From 280e61e1fc4d602b9562e23e9ed1560cb9ccd97e Mon Sep 17 00:00:00 2001
From: Harald Barth <haba@kth.se>
Date: Mon, 7 Nov 2022 11:53:56 +0100
Subject: [PATCH] Make EthernetInterface code more robust

---
 EthernetInterface.cpp | 8 +++++++-
 EthernetInterface.h   | 2 +-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/EthernetInterface.cpp b/EthernetInterface.cpp
index 2668ece..8dd4d31 100644
--- a/EthernetInterface.cpp
+++ b/EthernetInterface.cpp
@@ -163,6 +163,10 @@ bool EthernetInterface::checkLink() {
 }
 
 void EthernetInterface::loop2() {
+    if (!outboundRing) { // no idea to call loop2() if we can't handle outgoing data in it
+      if (Diag::ETHERNET) DIAG(F("No outboundRing"));
+      return;
+    }
     // get client from the server
     EthernetClient client = server->accept();
 
@@ -217,7 +221,9 @@ void EthernetInterface::loop2() {
     
     // handle at most 1 outbound transmission 
     int socketOut=outboundRing->read();
-    if (socketOut>=0) {
+    if (socketOut >= MAX_SOCK_NUM) {
+      DIAG(F("Ethernet outboundRing socket=%d error"), socketOut);
+    } else if (socketOut >= 0) {
       int count=outboundRing->count();
       if (Diag::ETHERNET) DIAG(F("Ethernet reply socket=%d, count=:%d"), socketOut,count);
       for(;count>0;count--)  clients[socketOut].write(outboundRing->read());
diff --git a/EthernetInterface.h b/EthernetInterface.h
index e9b6c60..8078c3f 100644
--- a/EthernetInterface.h
+++ b/EthernetInterface.h
@@ -62,7 +62,7 @@ class EthernetInterface {
     ~EthernetInterface();
     void loop2();
     bool checkLink();
-    EthernetServer * server;
+    EthernetServer * server = NULL;
     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 = NULL;