// Copyright (C) 2010 Georg Kaindl
// http://gkaindl.com
//
// This file is part of Arduino EthernetDHCP.
//
// EthernetDHCP is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of
// the License, or (at your option) any later version.
//
// EthernetDHCP is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with EthernetDHCP. If not, see
// <http://www.gnu.org/licenses/>.
//
// Illustrates how to use EthernetDHCP in synchronous (blocking)
// mode.
#include <Ethernet.h>
#include <EthernetDHCP.h>
byte mac = { 0x00, 0x1F, 0x16, 0x58, 0xEB, 0xA3 };
byte server = { 195, 88, 55, 16 }; // www.vg.no
Client client(server, 80);
const char* ip_to_str(const uint8_t*);
void setup()
{
Serial.begin(9600);
Serial.println(“Attempting to obtain a DHCP lease…”);
// Initiate a DHCP session. The argument is the MAC (hardware) address that
// you want your Ethernet shield to use. This call will block until a DHCP
// lease has been obtained. The request will be periodically resent until
// a lease is granted, but if there is no DHCP server on the network or if
// the server fails to respond, this call will block forever.
// Thus, you can alternatively use polling mode to check whether a DHCP
// lease has been obtained, so that you can react if the server does not
// respond (see the PollingDHCP example).
EthernetDHCP.begin(mac);
// Since we’re here, it means that we now have a DHCP lease, so we print
// out some information.
const byte* ipAddr = EthernetDHCP.ipAddress();
const byte* gatewayAddr = EthernetDHCP.gatewayIpAddress();
const byte* dnsAddr = EthernetDHCP.dnsIpAddress();
Serial.println(“A DHCP lease has been obtained.”);
Serial.print("My IP address is ");
Serial.println(ip_to_str(ipAddr));
Serial.print("Gateway IP address is ");
Serial.println(ip_to_str(gatewayAddr));
Serial.print("DNS IP address is ");
Serial.println(ip_to_str(dnsAddr));
Serial.begin(9600);
delay(1000);
Serial.println(“connecting…”);
if (client.connect()) {
Serial.println(“connected”);
client.println(“GET /search?q=arduino HTTP/1.0”);
client.println();
} else {
Serial.println(“connection failed”);
}
}
void loop()
{
if (client.available()) {
char c = client.read();
Serial.print(c);
}
if (!client.connected()) {
Serial.println();
Serial.println(“disconnecting.”);
client.stop();
for(;
;
}
// You should periodically call this method in your loop(): It will allow
// the DHCP library to maintain your DHCP lease, which means that it will
// periodically renew the lease and rebind if the lease cannot be renewed.
// Thus, unless you call this somewhere in your loop, your DHCP lease might
// expire, which you probably do not want 
EthernetDHCP.maintain();
}
// Just a utility function to nicely format an IP address.
const char* ip_to_str(const uint8_t* ipAddr)
{
static char buf[16];
sprintf(buf, “%d.%d.%d.%d\0”, ipAddr[0], ipAddr[1], ipAddr[2], ipAddr[3]);
return buf;
}