Asterisk PBX configuration syntax checker

AsteriskLint is a suite of tools to check syntax of your Asterisk PBX configuration files.

Alright, enough talking. Some examples please!

For an online example see https://asterisklint.osso.pub/. For CLI examples, keep reading:

Invocation

$ asterisklint
usage: asterisklint [-h] COMMAND
asterisklint: error: the following arguments are required: COMMAND

$ asterisklint ls
builtin:
  ls                    List available commands.

/usr/lib/python/dist-packages:
  dialplan-check        Do sanity checks on dialplan. Takes 'extensions.conf'
                        as argument. Suppress error classes using ALINT_IGNORE.
  dialplan-show         Show dialplan like Asterisk does with CLI command
                        "dialplan show". Takes 'extensions.conf' as argument.
  func_odbc-check       Do sanity checks on func_odbc.conf. Takes
                        'func_odbc.conf' as argument. Suppress error classes
                        using ALINT_IGNORE.
  ident-scan            Report similarly named contexts, labels and variables.
                        Takes 'extensions.conf' as argument. All parse errors
                        are suppressed.
  modules-show          Show which modules, apps and functions are used by the
                        dialplan. Takes 'extensions.conf' as argument.

Place custom commands in ~/.asterisklint/asterisklint/commands.

Take this little dialplan snippet, that we'll call extensions.conf:

[default]
exten => _8[2-9]x,1,NoOp
 same => n,GoSub(somewhere,s,1(argument1,argument2)
 same => n,Payback(audiofile)

Now run the dialplan-check command on it:

$ ALINT_IGNORE=H_DP_ asterisklint dialplan-check extensions.conf
extensions.conf:2 H_PAT_NON_CANONICAL: pattern '_8[2-9]x' is not in the canonical form '_8NX'
extensions.conf:3 W_APP_BAD_CASE: app 'GoSub' does not have the proper Case 'Gosub'
extensions.conf:3 W_APP_BALANCE: app data '1(argument1,argument2' looks like unbalanced parentheses/quotes/curlies
extensions.conf:4 E_APP_MISSING: app 'Payback' does not exist, dialplan will halt here!
extensions.conf:3 E_DP_GOTO_NOCONTEXT: context not found for goto to somewhere, s, 1

It had a lot to complain about that little snippet. But it was right. We even suppressed two hints about a missing [general] and [global] context using ALINT_IGNORE.

Not everything it checks is documented, and it does not check everything that we like yet. But it's a start. Bug reports are welcome. Feature requests prefer to be accompanied by a patch :-)

Try out modules-show if you use autoload=no in your modules.conf.

All commands show help if asked:

$ asterisklint modules-show --help
usage: asterisklint modules-show [-h] [--func-odbc FUNC_ODBC_CONF]
                                 [EXTENSIONS_CONF]

Show which modules, apps and functions are used by the dialplan. Useful when
you use autoload=no in your modules.conf. Beware that you do need more modules
than just these listed.

positional arguments:
  EXTENSIONS_CONF       path to extensions.conf

optional arguments:
  -h, --help            show this help message and exit
  --func-odbc FUNC_ODBC_CONF
                        path to func_odbc.conf, will be read automatically if
                        found in same the same dir as extensions.conf; set
                        empty to disable

Installation

Installation is a matter of python3 setup.py install. Or, for more convenience, install a PyPI uploaded version through pip3(1):

$ sudo pip3 install asterisklint
...
Successfully installed asterisklint

The dialplan-check comes in handy as a git commit hook, for example .git/hooks/pre-commit:

#!/bin/sh
export ALINT_IGNORE=  # adjust as needed

asterisklint dialplan-check PATH/TO/extensions.conf
ret=$?
if test $ret -ne 0; then
    echo >&2
    echo 'One or more dialplan syntax errors. Please fix before committing.' >&2
    exit $ret
fi

exit 0

TODO

• Expression parsing.

• Web: state is kept between requests:

  • on 500-error, the next user may get older errors (because of the messagedef singleton)
  • the BackGround/Background hack is stored between requests

• Log/store Set'd variables and compare against Read variables. Also log variables Set through the ARRAY() function. (And HASH?)

• Fix various includes issues:

  • Recursive #includes probably make asterisklint run out of stack.
  • Add checks for recursive dialplan-includes.
  • Scan for missing dialplan-includes.

• Trim CALLERID match (as used in FreePBX dialplan).

• Func_odbc parsing improvements:

  • check for missing synopsis/syntax (compare syntax to ARGn count)
  • check for correct usage of VAL (write only) and ARG and missing SQL_ESC
  • yield the odbc functions instead of contexts like it does now

  (See more in func_odbc.py.)

• Add app-check command to do dialplan checks of individual lines.

• Add expr-check command to do expression ($[...]) checks. E.g. add:

  exten => X!,1,Set(boolean=$["" <555> = 1234])
  ; Set(boolean=$[${CALLERID(all)} = 1234])
  ; incorrectly using 'all', should use 'num'
  ==> syntax error, unexpected '=', expecting '-' or '!' or '(' or '<token>'
  

• Allow multiline variables using += (key=val; key+=more-val).

• Investigate whether exten=>s,n(label)... exten=>s,label+10... is valid.

• For the Goto/Gosub-visiting:

  • Attempt to match contexts by regex if there are $VARs involved?
  • Allow a "noqa" style exceptions to be placed in a comment?

• Improve documentation as needed.

• Before 1.0, start adding versioning -- including semver -- so users can depend on a stable API from their custom scripts. Also version the scripts (commands) so they won't talk to older/newer libs if that poses a problem.

BUGS

• The library is very much in flux. Don't expect it to stabilize any time soon. Pay attention to versions!
• Multiline comments (;-- ... --;) are unsupported. Does anyone use those?
• Limits aren't checked (dialplan lines are limited at 255 or 8191 bytes for LOW_MEMORY and normal mode respectively).
• The library/suite is Python3 only. Right now the effort to make it Python2 compatible is larger than the demand. In the future Python2 compatibility will become even less relevant.

Author

Walter Doekes, OSSO B.V. 2015-2020