From e012e752f4f1a2b06dfab4640bbbea8f084999ff Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@tinc-vpn.org>
Date: Sun, 24 May 2009 19:31:31 +0200
Subject: [PATCH] Fix initialisation of packet decryption context broken by
 commit 3308d13e7e3bf20cfeaf6f2ab17228a9820cea66.

Instead of a single, global decryption context, each node has its own context.
However, in send_ans_key(), the global context was initialised. This commit
fixes that and removes the global context completely.

Also only set status.validkey after all checks have been evaluated.
---
 src/net.h          |  1 -
 src/net_packet.c   |  1 -
 src/net_setup.c    |  2 --
 src/protocol_key.c | 44 +++++++++++++++++++++++---------------------
 4 files changed, 23 insertions(+), 25 deletions(-)

diff --git a/src/net.h b/src/net.h
index ef21179..0f70a4b 100644
--- a/src/net.h
+++ b/src/net.h
@@ -116,7 +116,6 @@ extern bool do_prune;
 extern bool do_purge;
 extern char *myport;
 extern time_t now;
-extern EVP_CIPHER_CTX packet_ctx;
 
 /* Yes, very strange placement indeed, but otherwise the typedefs get all tangled up */
 #include "connection.h"
diff --git a/src/net_packet.c b/src/net_packet.c
index a5fede1..0126d41 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -54,7 +54,6 @@
 
 int keylifetime = 0;
 int keyexpires = 0;
-EVP_CIPHER_CTX packet_ctx;
 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
 
 static void send_udppacket(node_t *, vpn_packet_t *);
diff --git a/src/net_setup.c b/src/net_setup.c
index f41f952..94e25b6 100644
--- a/src/net_setup.c
+++ b/src/net_setup.c
@@ -588,8 +588,6 @@ void close_network_connections(void)
 
 	if(myport) free(myport);
 
-	EVP_CIPHER_CTX_cleanup(&packet_ctx);
-
 	for(i = 0; i < 4; i++)
 		free(envp[i]);
 
diff --git a/src/protocol_key.c b/src/protocol_key.c
index 5baa5f4..d9719ca 100644
--- a/src/protocol_key.c
+++ b/src/protocol_key.c
@@ -127,9 +127,6 @@ bool req_key_h(connection_t *c)
 	/* Check if this key request is for us */
 
 	if(to == myself) {			/* Yes, send our own key back */
-		mykeyused = true;
-		from->received_seqno = 0;
-		memset(from->late, 0, sizeof(from->late));
 		send_ans_key(from);
 	} else {
 		if(tunnelserver)
@@ -153,18 +150,26 @@ bool send_ans_key(node_t *to)
 
 	cp();
 
-	if(!to->inkey) {
-		to->incipher = myself->incipher;
-		to->inkeylength = myself->inkeylength;
-		to->indigest = myself->indigest;
-		to->incompression = myself->incompression;
-		to->inkey = xmalloc(to->inkeylength);
+	// Set key parameters
+	to->incipher = myself->incipher;
+	to->inkeylength = myself->inkeylength;
+	to->indigest = myself->indigest;
+	to->incompression = myself->incompression;
 
-		RAND_pseudo_bytes((unsigned char *)to->inkey, to->inkeylength);
-		if(to->incipher)
-			EVP_DecryptInit_ex(&packet_ctx, to->incipher, NULL, (unsigned char *)to->inkey, (unsigned char *)to->inkey + to->incipher->key_len);
-	}
+	// Allocate memory for key
+	to->inkey = xrealloc(to->inkey, to->inkeylength);
+
+	// Create a new key
+	RAND_pseudo_bytes((unsigned char *)to->inkey, to->inkeylength);
+	if(to->incipher)
+		EVP_DecryptInit_ex(&to->inctx, to->incipher, NULL, (unsigned char *)to->inkey, (unsigned char *)to->inkey + to->incipher->key_len);
+
+	// Reset sequence number and late packet window
+	mykeyused = true;
+	to->received_seqno = 0;
+	memset(to->late, 0, sizeof(to->late));
 
+	// Convert to hexadecimal and send
 	key = alloca(2 * to->inkeylength + 1);
 	bin2hex(to->inkey, key, to->inkeylength);
 	key[to->outkeylength * 2] = '\0';
@@ -226,19 +231,13 @@ bool ans_key_h(connection_t *c)
 	}
 
 	/* Update our copy of the origin's packet key */
-
-	if(from->outkey)
-		free(from->outkey);
+	from->outkey = xrealloc(from->outkey, strlen(key) / 2);
 
 	from->outkey = xstrdup(key);
 	from->outkeylength = strlen(key) / 2;
-	hex2bin(from->outkey, from->outkey, from->outkeylength);
-	from->outkey[from->outkeylength] = '\0';
+	hex2bin(key, from->outkey, from->outkeylength);
 
-	from->status.validkey = true;
 	from->status.waitingforkey = false;
-	from->sent_seqno = 0;
-
 	/* Check and lookup cipher and digest algorithms */
 
 	if(cipher) {
@@ -293,6 +292,9 @@ bool ans_key_h(connection_t *c)
 			return false;
 		}
 
+	from->status.validkey = true;
+	from->sent_seqno = 0;
+
 	if(from->options & OPTION_PMTU_DISCOVERY && !from->mtuprobes)
 		send_mtu_probe(from);
 
-- 
2.25.1