From 64b1de08be6e1e78d8858c43dddfbed08d0a3097 Mon Sep 17 00:00:00 2001
From: Bruno Crivelari Sanches <bcsanches@gmail.com>
Date: Mon, 5 Sep 2022 14:23:54 -0300
Subject: [PATCH] Detects when ethernet cable is connected and is disconnected,
 also correctly handles EthernetServer tead down on such situations

---
 EthernetInterface.cpp | 74 ++++++++++++++++++++++++++++++++++---------
 EthernetInterface.h   |  5 +--
 2 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/EthernetInterface.cpp b/EthernetInterface.cpp
index 9d04423..ddd762c 100644
--- a/EthernetInterface.cpp
+++ b/EthernetInterface.cpp
@@ -41,6 +41,7 @@ void EthernetInterface::setup()
      if (Ethernet.hardwareStatus() == EthernetNoHardware) {
       DIAG(F("Ethernet shield not found"));
 
+      delete singleton;
       singleton=NULL;
 
       return;
@@ -71,13 +72,24 @@ EthernetInterface::EthernetInterface()
     #endif       
 }
 
+/**
+ * @brief Cleanup any resources
+ * 
+ * @return none
+ */
+EthernetInterface::~EthernetInterface()
+{
+    delete server;
+    delete outboundRing;
+}
+
 /**
  * @brief Main loop for the EthernetInterface
  * 
  */
 void EthernetInterface::loop()
 {    
-    if(!singleton || ((!singleton->connected) && (!singleton->checkLink())))
+    if(!singleton || (!singleton->checkLink()))
         return;
     
     switch (Ethernet.maintain())
@@ -103,26 +115,58 @@ void EthernetInterface::loop()
 
 }
 
+/**
+ * @brief Checks ethernet link cable status and detects when it connects / disconnects
+ * 
+ * @return true when cable is connected, false otherwise
+ */
 bool EthernetInterface::checkLink()
 {    
-    if (Ethernet.linkStatus() != LinkON)
-        return false;
-
-    DIAG(F("Ethernet cable connected"));
+    if (Ethernet.linkStatus() == LinkON)
+    {
+        //if we are not connected yet, setup a new server
+        if(!connected)
+        {
+            DIAG(F("Ethernet cable connected"));
     
-    connected=true;
-    
-    IPAddress ip = Ethernet.localIP(); // reassign the obtained ip address
+            connected=true;
+            
+            IPAddress ip = Ethernet.localIP(); // reassign the obtained ip address
 
-    server = new EthernetServer(IP_PORT); // Ethernet Server listening on default port IP_PORT
-    server->begin();
-  
-    LCD(4,F("IP: %d.%d.%d.%d"), ip[0], ip[1], ip[2], ip[3]);
-    LCD(5,F("Port:%d"), IP_PORT);
+            server = new EthernetServer(IP_PORT); // Ethernet Server listening on default port IP_PORT
+            server->begin();
+        
+            LCD(4,F("IP: %d.%d.%d.%d"), ip[0], ip[1], ip[2], ip[3]);
+            LCD(5,F("Port:%d"), IP_PORT);
 
-    outboundRing=new RingStream(OUTBOUND_RING_SIZE);   
+            //
+            //only create a outboundRing it none exists, this may happen if the cable gets disconnected and connected again
+            if(!outboundRing)
+                outboundRing=new RingStream(OUTBOUND_RING_SIZE);   
+        }
 
-    return true;
+        return true;
+    }        
+    else if(connected)
+    {
+        DIAG(F("Ethernet cable disconnected"));
+        connected=false;
+
+        //clean up any client
+        for (byte socket = 0; socket < MAX_SOCK_NUM; socket++)
+        {
+            if(clients[socket].connected())
+                clients[socket].stop();
+        }            
+
+        /* tear down server */
+        delete server;
+        server = nullptr;
+
+        LCD(4,F("IP: None"));
+    }
+
+    return false;
 }
 
  void EthernetInterface::loop2()
diff --git a/EthernetInterface.h b/EthernetInterface.h
index ff673c1..ce5bbd9 100644
--- a/EthernetInterface.h
+++ b/EthernetInterface.h
@@ -59,14 +59,15 @@ class EthernetInterface {
      static EthernetInterface * singleton;
      bool connected;
      EthernetInterface();
+     ~EthernetInterface();
      void loop2();
 
      bool checkLink();
 
-    EthernetServer * server;
+    EthernetServer * server = nullptr;
     EthernetClient clients[MAX_SOCK_NUM];                // accept up to MAX_SOCK_NUM client connections at the same time; This depends on the chipset used on the Shield
     uint8_t buffer[MAX_ETH_BUFFER+1];                    // buffer used by TCP for the recv
-    RingStream * outboundRing;
+    RingStream * outboundRing = nullptr;
   
 };