Google Redirect Rewrite memory usage

Image courtesy of Open Clip Art Library

I previously found out that you can pretty easily rewrite url's for Squid. Today I noticed Squid launches a bunch of child processes to do the url rewriting. I got curious about the memory usage. I had a feeling that the Perl version would not consume as much memory as PHP and it appears it is indeed so.

I tested both PHP and Perl versions to see how much memory they would consume. First I checked the memory usage of the PHP version after browsing a bit. Then I changed squid.conf to use the Perl version and again checked the memory usage. Squid had just launched one googlerewriter child process, so I browsed some more and then checked again. I'm guessing Squid starts the processes when it actually needs them.(ps. Documentation confirmes this) Anyway some processes then appeared to have been launched.

Fields

MAJFL

Major page fault: The number of major page faults that have occurred with this process

TRS (kB)

Text resident set: The amount of physical memory devoted to executable code

DRS (kB)

Data resident set: The amount of physical memory devoted to other than executable code

RSS (kB)

Resident set size: The portion of a process's memory that is held in RAM. The rest of the memory exists in swap or the filesystem (never loaded or previously unloaded parts of the executable).

Even for a tiny script php version caused some page faults and it's using way too much memory for the task it's doing.

PHP

$ ps faxv
  PID TTY      STAT   TIME  MAJFL   TRS   DRS   RSS %MEM COMMAND
13098 ?        Ss     0:00      0  5047 12668  2608  0.0 /usr/sbin/squid -a 3128 -f /etc/squid/squid.conf
13100 ?        S      0:01      5  5047 35240 25052  0.4  \_ (squid-1) -a 3128 -f /etc/squid/squid.conf
13101 ?        S      0:00      0     5  3942   992  0.0      \_ (logfile-daemon) /var/log/squid/access.log
13102 ?        S      0:00      1     2  3793   740  0.0      \_ (unlinkd)
13109 ?        S      0:00     50  3385 43962  7812  0.1      \_ /usr/bin/php /usr/local/bin/googlerewriter.php
13111 ?        S      0:00      0  3385 43962  7816  0.1      \_ /usr/bin/php /usr/local/bin/googlerewriter.php
13115 ?        S      0:00      0  3385 43962  7816  0.1      \_ /usr/bin/php /usr/local/bin/googlerewriter.php
13116 ?        S      0:00      0  3385 43962  7812  0.1      \_ /usr/bin/php /usr/local/bin/googlerewriter.php
13117 ?        S      0:00      0  3385 43962  7816  0.1      \_ /usr/bin/php /usr/local/bin/googlerewriter.php

$ top
  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
15552 squid     20   0 47348 7812 5428 S   0.0  0.1   0:00.05 googlerewriter.
15735 squid     20   0 47348 7816 5428 S   0.0  0.1   0:00.03 googlerewriter.
15736 squid     20   0 47348 7816 5428 S   0.0  0.1   0:00.03 googlerewriter.
15741 squid     20   0 47348 7816 5428 S   0.0  0.1   0:00.03 googlerewriter.

The resident set size of the Perl version is 31% that of the PHP version, or in other words the PHP version is using 3 times as much memory per process. By using the Perl version you'd save at least 5.2MiB. Not that this matters much on my current proxy server, but for an embedded server it would matter.

Perl

$ ps faxv
  PID TTY      STAT   TIME  MAJFL   TRS   DRS   RSS %MEM COMMAND
13382 ?        Ss     0:00      0  5047 12668  2608  0.0 /usr/sbin/squid -a 3128 -f /etc/squid/squid.conf
13384 ?        S      0:01      0  5047 37988 25308  0.4  \_ (squid-1) -a 3128 -f /etc/squid/squid.conf
13387 ?        S      0:00      0     5  3942   992  0.0      \_ (logfile-daemon) /var/log/squid/access.log
13388 ?        S      0:00      0     2  3793   740  0.0      \_ (unlinkd)
13396 ?        S      0:00      0     3  8700  2460  0.0      \_ /usr/bin/perl /usr/local/bin/googlerewriter.pl
13426 ?        S      0:00      0     3  8700  2376  0.0      \_ /usr/bin/perl /usr/local/bin/googlerewriter.pl
13427 ?        S      0:00      0     3  8700  2372  0.0      \_ /usr/bin/perl /usr/local/bin/googlerewriter.pl
13429 ?        S      0:00      0     3  8700  2460  0.0      \_ /usr/bin/perl /usr/local/bin/googlerewriter.pl
13430 ?        S      0:00      0     3  8700  2460  0.0      \_ /usr/bin/perl /usr/local/bin/googlerewriter.pl
13431 ?        S      0:00      0     3  8700  2460  0.0      \_ /usr/bin/perl /usr/local/bin/googlerewriter.pl

$ top
  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
13396 squid     20   0  8704 2460 1724 S   0.0  0.0   0:00.19 googlerewriter.
13429 squid     20   0  8704 2460 1724 S   0.0  0.0   0:00.03 googlerewriter.
13430 squid     20   0  8704 2460 1724 S   0.0  0.0   0:00.02 googlerewriter.
13431 squid     20   0  8704 2460 1724 S   0.0  0.0   0:00.02 googlerewriter.
13426 squid     20   0  8704 2376 1716 S   0.0  0.0   0:00.04 googlerewriter.
13427 squid     20   0  8704 2372 1716 S   0.0  0.0   0:00.03 googlerewriter.

Faster browsing aka Google Redirect Rewrite

Image courtesy of Open Clip Art Library

Once again I got annoyed by having to wait for Google to redirect me. I also think it's none of Google's business to know which sites I do visit especially if they can't be quick about it. So I decided to get rid of the delay.
I checked if there's a plugin for that and it seems there is. You can install Remove Google Redirects from Chrome Web Store. Being a paranoid weirdo like I am that still wasn't enough. I already had a Squid proxy that I had configured to make it so that you couldn't even know that some websites were blocked by my ISP(Sonera). It made sense to try and figure out if there was a trick that I could do with squid that allows me to get rid of the middle man(Google) in the redirect process.

And behold for the creators of Squid have indeed been so wise as to add a way to mangle the urls. All I had to do was to write a script that takes the url, checks if it's a google redirect url and if so, parses the url to get the actual url where we want to go and return that. The example on Squid feature page was a good place to start and this is what I came up with:

Perl Version

#!/usr/bin/perl

use URI;
use URI::QueryParam;

$|=1;
while (<>) {
    chomp;
    @X = split;
    $url = $X[1];
    #check if this is a google redirect url
    if ($url =~ /\/\/.*\.google\.[^\/]+\/url/) {
        my $uri = URI->new($url);
        $url = $uri->query_param("url");
        print $X[0]." 302:$url\n";
    } else {
        print $X[0]." \n";
    }
}

I had to install a couple of Perl modules while I was trying to refamiliarize myself with Perl so I wanted make a PHP version of the same helper. With PHP I wouldn't have to install any extra modules when some day I decide to use this on some other machine. I usually have PHP installed everywhere.

PHP Version

#!/usr/bin/php
<?php

function convertUrlQuery($query) {
    $queryParts = explode('&', $query);

    $params = array();
    foreach ($queryParts as $param) {
        $item = explode('=', $param);
        $params[$item[0]] = $item[1];
    }

    return $params;
}
while(1){
    $line = trim(fgets(STDIN)); // reads one line from STDIN
    $params = explode(" ", $line);
    $pattern = '/\/\/.*\.google\.[^\/]+\/url/';

    if (preg_match($pattern, $params[1], $matches, PREG_OFFSET_CAPTURE, 3)) {
        $parts = parse_url($params[1]);
        $query = convertUrlQuery($parts['query']);
        $url = urldecode($query['url']);
        echo $params[0]." 302:$url\n";
    } else {
        echo $params[0]." \n";
    }
}

In the end I like that with Perl I didn't have to write any functions for simple things like url parsing, but unless I package this as an installable package I could not just drop it in and expect it to work since I had to install the extra stuff as modules.(Yes I could have written my own implementation, but I'm not that much into reinventing the wheel. Also I was a bit impatient to get the script ready so I could see the results) With the PHP version I could just drop it in and as long as I had PHP installed it would work.

I strongly recommend adding a line in squid.conf It really makes a difference.

url_rewrite_program /path/to/googleredirectrewriter