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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.
50 lines
1.9 KiB
Text
50 lines
1.9 KiB
Text
##! Interface for the ascii input reader.
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##!
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##! The defaults are set to match Bro's ASCII output.
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module InputAscii;
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export {
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## Separator between fields.
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## Please note that the separator has to be exactly one character long.
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const separator = Input::separator &redef;
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## Separator between set and vector elements.
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## Please note that the separator has to be exactly one character long.
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const set_separator = Input::set_separator &redef;
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## String to use for empty fields.
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const empty_field = Input::empty_field &redef;
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## String to use for an unset &optional field.
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const unset_field = Input::unset_field &redef;
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## Fail on invalid lines. If set to false, the ascii
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## input reader will jump over invalid lines, reporting
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## warnings in reporter.log. If set to true, errors in
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## input lines will be handled as fatal errors for the
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## reader thread; reading will abort immediately and
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## an error will be logged to reporter.log.
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## Individual readers can use a different value using
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## the $config table.
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## fail_on_invalid_lines = T was the default behavior
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## until Bro 2.6.
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const fail_on_invalid_lines = F &redef;
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## Fail on file read problems. If set to true, the ascii
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## input reader will fail when encountering any problems
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## while reading a file different from invalid lines.
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## Examples of such problems are permission problems, or
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## missing files.
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## When set to false, these problems will be ignored. This
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## has an especially big effect for the REREAD mode, which will
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## seamlessly recover from read errors when a file is
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## only temporarily inaccessible. For MANUAL or STREAM files,
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## errors will most likely still be fatal since no automatic
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## re-reading of the file is attempted.
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## Individual readers can use a different value using
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## the $config table.
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## fail_on_file_problem = T was the default behavior
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## until Bro 2.6.
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const fail_on_file_problem = F &redef;
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}
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