Server on Arduino Ethernet fails

Using Arduino Networking, Protocols, and Devices
27

It's the r17 revision from 2008.

Try something newer. This works for me. It has a form page. Change the network settings if necessary. Compile, upload, and open the serial monitor.

#include <SPI.h>
#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip( 192,168,0,2 );
IPAddress gateway( 192,168,0,1 );
IPAddress subnet( 255,255,255,0 );

EthernetServer server(80);

void setup()
{
  Serial.begin(9600);
  pinMode(4,OUTPUT);
  digitalWrite(4,HIGH);
  Ethernet.begin(mac, ip, gateway, gateway, subnet);
  delay(2000);
  server.begin();
  Serial.println("Ready");
}

void loop()
{
  EthernetClient client = server.available();
  if(client) {
    boolean currentLineIsBlank = true;
    boolean currentLineIsGet = true;
    int tCount = 0;
    char tBuf[64];
    int r,t;
    char *pch;
    
    Serial.print("Client request: ");
    
    while (client.connected()) {
      while(client.available()) {
        char c = client.read();

        if(currentLineIsGet && tCount < 63)
        {
          tBuf[tCount] = c;
          tCount++;
          tBuf[tCount] = 0;          
        }

        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response
          while(client.available()) client.read();
          Serial.println(tBuf);
          pch = strtok(tBuf,"?");

          while(pch != NULL)
          {
            if(strncmp(pch,"t=",2) == 0)
            {
              t = atoi(pch+2);
              Serial.print("t=");
              Serial.println(t,DEC);             
            }

            if(strncmp(pch,"r=",2) == 0)
            {
              r = atoi(pch+2);
              Serial.print("r=");              
              Serial.println(r,DEC);
            }


            pch = strtok(NULL,"& ");
          }
          Serial.println("Sending response");
          client.write("HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<html><body><H1>TEST</H1>");

          client.write("<form method=GET>T: <input type=text name=t>
");
          client.write("R: <input type=text name=r>
<input type=submit></form>");
          
          client.write("</body></html>\r\n\r\n");
          client.stop();
        }
        else if (c == '\n') {
          currentLineIsBlank = true;
          currentLineIsGet = false;
        } 
        else if (c != '\r') {
          currentLineIsBlank = false;
        }
      }
    }
    Serial.println("done");
  }
}

You may need to remove the serial output if you don't have that feature.

edit: I don't see how you would troubleshoot this without a usb/serial port. If you don't have that adapter, I recommend you get one.