aqhome/mqtt: added messages regarding subscription.

aqhome/mqtt/msg_mqtt.c

@@ -168,6 +168,40 @@ void _flagsToDb(uint8_t flags, GWEN_DB_NODE *dbDest, const char *varNameFlags, c
 
 
 
+/* helper functions */
+
+
+void AQH_MqttMsg_AppendStringWithLen(GWEN_BUFFER *buf, const char *s)
+{
+  unsigned int len;
+
+  len=strlen(s);
+  GWEN_Buffer_AppendByte(buf, (len>>8) & 0xff);
+  GWEN_Buffer_AppendByte(buf, len & 0xff);
+  if (s && *s)
+    GWEN_Buffer_AppendString(buf, s);
+}
+
+
+
+int AQH_MqttMsg_DumpString(const uint8_t *ptr, uint32_t len, GWEN_BUFFER *buf)
+{
+  if (len>1) {
+    int slen;
+
+    slen=(ptr[0]<<8)+ptr[1];
+    if (slen) {
+      if (slen>(len-2)) {
+        DBG_ERROR(AQH_LOGDOMAIN, "Invalid string length (%lu, remaining %lu)",
+                  (unsigned long int) slen, (unsigned long int) len);
+        return GWEN_ERROR_BAD_DATA;
+      }
+      GWEN_Buffer_AppendBytes(buf, (const char*) ptr+2, slen);
+    }
+    return slen+2;
+  }
+  return GWEN_ERROR_BAD_DATA;
+}