PHP: How to resolve a relative url - php

Question

I need a function that given a relative URL and a base returns an absolute URL. I've searched and found many functions that do it different ways.
resolve("../abc.png", "http://example.com/path/thing?foo=bar")
# returns http://example.com/abc.png
Is there a canonical way?
On this site I see great examples for python and c#, lets get a PHP solution.

Answer 1

Perhaps this article could help?
http:// nashruddin.com/PHP_Script_for_Converting_Relative_to_Absolute_URL
Edit: reproduced code below for convenience
<?php
function rel2abs($rel, $base)
{
/* return if already absolute URL */
if (parse_url($rel, PHP_URL_SCHEME) != '' || substr($rel, 0, 2) == '//') return $rel;
/* queries and anchors */
if ($rel[0]=='#' || $rel[0]=='?') return $base.$rel;
/* parse base URL and convert to local variables:
$scheme, $host, $path */
extract(parse_url($base));
/* remove non-directory element from path */
$path = preg_replace('#/[^/]*$#', '', $path);
/* destroy path if relative url points to root */
if ($rel[0] == '/') $path = '';
/* dirty absolute URL */
$abs = "$host$path/$rel";
/* replace '//' or '/./' or '/foo/../' with '/' */
$re = array('#(/\.?/)#', '#/(?!\.\.)[^/]+/\.\./#');
for($n=1; $n>0; $abs=preg_replace($re, '/', $abs, -1, $n)) {}
/* absolute URL is ready! */
return $scheme.'://'.$abs;
}
?>

Answer 2

Another solution in case you already use GuzzleHttp.
This solution is based on an internal method of GuzzleHttp\Client.
use GuzzleHttp\Psr7\UriResolver;
use GuzzleHttp\Psr7\Utils;
function resolve(string $uri, ?string $base_uri): string
{
$uri = Utils::uriFor(trim($uri));
if (isset($base_uri)) {
$uri = UriResolver::resolve(Utils::uriFor(trim($base_uri)), $uri);
}
// optional: set default scheme if missing
$uri = $uri->getScheme() === '' && $uri->getHost() !== '' ? $uri->withScheme('http') : $uri;
return (string)$uri;
}
EDIT: the source code was updated as suggested by myriacl

Answer 3

If your have pecl-http, you can use http://php.net/manual/en/function.http-build-url.php
<?php
$url_parts = parse_url($relative_url);
$absolute = http_build_url($source_url, $url_parts, HTTP_URL_JOIN_PATH);
Ex:
<?php
function getAbsoluteURL($source_url, $relative_url)
{
$url_parts = parse_url($relative_url);
return http_build_url($source_url, $url_parts, HTTP_URL_JOIN_PATH);
}
echo getAbsoluteURL('http://foo.tw/a/b/c', '../pic.jpg') . "\n";
// http://foo.tw/a/pic.jpg
echo getAbsoluteURL('http://foo.tw/a/b/c/', '../pic.jpg') . "\n";
// http://foo.tw/a/b/pic.jpg
echo getAbsoluteURL('http://foo.tw/a/b/c/', 'http://bar.tw/a.js') . "\n";
// http://bar.tw/a.js
echo getAbsoluteURL('http://foo.tw/a/b/c/', '/robots.txt') . "\n";
// http://foo.tw/robots.txt

Answer 4

other tools that are already linked in page linked in pguardiario's comment: http://publicmind.in/blog/urltoabsolute/ , https://github.com/monkeysuffrage/phpuri .
and i have found other tool from comment in http://nadeausoftware.com/articles/2008/05/php_tip_how_convert_relative_url_absolute_url :
require_once 'Net/URL2.php';
$base = new Net_URL2('http://example.org/foo.html');
$absolute = (string)$base->resolve('relative.html#bar');

Answer 5

Here is another function that can handle protocol relative urls
<?php
function getAbsoluteURL($to, $from = null) {
$arTarget = parse_url($to);
$arSource = parse_url($from);
$targetPath = isset($arTarget['path']) ? $arTarget['path'] : '';
if (isset($arTarget['host'])) {
if (!isset($arTarget['scheme'])) {
$proto = isset($arSource['scheme']) ? "{$arSource['scheme']}://" : '//';
} else {
$proto = "{$arTarget['scheme']}://";
}
$baseUrl = "{$proto}{$arTarget['host']}" . (isset($arTarget['port']) ? ":{$arTarget['port']}" : '');
} else {
if (isset($arSource['host'])) {
$proto = isset($arSource['scheme']) ? "{$arSource['scheme']}://" : '//';
$baseUrl = "{$proto}{$arSource['host']}" . (isset($arSource['port']) ? ":{$arSource['port']}" : '');
} else {
$baseUrl = '';
}
$arPath = [];
if ((empty($targetPath) || $targetPath[0] !== '/') && !empty($arSource['path'])) {
$arTargetPath = explode('/', $targetPath);
if (empty($arSource['path'])) {
$arPath = [];
} else {
$arPath = explode('/', $arSource['path']);
array_pop($arPath);
}
$len = count($arPath);
foreach ($arTargetPath as $idx => $component) {
if ($component === '..') {
if ($len > 1) {
$len--;
array_pop($arPath);
}
} elseif ($component !== '.') {
$len++;
array_push($arPath, $component);
}
}
$targetPath = implode('/', $arPath);
}
}
return $baseUrl . $targetPath;
}
// SAMPLES
// Absolute path => https://www.google.com/doubleclick/
echo getAbsoluteURL('/doubleclick/', 'https://www.google.com/doubleclick/insights/') . "\n";
// Relative path 1 => https://www.google.com/doubleclick/studio
echo getAbsoluteURL('../studio', 'https://www.google.com/doubleclick/insights/') . "\n";
// Relative path 2 => https://www.google.com/doubleclick/insights/case-studies.html
echo getAbsoluteURL('./case-studies.html', 'https://www.google.com/doubleclick/insights/') . "\n";
// Relative path 3 => https://www.google.com/doubleclick/insights/case-studies.html
echo getAbsoluteURL('case-studies.html', 'https://www.google.com/doubleclick/insights/') . "\n";
// Protocol relative url => https://www.google.com/doubleclick/
echo getAbsoluteURL('//www.google.com/doubleclick/', 'https://www.google.com/doubleclick/insights/') . "\n";
// Empty path => https://www.google.com/doubleclick/insights/
echo getAbsoluteURL('', 'https://www.google.com/doubleclick/insights/') . "\n";
// Different url => http://www.yahoo.com/
echo getAbsoluteURL('http://www.yahoo.com/', 'https://www.google.com') . "\n";

Answer 6

function absoluteUri($Path, $URI)
{ # Requires PHP4 or better.
$URL = parse_url($URI);
$Str = "{$URL['scheme']}://";
if (isset($URL['user']) || isset($URL['pass']))
$Str .= "{$URL['user']}:{$URL['pass']}#";
$Str .= $URL['host'];
if (isset($URL['port']))
$Str .= ":{$URL['port']}";
$Str .= realpath($URL['path'] . $Path); # This part might have an issue on windows boxes.
if (isset($URL['query']))
$Str .= "?{$URL['query']}";
if (isset($URL['fragment']))
$Str .= "#{$URL['fragment']}";
return $Str;
}
absoluteUri("../abc.png", "http://example.com/path/thing?foo=bar");
# Should return "http://example.com/abc.png?foo=bar" on Linux boxes.

Answer 7

I noticed the upvoted answer above uses RegEx, which can be dangerous when dealing with URLs.
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,