Set DSCP 41 on stream data packets. WMM capable WLAN accesspoints

should understand this and give precedence. For Internet streaming
it could be used by traffic shapers. Suggested by ollo@vdrportal (#237).
Modified Files:
	server/connectionHTTP.c server/connectionVTP.c tools/socket.c
	tools/socket.h

tools/socket.c

@@ -6,6 +6,15 @@
 #include <errno.h>
 #include <fcntl.h>
 
+// default class: best effort
+#define DSCP_BE    0
+// gold class (video): assured forwarding 4 with lowest drop precedence
+#define DSCP_AF41 34 << 2
+// premium class (voip): expedited forwarding
+#define DSCP_EF   46 << 2
+// actual DSCP value used
+#define STREAMDEV_DSCP DSCP_AF41
+
 cTBSocket::cTBSocket(int Type) {
 	memset(&m_LocalAddr, 0, sizeof(m_LocalAddr));
 	memset(&m_RemoteAddr, 0, sizeof(m_RemoteAddr));
@@ -141,3 +150,8 @@ bool cTBSocket::Shutdown(int how) {
 
 	return ::shutdown(*this, how) != -1;
 }
+
+bool cTBSocket::SetDSCP(void) {
+	int dscp = STREAMDEV_DSCP;
+	return ::setsockopt(*this, SOL_IP, IP_TOS, &dscp, sizeof(dscp)) != -1;
+}

tools/socket.h

@@ -68,6 +68,9 @@ public:
 	   an appropriate value. */
 	virtual bool Accept(const cTBSocket &Listener);
 
+	/* Sets DSCP sockopt */
+	bool SetDSCP(void);
+
 	/* LocalPort() returns the port number this socket is connected to locally.
 	   The result is undefined for a non-open socket. */
 	int LocalPort(void) const { return ntohs(m_LocalAddr.sin_port); }