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kamailio/doc/tutorials/serdev/from_parser.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<section id="from_parser" xmlns:xi="http://www.w3.org/2001/XInclude">
<sectioninfo>
<revhistory>
<revision>
<revnumber>$Revision$</revnumber>
<date>$Date$</date>
</revision>
</revhistory>
</sectioninfo>
<title>From Header Field Parser</title>
<para>
This parser is only a wrapper to the To header field parser. Since
bodies of both header fields are identical, From parser only calls To
parser.
</para>
<para>
The wrapper can be found in file <filename>parse_from.c</filename>
under <filename>parser</filename> subdirectory. There is only one
function called <function>parse_from_header</function>. The function
accepts one parameter which is pointer to structure representing the
From header field to be parsed. The function creates an instance of
<structname>to_body</structname> structure and initializes it. It then
calls <function>parse_to</function> function and if everything went OK,
the pointer to the newly created structure will be put in
<structfield>parsed</structfield> field of the structure representing
the parsed header field.
</para>
<para>
The newly created structure will be freed when the whole message is
being destroyed. (See To header field parser description for more
details).
</para>
<para>
From parser <emphasis>must be called explicitly</emphasis> !
</para>
<para>
If the main parser finds a From header field, it will not parse the
header field body automatically. It is up to you to call the
<function>parse_from_header</function> when you want to parse a From
header field body.
</para>
</section>