_packet_read_poll2_mux(ssh, typep, seqnr_p);
+
 	*typep = SSH_MSG_NONE;
 
 	if (state->packet_discard)
@@ -1561,7 +1514,7 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 	aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
 
 	if (aadlen && state->packlen == 0) {
-		if (cipher_get_length(&state->receive_context,
+		if (cipher_get_length(state->receive_context,
 		    &state->packlen, state->p_read.seqnr,
 		    sshbuf_ptr(state->input), sshbuf_len(state->input)) != 0)
 			return 0;
@@ -1573,6 +1526,7 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 			logit("Bad packet length %u.", state->packlen);
 			if ((r = sshpkt_disconnect(ssh, "Packet corrupt")) != 0)
 				return r;
+			return SSH_ERR_CONN_CORRUPT;
 		}
 		sshbuf_reset(state->incoming_packet);
 	} else if (state->packlen == 0) {
@@ -1586,7 +1540,7 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 		if ((r = sshbuf_reserve(state->incoming_packet, block_size,
 		    &cp)) != 0)
 			goto out;
-		if ((r = cipher_crypt(&state->receive_context,
+		if ((r = cipher_crypt(state->receive_context,
 		    state->p_send.seqnr, cp, sshbuf_ptr(state->input),
 		    block_size, 0, 0)) != 0)
 			goto out;
@@ -1600,8 +1554,8 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 			sshbuf_dump(state->incoming_packet, stderr);
 #endif
 			logit("Bad packet length %u.", state->packlen);
-			return ssh_packet_start_discard(ssh, enc, mac,
-			    state->packlen, PACKET_MAX_SIZE);
+			return ssh_packet_start_discard(ssh, enc, mac, 0,
+			    PACKET_MAX_SIZE);
 		}
 		if ((r = sshbuf_consume(state->input, block_size)) != 0)
 			goto out;
@@ -1623,8 +1577,8 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 	if (need % block_size != 0) {
 		logit("padding error: need %d block %d mod %d",
 		    need, block_size, need % block_size);
-		return ssh_packet_start_discard(ssh, enc, mac,
-		    state->packlen, PACKET_MAX_SIZE - block_size);
+		return ssh_packet_start_discard(ssh, enc, mac, 0,
+		    PACKET_MAX_SIZE - block_size);
 	}
 	/*
 	 * check if the entire packet has been received and
@@ -1635,46 +1589,46 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 	 * 'maclen' bytes of message authentication code.
 	 */
 	if (sshbuf_len(state->input) < aadlen + need + authlen + maclen)
-		return 0;
+		return 0; /* packet is incomplete */
 #ifdef PACKET_DEBUG
 	fprintf(stderr, "read_poll enc/full: ");
 	sshbuf_dump(state->input, stderr);
 #endif
-	/* EtM: compute mac over encrypted input */
+	/* EtM: check mac over encrypted input */
 	if (mac && mac->enabled && mac->etm) {
-		if ((r = mac_compute(mac, state->p_read.seqnr,
+		if ((r = mac_check(mac, state->p_read.seqnr,
 		    sshbuf_ptr(state->input), aadlen + need,
-		    macbuf, sizeof(macbuf))) != 0)
+		    sshbuf_ptr(state->input) + aadlen + need + authlen,
+		    maclen)) != 0) {
+			if (r == SSH_ERR_MAC_INVALID)
+				logit("Corrupted MAC on input.");
 			goto out;
+		}
 	}
 	if ((r = sshbuf_reserve(state->incoming_packet, aadlen + need,
 	    &cp)) != 0)
 		goto out;
-	if ((r = cipher_crypt(&state->receive_context, state->p_read.seqnr, cp,
+	if ((r = cipher_crypt(state->receive_context, state->p_read.seqnr, cp,
 	    sshbuf_ptr(state->input), need, aadlen, authlen)) != 0)
 		goto out;
 	if ((r = sshbuf_consume(state->input, aadlen + need + authlen)) != 0)
 		goto out;
-	/*
-	 * compute MAC over seqnr and packet,
-	 * increment sequence number for incoming packet
-	 */
 	if (mac && mac->enabled) {
-		if (!mac->etm)
-			if ((r = mac_compute(mac, state->p_read.seqnr,
-			    sshbuf_ptr(state->incoming_packet),
-			    sshbuf_len(state->incoming_packet),
-			    macbuf, sizeof(macbuf))) != 0)
+		/* Not EtM: check MAC over cleartext */
+		if (!mac->etm && (r = mac_check(mac, state->p_read.seqnr,
+		    sshbuf_ptr(state->incoming_packet),
+		    sshbuf_len(state->incoming_packet),
+		    sshbuf_ptr(state->input), maclen)) != 0) {
+			if (r != SSH_ERR_MAC_INVALID)
 				goto out;
-		if (timingsafe_bcmp(macbuf, sshbuf_ptr(state->input),
-		    mac->mac_len) != 0) {
 			logit("Corrupted MAC on input.");
-			if (need > PACKET_MAX_SIZE)
+			if (need + block_size > PACKET_MAX_SIZE)
 				return SSH_ERR_INTERNAL_ERROR;
 			return ssh_packet_start_discard(ssh, enc, mac,
-			    state->packlen, PACKET_MAX_SIZE - need);
+			    sshbuf_len(state->incoming_packet),
+			    PACKET_MAX_SIZE - need - block_size);
 		}
-
+		/* Remove MAC from input buffer */
 		DBG(debug("MAC #%d ok", state->p_read.seqnr));
 		if ((r = sshbuf_consume(state->input, mac->mac_len)) != 0)
 			goto out;
@@ -1725,6 +1679,8 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 	 */
 	if ((r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
 		goto out;
+	if (ssh_packet_log_type(*typep))
+		debug3("receive packet: type %u", *typep);
 	if (*typep < SSH2_MSG_MIN || *typep >= SSH2_MSG_LOCAL_MIN) {
 		if ((r = sshpkt_disconnect(ssh,
 		    "Invalid ssh2 packet type: %d", *typep)) != 0 ||
@@ -1732,9 +1688,11 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 			return r;
 		return SSH_ERR_PROTOCOL_ERROR;
 	}
-	if (*typep == SSH2_MSG_NEWKEYS)
-		r = ssh_set_newkeys(ssh, MODE_IN);
-	else if (*typep == SSH2_MSG_USERAUTH_SUCCESS && !state->server_side)
+	if (state->hook_in != NULL &&
+	    (r = state->hook_in(ssh, state->incoming_packet, typep,
+	    state->hook_in_ctx)) != 0)
+		return r;
+	if (*typep == SSH2_MSG_USERAUTH_SUCCESS && !state->server_side)
 		r = ssh_packet_enable_delayed_compress(ssh);
 	else
 		r = 0;
@@ -1744,6 +1702,13 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 #endif
 	/* reset for next packet */
 	state->packlen = 0;
+
+	/* do we need to rekey? */
+	if (ssh_packet_need_rekeying(ssh, 0)) {
+		debug3("%s: rekex triggered", __func__);
+		if ((r = kex_start_rekex(ssh)) != 0)
+			return r;
+	}
  out:
 	return r;
 }
@@ -1758,74 +1723,48 @@ ssh_packet_read_poll_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 
 	for (;;) {
 		msg = NULL;
-		if (compat20) {
-			r = ssh_packet_read_poll2(ssh, typep, seqnr_p);
-			if (r != 0)
-				return r;
-			if (*typep) {
-				state->keep_alive_timeouts = 0;
-				DBG(debug("received packet type %d", *typep));
-			}
-			switch (*typep) {
-			case SSH2_MSG_IGNORE:
-				debug3("Received SSH2_MSG_IGNORE");
-				break;
-			case SSH2_MSG_DEBUG:
-				if ((r = sshpkt_get_u8(ssh, NULL)) != 0 ||
-				    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
-				    (r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
-					if (msg)
-						free(msg);
-					return r;
-				}
-				debug("Remote: %.900s", msg);
-				free(msg);
-				break;
-			case SSH2_MSG_DISCONNECT:
-				if ((r = sshpkt_get_u32(ssh, &reason)) != 0 ||
-				    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
-					return r;
-				/* Ignore normal client exit notifications */
-				do_log2(ssh->state->server_side &&
-				    reason == SSH2_DISCONNECT_BY_APPLICATION ?
-				    SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR,
-				    "Received disconnect from %s: %u: %.400s",
-				    ssh_remote_ipaddr(ssh), reason, msg);
-				free(msg);
-				return SSH_ERR_DISCONNECTED;
-			case SSH2_MSG_UNIMPLEMENTED:
-				if ((r = sshpkt_get_u32(ssh, &seqnr)) != 0)
-					return r;
-				debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
-				    seqnr);
-				break;
-			default:
-				return 0;
-			}
-		} else {
-			r = ssh_packet_read_poll1(ssh, typep);
-			switch (*typep) {
-			case SSH_MSG_NONE:
-				return SSH_MSG_NONE;
-			case SSH_MSG_IGNORE:
-				break;
-			case SSH_MSG_DEBUG:
-				if ((r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
-					return r;
-				debug("Remote: %.900s", msg);
-				free(msg);
-				break;
-			case SSH_MSG_DISCONNECT:
-				if ((r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
-					return r;
-				error("Received disconnect from %s: %.400s",
-				    ssh_remote_ipaddr(ssh), msg);
+		r = ssh_packet_read_poll2(ssh, typep, seqnr_p);
+		if (r != 0)
+			return r;
+		if (*typep) {
+			state->keep_alive_timeouts = 0;
+			DBG(debug("received packet type %d", *typep));
+		}
+		switch (*typep) {
+		case SSH2_MSG_IGNORE:
+			debug3("Received SSH2_MSG_IGNORE");
+			break;
+		case SSH2_MSG_DEBUG:
+			if ((r = sshpkt_get_u8(ssh, NULL)) != 0 ||
+			    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
+			    (r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
 				free(msg);
-				return SSH_ERR_DISCONNECTED;
-			default:
-				DBG(debug("received packet type %d", *typep));
-				return 0;
+				return r;
 			}
+			debug("Remote: %.900s", msg);
+			free(msg);
+			break;
+		case SSH2_MSG_DISCONNECT:
+			if ((r = sshpkt_get_u32(ssh, &reason)) != 0 ||
+			    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
+				return r;
+			/* Ignore normal client exit notifications */
+			do_log2(ssh->state->server_side &&
+			    reason == SSH2_DISCONNECT_BY_APPLICATION ?
+			    SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR,
+			    "Received disconnect from %s port %d:"
+			    "%u: %.400s", ssh_remote_ipaddr(ssh),
+			    ssh_remote_port(ssh), reason, msg);
+			free(msg);
+			return SSH_ERR_DISCONNECTED;
+		case SSH2_MSG_UNIMPLEMENTED:
+			if ((r = sshpkt_get_u32(ssh, &seqnr)) != 0)
+				return r;
+			debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
+			    seqnr);
+			break;
+		default:
+			return 0;
 		}
 	}
 }
@@ -1877,51 +1816,101 @@ ssh_packet_send_debug(struct ssh *ssh, const char *fmt,...)
 	va_list args;
 	int r;
 
-	if (compat20 && (ssh->compat & SSH_BUG_DEBUG))
+	if ((ssh->compat & SSH_BUG_DEBUG))
 		return;
 
 	va_start(args, fmt);
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 
-	if (compat20) {
-		if ((r = sshpkt_start(ssh, SSH2_MSG_DEBUG)) != 0 ||
-		    (r = sshpkt_put_u8(ssh, 0)) != 0 || /* always display */
-		    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
-		    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
-		    (r = sshpkt_send(ssh)) != 0)
-			fatal("%s: %s", __func__, ssh_err(r));
-	} else {
-		if ((r = sshpkt_start(ssh, SSH_MSG_DEBUG)) != 0 ||
-		    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
-		    (r = sshpkt_send(ssh)) != 0)
-			fatal("%s: %s", __func__, ssh_err(r));
-	}
-	if ((r = ssh_packet_write_wait(ssh)) != 0)
+	debug3("sending debug message: %s", buf);
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_DEBUG)) != 0 ||
+	    (r = sshpkt_put_u8(ssh, 0)) != 0 || /* always display */
+	    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0 ||
+	    (r = ssh_packet_write_wait(ssh)) != 0)
 		fatal("%s: %s", __func__, ssh_err(r));
 }
 
+void
+sshpkt_fmt_connection_id(struct ssh *ssh, char *s, size_t l)
+{
+	snprintf(s, l, "%.200s%s%s port %d",
+	    ssh->log_preamble ? ssh->log_preamble : "",
+	    ssh->log_preamble ? " " : "",
+	    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+}
+
 /*
  * Pretty-print connection-terminating errors and exit.
  */
-void
-sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
+static void
+sshpkt_vfatal(struct ssh *ssh, int r, const char *fmt, va_list ap)
 {
+	char *tag = NULL, remote_id[512];
+	int oerrno = errno;
+
+	sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
+
 	switch (r) {
 	case SSH_ERR_CONN_CLOSED:
-		logit("Connection closed by %.200s", ssh_remote_ipaddr(ssh));
-		cleanup_exit(255);
+		ssh_packet_clear_keys(ssh);
+		logdie("Connection closed by %s", remote_id);
 	case SSH_ERR_CONN_TIMEOUT:
-		logit("Connection to %.200s timed out while "
-		    "waiting to write", ssh_remote_ipaddr(ssh));
-		cleanup_exit(255);
+		ssh_packet_clear_keys(ssh);
+		logdie("Connection %s %s timed out",
+		    ssh->state->server_side ? "from" : "to", remote_id);
+	case SSH_ERR_DISCONNECTED:
+		ssh_packet_clear_keys(ssh);
+		logdie("Disconnected from %s", remote_id);
+	case SSH_ERR_SYSTEM_ERROR:
+		if (errno == ECONNRESET) {
+			ssh_packet_clear_keys(ssh);
+			logdie("Connection reset by %s", remote_id);
+		}
+		/* FALLTHROUGH */
+	case SSH_ERR_NO_CIPHER_ALG_MATCH:
+	case SSH_ERR_NO_MAC_ALG_MATCH:
+	case SSH_ERR_NO_COMPRESS_ALG_MATCH:
+	case SSH_ERR_NO_KEX_ALG_MATCH:
+	case SSH_ERR_NO_HOSTKEY_ALG_MATCH:
+		if (ssh && ssh->kex && ssh->kex->failed_choice) {
+			ssh_packet_clear_keys(ssh);
+			errno = oerrno;
+			logdie("Unable to negotiate with %s: %s. "
+			    "Their offer: %s", remote_id, ssh_err(r),
+			    ssh->kex->failed_choice);
+		}
+		/* FALLTHROUGH */
 	default:
-		fatal("%s%sConnection to %.200s: %s",
+		if (vasprintf(&tag, fmt, ap) == -1) {
+			ssh_packet_clear_keys(ssh);
+			logdie("%s: could not allocate failure message",
+			    __func__);
+		}
+		ssh_packet_clear_keys(ssh);
+		errno = oerrno;
+		logdie("%s%sConnection %s %s: %s",
 		    tag != NULL ? tag : "", tag != NULL ? ": " : "",
-		    ssh_remote_ipaddr(ssh), ssh_err(r));
+		    ssh->state->server_side ? "from" : "to",
+		    remote_id, ssh_err(r));
 	}
 }
 
+void
+sshpkt_fatal(struct ssh *ssh, int r, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	sshpkt_vfatal(ssh, r, fmt, ap);
+	/* NOTREACHED */
+	va_end(ap);
+	logdie("%s: should have exited", __func__);
+}
+
 /*
  * Logs the error plus constructs and sends a disconnect packet, closes the
  * connection, and exits.  This function never returns. The error message
@@ -1931,7 +1920,7 @@ sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
 void
 ssh_packet_disconnect(struct ssh *ssh, const char *fmt,...)
 {
-	char buf[1024];
+	char buf[1024], remote_id[512];
 	va_list args;
 	static int disconnecting = 0;
 	int r;
@@ -1944,22 +1933,23 @@ ssh_packet_disconnect(struct ssh *ssh, const char *fmt,...)
 	 * Format the message.  Note that the caller must make sure the
 	 * message is of limited size.
 	 */
+	sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
 	va_start(args, fmt);
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 
 	/* Display the error locally */
-	logit("Disconnecting: %.100s", buf);
+	logit("Disconnecting %s: %.100s", remote_id, buf);
 
 	/*
 	 * Send the disconnect message to the other side, and wait
 	 * for it to get sent.
 	 */
 	if ((r = sshpkt_disconnect(ssh, "%s", buf)) != 0)
-		sshpkt_fatal(ssh, __func__, r);
+		sshpkt_fatal(ssh, r, "%s", __func__);
 
 	if ((r = ssh_packet_write_wait(ssh)) != 0)
-		sshpkt_fatal(ssh, __func__, r);
+		sshpkt_fatal(ssh, r, "%s", __func__);
 
 	/* Close the connection. */
 	ssh_packet_close(ssh);
@@ -1975,19 +1965,18 @@ ssh_packet_write_poll(struct ssh *ssh)
 {
 	struct session_state *state = ssh->state;
 	int len = sshbuf_len(state->output);
-	int cont, r;
+	int r;
 
 	if (len > 0) {
-		cont = 0;
-		len = roaming_write(state->connection_out,
-		    sshbuf_ptr(state->output), len, &cont);
+		len = write(state->connection_out,
+		    sshbuf_ptr(state->output), len);
 		if (len == -1) {
 			if (errno == EINTR || errno == EAGAIN ||
 			    errno == EWOULDBLOCK)
 				return 0;
 			return SSH_ERR_SYSTEM_ERROR;
 		}
-		if (len == 0 && !cont)
+		if (len == 0)
 			return SSH_ERR_CONN_CLOSED;
 		if ((r = sshbuf_consume(state->output, len)) != 0)
 			return r;
@@ -2007,11 +1996,14 @@ ssh_packet_write_wait(struct ssh *ssh)
 	struct timeval start, timeout, *timeoutp = NULL;
 	struct session_state *state = ssh->state;
 
-	setp = (fd_set *)calloc(howmany(state->connection_out + 1,
+	setp = calloc(howmany(state->connection_out + 1,
 	    NFDBITS), sizeof(fd_mask));
 	if (setp == NULL)
 		return SSH_ERR_ALLOC_FAIL;
-	ssh_packet_write_poll(ssh);
+	if ((r = ssh_packet_write_poll(ssh)) != 0) {
+		free(setp);
+		return r;
+	}
 	while (ssh_packet_have_data_to_write(ssh)) {
 		memset(setp, 0, howmany(state->connection_out + 1,
 		    NFDBITS) * sizeof(fd_mask));
@@ -2022,9 +2014,9 @@ ssh_packet_write_wait(struct ssh *ssh)
 			timeoutp = &timeout;
 		}
 		for (;;) {
-			if (state->packet_timeout_ms != -1) {
+			if (state->packet_timeout_ms > 0) {
 				ms_to_timeval(&timeout, ms_remain);
-				gettimeofday(&start, NULL);
+				monotime_tv(&start);
 			}
 			if ((ret = select(state->connection_out + 1,
 			    NULL, setp, NULL, timeoutp)) >= 0)
@@ -2032,7 +2024,7 @@ ssh_packet_write_wait(struct ssh *ssh)
 			if (errno != EAGAIN && errno != EINTR &&
 			    errno != EWOULDBLOCK)
 				break;
-			if (state->packet_timeout_ms == -1)
+			if (state->packet_timeout_ms <= 0)
 				continue;
 			ms_subtract_diff(&start, &ms_remain);
 			if (ms_remain <= 0) {
@@ -2076,14 +2068,14 @@ void
 ssh_packet_set_tos(struct ssh *ssh, int tos)
 {
 #ifndef IP_TOS_IS_BROKEN
-	if (!ssh_packet_connection_is_on_socket(ssh))
+	if (!ssh_packet_connection_is_on_socket(ssh) || tos == INT_MAX)
 		return;
 	switch (ssh_packet_connection_af(ssh)) {
 # ifdef IP_TOS
 	case AF_INET:
 		debug3("%s: set IP_TOS 0x%02x", __func__, tos);
 		if (setsockopt(ssh->state->connection_in,
-		    IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0)
+		    IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) == -1)
 			error("setsockopt IP_TOS %d: %.100s:",
 			    tos, strerror(errno));
 		break;
@@ -2092,7 +2084,7 @@ ssh_packet_set_tos(struct ssh *ssh, int tos)
 	case AF_INET6:
 		debug3("%s: set IPV6_TCLASS 0x%02x", __func__, tos);
 		if (setsockopt(ssh->state->connection_in,
-		    IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) < 0)
+		    IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) == -1)
 			error("setsockopt IPV6_TCLASS %d: %.100s:",
 			    tos, strerror(errno));
 		break;
@@ -2169,60 +2161,11 @@ ssh_packet_get_maxsize(struct ssh *ssh)
 	return ssh->state->max_packet_size;
 }
 
-/*
- * 9.2.  Ignored Data Message
- *
- *   byte      SSH_MSG_IGNORE
- *   string    data
- *
- * All implementations MUST understand (and ignore) this message at any
- * time (after receiving the protocol version). No implementation is
- * required to send them. This message can be used as an additional
- * protection measure against advanced traffic analysis techniques.
- */
 void
-ssh_packet_send_ignore(struct ssh *ssh, int nbytes)
+ssh_packet_set_rekey_limits(struct ssh *ssh, u_int64_t bytes, u_int32_t seconds)
 {
-	u_int32_t rnd = 0;
-	int r, i;
-
-	if ((r = sshpkt_start(ssh, compat20 ?
-	    SSH2_MSG_IGNORE : SSH_MSG_IGNORE)) != 0 ||
-	    (r = sshpkt_put_u32(ssh, nbytes)) != 0)
-		fatal("%s: %s", __func__, ssh_err(r));
-	for (i = 0; i < nbytes; i++) {
-		if (i % 4 == 0)
-			rnd = arc4random();
-		if ((r = sshpkt_put_u8(ssh, (u_char)rnd & 0xff)) != 0)
-			fatal("%s: %s", __func__, ssh_err(r));
-		rnd >>= 8;
-	}
-}
-
-#define MAX_PACKETS	(1U<<31)
-int
-ssh_packet_need_rekeying(struct ssh *ssh)
-{
-	struct session_state *state = ssh->state;
-
-	if (ssh->compat & SSH_BUG_NOREKEY)
-		return 0;
-	return
-	    (state->p_send.packets > MAX_PACKETS) ||
-	    (state->p_read.packets > MAX_PACKETS) ||
-	    (state->max_blocks_out &&
-	        (state->p_send.blocks > state->max_blocks_out)) ||
-	    (state->max_blocks_in &&
-	        (state->p_read.blocks > state->max_blocks_in)) ||
-	    (state->rekey_interval != 0 && state->rekey_time +
-		 state->rekey_interval <= monotime());
-}
-
-void
-ssh_packet_set_rekey_limits(struct ssh *ssh, u_int32_t bytes, time_t seconds)
-{
-	debug3("rekey after %lld bytes, %d seconds", (long long)bytes,
-	    (int)seconds);
+	debug3("rekey after %llu bytes, %u seconds", (unsigned long long)bytes,
+	    (unsigned int)seconds);
 	ssh->state->rekey_limit = bytes;
 	ssh->state->rekey_interval = seconds;
 }
@@ -2241,6 +2184,7 @@ void
 ssh_packet_set_server(struct ssh *ssh)
 {
 	ssh->state->server_side = 1;
+	ssh->kex->server = 1; /* XXX unify? */
 }
 
 void
@@ -2261,77 +2205,18 @@ ssh_packet_get_output(struct ssh *ssh)
 	return (void *)ssh->state->output;
 }
 
-/* XXX TODO update roaming to new API (does not work anyway) */
-/*
- * Save the state for the real connection, and use a separate state when
- * resuming a suspended connection.
- */
-void
-ssh_packet_backup_state(struct ssh *ssh,
-    struct ssh *backup_state)
-{
-	struct ssh *tmp;
-
-	close(ssh->state->connection_in);
-	ssh->state->connection_in = -1;
-	close(ssh->state->connection_out);
-	ssh->state->connection_out = -1;
-	if (backup_state)
-		tmp = backup_state;
-	else
-		tmp = ssh_alloc_session_state();
-	backup_state = ssh;
-	ssh = tmp;
-}
-
-/* XXX FIXME FIXME FIXME */
-/*
- * Swap in the old state when resuming a connecion.
- */
-void
-ssh_packet_restore_state(struct ssh *ssh,
-    struct ssh *backup_state)
-{
-	struct ssh *tmp;
-	u_int len;
-	int r;
-
-	tmp = backup_state;
-	backup_state = ssh;
-	ssh = tmp;
-	ssh->state->connection_in = backup_state->state->connection_in;
-	backup_state->state->connection_in = -1;
-	ssh->state->connection_out = backup_state->state->connection_out;
-	backup_state->state->connection_out = -1;
-	len = sshbuf_len(backup_state->state->input);
-	if (len > 0) {
-		if ((r = sshbuf_putb(ssh->state->input,
-		    backup_state->state->input)) != 0)
-			fatal("%s: %s", __func__, ssh_err(r));
-		sshbuf_reset(backup_state->state->input);
-		add_recv_bytes(len);
-	}
-}
-
 /* Reset after_authentication and reset compression in post-auth privsep */
 static int
 ssh_packet_set_postauth(struct ssh *ssh)
 {
-	struct sshcomp *comp;
-	int r, mode;
+	int r;
 
 	debug("%s: called", __func__);
 	/* This was set in net child, but is not visible in user child */
 	ssh->state->after_authentication = 1;
 	ssh->state->rekeying = 0;
-	for (mode = 0; mode < MODE_MAX; mode++) {
-		if (ssh->state->newkeys[mode] == NULL)
-			continue;
-		comp = &ssh->state->newkeys[mode]->comp;
-		if (comp && comp->enabled &&
-		    (r = ssh_packet_init_compression(ssh)) != 0)
-			return r;
-	}
+	if ((r = ssh_packet_enable_delayed_compress(ssh)) != 0)
+		return r;
 	return 0;
 }
 
@@ -2346,13 +2231,15 @@ kex_to_blob(struct sshbuf *m, struct kex *kex)
 	if ((r = sshbuf_put_string(m, kex->session_id,
 	    kex->session_id_len)) != 0 ||
 	    (r = sshbuf_put_u32(m, kex->we_need)) != 0 ||
+	    (r = sshbuf_put_cstring(m, kex->hostkey_alg)) != 0 ||
 	    (r = sshbuf_put_u32(m, kex->hostkey_type)) != 0 ||
+	    (r = sshbuf_put_u32(m, kex->hostkey_nid)) != 0 ||
 	    (r = sshbuf_put_u32(m, kex->kex_type)) != 0 ||
 	    (r = sshbuf_put_stringb(m, kex->my)) != 0 ||
 	    (r = sshbuf_put_stringb(m, kex->peer)) != 0 ||
-	    (r = sshbuf_put_u32(m, kex->flags)) != 0 ||
-	    (r = sshbuf_put_cstring(m, kex->client_version_string)) != 0 ||
-	    (r = sshbuf_put_cstring(m, kex->server_version_string)) != 0)
+	    (r = sshbuf_put_stringb(m, kex->client_version)) != 0 ||
+	    (r = sshbuf_put_stringb(m, kex->server_version)) != 0 ||
+	    (r = sshbuf_put_u32(m, kex->flags)) != 0)
 		return r;
 	return 0;
 }
@@ -2374,15 +2261,13 @@ newkeys_to_blob(struct sshbuf *m, struct ssh *ssh, int mode)
 	enc = &newkey->enc;
 	mac = &newkey->mac;
 	comp = &newkey->comp;
-	cc = (mode == MODE_OUT) ? &ssh->state->send_context :
-	    &ssh->state->receive_context;
+	cc = (mode == MODE_OUT) ? ssh->state->send_context :
+	    ssh->state->receive_context;
 	if ((r = cipher_get_keyiv(cc, enc->iv, enc->iv_len)) != 0)
 		return r;
 	if ((b = sshbuf_new()) == NULL)
 		return SSH_ERR_ALLOC_FAIL;
-	/* The cipher struct is constant and shared, you export pointer */
 	if ((r = sshbuf_put_cstring(b, enc->name)) != 0 ||
-	    (r = sshbuf_put(b, &enc->cipher, sizeof(enc->cipher))) != 0 ||
 	    (r = sshbuf_put_u32(b, enc->enabled)) != 0 ||
 	    (r = sshbuf_put_u32(b, enc->block_size)) != 0 ||
 	    (r = sshbuf_put_string(b, enc->key, enc->key_len)) != 0 ||
@@ -2395,13 +2280,11 @@ newkeys_to_blob(struct sshbuf *m, struct ssh *ssh, int mode)
 			goto out;
 	}
 	if ((r = sshbuf_put_u32(b, comp->type)) != 0 ||
-	    (r = sshbuf_put_u32(b, comp->enabled)) != 0 ||
 	    (r = sshbuf_put_cstring(b, comp->name)) != 0)
 		goto out;
 	r = sshbuf_put_stringb(m, b);
  out:
-	if (b != NULL)
-		sshbuf_free(b);
+	sshbuf_free(b);
 	return r;
 }
 
@@ -2410,64 +2293,25 @@ int
 ssh_packet_get_state(struct ssh *ssh, struct sshbuf *m)
 {
 	struct session_state *state = ssh->state;
-	u_char *p;
-	size_t slen, rlen;
-	int r, ssh1cipher;
-
-	if (!compat20) {
-		ssh1cipher = cipher_get_number(state->receive_context.cipher);
-		slen = cipher_get_keyiv_len(&state->send_context);
-		rlen = cipher_get_keyiv_len(&state->receive_context);
-		if ((r = sshbuf_put_u32(m, state->remote_protocol_flags)) != 0 ||
-		    (r = sshbuf_put_u32(m, ssh1cipher)) != 0 ||
-		    (r = sshbuf_put_string(m, state->ssh1_key, state->ssh1_keylen)) != 0 ||
-		    (r = sshbuf_put_u32(m, slen)) != 0 ||
-		    (r = sshbuf_reserve(m, slen, &p)) != 0 ||
-		    (r = cipher_get_keyiv(&state->send_context, p, slen)) != 0 ||
-		    (r = sshbuf_put_u32(m, rlen)) != 0 ||
-		    (r = sshbuf_reserve(m, rlen, &p)) != 0 ||
-		    (r = cipher_get_keyiv(&state->receive_context, p, rlen)) != 0)
-			return r;
-	} else {
-		if ((r = kex_to_blob(m, ssh->kex)) != 0 ||
-		    (r = newkeys_to_blob(m, ssh, MODE_OUT)) != 0 ||
-		    (r = newkeys_to_blob(m, ssh, MODE_IN)) != 0 ||
-		    (r = sshbuf_put_u32(m, state->rekey_limit)) != 0 ||
-		    (r = sshbuf_put_u32(m, state->rekey_interval)) != 0 ||
-		    (r = sshbuf_put_u32(m, state->p_send.seqnr)) != 0 ||
-		    (r = sshbuf_put_u64(m, state->p_send.blocks)) != 0 ||
-		    (r = sshbuf_put_u32(m, state->p_send.packets)) != 0 ||
-		    (r = sshbuf_put_u64(m, state->p_send.bytes)) != 0 ||
-		    (r = sshbuf_put_u32(m, state->p_read.seqnr)) != 0 ||
-		    (r = sshbuf_put_u64(m, state->p_read.blocks)) != 0 ||
-		    (r = sshbuf_put_u32(m, state->p_read.packets)) != 0 ||
-		    (r = sshbuf_put_u64(m, state->p_read.bytes)) != 0)
-			return r;
-	}
-
-	slen = cipher_get_keycontext(&state->send_context, NULL);
-	rlen = cipher_get_keycontext(&state->receive_context, NULL);
-	if ((r = sshbuf_put_u32(m, slen)) != 0 ||
-	    (r = sshbuf_reserve(m, slen, &p)) != 0)
-		return r;
-	if (cipher_get_keycontext(&state->send_context, p) != (int)slen)
-		return SSH_ERR_INTERNAL_ERROR;
-	if ((r = sshbuf_put_u32(m, rlen)) != 0 ||
-	    (r = sshbuf_reserve(m, rlen, &p)) != 0)
-		return r;
-	if (cipher_get_keycontext(&state->receive_context, p) != (int)rlen)
-		return SSH_ERR_INTERNAL_ERROR;
+	int r;
 
-	if ((r = ssh_packet_get_compress_state(m, ssh)) != 0 ||
+	if ((r = kex_to_blob(m, ssh->kex)) != 0 ||
+	    (r = newkeys_to_blob(m, ssh, MODE_OUT)) != 0 ||
+	    (r = newkeys_to_blob(m, ssh, MODE_IN)) != 0 ||
+	    (r = sshbuf_put_u64(m, state->rekey_limit)) != 0 ||
+	    (r = sshbuf_put_u32(m, state->rekey_interval)) != 0 ||
+	    (r = sshbuf_put_u32(m, state->p_send.seqnr)) != 0 ||
+	    (r = sshbuf_put_u64(m, state->p_send.blocks)) != 0 ||
+	    (r = sshbuf_put_u32(m, state->p_send.packets)) != 0 ||
+	    (r = sshbuf_put_u64(m, state->p_send.bytes)) != 0 ||
+	    (r = sshbuf_put_u32(m, state->p_read.seqnr)) != 0 ||
+	    (r = sshbuf_put_u64(m, state->p_read.blocks)) != 0 ||
+	    (r = sshbuf_put_u32(m, state->p_read.packets)) != 0 ||
+	    (r = sshbuf_put_u64(m, state->p_read.bytes)) != 0 ||
 	    (r = sshbuf_put_stringb(m, state->input)) != 0 ||
 	    (r = sshbuf_put_stringb(m, state->output)) != 0)
 		return r;
 
-	if (compat20) {
-		if ((r = sshbuf_put_u64(m, get_sent_bytes())) != 0 ||
-		    (r = sshbuf_put_u64(m, get_recv_bytes())) != 0)
-			return r;
-	}
 	return 0;
 }
 
@@ -2497,12 +2341,15 @@ newkeys_from_blob(struct sshbuf *m, struct ssh *ssh, int mode)
 	comp = &newkey->comp;
 
 	if ((r = sshbuf_get_cstring(b, &enc->name, NULL)) != 0 ||
-	    (r = sshbuf_get(b, &enc->cipher, sizeof(enc->cipher))) != 0 ||
 	    (r = sshbuf_get_u32(b, (u_int *)&enc->enabled)) != 0 ||
 	    (r = sshbuf_get_u32(b, &enc->block_size)) != 0 ||
 	    (r = sshbuf_get_string(b, &enc->key, &keylen)) != 0 ||
 	    (r = sshbuf_get_string(b, &enc->iv, &ivlen)) != 0)
 		goto out;
+	if ((enc->cipher = cipher_by_name(enc->name)) == NULL) {
+		r = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
 	if (cipher_authlen(enc->cipher) == 0) {
 		if ((r = sshbuf_get_cstring(b, &mac->name, NULL)) != 0)
 			goto out;
@@ -2518,14 +2365,8 @@ newkeys_from_blob(struct sshbuf *m, struct ssh *ssh, int mode)
 		mac->key_len = maclen;
 	}
 	if ((r = sshbuf_get_u32(b, &comp->type)) != 0 ||
-	    (r = sshbuf_get_u32(b, (u_int *)&comp->enabled)) != 0 ||
 	    (r = sshbuf_get_cstring(b, &comp->name, NULL)) != 0)
 		goto out;
-	if (enc->name == NULL ||
-	    cipher_by_name(enc->name) != enc->cipher) {
-		r = SSH_ERR_INVALID_FORMAT;
-		goto out;
-	}
 	if (sshbuf_len(b) != 0) {
 		r = SSH_ERR_INVALID_FORMAT;
 		goto out;
@@ -2536,10 +2377,8 @@ newkeys_from_blob(struct sshbuf *m, struct ssh *ssh, int mode)
 	newkey = NULL;
 	r = 0;
  out:
-	if (newkey != NULL)
-		free(newkey);
-	if (b != NULL)
-		sshbuf_free(b);
+	free(newkey);
+	sshbuf_free(b);
 	return r;
 }
 
@@ -2550,37 +2389,30 @@ kex_from_blob(struct sshbuf *m, struct kex **kexp)
 	struct kex *kex;
 	int r;
 
-	if ((kex = calloc(1, sizeof(struct kex))) == NULL ||
-	    (kex->my = sshbuf_new()) == NULL ||
-	    (kex->peer = sshbuf_new()) == NULL) {
-		r = SSH_ERR_ALLOC_FAIL;
-		goto out;
-	}
+	if ((kex = kex_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
 	if ((r = sshbuf_get_string(m, &kex->session_id, &kex->session_id_len)) != 0 ||
 	    (r = sshbuf_get_u32(m, &kex->we_need)) != 0 ||
+	    (r = sshbuf_get_cstring(m, &kex->hostkey_alg, NULL)) != 0 ||
 	    (r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_type)) != 0 ||
+	    (r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_nid)) != 0 ||
 	    (r = sshbuf_get_u32(m, &kex->kex_type)) != 0 ||
 	    (r = sshbuf_get_stringb(m, kex->my)) != 0 ||
 	    (r = sshbuf_get_stringb(m, kex->peer)) != 0 ||
-	    (r = sshbuf_get_u32(m, &kex->flags)) != 0 ||
-	    (r = sshbuf_get_cstring(m, &kex->client_version_string, NULL)) != 0 ||
-	    (r = sshbuf_get_cstring(m, &kex->server_version_string, NULL)) != 0)
+	    (r = sshbuf_get_stringb(m, kex->client_version)) != 0 ||
+	    (r = sshbuf_get_stringb(m, kex->server_version)) != 0 ||
+	    (r = sshbuf_get_u32(m, &kex->flags)) != 0)
 		goto out;
 	kex->server = 1;
 	kex->done = 1;
 	r = 0;
  out:
 	if (r != 0 || kexp == NULL) {
-		if (kex != NULL) {
-			if (kex->my != NULL)
-				sshbuf_free(kex->my);
-			if (kex->peer != NULL)
-				sshbuf_free(kex->peer);
-			free(kex);
-		}
+		kex_free(kex);
 		if (kexp != NULL)
 			*kexp = NULL;
 	} else {
+		kex_free(*kexp);
 		*kexp = kex;
 	}
 	return r;
@@ -2594,65 +2426,35 @@ int
 ssh_packet_set_state(struct ssh *ssh, struct sshbuf *m)
 {
 	struct session_state *state = ssh->state;
-	const u_char *ssh1key, *ivin, *ivout, *keyin, *keyout, *input, *output;
-	size_t ssh1keylen, rlen, slen, ilen, olen;
+	const u_char *input, *output;
+	size_t ilen, olen;
 	int r;
-	u_int ssh1cipher = 0;
-	u_int64_t sent_bytes = 0, recv_bytes = 0;
-
-	if (!compat20) {
-		if ((r = sshbuf_get_u32(m, &state->remote_protocol_flags)) != 0 ||
-		    (r = sshbuf_get_u32(m, &ssh1cipher)) != 0 ||
-		    (r = sshbuf_get_string_direct(m, &ssh1key, &ssh1keylen)) != 0 ||
-		    (r = sshbuf_get_string_direct(m, &ivout, &slen)) != 0 ||
-		    (r = sshbuf_get_string_direct(m, &ivin, &rlen)) != 0)
-			return r;
-		if (ssh1cipher > INT_MAX)
-			return SSH_ERR_KEY_UNKNOWN_CIPHER;
-		ssh_packet_set_encryption_key(ssh, ssh1key, ssh1keylen,
-		    (int)ssh1cipher);
-		if (cipher_get_keyiv_len(&state->send_context) != (int)slen ||
-		    cipher_get_keyiv_len(&state->receive_context) != (int)rlen)
-			return SSH_ERR_INVALID_FORMAT;
-		if ((r = cipher_set_keyiv(&state->send_context, ivout)) != 0 ||
-		    (r = cipher_set_keyiv(&state->receive_context, ivin)) != 0)
-			return r;
-	} else {
-		if ((r = kex_from_blob(m, &ssh->kex)) != 0 ||
-		    (r = newkeys_from_blob(m, ssh, MODE_OUT)) != 0 ||
-		    (r = newkeys_from_blob(m, ssh, MODE_IN)) != 0 ||
-		    (r = sshbuf_get_u32(m, &state->rekey_limit)) != 0 ||
-		    (r = sshbuf_get_u32(m, &state->rekey_interval)) != 0 ||
-		    (r = sshbuf_get_u32(m, &state->p_send.seqnr)) != 0 ||
-		    (r = sshbuf_get_u64(m, &state->p_send.blocks)) != 0 ||
-		    (r = sshbuf_get_u32(m, &state->p_send.packets)) != 0 ||
-		    (r = sshbuf_get_u64(m, &state->p_send.bytes)) != 0 ||
-		    (r = sshbuf_get_u32(m, &state->p_read.seqnr)) != 0 ||
-		    (r = sshbuf_get_u64(m, &state->p_read.blocks)) != 0 ||
-		    (r = sshbuf_get_u32(m, &state->p_read.packets)) != 0 ||
-		    (r = sshbuf_get_u64(m, &state->p_read.bytes)) != 0)
-			return r;
-		/*
-		 * We set the time here so that in post-auth privsep slave we
-		 * count from the completion of the authentication.
-		 */
-		state->rekey_time = monotime();
-		/* XXX ssh_set_newkeys overrides p_read.packets? XXX */
-		if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0 ||
-		    (r = ssh_set_newkeys(ssh, MODE_OUT)) != 0)
-			return r;
-	}
-	if ((r = sshbuf_get_string_direct(m, &keyout, &slen)) != 0 ||
-	    (r = sshbuf_get_string_direct(m, &keyin, &rlen)) != 0)
+
+	if ((r = kex_from_blob(m, &ssh->kex)) != 0 ||
+	    (r = newkeys_from_blob(m, ssh, MODE_OUT)) != 0 ||
+	    (r = newkeys_from_blob(m, ssh, MODE_IN)) != 0 ||
+	    (r = sshbuf_get_u64(m, &state->rekey_limit)) != 0 ||
+	    (r = sshbuf_get_u32(m, &state->rekey_interval)) != 0 ||
+	    (r = sshbuf_get_u32(m, &state->p_send.seqnr)) != 0 ||
+	    (r = sshbuf_get_u64(m, &state->p_send.blocks)) != 0 ||
+	    (r = sshbuf_get_u32(m, &state->p_send.packets)) != 0 ||
+	    (r = sshbuf_get_u64(m, &state->p_send.bytes)) != 0 ||
+	    (r = sshbuf_get_u32(m, &state->p_read.seqnr)) != 0 ||
+	    (r = sshbuf_get_u64(m, &state->p_read.blocks)) != 0 ||
+	    (r = sshbuf_get_u32(m, &state->p_read.packets)) != 0 ||
+	    (r = sshbuf_get_u64(m, &state->p_read.bytes)) != 0)
+		return r;
+	/*
+	 * We set the time here so that in post-auth privsep slave we
+	 * count from the completion of the authentication.
+	 */
+	state->rekey_time = monotime();
+	/* XXX ssh_set_newkeys overrides p_read.packets? XXX */
+	if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0 ||
+	    (r = ssh_set_newkeys(ssh, MODE_OUT)) != 0)
 		return r;
-	if (cipher_get_keycontext(&state->send_context, NULL) != (int)slen ||
-	    cipher_get_keycontext(&state->receive_context, NULL) != (int)rlen)
-		return SSH_ERR_INVALID_FORMAT;
-	cipher_set_keycontext(&state->send_context, keyout);
-	cipher_set_keycontext(&state->receive_context, keyin);
 
-	if ((r = ssh_packet_set_compress_state(ssh, m)) != 0 ||
-	    (r = ssh_packet_set_postauth(ssh)) != 0)
+	if ((r = ssh_packet_set_postauth(ssh)) != 0)
 		return r;
 
 	sshbuf_reset(state->input);
@@ -2663,12 +2465,6 @@ ssh_packet_set_state(struct ssh *ssh, struct sshbuf *m)
 	    (r = sshbuf_put(state->output, output, olen)) != 0)
 		return r;
 
-	if (compat20) {
-		if ((r = sshbuf_get_u64(m, &sent_bytes)) != 0 ||
-		    (r = sshbuf_get_u64(m, &recv_bytes)) != 0)
-			return r;
-		roam_set_bytes(sent_bytes, recv_bytes);
-	}
 	if (sshbuf_len(m))
 		return SSH_ERR_INVALID_FORMAT;
 	debug3("%s: done", __func__);
@@ -2727,23 +2523,22 @@ sshpkt_put_stringb(struct ssh *ssh, const struct sshbuf *v)
 	return sshbuf_put_stringb(ssh->state->outgoing_packet, v);
 }
 
-#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
 int
-sshpkt_put_ec(struct ssh *ssh, const EC_POINT *v, const EC_GROUP *g)
+sshpkt_getb_froms(struct ssh *ssh, struct sshbuf **valp)
 {
-	return sshbuf_put_ec(ssh->state->outgoing_packet, v, g);
+	return sshbuf_froms(ssh->state->incoming_packet, valp);
 }
-#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */
 
-#ifdef WITH_SSH1
+#ifdef WITH_OPENSSL
+#ifdef OPENSSL_HAS_ECC
 int
-sshpkt_put_bignum1(struct ssh *ssh, const BIGNUM *v)
+sshpkt_put_ec(struct ssh *ssh, const EC_POINT *v, const EC_GROUP *g)
 {
-	return sshbuf_put_bignum1(ssh->state->outgoing_packet, v);
+	return sshbuf_put_ec(ssh->state->outgoing_packet, v, g);
 }
-#endif /* WITH_SSH1 */
+#endif /* OPENSSL_HAS_ECC */
+
 
-#ifdef WITH_OPENSSL
 int
 sshpkt_put_bignum2(struct ssh *ssh, const BIGNUM *v)
 {
@@ -2790,32 +2585,30 @@ sshpkt_get_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp)
 }
 
 int
-sshpkt_get_cstring(struct ssh *ssh, char **valp, size_t *lenp)
+sshpkt_peek_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp)
 {
-	return sshbuf_get_cstring(ssh->state->incoming_packet, valp, lenp);
+	return sshbuf_peek_string_direct(ssh->state->incoming_packet, valp, lenp);
 }
 
-#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
 int
-sshpkt_get_ec(struct ssh *ssh, EC_POINT *v, const EC_GROUP *g)
+sshpkt_get_cstring(struct ssh *ssh, char **valp, size_t *lenp)
 {
-	return sshbuf_get_ec(ssh->state->incoming_packet, v, g);
+	return sshbuf_get_cstring(ssh->state->incoming_packet, valp, lenp);
 }
-#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */
 
-#ifdef WITH_SSH1
+#ifdef WITH_OPENSSL
+#ifdef OPENSSL_HAS_ECC
 int
-sshpkt_get_bignum1(struct ssh *ssh, BIGNUM *v)
+sshpkt_get_ec(struct ssh *ssh, EC_POINT *v, const EC_GROUP *g)
 {
-	return sshbuf_get_bignum1(ssh->state->incoming_packet, v);
+	return sshbuf_get_ec(ssh->state->incoming_packet, v, g);
 }
-#endif /* WITH_SSH1 */
+#endif /* OPENSSL_HAS_ECC */
 
-#ifdef WITH_OPENSSL
 int
-sshpkt_get_bignum2(struct ssh *ssh, BIGNUM *v)
+sshpkt_get_bignum2(struct ssh *ssh, BIGNUM **valp)
 {
-	return sshbuf_get_bignum2(ssh->state->incoming_packet, v);
+	return sshbuf_get_bignum2(ssh->state->incoming_packet, valp);
 }
 #endif /* WITH_OPENSSL */
 
@@ -2840,15 +2633,74 @@ sshpkt_ptr(struct ssh *ssh, size_t *lenp)
 int
 sshpkt_start(struct ssh *ssh, u_char type)
 {
-	u_char buf[9];
-	int len;
+	u_char buf[6]; /* u32 packet length, u8 pad len, u8 type */
 
 	DBG(debug("packet_start[%d]", type));
-	len = compat20 ? 6 : 9;
-	memset(buf, 0, len - 1);
-	buf[len - 1] = type;
+	memset(buf, 0, sizeof(buf));
+	buf[sizeof(buf) - 1] = type;
 	sshbuf_reset(ssh->state->outgoing_packet);
-	return sshbuf_put(ssh->state->outgoing_packet, buf, len);
+	return sshbuf_put(ssh->state->outgoing_packet, buf, sizeof(buf));
+}
+
+static int
+ssh_packet_send_mux(struct ssh *ssh)
+{
+	struct session_state *state = ssh->state;
+	u_char type, *cp;
+	size_t len;
+	int r;
+
+	if (ssh->kex)
+		return SSH_ERR_INTERNAL_ERROR;
+	len = sshbuf_len(state->outgoing_packet);
+	if (len < 6)
+		return SSH_ERR_INTERNAL_ERROR;
+	cp = sshbuf_mutable_ptr(state->outgoing_packet);
+	type = cp[5];
+	if (ssh_packet_log_type(type))
+		debug3("%s: type %u", __func__, type);
+	/* drop everything, but the connection protocol */
+	if (type >= SSH2_MSG_CONNECTION_MIN &&
+	    type <= SSH2_MSG_CONNECTION_MAX) {
+		POKE_U32(cp, len - 4);
+		if ((r = sshbuf_putb(state->output,
+		    state->outgoing_packet)) != 0)
+			return r;
+		/* sshbuf_dump(state->output, stderr); */
+	}
+	sshbuf_reset(state->outgoing_packet);
+	return 0;
+}
+
+/*
+ * 9.2.  Ignored Data Message
+ *
+ *   byte      SSH_MSG_IGNORE
+ *   string    data
+ *
+ * All implementations MUST understand (and ignore) this message at any
+ * time (after receiving the protocol version). No implementation is
+ * required to send them. This message can be used as an additional
+ * protection measure against advanced traffic analysis techniques.
+ */
+int
+sshpkt_msg_ignore(struct ssh *ssh, u_int nbytes)
+{
+	u_int32_t rnd = 0;
+	int r;
+	u_int i;
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, nbytes)) != 0)
+		return r;
+	for (i = 0; i < nbytes; i++) {
+		if (i % 4 == 0)
+			rnd = arc4random();
+		if ((r = sshpkt_put_u8(ssh, (u_char)rnd & 0xff)) != 0)
+			return r;
+		rnd >>= 8;
+	}
+	return 0;
 }
 
 /* send it */
@@ -2856,10 +2708,9 @@ sshpkt_start(struct ssh *ssh, u_char type)
 int
 sshpkt_send(struct ssh *ssh)
 {
-	if (compat20)
-		return ssh_packet_send2(ssh);
-	else
-		return ssh_packet_send1(ssh);
+	if (ssh->state && ssh->state->mux)
+		return ssh_packet_send_mux(ssh);
+	return ssh_packet_send2(ssh);
 }
 
 int
@@ -2873,19 +2724,12 @@ sshpkt_disconnect(struct ssh *ssh, const char *fmt,...)
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 
-	if (compat20) {
-		if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
-		    (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_PROTOCOL_ERROR)) != 0 ||
-		    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
-		    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
-		    (r = sshpkt_send(ssh)) != 0)
-			return r;
-	} else {
-		if ((r = sshpkt_start(ssh, SSH_MSG_DISCONNECT)) != 0 ||
-		    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
-		    (r = sshpkt_send(ssh)) != 0)
-			return r;
-	}
+	if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_PROTOCOL_ERROR)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		return r;
 	return 0;
 }