- feature: DSCP value for RTP packets defineable (by Nick

Vermeer, Internet Express)

ChangeLog

@@ -1,5 +1,7 @@
 0.5.11
 ======
+  19-Apr-2005:  - feature: DSCP value for RTP packets defineable (by Nick
+                  Vermeer, Internet Express)
   15-Apr-2005:  - feature: auto-save registration table during operation
   10-Apr-2005:  - started DocBook documentation
    3-Apr-2005:  - fix: changing public IP address

doc/siproxd.conf.example

@@ -126,6 +126,22 @@ rtp_port_high = 7079
 #
 rtp_timeout = 300
 
+######################################################################
+# DSCP value for sent RTP packets
+#    The Differentiated Service Code Point is a selector for
+#    router's per-hop behaviours.
+#    RFC2598 defined a "expedited forwarding" service. This service
+#    is designed to allow ISPs to offer a service with attributes
+#    similar to a "leased line". This service offers the ULTIMATE IN LOW
+#    LOSS, LOW LATENCY AND LOW JITTER by ensuring that there is always
+#    sufficent room in output queues for the contracted expedited forwarding
+#    traffic.
+#    The Expedited Forwarding service has a DSCP of 46.
+#    Putting a 0 here means that siproxd does NOT set the DSCP field.
+#    Siproxd must be started as root for this to work.
+#
+rtp_dscp = 46
+
 ######################################################################
 # Default Expiration timeout for Registrations
 #    If a REGISTER request does not contain an Expires header

src/readconf.c

@@ -155,6 +155,7 @@ static int parse_config (FILE *configfile) {
       { "rtp_port_high",       TYP_INT4,   &configuration.rtp_port_high },
       { "rtp_timeout",         TYP_INT4,   &configuration.rtp_timeout },
       { "rtp_proxy_enable",    TYP_INT4,   &configuration.rtp_proxy_enable },
+      { "rtp_dscp",            TYP_INT4,   &configuration.rtp_dscp },
       { "user",                TYP_STRING, &configuration.user },
       { "chrootjail",          TYP_STRING, &configuration.chrootjail },
       { "hosts_allow_reg",     TYP_STRING, &configuration.hosts_allow_reg },

src/rtpproxy_relay.c

@@ -395,6 +395,7 @@ int rtp_relay_start_fwd (osip_call_id_t *callid, char *client_id,
    int sock, port;
    int freeidx;
    int sts=STS_SUCCESS;
+   int tos;
    osip_call_id_t cid;
    
 
@@ -566,6 +567,35 @@ int rtp_relay_start_fwd (osip_call_id_t *callid, char *client_id,
       goto unlock_and_exit;
    }
 
+   /* set DSCP value, need to be ROOT */
+   if (configuration.rtp_dscp) {
+      int uid,euid;
+      uid=getuid();
+      euid=geteuid();
+      DEBUGC(DBCLASS_RTP,"uid=%i, euid=%i", uid, euid);
+      if (uid != euid) seteuid(0);
+      if (geteuid()==0) {
+         /* now I'm root */
+         if (!(configuration.rtp_dscp & ~0x3f)) {
+            tos = (configuration.rtp_dscp << 2) & 0xff;
+            if(setsockopt(sock, SOL_IP, IP_TOS, &tos, sizeof(tos))) {
+               ERROR("rtp_relay_start_fwd: setsockopt() failed while "
+                     "setting DSCP value: ", strerror(errno));
+            }
+         } else {
+            ERROR("rtp_relay_start_fwd: Invalid DSCP value %d",
+                  configuration.rtp_dscp);
+            configuration.rtp_dscp = 0; /* inhibit further attempts */
+         }
+      } else {
+         /* could not get root */
+         WARN("siproxd not started as root - cannot set DSCP value");
+         configuration.rtp_dscp = 0; /* inhibit further attempts */
+      }
+      /* drop privileges */
+      if (uid != euid) seteuid(euid);
+   }
+
    /* write entry into rtp_proxytable slot (freeidx) */
    rtp_proxytable[freeidx].rtp_rx_sock=sock;
 

src/siproxd.h

@@ -67,6 +67,7 @@ struct siproxd_config {
    int rtp_port_low;
    int rtp_port_high;
    int rtp_timeout;
+   int rtp_dscp;
    int rtp_proxy_enable;
    char *user;
    char *chrootjail;