Fix writes to `flow->protos` union fields (#1354)

We can write to `flow->protos` only after a proper classification.

This issue has been found in Kerberos, DHCP, HTTP, STUN, IMO, FTP,
SMTP, IMAP and POP code.
There are two kinds of fixes:
 * write to `flow->protos` only if a final protocol has been detected
 * move protocol state out of `flow->protos`
The hard part is to find, for each protocol, the right tradeoff between
memory usage and code complexity.

Handle Kerberos like DNS: if we find a request, we set the protocol
and an extra callback to further parsing the reply.

For all the other protocols, move the state out of `flow->protos`. This
is an issue only for the FTP/MAIL stuff.

Add DHCP Class Identification value to the output of ndpiReader and to
the Jason serialization.

Extend code coverage of fuzz tests.

Close #1343
Close #1342

2 files changed, 9 insertions, 3 deletions

diff --git a/fuzz/Makefile.am b/fuzz/Makefile.am
index ade21ac5a..dc149968a 100644
--- a/fuzz/Makefile.am
+++ b/fuzz/Makefile.am
@@ -46,7 +46,7 @@ fuzz_ndpi_reader_with_main_LINK=$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS
 
 # required for Google oss-fuzz
 # see https://github.com/google/oss-fuzz/tree/master/projects/ndpi
-testpcaps := $(wildcard ../tests/pcap/*.pcap)
+testpcaps := $(wildcard ../tests/pcap/*.pcap*)
 
 fuzz_ndpi_reader_seed_corpus.zip: $(testpcaps)
 	zip -r fuzz_ndpi_reader_seed_corpus.zip $(testpcaps)
diff --git a/fuzz/fuzz_process_packet.c b/fuzz/fuzz_process_packet.c
index 9efd80799..b8780b7a8 100644
--- a/fuzz/fuzz_process_packet.c
+++ b/fuzz/fuzz_process_packet.c
@@ -8,13 +8,18 @@ struct ndpi_id_struct *src;
 struct ndpi_id_struct *dst;
 
 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  uint8_t protocol_was_guessed;
+
   if (ndpi_info_mod == NULL) {
-    ndpi_info_mod = ndpi_init_detection_module(ndpi_no_prefs);
-    NDPI_PROTOCOL_BITMASK all;
+    ndpi_info_mod = ndpi_init_detection_module(ndpi_enable_ja3_plus);
+    NDPI_PROTOCOL_BITMASK all, debug_bitmask;
     NDPI_BITMASK_SET_ALL(all);
+    NDPI_BITMASK_SET_ALL(debug_bitmask);
     ndpi_set_protocol_detection_bitmask2(ndpi_info_mod, &all);
     src = ndpi_malloc(SIZEOF_ID_STRUCT);
     dst = ndpi_malloc(SIZEOF_ID_STRUCT);
+    ndpi_set_log_level(ndpi_info_mod, 4);
+    ndpi_set_debug_bitmask(ndpi_info_mod, debug_bitmask);
     ndpi_finalize_initialization(ndpi_info_mod);
   }
 
@@ -23,6 +28,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
   memset(src, 0, SIZEOF_ID_STRUCT);
   memset(dst, 0, SIZEOF_ID_STRUCT);
   ndpi_detection_process_packet(ndpi_info_mod, ndpi_flow, Data, Size, 0, src, dst);
+  ndpi_detection_giveup(ndpi_info_mod, ndpi_flow, 1, &protocol_was_guessed);
   ndpi_free_flow(ndpi_flow);
 
   return 0;