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package HTTP::Headers::Util;
use strict;
use vars qw($VERSION @ISA @EXPORT_OK);
$VERSION = sprintf("%d.%02d", q$Revision: 1.7 $ =~ /(\d+)\.(\d+)/);
require Exporter;
@ISA=qw(Exporter);
@EXPORT_OK=qw(split_header_words join_header_words);
=head1 NAME
HTTP::Headers::Util - Header value parsing utility functions
=head1 SYNOPSIS
use HTTP::Headers::Util qw(split_header_words);
@values = split_header_words($h->header("Content-Type"));
=head1 DESCRIPTION
This module provide a few functions that helps parsing and
construction of valid HTTP header values. None of the functions are
exported by default.
The following functions are provided:
=over 4
=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
know how to deal with ",", ";" and "=" as well as quoted values after
"=". A list of space separated tokens are parsed as if they were
separated by ";".
If the @header_values passed as argument contains multiple values,
then they are treated as if they were a single value separated by
comma ",".
This means that this function is useful to parse header fields that
follow this syntax (BNF as from the HTTP/1.1 specification, but we relax
the requirement for tokens).
headers = #header
header = (token | parameter) *( [";"] (token | parameter))
token = 1*<any CHAR except CTLs or separators>
separators = "(" | ")" | "<" | ">" | "@"
| "," | ";" | ":" | "\" | <">
| "/" | "[" | "]" | "?" | "="
| "{" | "}" | SP | HT
quoted-string = ( <"> *(qdtext | quoted-pair ) <"> )
qdtext = <any TEXT except <">>
quoted-pair = "\" CHAR
parameter = attribute "=" value
attribute = token
value = token | quoted-string
Each I<header> is represented by an anonymous array of key/value
pairs. If a token is recognized then the value will be C<undef>.
Syntactically incorrect headers will not necessary be parsed as you
would want.
This is easier to describe with some examples:
split_header_words('foo="bar"; port="80,81"; discard, bar=baz')
split_header_words('text/html; charset="iso-8859-1");
split_header_words('Basic realm="\"foo\\bar\""');
will return
[foo=>'bar', port=>'80,81', discard=> undef], [bar=>'baz' ]
['text/html' => undef, charset => 'iso-8859-1']
[Basic => undef, realm => '"foo\bar"']
=cut
sub split_header_words
{
my(@val) = @_;
my @res;
for (@val) {
my @cur;
while (length) {
if (s/^\s*(=*[^\s=;,]+)//) { # 'token' or parameter 'attribute'
push(@cur, $1);
# a quoted value
if (s/^\s*=\s*\"([^\"\\]*(?:\\.[^\"\\]*)*)\"//) {
my $val = $1;
$val =~ s/\\(.)/$1/g;
push(@cur, $val);
# some unquoted value
} elsif (s/^\s*=\s*([^;,\s]*)//) {
my $val = $1;
$val =~ s/\s+$//;
push(@cur, $val);
# no value, a lone token
} else {
push(@cur, undef);
}
} elsif (s/^\s*,//) {
push(@res, [@cur]) if @cur;
@cur = ();
} elsif (s/^\s*;// || s/^\s+//) {
# continue
} else {
die "This should not happen: '$_'";
}
}
push(@res, \@cur) if @cur;
}
@res;
}
=item join_header_words( @arrays )
This will do the opposite convertion of what split_header_words()
does. It takes a list of anonymous arrays as argument (or a list of
key/value pairs) and produce a single header value. Attribute values
are quoted if needed.
Example:
join_header_words(["text/plain" => undef, charset => "iso-8859/1"]);
join_header_words(""text/plain" => undef, charset => "iso-8859/1");
will both return the string:
text/plain; charset="iso-8859/1"
=cut
sub join_header_words
{
@_ = ([@_]) if @_ && !ref($_[0]);
my @res;
for (@_) {
my @cur = @$_;
my @attr;
while (@cur) {
my $k = shift @cur;
my $v = shift @cur;
if (defined $v) {
if ($v =~ /^\w+$/) {
$k .= "=$v";
} else {
$v =~ s/([\"\\])/\\$1/g; # escape " and \
$k .= qq(="$v");
}
}
push(@attr, $k);
}
push(@res, join("; ", @attr)) if @attr;
}
join(", ", @res);
}
1;
__END__
=back
=head1 COPYRIGHT
Copyright 1997-1998, Gisle Aas
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
=cut
|
