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package LWP::Protocol; require LWP::MemberMixin; @ISA = qw(LWP::MemberMixin); $VERSION = "6.00"; use strict; use Carp (); use HTTP::Status (); use HTTP::Response; my %ImplementedBy = (); # scheme => classname sub new { my($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 =~ s/[.+\-]/_/g; # 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 eval "require $ic"; if ($@) { if ($@ =~ /Can't locate/) { #' #emacs get confused by ' $ic = ''; } else { die "$@\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)}; eval { local $\; # protect the print below from surprises if (!defined($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; } } }; my $err = $@; delete $response->{handlers}{response_data}; delete $response->{handlers} unless %{$response->{handlers}}; if ($err) { chomp($err); $response->push_header('X-Died' => $err); $response->push_header("Client-Aborted", "die"); return $response; } return $response; } sub collect_once { my($self, $arg, $response) = @_; my $content = \ $_[3]; my $first = 1; $self->collect($arg, $response, sub { return $content if $first--; return \ ""; }); } 1; __END__ =head1 NAME LWP::Protocol - Base class for LWP protocols =head1 SYNOPSIS package LWP::Protocol::foo; require LWP::Protocol; @ISA=qw(LWP::Protocol); =head1 DESCRIPTION This class is used a the base class for all protocol implementations supported by the LWP library. When creating an instance of this class using C<LWP::Protocol::create($url)>, and you get an initialised subclass appropriate for that access method. In other words, the LWP::Protocol::create() function calls the constructor for one of its subclasses. All derived LWP::Protocol 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. The following methods and functions are provided: =over 4 =item $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. =item $prot = LWP::Protocol::create($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. =item $class = LWP::Protocol::implementor($scheme, [$class]) Get and/or set implementor class for a scheme. Returns '' if the specified scheme is not supported. =item $prot->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<LWP::UserAgent> for description of the arguments. =item $prot->collect($arg, $response, $collector) Called to collect the content of a request, and process it appropriately into a scalar, file, or by calling a callback. If $arg is undefined, then the content is stored within the $response. If $arg is a simple scalar, then $arg is interpreted as a file name and the content is written to this file. If $arg is a reference to a routine, 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 $collector signals EOF by returning a reference to an empty sting. The return value from collect() is the $response object reference. B<Note:> We will only use the callback or file argument if $response->is_success(). This avoids sending content data for redirects and authentication responses to the callback which would be confusing. =item $prot->collect_once($arg, $response, $content) Can be called when the whole response content is available as $content. This will invoke collect() with a collector callback that returns a reference to $content the first time and an empty string the next. =back =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.