1 files changed, 180 insertions, 0 deletions
diff --git a/src/process-packet.c b/src/process-packet.c
new file mode 100644
index 0000000..9454160
--- /dev/null
+++ b/src/process-packet.c
@@ -0,0 +1,180 @@
+/*
+ * Dropbear - a SSH2 server
+ * 
+ * Copyright (c) 2002-2004 Matt Johnston
+ * All rights reserved.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE. */
+
+#include "includes.h"
+#include "packet.h"
+#include "session.h"
+#include "dbutil.h"
+#include "ssh.h"
+#include "algo.h"
+#include "buffer.h"
+#include "kex.h"
+#include "dbrandom.h"
+#include "service.h"
+#include "auth.h"
+#include "channel.h"
+
+#define MAX_UNAUTH_PACKET_TYPE SSH_MSG_USERAUTH_PK_OK
+
+static void recv_unimplemented(void);
+
+/* process a decrypted packet, call the appropriate handler */
+void process_packet() {
+
+	unsigned char type;
+	unsigned int i;
+	time_t now;
+
+	TRACE2(("enter process_packet"))
+
+	type = buf_getbyte(ses.payload);
+	TRACE(("process_packet: packet type = %d,  len %d", type, ses.payload->len))
+
+	now = monotonic_now();
+	ses.last_packet_time_keepalive_recv = now;
+
+	/* These packets we can receive at any time */
+	switch(type) {
+
+		case SSH_MSG_IGNORE:
+			goto out;
+		case SSH_MSG_DEBUG:
+			goto out;
+
+		case SSH_MSG_UNIMPLEMENTED:
+			/* debugging XXX */
+			TRACE(("SSH_MSG_UNIMPLEMENTED"))
+			goto out;
+			
+		case SSH_MSG_DISCONNECT:
+			/* TODO cleanup? */
+			dropbear_close("Disconnect received");
+	}
+
+	/* Ignore these packet types so that keepalives don't interfere with
+	idle detection. This is slightly incorrect since a tcp forwarded
+	global request with failure won't trigger the idle timeout,
+	but that's probably acceptable */
+	if (!(type == SSH_MSG_GLOBAL_REQUEST 
+		|| type == SSH_MSG_REQUEST_FAILURE
+		|| type == SSH_MSG_CHANNEL_FAILURE)) {
+		ses.last_packet_time_idle = now;
+	}
+
+	/* This applies for KEX, where the spec says the next packet MUST be
+	 * NEWKEYS */
+	if (ses.requirenext != 0) {
+		if (ses.requirenext == type)
+		{
+			/* Got what we expected */
+			TRACE(("got expected packet %d during kexinit", type))
+		}
+		else
+		{
+			/* RFC4253 7.1 - various messages are allowed at this point.
+			The only ones we know about have already been handled though,
+			so just return "unimplemented" */
+			if (type >= 1 && type <= 49
+				&& type != SSH_MSG_SERVICE_REQUEST
+				&& type != SSH_MSG_SERVICE_ACCEPT
+				&& type != SSH_MSG_KEXINIT)
+			{
+				TRACE(("unknown allowed packet during kexinit"))
+				recv_unimplemented();
+				goto out;
+			}
+			else
+			{
+				TRACE(("disallowed packet during kexinit"))
+				dropbear_exit("Unexpected packet type %d, expected %d", type,
+						ses.requirenext);
+			}
+		}
+	}
+
+	/* Check if we should ignore this packet. Used currently only for
+	 * KEX code, with first_kex_packet_follows */
+	if (ses.ignorenext) {
+		TRACE(("Ignoring packet, type = %d", type))
+		ses.ignorenext = 0;
+		goto out;
+	}
+
+	/* Only clear the flag after we have checked ignorenext */
+	if (ses.requirenext != 0 && ses.requirenext == type)
+	{
+		ses.requirenext = 0;
+	}
+
+
+	/* Kindly the protocol authors gave all the preauth packets type values
+	 * less-than-or-equal-to 60 ( == MAX_UNAUTH_PACKET_TYPE ).
+	 * NOTE: if the protocol changes and new types are added, revisit this 
+	 * assumption */
+	if ( !ses.authstate.authdone && type > MAX_UNAUTH_PACKET_TYPE ) {
+		dropbear_exit("Received message %d before userauth", type);
+	}
+
+	for (i = 0; ; i++) {
+		if (ses.packettypes[i].type == 0) {
+			/* end of list */
+			break;
+		}
+
+		if (ses.packettypes[i].type == type) {
+			ses.packettypes[i].handler();
+			goto out;
+		}
+	}
+
+	
+	/* TODO do something more here? */
+	TRACE(("preauth unknown packet"))
+	recv_unimplemented();
+
+out:
+	ses.lastpacket = type;
+	buf_free(ses.payload);
+	ses.payload = NULL;
+
+	TRACE2(("leave process_packet"))
+}
+
+
+
+/* This must be called directly after receiving the unimplemented packet.
+ * Isn't the most clean implementation, it relies on packet processing
+ * occurring directly after decryption (direct use of ses.recvseq).
+ * This is reasonably valid, since there is only a single decryption buffer */
+static void recv_unimplemented() {
+
+	CHECKCLEARTOWRITE();
+
+	buf_putbyte(ses.writepayload, SSH_MSG_UNIMPLEMENTED);
+	/* the decryption routine increments the sequence number, we must
+	 * decrement */
+	buf_putint(ses.writepayload, ses.recvseq - 1);
+
+	encrypt_packet();
+}