aaronpk · August 19, 2018 21:51 · Aug 19, 2018 · Aug 19, 2018
diff --git a/is_valid_mf2_json.php b/is_valid_mf2_json.php
@@ -0,0 +1,35 @@
+<?php
+
+function is_valid_mf2_json($input) {
+	// Input to this function must be an array
+	if(!is_array($input))
+		return false;
+
+	// Keys type and properties are required at a minimum and must be arrays
+	if(!isset($input['type']) || !is_array($input['type']))
+		return false;
+	if(!isset($input['properties']) || !is_array($input['properties']))
+		return false;
+
+	// Every value of type must be a string beginning with h-
+	foreach($input['type'] as $type) {
+		if(!is_string($type) || substr($type, 0, 2) != 'h-')
+			return false;
+	}
+
+	foreach($input['properties'] as $property) {
+		// Every property must be an array
+		if(!is_array($property))
+			return false;
+
+		// If a value of a property is not a string, it must be a valid mf2 object
+		foreach($property as $val) {
+			if(!is_string($val)) {
+				if(!is_valid_mf2_json($val))
+					return false;
+			}
+		}
+	}
+
+	return true;
+}