First implementation

vendor/github.com/eclipse/paho.mqtt.golang/topic.go

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2014 IBM Corp.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Seth Hoenig
+ *    Allan Stockdill-Mander
+ *    Mike Robertson
+ */
+
+package mqtt
+
+import (
+	"errors"
+	"strings"
+)
+
+//ErrInvalidQos is the error returned when an packet is to be sent
+//with an invalid Qos value
+var ErrInvalidQos = errors.New("Invalid QoS")
+
+//ErrInvalidTopicEmptyString is the error returned when a topic string
+//is passed in that is 0 length
+var ErrInvalidTopicEmptyString = errors.New("Invalid Topic; empty string")
+
+//ErrInvalidTopicMultilevel is the error returned when a topic string
+//is passed in that has the multi level wildcard in any position but
+//the last
+var ErrInvalidTopicMultilevel = errors.New("Invalid Topic; multi-level wildcard must be last level")
+
+// Topic Names and Topic Filters
+// The MQTT v3.1.1 spec clarifies a number of ambiguities with regard
+// to the validity of Topic strings.
+// - A Topic must be between 1 and 65535 bytes.
+// - A Topic is case sensitive.
+// - A Topic may contain whitespace.
+// - A Topic containing a leading forward slash is different than a Topic without.
+// - A Topic may be "/" (two levels, both empty string).
+// - A Topic must be UTF-8 encoded.
+// - A Topic may contain any number of levels.
+// - A Topic may contain an empty level (two forward slashes in a row).
+// - A TopicName may not contain a wildcard.
+// - A TopicFilter may only have a # (multi-level) wildcard as the last level.
+// - A TopicFilter may contain any number of + (single-level) wildcards.
+// - A TopicFilter with a # will match the absense of a level
+//     Example:  a subscription to "foo/#" will match messages published to "foo".
+
+func validateSubscribeMap(subs map[string]byte) ([]string, []byte, error) {
+	var topics []string
+	var qoss []byte
+	for topic, qos := range subs {
+		if err := validateTopicAndQos(topic, qos); err != nil {
+			return nil, nil, err
+		}
+		topics = append(topics, topic)
+		qoss = append(qoss, qos)
+	}
+
+	return topics, qoss, nil
+}
+
+func validateTopicAndQos(topic string, qos byte) error {
+	if len(topic) == 0 {
+		return ErrInvalidTopicEmptyString
+	}
+
+	levels := strings.Split(topic, "/")
+	for i, level := range levels {
+		if level == "#" && i != len(levels)-1 {
+			return ErrInvalidTopicMultilevel
+		}
+	}
+
+	if qos < 0 || qos > 2 {
+		return ErrInvalidQos
+	}
+	return nil
+}