From 5a1b0a0c28166ab99ca6fb4aee8391475efbb1c3 Mon Sep 17 00:00:00 2001
From: Paul Melnikov <positron96@gmail.com>
Date: Thu, 3 Jun 2021 17:16:35 +0700
Subject: [PATCH] Attempt to add TCP keepalive functionality.

---
 src/AsyncTCP.cpp | 12 ++++++++++++
 src/AsyncTCP.h   |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/src/AsyncTCP.cpp b/src/AsyncTCP.cpp
index 89ff6ee3..6003bd2d 100644
--- a/src/AsyncTCP.cpp
+++ b/src/AsyncTCP.cpp
@@ -1057,6 +1057,18 @@ bool AsyncClient::getNoDelay(){
     return tcp_nagle_disabled(_pcb);
 }
 
+void AsyncClient::setKeepAlive(uint32_t ms, uint8_t cnt){
+    if(ms!=0) {
+        _pcb->so_options |= SOF_KEEPALIVE; //Turn on TCP Keepalive for the given pcb
+        // Set the time between keepalive messages in milli-seconds
+        _pcb->keep_idle = ms;
+        _pcb->keep_intvl = ms;
+        _pcb->keep_cnt = cnt; //The number of unanswered probes required to force closure of the socket
+    } else {
+        _pcb->so_options &= ~SOF_KEEPALIVE; //Turn off TCP Keepalive for the given pcb
+    }
+}
+
 uint16_t AsyncClient::getMss(){
     if(!_pcb) {
         return 0;
diff --git a/src/AsyncTCP.h b/src/AsyncTCP.h
index ac87deda..75838515 100644
--- a/src/AsyncTCP.h
+++ b/src/AsyncTCP.h
@@ -99,6 +99,8 @@ class AsyncClient {
     void setNoDelay(bool nodelay);
     bool getNoDelay();
 
+    void setKeepAlive(uint32_t ms, uint8_t cnt);
+
     uint32_t getRemoteAddress();
     uint16_t getRemotePort();
     uint32_t getLocalAddress();