Add mosquitto_string_to_command.

lib/linker.version

@@ -94,7 +94,8 @@ MOSQ_1.5 {
 
 MOSQ_1.6 {
 	global:
-		mosquitto_subscribe_multiple;
 		mosquitto_property_free_all;
 		mosquitto_property_command_check;
+		mosquitto_string_to_command;
+		mosquitto_subscribe_multiple;
 } MOSQ_1.5;

lib/mosquitto.c

@@ -493,6 +493,40 @@ const char *mosquitto_reason_string(int reason_code)
 	}
 }
 
+
+int mosquitto_string_to_command(const char *str, int *cmd)
+{
+	if(!strcasecmp(str, "connect")){
+		*cmd = CMD_CONNECT;
+	}else if(!strcasecmp(str, "connack")){
+		*cmd = CMD_CONNACK;
+	}else if(!strcasecmp(str, "publish")){
+		*cmd = CMD_PUBLISH;
+	}else if(!strcasecmp(str, "puback")){
+		*cmd = CMD_PUBACK;
+	}else if(!strcasecmp(str, "pubrec")){
+		*cmd = CMD_PUBREC;
+	}else if(!strcasecmp(str, "pubrel")){
+		*cmd = CMD_PUBREL;
+	}else if(!strcasecmp(str, "pubcomp")){
+		*cmd = CMD_PUBCOMP;
+	}else if(!strcasecmp(str, "subscribe")){
+		*cmd = CMD_SUBSCRIBE;
+	}else if(!strcasecmp(str, "unsubscribe")){
+		*cmd = CMD_UNSUBSCRIBE;
+	}else if(!strcasecmp(str, "disconnect")){
+		*cmd = CMD_DISCONNECT;
+	}else if(!strcasecmp(str, "auth")){
+		*cmd = CMD_AUTH;
+	}else if(!strcasecmp(str, "will")){
+		*cmd = CMD_WILL;
+	}else{
+		return MOSQ_ERR_INVAL;
+	}
+	return MOSQ_ERR_SUCCESS;
+}
+
+
 int mosquitto_sub_topic_tokenise(const char *subtopic, char ***topics, int *count)
 {
 	int len;

lib/mosquitto.h

@@ -1568,6 +1568,25 @@ libmosq_EXPORT const char *mosquitto_strerror(int mosq_errno);
  */
 libmosq_EXPORT const char *mosquitto_connack_string(int connack_code);
 
+/* Function: mosquitto_string_to_command
+ *
+ * Take a string input representing an MQTT command and convert it to the
+ * libmosquitto integer representation.
+ *
+ * Parameters:
+ *   str - the string to parse.
+ *   cmd - pointer to an int, for the result.
+ *
+ * Returns:
+ *	MOSQ_ERR_SUCCESS - on success
+ *	MOSQ_ERR_INVAL - on an invalid input.
+ *
+ * Example:
+ *  mosquitto_string_to_command("CONNECT", &cmd);
+ *  // cmd == CMD_CONNECT
+ */
+libmosq_EXPORT int mosquitto_string_to_command(const char *str, int *cmd);
+
 /*
  * Function: mosquitto_sub_topic_tokenise
  *