package LWP::Protocol;
use parent 'LWP::MemberMixin';
our $VERSION = '6.76';
use strict;
use Carp ();
use HTTP::Status ();
use HTTP::Response ();
use Scalar::Util qw(openhandle);
use Try::Tiny qw(try catch);
my %ImplementedBy = (); # scheme => classname
my %ImplementorAlreadyTested;
sub new
{
my($class, $scheme, $ua) = @_;
my $self = bless {
scheme => $scheme,
ua => $ua,
# historical/redundant
max_size => $ua->{max_size},
}, $class;
$self;
}
sub create
{
my($scheme, $ua) = @_;
my $impclass = LWP::Protocol::implementor($scheme) or
Carp::croak("Protocol scheme '$scheme' is not supported");
# hand-off to scheme specific implementation sub-class
my $protocol = $impclass->new($scheme, $ua);
return $protocol;
}
sub implementor
{
my($scheme, $impclass) = @_;
if ($impclass) {
$ImplementedBy{$scheme} = $impclass;
}
my $ic = $ImplementedBy{$scheme};
# module does not exist
return $ic if $ic || $ImplementorAlreadyTested{$scheme};
return '' unless $scheme =~ /^([.+\-\w]+)$/; # check valid URL schemes
$scheme = $1; # untaint
# scheme not yet known, look for a 'use'd implementation
$ic = $scheme;
$ic =~ tr/.+-/_/; # make it a legal module name
$ic = "LWP::Protocol::$ic"; # default location
$ic = "LWP::Protocol::nntp" if $scheme eq 'news'; #XXX ugly hack
no strict 'refs';
# check we actually have one for the scheme:
unless (@{"${ic}::ISA"}) {
# try to autoload it
try {
(my $class = $ic) =~ s{::}{/}g;
$class .= '.pm' unless $class =~ /\.pm$/;
require $class;
}
catch {
my $error = $_;
if ($error =~ /Can't locate/) {
$ic = '';
}
else {
die "$error\n";
}
};
}
$ImplementedBy{$scheme} = $ic if $ic;
$ImplementorAlreadyTested{$scheme} = 1;
$ic;
}
sub request
{
my($self, $request, $proxy, $arg, $size, $timeout) = @_;
Carp::croak('LWP::Protocol::request() needs to be overridden in subclasses');
}
# legacy
sub timeout { shift->_elem('timeout', @_); }
sub max_size { shift->_elem('max_size', @_); }
sub collect
{
my ($self, $arg, $response, $collector) = @_;
my $content;
my($ua, $max_size) = @{$self}{qw(ua max_size)};
# This can't be moved to Try::Tiny due to the closures within causing
# leaks on any version of Perl prior to 5.18.
# https://perl5.git.perl.org/perl.git/commitdiff/a0d2bbd5c
my $error = do { #catch
local $@;
local $\; # protect the print below from surprises
eval { # try
if (!defined($arg) || !$response->is_success) {
$response->{default_add_content} = 1;
}
elsif (defined(openhandle($arg)) || !ref($arg) && length($arg)) {
my $existing_fh = defined(openhandle($arg));
my $mode = $existing_fh ? '>&=' : '>';
open(my $fh, $mode, $arg) or die "Can't write to '$arg': $!";
binmode($fh);
push(@{$response->{handlers}{response_data}}, {
callback => sub {
print $fh $_[3] or die "Can't write to '$arg': $!";
1;
},
});
push(@{$response->{handlers}{response_done}}, {
callback => sub {
unless ($existing_fh) {
close($fh) or die "Can't write to '$arg': $!";
}
undef($fh);
},
});
}
elsif (ref($arg) eq 'CODE') {
push(@{$response->{handlers}{response_data}}, {
callback => sub {
&$arg($_[3], $_[0], $self);
1;
},
});
}
else {
die "Unexpected collect argument '$arg'";
}
$ua->run_handlers("response_header", $response);
if (delete $response->{default_add_content}) {
push(@{$response->{handlers}{response_data}}, {
callback => sub {
$_[0]->add_content($_[3]);
1;
},
});
}
my $content_size = 0;
my $length = $response->content_length;
my %skip_h;
while ($content = &$collector, length $$content) {
for my $h ($ua->handlers("response_data", $response)) {
next if $skip_h{$h};
unless ($h->{callback}->($response, $ua, $h, $$content)) {
# XXX remove from $response->{handlers}{response_data} if present
$skip_h{$h}++;
}
}
$content_size += length($$content);
$ua->progress(($length ? ($content_size / $length) : "tick"), $response);
if (defined($max_size) && $content_size > $max_size) {
$response->push_header("Client-Aborted", "max_size");
last;
}
}
1;
};
$@;
};
if ($error) {
chomp($error);
$response->push_header('X-Died' => $error);
$response->push_header("Client-Aborted", "die");
};
delete $response->{handlers}{response_data};
delete $response->{handlers} unless %{$response->{handlers}};
return $response;
}
sub collect_once
{
my($self, $arg, $response) = @_;
my $content = \ $_[3];
my $first = 1;
$self->collect($arg, $response, sub {
return $content if $first--;
return \ "";
});
}
1;
__END__
=pod
=head1 NAME
LWP::Protocol - Base class for LWP protocols
=head1 SYNOPSIS
package LWP::Protocol::foo;
use parent qw(LWP::Protocol);
=head1 DESCRIPTION
This class is used as the base class for all protocol implementations
supported by the LWP library.
When creating an instance of this class using
C<LWP::Protocol::create($url)>, and you get an initialized subclass
appropriate for that access method. In other words, the
L<LWP::Protocol/create> function calls the constructor for one of its
subclasses.
All derived C<LWP::Protocol> classes need to override the C<request()>
method which is used to service a request. The overridden method can
make use of the C<collect()> method to collect together chunks of data
as it is received.
=head1 METHODS
The following methods and functions are provided:
=head2 new
my $prot = LWP::Protocol->new();
The LWP::Protocol constructor is inherited by subclasses. As this is a
virtual base class this method should B<not> be called directly.
=head2 create
my $prot = LWP::Protocol::create($scheme)
Create an object of the class implementing the protocol to handle the
given scheme. This is a function, not a method. It is more an object
factory than a constructor. This is the function user agents should
use to access protocols.
=head2 implementor
my $class = LWP::Protocol::implementor($scheme, [$class])
Get and/or set implementor class for a scheme. Returns C<''> if the
specified scheme is not supported.
=head2 request
$response = $protocol->request($request, $proxy, undef);
$response = $protocol->request($request, $proxy, '/tmp/sss');
$response = $protocol->request($request, $proxy, \&callback, 1024);
$response = $protocol->request($request, $proxy, $fh);
Dispatches a request over the protocol, and returns a response
object. This method needs to be overridden in subclasses. Refer to
L<LWP::UserAgent> for description of the arguments.
=head2 collect
my $res = $prot->collect(undef, $response, $collector); # stored in $response
my $res = $prot->collect($filename, $response, $collector);
my $res = $prot->collect(sub { ... }, $response, $collector);
Collect the content of a request, and process it appropriately into a scalar,
file, or by calling a callback. If the first parameter is undefined, then the
content is stored within the C<$response>. If it's a simple scalar, then it's
interpreted as a file name and the content is written to this file. If it's a
code reference, then content is passed to this routine.
If it is a filehandle, or similar, such as a L<File::Temp> object,
content will be written to it.
The collector is a routine that will be called and which is
responsible for returning pieces (as ref to scalar) of the content to
process. The C<$collector> signals C<EOF> by returning a reference to an
empty string.
The return value is the L<HTTP::Response> object reference.
B<Note:> We will only use the callback or file argument if
C<< $response->is_success() >>. This avoids sending content data for
redirects and authentication responses to the callback which would be
confusing.
=head2 collect_once
$prot->collect_once($arg, $response, $content)
Can be called when the whole response content is available as content. This
will invoke L<LWP::Protocol/collect> with a collector callback that
returns a reference to C<$content> the first time and an empty string the
next.
=head1 SEE ALSO
Inspect the F<LWP/Protocol/file.pm> and F<LWP/Protocol/http.pm> files
for examples of usage.
=head1 COPYRIGHT
Copyright 1995-2001 Gisle Aas.
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
=cut
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