Remove `struct ndpi_id_struct` (#1427)

Remove the last uses of `struct ndpi_id_struct`.
That code is not really used and it has not been updated for a very long
time: see #1279 for details.

Correlation among flows is achieved via LRU caches.

This change allows to further reduce memory consumption (see also
91bb77a8).

At nDPI 4.0 (more precisly, at a6b10cf, because memory stats
were wrong until that commit):
```
nDPI Memory statistics:
	nDPI Memory (once):      221.15 KB
	Flow Memory (per flow):  2.94 KB
```
Now:
```
nDPI Memory statistics:
	nDPI Memory (once):      235.27 KB
	Flow Memory (per flow):  688 B        <--------
```
i.e. memory usage per flow has been reduced by 77%.

Close #1279

1 files changed, 4 insertions, 61 deletions

diff --git a/src/lib/protocols/gnutella.c b/src/lib/protocols/gnutella.c
index 2af76085f..ecb93d53f 100644
--- a/src/lib/protocols/gnutella.c
+++ b/src/lib/protocols/gnutella.c
@@ -33,67 +33,18 @@ static void ndpi_int_gnutella_add_connection(struct ndpi_detection_module_struct
 					     struct ndpi_flow_struct *flow,
 					     ndpi_confidence_t confidence)
 {
-  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
-  struct ndpi_id_struct *src = flow->src;
-  struct ndpi_id_struct *dst = flow->dst;
-
   ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_GNUTELLA, NDPI_PROTOCOL_UNKNOWN, confidence);
   NDPI_LOG_INFO(ndpi_struct, "found GNUTELLA\n");
-
-  if (src != NULL) {
-    src->gnutella_ts = packet->current_time_ms;
-    if (packet->udp != NULL) {
-      if (!src->detected_gnutella_udp_port1) {
-	src->detected_gnutella_udp_port1 = (packet->udp->source);
-	NDPI_LOG_DBG2(ndpi_struct,
-		"GNUTELLA UDP PORT1 DETECTED as %u\n", src->detected_gnutella_udp_port1);
-
-      } else if ((ntohs(packet->udp->source) != src->detected_gnutella_udp_port1)
-		 && !src->detected_gnutella_udp_port2) {
-	src->detected_gnutella_udp_port2 = (packet->udp->source);
-	NDPI_LOG_DBG2(ndpi_struct,
-		"GNUTELLA UDP PORT2 DETECTED as %u\n", src->detected_gnutella_udp_port2);
-
-      }
-    }
-  }
-  if (dst != NULL) {
-    dst->gnutella_ts = packet->current_time_ms;
-  }
 }
 
 void ndpi_search_gnutella(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
 {
   struct ndpi_packet_struct *packet = &ndpi_struct->packet;
 	
-  struct ndpi_id_struct *src = flow->src;
-  struct ndpi_id_struct *dst = flow->dst;
   u_int16_t c;
 
   NDPI_LOG_DBG(ndpi_struct, "search GNUTELLA\n");
 
-  if (flow->detected_protocol_stack[0] == NDPI_PROTOCOL_GNUTELLA) {
-    if (src != NULL && ((u_int32_t)
-			(packet->current_time_ms - src->gnutella_ts) < ndpi_struct->gnutella_timeout)) {
-      NDPI_LOG_DBG2(ndpi_struct, "save src connection packet detected\n");
-      src->gnutella_ts = packet->current_time_ms;
-    } else if (dst != NULL && ((u_int32_t)
-			       (packet->current_time_ms - dst->gnutella_ts) < ndpi_struct->gnutella_timeout)) {
-      NDPI_LOG_DBG2(ndpi_struct, "save dst connection packet detected\n");
-      dst->gnutella_ts = packet->current_time_ms;
-    }
-    if (src != NULL && (packet->current_time_ms - src->gnutella_ts) > ndpi_struct->gnutella_timeout) {
-      src->detected_gnutella_udp_port1 = 0;
-      src->detected_gnutella_udp_port2 = 0;
-    }
-    if (dst != NULL && (packet->current_time_ms - dst->gnutella_ts) > ndpi_struct->gnutella_timeout) {
-      dst->detected_gnutella_udp_port1 = 0;
-      dst->detected_gnutella_udp_port2 = 0;
-    }
-
-    return;
-  }
-
   /* skip packets without payload */
   if (packet->payload_packet_len < 2) {
     return;
@@ -234,12 +185,6 @@ void ndpi_search_gnutella(struct ndpi_detection_module_struct *ndpi_struct, stru
       }
     }
   } else if (packet->udp != NULL) {
-    if (src != NULL && (packet->udp->source == src->detected_gnutella_udp_port1 ||
-			packet->udp->source == src->detected_gnutella_udp_port2) &&
-	(packet->current_time_ms - src->gnutella_ts) < ndpi_struct->gnutella_timeout) {
-      NDPI_LOG_DBG2(ndpi_struct, "port based detection\n\n");
-      ndpi_int_gnutella_add_connection(ndpi_struct, flow, NDPI_CONFIDENCE_DPI_SRC_DST_ID);
-    }
     /* observations:
      * all the following patterns send out many packets which are the only ones of their flows,
      * often on the very beginning of the traces, or flows with many packets in one direction only.
@@ -333,20 +278,18 @@ void ndpi_search_gnutella(struct ndpi_detection_module_struct *ndpi_struct, stru
       if (flow->packet_counter == 2 && (packet->payload_packet_len == 33 || packet->payload_packet_len == 22)
 	  && flow->l4.tcp.gnutella_msg_id[0] == packet->payload[0]
 	  && flow->l4.tcp.gnutella_msg_id[1] == packet->payload[2]
-	  && flow->l4.tcp.gnutella_msg_id[2] == packet->payload[4]
-	  && NDPI_SRC_OR_DST_HAS_PROTOCOL(src, dst, NDPI_PROTOCOL_GNUTELLA)) {
+	  && flow->l4.tcp.gnutella_msg_id[2] == packet->payload[4]) {
 	NDPI_LOG_DBG2(ndpi_struct, "GNUTELLA DETECTED due to message ID match (NEONet protocol)\n");
-	ndpi_int_gnutella_add_connection(ndpi_struct, flow, NDPI_CONFIDENCE_DPI_SRC_DST_ID);
+	ndpi_int_gnutella_add_connection(ndpi_struct, flow, NDPI_CONFIDENCE_DPI);
 	return;
       }
     } else if (flow->l4.tcp.gnutella_stage == 2 - packet->packet_direction) {
       if (flow->packet_counter == 2 && (packet->payload_packet_len == 10 || packet->payload_packet_len == 75)
 	  && flow->l4.tcp.gnutella_msg_id[0] == packet->payload[0]
 	  && flow->l4.tcp.gnutella_msg_id[1] == packet->payload[2]
-	  && flow->l4.tcp.gnutella_msg_id[2] == packet->payload[4]
-	  && NDPI_SRC_OR_DST_HAS_PROTOCOL(src, dst, NDPI_PROTOCOL_GNUTELLA)) {
+	  && flow->l4.tcp.gnutella_msg_id[2] == packet->payload[4]) {
 	NDPI_LOG_DBG2(ndpi_struct, "GNUTELLA DETECTED due to message ID match (NEONet protocol)\n");
-	ndpi_int_gnutella_add_connection(ndpi_struct, flow, NDPI_CONFIDENCE_DPI_SRC_DST_ID);
+	ndpi_int_gnutella_add_connection(ndpi_struct, flow, NDPI_CONFIDENCE_DPI);
 	return;
       }
     }