compiler: don't do the special VLAN stuff for NetAnalyzer Ethernet.

Restrict the special Linux VLAN stuff to DLT_EN10MB, as that's the type
for Linux Ethernet interfaces.

This makes the code a bit clearer.

diff --git a/gencode.c b/gencode.c
index d3c79e9246c9975091cbcdc55e351435510eb1ff..48ef46c538287fef88b537a265bfc698b81a76dc 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -9242,8 +9242,13 @@ gen_vlan(compiler_state_t *cstate, bpf_u_int32 vlan_num, int has_vlan_tag)
        switch (cstate->linktype) {
 
        case DLT_EN10MB:
-       case DLT_NETANALYZER:
-       case DLT_NETANALYZER_TRANSPARENT:
+               /*
+                * Newer version of the Linux kernel pass around
+                * packets in which the VLAN tag has been removed
+                * from the packet data and put into metadata.
+                *
+                * This requires special treatment.
+                */
 #if defined(SKF_AD_VLAN_TAG_PRESENT)
                /* Verify that this is the outer part of the packet and
                 * not encapsulated somehow. */
@@ -9265,10 +9270,24 @@ gen_vlan(compiler_state_t *cstate, bpf_u_int32 vlan_num, int has_vlan_tag)
                            has_vlan_tag);
                break;
 
+       case DLT_NETANALYZER:
+       case DLT_NETANALYZER_TRANSPARENT:
        case DLT_IEEE802_11:
        case DLT_PRISM_HEADER:
        case DLT_IEEE802_11_RADIO_AVS:
        case DLT_IEEE802_11_RADIO:
+               /*
+                * These are either Ethernet packets with an additional
+                * metadata header (the NetAnalyzer types), or 802.11
+                * packets, possibly with an additional metadata header.
+                *
+                * For the first of those, the VLAN tag is in the normal
+                * place, so the special-case handling above isn't
+                * necessary.
+                *
+                * For the second of those, we don't do the special-case
+                * handling for now.
+                */
                b0 = gen_vlan_no_bpf_extensions(cstate, vlan_num, has_vlan_tag);
                break;