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.\" ========================================================================
.\"
.IX Title "HTTP::Headers::Util 3"
.TH HTTP::Headers::Util 3 "2018-06-05" "perl v5.16.3" "User Contributed Perl Documentation"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.SH "NAME"
HTTP::Headers::Util \- Header value parsing utility functions
.SH "VERSION"
.IX Header "VERSION"
version 6.18
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& use HTTP::Headers::Util qw(split_header_words);
\& @values = split_header_words($h\->header("Content\-Type"));
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module provides a few functions that helps parsing and
construction of valid \s-1HTTP\s0 header values. None of the functions are
exported by default.
.PP
The following functions are available:
.ie n .IP "split_header_words( @header_values )" 4
.el .IP "split_header_words( \f(CW@header_values\fR )" 4
.IX Item "split_header_words( @header_values )"
This function will parse the header values given as argument into a
list of anonymous arrays containing key/value pairs. The function
knows how to deal with \*(L",\*(R", \*(L";\*(R" and \*(L"=\*(R" as well as quoted values after
\&\*(L"=\*(R". A list of space separated tokens are parsed as if they were
separated by \*(L";\*(R".
.Sp
If the \f(CW@header_values\fR passed as argument contains multiple values,
then they are treated as if they were a single value separated by
comma \*(L",\*(R".
.Sp
This means that this function is useful for parsing header fields that
follow this syntax (\s-1BNF\s0 as from the \s-1HTTP/1.1\s0 specification, but we relax
the requirement for tokens).
.Sp
.Vb 2
\& headers = #header
\& header = (token | parameter) *( [";"] (token | parameter))
\&
\& token = 1*<any CHAR except CTLs or separators>
\& separators = "(" | ")" | "<" | ">" | "@"
\& | "," | ";" | ":" | "\e" | <">
\& | "/" | "[" | "]" | "?" | "="
\& | "{" | "}" | SP | HT
\&
\& quoted\-string = ( <"> *(qdtext | quoted\-pair ) <"> )
\& qdtext = <any TEXT except <">>
\& quoted\-pair = "\e" CHAR
\&
\& parameter = attribute "=" value
\& attribute = token
\& value = token | quoted\-string
.Ve
.Sp
Each \fIheader\fR is represented by an anonymous array of key/value
pairs. The keys will be all be forced to lower case.
The value for a simple token (not part of a parameter) is \f(CW\*(C`undef\*(C'\fR.
Syntactically incorrect headers will not necessarily be parsed as you
would want.
.Sp
This is easier to describe with some examples:
.Sp
.Vb 3
\& split_header_words(\*(Aqfoo="bar"; port="80,81"; DISCARD, BAR=baz\*(Aq);
\& split_header_words(\*(Aqtext/html; charset="iso\-8859\-1"\*(Aq);
\& split_header_words(\*(AqBasic realm="\e\e"foo\e\e\e\ebar\e\e""\*(Aq);
.Ve
.Sp
will return
.Sp
.Vb 3
\& [foo=>\*(Aqbar\*(Aq, port=>\*(Aq80,81\*(Aq, discard=> undef], [bar=>\*(Aqbaz\*(Aq ]
\& [\*(Aqtext/html\*(Aq => undef, charset => \*(Aqiso\-8859\-1\*(Aq]
\& [basic => undef, realm => "\e"foo\e\ebar\e""]
.Ve
.Sp
If you don't want the function to convert tokens and attribute keys to
lower case you can call it as \f(CW\*(C`_split_header_words\*(C'\fR instead (with a
leading underscore).
.ie n .IP "join_header_words( @arrays )" 4
.el .IP "join_header_words( \f(CW@arrays\fR )" 4
.IX Item "join_header_words( @arrays )"
This will do the opposite of the conversion done by \fIsplit_header_words()\fR.
It takes a list of anonymous arrays as arguments (or a list of
key/value pairs) and produces a single header value. Attribute values
are quoted if needed.
.Sp
Example:
.Sp
.Vb 2
\& join_header_words(["text/plain" => undef, charset => "iso\-8859/1"]);
\& join_header_words("text/plain" => undef, charset => "iso\-8859/1");
.Ve
.Sp
will both return the string:
.Sp
.Vb 1
\& text/plain; charset="iso\-8859/1"
.Ve
.SH "AUTHOR"
.IX Header "AUTHOR"
Gisle Aas <gisle@activestate.com>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 1994\-2017 by Gisle Aas.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.