Create capture dissector tables.

They are modeled after dissection dissector tables, but for the moment, don't have/need the flexibility.  They are intended to be much simpler/faster than full dissection.
The two most used/needed are "wtap_encap" and "ethertype", so they were the basis of starting to use and test capture dissector table API.  Others may be added in the future.

The "capture dissector" function signature needed a bit of tweeking to handling "claiming" of a packet.
The current application of this is capture functions returning TRUE if they affected a "type" of packet count.  Returning FALSE ends up considering the packet an "other" type.

Change-Id: I81d06a6ccb2c03665f087258a46b9d78d513d6cd
Reviewed-on: https://code.wireshark.org/review/12607
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 24 insertions, 35 deletions

diff --git a/epan/dissectors/packet-null.c b/epan/dissectors/packet-null.c
index 41d7b12cad..ee514ebdc9 100644
--- a/epan/dissectors/packet-null.c
+++ b/epan/dissectors/packet-null.c
@@ -65,7 +65,7 @@ static const value_string family_vals[] = {
 static dissector_handle_t ppp_hdlc_handle;
 static dissector_handle_t data_handle;
 
-static void
+static gboolean
 capture_null( const guchar *pd, int offset _U_, int len, packet_counts *ld, const union wtap_pseudo_header *pseudo_header _U_ )
 {
   guint32 null_header;
@@ -252,23 +252,21 @@ capture_null( const guchar *pd, int offset _U_, int len, packet_counts *ld, cons
    * digits would be zero and the next 2 hex digits would not be zero.
    * Furthermore, the third hex digit from the bottom would be <
    */
-  if (!BYTES_ARE_IN_FRAME(0, len, 2)) {
-    ld->other++;
-    return;
-  }
+  if (!BYTES_ARE_IN_FRAME(0, len, 2))
+    return FALSE;
+
   if (pd[0] == 0xFF && pd[1] == 0x03) {
     /*
      * Hand it to PPP.
      */
-    capture_ppp_hdlc(pd, 0, len, ld, pseudo_header);
+    return capture_ppp_hdlc(pd, 0, len, ld, pseudo_header);
   } else {
     /*
      * Treat it as a normal DLT_NULL header.
      */
-    if (!BYTES_ARE_IN_FRAME(0, len, (int)sizeof(null_header))) {
-      ld->other++;
-      return;
-    }
+    if (!BYTES_ARE_IN_FRAME(0, len, (int)sizeof(null_header)))
+      return FALSE;
+
     memcpy((char *)&null_header, (const char *)&pd[0], sizeof(null_header));
 
     if ((null_header & 0xFFFF0000) != 0) {
@@ -317,56 +315,47 @@ capture_null( const guchar *pd, int offset _U_, int len, packet_counts *ld, cons
      * BSD derivatives have different values?).
      */
     if (null_header > IEEE_802_3_MAX_LEN)
-      capture_ethertype((guint16) null_header, pd, 4, len, ld, pseudo_header);
+      return try_capture_dissector("ethertype", null_header, pd, 4, len, ld, pseudo_header);
     else {
 
       switch (null_header) {
 
       case BSD_AF_INET:
-        capture_ip(pd, 4, len, ld, pseudo_header);
-        break;
+        return capture_ip(pd, 4, len, ld, pseudo_header);
 
       case BSD_AF_INET6_BSD:
       case BSD_AF_INET6_FREEBSD:
       case BSD_AF_INET6_DARWIN:
-        capture_ipv6(pd, 4, len, ld, pseudo_header);
-        break;
-
-      default:
-        ld->other++;
-        break;
+        return capture_ipv6(pd, 4, len, ld, pseudo_header);
       }
     }
   }
+
+  return FALSE;
 }
 
-static void
+static gboolean
 capture_loop( const guchar *pd, int offset _U_, int len, packet_counts *ld, const union wtap_pseudo_header *pseudo_header _U_ )
 {
   guint32 loop_family;
 
-  if (!BYTES_ARE_IN_FRAME(0, len, (int)sizeof(loop_family))) {
-    ld->other++;
-    return;
-  }
+  if (!BYTES_ARE_IN_FRAME(0, len, (int)sizeof(loop_family)))
+    return FALSE;
+
   loop_family = pntoh32(&pd[0]);
 
   switch (loop_family) {
 
   case BSD_AF_INET:
-    capture_ip(pd, 4, len, ld, pseudo_header);
-    break;
+    return capture_ip(pd, 4, len, ld, pseudo_header);
 
   case BSD_AF_INET6_BSD:
   case BSD_AF_INET6_FREEBSD:
   case BSD_AF_INET6_DARWIN:
-    capture_ipv6(pd, 4, len, ld, pseudo_header);
-    break;
-
-  default:
-    ld->other++;
-    break;
+    return capture_ipv6(pd, 4, len, ld, pseudo_header);
   }
+
+  return FALSE;
 }
 
 static int
@@ -535,9 +524,6 @@ proto_register_null(void)
   proto_register_field_array(proto_null, hf, array_length(hf));
   proto_register_subtree_array(ett, array_length(ett));
 
-  register_capture_dissector(WTAP_ENCAP_NULL, capture_null, proto_null);
-  register_capture_dissector(WTAP_ENCAP_LOOP, capture_loop, proto_null);
-
   /* subdissector code */
   null_dissector_table = register_dissector_table("null.type",
                                                   "Null type", FT_UINT32, BASE_DEC, DISSECTOR_TABLE_NOT_ALLOW_DUPLICATE);
@@ -562,6 +548,9 @@ proto_reg_handoff_null(void)
 
   loop_handle = create_dissector_handle(dissect_loop, proto_null);
   dissector_add_uint("wtap_encap", WTAP_ENCAP_LOOP, loop_handle);
+
+  register_capture_dissector("wtap_encap", WTAP_ENCAP_NULL, capture_null, proto_null);
+  register_capture_dissector("wtap_encap", WTAP_ENCAP_LOOP, capture_loop, proto_null);
 }
 
 /*