Fix traffic class configuration

CHANGELOG.md

@@ -41,6 +41,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Small fixes for 0.1.0 release. [#32](https://github.com/netsec-ethz/scion-java-client/pull/32)
 - Fix NPE after 2nd send() in unconnected channel + cleanup. 
   [#33](https://github.com/netsec-ethz/scion-java-client/pull/33)
+- Fixed traffic class not set. [#36](https://github.com/netsec-ethz/scion-java-client/pull/36)
 
 ### Removed
 

src/main/java/org/scion/AbstractDatagramChannel.java

@@ -529,7 +529,15 @@ protected void buildHeader(
 
       byte[] rawPath = path.getRawPath();
       ScionHeaderParser.write(
-          buffer, payloadLength, rawPath.length, srcIA, srcAddress, dstIA, dstAddress, hdrType);
+          buffer,
+          payloadLength,
+          rawPath.length,
+          srcIA,
+          srcAddress,
+          dstIA,
+          dstAddress,
+          hdrType,
+          cfgTrafficClass);
       ScionHeaderParser.writePath(buffer, rawPath);
 
       if (hdrType == InternalConstants.HdrTypes.UDP) {

src/main/java/org/scion/internal/ScionHeaderParser.java

@@ -324,15 +324,16 @@ public static void write(
       byte[] srcAddress,
       long dstIsdAs,
       byte[] dstAddress,
-      InternalConstants.HdrTypes hdrType) {
+      InternalConstants.HdrTypes hdrType,
+      int trafficClass) {
     int sl = srcAddress.length / 4 - 1;
     int dl = dstAddress.length / 4 - 1;
 
     int i0 = 0;
     int i1 = 0;
     int i2 = 0;
     i0 = writeInt(i0, 0, 4, 0); // version = 0
-    i0 = writeInt(i0, 4, 8, 0); // TrafficClass = 0
+    i0 = writeInt(i0, 4, 8, trafficClass); // TrafficClass = 0
     i0 = writeInt(i0, 12, 20, 1); // FlowID = 1
     data.putInt(i0);
     i1 = writeInt(i1, 0, 8, hdrType.code); // NextHdr = 17 is for UDP OverlayHeader

src/test/java/org/scion/api/DatagramChannelApiTest.java

@@ -644,7 +644,7 @@ void setOption_TrafficClass() throws IOException {
       mock.setSendCallback(
           (buffer, address) -> {
             assertEquals(
-                0, ScionPacketInspector.readPacket(buffer).getScionHeader().getTrafficClass());
+                42, ScionPacketInspector.readPacket(buffer).getScionHeader().getTrafficClass());
             return 0;
           });
       channel.send(buf, dummyAddress);

src/test/java/org/scion/internal/HeaderComposeTest.java

@@ -92,7 +92,8 @@ void testCompose() throws IOException {
         srcAddress,
         dstIA,
         dstAddress,
-        InternalConstants.HdrTypes.UDP);
+        InternalConstants.HdrTypes.UDP,
+        0);
     ScionHeaderParser.writePath(p, path);
 
     // Overlay header