httpd/support/logresolve.pl.in

	logresolve.pl.in revision ce9621257ef9e54c1bbe5ad8a5f445a1f211c2dc
#!@perlbin@
#
# Copyright 2000-2004 Apache Software Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
# logresolve.pl
#
# v 1.2 by robh imdb.com
#
# usage: logresolve.pl <infile >outfile
#
# input = Apache/NCSA/.. logfile with IP numbers at start of lines
# output = same logfile with IP addresses resolved to hostnames where
#  name lookups succeeded.
#
# this differs from the C based 'logresolve' in that this script
# spawns a number ($CHILDREN) of subprocesses to resolve addresses
# concurrently and sets a short timeout ($TIMEOUT) for each lookup in
# order to keep things moving quickly.
#
# the parent process handles caching of IP->hostnames using a Perl hash
# it also avoids sending the same IP to multiple child processes to be
# resolved multiple times concurrently.
#
# Depending on the settings of $CHILDREN and $TIMEOUT you should see
# significant reductions in the overall time taken to resolve your
# logfiles. With $CHILDREN=40 and $TIMEOUT=5 I've seen 200,000 - 300,000
# logfile lines processed per hour compared to ~45,000 per hour
# with 'logresolve'.
#
# I haven't yet seen any noticable reduction in the percentage of IPs
# that fail to get resolved. Your mileage will no doubt vary. 5s is long
# enough to wait IMO.
#
# Known to work with FreeBSD 2.2
# Known to have problems with Solaris
#
# 980417 - use 'sockaddr_un' for bind/connect to make the script work
#  with linux. Fix from Luuk de Boer <luuk_de_boer pi.net>

require 5.004;

$|=1;

use FileHandle;
use Socket;

use strict;
no strict 'refs';

use vars qw($PROTOCOL);
$PROTOCOL = 0;

my $CHILDREN = 40;
my $TIMEOUT  = 5;

my $filename;
my %hash = ();
my $parent = $$;

my @children = ();
for (my $child = 1; $child <=$CHILDREN; $child++) {
    my $f = fork();
    if (!$f) {
        $filename = "./.socket.$parent.$child";
        if (-e $filename) { unlink($filename) || warn "$filename .. $!\n";}
        &child($child);
        exit(0);
    }
    push(@children, $f);
}

&parent;
&cleanup;

## remove all temporary files before shutting down
sub cleanup {
     # die kiddies, die
    kill(15, @children);
    for (my $child = 1; $child <=$CHILDREN; $child++) {
        if (-e "./.socket.$parent.$child") {
            unlink("./.socket.$parent.$child")
                || warn ".socket.$parent.$child $!";
        }
    }
}

sub parent {
    # Trap some possible signals to trigger temp file cleanup
    $SIG{'KILL'} = $SIG{'INT'} = $SIG{'PIPE'} = \&cleanup;

    my %CHILDSOCK;
    my $filename;

     ## fork child processes. Each child will create a socket connection
     ## to this parent and use an unique temp filename to do so.
    for (my $child = 1; $child <=$CHILDREN; $child++) {
        $CHILDSOCK{$child}= FileHandle->new;

        if (!socket($CHILDSOCK{$child}, AF_UNIX, SOCK_STREAM, $PROTOCOL)) {
            warn "parent socket to child failed $!";
        }
        $filename = "./.socket.$parent.$child";
        my $response;
        do {
            $response = connect($CHILDSOCK{$child}, sockaddr_un($filename));
            if ($response != 1) {
                sleep(1);
            }
        } while ($response != 1);
        $CHILDSOCK{$child}->autoflush;
    }
    ## All child processes should now be ready or at worst warming up

    my (@buffer, $child, $ip, $rest, $hostname, $response);
     ## read the logfile lines from STDIN
    while(<STDIN>) {
        @buffer = ();   # empty the logfile line buffer array.
        $child = 1;     # children are numbered 1..N, start with #1

        # while we have a child to talk to and data to give it..
        do {
            push(@buffer, $_);                  # buffer the line
            ($ip, $rest) = split(/ /, $_, 2);   # separate IP form rest

            unless ($hash{$ip}) {               # resolve if unseen IP
                $CHILDSOCK{$child}->print("$ip\n"); # pass IP to next child
                $hash{$ip} = $ip;               # don't look it up again.
                $child++;
            }
        } while (($child < ($CHILDREN-1)) and ($_ = <STDIN>));

         ## now poll each child for a response
        while (--$child > 0) {
            $response = $CHILDSOCK{$child}->getline;
            chomp($response);
             # child sends us back both the IP and HOSTNAME, no need for us
             # to remember what child received any given IP, and no worries
             # what order we talk to the children
            ($ip, $hostname) = split(/\|/, $response, 2);
            $hash{$ip} = $hostname;
        }

         # resolve all the logfiles lines held in the log buffer array..
        for (my $line = 0; $line <=$#buffer; $line++) {
             # get next buffered line
            ($ip, $rest) = split(/ /, $buffer[$line], 2);
             # separate IP from rest and replace with cached hostname
            printf STDOUT ("%s %s", $hash{$ip}, $rest);
        }
    }
}

########################################

sub child {
     # arg = numeric ID - how the parent refers to me
    my $me = shift;

     # add trap for alarm signals.
    $SIG{'ALRM'} = sub { die "alarmed"; };

     # create a socket to communicate with parent
    socket(INBOUND, AF_UNIX, SOCK_STREAM, $PROTOCOL)
        || die "Error with Socket: !$\n";
    $filename = "./.socket.$parent.$me";
    bind(INBOUND, sockaddr_un($filename))
        || die "Error Binding $filename: $!\n";
    listen(INBOUND, 5) || die "Error Listening: $!\n";

    my ($ip, $send_back);
    my $talk = FileHandle->new;

     # accept a connection from the parent process. We only ever have
     # have one connection where we exchange 1 line of info with the
     # parent.. 1 line in (IP address), 1 line out (IP + hostname).
    accept($talk, INBOUND) || die "Error Accepting: $!\n";
     # disable I/O buffering just in case
    $talk->autoflush;
     # while the parent keeps sending data, we keep responding..
    while(($ip = $talk->getline)) {
        chomp($ip);
         # resolve the IP if time permits and send back what we found..
        $send_back = sprintf("%s|%s", $ip, &nslookup($ip));
        $talk->print($send_back."\n");
    }
}

# perform a time restricted hostname lookup.
sub nslookup {
     # get the IP as an arg
    my $ip = shift;
    my $hostname = undef;

     # do the hostname lookup inside an eval. The eval will use the
     # already configured SIGnal handler and drop out of the {} block
     # regardless of whether the alarm occured or not.
    eval {
        alarm($TIMEOUT);
        $hostname = gethostbyaddr(gethostbyname($ip), AF_INET);
        alarm(0);
    };
    if ($@ =~ /alarm/) {
         # useful for debugging perhaps..
        # print "alarming, isn't it? ($ip)";
    }

     # return the hostname or the IP address itself if there is no hostname
    $hostname ne "" ? $hostname : $ip;
}