sdp: gstmikey: gst_mikey_message_to_caps: extract salt and append to srtp-key

A KEMAC can hold both key and salt, so if salt is present, we should extract it
and append it to the srtp-key cap because libsrtp expects the srtp-key to hold
the concantenated srtp master key and salt.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3818>

diff --git a/subprojects/gst-plugins-base/gst-libs/gst/sdp/gstmikey.c b/subprojects/gst-plugins-base/gst-libs/gst/sdp/gstmikey.c
index 00a2b68..d875472 100644 (file)
--- a/subprojects/gst-plugins-base/gst-libs/gst/sdp/gstmikey.c
+++ b/subprojects/gst-plugins-base/gst-libs/gst/sdp/gstmikey.c
@@ -2487,7 +2487,7 @@ gst_mikey_message_to_caps (const GstMIKEYMessage * msg, GstCaps * caps)
     GstMIKEYPayloadKEMAC *p = (GstMIKEYPayloadKEMAC *) payload;
     const GstMIKEYPayload *sub;
     GstMIKEYPayloadKeyData *pkd;
-    GstBuffer *buf;
+    GstBuffer *buf, *saltbuf;
 
     if (p->enc_alg != GST_MIKEY_ENC_NULL || p->mac_alg != GST_MIKEY_MAC_NULL)
       goto done;
@@ -2500,6 +2500,11 @@ gst_mikey_message_to_caps (const GstMIKEYMessage * msg, GstCaps * caps)
 
     pkd = (GstMIKEYPayloadKeyData *) sub;
     buf = gst_buffer_new_memdup (pkd->key_data, pkd->key_len);
+    if (pkd->salt_len) {
+      saltbuf = gst_buffer_new_memdup (pkd->salt_data, pkd->salt_len);
+      gst_buffer_append (buf, saltbuf);
+      gst_buffer_unref (saltbuf);
+    }
     gst_caps_set_simple (caps, "srtp-key", GST_TYPE_BUFFER, buf, NULL);
     gst_buffer_unref (buf);