Handle link type DLT_EN10MB and DLT_RAW

atupone · Oct 2, 2023 · 74aea2d · 74aea2d
1 parent bd2bfc4
commit 74aea2d
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Showing 3 changed files with 31 additions and 21 deletions.
diff --git a/udpCallback.c b/udpCallback.c
@@ -55,6 +55,7 @@ long int countToFlood = 0;
 int    asterixTime = 0;
 int    setMulticastTTL = 0;
 long   multicastTTLValue = 0;
+int    datalink;
 
 void waitBeforeSending(struct timeval actual_delta)
 {
@@ -141,31 +142,33 @@ static void callback_handler(u_char *user __attribute__((unused)),
   if (caplen != len)
     return;
 
-  /* Copy the ethernet header */
-  if (len < sizeof(eth_hdr))
-    return;
-  memcpy(&eth_hdr, bytes, sizeof(eth_hdr));
-  bytes += sizeof(eth_hdr);
-  len   -= sizeof(eth_hdr);
+  if (datalink == DLT_EN10MB) {
+    /* Copy the ethernet header */
+    if (len < sizeof(eth_hdr))
+      return;
+    memcpy(&eth_hdr, bytes, sizeof(eth_hdr));
+    bytes += sizeof(eth_hdr);
+    len   -= sizeof(eth_hdr);
 
-  protocol = ntohs(eth_hdr.ether_type);
+    protocol = ntohs(eth_hdr.ether_type);
 
-  /* Check for VLAN data */
-  if (protocol == ETHERTYPE_VLAN)
-  {
-    /* Copy the vlan header */
-    if (len < sizeof(vlan_hdr))
-      return;
-    memcpy(&vlan_hdr, bytes, sizeof(vlan_hdr));
-    bytes += sizeof(vlan_hdr);
-    len   -= sizeof(vlan_hdr);
+    /* Check for VLAN data */
+    if (protocol == ETHERTYPE_VLAN)
+    {
+      /* Copy the vlan header */
+      if (len < sizeof(vlan_hdr))
+        return;
+      memcpy(&vlan_hdr, bytes, sizeof(vlan_hdr));
+      bytes += sizeof(vlan_hdr);
+      len   -= sizeof(vlan_hdr);
 
-    protocol = ntohs(vlan_hdr.vlan_tci);
-  }
+      protocol = ntohs(vlan_hdr.vlan_tci);
+    }
 
-  /* Discard non IP datagram */
-  if (protocol != ETHERTYPE_IP)
-    return;
+    /* Discard non IP datagram */
+    if (protocol != ETHERTYPE_IP)
+      return;
+  }
 
   /* Copy the IPv4 header */
   if (len < sizeof(ip_hdr))

diff --git a/udpCallback.h b/udpCallback.h
@@ -24,5 +24,6 @@ extern int oneByOne;
 extern int asterixTime;
 extern int  setMulticastTTL;
 extern long multicastTTLValue;
+extern int datalink;
 
 extern void replayAll(pcap_t *pcap);
diff --git a/udpReplay.c b/udpReplay.c
@@ -118,6 +118,12 @@ int main(int argc, char* argv[])
     return -1;
   }
 
+  datalink = pcap_datalink(pcap);
+
+  if (datalink != DLT_EN10MB)
+    if (datalink != DLT_RAW) {
+      printf("datalink = %i not handled\n", datalink);
+    }
   replayAll(pcap);
 
   return 0;