add method to get tcp MSS

Author: me-no-dev

src/ESPAsyncTCP.cpp

@@ -536,6 +536,12 @@ bool AsyncClient::getNoDelay(){
   return tcp_nagle_disabled(_pcb);
 }
 
+uint16_t AsyncClient::getMss(){
+  if(_pcb)
+    return tcp_mss(_pcb);
+  return 0;
+}
+
 uint32_t AsyncClient::getRemoteAddress() {
   if(!_pcb)
     return 0;

src/ESPAsyncTCP.h

@@ -153,6 +153,7 @@ class AsyncClient {
     bool disconnected();
     bool freeable();//disconnected or disconnecting
 
+    uint16_t getMss();
     uint32_t getRxTimeout();
     void setRxTimeout(uint32_t timeout);//no RX data timeout for the connection in seconds
     uint32_t getAckTimeout();