zeroconf.c

Intrisyc 公司的PXA255-bootloader,源码易懂

////////////////////////////////////////////////////////////////////////////////
//
// Copyright(c) 2002 Intrinsyc Software Inc. All rights reserved.
//
// Module name:
//
//      zeroconf.c
//
// Description:
//
//      Handles Zeroconf IP address assignment (see http://www.zeroconf.org)
//      (draft-ietf-zeroconf-ipv4-linklocal-xx.txt)
//
// Author:
//
//      Dan Fandrich
//
// Created:
//
//      September 2002
//
////////////////////////////////////////////////////////////////////////////////

#include <string.h>
#include <debug.h>
#include <c_main.h>
#include <util.h>
#include <ip.h>
#include <arp.h>
#include <timer.h>
#include <zeroconf.h>

////////////////////////////////////////////////////////////////////////////////
// init_zeroconf
// PURPOSE: Handles the Zeroconf protocol to obtain the board's IP address
// PARAMS:  (IN) u32 *ciaddr - Client IP address returned.
//          (IN) u32 *siaddr - TFTP or other server address.
//          (IN) u32 *giaddr - gateway address.
//          (IN) u32 *smask  - IP netmask
//          (IN) int *ttl  - IP TTL
// RETURNS: 1 for success, 0 for failure. Some parameters are changed
//          on failure.
// NOTES:   The pointers must point to the actual structures used by the
//          network stack.
////////////////////////////////////////////////////////////////////////////////
int
init_zeroconf(u32 * ciaddr, u32 * siaddr, u32 * giaddr, u32 * smask, int *ttl)
{
    u32 ip;
    u16 mac[3];
    int retries = 0;

    *ciaddr = 0;                // We must start with a zero address
    *giaddr = 0;                // Zeroconf networking is unrouted
    *smask = 0;                 // Zeroconf networking is unrouted
    *ttl = ZEROCONF_TTL;

    // Delay a short random amount to space out Zeroconf requests from
    // many clients booting up at once.
    udelay(rand() % 100000);
    udelay(rand() % 100000);

    // Initial PRNG to a consistent value, unique to this device
    srand((status.macaddr[2] << 16) | status.macaddr[1]);

    // Do ARP Probes until we find a free one
    while (1)
    {
        do
        {
            if (++retries > ZEROCONF_RETRIES)
            {
                itc_printf("Couldn't obtain an address\r\n");
                ip = 0;
                break;
            }

            // Loop until we generate a valid address
            do
            {
                ip = ZEROCONF_NET | (rand() & 0xffff);
            } while (ip < ZEROCONF_IP_RANGE_MIN || ip > ZEROCONF_IP_RANGE_MAX);

            itc_printf(".");
            DEBUG_2("Trying IP %s\r\n", iptoa(ip));

        } while (arp(ip, mac));

        // Plug our IP address into the network stack
        *ciaddr = ip;

        DEBUG_2("Announcing our IP\r\n");
        // Do ARP Announcements & ensure that our address is still free
        if (ip && !arp(ip, mac))
        {
            // We have our address!
            break;
        }

        ip = 0;
        *ciaddr = ip;
    }

    // Reseed the random number generator with more entropy for other callers
    srand(get_time_timer() ^ ((status.macaddr[2] << 16) | status.macaddr[1]));

    return !!ip;
}