Initial class construction
This commit is contained in:
João Narciso
453
Git/usr/share/perl5/vendor_perl/WWW/RobotRules.pm
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453
Git/usr/share/perl5/vendor_perl/WWW/RobotRules.pm
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package WWW::RobotRules;
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$VERSION = "6.02";
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sub Version { $VERSION; }
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use strict;
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use URI ();
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sub new {
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my($class, $ua) = @_;
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# This ugly hack is needed to ensure backwards compatibility.
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# The "WWW::RobotRules" class is now really abstract.
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$class = "WWW::RobotRules::InCore" if $class eq "WWW::RobotRules";
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my $self = bless { }, $class;
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$self->agent($ua);
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$self;
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}
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sub parse {
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my($self, $robot_txt_uri, $txt, $fresh_until) = @_;
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$robot_txt_uri = URI->new("$robot_txt_uri");
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my $netloc = $robot_txt_uri->host . ":" . $robot_txt_uri->port;
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$self->clear_rules($netloc);
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$self->fresh_until($netloc, $fresh_until || (time + 365*24*3600));
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my $ua;
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my $is_me = 0; # 1 iff this record is for me
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my $is_anon = 0; # 1 iff this record is for *
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my $seen_disallow = 0; # watch for missing record separators
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my @me_disallowed = (); # rules disallowed for me
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my @anon_disallowed = (); # rules disallowed for *
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# blank lines are significant, so turn CRLF into LF to avoid generating
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# false ones
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$txt =~ s/\015\012/\012/g;
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# split at \012 (LF) or \015 (CR) (Mac text files have just CR for EOL)
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for(split(/[\012\015]/, $txt)) {
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# Lines containing only a comment are discarded completely, and
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# therefore do not indicate a record boundary.
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next if /^\s*\#/;
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s/\s*\#.*//; # remove comments at end-of-line
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if (/^\s*$/) { # blank line
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last if $is_me; # That was our record. No need to read the rest.
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$is_anon = 0;
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$seen_disallow = 0;
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}
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elsif (/^\s*User-Agent\s*:\s*(.*)/i) {
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$ua = $1;
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$ua =~ s/\s+$//;
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if ($seen_disallow) {
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# treat as start of a new record
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$seen_disallow = 0;
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last if $is_me; # That was our record. No need to read the rest.
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$is_anon = 0;
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}
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if ($is_me) {
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# This record already had a User-agent that
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# we matched, so just continue.
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}
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elsif ($ua eq '*') {
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$is_anon = 1;
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}
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elsif($self->is_me($ua)) {
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$is_me = 1;
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}
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}
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elsif (/^\s*Disallow\s*:\s*(.*)/i) {
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unless (defined $ua) {
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warn "RobotRules <$robot_txt_uri>: Disallow without preceding User-agent\n" if $^W;
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$is_anon = 1; # assume that User-agent: * was intended
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}
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my $disallow = $1;
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$disallow =~ s/\s+$//;
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$seen_disallow = 1;
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if (length $disallow) {
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my $ignore;
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eval {
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my $u = URI->new_abs($disallow, $robot_txt_uri);
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$ignore++ if $u->scheme ne $robot_txt_uri->scheme;
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$ignore++ if lc($u->host) ne lc($robot_txt_uri->host);
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$ignore++ if $u->port ne $robot_txt_uri->port;
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$disallow = $u->path_query;
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$disallow = "/" unless length $disallow;
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};
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next if $@;
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next if $ignore;
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}
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if ($is_me) {
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push(@me_disallowed, $disallow);
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}
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elsif ($is_anon) {
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push(@anon_disallowed, $disallow);
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}
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}
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elsif (/\S\s*:/) {
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# ignore
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}
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else {
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warn "RobotRules <$robot_txt_uri>: Malformed record: <$_>\n" if $^W;
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}
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}
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if ($is_me) {
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$self->push_rules($netloc, @me_disallowed);
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}
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else {
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$self->push_rules($netloc, @anon_disallowed);
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}
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}
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#
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# Returns TRUE if the given name matches the
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# name of this robot
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#
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sub is_me {
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my($self, $ua_line) = @_;
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my $me = $self->agent;
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# See whether my short-name is a substring of the
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# "User-Agent: ..." line that we were passed:
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if(index(lc($me), lc($ua_line)) >= 0) {
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return 1;
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}
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else {
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return '';
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}
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}
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sub allowed {
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my($self, $uri) = @_;
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$uri = URI->new("$uri");
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return 1 unless $uri->scheme eq 'http' or $uri->scheme eq 'https';
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# Robots.txt applies to only those schemes.
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my $netloc = $uri->host . ":" . $uri->port;
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my $fresh_until = $self->fresh_until($netloc);
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return -1 if !defined($fresh_until) || $fresh_until < time;
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my $str = $uri->path_query;
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my $rule;
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for $rule ($self->rules($netloc)) {
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return 1 unless length $rule;
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return 0 if index($str, $rule) == 0;
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}
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return 1;
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}
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# The following methods must be provided by the subclass.
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sub agent;
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sub visit;
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sub no_visits;
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sub last_visits;
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sub fresh_until;
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sub push_rules;
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sub clear_rules;
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sub rules;
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sub dump;
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package WWW::RobotRules::InCore;
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use vars qw(@ISA);
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@ISA = qw(WWW::RobotRules);
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sub agent {
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my ($self, $name) = @_;
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my $old = $self->{'ua'};
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if ($name) {
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# Strip it so that it's just the short name.
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# I.e., "FooBot" => "FooBot"
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# "FooBot/1.2" => "FooBot"
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# "FooBot/1.2 [http://foobot.int; foo@bot.int]" => "FooBot"
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$name = $1 if $name =~ m/(\S+)/; # get first word
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$name =~ s!/.*!!; # get rid of version
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unless ($old && $old eq $name) {
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delete $self->{'loc'}; # all old info is now stale
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$self->{'ua'} = $name;
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}
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}
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$old;
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}
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sub visit {
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my($self, $netloc, $time) = @_;
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return unless $netloc;
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$time ||= time;
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$self->{'loc'}{$netloc}{'last'} = $time;
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my $count = \$self->{'loc'}{$netloc}{'count'};
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if (!defined $$count) {
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$$count = 1;
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}
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else {
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$$count++;
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}
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}
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sub no_visits {
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my ($self, $netloc) = @_;
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$self->{'loc'}{$netloc}{'count'};
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}
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sub last_visit {
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my ($self, $netloc) = @_;
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$self->{'loc'}{$netloc}{'last'};
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}
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sub fresh_until {
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my ($self, $netloc, $fresh_until) = @_;
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my $old = $self->{'loc'}{$netloc}{'fresh'};
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if (defined $fresh_until) {
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$self->{'loc'}{$netloc}{'fresh'} = $fresh_until;
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}
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$old;
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}
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sub push_rules {
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my($self, $netloc, @rules) = @_;
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push (@{$self->{'loc'}{$netloc}{'rules'}}, @rules);
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}
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sub clear_rules {
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my($self, $netloc) = @_;
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delete $self->{'loc'}{$netloc}{'rules'};
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}
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sub rules {
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my($self, $netloc) = @_;
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if (defined $self->{'loc'}{$netloc}{'rules'}) {
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return @{$self->{'loc'}{$netloc}{'rules'}};
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}
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else {
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return ();
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}
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}
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sub dump
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{
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my $self = shift;
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for (keys %$self) {
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next if $_ eq 'loc';
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print "$_ = $self->{$_}\n";
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}
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for (keys %{$self->{'loc'}}) {
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my @rules = $self->rules($_);
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print "$_: ", join("; ", @rules), "\n";
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}
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}
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1;
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__END__
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# Bender: "Well, I don't have anything else
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# planned for today. Let's get drunk!"
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=head1 NAME
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WWW::RobotRules - database of robots.txt-derived permissions
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=head1 SYNOPSIS
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use WWW::RobotRules;
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my $rules = WWW::RobotRules->new('MOMspider/1.0');
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use LWP::Simple qw(get);
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{
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my $url = "http://some.place/robots.txt";
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my $robots_txt = get $url;
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$rules->parse($url, $robots_txt) if defined $robots_txt;
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}
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{
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my $url = "http://some.other.place/robots.txt";
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my $robots_txt = get $url;
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$rules->parse($url, $robots_txt) if defined $robots_txt;
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}
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# Now we can check if a URL is valid for those servers
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# whose "robots.txt" files we've gotten and parsed:
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if($rules->allowed($url)) {
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$c = get $url;
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...
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}
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=head1 DESCRIPTION
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This module parses F</robots.txt> files as specified in
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"A Standard for Robot Exclusion", at
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<http://www.robotstxt.org/wc/norobots.html>
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Webmasters can use the F</robots.txt> file to forbid conforming
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robots from accessing parts of their web site.
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The parsed files are kept in a WWW::RobotRules object, and this object
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provides methods to check if access to a given URL is prohibited. The
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same WWW::RobotRules object can be used for one or more parsed
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F</robots.txt> files on any number of hosts.
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The following methods are provided:
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=over 4
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=item $rules = WWW::RobotRules->new($robot_name)
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This is the constructor for WWW::RobotRules objects. The first
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argument given to new() is the name of the robot.
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=item $rules->parse($robot_txt_url, $content, $fresh_until)
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The parse() method takes as arguments the URL that was used to
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retrieve the F</robots.txt> file, and the contents of the file.
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=item $rules->allowed($uri)
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Returns TRUE if this robot is allowed to retrieve this URL.
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=item $rules->agent([$name])
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Get/set the agent name. NOTE: Changing the agent name will clear the robots.txt
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rules and expire times out of the cache.
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=back
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=head1 ROBOTS.TXT
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The format and semantics of the "/robots.txt" file are as follows
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(this is an edited abstract of
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<http://www.robotstxt.org/wc/norobots.html>):
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The file consists of one or more records separated by one or more
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blank lines. Each record contains lines of the form
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<field-name>: <value>
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The field name is case insensitive. Text after the '#' character on a
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line is ignored during parsing. This is used for comments. The
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following <field-names> can be used:
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=over 3
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=item User-Agent
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The value of this field is the name of the robot the record is
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describing access policy for. If more than one I<User-Agent> field is
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present the record describes an identical access policy for more than
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one robot. At least one field needs to be present per record. If the
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value is '*', the record describes the default access policy for any
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robot that has not not matched any of the other records.
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The I<User-Agent> fields must occur before the I<Disallow> fields. If a
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record contains a I<User-Agent> field after a I<Disallow> field, that
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constitutes a malformed record. This parser will assume that a blank
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line should have been placed before that I<User-Agent> field, and will
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break the record into two. All the fields before the I<User-Agent> field
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will constitute a record, and the I<User-Agent> field will be the first
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field in a new record.
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=item Disallow
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The value of this field specifies a partial URL that is not to be
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visited. This can be a full path, or a partial path; any URL that
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starts with this value will not be retrieved
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=back
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Unrecognized records are ignored.
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=head1 ROBOTS.TXT EXAMPLES
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The following example "/robots.txt" file specifies that no robots
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should visit any URL starting with "/cyberworld/map/" or "/tmp/":
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User-agent: *
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Disallow: /cyberworld/map/ # This is an infinite virtual URL space
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Disallow: /tmp/ # these will soon disappear
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This example "/robots.txt" file specifies that no robots should visit
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any URL starting with "/cyberworld/map/", except the robot called
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"cybermapper":
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User-agent: *
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Disallow: /cyberworld/map/ # This is an infinite virtual URL space
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# Cybermapper knows where to go.
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User-agent: cybermapper
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Disallow:
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This example indicates that no robots should visit this site further:
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# go away
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User-agent: *
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Disallow: /
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This is an example of a malformed robots.txt file.
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# robots.txt for ancientcastle.example.com
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# I've locked myself away.
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User-agent: *
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Disallow: /
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# The castle is your home now, so you can go anywhere you like.
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User-agent: Belle
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Disallow: /west-wing/ # except the west wing!
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# It's good to be the Prince...
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User-agent: Beast
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Disallow:
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This file is missing the required blank lines between records.
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However, the intention is clear.
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=head1 SEE ALSO
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L<LWP::RobotUA>, L<WWW::RobotRules::AnyDBM_File>
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=head1 COPYRIGHT
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Copyright 1995-2009, Gisle Aas
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Copyright 1995, Martijn Koster
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This library is free software; you can redistribute it and/or
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modify it under the same terms as Perl itself.
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Reference in New Issue
Block a user