Remove some useless checks (#1993)

In the main dissector callbacks the flow protocols are (almost) always
unknown. Only two exceptions:
* extra dissection data path
* HTTP sub-protocols

1 files changed, 47 insertions, 52 deletions

diff --git a/src/lib/protocols/skype.c b/src/lib/protocols/skype.c
index d0d3c8060..bec650f25 100644
--- a/src/lib/protocols/skype.c
+++ b/src/lib/protocols/skype.c
@@ -43,59 +43,56 @@ static void ndpi_check_skype(struct ndpi_detection_module_struct *ndpi_struct, s
   if(flow->host_server_name[0] != '\0')
     return;
   
-  if(packet->udp != NULL) {    
-
-    if(flow->packet_counter < 5) {
-      u_int16_t sport = ntohs(packet->udp->source);
-      u_int16_t dport = ntohs(packet->udp->dest);
-
-      /* skype-to-skype */
-      if(is_port(sport, dport, 1119) /* It can be confused with battle.net */
-	 || is_port(sport, dport, 80) /* No HTTP-like protocols UDP/80 */
-	 ) {
-	;
-      } else {
-	/* Too many false positives */
-	if(((payload_len == 3) && ((packet->payload[2] & 0x0F)== 0x0d))
-	   ||
-	   ((payload_len >= 16)
-	    && (((packet->payload[0] & 0xC0) >> 6) == 0x02 /* RTPv2 */
-		|| (((packet->payload[0] & 0xF0) >> 4) == 0 /* Zoom */)
-		|| (((packet->payload[0] & 0xF0) >> 4) == 0x07 /* Skype */)
-		)
-	    && (packet->payload[0] != 0x30) /* Avoid invalid SNMP detection */
-	    && (packet->payload[0] != 0x00) /* Avoid invalid CAPWAP detection */
-	    && (packet->payload[2] == 0x02))) {
-
-	  if(is_port(sport, dport, 8801)) {
-	    NDPI_LOG_INFO(ndpi_struct, "found ZOOM (in SKYPE_TEAMS code)\n");
-	    ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_ZOOM, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
-	  } else if (payload_len >= 16 && packet->payload[0] != 0x01) /* Avoid invalid Cisco HSRP detection / RADIUS */ {
-	    NDPI_LOG_INFO(ndpi_struct, "found SKYPE_TEAMS\n");
-	    ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SKYPE_TEAMS_CALL, NDPI_PROTOCOL_SKYPE_TEAMS, NDPI_CONFIDENCE_DPI);
-	  }
+  if(flow->packet_counter < 5) {
+    u_int16_t sport = ntohs(packet->udp->source);
+    u_int16_t dport = ntohs(packet->udp->dest);
+
+    /* skype-to-skype */
+    if(is_port(sport, dport, 1119) /* It can be confused with battle.net */
+       || is_port(sport, dport, 80) /* No HTTP-like protocols UDP/80 */
+      ) {
+      ;
+    } else {
+      /* Too many false positives */
+      if(((payload_len == 3) && ((packet->payload[2] & 0x0F)== 0x0d))
+	 ||
+	 ((payload_len >= 16)
+	  && (((packet->payload[0] & 0xC0) >> 6) == 0x02 /* RTPv2 */
+	      || (((packet->payload[0] & 0xF0) >> 4) == 0 /* Zoom */)
+	      || (((packet->payload[0] & 0xF0) >> 4) == 0x07 /* Skype */)
+	     )
+	  && (packet->payload[0] != 0x30) /* Avoid invalid SNMP detection */
+	  && (packet->payload[0] != 0x00) /* Avoid invalid CAPWAP detection */
+	  && (packet->payload[2] == 0x02))) {
+
+	if(is_port(sport, dport, 8801)) {
+	  NDPI_LOG_INFO(ndpi_struct, "found ZOOM (in SKYPE_TEAMS code)\n");
+	  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_ZOOM, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
+	} else if (payload_len >= 16 && packet->payload[0] != 0x01) /* Avoid invalid Cisco HSRP detection / RADIUS */ {
+	  NDPI_LOG_INFO(ndpi_struct, "found SKYPE_TEAMS\n");
+	  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SKYPE_TEAMS_CALL, NDPI_PROTOCOL_SKYPE_TEAMS, NDPI_CONFIDENCE_DPI);
 	}
+      }
 
-        if (flow->detected_protocol_stack[0] == NDPI_PROTOCOL_UNKNOWN) {
-          const uint8_t id_flags_iv_crc_len = 11;
-          const uint8_t crc_len = sizeof(flow->l4.udp.skype_crc);
-          const uint8_t crc_offset = id_flags_iv_crc_len - crc_len;
-
-          /* Look for two pkts with the same crc */
-          if((payload_len >= id_flags_iv_crc_len) &&
-             (packet->payload[2] == 0x02 /* Payload flag */ )) {
-            if(flow->packet_counter == 1) {
-              memcpy(flow->l4.udp.skype_crc, &packet->payload[crc_offset], crc_len);
-            } else {
-              if(memcmp(flow->l4.udp.skype_crc, &packet->payload[crc_offset], crc_len) == 0) {
-                NDPI_LOG_INFO(ndpi_struct, "found SKYPE_TEAMS\n");
-                ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SKYPE_TEAMS, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
-                return;
-              }
+      if (flow->detected_protocol_stack[0] == NDPI_PROTOCOL_UNKNOWN) {
+        const uint8_t id_flags_iv_crc_len = 11;
+        const uint8_t crc_len = sizeof(flow->l4.udp.skype_crc);
+        const uint8_t crc_offset = id_flags_iv_crc_len - crc_len;
+
+        /* Look for two pkts with the same crc */
+        if((payload_len >= id_flags_iv_crc_len) &&
+           (packet->payload[2] == 0x02 /* Payload flag */ )) {
+          if(flow->packet_counter == 1) {
+            memcpy(flow->l4.udp.skype_crc, &packet->payload[crc_offset], crc_len);
+          } else {
+            if(memcmp(flow->l4.udp.skype_crc, &packet->payload[crc_offset], crc_len) == 0) {
+              NDPI_LOG_INFO(ndpi_struct, "found SKYPE_TEAMS\n");
+              ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SKYPE_TEAMS, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
+              return;
             }
-            /* No idea if the two pkts need to be consecutive; in doubt wait for some more pkts */
-            return;
           }
+          /* No idea if the two pkts need to be consecutive; in doubt wait for some more pkts */
+          return;
         }
       }
     }
@@ -109,9 +106,7 @@ static void ndpi_search_skype(struct ndpi_detection_module_struct *ndpi_struct,
 {
   NDPI_LOG_DBG(ndpi_struct, "search skype\n");
 
-  /* skip marked packets */
-  if(flow->detected_protocol_stack[0] != NDPI_PROTOCOL_SKYPE_TEAMS)
-    ndpi_check_skype(ndpi_struct, flow);
+  ndpi_check_skype(ndpi_struct, flow);
 }