This adds a "policy" hook into the logging framework's streams and
filters to replace the existing log filter predicates. The hook
signature is as follows:
hook(rec: any, id: Log::ID, filter: Log::Filter);
The logging manager invokes hooks on each log record. Hooks can veto
log records via a break, and modify them if necessary. Log filters
inherit the stream-level hook, but can override or remove the hook as
needed.
The distribution's existing log streams now come with pre-defined
hooks that users can add handlers to. Their name is standardized as
"log_policy" by convention, with additional suffixes when a module
provides multiple streams. The following adds a handler to the Conn
module's default log policy hook:
hook Conn::log_policy(rec: Conn::Info, id: Log::ID, filter: Log::Filter)
{
if ( some_veto_reason(rec) )
break;
}
By default, this handler will get invoked for any log filter
associated with the Conn::LOG stream.
The existing predicates are deprecated for removal in 4.1 but continue
to work.
This adds two new functions: `Conn::register_removal_hook()` and
`Conn::unregister_removal_hook()` for registering a hook function to be
called back during `connection_state_remove`. The benefit of using hook
callback approach is better scalability: the overhead of unrelated
protocols having to dispatch no-op `connection_state_remove` handlers is
avoided.
And switch Zeek's base scripts over to using it in place of
"connection_state_remove". The difference between the two is
that "connection_state_remove" is raised for all events while
"successful_connection_remove" excludes TCP connections that were never
established (just SYN packets). There can be performance benefits
to this change for some use-cases.
There's also a new event called ``connection_successful`` and a new
``connection`` record field named "successful" to help indicate this new
property of connections.
* martin/topic/fox/rfb:
Fixed issue in state machine
Some styling tweaks
Implement protocol confirmation
Analyzer and bro script for RFB protocol (VNC)
* <seth> I also applied a bit of clean up to the base
script to make it match other scripts better and
updated tests.
Do not set the service field in the bro script but
use the protocol confirmation paradigm.
Protocol is considered confirmed if both a
succesful client and server banner have been
parsed.
This analyzer parses the Remote Frame Buffer
protocol, usually referred to as the 'VNC protocol'.
It supports several dialects (3.3, 3.7, 3.8) and
also handles the Apple Remote Desktop variant.
It will log such facts as client/server versions,
authentication method used, authentication result,
height, width and name of the shared screen.
It also includes two testcases.
Todo: Apple Remote Desktop seems to have some
bytes prepended to the screen name. This is
not interepreted correctly.
