Fix for issue 62, adding DHCP support. New begin() method added to EthernetClass which takes just a MAC address and gets the rest of its configuration information via DHCP. Examples updated to use the IPAddress class and some have been changed to get their config via DHCP.

libraries/Ethernet/examples/PachubeClient/PachubeClient.pde

@@ -23,20 +23,13 @@
 #include <Ethernet.h>
 
 // assign a MAC address for the ethernet controller.
+// Newer Ethernet shields have a MAC address printed on a sticker on the shield
 // fill in your address here:
 byte mac[] = { 
   0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
-// assign an IP address for the controller:
-byte ip[] = { 
-  192,169,1,20 };
-byte gateway[] = {
-  192,168,1,1};	
-byte subnet[] = { 
-  255, 255, 255, 0 };
 
 //  The address of the server you want to connect to (pachube.com):
-byte server[] = { 
-  209,40,205,190 }; 
+IPAddress server(209,40,205,190); 
 
 // initialize the library instance:
 Client client(server, 80);
@@ -46,9 +39,15 @@ boolean lastConnected = false;      // state of the connection last time through
 const int postingInterval = 10000;  //delay between updates to Pachube.com
 
 void setup() {
-  // start the ethernet connection and serial port:
-  Ethernet.begin(mac, ip);
+  // start serial port:
   Serial.begin(9600);
+  // start the Ethernet connection:
+  if (Ethernet.begin(mac) == 0) {
+    Serial.println("Failed to configure Ethernet using DHCP");
+    // no point in carrying on, so do nothing forevermore:
+    for(;;)
+      ;
+  }
   // give the ethernet module time to boot up:
   delay(1000);
 }