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/lib/libssl/s3_srvr.c b/lib/libssl/s3_srvr.c
index 65625cef26b..e0d16e5cf2f 100644
--- a/lib/libssl/s3_srvr.c
+++ b/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);