Converting relative URL to absolute - php

Question

Let's say I have a URL of the document linking to another document (which can be both absolute or relative) and I need to have this link in absolute.
I made the simple function providing this functionality for several common cases:
function absolute_url($url,$parent_url){
$parent_url=parse_url($parent_url);
if(strcmp(substr($url,0,7),'http://')==0){
return $url;
}
elseif(strcmp(substr($url,0,1),'/')==0){
return $parent_url['scheme']."://".$parent_url['host'].$url;
}
else{
$path=$parent_url['path'];
$path=substr($path,0,strrpos($path,'/'));
return $parent_url['scheme']."://".$parent_url['host']."$path/".$url;
}
}
$parent_url='http://example.com/path/to/file/name.php?abc=abc';
echo absolute_url('name2.php',$parent_url)."\n";
// output http://example.com/path/to/file/name2.php
echo absolute_url('/name2.php',$parent_url)."\n";
// output http://example.com/name2.php
echo absolute_url('http://name2.php',$parent_url)."\n";
// output http://name2.php
The code works fine, but there could be more cases such as ../../path/to/file.php which will not work.
So is there any standard classes or function doing this thing better (more universal) that my function?
I tried to Google it and check the similar questions (one and two) but it looks like server-path related solution which is not the thing I'm looking for.

Answer 1

This function will resolve relative URLs to a given current page url in $pgurl without regex. It successfully resolves:
/home.php?example types,
same-dir nextpage.php types,
../...../.../parentdir types,
full http://example.net urls,
and shorthand //example.net urls
//Current base URL (you can dynamically retrieve from $_SERVER)
$pgurl = 'http://example.com/scripts/php/absurl.php';
function absurl($url) {
global $pgurl;
if(strpos($url,'://')) return $url; //already absolute
if(substr($url,0,2)=='//') return 'http:'.$url; //shorthand scheme
if($url[0]=='/') return parse_url($pgurl,PHP_URL_SCHEME).'://'.parse_url($pgurl,PHP_URL_HOST).$url; //just add domain
if(strpos($pgurl,'/',9)===false) $pgurl .= '/'; //add slash to domain if needed
return substr($pgurl,0,strrpos($pgurl,'/')+1).$url; //for relative links, gets current directory and appends new filename
}
function nodots($path) { //Resolve dot dot slashes, no regex!
$arr1 = explode('/',$path);
$arr2 = array();
foreach($arr1 as $seg) {
switch($seg) {
case '.':
break;
case '..':
array_pop($arr2);
break;
case '...':
array_pop($arr2); array_pop($arr2);
break;
case '....':
array_pop($arr2); array_pop($arr2); array_pop($arr2);
break;
case '.....':
array_pop($arr2); array_pop($arr2); array_pop($arr2); array_pop($arr2);
break;
default:
$arr2[] = $seg;
}
}
return implode('/',$arr2);
}
Usage Example:
echo nodots(absurl('../index.html'));
nodots() must be called after the URL is converted to absolute.
The dots function is kind of redundant, but is readable, fast, doesn't use regex's, and will resolve 99% of typical urls (if you want to be 100% sure, just extend the switch block to support 6+ dots, although I've never seen that many dots in a URL).
Hope this helps,

Answer 2

$uri = "..";
$path = realpath($uri);
$root = realpath($_SERVER["DOCUMENT_ROOT"]);
if($path){
$path = str_replace($root, "", $path);
$path = $_SERVER["SERVER_NAME"] . $path;
$protocol = "http";
if(isset($_SERVER["HTTPS"])){
$protocol .= "s";
}
$path = "{$protocol}://$path";
$path = str_replace("\\", "/", $path);
}
var_dump($path);
There is probably a better/quicker way, but I just knocked this up...

Answer 3

A web browser uses the page URL or the base tag to resolve relative URLs.
This script can resolve a URL or URI relative to a base URL. The URL or URI is resolved in the common way used by browsers.
/** Build a URL
*
* #param array $parts An array that follows the parse_url scheme
* #return string
*/
function build_url($parts)
{
if (empty($parts['user'])) {
$url = $parts['scheme'] . '://' . $parts['host'];
} elseif(empty($parts['pass'])) {
$url = $parts['scheme'] . '://' . $parts['user'] . '#' . $parts['host'];
} else {
$url = $parts['scheme'] . '://' . $parts['user'] . ':' . $parts['pass'] . '#' . $parts['host'];
}
if (!empty($parts['port'])) {
$url .= ':' . $parts['port'];
}
if (!empty($parts['path'])) {
$url .= $parts['path'];
}
if (!empty($parts['query'])) {
$url .= '?' . $parts['query'];
}
if (!empty($parts['fragment'])) {
return $url . '#' . $parts['fragment'];
}
return $url;
}
/** Convert a relative path into an absolute path
*
* #param string $path
* #return string
*/
function abs_path($path)
{
$path_array = explode('/', $path);
// Solve current and parent folder navigation
$translated_path_array = array();
$i = 0;
foreach ($path_array as $name) {
if ($name === '..') {
unset($translated_path_array[--$i]);
} elseif (!empty($name) && $name !== '.') {
$translated_path_array[$i++] = $name;
}
}
return '/' . implode('/', $translated_path_array);
}
/** Convert a relative URL in to an absolute URL
*
* #param string $url URL or URI
* #param string $base Absolute URL
* #return string
*/
function abs_url($url, $base)
{
$url_parts = parse_url($url);
$base_parts = parse_url($base);
// Handle the path if it is specified
if (!empty($url_parts['path'])) {
// Is the path relative
if (substr($url_parts['path'], 0, 1) !== '/') {
// Does the base path end with slash?
if (substr($base_parts['path'], -1) === '/') {
$url_parts['path'] = $base_parts['path'] . $url_parts['path'];
} else {
$url_parts['path'] = dirname($base_parts['path']) . '/' . $url_parts['path'];
}
}
// Make path absolute
$url_parts['path'] = abs_path($url_parts['path']);
}
// Use the base URL to populate the unfilled components until a component is filled
foreach (['scheme', 'host', 'path', 'query', 'fragment'] as $comp) {
if (!empty($url_parts[$comp])) {
break;
}
$url_parts[$comp] = $base_parts[$comp];
}
return build_url($url_parts);
}
Test
// Base URL
$base_url = 'https://example.com/path1/path2/path3/path4/file.ext?field1=value1&field2=value2#fragment';
// URL and URIs (_ is used to see what is coming from relative URL)
$test_urls = array(
"http://_example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment", // URL
"//_example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment", // URI without scheme
"//_example.com", // URI with host only
"/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment", // URI without scheme and host
"_path1/_path2/_file.ext", // URI with path only
"./../../_path1/../_path2/file.ext#_fragment", // URI with path and fragment
"?_field1=_value1&_field2=_value2#_fragment", // URI with query and fragment
"#_fragment" // URI with fragment only
);
// Expected result
$expected_urls = array(
"http://_example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment",
"https://_example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment",
"https://_example.com",
"https://example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment",
"https://example.com/path1/path2/path3/path4/_path1/_path2/_file.ext",
"https://example.com/path1/path2/_path2/file.ext#_fragment",
"https://example.com/path1/path2/path3/path4/file.ext?_field1=_value1&_field2=_value2#_fragment",
"https://example.com/path1/path2/path3/path4/file.ext?field1=value1&field2=value2#_fragment"
);
foreach ($test_urls as $i => $url) {
$abs_url = abs_url($url, $base_url);
if ( $abs_url == $expected_urls[$i] ) {
echo "[OK] " . $abs_url . PHP_EOL;
} else {
echo "[WRONG] " . $abs_url . PHP_EOL;
}
}
Result
[OK] http://_example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment
[OK] https://_example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment
[OK] https://_example.com
[OK] https://example.com/_path1/_path2/_file.ext?_field1=_value1&_field2=_value2#_fragment
[OK] https://example.com/path1/path2/path3/path4/_path1/_path2/_file.ext
[OK] https://example.com/path1/path2/_path2/file.ext#_fragment
[OK] https://example.com/path1/path2/path3/path4/file.ext?_field1=_value1&_field2=_value2#_fragment
[OK] https://example.com/path1/path2/path3/path4/file.ext?field1=value1&field2=value2#_fragment