Right now, there is, in essence, a static mapping between flow protocols
and flow breeds.
Make it dynamic: allow to have different flows, with the same
classification but differents breeds. This is the same logic that we
already have for categories....
Preliminary work to support breed in category lists.
API change from the app POV: to get the flow breed don't use anymore
`ndpi_get_proto_breed()`, but access directly `struct ndpi_proto->breed`
The functions `ndpi_domain_classify_*()` and
`ndpi_get_host_domain_suffix()` now have a `u_int32_t` parameter as
`class_id` (instead of `u_int_16_t`), with the following logic:
```
class_id = (breed << 16) | category
```
instead of the old:
```
class_id = category
```
Please note that this change is back-compatible: if you are not
interested into breeds, you don't need to update the application code.
* Modified boundary check
nDPI fingeprint now defaults on client only (it can be changed via runtime configuration)
* Undated testcases
* Added lenght check
* Typo
- TCP fingerprint
- JA4 fingepriint
- TLS SHA1 certificate (if present), or JA3S fingerprint (is SHA1 is missing)
By default the fingerprint uses the client and server fingerprints (format 0)
and combines them. However you can chnge it format (eg. use only the client info,
format 1) with
--cfg NULL,metadata.ndpi_fingerprint_format,X
where X is the fingerprint format.
By default nDPI fingerprint is enabled but you can enable/disble it as follows
--cfg NULL,metadata.ndpi_fingerprint,0
The idea is to remove the limitation of only two protocols ("master" and
"app") in the flow classifcation.
This is quite handy expecially for STUN flows and, in general, for any
flows where there is some kind of transitionf from a cleartext protocol
to TLS: HTTP_PROXY -> TLS/Youtube; SMTP -> SMTPS (via STARTTLS msg).
In the vast majority of the cases, the protocol stack is simply
Master/Application.
Examples of real stacks (from the unit tests) different from the standard
"master/app":
* "STUN.WhatsAppCall.SRTP": a WA call
* "STUN.DTLS.GoogleCall": a Meet call
* "Telegram.STUN.DTLS.TelegramVoip": a Telegram call
* "SMTP.SMTPS.Google": a SMTP connection to Google server started in
cleartext and updated to TLS
* "HTTP.Google.ntop": a HTTP connection to a Google domain (match via
"Host" header) and to a ntop server (match via "Server" header)
The logic to create the stack is still a bit coarse: we have a decade of
code try to push everything in only ywo protocols... Therefore, the
content of the stack is still **highly experimental** and might change
in the next future; do you have any suggestions?
It is quite likely that the legacy fields "master_protocol" and
"app_protocol" will be there for a long time.
Add some helper to use the stack:
```
ndpi_stack_get_upper_proto();
ndpi_stack_get_lower_proto();
bool ndpi_stack_contains(struct ndpi_proto_stack *s, u_int16_t proto_id);
bool ndpi_stack_is_tls_like(struct ndpi_proto_stack *s);
bool ndpi_stack_is_http_like(struct ndpi_proto_stack *s);
```
Be sure new stack logic is compatible with legacy code:
```
assert(ndpi_stack_get_upper_proto(&flow->detected_protocol.protocol_stack) ==
ndpi_get_upper_proto(flow->detected_protocol));
assert(ndpi_stack_get_lower_proto(&flow->detected_protocol.protocol_stack) ==
ndpi_get_lower_proto(flow->detected_protocol));
```
Use `NDPI_OBFUSCATED_TRAFFIC` instead; this way, all the obfuscated
traffic is identified via `NDPI_OBFUSCATED_TRAFFIC` flow risk.
Disable fully-encryption detection by default, like all the obfuscation
heuristics.
This function is always called once for every flow, as last code
processing the flow itself.
As a first usage example, check here if the flow is unidirectional
(instead of checking it at every packets)
Removing JA3C is an big task. Let's start with a simple change having an
huge impact on unit tests: remove printing of JA3C information from
ndpiReader.
This way, when we will delete the actual code, the unit tests diffs
should be a lot simpler to look at.
Note that the information if the client/server cipher is weak or
obsolete is still available via flow risk
See: #2551
Based on the paper: "Fingerprinting Obfuscated Proxy Traffic with
Encapsulated TLS Handshakes".
See: https://www.usenix.org/conference/usenixsecurity24/presentation/xue-fingerprinting
Basic idea:
* the packets/bytes distribution of a TLS handshake is quite unique
* this fingerprint is still detectable if the handshake is
encrypted/proxied/obfuscated
All heuristics are disabled by default.
