* Fixes#1528
* Serialization Interface should also fuzzed
* libjson-c may only be used in the unit test to verify the internal serialization interface
* Serialization Interface supports tlv(broken), csv and json
* Unit test does work again and requires libjson-c
Signed-off-by: lns <matzeton@googlemail.com>
At every fuzz iteration (i.e for every trace file):
* keep the same ndpi context (`ndpi_init_detection_module` is very
slow);
* reset the flow table, otherwise it grows indefinitely.
This change should fix the "out-of-memory" errors reported by oss-fuzz.
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.
Looking at `struct ndpi_flow_struct` the two bigger fields are
`host_server_name[240]` (mainly for HTTP hostnames and DNS domains) and
`protos.tls_quic.client_requested_server_name[256]`
(for TLS/QUIC SNIs).
This commit aims to reduce `struct ndpi_flow_struct` size, according to
two simple observations:
1) maximum one of these two fields is used for each flow. So it seems safe
to merge them;
2) even if hostnames/SNIs might be very long, in practice they are rarely
longer than a fews tens of bytes. So, using a (single) large buffer is a
waste of memory for all kinds of flows. If we need to truncate the name,
we keep the *last* characters, easing domain matching.
Analyzing some real traffic, it seems safe to assume that the vast
majority of hostnames/SNIs is shorter than 80 bytes.
Hostnames/SNIs are always converted to lowercase.
Attention was given so as to be sure that unit-tests outputs are not
affected by this change.
Because of a bug, TLS/QUIC SNI were always truncated to 64 bytes (the
*first* 64 ones): as a consequence, there were some "Suspicious DGA
domain name" and "TLS Certificate Mismatch" false positives.
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#1343Close#1342
`ndpiReader` is only an example, aiming to show nDPI capabilities
and integration, without any claim about performances.
Nonetheless its memory usage per flow is *huge*, limiting the kinds
of traces that we can test on a "normal" hardware (example: scan
attacks).
The key reason of that behaviour is that we preallocate all the memory
needed for *all* the available features.
Try to reduce memory usage simply allocating some structures only
when they are really needed. Most significant example: JOY algorithms.
This way we should use a lot less memory in the two most common
user-cases:
* `ndpiReader` invoked without any particular flag (i.e `ndpiReader -i
$FILENAME_OR_IFACE`)
* internal unit tests
Before (on x86_64):
```
struct ndpi_flow_info {
[...]
/* size: 7320, cachelines: 115, members: 72 */
```
After:
```
struct ndpi_flow_info {
[...]
/* size: 2128, cachelines: 34, members: 75 */
```
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.
Introduced in 5f7b9d802
reader_util.c: In function ‘process_ndpi_collected_info’:
reader_util.c:1148:60: warning: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size 64 [-Wformat-truncation=]
1148 | sizeof(flow->ssh_tls.client_requested_server_name), "%s",
| ^~
reader_util.c:1147:5: note: ‘snprintf’ output between 1 and 256 bytes into a destination of size 64
1147 | snprintf(flow->ssh_tls.client_requested_server_name,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1148 | sizeof(flow->ssh_tls.client_requested_server_name), "%s",
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1149 | flow->ndpi_flow->protos.tls_quic_stun.tls_quic.client_requested_server_name);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Some BSD APIs called in example/ return `struct bpf_timeval`, where nDPI
APIs expect `struct timeval`. These two structs, besides having
a different name, share the exact same set of fields.
NDPI_LOG* macros dereference ndpi_detection_module_struct object which is
private to ndpi library (via NDPI_LIB_COMPILATION define). So we can't use
them outside the library itself, i.e. in ndpiReader code
Therefore, in files in example/, convert all (rare) uses of NDPI_LOG* macros
to a new very simple macro, private to ndpiReader program. If necessary,
such macro may be improved.
According to a comment in ndpi_define.h, each dissector must define its own
NDPI_CURRENT_PROTO macro before including ndpi_api.h file
