dns,spdy,ssl-utils: fix export PDU

Dissectors registered with SSL must be registered for Export PDU to
work properly. Otherwise the dissector name could be NULL, resulting
in a capture file that cannot properly be dissected.

Add an assertion to ssl-utils to catch this situation. Note that this
results in an "wmem_alloc: assertion failed: (allocator->in_scope)"
report because these functions are possibly called in the protocol
handoff routines... Can be fixed later.

The DNS dissector is fixed by merging the UDP/TCP dissectors into a
single dns handle which recognizes TCP and then assumes the length
prefix if TCP.

Change-Id: If73b9b09a4682d66fb8fa026c42a3475648f9bf1
Reviewed-on: https://code.wireshark.org/review/13194
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

3 files changed, 15 insertions, 21 deletions

diff --git a/epan/dissectors/packet-dns.c b/epan/dissectors/packet-dns.c
index 3234cf2cb2..0d351398d4 100644
--- a/epan/dissectors/packet-dns.c
+++ b/epan/dissectors/packet-dns.c
@@ -419,9 +419,7 @@ static expert_field ei_dns_undecoded_option = EI_INIT;
 
 static dissector_table_t dns_tsig_dissector_table=NULL;
 
-/* Added to be able to configure DNS ports. */
-static dissector_handle_t dns_tcp_handle;
-static dissector_handle_t dns_udp_handle;
+static dissector_handle_t dns_handle;
 
 static range_t *global_dns_tcp_port_range;
 static range_t *global_dns_udp_port_range;
@@ -4094,40 +4092,36 @@ proto_reg_handoff_dns(void)
   static gboolean Initialized = FALSE;
 
   if (!Initialized) {
-    dissector_handle_t dns_sctp_handle;
     dissector_handle_t mdns_udp_handle;
     dissector_handle_t llmnr_udp_handle;
 
-    dns_udp_handle = create_dissector_handle(dissect_dns_udp_sctp, proto_dns);
-    dns_tcp_handle = create_dissector_handle(dissect_dns_tcp, proto_dns);
-    dns_sctp_handle  = create_dissector_handle(dissect_dns_udp_sctp, proto_dns);
     mdns_udp_handle  = create_dissector_handle(dissect_mdns_udp, proto_mdns);
     llmnr_udp_handle = create_dissector_handle(dissect_llmnr_udp, proto_llmnr);
     dissector_add_uint("udp.port", UDP_PORT_MDNS, mdns_udp_handle);
-    dissector_add_uint("tcp.port", TCP_PORT_MDNS, dns_tcp_handle);
+    dissector_add_uint("tcp.port", TCP_PORT_MDNS, dns_handle);
     dissector_add_uint("udp.port", UDP_PORT_LLMNR, llmnr_udp_handle);
-    dissector_add_uint("sctp.port", SCTP_PORT_DNS, dns_sctp_handle);
+    dissector_add_uint("sctp.port", SCTP_PORT_DNS, dns_handle);
 #if 0
-    dissector_add_uint("sctp.ppi",  DNS_PAYLOAD_PROTOCOL_ID, dns_sctp_handle);
+    dissector_add_uint("sctp.ppi",  DNS_PAYLOAD_PROTOCOL_ID, dns_handle);
 #endif
     stats_tree_register("dns", "dns", "DNS", 0, dns_stats_tree_packet, dns_stats_tree_init, NULL);
     gssapi_handle  = find_dissector("gssapi");
     ntlmssp_handle = find_dissector("ntlmssp");
-    ssl_dissector_add(TCP_PORT_DNS_TLS, dns_tcp_handle);
-    dtls_dissector_add(UDP_PORT_DNS_DTLS, dns_udp_handle);
+    ssl_dissector_add(TCP_PORT_DNS_TLS, dns_handle);
+    dtls_dissector_add(UDP_PORT_DNS_DTLS, dns_handle);
     Initialized    = TRUE;
 
   } else {
-    dissector_delete_uint_range("tcp.port", dns_tcp_port_range, dns_tcp_handle);
-    dissector_delete_uint_range("udp.port", dns_udp_port_range, dns_udp_handle);
+    dissector_delete_uint_range("tcp.port", dns_tcp_port_range, dns_handle);
+    dissector_delete_uint_range("udp.port", dns_udp_port_range, dns_handle);
     g_free(dns_tcp_port_range);
     g_free(dns_udp_port_range);
   }
 
   dns_tcp_port_range = range_copy(global_dns_tcp_port_range);
   dns_udp_port_range = range_copy(global_dns_udp_port_range);
-  dissector_add_uint_range("tcp.port", dns_tcp_port_range, dns_tcp_handle);
-  dissector_add_uint_range("udp.port", dns_udp_port_range, dns_udp_handle);
+  dissector_add_uint_range("tcp.port", dns_tcp_port_range, dns_handle);
+  dissector_add_uint_range("udp.port", dns_udp_port_range, dns_handle);
 }
 
 void
@@ -5620,7 +5614,7 @@ proto_register_dns(void)
 
   dns_tsig_dissector_table = register_dissector_table("dns.tsig.mac", "DNS TSIG MAC Dissectors", FT_STRING, BASE_NONE, DISSECTOR_TABLE_NOT_ALLOW_DUPLICATE);
 
-  register_dissector("dns", dissect_dns, proto_dns);
+  dns_handle = register_dissector("dns", dissect_dns, proto_dns);
 
   dns_tap = register_tap("dns");
 }
diff --git a/epan/dissectors/packet-spdy.c b/epan/dissectors/packet-spdy.c
index b1863f2083..5dca654bb7 100644
--- a/epan/dissectors/packet-spdy.c
+++ b/epan/dissectors/packet-spdy.c
@@ -1912,7 +1912,7 @@ void proto_register_spdy(void)
   expert_spdy = expert_register_protocol(proto_spdy);
   expert_register_field_array(expert_spdy, ei, array_length(ei));
 
-  register_dissector("spdy", dissect_spdy, proto_spdy);
+  spdy_handle = register_dissector("spdy", dissect_spdy, proto_spdy);
 
   spdy_module = prefs_register_protocol(proto_spdy, NULL);
   prefs_register_bool_preference(spdy_module, "assemble_data_frames",
@@ -1931,9 +1931,6 @@ void proto_register_spdy(void)
                                  "using \"Content-Encoding: \"",
                                  &spdy_decompress_body);
 
-  /** Create dissector handle and register for dissection. */
-  spdy_handle = create_dissector_handle(dissect_spdy, proto_spdy);
-
   register_init_routine(&spdy_init_protocol);
 
   /*
diff --git a/epan/dissectors/packet-ssl-utils.c b/epan/dissectors/packet-ssl-utils.c
index 3c40f53f72..c6570bb754 100644
--- a/epan/dissectors/packet-ssl-utils.c
+++ b/epan/dissectors/packet-ssl-utils.c
@@ -4152,6 +4152,9 @@ ssl_association_add(const char* dissector_table_name, dissector_handle_t main_ha
 {
     DISSECTOR_ASSERT(main_handle);
     DISSECTOR_ASSERT(subdissector_handle);
+    /* Registration is required for Export PDU feature to work properly. */
+    DISSECTOR_ASSERT_HINT(dissector_handle_get_dissector_name(subdissector_handle),
+            "SSL appdata dissectors must register with register_dissector()!");
     ssl_debug_printf("association_add %s port %d handle %p\n", dissector_table_name, port, (void *)subdissector_handle);
 
     if (port) {