open source this from falconpost.php

open sourcing get_rel_webmention and first_linknode_href functions because they are potentially useful to any PHP indieweb implementation, or anyone seeking to use the link rel parser functions.

Author: tantek

src/IndieWeb/get-rel-webmention.php

@@ -0,0 +1,112 @@
+<?php
+/* sample functions for using the link rel parser library to get first webmention (and pingback) endpoints */
+
+/* 
+first_linknode_href, get_rel_webmention by Tantek Çelik http://tantek.com/
+license: http://creativecommons.org/publicdomain/zero/1.0/
+*/
+
+function first_linknode_href($links, $spacedtagnames='a area link') {
+// in: DOMNodeList $links
+//     $spacedtagnames - space separated tag names, null for any
+// out: href attribute as string
+// return first DOMNode in $links that is an a, area, link with href
+// else return null
+  if ($spacedtagnames) {
+    $spacedtagnames = strcat(' ', $spacedtagnames, ' ');
+  }
+	foreach ($links as $link) {
+			if (!$spacedtagnames ||
+			    contains($spacedtagnames, 
+			             strcat(' ', $link->nodeName, ' '))) {
+			  return $link->getAttribute('href');
+			}
+	}
+	return null;
+}
+
+// in: $url of page that may or may not have a webmention endpoint
+// out: array of 'webmention' URL of webmention endpoint if any, 
+//           and 'pingback' URL of pingback endpoint if any
+function get_rel_webmention($url) {
+  global $debug;
+  $r = array();
+  $r['webmention'] = '';
+  $r['pingback'] = '';
+  
+  $httprels = head_http_rels($url);
+  if ($debug) {
+    echo 'head_http_rels STATUS:"'.$httprels['status'].'"<br/>';
+  }
+  if ($httprels['status'] != "200") {
+    return $r;
+  }
+  
+  if ($debug) {
+    echo 'HEAD Content-Type: '.$httprels['type'].' '.
+         string(is_html_type($httprels['type'])).'<br/>';
+  }
+  $wm = '';
+  $pb = '';
+  if (array_key_exists('webmention', $httprels['rels'])) {
+    $wm = $httprels['rels']['webmention'][0];
+    // just use the first one.
+  }
+  if (array_key_exists('pingback', $httprels['rels'])) {
+    $pb = $httprels['rels']['pingback'][0];
+    // just use the first one.
+  }
+  if ($debug && $wm) {
+    echo "HEAD LINK webmention: '$wm'<br/>";
+  }
+  if ($debug && $pb) {
+    echo "HEAD LINK pingback: '$pb'<br/>";
+  }
+  if (!$wm && is_html_type($httprels['type'])) {
+    // no webmention endpoint in HTTP headers, check HTML
+    if ($debug) {
+      echo "looking for wm endpoint in HTML $url<br/>";
+    }
+    $ch = curl_init($url);
+//  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
+// commented out due to:
+// Warning: curl_setopt(): CURLOPT_FOLLOWLOCATION cannot be activated when an open_basedir is set
+	  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+    $s = curl_exec($ch);
+    curl_close($ch);
+    if ($s != '') {
+      $dom = new DOMDocument();
+      $dom->loadHTML($s); // ** maybe only load part of it?
+      $domx = new DOMXPath($dom);
+      $wms = $domx->query(xphasrel('webmention'));
+      if ($wms) { $wms = first_linknode_href($wms); }
+      if ($debug) {
+        echo "query xphasrel webmention $wms<br/>";
+      }
+
+      if ($wms !== null) {
+        $wm = get_absolute_uri($wms, $url);
+      }
+      if ($debug && $wm) {
+        echo "HTML rel=webmention returned '$wm'<br/>";
+      }
+      $wms = $domx->query(xphasrel('pingback'));
+      if ($wms) { $wms = first_linknode_href($wms, 'link'); }
+      if ($debug) {
+        echo "query xphasrel pingback $wms<br/>";
+      }
+
+      if ($wms !== null) {
+        $pb = get_absolute_uri($wms, $url);
+      }
+      if ($debug && $pb) {
+        echo "HTML rel=pingback returned '$pb'<br/>";
+      }
+    }
+  }
+  $r['webmention'] = $wm;
+  $r['pingback'] = $pb;
+  return $r;
+}
+
+?>