root/trunk/lib/Perlbal/ClientHTTPBase.pm

######################################################################
# Common HTTP functionality for ClientProxy and ClientHTTP
# possible states:
#   reading_headers (initial state, then follows one of two paths)
#     wait_backend, backend_req_sent, wait_res, xfer_res, draining_res
#     wait_stat, wait_open, xfer_disk
# both paths can then go into persist_wait, which means they're waiting
# for another request from the user
#
# Copyright 2004, Danga Interactive, Inc.
# Copyright 2005-2007, Six Apart, Ltd.

package Perlbal::ClientHTTPBase;
use strict;
use warnings;
no  warnings qw(deprecated);

use Sys::Syscall;
use base "Perlbal::Socket";
use HTTP::Date ();
use fields ('service',             # Perlbal::Service object
            'replacement_uri',     # URI to send instead of the one requested; this is used
                                   # to instruct _serve_request to send an index file instead
                                   # of trying to serve a directory and failing
            'scratch',             # extra storage; plugins can use it if they want

            # reproxy support
            'reproxy_file',        # filename the backend told us to start opening
            'reproxy_file_size',   # size of file, once we stat() it
            'reproxy_fh',          # if needed, IO::Handle of fd
            'reproxy_file_offset', # how much we've sent from the file.

            'post_sendfile_cb',    # subref to run after we're done sendfile'ing the current file

            'requests',            # number of requests this object has performed for the user

            # service selector parent
            'selector_svc',        # the original service from which we came
            );

use Fcntl ':mode';
use Errno qw(EPIPE ECONNRESET);
use POSIX ();

# hard-code defaults can be changed with MIME management command
our $MimeType = {qw(
                    css  text/css
                    doc  application/msword
                    gif  image/gif
                    htm  text/html
                    html text/html
                    jpg  image/jpeg
                    js   application/x-javascript
                    mp3  audio/mpeg
                    mpg  video/mpeg
                    pdf  application/pdf
                    png  image/png
                    tif   image/tiff
                    tiff  image/tiff
                    torrent  application/x-bittorrent
                    txt   text/plain
                    zip   application/zip
)};

# ClientHTTPBase
sub new {

    my Perlbal::ClientHTTPBase $self = shift;
    my ($service, $sock, $selector_svc) = @_;
    $self = fields::new($self) unless ref $self;
    $self->SUPER::new($sock);       # init base fields

    $self->{service}         = $service;
    $self->{replacement_uri} = undef;
    $self->{headers_string}  = '';
    $self->{requests}        = 0;
    $self->{scratch}         = {};
    $self->{selector_svc}    = $selector_svc;

    $self->state('reading_headers');

    $self->watch_read(1);
    return $self;
}

sub close {
    my Perlbal::ClientHTTPBase $self = shift;

    # don't close twice
    return if $self->{closed};

    # could contain a closure with circular reference
    $self->{post_sendfile_cb} = undef;

    # close the file we were reproxying, if any
    CORE::close($self->{reproxy_fh}) if $self->{reproxy_fh};

    # now pass up the line
    $self->SUPER::close(@_);
}

# given the response headers we just got, and considering our request
# headers, determine if we should be sending keep-alive header
# information back to the client
sub setup_keepalive {
    my Perlbal::ClientHTTPBase $self = $_[0];
    print "ClientHTTPBase::setup_keepalive($self)\n" if Perlbal::DEBUG >= 2;

    # now get the headers we're using
    my Perlbal::HTTPHeaders $reshd = $_[1];
    my Perlbal::HTTPHeaders $rqhd = $self->{req_headers};

    # for now, we enforce outgoing HTTP 1.0
    $reshd->set_version("1.0");

    # if we came in via a selector service, that's whose settings
    # we respect for persist_client
    my $svc = $self->{selector_svc} || $self->{service};
    my $persist_client = $svc->{persist_client} || 0;
    print "  service's persist_client = $persist_client\n" if Perlbal::DEBUG >= 3;

    # do keep alive if they sent content-length or it's a head request
    my $do_keepalive = $persist_client && $rqhd->req_keep_alive($reshd);
    if ($do_keepalive) {
        print "  doing keep-alive to client\n" if Perlbal::DEBUG >= 3;
        my $timeout = $self->{service}->{persist_client_timeout};
        $reshd->header('Connection', 'keep-alive');
        $reshd->header('Keep-Alive', $timeout ? "timeout=$timeout, max=100" : undef);
    } else {
        print "  doing connection: close\n" if Perlbal::DEBUG >= 3;
        # FIXME: we don't necessarily want to set connection to close,
        # but really set a space-separated list of tokens which are
        # specific to the connection.  "close" and "keep-alive" are
        # just special.
        $reshd->header('Connection', 'close');
        $reshd->header('Keep-Alive', undef);
    }
}

# overridden here from Perlbal::Socket to use the service value
sub max_idle_time {
    return $_[0]->{service}->{persist_client_timeout};
}

# Called when this client is entering a persist_wait state, but before we are returned to base.
sub persist_wait {
    
}

# called when we've finished writing everything to a client and we need
# to reset our state for another request.  returns 1 to mean that we should
# support persistence, 0 means we're discarding this connection.
sub http_response_sent {
    my Perlbal::ClientHTTPBase $self = $_[0];

    # close if we're supposed to
    if (
        ! defined $self->{res_headers} ||
        ! $self->{res_headers}->res_keep_alive($self->{req_headers}) ||
        $self->{do_die}
        )
    {
        # do a final read so we don't have unread_data_waiting and RST
        # the connection.  IE and others send an extra \r\n after POSTs
        my $dummy = $self->read(5);

        # close if we have no response headers or they say to close
        $self->close("no_keep_alive");
        return 0;
    }

    # if they just did a POST, set the flag that says we might expect
    # an unadvertised \r\n coming from some browsers.  Old Netscape
    # 4.x did this on all POSTs, and Firefox/Safari do it on
    # XmlHttpRequest POSTs.
    if ($self->{req_headers}->request_method eq "POST") {
        $self->{ditch_leading_rn} = 1;
    }

    # now since we're doing persistence, uncork so the last packet goes.
    # we will recork when we're processing a new request.
    $self->tcp_cork(0);

    # reset state
    $self->{replacement_uri} = undef;
    $self->{headers_string} = '';
    $self->{req_headers} = undef;
    $self->{res_headers} = undef;
    $self->{reproxy_fh} = undef;
    $self->{reproxy_file} = undef;
    $self->{reproxy_file_size} = 0;
    $self->{reproxy_file_offset} = 0;
    $self->{read_buf} = [];
    $self->{read_ahead} = 0;
    $self->{read_size} = 0;
    $self->{scratch} = {};
    $self->{post_sendfile_cb} = undef;
    $self->state('persist_wait');

    $self->persist_wait;

    if (my $selector_svc = $self->{selector_svc}) {
        if (! $selector_svc->run_hook('return_to_base', $self)){
            $selector_svc->return_to_base($self);
        }
    }

    # NOTE: because we only speak 1.0 to clients they can't have
    # pipeline in a read that we haven't read yet.
    $self->watch_read(1);
    $self->watch_write(0);
    return 1;
}

sub reproxy_fh {
    my Perlbal::ClientHTTPBase $self = shift;

    # setter
    if (@_) {
        my ($fh, $size) = @_;
        $self->state('xfer_disk');
        $self->{reproxy_fh} = $fh;
        $self->{reproxy_file_offset} = 0;
        $self->{reproxy_file_size} = $size;

        my $is_ssl_webserver = ( $self->{service}->{listener}->{sslopts} &&
                               ( $self->{service}->{role} eq 'web_server') );

        unless ($is_ssl_webserver) {
            # call hook that we're reproxying a file
            return $fh if $self->{service}->run_hook("start_send_file", $self);
            # turn on writes (the hook might not have wanted us to)
            $self->watch_write(1);
            return $fh;
        } else { # use aio_read for ssl webserver instead of sendfile

            print "webserver in ssl mode, sendfile disabled!\n"
                if $Perlbal::DEBUG >= 3;

            # turn off writes
            $self->watch_write(0);
            #create filehandle for reading
            my $data = '';
            Perlbal::AIO::aio_read($self->reproxy_fh, 0, 2048, $data, sub {
                # got data? undef is error
                return $self->_simple_response(500) unless $_[0] > 0;

                # seek into the file now so sendfile starts further in
                my $ld = length $data;
                sysseek($self->{reproxy_fh}, $ld, &POSIX::SEEK_SET);
                $self->{reproxy_file_offset} = $ld;
                # reenable writes after we get data
                $self->tcp_cork(1); # by setting reproxy_file_offset above,
                                    # it won't cork, so we cork it
                $self->write($data);
                $self->watch_write(1);
            });
            return 1;
        }
    }

    return $self->{reproxy_fh};
}

sub event_read {
    my Perlbal::ClientHTTPBase $self = shift;

    $self->{alive_time} = $Perlbal::tick_time;

    # see if we have headers?
    die "Shouldn't get here!  This is an abstract base class, pretty much, except in the case of the 'selector' role."
        if $self->{req_headers};

    my $hd = $self->read_request_headers;
    return unless $hd;

    return if $self->{service}->run_hook('start_http_request', $self);

    # we must stop watching for events now, otherwise if there's
    # PUT/POST overflow, it'll be sent to ClientHTTPBase, which can't
    # handle it yet.  must wait for the selector (which has as much
    # time as it wants) to route as to our subclass, which can then
    # re-enable reads.
    $self->watch_read(0);

    my $select = sub {
        # now that we have headers, it's time to tell the selector
        # plugin that it's time for it to select which real service to
        # use
        my $selector = $self->{'service'}->selector();
        return $self->_simple_response(500, "No service selector configured.")
            unless ref $selector eq "CODE";
        $selector->($self);
    };

    my $svc = $self->{'service'};
    if ($svc->{latency}) {
        Danga::Socket->AddTimer($svc->{latency} / 1000, $select);
    } else {
        $select->();
    }
}

sub reproxy_file_done {
    my Perlbal::ClientHTTPBase $self = shift;
    return if $self->{service}->run_hook('reproxy_fh_finished', $self);
    # close the sendfile fd
    CORE::close($self->{reproxy_fh});
    $self->{reproxy_fh} = undef;
    if (my $cb = $self->{post_sendfile_cb}) {
        $cb->();
    } else {
        $self->http_response_sent;
    }
}

# client is ready for more of its file.  so sendfile some more to it.
# (called by event_write when we're actually in this mode)
sub event_write_reproxy_fh {
    my Perlbal::ClientHTTPBase $self = shift;

    my $remain = $self->{reproxy_file_size} - $self->{reproxy_file_offset};
    $self->tcp_cork(1) if $self->{reproxy_file_offset} == 0;
    $self->watch_write(0);

    if ($self->{service}->{listener}->{sslopts}) { # SSL (sendfile does not do SSL)
        return if $self->{closed};
        if ($remain <= 0) { #done
            print "REPROXY SSL done\n" if Perlbal::DEBUG >= 2;
            $self->reproxy_file_done;
            return;
        }
        # queue up next read
        Perlbal::AIO::set_file_for_channel($self->{reproxy_file});
        my $len = $remain > 4096 ? 4096 : $remain; # buffer size
        my $buffer = '';
        Perlbal::AIO::aio_read(
            $self->{reproxy_fh},
            $self->{reproxy_file_offset},
            $len,
            $buffer,
            sub {
                return if $self->{closed};
                # we have buffer to send
                my $rv = $_[0]; # arg is result of sysread
                if (!defined($rv) || $rv <= 0) { # read error
                    # sysseek is called after sysread so $! not valid
                    $self->close('sysread_error');
                    print STDERR "Error w/ reproxy sysread\n";
                    return;
                }
                $self->{reproxy_file_offset} += $rv;
                $self->tcp_cork(1); # by setting reproxy_file_offset above,
                                    # it won't cork, so we cork it
                $self->write($buffer); # start socket send
                $self->watch_write(1);
            } 
        );
        return;
    }

    # cap at 128k sendfiles
    my $to_send = $remain > 128 * 1024 ? 128 * 1024 : $remain;

    my $postread = sub {
        return if $self->{closed};

        my $sent = Perlbal::Socket::sendfile($self->{fd},
                                             fileno($self->{reproxy_fh}),
                                             $to_send);
        #warn "to_send = $to_send, sent = $sent\n";
        print "REPROXY Sent: $sent\n" if Perlbal::DEBUG >= 2;

        if ($sent < 0) {
            return $self->close("epipe")     if $! == EPIPE;
            return $self->close("connreset") if $! == ECONNRESET;
            print STDERR "Error w/ sendfile: $!\n";
            $self->close('sendfile_error');
            return;
        }
        $self->{reproxy_file_offset} += $sent;

        if ($sent >= $remain) {
            $self->reproxy_file_done;
        } else {
            $self->watch_write(1);
        }
    };

    # TODO: way to bypass readahead and go straight to sendfile for common/hot/recent files.
    # something like:
    # if ($hot) { $postread->(); return ; }

    if ($to_send < 0) {
        Perlbal::log('warning', "tried to readahead negative bytes.  filesize=$self->{reproxy_file_size}, offset=$self->{reproxy_file_offset}");
        # this code, doing sendfile, will fail gracefully with return
        # code, not 'die', and we'll close with sendfile_error:
        $postread->();
        return;
    }

    Perlbal::AIO::set_file_for_channel($self->{reproxy_file});
    Perlbal::AIO::aio_readahead($self->{reproxy_fh},
                                $self->{reproxy_file_offset},
                                $to_send, $postread);
}

sub event_write {
    my Perlbal::ClientHTTPBase $self = shift;

    # Any HTTP client is considered alive if it's writable.
    # if it's not writable for 30 seconds, we kill it.
    # subclasses can decide what's appropriate for timeout.
    $self->{alive_time} = $Perlbal::tick_time;

    # if we're sending a filehandle, go do some more sendfile:
    if ($self->{reproxy_fh}) {
        $self->event_write_reproxy_fh;
        return;
    }

    # otherwise just kick-start our write buffer.
    if ($self->write(undef)) {
        # we've written all data in the queue, so stop waiting for
        # write notifications:
        print "All writing done to $self\n" if Perlbal::DEBUG >= 2;
        $self->watch_write(0);
    }
}

# this gets called when a "web" service is serving a file locally.
sub _serve_request {
    my Perlbal::ClientHTTPBase $self = shift;
    my Perlbal::HTTPHeaders $hd = shift;

    my $rm = $hd->request_method;
    unless ($rm eq "HEAD" || $rm eq "GET") {
        return $self->_simple_response(403, "Unimplemented method");
    }

    my $uri = Perlbal::Util::durl($self->{replacement_uri} || $hd->request_uri);
    my Perlbal::Service $svc = $self->{service};

    # start_serve_request hook
    return 1 if $self->{service}->run_hook('start_serve_request', $self, \$uri);

    # don't allow directory traversal
    if ($uri =~ m!/\.\./! || $uri !~ m!^/!) {
        return $self->_simple_response(403, "Bogus URL");
    }

    # double question mark means to serve multiple files, comma separated after the
    # questions.  the uri part before the question mark is the relative base directory
    # TODO: only do this if $uri has ?? and the service also allows it.  otherwise
    # we don't want to mess with anybody's meaning of '??' on the backend service
    return $self->_serve_request_multiple($hd, $uri) if $uri =~ /\?\?/;

    # chop off the query string
    $uri =~ s/\?.*//;

    return $self->_simple_response(500, "Docroot unconfigured")
        unless $svc->{docroot};

    my $file = $svc->{docroot} . $uri;

    # update state, since we're now waiting on stat
    $self->state('wait_stat');

    Perlbal::AIO::aio_stat($file, sub {
        # client's gone anyway
        return if $self->{closed};
        unless (-e _) {
            return if $self->{service}->run_hook('static_get_poststat_file_missing', $self);
            return $self->_simple_response(404);
        }

        my $mtime   = (stat(_))[9];
        my $lastmod = HTTP::Date::time2str($mtime);
        my $ims     = $hd->header("If-Modified-Since") || "";

        # IE sends a request header like "If-Modified-Since: <DATE>; length=<length>"
        # so we have to remove the length bit before comparing it with our date.
        # then we save the length to compare later.
        my $ims_len;
        if ($ims && $ims =~ s/; length=(\d+)//) {
            $ims_len = $1;
        }

        my $not_mod = $ims eq $lastmod && -f _;

        my $res;
        my $not_satisfiable = 0;
        my $size = -s _ if -f _;

        # extra protection for IE, since it's offering the info anyway.  (see above)
        $not_mod = 0 if $ims_len && $ims_len != $size;

        my ($status, $range_start, $range_end) = $hd->range($size);

        if ($not_mod) {
            $res = $self->{res_headers} = Perlbal::HTTPHeaders->new_response(304);
        } elsif ($status == 416) {
            $res = $self->{res_headers} = Perlbal::HTTPHeaders->new_response(416);
            $res->header("Content-Range", $size ? "bytes */$size" : "*");
            $res->header("Content-Length", 0);
            $not_satisfiable = 1;
        } elsif ($status == 206) {
            # partial content
            $res = $self->{res_headers} = Perlbal::HTTPHeaders->new_response(206);
        } else {
            return if $self->{service}->run_hook('static_get_poststat_pre_send', $self, $mtime);
            $res = $self->{res_headers} = Perlbal::HTTPHeaders->new_response(200);
        }

        # now set whether this is keep-alive or not
        $res->header("Date", HTTP::Date::time2str());
        $res->header("Server", "Perlbal");
        $res->header("Last-Modified", $lastmod);

        if (-f _) {
            # advertise that we support byte range requests
            $res->header("Accept-Ranges", "bytes");

            unless ($not_mod || $not_satisfiable) {
                my ($ext) = ($file =~ /\.(\w+)$/);
                $res->header("Content-Type",
                             (defined $ext && exists $MimeType->{$ext}) ? $MimeType->{$ext} : "text/plain");

                unless ($status == 206) {
                    $res->header("Content-Length", $size);
                } else {
                    $res->header("Content-Range", "bytes $range_start-$range_end/$size");
                    $res->header("Content-Length", $range_end - $range_start + 1);
                }
            }

            # has to happen after content-length is set to work:
            $self->setup_keepalive($res);

            return if $self->{service}->run_hook('modify_response_headers', $self);

            if ($rm eq "HEAD" || $not_mod || $not_satisfiable) {
                # we can return already, since we know the size
                $self->tcp_cork(1);
                $self->state('xfer_resp');
                $self->write($res->to_string_ref);
                $self->write(sub { $self->http_response_sent; });
                return;
            }

            # state update
            $self->state('wait_open');

            Perlbal::AIO::aio_open($file, 0, 0, sub {
                my $rp_fh = shift;

                # if client's gone, just close filehandle and abort
                if ($self->{closed}) {
                    CORE::close($rp_fh) if $rp_fh;
                    return;
                }

                # handle errors
                if (! $rp_fh) {
                    # couldn't open the file we had already successfully stat'ed.
                    # FIXME: do 500 vs. 404 vs whatever based on $!
                    return $self->close('aio_open_failure');
                }

                $self->state('xfer_disk');
                $self->tcp_cork(1);  # cork writes to self
                $self->write($res->to_string_ref);

                # seek if partial content
                if ($status == 206) {
                    sysseek($rp_fh, $range_start, &POSIX::SEEK_SET);
                    $size = $range_end - $range_start + 1;
                }

                $self->{reproxy_file} = $file;
                $self->reproxy_fh($rp_fh, $size);
            });

        } elsif (-d _) {
            $self->try_index_files($hd, $res, $uri);
        }
    });
}

sub _serve_request_multiple {
    my Perlbal::ClientHTTPBase $self = shift;
    my ($hd, $uri) = @_;

    my @multiple_files;
    my %statinfo;  # file -> [ stat fields ]

    # double question mark means to serve multiple files, comma
    # separated after the questions.  the uri part before the question
    # mark is the relative base directory
    my ($base, $list) = ($uri =~ /(.+)\?\?(.+)/);

    unless ($base =~ m!/$!) {
        return $self->_simple_response(500, "Base directory (before ??) must end in slash.")
    }

    # and remove any trailing ?.+ on the list, so you can do things like cache busting
    # with a ?v=<modtime> at the end of a list of files.
    $list =~ s/\?.+//;

    my Perlbal::Service $svc = $self->{service};
    return $self->_simple_response(500, "Docroot unconfigured")
        unless $svc->{docroot};

    @multiple_files = split(/,/, $list);

    return $self->_simple_response(403, "Multiple file serving isn't enabled") unless $svc->{enable_concatenate_get};
    return $self->_simple_response(403, "Too many files requested") if @multiple_files > 100;
    return $self->_simple_response(403, "Bogus filenames") if grep { m!(?:\A|/)\.\./! } @multiple_files;

    my $remain = @multiple_files + 1;  # 1 for the base directory
    my $dirbase = $svc->{docroot} . $base;
    foreach my $file ('', @multiple_files) {
        Perlbal::AIO::aio_stat("$dirbase$file", sub {
            $remain--;
            $statinfo{$file} = $! ? [] : [ stat(_) ];
            return if $remain || $self->{closed};
            $self->_serve_request_multiple_poststat($hd, $dirbase, \@multiple_files, \%statinfo);
        });
    }
}

sub _serve_request_multiple_poststat {
    my Perlbal::ClientHTTPBase $self = shift;
    my ($hd, $basedir, $filelist, $stats) = @_;

    # base directory must be a directory
    unless (S_ISDIR($stats->{''}[2] || 0)) {
        return $self->_simple_response(404, "Base directory not a directory");
    }

    # files must all exist
    my $sum_length      = 0;
    my $most_recent_mod = 0;
    my $mime;                  # undef until set, or defaults to text/plain later
    foreach my $f (@$filelist) {
        my $stat = $stats->{$f};
        unless (S_ISREG($stat->[2] || 0)) {
            return if $self->{service}->run_hook('concat_get_poststat_file_missing', $self);
            return $self->_simple_response(404, "One or more file does not exist");
        }
        if (!$mime && $f =~ /\.(\w+)$/ && $MimeType->{$1}) {
            $mime = $MimeType->{$1};
        }
        $sum_length     += $stat->[7];
        $most_recent_mod = $stat->[9] if
            $stat->[9] >$most_recent_mod;
    }
    $mime ||= 'text/plain';

    my $lastmod = HTTP::Date::time2str($most_recent_mod);
    my $ims     = $hd->header("If-Modified-Since") || "";

    # IE sends a request header like "If-Modified-Since: <DATE>; length=<length>"
    # so we have to remove the length bit before comparing it with our date.
    # then we save the length to compare later.
    my $ims_len;
    if ($ims && $ims =~ s/; length=(\d+)//) {
        $ims_len = $1;
    }

    # What is -f _ doing here? don't we detect the existence of all files above in the loop?
    my $not_mod = $ims eq $lastmod && -f _;

    my $res;
    if ($not_mod) {
        $res = $self->{res_headers} = Perlbal::HTTPHeaders->new_response(304);
    } else {
        return if $self->{service}->run_hook('concat_get_poststat_pre_send', $self, $most_recent_mod);
        $res = $self->{res_headers} = Perlbal::HTTPHeaders->new_response(200);
        $res->header("Content-Length", $sum_length);
    }

    $res->header("Date", HTTP::Date::time2str());
    $res->header("Server", "Perlbal");
    $res->header("Last-Modified", $lastmod);
    $res->header("Content-Type",   $mime);
    # has to happen after content-length is set to work:
    $self->setup_keepalive($res);
    return if $self->{service}->run_hook('modify_response_headers', $self);

    if ($hd->request_method eq "HEAD" || $not_mod) {
        # we can return already, since we know the size
        $self->tcp_cork(1);
        $self->state('xfer_resp');
        $self->write($res->to_string_ref);
        $self->write(sub { $self->http_response_sent; });
        return;
    }

    $self->tcp_cork(1);  # cork writes to self
    $self->write($res->to_string_ref);
    $self->state('wait_open');

    # gotta send all files, one by one...
    my @remain = @$filelist;
    $self->{post_sendfile_cb} = sub {
        unless (@remain) {
            $self->write(sub { $self->http_response_sent; });
            return;
        }

        my $file     = shift @remain;
        my $fullfile = "$basedir$file";
        my $size     = $stats->{$file}[7];

        Perlbal::AIO::aio_open($fullfile, 0, 0, sub {
            my $rp_fh = shift;

            # if client's gone, just close filehandle and abort
            if ($self->{closed}) {
                CORE::close($rp_fh) if $rp_fh;
                  return;
              }

            # handle errors
            if (! $rp_fh) {
                # couldn't open the file we had already successfully stat'ed.
                # FIXME: do 500 vs. 404 vs whatever based on $!
                return $self->close('aio_open_failure');
            }

            $self->{reproxy_file}     = $file;
            $self->reproxy_fh($rp_fh, $size);
        });
    };
    $self->{post_sendfile_cb}->();
}

sub check_req_headers {
    my Perlbal::ClientHTTPBase $self = shift;
    my Perlbal::HTTPHeaders $hds = $self->{req_headers};

    if ($self->{service}->trusted_ip($self->peer_ip_string)) {
        my @ips = split /,\s*/, ($hds->header("X-Forwarded-For") || '');

        # This list may be empty, and that's OK, in that case we should unset the
        # observed_ip_string, so no matter what we'll use the 0th element, whether
        # it happens to be an ip string, or undef.
        $self->observed_ip_string($ips[0]);
    }

    return;
}

sub try_index_files {
    my Perlbal::ClientHTTPBase $self = shift;
    my ($hd, $res, $uri, $filepos) = @_;

    # make sure this starts at 0 initially, and fail if it's past the end
    $filepos ||= 0;
    if ($filepos >= scalar(@{$self->{service}->{index_files} || []})) {
        unless ($self->{service}->{dirindexing}) {
            # just inform them that listing is disabled
            $self->_simple_response(200, "Directory listing disabled");
            return;
        }

        # ensure uri has one and only one trailing slash for better URLs
        $uri =~ s!/*$!/!;

        # open the directory and create an index
        my $body = "<html><body>";
        my $file = $self->{service}->{docroot} . $uri;

        $res->header("Content-Type", "text/html");
        opendir(D, $file);
        foreach my $de (sort readdir(D)) {
            if (-d "$file/$de") {
                $body .= "<b><a href='$uri$de/'>$de</a></b><br />\n";
            } else {
                $body .= "<a href='$uri$de'>$de</a><br />\n";
            }
        }
        closedir(D);

        $body .= "</body></html>";
        $res->header("Content-Length", length($body));
        $self->setup_keepalive($res);

        $self->state('xfer_resp');
        $self->tcp_cork(1);  # cork writes to self
        $self->write($res->to_string_ref);
        $self->write(\$body);
        $self->write(sub { $self->http_response_sent; });
        return;
    }

    # construct the file path we need to check
    my $file = $self->{service}->{index_files}->[$filepos];
    my $fullpath = $self->{service}->{docroot} . $uri . '/' . $file;

    # now see if it exists
    Perlbal::AIO::aio_stat($fullpath, sub {
        return if $self->{closed};
        return $self->try_index_files($hd, $res, $uri, $filepos + 1) unless -f _;

        # at this point the file exists, so we just want to serve it
        $self->{replacement_uri} = $uri . '/' . $file;
        return $self->_serve_request($hd);
    });
}

sub _simple_response {
    my Perlbal::ClientHTTPBase $self = shift;
    my ($code, $msg) = @_;  # or bodyref

    my $res = $self->{res_headers} = Perlbal::HTTPHeaders->new_response($code);

    my $body;
    if ($code != 204 && $code != 304) {
        $res->header("Content-Type", "text/html");
        my $en = $res->http_code_english;
        $body = "<h1>$code" . ($en ? " - $en" : "") . "</h1>\n";
        $body .= $msg if $msg;
        $res->header('Content-Length', length($body));
    }

    $res->header('Server', 'Perlbal');

    $self->setup_keepalive($res);

    $self->state('xfer_resp');
    $self->tcp_cork(1);  # cork writes to self
    $self->write($res->to_string_ref);
    if (defined $body) {
        unless ($self->{req_headers} && $self->{req_headers}->request_method eq 'HEAD') {
            # don't write body for head requests
            $self->write(\$body);
        }
    }
    $self->write(sub { $self->http_response_sent; });
    return 1;
}


sub send_response {
    my Perlbal::ClientHTTPBase $self = shift;

    $self->watch_read(0);
    $self->watch_write(1);
    return $self->_simple_response(@_);
}

# method that sends a 500 to the user but logs it and any extra information
# we have about the error in question
sub system_error {
    my Perlbal::ClientHTTPBase $self = shift;
    my ($msg, $info) = @_;

    # log to syslog
    Perlbal::log('warning', "system error: $msg ($info)");

    # and return a 500
    return $self->send_response(500, $msg);
}

sub event_err {  my $self = shift; $self->close('error'); }
sub event_hup {  my $self = shift; $self->close('hup'); }

sub _sock_port {
    my $name = $_[0];
    my $port = eval { (Socket::sockaddr_in($name))[0] };
    return $port unless $@;
    # fallback to IPv6:
    return (Socket6::unpack_sockaddr_in($name))[0];
}

sub as_string {
    my Perlbal::ClientHTTPBase $self = shift;

    my $ret = $self->SUPER::as_string;
    my $name = $self->{sock} ? getsockname($self->{sock}) : undef;
    my $lport = $name ? _sock_port($name) : undef;
    my $observed = $self->observed_ip_string;
    $ret .= ": localport=$lport" if $lport;
    $ret .= "; observed_ip=$observed" if defined $observed;
    $ret .= "; reqs=$self->{requests}";
    $ret .= "; $self->{state}";

    my $hd = $self->{req_headers};
    if (defined $hd) {
        my $host = $hd->header('Host') || 'unknown';
        $ret .= "; http://$host" . $hd->request_uri;
    }

    return $ret;
}

1;

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