package LWP::Protocol;
use base 'LWP::MemberMixin';
our $VERSION = '6.53';
use strict;
use Carp ();
use HTTP::Status ();
use HTTP::Response ();
use Try::Tiny qw(try catch);
my %ImplementedBy = (); # scheme => classname
sub new
{
my($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};
return $ic if $ic;
return '' unless $scheme =~ /^([.+\-\w]+)$/; # check valid URL schemes
$scheme = $1; # untaint
$scheme =~ tr/.+-/_/; # make it a legal module name
# scheme not yet known, look for a 'use'd implementation
$ic = "LWP::Protocol::$scheme"; # 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;
$ic;
}
sub request
{
my($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) {
$response->{default_add_content} = 1;
}
elsif (!ref($arg) && length($arg)) {
open(my $fh, ">", $arg) or die "Can't write to '$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 {
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 base 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, and you get an initialized subclass
appropriate for that access method. In other words, the
L function calls the constructor for one of its
subclasses.
All derived C classes need to override the request()
method which is used to service a request. The overridden method can
make use of the collect() function 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 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);
Dispatches a request over the protocol, and returns a response
object. This method needs to be overridden in subclasses. Refer to
L 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.
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 by returning a reference to an
empty string.
The return value is the L object reference.
B 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, $content)
Can be called when the whole response content is available as content. This
will invoke L with a collector callback that
returns a reference to C<$content> the first time and an empty string the
next.
=head1 SEE ALSO
Inspect the F and F 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