## $Id: Response.pm,v 1.36 2001/11/15 06:42:40 gisle Exp $package HTTP::Response;=head1 NAMEHTTP::Response - Class encapsulating HTTP Responses=head1 SYNOPSIS require HTTP::Response;=head1 DESCRIPTIONThe C<HTTP::Response> class encapsulates HTTP style responses.  Aresponse consists of a response line, some headers, and (potentiallyempty) content. Note that the LWP library also uses HTTP styleresponses for non-HTTP protocol schemes.Instances of this class are usually created and returned by theC<request()> method of an C<LWP::UserAgent> object: #... $response = $ua->request($request) if ($response->is_success) {     print $response->content; } else {     print $response->error_as_HTML; }C<HTTP::Response> is a subclass of C<HTTP::Message> and thereforeinherits its methods.  The inherited methods most often used are header(),push_header(), remove_header(), and content().The header convenience methods are also available.  SeeL<HTTP::Message> for details.The following additional methods are available:=over 4=cutrequire HTTP::Message;@ISA = qw(HTTP::Message);$VERSION = sprintf("%d.%02d", q$Revision: 1.36 $ =~ /(\d+)\.(\d+)/);use HTTP::Status ();use strict;=item $r = HTTP::Response->new($rc, [$msg, [$header, [$content]]])Constructs a new C<HTTP::Response> object describing a response withresponse code C<$rc> and optional message C<$msg>.  The message is ashort human readable single line string that explains the responsecode.=cutsub new{    my($class, $rc, $msg, $header, $content) = @_;    my $self = $class->SUPER::new($header, $content);    $self->code($rc);    $self->message($msg);    $self;}sub clone{    my $self = shift;    my $clone = bless $self->SUPER::clone, ref($self);    $clone->code($self->code);    $clone->message($self->message);    $clone->request($self->request->clone) if $self->request;    # we don't clone previous    $clone;}=item $r->code([$code])=item $r->message([$message])=item $r->request([$request])=item $r->previous([$previousResponse])These methods provide public access to the object attributes.  Thefirst two contain respectively the response code and the messageof the response.The request attribute is a reference the request that caused thisresponse.  It does not have to be the same request as passed to the$ua->request() method, because there might have been redirects andauthorization retries in between.The previous attribute is used to link together chains of responses.You get chains of responses if the first response is redirect orunauthorized.=cutsub code      { shift->_elem('_rc',      @_); }sub message   { shift->_elem('_msg',     @_); }sub previous  { shift->_elem('_previous',@_); }sub request   { shift->_elem('_request', @_); }=item $r->status_lineReturns the string "E<lt>code> E<lt>message>".  If the message attributeis not set then the official name of E<lt>code> (see L<HTTP::Status>)is substituted.=cutsub status_line{    my $self = shift;    my $code = $self->{'_rc'}  || "000";    my $mess = $self->{'_msg'} || HTTP::Status::status_message($code) || "?";    return "$code $mess";}=item $r->baseReturns the base URI for this response.  The return value will be areference to a URI object.The base URI is obtained from one the following sources (in priorityorder):=over 4=item 1.Embedded in the document content, for instance <BASE HREF="...">in HTML documents.=item 2.A "Content-Base:" or a "Content-Location:" header in the response.For backwards compatability with older HTTP implementations we willalso look for the "Base:" header.=item 3.The URI used to request this response. This might not be the originalURI that was passed to $ua->request() method, because we might havereceived some redirect responses first.=backWhen the LWP protocol modules produce the HTTP::Response object, thenany base URI embedded in the document (step 1) will already haveinitialized the "Content-Base:" header. This means that this methodonly performs the last 2 steps (the content is not always availableeither).=cutsub base{    my $self = shift;    my $base = $self->header('Content-Base')     ||  # used to be HTTP/1.1               $self->header('Content-Location') ||  # HTTP/1.1               $self->header('Base');                # HTTP/1.0    return $HTTP::URI_CLASS->new_abs($base, $self->request->uri);    # So yes, if $base is undef, the return value is effectively    # just a copy of $self->request->uri.}=item $r->as_stringReturns a textual representation of the response.  Mainlyuseful for debugging purposes. It takes no arguments.=cutsub as_string{    require HTTP::Status;    my $self = shift;    my @result;    #push(@result, "---- $self ----");    my $code = $self->code;    my $status_message = HTTP::Status::status_message($code) || "Unknown code";    my $message = $self->message || "";    my $status_line = "$code";    my $proto = $self->protocol;    $status_line = "$proto $status_line" if $proto;    $status_line .= " ($status_message)" if $status_message ne $message;    $status_line .= " $message";    push(@result, $status_line);    push(@result, $self->headers_as_string);    my $content = $self->content;    if (defined $content) {	push(@result, $content);    }    #push(@result, ("-" x 40));    join("\n", @result, "");}=item $r->is_info=item $r->is_success=item $r->is_redirect=item $r->is_errorThese methods indicate if the response was informational, sucessful, aredirection, or an error.=cutsub is_info     { HTTP::Status::is_info     (shift->{'_rc'}); }sub is_success  { HTTP::Status::is_success  (shift->{'_rc'}); }sub is_redirect { HTTP::Status::is_redirect (shift->{'_rc'}); }sub is_error    { HTTP::Status::is_error    (shift->{'_rc'}); }=item $r->error_as_HTML()Returns a string containing a complete HTML document indicating whaterror occurred.  This method should only be called when $r->is_erroris TRUE.=cutsub error_as_HTML{    my $self = shift;    my $title = 'An Error Occurred';    my $body  = $self->status_line;    return <<EOM;<HTML><HEAD><TITLE>$title</TITLE></HEAD><BODY><H1>$title</H1>$body</BODY></HTML>EOM}=item $r->current_ageCalculates the "current age" of the response asspecified by E<lt>draft-ietf-http-v11-spec-07> section 13.2.3.  Theage of a response is the time since it was sent by the origin server.The returned value is a number representing the age in seconds.=cutsub current_age{    my $self = shift;    # Implementation of <draft-ietf-http-v11-spec-07> section 13.2.3    # (age calculations)    my $response_time = $self->client_date;    my $date = $self->date;    my $age = 0;    if ($response_time && $date) {	$age = $response_time - $date;  # apparent_age	$age = 0 if $age < 0;    }    my $age_v = $self->header('Age');    if ($age_v && $age_v > $age) {	$age = $age_v;   # corrected_received_age    }    my $request = $self->request;    if ($request) {	my $request_time = $request->date;	if ($request_time) {	    # Add response_delay to age to get 'corrected_initial_age'	    $age += $response_time - $request_time;	}    }    if ($response_time) {	$age += time - $response_time;    }    return $age;}=item $r->freshness_lifetimeCalculates the "freshness lifetime" of the responseas specified by E<lt>draft-ietf-http-v11-spec-07> section 13.2.4.  The"freshness lifetime" is the length of time between the generation of aresponse and its expiration time.  The returned value is a numberrepresenting the freshness lifetime in seconds.If the response does not contain an "Expires" or a "Cache-Control"header, then this function will apply some simple heuristic based on'Last-Modified' to determine a suitable lifetime.=cutsub freshness_lifetime{    my $self = shift;    # First look for the Cache-Control: max-age=n header    my @cc = $self->header('Cache-Control');    if (@cc) {	my $cc;	for $cc (@cc) {	    my $cc_dir;	    for $cc_dir (split(/\s*,\s*/, $cc)) {		if ($cc_dir =~ /max-age\s*=\s*(\d+)/i) {		    return $1;		}	    }	}    }    # Next possibility is to look at the "Expires" header    my $date = $self->date || $self->client_date || time;          my $expires = $self->expires;    unless ($expires) {	# Must apply heuristic expiration	my $last_modified = $self->last_modified;	if ($last_modified) {	    my $h_exp = ($date - $last_modified) * 0.10;  # 10% since last-mod	    if ($h_exp < 60) {		return 60;  # minimum	    } elsif ($h_exp > 24 * 3600) {		# Should give a warning if more than 24 hours according to		# <draft-ietf-http-v11-spec-07> section 13.2.4, but I don't		# know how to do it from this function interface, so I just		# make this the maximum value.		return 24 * 3600;	    }	    return $h_exp;	} else {	    return 3600;  # 1 hour is fallback when all else fails	}    }    return $expires - $date;}=item $r->is_freshReturns TRUE if the response is fresh, based on the values offreshness_lifetime() and current_age().  If the response is no longerfresh, then it has to be refetched or revalidated by the originserver.=cutsub is_fresh{    my $self = shift;    $self->freshness_lifetime > $self->current_age;}=item $r->fresh_untilReturns the time when this entiy is no longer fresh.=cutsub fresh_until{    my $self = shift;    return $self->freshness_lifetime - $self->current_age + time;}1;=back =head1 COPYRIGHTCopyright 1995-2001 Gisle Aas.This library is free software; you can redistribute it and/ormodify it under the same terms as Perl itself.=cut