- markus@cvs.openbsd.org 2002/03/26 23:14:51
[kex.c]
generate a new cookie for each SSH2_MSG_KEXINIT message we send out
diff --git a/kex.c b/kex.c
index 8097ab0..194a865 100644
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
*/
#include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.48 2002/03/18 17:50:31 provos Exp $");
+RCSID("$OpenBSD: kex.c,v 1.49 2002/03/26 23:14:51 markus Exp $");
#include <openssl/crypto.h>
@@ -57,16 +57,15 @@
static void
kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
{
- u_int32_t rand = 0;
int i;
buffer_clear(b);
- for (i = 0; i < KEX_COOKIE_LEN; i++) {
- if (i % 4 == 0)
- rand = arc4random();
- buffer_put_char(b, rand & 0xff);
- rand >>= 8;
- }
+ /*
+ * add a dummy cookie, the cookie will be overwritten by
+ * kex_send_kexinit(), each time a kexinit is set
+ */
+ for (i = 0; i < KEX_COOKIE_LEN; i++)
+ buffer_put_char(b, 0);
for (i = 0; i < PROPOSAL_MAX; i++)
buffer_put_cstring(b, proposal[i]);
buffer_put_char(b, 0); /* first_kex_packet_follows */
@@ -152,6 +151,10 @@
void
kex_send_kexinit(Kex *kex)
{
+ u_int32_t rand = 0;
+ u_char *cookie;
+ int i;
+
if (kex == NULL) {
error("kex_send_kexinit: no kex, cannot rekey");
return;
@@ -161,6 +164,17 @@
return;
}
kex->done = 0;
+
+ /* generate a random cookie */
+ if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
+ fatal("kex_send_kexinit: kex proposal too short");
+ cookie = buffer_ptr(&kex->my);
+ for (i = 0; i < KEX_COOKIE_LEN; i++) {
+ if (i % 4 == 0)
+ rand = arc4random();
+ cookie[i] = rand;
+ rand >>= 8;
+ }
packet_start(SSH2_MSG_KEXINIT);
packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
packet_send();