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package LWP::RobotUA; use base qw(LWP::UserAgent); our $VERSION = '6.34'; require WWW::RobotRules; require HTTP::Request; require HTTP::Response; use Carp (); use HTTP::Status (); use HTTP::Date qw(time2str); use strict; # # Additional attributes in addition to those found in LWP::UserAgent: # # $self->{'delay'} Required delay between request to the same # server in minutes. # # $self->{'rules'} A WWW::RobotRules object # sub new { my $class = shift; my %cnf; if (@_ < 4) { # legacy args @cnf{qw(agent from rules)} = @_; } else { %cnf = @_; } Carp::croak('LWP::RobotUA agent required') unless $cnf{agent}; Carp::croak('LWP::RobotUA from address required') unless $cnf{from} && $cnf{from} =~ m/\@/; my $delay = delete $cnf{delay} || 1; my $use_sleep = delete $cnf{use_sleep}; $use_sleep = 1 unless defined($use_sleep); my $rules = delete $cnf{rules}; my $self = LWP::UserAgent->new(%cnf); $self = bless $self, $class; $self->{'delay'} = $delay; # minutes $self->{'use_sleep'} = $use_sleep; if ($rules) { $rules->agent($cnf{agent}); $self->{'rules'} = $rules; } else { $self->{'rules'} = WWW::RobotRules->new($cnf{agent}); } $self; } sub delay { shift->_elem('delay', @_); } sub use_sleep { shift->_elem('use_sleep', @_); } sub agent { my $self = shift; my $old = $self->SUPER::agent(@_); if (@_) { # Changing our name means to start fresh $self->{'rules'}->agent($self->{'agent'}); } $old; } sub rules { my $self = shift; my $old = $self->_elem('rules', @_); $self->{'rules'}->agent($self->{'agent'}) if @_; $old; } sub no_visits { my($self, $netloc) = @_; $self->{'rules'}->no_visits($netloc) || 0; } *host_count = \&no_visits; # backwards compatibility with LWP-5.02 sub host_wait { my($self, $netloc) = @_; return undef unless defined $netloc; my $last = $self->{'rules'}->last_visit($netloc); if ($last) { my $wait = int($self->{'delay'} * 60 - (time - $last)); $wait = 0 if $wait < 0; return $wait; } return 0; } sub simple_request { my($self, $request, $arg, $size) = @_; # Do we try to access a new server? my $allowed = $self->{'rules'}->allowed($request->uri); if ($allowed < 0) { # Host is not visited before, or robots.txt expired; fetch "robots.txt" my $robot_url = $request->uri->clone; $robot_url->path("robots.txt"); $robot_url->query(undef); # make access to robot.txt legal since this will be a recursive call $self->{'rules'}->parse($robot_url, ""); my $robot_req = HTTP::Request->new('GET', $robot_url); my $parse_head = $self->parse_head(0); my $robot_res = $self->request($robot_req); $self->parse_head($parse_head); my $fresh_until = $robot_res->fresh_until; my $content = ""; if ($robot_res->is_success && $robot_res->content_is_text) { $content = $robot_res->decoded_content; $content = "" unless $content && $content =~ /^\s*Disallow\s*:/mi; } $self->{'rules'}->parse($robot_url, $content, $fresh_until); # recalculate allowed... $allowed = $self->{'rules'}->allowed($request->uri); } # Check rules unless ($allowed) { my $res = HTTP::Response->new( HTTP::Status::RC_FORBIDDEN, 'Forbidden by robots.txt'); $res->request( $request ); # bind it to that request return $res; } my $netloc = eval { local $SIG{__DIE__}; $request->uri->host_port; }; my $wait = $self->host_wait($netloc); if ($wait) { if ($self->{'use_sleep'}) { sleep($wait) } else { my $res = HTTP::Response->new( HTTP::Status::RC_SERVICE_UNAVAILABLE, 'Please, slow down'); $res->header('Retry-After', time2str(time + $wait)); $res->request( $request ); # bind it to that request return $res; } } # Perform the request my $res = $self->SUPER::simple_request($request, $arg, $size); $self->{'rules'}->visit($netloc); $res; } sub as_string { my $self = shift; my @s; push(@s, "Robot: $self->{'agent'} operated by $self->{'from'} [$self]"); push(@s, " Minimum delay: " . int($self->{'delay'}*60) . "s"); push(@s, " Will sleep if too early") if $self->{'use_sleep'}; push(@s, " Rules = $self->{'rules'}"); join("\n", @s, ''); } 1; __END__ =pod =head1 NAME LWP::RobotUA - a class for well-behaved Web robots =head1 SYNOPSIS use LWP::RobotUA; my $ua = LWP::RobotUA->new('my-robot/0.1', 'me@foo.com'); $ua->delay(10); # be very nice -- max one hit every ten minutes! ... # Then just use it just like a normal LWP::UserAgent: my $response = $ua->get('http://whatever.int/...'); ... =head1 DESCRIPTION This class implements a user agent that is suitable for robot applications. Robots should be nice to the servers they visit. They should consult the F</robots.txt> file to ensure that they are welcomed and they should not make requests too frequently. But before you consider writing a robot, take a look at L<URL:http://www.robotstxt.org/>. When you use an I<LWP::RobotUA> object as your user agent, then you do not really have to think about these things yourself; C<robots.txt> files are automatically consulted and obeyed, the server isn't queried too rapidly, and so on. Just send requests as you do when you are using a normal I<LWP::UserAgent> object (using C<< $ua->get(...) >>, C<< $ua->head(...) >>, C<< $ua->request(...) >>, etc.), and this special agent will make sure you are nice. =head1 METHODS The LWP::RobotUA is a sub-class of L<LWP::UserAgent> and implements the same methods. In addition the following methods are provided: =head2 new my $ua = LWP::RobotUA->new( %options ) my $ua = LWP::RobotUA->new( $agent, $from ) my $ua = LWP::RobotUA->new( $agent, $from, $rules ) The LWP::UserAgent options C<agent> and C<from> are mandatory. The options C<delay>, C<use_sleep> and C<rules> initialize attributes private to the RobotUA. If C<rules> are not provided, then C<WWW::RobotRules> is instantiated providing an internal database of F<robots.txt>. It is also possible to just pass the value of C<agent>, C<from> and optionally C<rules> as plain positional arguments. =head2 delay my $delay = $ua->delay; $ua->delay( $minutes ); Get/set the minimum delay between requests to the same server, in I<minutes>. The default is C<1> minute. Note that this number doesn't have to be an integer; for example, this sets the delay to C<10> seconds: $ua->delay(10/60); =head2 use_sleep my $bool = $ua->use_sleep; $ua->use_sleep( $boolean ); Get/set a value indicating whether the UA should L<LWP::RobotUA/sleep> if requests arrive too fast, defined as C<< $ua->delay >> minutes not passed since last request to the given server. The default is true. If this value is false then an internal C<SERVICE_UNAVAILABLE> response will be generated. It will have a C<Retry-After> header that indicates when it is OK to send another request to this server. =head2 rules my $rules = $ua->rules; $ua->rules( $rules ); Set/get which I<WWW::RobotRules> object to use. =head2 no_visits my $num = $ua->no_visits( $netloc ) Returns the number of documents fetched from this server host. Yeah I know, this method should probably have been named C<num_visits> or something like that. :-( =head2 host_wait my $num = $ua->host_wait( $netloc ) Returns the number of I<seconds> (from now) you must wait before you can make a new request to this host. =head2 as_string my $string = $ua->as_string; Returns a string that describes the state of the UA. Mainly useful for debugging. =head1 SEE ALSO L<LWP::UserAgent>, L<WWW::RobotRules> =head1 COPYRIGHT Copyright 1996-2004 Gisle Aas. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. =cut