1<?php 2 3declare(strict_types=1); 4 5namespace GuzzleHttp\Psr7; 6 7use Psr\Http\Message\UriInterface; 8 9/** 10 * Resolves a URI reference in the context of a base URI and the opposite way. 11 * 12 * @author Tobias Schultze 13 * 14 * @see https://datatracker.ietf.org/doc/html/rfc3986#section-5 15 */ 16final class UriResolver 17{ 18 /** 19 * Removes dot segments from a path and returns the new path. 20 * 21 * @see https://datatracker.ietf.org/doc/html/rfc3986#section-5.2.4 22 */ 23 public static function removeDotSegments(string $path): string 24 { 25 if ($path === '' || $path === '/') { 26 return $path; 27 } 28 29 $results = []; 30 $segments = explode('/', $path); 31 foreach ($segments as $segment) { 32 if ($segment === '..') { 33 array_pop($results); 34 } elseif ($segment !== '.') { 35 $results[] = $segment; 36 } 37 } 38 39 $newPath = implode('/', $results); 40 41 if ($path[0] === '/' && (!isset($newPath[0]) || $newPath[0] !== '/')) { 42 // Re-add the leading slash if necessary for cases like "/.." 43 $newPath = '/'.$newPath; 44 } elseif ($newPath !== '' && ($segment === '.' || $segment === '..')) { 45 // Add the trailing slash if necessary 46 // If newPath is not empty, then $segment must be set and is the last segment from the foreach 47 $newPath .= '/'; 48 } 49 50 return $newPath; 51 } 52 53 /** 54 * Converts the relative URI into a new URI that is resolved against the base URI. 55 * 56 * @see https://datatracker.ietf.org/doc/html/rfc3986#section-5.2 57 */ 58 public static function resolve(UriInterface $base, UriInterface $rel): UriInterface 59 { 60 if ((string) $rel === '') { 61 // we can simply return the same base URI instance for this same-document reference 62 return $base; 63 } 64 65 if ($rel->getScheme() != '') { 66 return $rel->withPath(self::removeDotSegments($rel->getPath())); 67 } 68 69 if ($rel->getAuthority() != '') { 70 $targetAuthority = $rel->getAuthority(); 71 $targetPath = self::removeDotSegments($rel->getPath()); 72 $targetQuery = $rel->getQuery(); 73 } else { 74 $targetAuthority = $base->getAuthority(); 75 if ($rel->getPath() === '') { 76 $targetPath = $base->getPath(); 77 $targetQuery = $rel->getQuery() != '' ? $rel->getQuery() : $base->getQuery(); 78 } else { 79 if ($rel->getPath()[0] === '/') { 80 $targetPath = $rel->getPath(); 81 } else { 82 if ($targetAuthority != '' && $base->getPath() === '') { 83 $targetPath = '/'.$rel->getPath(); 84 } else { 85 $lastSlashPos = strrpos($base->getPath(), '/'); 86 if ($lastSlashPos === false) { 87 $targetPath = $rel->getPath(); 88 } else { 89 $targetPath = substr($base->getPath(), 0, $lastSlashPos + 1).$rel->getPath(); 90 } 91 } 92 } 93 $targetPath = self::removeDotSegments($targetPath); 94 $targetQuery = $rel->getQuery(); 95 } 96 } 97 98 return new Uri(Uri::composeComponents( 99 $base->getScheme(), 100 $targetAuthority, 101 $targetPath, 102 $targetQuery, 103 $rel->getFragment() 104 )); 105 } 106 107 /** 108 * Returns the target URI as a relative reference from the base URI. 109 * 110 * This method is the counterpart to resolve(): 111 * 112 * (string) $target === (string) UriResolver::resolve($base, UriResolver::relativize($base, $target)) 113 * 114 * One use-case is to use the current request URI as base URI and then generate relative links in your documents 115 * to reduce the document size or offer self-contained downloadable document archives. 116 * 117 * $base = new Uri('http://example.com/a/b/'); 118 * echo UriResolver::relativize($base, new Uri('http://example.com/a/b/c')); // prints 'c'. 119 * echo UriResolver::relativize($base, new Uri('http://example.com/a/x/y')); // prints '../x/y'. 120 * echo UriResolver::relativize($base, new Uri('http://example.com/a/b/?q')); // prints '?q'. 121 * echo UriResolver::relativize($base, new Uri('http://example.org/a/b/')); // prints '//example.org/a/b/'. 122 * 123 * This method also accepts a target that is already relative and will try to relativize it further. Only a 124 * relative-path reference will be returned as-is. 125 * 126 * echo UriResolver::relativize($base, new Uri('/a/b/c')); // prints 'c' as well 127 */ 128 public static function relativize(UriInterface $base, UriInterface $target): UriInterface 129 { 130 if ($target->getScheme() !== '' 131 && ($base->getScheme() !== $target->getScheme() || $target->getAuthority() === '' && $base->getAuthority() !== '') 132 ) { 133 return $target; 134 } 135 136 if (Uri::isRelativePathReference($target)) { 137 // As the target is already highly relative we return it as-is. It would be possible to resolve 138 // the target with `$target = self::resolve($base, $target);` and then try make it more relative 139 // by removing a duplicate query. But let's not do that automatically. 140 return $target; 141 } 142 143 if ($target->getAuthority() !== '' && $base->getAuthority() !== $target->getAuthority()) { 144 return $target->withScheme(''); 145 } 146 147 // We must remove the path before removing the authority because if the path starts with two slashes, the URI 148 // would turn invalid. And we also cannot set a relative path before removing the authority, as that is also 149 // invalid. 150 $emptyPathUri = $target->withScheme('')->withPath('')->withUserInfo('')->withPort(null)->withHost(''); 151 152 if ($base->getPath() !== $target->getPath()) { 153 return $emptyPathUri->withPath(self::getRelativePath($base, $target)); 154 } 155 156 if ($base->getQuery() === $target->getQuery()) { 157 // Only the target fragment is left. And it must be returned even if base and target fragment are the same. 158 return $emptyPathUri->withQuery(''); 159 } 160 161 // If the base URI has a query but the target has none, we cannot return an empty path reference as it would 162 // inherit the base query component when resolving. 163 if ($target->getQuery() === '') { 164 $segments = explode('/', $target->getPath()); 165 /** @var string $lastSegment */ 166 $lastSegment = end($segments); 167 168 return $emptyPathUri->withPath($lastSegment === '' ? './' : $lastSegment); 169 } 170 171 return $emptyPathUri; 172 } 173 174 private static function getRelativePath(UriInterface $base, UriInterface $target): string 175 { 176 $sourceSegments = explode('/', $base->getPath()); 177 $targetSegments = explode('/', $target->getPath()); 178 array_pop($sourceSegments); 179 $targetLastSegment = array_pop($targetSegments); 180 foreach ($sourceSegments as $i => $segment) { 181 if (isset($targetSegments[$i]) && $segment === $targetSegments[$i]) { 182 unset($sourceSegments[$i], $targetSegments[$i]); 183 } else { 184 break; 185 } 186 } 187 $targetSegments[] = $targetLastSegment; 188 $relativePath = str_repeat('../', count($sourceSegments)).implode('/', $targetSegments); 189 190 // A reference to am empty last segment or an empty first sub-segment must be prefixed with "./". 191 // This also applies to a segment with a colon character (e.g., "file:colon") that cannot be used 192 // as the first segment of a relative-path reference, as it would be mistaken for a scheme name. 193 if ('' === $relativePath || false !== strpos(explode('/', $relativePath, 2)[0], ':')) { 194 $relativePath = "./$relativePath"; 195 } elseif ('/' === $relativePath[0]) { 196 if ($base->getAuthority() != '' && $base->getPath() === '') { 197 // In this case an extra slash is added by resolve() automatically. So we must not add one here. 198 $relativePath = ".$relativePath"; 199 } else { 200 $relativePath = "./$relativePath"; 201 } 202 } 203 204 return $relativePath; 205 } 206 207 private function __construct() 208 { 209 // cannot be instantiated 210 } 211} 212