mikey: allow passing srtp or srtcp to create mikey message

Current implementation requires all srtp and srtcp parameters to be
given in the caps. MIKEY uses only one algorithm for encryption and one
for authentication so we now allow passing srtp or srtcp parameters. If
both are given srtp parametres will be preferred.

https://bugzilla.gnome.org/show_bug.cgi?id=765027

diff --git a/gst-libs/gst/sdp/gstmikey.c b/gst-libs/gst/sdp/gstmikey.c
index 6aa3941..358aa2f 100644 (file)
--- a/gst-libs/gst/sdp/gstmikey.c
+++ b/gst-libs/gst/sdp/gstmikey.c
@@ -2204,6 +2204,7 @@ gst_mikey_message_new_from_caps (GstCaps * caps)
   GstMapInfo info;
   GstBuffer *srtpkey;
   const GValue *val;
+  const gchar *cipher, *auth;
   const gchar *srtpcipher, *srtpauth, *srtcpcipher, *srtcpauth;
 
   g_return_val_if_fail (caps != NULL && GST_IS_CAPS (caps), NULL);
@@ -2224,12 +2225,23 @@ gst_mikey_message_new_from_caps (GstCaps * caps)
   srtcpcipher = gst_structure_get_string (s, "srtcp-cipher");
   srtcpauth = gst_structure_get_string (s, "srtcp-auth");
 
-  if (srtpcipher == NULL || srtpauth == NULL || srtcpcipher == NULL ||
-      srtcpauth == NULL) {
+  /* we need srtp cipher/auth or srtcp cipher/auth */
+  if ((srtpcipher == NULL || srtpauth == NULL)
+      && (srtcpcipher == NULL || srtcpauth == NULL)) {
     GST_WARNING ("could not find the right SRTP parameters in caps");
     return NULL;
   }
 
+  /* prefer srtp cipher over srtcp */
+  cipher = srtpcipher;
+  if (cipher == NULL)
+    cipher = srtcpcipher;
+
+  /* prefer srtp auth over srtcp */
+  auth = srtpauth;
+  if (auth == NULL)
+    auth = srtcpauth;
+
   msg = gst_mikey_message_new ();
   /* unencrypted MIKEY message, we send this over TLS so this is allowed */
   gst_mikey_message_set_info (msg, GST_MIKEY_VERSION, GST_MIKEY_TYPE_PSK_INIT,
@@ -2248,14 +2260,14 @@ gst_mikey_message_new_from_caps (GstCaps * caps)
   byte = 1;
   gst_mikey_payload_sp_add_param (payload, GST_MIKEY_SP_SRTP_ENC_ALG, 1, &byte);
   /* encryption key length */
-  byte = enc_key_length_from_cipher_name (srtpcipher);
+  byte = enc_key_length_from_cipher_name (cipher);
   gst_mikey_payload_sp_add_param (payload, GST_MIKEY_SP_SRTP_ENC_KEY_LEN, 1,
       &byte);
   /* only HMAC-SHA1 */
   gst_mikey_payload_sp_add_param (payload, GST_MIKEY_SP_SRTP_AUTH_ALG, 1,
       &byte);
   /* authentication key length */
-  byte = auth_key_length_from_auth_name (srtpauth);
+  byte = auth_key_length_from_auth_name (auth);
   gst_mikey_payload_sp_add_param (payload, GST_MIKEY_SP_SRTP_AUTH_KEY_LEN, 1,
       &byte);
   /* we enable encryption on RTP and RTCP */