debugger Module

Daniel-Constantin Mierla

   asipto.com

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2010 Daniel-Constantin Mierla (asipto.com)
     __________________________________________________________________

   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

   Table of Contents

   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

1. Overview

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

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

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

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)
   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)

3.1. cfgtrace (int)

   Control whether config running 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)

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

   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
   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 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)

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 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
   5.2. dbg.trace
   5.3. dbg.bp

5.1.  dbg.ls

   List SIP router 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 sercmd:
                dbg.ls
                dbg.ls 1234

5.2.  dbg.trace

   Control config running trace.

   Name: dbg.trace

   Parameters:
     * _cmd_ : inner 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 it will print details for all processes.

   Examples for using with sercmd:
                dbg.trace on
                dbg.trace off
                dbg.trace on 1234

5.3.  dbg.bp

   Control breakpoints and config execution.

   Name: dbg.bp

   Parameters:
     * _cmd_ : inner command, see next section for the list of available
       values.
     * _pid_ : pid for which to apply the inner command. If 'pid' is
       omitted, then the inner command will be applied to all processes.
     * _params_ : extra params specific for each inner command.

   Inner 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 - eval a pseudo-variable and print the result in RPC Pid
       parameter is mandatory.
     * log - eval a pseudo-variable and print the result in SIP router
       logs. Pid parameter is mandatory.

   Examples for using with sercmd:
                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 config file step-by-step for a particular
   SIP message.

   You need to connect using sercmd (or other RPC client) to SIP Router.
   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 SIP router
   processes in no-breakpoint mode so they can process other SIP messages
   without need to interact with them.

   The process blocked at 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 retrive the value of PV. Once you
   are done and want to continue the execution of the config wihtout
   interaction use 'dbg.bp move pid'.

   Here is an example of session:
...
sercmd> 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
}

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

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

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

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

sercmd> 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_pro
cess_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_to
tag
 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_met
hod
 9(6285) ERROR: *** cfgtrace: c=[/etc/kamailio/debugger.cfg] l=386 a=25 n=t_chec
k_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_met
hod
 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_met
hod
 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_met
hod
 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_met
hod
 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=isflag
set
 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 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.
