debugger Module

Daniel-Constantin Mierla

asipto.com

Edited by

Daniel-Constantin Mierla


Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. cfgtrace (int)
3.2. breakpoint (int)
3.3. log_level (int)
3.4. log_facility (str)
3.5. log_prefix (str)
3.6. step_usleep (int)
3.7. step_loops (int)
4. Functions
4.1. dbg_breakpoint(mode)
5. Exported RPC Functions
5.1. dbg.ls
5.2. dbg.trace
5.3. dbg.bp
6. Usage

List of Examples

1.1. Set cfgtrace parameter
1.2. Set breakpoint parameter
1.3. Set log_level parameter
1.4. Set log_facility parameter
1.5. Set log_prefix parameter
1.6. Set step_usleep parameter
1.7. Set step_loops parameter
1.8. dbg_breakpoint usage

Chapter 1. Admin Guide

1. Overview

This module provides an interactive config file debugger. It can print a trace of config script execution for a SIP message to log and set breakpoints on every script action, allowing step-by-step execution of the routing and response scripts.

Debugging can be done from local or remote host via RPC interface (e.g., XMLRPC, kamcmd, siremis).

The framework to set breakpoints on specific actions and config lines is not exported to RPC. Each action can be accompanied by an breakpoint or you can use dbg_breakpoint() function to set a breakpoint at certain line. Global breakpoints can be enabled/disabled at runtime. The script running trace can also be enabled/disabled at runtime.

When the SIP router process is stopped at a breakpoint, you can investigate the values of any pseudo-variables. Note that some of pseudo-variables may produce memory leaks; a fix is planned in the future (here fall pseudo-variables with dynamic name such as htable, sqlops). References to SIP message, avps, headers, script and shared variables are safe.

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

  • none.

2.2. External Libraries or Applications

The following libraries or applications must be installed before running Kamailio with this module loaded:

  • None.

3. Parameters

3.1. cfgtrace (int)

Control whether the config script trace is enabled or disabled at startup. You can change the value at runtime without restart, globally or per process.

Default value is 0 (disabled).

Example 1.1. Set cfgtrace parameter

...
modparam("debugger", "cfgtrace", 1)
...

3.2. breakpoint (int)

Control whether every line (global) breakpoint is enabled or disabled at startup.

Default value is 0 (disabled).

Example 1.2. Set breakpoint parameter

...
modparam("debugger", "breakpoint", 1)
...

3.3. log_level (int)

What log level is to be used to print module-specific messages.

Default value is -1 (L_ERR).

Example 1.3. Set log_level parameter

...
modparam("debugger", "log_level", 1)
...

3.4. log_facility (str)

Which log facility is to be used to print module-specific messages. By using this setting, you can configure syslog to send debug messages to a separate log channel, like a specific kamailio-debug log file.

Default value is NULL (default from core).

Example 1.4. Set log_facility parameter

...
modparam("debugger", "log_facility", "LOG_DAEMON")
...

3.5. log_prefix (str)

String to print before any module-specific messages.

Default value is *** cfgtrace:.

Example 1.5. Set log_prefix parameter

...
modparam("debugger", "log_prefix", "from-debugger-with-love:")
...

3.6. step_usleep (int)

Microseconds to sleep before checking for new commands when waiting at a breakpoint.

Default value is 100000 (that is 0.1 sec).

Example 1.6. Set step_usleep parameter

...
modparam("debugger", "step_usleep", 500000)
...

3.7. step_loops (int)

How many sleeps of 'step_usleep' the RPC process performs when waiting for a reply from a worker process before responding to RPC. This avoids blocking RPC process forever in case the worker process 'forgets' to write back a reply.

Default value is 200.

Example 1.7. Set step_loops parameter

...
modparam("debugger", "step_loops", 100)
...

4. Functions

4.1.  dbg_breakpoint(mode)

Anchor a breakpoint at the current line of the config (the one on which this function is called). The 'mode' specifies whether the breakpoint is enabled (1) or disabled (0) at startup.

Note that this version of the module does not export this anchors to RPC for interactive debugging (temporarily disabled).

Example 1.8. dbg_breakpoint usage

...
if($si=="10.0.0.10")
	dbg_breakpoint("1");
...

5. Exported RPC Functions

5.1.  dbg.ls

List Kamailio processes with info related to interactive debugging.

Name: dbg.list

Parameters:

  • _pid_ : pid for which to list the details. If 'pid' is omitted then will print for all processes.

Examples of use with kamcmd:

		dbg.ls
		dbg.ls 1234

5.2.  dbg.trace

Control config script running trace.

Name: dbg.trace

Parameters:

  • _cmd_ : command can be 'on' or 'off' to enable or disable tracing for one or all processes.

  • _pid_ : pid for which to list the details. If 'pid' is omitted, then details for all processes will be printed.

Examples for using with kamcmd:

		dbg.trace on
		dbg.trace off
		dbg.trace on 1234

5.3.  dbg.bp

Control breakpoints and config execution.

Name: dbg.bp

Parameters:

  • _cmd_ : command, see next section for the list of available values.

  • _pid_ : process id for which to apply the command. If 'pid' is omitted, then the inner command will be applied to all processes.

  • _params_ : extra params specific for each command.

Commands:

  • on - turn on breakpoints. Pid parameter is optional.

  • off - turn off breakpoints. Pid parameter is optional.

  • keep - keep breakpoints only for pid given as parameter

  • release - disable breakpoints for processes that are not waiting at a breakpoint. Pid parameter is optional.

  • next - run the action under breakpoint and stop at next one (step by step execution). Pid parameter is mandatory.

  • move - run the action under breakpoint and remove the rest of breakpoints (continue execution without stopping again at next actions). Pid parameter is mandatory.

  • show - print details about the current breakpoint for pid. Pid parameter is mandatory.

  • eval - evaluate a pseudo-variable and print the result in RPC Pid parameter is mandatory.

  • log - evaluate a pseudo-variable and print the result in SIP router logs. Pid parameter is mandatory.

Examples for using with kamcmd:

		dbg.bp off
		dbg.bp on
		dbg.bp release
		dbg.bp on 1234
		dbg.bp eval 1234 $fu
		dbg.bp move 1234

6. Usage

A common usage is to investigate the execution path for a specific SIP message. Just enable cfg running trace, send the message and watch the logs.

Another typical usage is to do interactive debugging and run each line of the route blocks of the configuration file step-by-step for a particular SIP message.

You need to connect using kamcmd (or other RPC client) to Kamailio. Then you can enable cfg breakpoints and send the SIP message. One process will be in waiting state ('state' field different than 0 when you do dbg.ls). Calling dbg.release will set the other Kamailio processes in no-breakpoint mode so they can process other SIP messages without need to interact with them.

A process blocked at a breakpoint is waiting for a command. Use 'dbg.bp next pid' to execute the current action and stop at the next one. 'dbg.bp eval pid PV' can be used to retrieve the value of PV. Once you are done and want to continue the execution of the config wihtout interaction use 'dbg.bp move pid'.

Example of a session:

...
kamcmd> dbg.ls
{
	entry: 0
	pid: 6393
	set: 3
	state: 0
	in.pid: 0
	in.cmd: 0
}
{
	entry: 1
	pid: 6394
	set: 3
	state: 0
	in.pid: 0
	in.cmd: 0
}
...
{
	entry: 9
	pid: 6402
	set: 3
	state: 1
	in.pid: 0
	in.cmd: 0
}

kamcmd> dbg.bp show 6402
at bkp [/etc/kamailio/debugger.cfg:369] a=6 n=route

kamcmd> dbg.bp next 6402
exec [/etc/kamailio/debugger.cfg:369] a=6 n=route

kamcmd> dbg.bp next 6402
exec [/etc/kamailio/debugger.cfg:462] a=17 n=if

kamcmd> dbg.bp eval 6402 $fu
$fu : t=str v=sip:test@kamailio.org

kamcmd> dbg.bp move 6402
200 ok
...

Running the config trace looks like:

...
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=368 a=6 n=route
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=461 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=456 a=26 n=mf_process_maxfwd_header
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=466 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=461 a=27 n=sanity_check
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=371 a=6 n=route
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=659 a=3 n=return
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=374 a=6 n=route
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=501 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=470 a=25 n=has_totag
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=386 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=379 a=26 n=is_method
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=386 a=25 n=t_check_trans
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=389 a=6 n=route
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=643 a=3 n=return
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=393 a=26 n=remove_hf
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=398 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=394 a=26 n=is_method
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=404 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=398 a=26 n=is_method
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=404 a=6 n=route
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=682 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=409 a=6 n=route
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=575 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=550 a=26 n=is_method
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=551 a=3 n=return
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=412 a=6 n=route
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=518 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=505 a=26 n=is_method
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=513 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=507 a=42 n=isflagset
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=516 a=17 n=if
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=513 a=26 n=save
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=516 a=3 n=exit
...

The above example is for a registration with default config for version 3.1.0, without authentication. Listed fields are: 'c' - config file; 'l' - line; 'a' - internal action id; 'n' - name of executed action. 'ERROR' prefix is printed because these messages were sent to the L_ERR log level.