Adding ethernet library.

hardware/libraries/Ethernet/examples/echo_server/echo_server.pde

@@ -0,0 +1,53 @@
+/*
+ * Echo Server
+ *
+ * Echoes back the headers of the web request.  Good for
+ * learning how the HTTP protocol works.
+ */
+
+#include <Ethernet.h>
+
+byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
+byte ip[] = { 10, 0, 0, 177 };
+
+Server server(80);
+
+void setup()
+{
+  Client client(255);
+  Ethernet.begin(mac, ip);
+  Serial.begin(9600);
+  server.begin();
+}
+
+void loop()
+{
+  char buf[512];
+  int i = 0;
+  Client client = server.available();
+  if (client) {
+    boolean previous_is_newline = false;
+    while (client.connected()) {
+      if (client.available()) {
+        char c = client.read();
+        if (c == '\n' && previous_is_newline) {
+          buf[i] = 0;
+          client.println("HTTP/1.1 200 OK");
+          client.println("Content-Type: text/html");
+          client.println();
+          client.println("<pre>");
+          client.println(buf);
+          client.println("</pre>");
+          break;
+        }
+        if (i < 511)
+          buf[i++] = c;
+        if (c == '\n')
+          previous_is_newline = true;
+        else if (c != '\r')
+          previous_is_newline = false;
+      }
+    }
+    client.stop();
+  }
+}