1 files changed, 161 insertions, 0 deletions
diff --git a/process-packet.c b/process-packet.c
new file mode 100644
index 0000000..7b73cb7
--- /dev/null
+++ b/process-packet.c
@@ -0,0 +1,161 @@
+/*
+ * 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 "random.h"
+#include "service.h"
+#include "auth.h"
+#include "channel.h"
+
+#define MAX_UNAUTH_PACKET_TYPE SSH_MSG_USERAUTH_PK_OK
+
+static void recv_unimplemented();
+
+/* process a decrypted packet, call the appropriate handler */
+void process_packet() {
+
+	unsigned char type;
+	unsigned int i;
+
+	TRACE(("enter process_packet"));
+
+	type = buf_getbyte(ses.payload);
+	TRACE(("process_packet: packet type = %d", type));
+
+	/* These packets we can receive at any time */
+	switch(type) {
+
+		case SSH_MSG_IGNORE:
+		case SSH_MSG_DEBUG:
+			TRACE(("received SSH_MSG_IGNORE or SSH_MSG_DEBUG"));
+			goto out;
+
+		case SSH_MSG_UNIMPLEMENTED:
+			/* debugging XXX */
+			TRACE(("SSH_MSG_UNIMPLEMENTED"));
+			dropbear_exit("received SSH_MSG_UNIMPLEMENTED");
+			
+		case SSH_MSG_DISCONNECT:
+			/* TODO cleanup? */
+			dropbear_close("Disconnect received");
+	}
+
+
+	/* This applies for KEX, where the spec says the next packet MUST be
+	 * NEWKEYS */
+	if (ses.requirenext != 0) {
+		if (ses.requirenext != type) {
+			/* TODO send disconnect? */
+			dropbear_exit("unexpected packet type %d, expected %d", type,
+					ses.requirenext);
+		} else {
+			/* Got what we expected */
+			ses.requirenext = 0;
+		}
+	}
+
+	/* 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;
+	}
+
+	/* XXX This code somewhere else perhaps? */
+#ifdef DROPBEAR_CLIENT
+	if (IS_DROPBEAR_CLIENT) {
+
+		/* XXX - needs changing */
+		/* In client mode, we REUSE ses.expecting to proceed to the 
+		 *  next phase when a packet was received.
+		 * If the "expecting" flag is set to a non-null value, it will 
+		 *  be reset when a packet of that type is received.
+		 * This is different from the server-mode behaviour, when 
+		 *  a packet type mismatch would have caused sudden death.
+		 */
+		 
+		/* check that we aren't expecting a particular packet */
+		if (cli_ses.expecting && cli_ses.expecting == type) {
+			cli_ses.expecting = 0;
+		}
+	}
+#endif
+
+	/* 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.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:
+	buf_free(ses.payload);
+	ses.payload = NULL;
+
+	TRACE(("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();
+}