udp.c

此文档为采用FPGA实现的以太网MAC层

#include "ip.h"
#include "udp.h"
#include "serial.h"
#include "mac.h"
#include "mac_low.h"
#include "ntp.h"
#include "dhcp.h"

extern Uint16 data_buffer[100];
extern IP_SETTINGS ipsettings;

UDPHEADER udp_header;

void udp_process(UDPHEADER * packet, Uint16 datasize, Uint16 sourceip_h, Uint16 sourceip_l)
{
    Uint16 datalen, x, y, * buf, * buf2;
    Uint8 * charptr;
    UDPHEADER   * packet2;
    NTPHEADER   * ntp_packet;
    DHCP_HEADER * dhcp_packet;
    Uint32        word;

    //Print src port

    buf2 = (Uint16 *)(EMAC_TX_PTR + UDP_DATA_OFFSET);
    word = (Uint32) packet;
    word += UDP_SIZE;

    if (packet->destport == 0x400)
    {
        datalen = udp_getlen(packet->length);

        //Read back data
        //mac_read(datalen,(Uint16 *)data_buffer);
        packet2 = (UDPHEADER *)(EMAC_TX_PTR + UDP_OFFSET);
        packet2->destport = packet2->sourceport = 0x400;

        //Copy data from buf (RX) to buf2 (TX)

        buf = (Uint16 *) word;

        for (x = 0; x < datalen; x++)
            buf2[x] = buf[x];

        x = udp_packet(packet2, sourceip_h, sourceip_l, buf2, datalen);
        ip_send(sourceip_h, sourceip_l, x, PROTOCOL_UDP);

    }
    else if (packet->destport == 123)
    {
        dbg(0xffff);
        ntp_packet = (NTPHEADER *) word;
        dbg_string((Uint16 *) & (ntp_packet->tx_timestamp_h), 2);
        //dbg32(ntp_packet->tx_timestamp_h);

    }

    else if (packet->destport == 0x44)
    {
        dbg(0xffff);

        dhcp_packet = (DHCP_HEADER *) word;

        dhcp_parse(dhcp_packet,sourceip_h,sourceip_l);


    }
    else
    {
        //dbg(packet->destport);
        //dbg(packet->sourceport);
    }

}

Uint16 udp_getlen(Uint16 len)
{
    return((len - 8) / 2);
}


//Expect source and destport to be filled out
//Returns length of packet in words
Uint16 udp_packet(UDPHEADER * packet, Uint16 dest_ip_h, Uint16 dest_ip_l, Uint16 * databuf, Uint16 data_len)
{
    Uint16 * intptr;

    //Fill in length field
    packet->length = 8 + (data_len * 2);

    //Dummy checkum
    packet->checksum = 0x0000;

    //Append pseudo-header
    //Set pointer to end of data buffer - data starts at packet+8
    //intptr = ((Uint16 *) packet)+((packet->length)/2);
    intptr = (Uint16 *)(databuf + data_len);

    * (intptr++) = ipsettings.ip_address_h;
    * (intptr++) = ipsettings.ip_address_l;

    //High int of dest ip
    * (intptr++) = dest_ip_h;
    * (intptr++) = dest_ip_l;

    //append length
    * (intptr++) = packet->length;
    //append protocol
    * (intptr++) = PROTOCOL_UDP;

    //pseudo header generated, calculate checksum
    //packet->checksum = ip_chksum((Uint16 *) packet,((packet->length)/2)+6);
    packet->checksum = ip_chksum2((Uint16 *) packet, UDP_SIZE / 2, databuf, data_len + 6);

    return(packet->length) / 2;

}