webrtc-gcc-ns3

test google congestion control algorithm on ns3.31 The ex-webrtc module depends on libwebrtc.a

Preparation

There are three ways to get libwebtc.a

The first approach

Download offcial webrtc. This approch is not suggested. ex-webrtc is referred the code under /webrtc/test/scenario. It is small discrete event simulator and only suports to build two nodes topology (webrtc/test/scenario/network_node.cc). I copy some source files in test and api under ex-webrtc. Once these files are changed by webrtc, building error will encountered.
1 download webrtc.

mkdir webrtc-checkout  
cd webrtc-checkout  
fetch --nohooks webrtc  
gclient sync  
cd src   
git checkout -b m84 refs/remotes/branch-heads/4147   
gclient sync  

2 Add a flag in basic_types.h (third_party/libyuv/include/libyuv):

#define LIBYUV_LEGACY_TYPES  

3 Add two files to rtc_base library(BUILD.gn):

rtc_library("rtc_base") {
  sources = [
    ...
    "memory_stream.cc",
    "memory_stream.h",
    "memory_usage.cc",
    "memory_usage.h",
    ....
    ]
}

Remove them out of the original library(rtc_library("rtc_base_tests_utils")).
The build flag rtc_include_tests is diabled, or else there will be errors when compiling.
4 Delete code in webrtc:

//third_party/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc   
bool ModuleRtpRtcpImpl::TrySendPacket(RtpPacketToSend* packet,  
                                      const PacedPacketInfo& pacing_info) {  
  RTC_DCHECK(rtp_sender_);  
  //if (!rtp_sender_->packet_generator.SendingMedia()) {   
 //   return false;  
 // }  
  rtp_sender_->packet_sender.SendPacket(packet, pacing_info);  
  return true;  
}

5 Add code in webrtc(to get send bandwidth):

//third_party/webrtc/call/call.h  
class Call {  
    virtual uint32_t last_bandwidth_bps(){return 0;}  
};  
//third_party/webrtc/call/call.cc  
namespace internal {  
class Call{
    uint32_t last_bandwidth_bps() override {return last_bandwidth_bps_;}  
}
}  

6 Built webrtc with clang. Get clang installed first.

• first step:

cd webrtc/src  
gn gen out/m84 --args='is_debug=false is_component_build=false is_clang=true rtc_include_tests=false rtc_use_h264=true rtc_enable_protobuf=false use_rtti=true use_custom_libcxx=false treat_warnings_as_errors=false use_ozone=true'   

• second step:

cd webrtc/src  
ninja -C out/m84  

The second approach

Download the webrtc I upload. This approach to build libwertc.a is suggested for these intending to make some change in webrtc source code.
url: https://pan.baidu.com/s/18F26BAmZhj_CAQzKNUeDSA
auth code: j4ts
After download the code, decompress it:

cat webrtc.tar.gz* |tar zx  

Built webrtc with clang (refer to step 6 above).

The third approach

Download webrtc header and libwebrtc.a directly for fast prototype.
No bother is needed to build webrtc.
url: https://pan.baidu.com/s/1WAwxKjNg67deHrubYl1jFA
auth code: h21w

Build ns3.31

1 Add environment variable

sudo gedit source /etc/profile   
export WEBRTC_SRC_DIR=/xx/xx/xx/webrtc/src   

WEBRTC_SRC_DIR is the path where you put webrtc source code.
The reason for this can be found in ex-webrtc/wscript..

webrtc_code_path = os.environ['WEBRTC_SRC_DIR']  
webrtc_lib_path = os.path.join(webrtc_code_path, 'out', 'm84', 'obj')  
webrtc_absl_path = os.path.join(webrtc_code_path, 'third_party', 'abseil-cpp')  

2 Enable c++14 build flag (ns-allinone-3.31/ns-3.31/wscript).

opt.add_option('--cxx-standard',
               help=('Compile NS-3 with the given C++ standard'),
               type='string', default='-std=c++14', dest='cxx_standard')  

3 Change the warning flags in ns3 (ns-allinone-3.31/ns-3.31/waf-tools/cflags.h).

self.warnings_flags = [['-Wall'], ['-Wno-unused-parameter'], ['-Wextra']]

The origin content can be seen here.
4 Put the folder ex-webrtc under ns-allinone-3.31/ns-3.31/src.
5 Build ns3 with clang++

cd ns-allinone-3.31/ns-3.31  
source /etc/profile  
CXX="clang++" ./waf configure  
./waf build  

Run example:

1 Put the file webrtc-static.cc under ns-allinone-3.31/ns-3.31/scratch/.
2 Rebuild ns3

cd ns-allinone-3.31/ns-3.31  
source /etc/profile  
CXX="clang++" ./waf configure  
./waf build  

3 Create a folder named traces under ns-allinone-3.31/ns-3.31/. The traced data can be found there.
4 Run the example in simulation mode (ns3 event time):

./waf run "scratch/webrtc-static --m=simu"  

5 Run the example in emulation mode (real clock):

./waf run "scratch/webrtc-static --m=emu"  

The code here is used by gym to build reinforce learning based congestion controller.

Results:

In simulation mode:

In Emulation mode:

The difference is clear.

Reference:

[1] build webrtc with gcc
[2] the blog in chinese to configure this code on ns3
[3] gym-Build reinforce learning congestion control controller for webrtc