From 81966f2c4858014a37344555babfe9a1da13b202 Mon Sep 17 00:00:00 2001
From: Dw9 <xweimvp@gmail.com>
Date: Tue, 29 Aug 2023 11:22:30 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=E6=9C=AA=E5=BC=80=E5=90=AFsc?=
 =?UTF-8?q?tp=E6=97=B6=EF=BC=8Cwebrtc=20datachannel=20sdp=E4=BA=A4?=
 =?UTF-8?q?=E6=8D=A2=E7=9B=B8=E5=85=B3bug=20(#2791)?=
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主要优化如下：
1、通过设置port为0 声明不支持datachannel(而不是inactive)。
2、设置正确的ice用户名和密码，防止ice建联失败。
3、group attribute移除datachannel的mid。
3、datachannel 相关sdp移除rtcp相关描述。
---
 webrtc/Sdp.cpp             | 13 ++++++++-----
 webrtc/WebRtcTransport.cpp |  6 ++++--
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/webrtc/Sdp.cpp b/webrtc/Sdp.cpp
index 7b2e06e9..7051e42f 100644
--- a/webrtc/Sdp.cpp
+++ b/webrtc/Sdp.cpp
@@ -1555,7 +1555,10 @@ shared_ptr<RtcSession> RtcConfigure::createAnswer(const RtcSession &offer) const
     //设置音视频端口复用
     if (!offer.group.mids.empty()) {
         for (auto &m : ret->media) {
-            ret->group.mids.emplace_back(m.mid);
+            //The remote end has rejected (port 0) the m-section, so it should not be putting its mid in the group attribute.
+            if (m.port) {
+                ret->group.mids.emplace_back(m.mid);
+            }
         }
     }
     return ret;
@@ -1613,15 +1616,15 @@ RETRY:
     if (offer_media.type == TrackApplication) {
         RtcMedia answer_media = offer_media;
         answer_media.role = mathDtlsRole(offer_media.role);
-#ifdef ENABLE_SCTP
-        answer_media.direction = matchDirection(offer_media.direction, configure.direction);
-        answer_media.candidate = configure.candidate;
         answer_media.ice_ufrag = configure.ice_ufrag;
         answer_media.ice_pwd = configure.ice_pwd;
         answer_media.fingerprint = configure.fingerprint;
         answer_media.ice_lite = configure.ice_lite;
+#ifdef ENABLE_SCTP
+        answer_media.candidate = configure.candidate;
 #else
-        answer_media.direction = RtpDirection::inactive;
+        answer_media.port = 0;
+        WarnL << "answer sdp忽略application mline, 请安装usrsctp后再测试datachannel功能";
 #endif
         ret->media.emplace_back(answer_media);
         return;
diff --git a/webrtc/WebRtcTransport.cpp b/webrtc/WebRtcTransport.cpp
index 127a1987..1200c148 100644
--- a/webrtc/WebRtcTransport.cpp
+++ b/webrtc/WebRtcTransport.cpp
@@ -564,8 +564,10 @@ void WebRtcTransportImp::onCheckAnswer(RtcSession &sdp) {
 
         GET_CONFIG(uint16_t, udp_port, Rtc::kPort);
         GET_CONFIG(uint16_t, tcp_port, Rtc::kTcpPort);
-        m.rtcp_addr.port = udp_port ? udp_port : tcp_port;
-        m.port = m.rtcp_addr.port;
+        m.port = m.port ? (udp_port ? udp_port : tcp_port) : 0;
+        if (m.type != TrackApplication) {
+            m.rtcp_addr.port = m.port;
+        }
         sdp.origin.address = m.addr.address;
     }