Basically:
* "classification by-ip" (i.e. `flow->guessed_protocol_id_by_ip` is
NEVER returned in the protocol stack (i.e.
`flow->detected_protocol_stack[]`);
* if the application is interested into such information, it can access
`ndpi_protocol->protocol_by_ip` itself.
There are mainly 4 points in the code that set the "classification
by-ip" in the protocol stack: the generic `ndpi_set_detected_protocol()`/
`ndpi_detection_giveup()` functions and the HTTP/STUN dissectors.
In the unit tests output, a print about `ndpi_protocol->protocol_by_ip`
has been added for each flow: the huge diff of this commit is mainly due
to that.
Strictly speaking, this change is NOT an API/ABI breakage, but there are
important differences in the classification results. For examples:
* TLS flows without the initial handshake (or without a matching
SNI/certificate) are simply classified as `TLS`;
* similar for HTTP or QUIC flows;
* DNS flows without a matching request domain are simply classified as
`DNS`; we don't have `DNS/Google` anymore just because the server is
8.8.8.8 (that was an outrageous behaviour...);
* flows previusoly classified only "by-ip" are now classified as
`NDPI_PROTOCOL_UNKNOWN`.
See #1425 for other examples of why adding the "classification by-ip" in
the protocol stack is a bad idea.
Please, note that IPV6 is not supported :( (long standing issue in nDPI) i.e.
`ndpi_protocol->protocol_by_ip` wil be always `NDPI_PROTOCOL_UNKNOWN` for
IPv6 flows.
Define `NDPI_CONFIDENCE_MATCH_BY_IP` has been removed.
Close#1687
The host automa is used for two tasks:
* protocol sub-classification (obviously);
* DGA evaluation: the idea is that if a domain is present in this
automa, it can't be a DGA, regardless of its format/name.
In most dissectors both checks are executed, i.e. the code is something
like:
```
ndpi_match_host_subprotocol(..., flow->host_server_name, ...);
ndpi_check_dga_name(..., flow->host_server_name,...);
```
In that common case, we can perform only one automa lookup: if we check the
sub-classification before the DGA, we can avoid the second lookup in
the DGA function itself.
Add (basic) internal stats to the main data structures used by the
library; they might be usefull to check how effective these structures
are.
Add an option to `ndpiReader` to dump them; enabled by default in the
unit tests.
This new option enables/disables dumping of "num dissectors calls"
values, too (see b4cb14ec).
As a general rule, the higher the confidence value, the higher the
"reliability/precision" of the classification.
In other words, this new field provides an hint about "how" the flow
classification has been obtained.
For example, the application may want to ignore classification "by-port"
(they are not real DPI classifications, after all) or give a second
glance at flows classified via LRU caches (because of false positives).
Setting only one value for the confidence field is a bit tricky: more
work is probably needed in the next future to tweak/fix/improve the logic.
The goal is to have a (roughly) idea about how many packets nDPI needs
to properly classify a flow.
Log this information (and guessed flows number too) during unit tests,
to keep track of improvements/regressions across commits.
Simplified the process of adding lines to AC_AUTOMATA_t.
Use the ndpi_string_to_automa() function to add patterns with domain names.
For other cases can use ndpi_add_string_value_to_automa().
ac_automata_feature(ac_automa, AC_FEATURE_LC) allows adding
and compare data in a case insensitive manner. For mandatory pattern comparison
from the end of the line, the "ac_pattern.rep.at_end=1" flag is used.
This eliminated unnecessary conversions to lowercase and adding "$" for
end-of-line matching in domain name patterns.
ac_match_handler() has been renamed ac_domain_match_handler() and has been greatly simplified.
ac_domain_match_handler() looks for the template with the highest domain level.
For special cases it is possible to manually specify the domain level.
Added test for checking ambiguous domain names like:
- short.weixin.qq.com is QQ, not Wechat
- instagram.faae1-1.fna.fbcdn.net is Instagram, not Facebook
If you specify a NULL handler when creating the AC_AUTOMATA_t structure,
then a pattern with the maximum length that satisfies the search conditions will be found
(exact match, from the beginning of the string, from the end of the string, or a substring).
Added debugging for ac_automata_search.
To do this, you need to enable debugging globally using ac_automata_enable_debug(1) and
enable debugging in the AC_AUTOMATA_t structure using ac_automata_name("name", AC_FEATURE_DEBUG).
The search will display "name" and a list of matching patterns.
Running "AHO_DEBUG=1 ndpiReader ..." will show the lines that were searched for templates
and which templates were found.
The ac_automata_dump() prototype has been changed. Now it outputs data to a file.
If it is specified as NULL, then the output will be directed to stdout.
If you need to get data as a string, then use open_memstream().
Added the ability to run individual tests via the do.sh script
