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, 1 insertions, 37 deletions

diff --git a/example/ndpiSimpleIntegration.c b/example/ndpiSimpleIntegration.c
index d8a83dc47..57b51450c 100644
--- a/example/ndpiSimpleIntegration.c
+++ b/example/ndpiSimpleIntegration.c
@@ -85,8 +85,6 @@ struct nDPI_flow_info {
   struct ndpi_proto guessed_protocol;
 
   struct ndpi_flow_struct * ndpi_flow;
-  struct ndpi_id_struct * ndpi_src;
-  struct ndpi_id_struct * ndpi_dst;
 };
 
 struct nDPI_workflow {
@@ -190,8 +188,6 @@ static void ndpi_flow_info_freer(void * const node)
 {
   struct nDPI_flow_info * const flow = (struct nDPI_flow_info *)node;
 
-  ndpi_free(flow->ndpi_dst);
-  ndpi_free(flow->ndpi_src);
   ndpi_flow_free(flow->ndpi_flow);
   ndpi_free(flow);
 }
@@ -505,10 +501,6 @@ static void ndpi_process_packet(uint8_t * const args,
   void * tree_result;
   struct nDPI_flow_info * flow_to_process;
 
-  int direction_changed = 0;
-  struct ndpi_id_struct * ndpi_src;
-  struct ndpi_id_struct * ndpi_dst;
-
   const struct ndpi_ethhdr * ethernet;
   const struct ndpi_iphdr * ip;
   struct ndpi_ipv6hdr * ip6;
@@ -753,9 +745,6 @@ static void ndpi_process_packet(uint8_t * const args,
     flow.dst_port = orig_src_port;
 
     tree_result = ndpi_tfind(&flow, &workflow->ndpi_flows_active[hashed_index], ndpi_workflow_node_cmp);
-    if (tree_result != NULL) {
-      direction_changed = 1;
-    }
 
     flow.ip_tuple.u32.src[0] = orig_src_ip[0];
     flow.ip_tuple.u32.src[1] = orig_src_ip[1];
@@ -800,20 +789,6 @@ static void ndpi_process_packet(uint8_t * const args,
     }
     memset(flow_to_process->ndpi_flow, 0, SIZEOF_FLOW_STRUCT);
 
-    flow_to_process->ndpi_src = (struct ndpi_id_struct *)ndpi_calloc(1, SIZEOF_ID_STRUCT);
-    if (flow_to_process->ndpi_src == NULL) {
-      fprintf(stderr, "[%8llu, %d, %4u] Not enough memory for src id struct\n",
-	      workflow->packets_captured, reader_thread->array_index, flow_to_process->flow_id);
-      return;
-    }
-
-    flow_to_process->ndpi_dst = (struct ndpi_id_struct *)ndpi_calloc(1, SIZEOF_ID_STRUCT);
-    if (flow_to_process->ndpi_dst == NULL) {
-      fprintf(stderr, "[%8llu, %d, %4u] Not enough memory for dst id struct\n",
-	      workflow->packets_captured, reader_thread->array_index, flow_to_process->flow_id);
-      return;
-    }
-
     printf("[%8llu, %d, %4u] new %sflow\n", workflow->packets_captured, thread_index,
 	   flow_to_process->flow_id,
 	   (flow_to_process->is_midstream_flow != 0 ? "midstream-" : ""));
@@ -821,19 +796,8 @@ static void ndpi_process_packet(uint8_t * const args,
       /* Possible Leak, but should not happen as we'd abort earlier. */
       return;
     }
-
-    ndpi_src = flow_to_process->ndpi_src;
-    ndpi_dst = flow_to_process->ndpi_dst;
   } else {
     flow_to_process = *(struct nDPI_flow_info **)tree_result;
-
-    if (direction_changed != 0) {
-      ndpi_src = flow_to_process->ndpi_dst;
-      ndpi_dst = flow_to_process->ndpi_src;
-    } else {
-      ndpi_src = flow_to_process->ndpi_src;
-      ndpi_dst = flow_to_process->ndpi_dst;
-    }
   }
 
   flow_to_process->packets_processed++;
@@ -884,7 +848,7 @@ static void ndpi_process_packet(uint8_t * const args,
   flow_to_process->detected_l7_protocol =
     ndpi_detection_process_packet(workflow->ndpi_struct, flow_to_process->ndpi_flow,
 				  ip != NULL ? (uint8_t *)ip : (uint8_t *)ip6,
-				  ip_size, time_ms, ndpi_src, ndpi_dst);
+				  ip_size, time_ms);
 
   if (ndpi_is_protocol_detected(workflow->ndpi_struct,
 				flow_to_process->detected_l7_protocol) != 0 &&