add get_tag()

status.c

@@ -326,7 +326,7 @@ uint32_t send_poll(int fd,int ssrc){
 
 
 // Extract SSRC; 0 means not present (reserved value)
-int get_ssrc(uint8_t const *buffer,int length){
+uint32_t get_ssrc(uint8_t const *buffer,int length){
   uint8_t const *cp = buffer;
 
   while(cp - buffer < length){
@@ -360,6 +360,44 @@ int get_ssrc(uint8_t const *buffer,int length){
     }
     cp += optlen;
   }
+ done:;
+  return 0;
+}
+// Extract command tag
+uint32_t get_tag(uint8_t const *buffer,int length){
+  uint8_t const *cp = buffer;
+
+  while(cp - buffer < length){
+    enum status_type const type = *cp++; // increment cp to length field
+
+    if(type == EOL)
+      break; // end of list, no length
+
+    unsigned int optlen = *cp++;
+    if(optlen & 0x80){
+      // length is >= 128 bytes; fetch actual length from next N bytes, where N is low 7 bits of optlen
+      int length_of_length = optlen & 0x7f;
+      optlen = 0;
+      while(length_of_length > 0){
+	optlen <<= 8;
+	optlen |= *cp++;
+	length_of_length--;
+      }
+    }
+    if(cp - buffer + optlen >= length)
+      break; // invalid length; we can't continue to scan
+
+    switch(type){
+    case EOL: // Shouldn't get here
+      goto done;
+    case COMMAND_TAG:
+      return decode_int(cp,optlen);
+      break;
+    default:
+      break; // Ignore on this pass
+    }
+    cp += optlen;
+  }
  done:;
   return 0; // broadcast
 }

status.h

@@ -148,7 +148,8 @@ float decode_float(uint8_t const *,int);
 double decode_double(uint8_t const *,int);
 struct sockaddr *decode_socket(void *sock,uint8_t const *,int);
 char *decode_string(uint8_t const *,int,char *,int);
-int get_ssrc(uint8_t const *buffer,int length);
+uint32_t get_ssrc(uint8_t const *buffer,int length);
+uint32_t get_tag(uint8_t const *buffer,int length);
 
 void dump_metadata(uint8_t const *,int);