netflow: fix ttl logic

Use a per direction TTL min and max so we can log different values
seen in the two half flows.

Signed-off-by: Eric Leblond <eric@regit.org>

src/flow.c

@@ -266,6 +266,29 @@ static inline int FlowUpdateSeenFlag(const Packet *p)
     return 1;
 }
 
+static inline void FlowUpdateTTL(Flow *f, Packet *p, uint8_t ttl)
+{
+    if (FlowGetPacketDirection(f, p) == TOSERVER) {
+        if (ttl < f->min_ttl_toserver) {
+            f->min_ttl_toserver = ttl;
+        } else if (f->min_ttl_toserver == 0) {
+            f->min_ttl_toserver = ttl;
+        }
+        if (ttl > f->max_ttl_toserver) {
+            f->max_ttl_toserver = ttl;
+        }
+    } else {
+        if (ttl < f->min_ttl_toclient) {
+            f->min_ttl_toclient = ttl;
+        } else if (f->min_ttl_toclient == 0) {
+            f->min_ttl_toclient = ttl;
+        }
+        if (ttl > f->max_ttl_toclient) {
+            f->max_ttl_toclient = ttl;
+        }
+    }
+}
+
 /** \brief Update Packet and Flow
  *
  *  Updates packet and flow based on the new packet.
@@ -349,18 +372,10 @@ void FlowHandlePacketUpdate(Flow *f, Packet *p)
     /* update flow's ttl fields if needed */
     if (PKT_IS_IPV4(p)) {
         uint8_t ttl = IPV4_GET_IPTTL(p);
-        if (ttl < f->min_ttl) {
-            f->min_ttl = ttl;
-        } else if (ttl > f->max_ttl) {
-            f->max_ttl = ttl;
-        }
+        FlowUpdateTTL(f, p, ttl);
     } else if (PKT_IS_IPV6(p)) {
         uint8_t ttl = IPV6_GET_HLIM(p);
-        if (ttl < f->min_ttl) {
-            f->min_ttl = ttl;
-        } else if (ttl > f->max_ttl) {
-            f->max_ttl = ttl;
-        }
+        FlowUpdateTTL(f, p, ttl);
     }
 }
 

src/flow.h

@@ -184,13 +184,13 @@ typedef struct AppLayerParserState_ AppLayerParserState;
     } while (0)
 
 #define FLOW_SET_IPV4_TTL_FROM_PACKET(p, f) do {    \
-        (f)->min_ttl = IPV4_GET_IPTTL((p));         \
-        (f)->max_ttl = IPV4_GET_IPTTL((p));         \
+        (f)->min_ttl_toserver = IPV4_GET_IPTTL((p));         \
+        (f)->max_ttl_toserver = IPV4_GET_IPTTL((p));         \
     } while (0)
 
 #define FLOW_SET_IPV6_HLIM_FROM_PACKET(p, f) do {   \
-        (f)->min_ttl = IPV6_GET_HLIM((p));          \
-        (f)->max_ttl = IPV6_GET_HLIM((p));          \
+        (f)->min_ttl_toserver = IPV6_GET_HLIM((p));          \
+        (f)->max_ttl_toserver = IPV6_GET_HLIM((p));          \
     } while (0)
 
 /* pkt flow flags */
@@ -340,8 +340,10 @@ typedef struct Flow_
     };
     uint8_t proto;
     uint8_t recursion_level;
-    uint8_t min_ttl;
-    uint8_t max_ttl;
+    uint8_t min_ttl_toserver;
+    uint8_t max_ttl_toserver;
+    uint8_t min_ttl_toclient;
+    uint8_t max_ttl_toclient;
     uint16_t vlan_id[2];
 
     /** flow hash - the flow hash before hash table size mod. */

src/output-json-netflow.c

@@ -214,8 +214,8 @@ static void JsonNetFlowLogJSONToServer(JsonNetFlowLogThread *aft, json_t *js, Fl
     json_object_set_new(hjs, "age",
             json_integer(age));
 
-    json_object_set_new(hjs, "min_ttl", json_integer(f->min_ttl));
-    json_object_set_new(hjs, "max_ttl", json_integer(f->max_ttl));
+    json_object_set_new(hjs, "min_ttl", json_integer(f->min_ttl_toserver));
+    json_object_set_new(hjs, "max_ttl", json_integer(f->max_ttl_toserver));
 
     json_object_set_new(js, "netflow", hjs);
 
@@ -266,6 +266,12 @@ static void JsonNetFlowLogJSONToClient(JsonNetFlowLogThread *aft, json_t *js, Fl
     json_object_set_new(hjs, "age",
             json_integer(age));
 
+    /* To client is zero if we did not see any packet */
+    if (f->max_ttl_toclient) {
+        json_object_set_new(hjs, "min_ttl", json_integer(f->min_ttl_toclient));
+        json_object_set_new(hjs, "max_ttl", json_integer(f->max_ttl_toclient));
+    }
+
     json_object_set_new(js, "netflow", hjs);
 
     /* TCP */