Add DHCP hostname option

examples/DhcpHostname/DhcpHostname.ino

@@ -0,0 +1,46 @@
+/*
+  DHCP-based hostname printer
+
+  Circuit:
+   Ethernet shield attached to pins 10, 11, 12, 13
+
+  created 10 Dec 2016
+  by mykh
+*/
+
+#include <Ethernet.h>
+
+// MAC address
+byte mac[] = {
+  0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x02
+};
+// Hostname
+const char* hostname = "myarduino";
+
+// Initialize the Ethernet client library
+EthernetClient client;
+
+void setup() {
+  // Open serial communications and wait for port to open:
+  Serial.begin(9600);
+  // this check is only needed on the Leonardo:
+  while (!Serial) {
+    ;
+  }
+
+  // start the Ethernet connection:
+  Serial.println("Setup...");
+  while (Ethernet.begin(mac, hostname) == 0) {
+    Serial.println("Failed to configure Ethernet using DHCP");
+    delay(10000);
+    Serial.println("Reconnecting...");
+  }
+
+  // print your hostname:
+  Serial.print("My Hostname: ");
+  Serial.println(Ethernet.hostname());
+}
+
+void loop() {
+  Ethernet.maintain();
+}

src/Dhcp.cpp

@@ -7,6 +7,11 @@
 #include "utility/w5100.h"
 
 int DhcpClass::beginWithDHCP(uint8_t *mac, unsigned long timeout, unsigned long responseTimeout)
+{
+	return beginWithDHCP(mac, NULL, timeout, responseTimeout);
+}
+
+int DhcpClass::beginWithDHCP(uint8_t *mac, const char *hostname, unsigned long timeout, unsigned long responseTimeout)
 {
 	_dhcpLeaseTime=0;
 	_dhcpT1=0;
@@ -18,6 +23,20 @@ int DhcpClass::beginWithDHCP(uint8_t *mac, unsigned long timeout, unsigned long
 	memset(_dhcpMacAddr, 0, 6);
 	reset_DHCP_lease();
 
+	if (NULL == hostname)
+	{
+		strcpy(_dhcpHostname, HOST_NAME);
+		int offset = strlen(HOST_NAME);
+		printByte((char*)&(_dhcpHostname[offset + 0]), mac[3]);
+		printByte((char*)&(_dhcpHostname[offset + 2]), mac[4]);
+		printByte((char*)&(_dhcpHostname[offset + 4]), mac[5]);
+		_dhcpHostname[offset + 6] = 0;
+	}
+	else
+	{
+		strlcpy(_dhcpHostname, hostname, MAX_HOST_NAME_LENGTH + 1);
+	}
+
 	memcpy((void*)_dhcpMacAddr, (void*)mac, 6);
 	_dhcp_state = STATE_DHCP_START;
 	return request_DHCP_lease();
@@ -188,12 +207,8 @@ void DhcpClass::send_DHCP_MESSAGE(uint8_t messageType, uint16_t secondsElapsed)
 
 	// OPT - host name
 	buffer[16] = hostName;
-	buffer[17] = strlen(HOST_NAME) + 6; // length of hostname + last 3 bytes of mac address
-	strcpy((char*)&(buffer[18]), HOST_NAME);
-
-	printByte((char*)&(buffer[24]), _dhcpMacAddr[3]);
-	printByte((char*)&(buffer[26]), _dhcpMacAddr[4]);
-	printByte((char*)&(buffer[28]), _dhcpMacAddr[5]);
+	buffer[17] = strlen(_dhcpHostname); // length of hostname
+	strcpy((char*)&(buffer[18]), _dhcpHostname);
 
 	//put data in W5100 transmit buffer
 	_dhcpUdpSocket.write(buffer, 30);
@@ -420,6 +435,11 @@ IPAddress DhcpClass::getDnsServerIp()
 	return IPAddress(_dhcpDnsServerIp);
 }
 
+const char* DhcpClass::getHostname() const
+{
+	return _dhcpHostname;
+}
+
 void DhcpClass::printByte(char * buf, uint8_t n )
 {
 	char *str = &buf[1];

src/Dhcp.h

@@ -42,7 +42,8 @@
 #define MAGIC_COOKIE		0x63825363
 #define MAX_DHCP_OPT		16
 
-#define HOST_NAME "WIZnet"
+#define HOST_NAME "WIZnet" //default host name
+#define MAX_HOST_NAME_LENGTH	12
 #define DEFAULT_LEASE	(900) //default lease time in seconds
 
 #define DHCP_CHECK_NONE         (0)

src/Ethernet.cpp

@@ -27,6 +27,11 @@ IPAddress EthernetClass::_dnsServerAddress;
 DhcpClass* EthernetClass::_dhcp = NULL;
 
 int EthernetClass::begin(uint8_t *mac, unsigned long timeout, unsigned long responseTimeout)
+{
+	begin(mac, NULL, timeout, responseTimeout);
+}
+
+int EthernetClass::begin(uint8_t *mac, const char* hostname, unsigned long timeout, unsigned long responseTimeout)
 {
 	static DhcpClass s_dhcp;
 	_dhcp = &s_dhcp;
@@ -39,7 +44,7 @@ int EthernetClass::begin(uint8_t *mac, unsigned long timeout, unsigned long resp
 	SPI.endTransaction();
 
 	// Now try to get our config info from a DHCP server
-	int ret = _dhcp->beginWithDHCP(mac, timeout, responseTimeout);
+	int ret = _dhcp->beginWithDHCP(mac, hostname, timeout, responseTimeout);
 	if (ret == 1) {
 		// We've successfully found a DHCP server and got our configuration
 		// info, so set things accordingly
@@ -230,7 +235,10 @@ void EthernetClass::setRetransmissionCount(uint8_t num)
 	SPI.endTransaction();
 }
 
-
+const char* EthernetClass::hostname() const
+{
+	return _dhcp ? _dhcp->getHostname() : "";
+}
 
 
 

src/Ethernet.h

@@ -50,6 +50,7 @@
 
 #include <Arduino.h>
 #include "Client.h"
+#include "Dhcp.h"
 #include "Server.h"
 #include "Udp.h"
 
@@ -80,6 +81,7 @@ class EthernetClass {
 	// gain the rest of the configuration through DHCP.
 	// Returns 0 if the DHCP configuration failed, and 1 if it succeeded
 	static int begin(uint8_t *mac, unsigned long timeout = 60000, unsigned long responseTimeout = 4000);
+	static int begin(uint8_t *mac, const char *hostname, unsigned long timeout = 60000, unsigned long responseTimeout = 4000);
 	static int maintain();
 	static EthernetLinkStatus linkStatus();
 	static EthernetHardwareStatus hardwareStatus();
@@ -96,6 +98,7 @@ class EthernetClass {
 	static IPAddress subnetMask();
 	static IPAddress gatewayIP();
 	static IPAddress dnsServerIP() { return _dnsServerAddress; }
+	const char* hostname() const;
 
 	void setMACAddress(const uint8_t *mac_address);
 	void setLocalIP(const IPAddress local_ip);
@@ -296,6 +299,7 @@ class DhcpClass {
 	unsigned long _lastCheckLeaseMillis;
 	uint8_t _dhcp_state;
 	EthernetUDP _dhcpUdpSocket;
+	char _dhcpHostname[MAX_HOST_NAME_LENGTH + 1];
 
 	int request_DHCP_lease();
 	void reset_DHCP_lease();
@@ -310,8 +314,10 @@ class DhcpClass {
 	IPAddress getGatewayIp();
 	IPAddress getDhcpServerIp();
 	IPAddress getDnsServerIp();
+	const char* getHostname() const;
 
 	int beginWithDHCP(uint8_t *, unsigned long timeout = 60000, unsigned long responseTimeout = 4000);
+	int beginWithDHCP(uint8_t *, const char *, unsigned long timeout = 60000, unsigned long responseTimeout = 4000);
 	int checkLease();
 };