[sr-dev] [ser-dev] re.h - subst_str ussage

Sun Mar 29 17:20:43 CEST 2015

Hi, I am trying to use Kamailio specific function 'subst_str' for replacing
some media attributes in SDP in my module.

Finally I have resolved how to create 'subst_expr' structure so I can pass
it to 'subst_str' function. I am doing something like this:

      struct subst_expr *seMedia;

      char *pattern;      asprintf(&pattern, "/m=audio
([0-9]{0,5})/m=audio %s/", _host_port.s);

      str *subst;
      subst = (str *) pkg_malloc(sizeof(str));
      subst->s = pattern;
      subst->len = strlen(pattern);

      seMedia = subst_parser(subst);

      int count = 0;
      str *tmpBody;
      char const *oldBody = (char const *) msg->body;
      tmpBody = subst_str(oldBody, msg, seMedia, &count);

      if (count > 0) {

// do other stuff

I am trying to replace all "m=audio {port number}" attributes with port
5060. I think that the regular expression is correct. But unfortunately in
Kamailio log I am getting something like this:

 0(25049) DEBUG: <core> [re.c:329]: subst_parser(): subst_parser: ok, se is
0xb72941d8
 0(25049) DEBUG: <core> [re.c:454]: subst_run(): subst_run: running. r=1
 0(25049) DEBUG: <core> [re.c:523]: subst_str(): subst_str: no match

It seems like regex was not matched but after this I am printing out whole
message and I can see that in SDP 'm=audio' is present. I also noticed
another thing when I am printing out 'seMedia->replacement.s' in log I am
getting my replacement "m=audio 5060" but also at the end of the string I
can see some weird character:

[image: Inline image 1]

If someone came across this issue in the past and resolved it, it would be
great if he/she can share his/her knowledge with me because seriously this
issue is driving me crazy.

On Thu, Mar 12, 2015 at 9:17 PM, Cockhootec Yahrabee <cockootec at gmail.com>
wrote:

> Thanks a lot. I am sorry I didn't code with pointers quite a long time so
> I need to refresh my knowledge a bit :)
> But unfortunately it was not the main problem.
>
> In Kamailio log I am getting something like this:
>
>  0(17809) ERROR: <core> [re.c:181]: parse_repl(): subst_parser: bad
> specifier in replace part /$1 5060/gm
>
> I think, that problem is on this line
> https://gist.github.com/ivanbarlog/1b552b57e89bf4670872#file-test-c-L5
> where I am trying to use $1 as a placeholder for first matched group.
>
> I also tried it without it - just replace `m=audio` (not m=*) but it also
> didn't worked.
>
> I am also not sure if I am correctly re-transmitting updated SIP message.
> I looked at other modules which perform the same action and I tried to
> inspire with their code but unfortunately it's not working.
>
> Could you please review this code sample
> https://gist.github.com/ivanbarlog/4040ae5b735386a88ea0 ?
>
> Or maybe if you can point me to some resource where I can read more about
> it. Also it would be great if there was some tutorial for developing
> modules.
>
> Thanks for help
>
>
> On Wed, Mar 11, 2015 at 7:20 PM, Daniel-Constantin Mierla <
> miconda at gmail.com> wrote:
>
>>  Hello,
>>
>> at least one problem is the next line in your code:
>>
>> subst->len = sizeof(pattern);
>>
>> should be:
>>
>> subst->len = strlen(pattern);
>>
>> Because patter is declared as 'char*', sizeof returns 4 or 8 (if 32b or
>> 64b architecture).
>>
>> Try with that change and see how far it goes.
>>
>> Cheers,
>> Daniel
>>
>>
>> On 11/03/15 00:43, Cockhootec Yahrabee wrote:
>>
>> Hi guys,
>> I am trying to 'search&replace' some patterns in message body but
>> unfortunately with no result (but bunch of errors).
>>
>>  First of all I am trying to perform regex substitution as one that can
>> be seen at https://regex101.com/r/vF1kZ7/1
>>
>>  Since I have regular expression I am trying to convert it so it will
>> work with `sub_str` function from re.h
>>
>>  Here is my attempt:
>> https://gist.github.com/ivanbarlog/1b552b57e89bf4670872#file-test-c-L12
>>
>>  I had quite lot of errors but last error I am getting is that
>> `subst_parser` cannot find separator
>> https://github.com/kamailio/kamailio/blob/master/re.c#L240
>>
>>  Since the `struct subst_expr` is not parsed right the next error is
>> segfault in `subst_str` function.
>>
>>
>>
>>  If someone can explain me how exactly I should use `subst_str` function
>> with my regex I'll be really grateful. Little example code would be also
>> great.
>>
>>  Thanks in advance
>>
>>
>> _______________________________________________
>> sr-dev mailing listsr-dev at lists.sip-router.orghttp://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev
>>
>>
>> --
>> Daniel-Constantin Mierlahttp://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
>> Kamailio World Conference, May 27-29, 2015
>> Berlin, Germany - http://www.kamailioworld.com
>>
>>
>
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