The configuration framework consists of three mostly distinct parts:
* option variables
* the config reader
* the script level framework
I will describe the three elements in the following.
Internally, this commit also performs a range of changes to the Input
manager; it marks a lot of functions as const and introduces a new
ValueToVal method (which could in theory replace the already existing
one - it is a bit more powerful).
This also changes SerialTypes to have a subtype for Values, just as
Fields already have it; I think it was mostly an oversight that this was
not introduced from the beginning. This should not necessitate any code
changes for people already using SerialTypes.
option variable
===============
The option keyword allows variables to be specified as run-tine options.
Such variables cannot be changed using normal assignments. Instead, they
can be changed using Option::set. It is possible to "subscribe" to
options and be notified when an option value changes.
Change handlers can also change values before they are applied; this
gives them the opportunity to reject changes. Priorities can be
specified if there are several handlers for one option.
Example script:
option testbool: bool = T;
function option_changed(ID: string, new_value: bool): bool
{
print fmt("Value of %s changed from %s to %s", ID, testbool, new_value);
return new_value;
}
event bro_init()
{
print "Old value", testbool;
Option::set_change_handler("testbool", option_changed);
Option::set("testbool", F);
print "New value", testbool;
}
config reader
=============
The config reader provides a way to read configuration files back into
Bro. Most importantly it automatically converts values to the correct
types. This is important because it is at least inconvenient (and
sometimes near impossible) to perform the necessary type conversions in
Bro scripts themselves. This is especially true for sets/vectors.
Configuration generally look like this:
[option name][tab/spaces][new variable value]
so, for example:
testaddr 2607:f8b0:4005:801::200e
testinterval 60
testtime 1507321987
test_set a b c d erdbeerschnitzel
The reader uses the option name to look up the type that variable has in
the Bro core and automatically converts the value to the correct type.
Example script use:
type Idx: record {
option_name: string;
};
type Val: record {
option_val: string;
};
global currconfig: table[string] of string = table();
event InputConfig::new_value(name: string, source: string, id: string, value: any)
{
print id, value;
}
event bro_init()
{
Input::add_table([$reader=Input::READER_CONFIG, $source="../configfile", $name="configuration", $idx=Idx, $val=Val, $destination=currconfig, $want_record=F]);
}
Script-level config framework
=============================
The script-level framework ties these two features together and makes
them a bit more convenient to use. Configuration files can simply be
specified by placing them into Config::config_files. The framework also
creates a config.log that shows all value changes that took place.
Usage example:
redef Config::config_files += {configfile};
export {
option testbool : bool = F;
}
The file is now monitored for changes; when a change occurs the
respective option values are automatically updated and the value change
is written to config.log.
- Generally increased the time allowed before they timeout.
- For tests w/ a clear termination condition (most of them), made
timeouts result in a test failure.
- Seemed to be a race in some cases between tests generating output and
the input reader stream getting removed/closed, so moved stream removal
closer to termination time, when all output should be available.
more cases.
It will now not only fire after table-reads have been completed,
but also after the last event of a whole-file-read (or whole-db-read, etc.).
The interface also has been extended a bit to allow readers to
directly fire the event should they so choose. This allows the
event to be fired in direct table-setting/event-sending modes,
which was previously not possible.
without a final \0 - which means that strings read by the input framework are
unusable by basically all internal functions (like to_count).
the basic test now also checks this.
Thanks at Sheharbano for noticing this.
Generally tried to make them more reliable and execute quicker.
They all now load the listen script as a trick to make sure input
sources are fully read, but also terminate() at appropriate times
so that they don't take more time than needed. They're also all
serialized with the 'comm' group so listening on a port doesn't
interfere with the communication tests.
compiles, not really tested.
basic test works 70% of the time, coredumps in the other 30 - but was not easy to debug on a first glance (most interestingly the crash happens in the logging framework - I wonder how that works).
Other tests are not adjusted to the new interface yet.
* change internal reader interface again
* remove some quite embarassing bugs that must have been in the interface for rather long
* add different read methods to script & internal interface (like normal, streaming, etc). Not implemented in ascii reader yet.
But: there are still a few places where I am sure that there are race conditions & memory leaks & I do not really like the current interface & I have to add a few more messages between the front and backend.
But - it works :)
