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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="cseq_parser" xmlns:xi="http://www.w3.org/2001/XInclude">
<sectioninfo>
<revhistory>
<revision>
<revnumber>$Revision$</revnumber>
<date>$Date$</date>
</revision>
</revhistory>
</sectioninfo>
<title>CSeq Header Field Parser</title>
<para>
Purpose of this parser is to parse body of CSeq header field. The
parser can be found in file <filename>parse_cseq.c</filename> under
<filename>parser</filename> subdirectory.
</para>
<para>
Main function is <function>parse_cseq</function> but there is no need
to call the function explicitly. Every time the parser finds a CSeq
header field, this function will be called automatically. Result of the
parser is <structname>cseq_body</structname> structure. Pointer to the
structure will be stored in <structfield>parsed</structfield> field of
<structname>hdr_field</structname> structure. Since the pointer is
<type>void*</type>, there is a convenience macro
<function>get_cseq</function> in file <filename>parse_cseq.h</filename>
that will do the necessary type-casting and will return pointer to
<structname>cseq_body</structname> structure.
</para>
<para>
The parser will parse CSeq body according to the grammar defined in
<acronym>RFC3261</acronym> and store result in
<structname>cseq_body</structname> structure.
</para>
<para>
The parser gets called automatically from function
<function>get_hdr_field</function> in file
<filename>msg_parser.c</filename>. The function first creates and
initializes an instance of <structname>cseq_body</structname>
structure, then calls <function>parse_cseq</function> function with the
structure as a parameter and if everything went OK, puts the pointer to
the structure in <structfield>parsed</structfield> field of
<structname>hdr_field</structname> structure representing the parsed
CSeq header field.
</para>
<para>
The newly created structure will be freed when the message is being
destroyed, see function <function>clean_hdr_field</function> in file
<filename>hf.c</filename> for more details.
</para>
<para>
See <xref linkend="cseq_body"/> for description of the
<structname>cseq_body</structname> structure.
</para>
</section>
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