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

1 files changed, 3 insertions, 3 deletions

diff --git a/src/lib/protocols/http.c b/src/lib/protocols/http.c
index 932b0f451..cef8b3cfc 100644
--- a/src/lib/protocols/http.c
+++ b/src/lib/protocols/http.c
@@ -574,9 +574,9 @@ static void check_content_type_and_change_protocol(struct ndpi_detection_module_
     if(len > 0) ndpi_check_dga_name(ndpi_struct, flow, (char*)flow->host_server_name, 1);
 
     if(packet->forwarded_line.ptr) {
-      len = ndpi_min(packet->forwarded_line.len, sizeof(flow->protos.http.nat_ip)-1);
-      strncpy((char*)flow->protos.http.nat_ip, (char*)packet->forwarded_line.ptr, len);
-      flow->protos.http.nat_ip[len] = '\0';
+      len = ndpi_min(packet->forwarded_line.len, sizeof(flow->http.nat_ip)-1);
+      strncpy((char*)flow->http.nat_ip, (char*)packet->forwarded_line.ptr, len);
+      flow->http.nat_ip[len] = '\0';
     }
 
     ndpi_http_parse_subprotocol(ndpi_struct, flow);