Add support for automatic DH ephemeral keys.

This allows an SSL server to enable DHE ciphers with a single setting,
which results in an DH key being generated based on the server key length.

Partly based on OpenSSL.

1 files changed, 17 insertions, 4 deletions

diff --git a/src/lib/libssl/s3_srvr.c b/src/lib/libssl/s3_srvr.c
index 1b97895f76..3a311fbfb6 100644
--- a/src/lib/libssl/s3_srvr.c
+++ b/src/lib/libssl/s3_srvr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s3_srvr.c,v 1.88 2014/10/31 14:51:01 jsing Exp $ */
+/* $OpenBSD: s3_srvr.c,v 1.89 2014/10/31 15:25:55 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1360,10 +1360,21 @@ ssl3_send_server_key_exchange(SSL *s)
                 r[0] = r[1] = r[2] = r[3] = NULL;
                 n = 0;
                 if (type & SSL_kDHE) {
-                        dhp = cert->dh_tmp;
-                        if ((dhp == NULL) && (s->cert->dh_tmp_cb != NULL))
+                        if (s->cert->dh_tmp_auto != 0) {
+                                if ((dhp = ssl_get_auto_dh(s)) == NULL) {
+                                        al = SSL_AD_INTERNAL_ERROR;
+                                        SSLerr(
+                                            SSL_F_SSL3_SEND_SERVER_KEY_EXCHANGE,
+                                            ERR_R_INTERNAL_ERROR);
+                                        goto f_err;
+                                }
+                        } else
+                                dhp = cert->dh_tmp;
+
+                        if (dhp == NULL && s->cert->dh_tmp_cb != NULL)
                                 dhp = s->cert->dh_tmp_cb(s, 0,
                                     SSL_C_PKEYLENGTH(s->s3->tmp.new_cipher));
+
                         if (dhp == NULL) {
                                 al = SSL_AD_HANDSHAKE_FAILURE;
                                 SSLerr(SSL_F_SSL3_SEND_SERVER_KEY_EXCHANGE,
@@ -1377,7 +1388,9 @@ ssl3_send_server_key_exchange(SSL *s)
                                 goto err;
                         }
 
-                        if ((dh = DHparams_dup(dhp)) == NULL) {
+                        if (s->cert->dh_tmp_auto != 0) {
+                                dh = dhp;
+                        } else if ((dh = DHparams_dup(dhp)) == NULL) {
                                 SSLerr(SSL_F_SSL3_SEND_SERVER_KEY_EXCHANGE,
                                     ERR_R_DH_LIB);
                                 goto err;