af-packet: add variable to disable offloading detection

This flag adds variable to disable offloading detection. The effect
of the flag is to avoid to transmit auxiliary data at each packet.
This could result in a potential performance gain.

src/runmode-af-packet.c

@@ -108,7 +108,7 @@ void *ParseAFPConfig(const char *iface)
     char *tmpclusterid;
     char *tmpctype;
     intmax_t value;
-    int dispromisc;
+    int boolval;
 
     if (iface == NULL) {
         return NULL;
@@ -125,6 +125,7 @@ void *ParseAFPConfig(const char *iface)
     aconf->cluster_id = 1;
     aconf->cluster_type = PACKET_FANOUT_HASH;
     aconf->promisc = 1;
+    aconf->detect_offload = 1;
     aconf->DerefFunc = AFPDerefConfig;
 
     /* Find initial node */
@@ -197,12 +198,20 @@ void *ParseAFPConfig(const char *iface)
         aconf->buffer_size = 0;
     }
 
-    ConfGetChildValueBool(if_root, "disable-promisc", (int *)&dispromisc);
-    if (dispromisc) {
+    ConfGetChildValueBool(if_root, "disable-promisc", (int *)&boolval);
+    if (boolval) {
         SCLogInfo("Disabling promiscuous mode on iface %s",
                 aconf->iface);
         aconf->promisc = 0;
     }
+    ConfGetChildValueBool(if_root, "detect-offload", (int *)&boolval);
+    if (! boolval) {
+        SCLogInfo("Disabling checksum offloading detection for %s",
+                aconf->iface);
+        aconf->detect_offload = 0;
+    }
+
+
 
     return aconf;
 }

src/source-af-packet.c

@@ -160,6 +160,7 @@ typedef struct AFPThreadVars_
     /* socket buffer size */
     int buffer_size;
     int promisc;
+    int detect_offload;
 
     int cluster_id;
     int cluster_type;
@@ -522,13 +523,18 @@ static int AFPCreateSocket(AFPThreadVars *ptv, char *devname, int verbose)
         }
     }
 
-{ int    val = 1;
-    if (setsockopt(ptv->socket, SOL_PACKET, PACKET_AUXDATA, &val,
-                sizeof(val)) == -1 && errno != ENOPROTOOPT) {
-/* FIXME */
-        return -1;
+    if (ptv->detect_offload) {
+        int    val = 1;
+        if (setsockopt(ptv->socket, SOL_PACKET, PACKET_AUXDATA, &val,
+                    sizeof(val)) == -1 && errno != ENOPROTOOPT) {
+            SCLogError(SC_ERR_AFP_CREATE,
+                    "Couldn't active auxdata on iface %s, error %s",
+                    devname,
+                    strerror(errno));
+            close(ptv->socket);
+            return -1;
+        }
     }
-}
 
     /* set socket recv buffer size */
     if (ptv->buffer_size != 0) {
@@ -607,6 +613,7 @@ TmEcode ReceiveAFPThreadInit(ThreadVars *tv, void *initdata, void **data) {
     ptv->buffer_size = afpconfig->buffer_size;
 
     ptv->promisc = afpconfig->promisc;
+    ptv->detect_offload = afpconfig->detect_offload;
 
     ptv->threads = 1;
 #ifdef HAVE_PACKET_FANOUT

src/source-af-packet.h

@@ -53,6 +53,8 @@ typedef struct AFPIfaceConfig_
     int cluster_type;
     /* promisc mode */
     int promisc;
+    /* no local packet */
+    int detect_offload;
     SC_ATOMIC_DECLARE(unsigned int, ref);
     void (*DerefFunc)(void *);
 } AFPIfaceConfig;

suricata.yaml

@@ -204,6 +204,9 @@ af-packet:
     # buffer-size: 32768
     # Set to yes to disable promiscuous mode
     # disable-promisc: no
+    # If your IDS do not treat any transmitted packets, you can set
+    # the following variable to no.
+    # detect-offload: yes
   - interface: eth1
     threads: 1
     cluster-id: 98