Deduplicate some extension processing code.

ok tb@ inoguchi@

1 files changed, 47 insertions, 58 deletions

diff --git a/lib/libssl/ssl_tlsext.c b/lib/libssl/ssl_tlsext.c
index 91b74b5d3fc..f91b790f99f 100644
--- a/lib/libssl/ssl_tlsext.c
+++ b/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.49 2019/05/29 17:28:37 jsing Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.50 2019/11/15 15:14:02 beck Exp $ */
 /*
  * Copyright (c) 2016, 2017, 2019 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -1223,17 +1223,11 @@ tlsext_keyshare_client_needs(SSL *s)
 	    TLS1_3_VERSION);
 }
 
-int
-tlsext_keyshare_client_build(SSL *s, CBB *cbb)
+static int
+tlsext_keyshare_x25519_internal(SSL *s, CBB *cbb)
 {
 	uint8_t *public_key = NULL, *private_key = NULL;
-	CBB client_shares, key_exchange;
-
-	/* Generate and provide key shares. */
-	if (!CBB_add_u16_length_prefixed(cbb, &client_shares))
-		return 0;
-
-	/* XXX - other groups. */
+	CBB key_exchange;
 
 	/* Generate X25519 key pair. */
 	if ((public_key = malloc(X25519_KEY_LENGTH)) == NULL)
@@ -1243,16 +1237,13 @@ tlsext_keyshare_client_build(SSL *s, CBB *cbb)
 	X25519_keypair(public_key, private_key);
 
 	/* Add the group and serialize the public key. */
-	if (!CBB_add_u16(&client_shares, tls1_ec_nid2curve_id(NID_X25519)))
+	if (!CBB_add_u16(cbb, tls1_ec_nid2curve_id(NID_X25519)))
 		goto err;
-	if (!CBB_add_u16_length_prefixed(&client_shares, &key_exchange))
+	if (!CBB_add_u16_length_prefixed(cbb, &key_exchange))
 		goto err;
 	if (!CBB_add_bytes(&key_exchange, public_key, X25519_KEY_LENGTH))
 		goto err;
 
-	if (!CBB_flush(cbb))
-		goto err;
-
 	S3I(s)->hs_tls13.x25519_public = public_key;
 	S3I(s)->hs_tls13.x25519_private = private_key;
 
@@ -1266,6 +1257,32 @@ tlsext_keyshare_client_build(SSL *s, CBB *cbb)
 }
 
 int
+tlsext_keyshare_client_build(SSL *s, CBB *cbb)
+{
+	CBB client_shares;
+
+	/* Generate and provide key shares. */
+	if (!CBB_add_u16_length_prefixed(cbb, &client_shares))
+		return 0;
+
+	/* XXX - other groups. */
+
+	if (!tlsext_keyshare_x25519_internal(s, &client_shares))
+		return 0;
+
+	if (!CBB_flush(cbb))
+		goto err;
+
+	return 1;
+
+ err:
+	freezero(S3I(s)->hs_tls13.x25519_public, X25519_KEY_LENGTH);
+	freezero(S3I(s)->hs_tls13.x25519_private, X25519_KEY_LENGTH);
+
+	return 0;
+}
+
+int
 tlsext_keyshare_server_parse(SSL *s, CBS *cbs, int *alert)
 {
 	CBS client_shares;
@@ -1324,41 +1341,21 @@ tlsext_keyshare_server_needs(SSL *s)
 int
 tlsext_keyshare_server_build(SSL *s, CBB *cbb)
 {
-	uint8_t *public_key = NULL, *private_key = NULL;
-	CBB key_exchange;
-
-	/* XXX deduplicate with client code */
-
 	/* X25519 */
 	if (S3I(s)->hs_tls13.x25519_peer_public == NULL)
 		return 0;
 
-	/* Generate X25519 key pair. */
-	if ((public_key = malloc(X25519_KEY_LENGTH)) == NULL)
-		goto err;
-	if ((private_key = malloc(X25519_KEY_LENGTH)) == NULL)
-		goto err;
-	X25519_keypair(public_key, private_key);
-
-	/* Add the group and serialize the public key. */
-	if (!CBB_add_u16(cbb, tls1_ec_nid2curve_id(NID_X25519)))
-		goto err;
-	if (!CBB_add_u16_length_prefixed(cbb, &key_exchange))
-		goto err;
-	if (!CBB_add_bytes(&key_exchange, public_key, X25519_KEY_LENGTH))
-		goto err;
+	if (!tlsext_keyshare_x25519_internal(s, cbb))
+		return 0;
 
 	if (!CBB_flush(cbb))
 		goto err;
 
-	S3I(s)->hs_tls13.x25519_public = public_key;
-	S3I(s)->hs_tls13.x25519_private = private_key;
-
 	return 1;
 
  err:
-	freezero(public_key, X25519_KEY_LENGTH);
-	freezero(private_key, X25519_KEY_LENGTH);
+	freezero(S3I(s)->hs_tls13.x25519_public, X25519_KEY_LENGTH);
+	freezero(S3I(s)->hs_tls13.x25519_private, X25519_KEY_LENGTH);
 
 	return 0;
 }
@@ -1534,8 +1531,8 @@ tlsext_cookie_client_needs(SSL *s)
 	    S3I(s)->hs_tls13.cookie != NULL);
 }
 
-int
-tlsext_cookie_client_build(SSL *s, CBB *cbb)
+static int
+tlsext_cookie_build_internal(SSL *s, CBB *cbb)
 {
 	CBB cookie;
 
@@ -1553,6 +1550,12 @@ tlsext_cookie_client_build(SSL *s, CBB *cbb)
 }
 
 int
+tlsext_cookie_client_build(SSL *s, CBB *cbb)
+{
+	return tlsext_cookie_build_internal(s, cbb);
+}
+
+int
 tlsext_cookie_server_parse(SSL *s, CBS *cbs, int *alert)
 {
 	CBS cookie;
@@ -1599,25 +1602,11 @@ tlsext_cookie_server_needs(SSL *s)
 }
 
 int
-tlsext_cookie_server_build(SSL *s, CBB *cbb)
-{
-	CBB cookie;
-
-	/* XXX deduplicate with client code */
-
-	if (!CBB_add_u16_length_prefixed(cbb, &cookie))
-		return 0;
-
-	if (!CBB_add_bytes(&cookie, S3I(s)->hs_tls13.cookie,
-	    S3I(s)->hs_tls13.cookie_len))
-		return 0;
-
-	if (!CBB_flush(cbb))
-		return 0;
-
-	return 1;
+tlsext_cookie_server_build(SSL *s, CBB *cbb) {
+	return tlsext_cookie_build_internal(s, cbb);
 }
 
+
 int
 tlsext_cookie_client_parse(SSL *s, CBS *cbs, int *alert)
 {