Convert ssl3_get_client_kex_dhe() to CBS and perform some general code

cleanup, including the removal of a dead code path.

ok beck@

1 files changed, 29 insertions, 38 deletions

diff --git a/src/lib/libssl/s3_srvr.c b/src/lib/libssl/s3_srvr.c
index 65625cef26..e0d16e5cf2 100644
--- a/src/lib/libssl/s3_srvr.c
+++ b/src/lib/libssl/s3_srvr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s3_srvr.c,v 1.132 2016/11/06 15:06:52 jsing Exp $ */
+/* $OpenBSD: s3_srvr.c,v 1.133 2016/11/17 15:22:41 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1742,62 +1742,53 @@ err:
 static int
 ssl3_get_client_kex_dhe(SSL *s, unsigned char *p, long n)
 {
-        BIGNUM *pub = NULL;
-        DH *dh_srvr;
-        int i, al;
+        BIGNUM *bn = NULL;
+        int key_size, al;
+        CBS cbs, dh_Yc;
+        DH *dh;
 
-        if (2 > n)
-                goto truncated;
-        n2s(p, i);
-        if (n != i + 2) {
-                SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,
-                    SSL_R_DH_PUBLIC_VALUE_LENGTH_IS_WRONG);
+        if (n < 0)
                 goto err;
-        }
 
-        if (n == 0L) {
-                /* the parameters are in the cert */
+        CBS_init(&cbs, p, n);
+
+        if (!CBS_get_u16_length_prefixed(&cbs, &dh_Yc))
+                goto truncated;
+
+        if (CBS_len(&cbs) != 0)
+                goto truncated;
+
+        if (s->s3->tmp.dh == NULL) {
                 al = SSL_AD_HANDSHAKE_FAILURE;
                 SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,
-                    SSL_R_UNABLE_TO_DECODE_DH_CERTS);
+                    SSL_R_MISSING_TMP_DH_KEY);
                 goto f_err;
-        } else {
-                if (s->s3->tmp.dh == NULL) {
-                        al = SSL_AD_HANDSHAKE_FAILURE;
-                        SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,
-                            SSL_R_MISSING_TMP_DH_KEY);
-                        goto f_err;
-                } else
-                        dh_srvr = s->s3->tmp.dh;
         }
+        dh = s->s3->tmp.dh;
 
-        pub = BN_bin2bn(p, i, NULL);
-        if (pub == NULL) {
+        if ((bn = BN_bin2bn(CBS_data(&dh_Yc), CBS_len(&dh_Yc), NULL)) == NULL) {
                 SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,
                     SSL_R_BN_LIB);
                 goto err;
         }
 
-        i = DH_compute_key(p, pub, dh_srvr);
-
-        if (i <= 0) {
-                SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,
-                    ERR_R_DH_LIB);
-                BN_clear_free(pub);
+        key_size = DH_compute_key(p, bn, dh);
+        if (key_size <= 0) {
+                SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE, ERR_R_DH_LIB);
+                BN_clear_free(bn);
                 goto err;
         }
 
-        DH_free(s->s3->tmp.dh);
-        s->s3->tmp.dh = NULL;
-
-        BN_clear_free(pub);
-        pub = NULL;
-
         s->session->master_key_length =
             s->method->ssl3_enc->generate_master_secret(
-                s, s->session->master_key, p, i);
+                s, s->session->master_key, p, key_size);
 
-        explicit_bzero(p, i);
+        explicit_bzero(p, key_size);
+
+        DH_free(s->s3->tmp.dh);
+        s->s3->tmp.dh = NULL;
+
+        BN_clear_free(bn);
 
         return (1);