Regex for parsing http request

Question

I am trying to parse the HTTP request with the following code:

$request="GET /index.html HTTP/1.1";
$methods="GET|HEAD|TRACE|OPTIONS";
$pattern="/(^".$methods.")\s+(\S+)\s+(HTTP)/";
list($method,$uri,$http)=preg_split($pattern,$request);
print $method.$uri.$http;

Print does not return anything. I tried different modifications,but wasn't able to. I think the problem is with the regex. Any help is appreciated.

Michael Berkowski · Accepted Answer · 2012-01-26 03:02:30Z

5

Instead of preg_split(), you may want to use preg_match(), and move the ^ outside the parens.

$request="GET /index.html HTTP/1.1";
$methods="GET|HEAD|TRACE|OPTIONS";
$pattern="/^(".$methods.")\s+(\S+)\s+(HTTP)/";
//-------^^^^

$matches = array();
preg_match($pattern, $request, $matches);
print_r($matches);

// To get it back to the form you wanted...
array_shift($matches);
list($method, $uri, $http) = $matches;

answered Jan 26, 2012 at 3:02

Michael Berkowski

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2 Comments

Borodin Over a year ago

It doesn't matter whether the ^ is inside or outside the parentheses: it is a zero-width match and won't affect the result.

Julian Reschke Over a year ago

Don't put the method names into the regexp; there are more methods than these.

Borodin · Accepted Answer · 2012-01-26 03:17:07Z

1

It would be simpler to simply split the request on whitespace.

list($method, $uri, $http) = preg_split('/\s+/', $request);

will produce the same result, except that $http will be HTTP/1.1 which may or may not be what you want in the first place.

answered Jan 26, 2012 at 3:17

Borodin

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