dhcp.c

此文档为采用FPGA实现的以太网MAC层

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

extern IP_SETTINGS ipsettings;
extern IP_TABLE iptable;

volatile Uint16 dhcp_timer = 20;

void dhcp_parse(DHCP_HEADER *dhcp_packet,Uint16 srcip_h,Uint16 srcip_l)
{
    Uint8 x,*charptr;
    Uint32 word;
    Uint16 tmpint;
    DHCP_OPT    * dhcp_option;

    //Check if packet is an Offer reply
    //dhcp_packet = (DHCP_HEADER *) word;
    //DHCP packet points to start of BOOTp packet
    //Check if boot reply
    if (dhcp_packet->opcode != 2)
        return;

    //Check MAC address
    for (x = 0; x < 6; x++)
    {
       //dbg(0xeeee);
       //dbg_char(dhcp_packet->clienthw_addr[x]);
        if (dhcp_packet->clienthw_addr[x] != ipsettings.mac_address[x])
            return;
    }

    word = (Uint32) dhcp_packet;
    //Seek to data
    word += DHCP_SIZE;

    //Set x to 0 to indicate no need to replace DNS server
    x=0;

    //Keep seeking until 0xff is hit in the opcode field
    while (1)
    {
        dhcp_option = (DHCP_OPT *) word;
        charptr = (Uint8 *)(word + 2);

        switch(dhcp_option->opcode)
        {
          case 0xff:
            return;
            break;

          case 0x35:
               //DHCP message type field
               if (charptr[0] == 2)
               {
                  //DHCP offer found, grap ip's
                  dhcp_sendack(dhcp_packet->yourip_h, dhcp_packet->yourip_l,srcip_h,srcip_l);
                  return;
               }
               if (charptr[0] == 6)
               {
                //NACK received, request again
                dhcp_getip();
               }
               if (charptr[0] == 5)
               {
                //ACK received
                //Search for DNS server
                //Set x to 1 to indicate the DNS server needs to be written
                x=1;
               }

               break;

          case 0x6:
               //Break if we don't need to write DNS server
               if (!x) break;

               //DNS server field
               //First two bytes are high field
               tmpint = (Uint16)((*(charptr++)) << 8);
               tmpint |= (Uint16)((*(charptr++)) & 0xff);

               iptable.dns_server.ip_h = tmpint;
               dbg(tmpint);

               tmpint = (Uint16)((*(charptr++)) << 8);
               tmpint |= (Uint16)((*(charptr++)) & 0xff);

               iptable.dns_server.ip_l = tmpint;
               dbg(tmpint);
               break;



        }


        word += DHCPOPT_SIZE + dhcp_option->len;
    }

}

void dhcp_getip(void)
{
    DHCP_HEADER * packet;
    DHCP_OPT    * dhcpopt;
    UDPHEADER   * udppacket;
    Uint16      * buf, x;
    Uint8       * charptr;

    //Reset ip
    ipsettings.ip_address_h = ipsettings.ip_address_l = 0;

    packet = (DHCP_HEADER *)(EMAC_TX_PTR + DHCP_OFFSET);
    udppacket = (UDPHEADER *)(EMAC_TX_PTR + UDP_OFFSET);
    buf = (Uint16 *) packet;

    //Zero packet

    for (x = 0; x < (DHCP_SIZE / 2); x++)
    {
        buf[x] = 0;
    }

    packet->opcode = 1;
    packet->hw_type = 1;
    packet->hw_addrlen = 6;
    packet->xid_h = 0xfaaf;
    packet->xid_l = 0xeffe;

    for (x = 0; x < 6; x++)
    {
        packet->clienthw_addr[x] = ipsettings.mac_address[x];
    }

    packet->magic_cookie_h = 0x6382;
    packet->magic_cookie_l = 0x5363;

    //Fill out Message type header
    dhcpopt = (DHCP_OPT *)(EMAC_TX_PTR + DHCPOPT_ROOT);

    dhcpopt->opcode = 0x35;
    dhcpopt->len = 1;

    charptr = (Uint8 *) dhcpopt;
    charptr += DHCPOPT_SIZE;

    * (charptr++) = 1;

    //Fill out client identifier header

    * (charptr++) = 0x3d;
    * (charptr++) = 0x07;
    * (charptr++) = 0x1;

    //Copy in MAC address
    for (x = 0; x < 6; x++)
    {
        * (charptr++) = ipsettings.mac_address[x];
    }

    //Fill out IP Field

    * (charptr++) = 0x32;
    * (charptr++) = 0x4;

    * (charptr++) = ipsettings.ip_address_h >> 8;
    * (charptr++) = ipsettings.ip_address_h & 0xff;
    * (charptr++) = ipsettings.ip_address_l >> 8;
    * (charptr++) = ipsettings.ip_address_l & 0xff;

//    * (charptr++) = 0xc0;
//    * (charptr++) = 0xa8;
//    * (charptr++) = 0x01;
//    * (charptr++) = 0x6e;

      //End of packet

    * (charptr++) = 0xff;

    //Fill out udp packet information
    udppacket->sourceport = 0x44;
    udppacket->destport = 0x43;

    //dbg((DHCP_SIZE+20)/2);
    x = udp_packet(udppacket, 0xffff, 0xffff, (Uint16 *) packet, (DHCP_SIZE + 20) / 2);
    //dbg(x);
    //ip_send(0xc0a8,0x0101,x,PROTOCOL_UDP);
    ip_send(0xffff, 0xffff, x, PROTOCOL_UDP);

}

void dhcp_sendack(Uint16 ip_h, Uint16 ip_l, Uint16 serverip_h, Uint16 serverip_l)
{
    DHCP_HEADER * packet;
    DHCP_OPT    * dhcpopt;
    UDPHEADER   * udppacket;
    Uint16      * buf, x;
    Uint8       * charptr;

    dbg(ip_h);
    dbg(ip_l);

    //Set ip_address
    ipsettings.ip_address_h = ip_h;
    ipsettings.ip_address_l = ip_l;

    packet = (DHCP_HEADER *)(EMAC_TX_PTR + DHCP_OFFSET);
    udppacket = (UDPHEADER *)(EMAC_TX_PTR + UDP_OFFSET);
    buf = (Uint16 *) packet;

    //Fill out Message type header
    dhcpopt = (DHCP_OPT *)(EMAC_TX_PTR + DHCPOPT_ROOT);

    dhcpopt->opcode = 0x35;
    dhcpopt->len = 1;

    for (x = 0; x < 6; x++)
    {
        packet->clienthw_addr[x] = ipsettings.mac_address[x];
    }


    charptr = (Uint8 *) dhcpopt;
    charptr += DHCPOPT_SIZE;

    * (charptr++) = 3;

    //Fill out client identifier header

    * (charptr++) = 0x3d;
    * (charptr++) = 0x07;
    //HW type to ethernet
    * (charptr++) = 0x1;

    //Fill out MAC adress
    for (x = 0; x < 6; x++)
    {
        * (charptr++) = ipsettings.mac_address[x];
    }

    //Requested IP field

    * (charptr++) = 0x32;
    * (charptr++) = 0x4;

    //Store obtained IP
    * (charptr++) = (Uint8)(ip_h >> 8);
    * (charptr++) = (Uint8)(ip_h & 0xff);
    * (charptr++) = (Uint8)(ip_l >> 8);
    * (charptr++) = (Uint8)(ip_l & 0xff);

    * (charptr++) = 0xff;

    //Fill out udp packet information
    udppacket->sourceport = 0x44;
    udppacket->destport = 0x43;

    //dbg((DHCP_SIZE+20)/2);
    x = udp_packet(udppacket, serverip_h, serverip_l, (Uint16 *) packet, (DHCP_SIZE + 20) / 2);
    //dbg(x);
    ip_send(serverip_h, serverip_l, x, PROTOCOL_UDP);

}