File content as of revision 0:8b40576553d2:

/* 
 * In this example the HTTP request (text) received from a browser is echoed (sent back) to the browser.
 * Ethernet connection is via an ENC28J60 board driven by UIPEthernet
 */

#include "mbed.h"
#include <UIPEthernet.h>
#include <UIPServer.h>
#include <UIPClient.h>

// UIPEthernet is the name of a global instance of UIPEthernetClass.
// Do not change the name! It is used within the UIPEthernet library.
// Adapt the SPI pin names to your mbed platform/board if not present yet.
#if defined(TARGET_LPC1768)
UIPEthernetClass UIPEthernet(p11, p12, p13, p8);        // mosi, miso, sck, cs
#elif defined(TARGET_LPC1114)
UIPEthernetClass UIPEthernet(dp2, dp1, dp6, dp25);      // mosi, miso, sck, cs
#elif defined(TARGET_LPC11U68)
UIPEthernetClass UIPEthernet(P0_9, P0_8, P1_29, P0_2);  // mosi, miso, sck, cs
#elif defined (TARGET_NUCLEO_F103RB)
UIPEthernetClass UIPEthernet(PB_5, PB_4, PB_3, PB_6);   // mosi, miso, sck, cs
#endif

// MAC number must be unique within the connected network. Modify as appropriate.
const uint8_t    MY_MAC[6] = {0x00,0x01,0x02,0x03,0x04,0x05};
// IP address must be unique and compatible with your network. Change as appropriate.
const IPAddress  MY_IP(192,168,1,181);
const uint16_t   MY_PORT = 80;      // for HTTP connection
EthernetServer   myServer = EthernetServer(MY_PORT);
Serial           serial(USBTX, USBRX);

int main()
{
    Ethernet.begin(MY_MAC,MY_IP);
    myServer.begin();
    while(1) {
        EthernetClient client = myServer.available();
        if (client) {
            size_t size = client.available();
            if(size > 0) {
                char* buf = (char*)malloc(size);
                size = client.read((uint8_t*)buf, size);
                if(buf[0] == 'G' && buf[1] == 'E' && buf[2] == 'T') {
                    serial.printf("GET request received:\n\r");
                    serial.printf(buf);
                    char echoHeader[256] = {};
                    sprintf(echoHeader,"HTTP/1.1 200 OK\r\nContent-Length: %d\r\nContent-Type: text\r\nConnection: About to close\r\n\r\n", size);
                    client.write((uint8_t*)echoHeader,strlen(echoHeader));
                    client.write((uint8_t*)buf, size);
                    serial.printf("Echo done.\r\n");
                }
                free(buf);
            }
        }
    }
}