implement http_rels and head_http_rels

Author: tantek

src/IndieWeb/link_rel_parser.php

@@ -1,11 +1,76 @@
 <?php
 namespace IndieWeb;
 
-function http_rels($headerString) {
+/* 
+http_rels, head_http_rels by Tantek Çelik http://tantek.com/
+license: http://creativecommons.org/publicdomain/zero/1.0/
+*/
 
-  // TODO: Implement this
+// in $h: HTTP headers as a string
+// returns: array of rel values as indices to arrays of URLs
+function http_rels($h) {
+  $h = explode("\r\n", preg_replace("/(\r\n|\r|\n)[ \t]+/", " ", $h));
+  $rels = array();
+  foreach ($h as $f) {
+    if (!strncmp($f, 'X-Pingback: ', 12)) {
+      // convert to a link header and have common code handle it
+      $f = 'Link: <' . trim(substr($f, 12)) . '>; rel="pingback"';
+    }
+    if (!strncmp($f, 'Link: ', 6)) {
+      $links = explode(', ', trim(substr($f, 6)));
+      foreach ($links as $link) {
+        $hrefandrel = explode('; ', $link);
+        $href = trim($hrefandrel[0], '<>');
+        $relarray = '';
+        foreach ($hrefandrel as $p) {
+          if (!strncmp($p, 'rel=', 4)) {
+            $relarray = explode(' ', trim(substr($p, 4), '"\''));
+            break;
+          }
+        }
+        if ($relarray !== '') { // ignore Link: headers without rel
+          foreach ($relarray as $rel) {
+            $rel = strtolower(trim($rel));
+            if ($rel != '') {
+              if (!$rels[$rel]) { 
+                $rels[$rel] = array(); 
+              }
+              if (!in_array($href, $rels[$rel])) {
+                $rels[$rel][] = $href;
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+  return $rels;
+}
+
+// in $url: URL to get HTTP HEAD Link (and effective/x-extended) rels 
+// returns: array of 
+//        "status"=> HTTP status code, 
+//        "rels" array with 
+function head_http_rels($url) {
+	$c = curl_init();
+	curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);
+	curl_setopt($c, CURLOPT_URL, $url);
+	curl_setopt($c, CURLOPT_CONNECTTIMEOUT, 2);
+	curl_setopt($c, CURLOPT_TIMEOUT, 4);
+	curl_setopt($c, CURLOPT_USERAGENT, 'head_http_rels function');
+	curl_setopt($c, CURLOPT_FOLLOWLOCATION, 1);
+  curl_setopt($c, CURLOPT_SSL_VERIFYPEER , false );
+  curl_setopt($c, CURLOPT_SSL_VERIFYHOST , false );
+  curl_setopt($c, CURLOPT_HEADER, true);
+  curl_setopt($c, CURLOPT_NOBODY, true);
+  $h = curl_exec($c);
+	$i = curl_getinfo($c);
+  curl_close($c);
+  unset($c);
 
-  return array(
-    'rels' => array()
-  );
+  $r = array();
+  $r['status'] = $i['http_code'];
+  $r['rels'] = http_rels($h);
+  return $r;
 }
+?>