res_rtp_asterisk: Issue ERROR if res_srtp is not found.

While trying to get WebRTC working with chan_pjsip, I was running
into the following error:

    Attempted to set an invalid DTLS-SRTP configuration on RTP
    instance...

Josh helpfully pointed out that res_srtp.so might not be loaded, and
sure enough, it wasn't. This patch adds a ERROR indiciating as much
to hopefully help others having a similar problem.

Change-Id: I13aa477b47b299876728a21b130998a0ea6cd19f

diff --git a/res/res_rtp_asterisk.c b/res/res_rtp_asterisk.c
index 6df8a6e17cf76848b16420e759ac705c7fbc3a19..ed7dde01d8c9cce14bcd0112dcf9c208dab23e77 100644 (file)
--- a/res/res_rtp_asterisk.c
+++ b/res/res_rtp_asterisk.c
@@ -1270,6 +1270,7 @@ static int ast_rtp_dtls_set_configuration(struct ast_rtp_instance *instance, con
        }
 
        if (!ast_rtp_engine_srtp_is_registered()) {
+               ast_log(LOG_ERROR, "SRTP support module is not loaded or available. Try loading res_srtp.so.\n");
                return -1;
        }