From ace18ff91774c6b2daf46e05157f96b75113e16f Mon Sep 17 00:00:00 2001
From: Chris Hiszpanski <chris@liburtc.org>
Date: Tue, 4 May 2021 11:51:56 -0700
Subject: Set session id in sdp answer

---
 src/sdp.c  |  7 +++----
 src/urtc.c | 27 +++++++++++++++++++++------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/src/sdp.c b/src/sdp.c
index 154088c..ef73efc 100644
--- a/src/sdp.c
+++ b/src/sdp.c
@@ -497,9 +497,8 @@ int sdp_serialize(char *dst, size_t len, const struct sdp *src) {
 
     // write originator and session identifier
     n = snprintf(dst, len,
-        "o=liburtc/0.0.0 %s %s IN IP4 127.0.0.1\n",
-        src->session_id,
-        src->session_version
+        "o=- %s 0 IN IP4 127.0.0.1\n",
+        src->session_id
     );
     if (n < 0) return -URTC_ERR_SDP_MALFORMED;
     if (n >= len) return -URTC_ERR_SDP_MALFORMED;
@@ -692,7 +691,7 @@ int sdp_serialize(char *dst, size_t len, const struct sdp *src) {
 
     // write media attribute: media id
     // TODO fix hardcoded media id
-    n = snprintf(dst, len, "a=mid:0\n");
+    n = snprintf(dst, len, "a=mid:video\n");
     if (n < 0) return -URTC_ERR_SDP_MALFORMED;
     if (n >= len) return -URTC_ERR_SDP_MALFORMED;
     dst += n;
diff --git a/src/urtc.c b/src/urtc.c
index 47c32b8..7cbf790 100644
--- a/src/urtc.c
+++ b/src/urtc.c
@@ -37,6 +37,7 @@
 #include <arpa/inet.h>                  // inet_ntoa
 #include <netinet/in.h>                 // IPPROTO_UDP
 #include <sys/socket.h>                 // socket
+#include <sys/time.h>                   // gettimeofday
 #include <sys/types.h>
 
 #include "b64.h"                        // b64_encode
@@ -427,15 +428,29 @@ int urtc_add_ice_candidate(struct peerconn *pc, const char *cand) {
 }
 
 int urtc_create_answer(struct peerconn *pc, char *answer, size_t size) {
-    char pwd[18]; // 24 base64 characters
-    char ufrag[3]; // 4 base64 characters
+    // write unique session id
+    {
+        struct timeval now;
+        if (-1 == gettimeofday(&now, NULL)) {
+            return -1;
+        }
+        snprintf(pc->ldesc.session_id, sizeof(pc->ldesc.session_id),
+                "%lu", now.tv_sec);
+    }
 
-    prng(pwd, sizeof(pwd));
-    prng(ufrag, sizeof(ufrag));
+    strcpy(pc->ldesc.mid[0], "video");
 
-    b64_encode(pc->ldesc.pwd, pwd, sizeof(pwd));
-    b64_encode(pc->ldesc.ufrag, ufrag, sizeof(ufrag));
+    // write ice-pwd and ice-ufrag
+    {
+        char pwd[18];                   // 24 base64 characters
+        char ufrag[3];                  // 4 base64 characters
+        prng(pwd, sizeof(pwd));
+        prng(ufrag, sizeof(ufrag));
+        b64_encode(pc->ldesc.pwd, pwd, sizeof(pwd));
+        b64_encode(pc->ldesc.ufrag, ufrag, sizeof(ufrag));
+    }
 
+    pc->ldesc.ice_options.trickle = true;
     pc->ldesc.mode = SDP_MODE_SEND_ONLY;
 
     return sdp_serialize(answer, size, &pc->ldesc);
-- 
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