問題描述
發出原始 HTTP 請求時如何輕鬆解碼 HTTP 分塊編碼字符串？ (How to easily decode HTTP-chunked encoded string when making raw HTTP request?)
I want to make HTTP request without having dependency to cURL and allow_url_fopen = 1 by opening socket connection and send raw HTTP request:
/**
* Make HTTP GET request
*
* @param string the URL
* @param int will be filled with HTTP response status code
* @param string will be filled with HTTP response header
* @return string HTTP response body
*/
function http_get_request($url, &$http_code = '', &$res_head = '')
{
$scheme = $host = $user = $pass = $query = $fragment = '';
$path = '/';
$port = substr($url, 0, 5) == 'https' ? 443 : 80;
extract(parse_url($url));
$path .= ($query ? "?$query" : '').($fragment ? "#$fragment" : '');
$head = "GET $path HTTP/1.1\r\n"
. "Host: $host\r\n"
. "Authorization: Basic ".base64_encode("$user:$pass")."\r\n"
. "Connection: close\r\n\r\n";
$fp = fsockopen($scheme == 'https' ? "ssl://$host" : $host, $port) or
die('Cannot connect!');
fputs($fp, $head);
while(!feof($fp)) {
$res .= fgets($fp, 4096);
}
fclose($fp);
list($res_head, $res_body) = explode("\r\n\r\n", $res, 2);
list(, $http_code, ) = explode(' ', $res_head, 3);
return $res_body;
}
The function works ok, but since I'm using HTTP/1.1, the response body usually returned in Chunked-encoded string. For example (from Wikipedia):
25
This is the data in the first chunk
1C
and this is the second one
3
con
8
sequence
0
I don't want to use http_chunked_decode() since it has PECL dependency and I want a highly portable code.
How to easily decode HTTP-chunked encoded string so my function can return the original HTML? I also have to make sure that the length of the decoded string match with the Content-Length: header.
Any help would be appreciated. Thanks.
參考解法
方法 1:
Since the function returns the HTTP response header, you should check if 'Transfer-Encoding' is 'chunked' then decode the chunked-encoded string. In pseudocode:
CALL parse_http_header
IF 'Transfer-Encoding' IS 'chunked'
CALL decode_chunked
Parsing HTTP response header:
Below is the function to parse HTTP response header to associative array.
function parse_http_header($str)
{
$lines = explode("\r\n", $str);
$head = array(array_shift($lines));
foreach ($lines as $line) {
list($key, $val) = explode(':', $line, 2);
if ($key == 'Set-Cookie') {
$head['Set-Cookie'][] = trim($val);
} else {
$head[$key] = trim($val);
}
}
return $head;
}
The function will return an array like this:
Array
(
[0] => HTTP/1.1 200 OK
[Expires] => Tue, 31 Mar 1981 05:00:00 GMT
[Content-Type] => text/html; charset=utf-8
[Transfer-Encoding] => chunked
[Set-Cookie] => Array
(
[0] => k=10.34; path=/; expires=Sat, 09-Jun-12 01:58:23 GMT; domain=.example.com
[1] => guest_id=v1%3A13; domain=.example.com; path=/; expires=Mon, 02-Jun-2014 13:58:23 GMT
)
[Content-Length] => 43560
)
Notice how the Set-Cookie headers parsed to array. You need to parse the cookies later to associate a URL with the cookies need to be sent.
Decode the chunked-encoded string
The function below take the chunked-encoded string as the argument, and return the decoded string.
function decode_chunked($str) {
for ($res = ''; !empty($str); $str = trim($str)) {
$pos = strpos($str, "\r\n");
$len = hexdec(substr($str, 0, $pos));
$res.= substr($str, $pos + 2, $len);
$str = substr($str, $pos + 2 + $len);
}
return $res;
}
// Given the string in the question, the function above will returns:
//
// This is the data in the first chunk
// and this is the second one
// consequence
方法 2:
I don't know if it's optimal for you what you need to do but, if you specify HTTP/1.0 instead of HTTP/1.1, you will not get a chunked response.
方法 3:
this Function use in Wordpress.
function decode_chunked($data) {
if (!preg_match('/^([0-9a-f]+)(?:;(?:[\w-]*)(?:=(?:(?:[\w-]*)*|"(?:[^\r\n])*"))?)*\r\n/i', trim($data))) {
return $data;
}
$decoded = '';
$encoded = $data;
while (true) {
$is_chunked = (bool) preg_match('/^([0-9a-f]+)(?:;(?:[\w-]*)(?:=(?:(?:[\w-]*)*|"(?:[^\r\n])*"))?)*\r\n/i', $encoded, $matches);
if (!$is_chunked) {
// Looks like it's not chunked after all
return $data;
}
$length = hexdec(trim($matches[1]));
if ($length === 0) {
// Ignore trailer headers
return $decoded;
}
$chunk_length = strlen($matches[0]);
$decoded .= substr($encoded, $chunk_length, $length);
$encoded = substr($encoded, $chunk_length + $length + 2);
if (trim($encoded) === '0' || empty($encoded)) {
return $decoded;
}
}
// We'll never actually get down here
// @codeCoverageIgnoreStart
}
(by flowfree、flowfree、Okonomiyaki3000、user3770797)