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_level_name (str)
              3.5. log_facility (str)
              3.6. log_prefix (str)
              3.7. step_usleep (int)
              3.8. step_loops (int)
              3.9. mod_hash_size (int)
              3.10. mod_level_mode (int)
              3.11. mod_level (str)
              3.12. log_assign (int)
              3.13. cfgpkgcheck (int)
              3.14. reset_msgid (int)

        4. Functions

              4.1. dbg_breakpoint(mode)
              4.2. dbg_pv_dump([mask] [, level])

        5. Exported RPC Functions

              5.1. dbg.ls
              5.2. dbg.trace
              5.3. dbg.bp
              5.4. dbg.mod_level
              5.5. dbg.reset_msgid

        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_level_name parameter
   1.5. Set log_facility parameter
   1.6. Set log_prefix parameter
   1.7. Set step_usleep parameter
   1.8. Set step_loops parameter
   1.9. Set mod_hash_size parameter
   1.10. Set mod_level_mode parameter
   1.11. Set mod_level parameter
   1.12. Set log_assign parameter
   1.13. Set cfgpkgcheck parameter
   1.14. Set reset_msgid parameter
   1.15. dbg_breakpoint usage
   1.16. dbg_pv_dump 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_level_name (str)
        3.5. log_facility (str)
        3.6. log_prefix (str)
        3.7. step_usleep (int)
        3.8. step_loops (int)
        3.9. mod_hash_size (int)
        3.10. mod_level_mode (int)
        3.11. mod_level (str)
        3.12. log_assign (int)
        3.13. cfgpkgcheck (int)
        3.14. reset_msgid (int)

   4. Functions

        4.1. dbg_breakpoint(mode)
        4.2. dbg_pv_dump([mask] [, level])

   5. Exported RPC Functions

        5.1. dbg.ls
        5.2. dbg.trace
        5.3. dbg.bp
        5.4. dbg.mod_level
        5.5. dbg.reset_msgid

   6. Usage

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
   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_level_name (str)
   3.5. log_facility (str)
   3.6. log_prefix (str)
   3.7. step_usleep (int)
   3.8. step_loops (int)
   3.9. mod_hash_size (int)
   3.10. mod_level_mode (int)
   3.11. mod_level (str)
   3.12. log_assign (int)
   3.13. cfgpkgcheck (int)
   3.14. reset_msgid (int)

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_level_name (str)

   What log level name is to be used to print cfg trace messages.

   Default value is “NULL” (use default log names).

   Example 1.4. Set log_level_name parameter
...
modparam("debugger", "log_level_name", "exec")
...

3.5. 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 1.5. Set log_facility parameter
...
modparam("debugger", "log_facility", "LOG_DAEMON")
...

3.6. log_prefix (str)

   String to print before any module-specific messages.

   Default value is “*** cfgtrace:”.

   Example 1.6. Set log_prefix parameter
...
modparam("debugger", "log_prefix", "from-debugger-with-love:")
...

3.7. 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 1.7. Set step_usleep parameter
...
modparam("debugger", "step_usleep", 500000)
...

3.8. 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 1.8. Set step_loops parameter
...
modparam("debugger", "step_loops", 100)
...

3.9. mod_hash_size (int)

   Used to compute power of two as size of internal hash table to store
   levels per module (e.g., if its set to 4, internal hash table has 16
   slots). This parameter is accesible readonly via the Kamailio config
   framework.

   Default value is “0” - feature disabled.

   Example 1.9. Set mod_hash_size parameter
...
modparam("debugger", "mod_hash_size", 5)
...

3.10. mod_level_mode (int)

   Enable or disable per module log level (0 - disabled, 1 - enabled).
   This parameter is tunable via the Kamailio config framework. To use per
   module log level you also have to set mod_hash_size.

   Default value is “0”.

   Example 1.10. Set mod_level_mode parameter
...
modparam("debugger", "mod_level_mode", 1)
...

3.11. mod_level (str)

   Specify module log level - the value must be in the format:
   modulename=level. The parameter can be set many times. For core log
   level, use module name 'core'. You also must enable mod_level_mode and
   mod_hash_size.

   Example 1.11. Set mod_level parameter
...
modparam("debugger", "mod_level", "core=3")
modparam("debugger", "mod_level", "tm=3")
...

3.12. log_assign (int)

   Enable or disable log assign actions on config (0 - disabled, 1 -
   enabled).

   Default value is “0”.

   Example 1.12. Set log_assign parameter
...
modparam("debugger", "log_assign", 1)
...

3.13. cfgpkgcheck (int)

   If set, before each config action is done pkg memory check, useful to
   detect buffer overflows.

   Default value is “0” (disabled).

   Example 1.13. Set cfgpkgcheck parameter
...
modparam("debugger", "cfgpkgcheck", 1)
...

3.14. reset_msgid (int)

   Used to enable or disable the ability to reset the msgid ($mi) through
   the dbg.reset_msgid RPC command. (0 - disabled, 1 - enabled).

   Default value is “0” - feature disabled.

   Example 1.14. Set reset_msgid parameter
...
modparam("debugger", "reset_msgid", 1)
...

4. Functions

   4.1. dbg_breakpoint(mode)
   4.2. dbg_pv_dump([mask] [, level])

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

4.2.  dbg_pv_dump([mask] [, level])

   Prints the content of pv_cache on json format. Defaults are mask=31 and
   level = "L_DBG"

   mask - Controls the content to dump:
     * 1 - dump null values
     * 2 - dump avp vars
     * 4 - dump script vars
     * 8 - dump xavp vars
     * 16 - dump DP_OTHER vars

   level - The level that will be used in LOG function. It can be:
     * L_ALERT - log level -5
     * L_BUG - log level -4
     * L_CRIT - log level -3
     * L_ERR - log level -1
     * L_WARN - log level 0
     * L_NOTICE - log level 1
     * L_INFO - log level 2
     * L_DBG - log level 3

   Example 1.16. dbg_pv_dump usage
...
$var(temp) = 1;
$avp(s:more_avp) = 2;
$avp(s:more_avp) = 3;
$xavp(x=>more) = "bye";
$xavp(x[0]=>more) = "hi";
$xavp(x[0]=>other) = 1;
$xavp(x[0]=>other) = 2;
$xavp(x=>different) = "foo";
$var(empty) = $null;

dbg_pv_dump(30, "L_DBG");
...

   Output
...
 4(30943) DEBUG: debugger [debugger_api.c:1613]: dbg_dump_json(): {"$sp":37597,"
$var(rc)":0,"$var(temp)":1,"$avp(more_avp)":[3,2],"$si":"127.0.0.1","$rc":0,"$xa
vp(x)":[{"different":["foo"]},{"other":[2,1],"more":["hi","bye"]}],"$T_branch_id
x":0,"$var(empty)":0}
 ...

5. Exported RPC Functions

   5.1. dbg.ls
   5.2. dbg.trace
   5.3. dbg.bp
   5.4. dbg.mod_level
   5.5. dbg.reset_msgid

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

5.4.  dbg.mod_level

   Specify module log level.

   Name: dbg.mod_level

   Parameters:
     * _module_ : For core log level, use module name 'core'
     * _level_ : integer

   Examples of use with kamcmd:
                dbg.mod_level core 3
                dbg.mod_level tm 3

5.5.  dbg.reset_msgid

   Resets the message sequence ($mi). Internally there is no real change.
   This can be useful for unit test cases in order to be able to replicate
   exactly the same kamailio output. You need to set the debugger
   parameter reset_msgid to 1 to activate this functionallity.

   Name: dbg.reset_msgid

   Examples of use with kamcmd:
                dbg.reset_msgid

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_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 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.
