af-packet: parse message to find lack of checksum

Emitted packet can have checksum offloading. This patch reads
af-packet message parameter to see if the kernel has sent a non
checksummed packet.

src/source-af-packet.c

@@ -228,22 +228,18 @@ int AFPRead(AFPThreadVars *ptv)
     struct sockaddr_ll from;
     struct iovec iov;
     struct msghdr msg;
-#if 0
     struct cmsghdr *cmsg;
     union {
         struct cmsghdr cmsg;
         char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))];
     } cmsg_buf;
-#endif
 
     msg.msg_name = &from;
     msg.msg_namelen = sizeof(from);
     msg.msg_iov = &iov;
     msg.msg_iovlen = 1;
-#if 0
     msg.msg_control = &cmsg_buf;
     msg.msg_controllen = sizeof(cmsg_buf);
-#endif
     msg.msg_flags = 0;
 
     if (ptv->cooked)
@@ -293,6 +289,21 @@ int AFPRead(AFPThreadVars *ptv)
     SCLogDebug("pktlen: %" PRIu32 " (pkt %p, pkt data %p)",
                GET_PKT_LEN(p), p, GET_PKT_DATA(p));
 
+    for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+        struct tpacket_auxdata *aux;
+
+        if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) ||
+                cmsg->cmsg_level != SOL_PACKET ||
+                cmsg->cmsg_type != PACKET_AUXDATA)
+            continue;
+
+        aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg);
+
+        if (aux->tp_status & TP_STATUS_CSUMNOTREADY) {
+            p->flags |= PKT_IGNORE_CHECKSUM;
+        }
+    }
+
     if (TmThreadsSlotProcessPkt(ptv->tv, ptv->slot, p) != TM_ECODE_OK) {
         TmqhOutputPacketpool(ptv->tv, p);
         SCReturnInt(AFP_FAILURE);
@@ -510,6 +521,15 @@ static int AFPCreateSocket(AFPThreadVars *ptv, char *devname, int verbose)
             return -1;
         }
     }
+
+{ int    val = 1;
+    if (setsockopt(ptv->socket, SOL_PACKET, PACKET_AUXDATA, &val,
+                sizeof(val)) == -1 && errno != ENOPROTOOPT) {
+/* FIXME */
+        return -1;
+    }
+}
+
     /* set socket recv buffer size */
     if (ptv->buffer_size != 0) {
         /*