Final changes for the Client part of issue 416, which actually include the corrent return values. This should have been in the previous commit, but I'm still getting my head round git.

libraries/Ethernet/Client.cpp

@@ -77,7 +77,7 @@ int Client::available() {
 
 int Client::read() {
   uint8_t b;
-  if ( recv(_sock, &b, 1) )
+  if ( recv(_sock, &b, 1) > 0 )
   {
     // recv worked
     return b;

libraries/Ethernet/utility/socket.cpp

@@ -148,7 +148,22 @@ uint16_t recv(SOCKET s, uint8_t *buf, uint16_t len)
 {
   // Check how much data is available
   uint16_t ret = W5100.getRXReceivedSize(s);
-  if (ret > len)
+  if ( ret == 0 )
+  {
+    // No data available.
+    uint8_t status = W5100.readSnSR(s);
+    if ( s == SnSR::LISTEN || s == SnSR::CLOSED || s == SnSR::CLOSE_WAIT )
+    {
+      // The remote end has closed its side of the connection, so this is the eof state
+      ret = 0;
+    }
+    else
+    {
+      // The connection is still up, but there's no data waiting to be read
+      ret = -1;
+    }
+  }
+  else if (ret > len)
   {
     ret = len;
   }