main.c

i386的bootloader源码grub

/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2000,2001,2002  Free Software Foundation, Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/* Based on "src/main.c" in etherboot-5.0.5.  */

/**************************************************************************
ETHERBOOT -  BOOTP/TFTP Bootstrap Program

Author: Martin Renters
  Date: Dec/93
  
Literature dealing with the network protocols:
       ARP - RFC826
       RARP - RFC903
       UDP - RFC768
       BOOTP - RFC951, RFC2132 (vendor extensions)
       DHCP - RFC2131, RFC2132 (options)
       TFTP - RFC1350, RFC2347 (options), RFC2348 (blocksize), RFC2349 (tsize)
       RPC - RFC1831, RFC1832 (XDR), RFC1833 (rpcbind/portmapper)
       NFS - RFC1094, RFC1813 (v3, useful for clarifications, not implemented)

**************************************************************************/

#define GRUB	1
#include <etherboot.h>
#include <nic.h>

/* #define DEBUG	1 */

struct arptable_t arptable[MAX_ARP];

/* Set if the user pushes Control-C.  */
int ip_abort = 0;
/* Set if an ethernet card is probed and IP addresses are set.  */
int network_ready = 0;

struct rom_info rom;

static int vendorext_isvalid;
static unsigned long netmask;
static struct bootpd_t bootp_data;
static unsigned long xid;
static unsigned char *end_of_rfc1533 = NULL;

#ifndef	NO_DHCP_SUPPORT
#endif /* NO_DHCP_SUPPORT */

/* 銭th */
static unsigned char vendorext_magic[] = {0xE4, 0x45, 0x74, 0x68};
static const unsigned char broadcast[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

#ifdef	NO_DHCP_SUPPORT

static unsigned char rfc1533_cookie[5] = {RFC1533_COOKIE, RFC1533_END};

#else /* ! NO_DHCP_SUPPORT */

static int dhcp_reply;
static in_addr dhcp_server = {0L};
static in_addr dhcp_addr = {0L};
static unsigned char rfc1533_cookie[] = {RFC1533_COOKIE};
static unsigned char rfc1533_end[] = {RFC1533_END};

static const unsigned char dhcpdiscover[] =
{
  RFC2132_MSG_TYPE, 1, DHCPDISCOVER,	
  RFC2132_MAX_SIZE,2,	/* request as much as we can */
  ETH_MAX_MTU / 256, ETH_MAX_MTU % 256,
  RFC2132_PARAM_LIST, 4, RFC1533_NETMASK, RFC1533_GATEWAY,
  RFC1533_HOSTNAME, RFC1533_EXTENSIONPATH
};

static const unsigned char dhcprequest[] =
{
  RFC2132_MSG_TYPE, 1, DHCPREQUEST,
  RFC2132_SRV_ID, 4, 0, 0, 0, 0,
  RFC2132_REQ_ADDR, 4, 0, 0, 0, 0,
  RFC2132_MAX_SIZE, 2,	/* request as much as we can */
  ETH_MAX_MTU / 256, ETH_MAX_MTU % 256,
  /* request parameters */
  RFC2132_PARAM_LIST,
  /* 4 standard + 2 vendortags */
  4 + 2,
  /* Standard parameters */
  RFC1533_NETMASK, RFC1533_GATEWAY,
  RFC1533_HOSTNAME, RFC1533_EXTENSIONPATH,
  /* Etherboot vendortags */
  RFC1533_VENDOR_MAGIC,
  RFC1533_VENDOR_CONFIGFILE,
};

#endif /* ! NO_DHCP_SUPPORT */

static unsigned short ipchksum (unsigned short *ip, int len);
static unsigned short udpchksum (struct iphdr *packet);

void
print_network_configuration (void)
{
  if (! eth_probe ())
    grub_printf ("No ethernet card found.\n");
  else if (! network_ready)
    grub_printf ("Not initialized yet.\n");
  else
    {
      etherboot_printf ("Address: %@\n", arptable[ARP_CLIENT].ipaddr.s_addr);
      etherboot_printf ("Netmask: %@\n", netmask);
      etherboot_printf ("Server: %@\n", arptable[ARP_SERVER].ipaddr.s_addr);
      etherboot_printf ("Gateway: %@\n", arptable[ARP_GATEWAY].ipaddr.s_addr);
    }
}


/**************************************************************************
DEFAULT_NETMASK - Return default netmask for IP address
**************************************************************************/
static inline unsigned long 
default_netmask (void)
{
  int net = ntohl (arptable[ARP_CLIENT].ipaddr.s_addr) >> 24;
  if (net <= 127)
    return (htonl (0xff000000));
  else if (net < 192)
    return (htonl (0xffff0000));
  else
    return (htonl (0xffffff00));
}

/* ifconfig - configure network interface.  */
int
ifconfig (char *ip, char *sm, char *gw, char *svr)
{
  in_addr tmp;
  
  if (sm) 
    {
      if (! inet_aton (sm, &tmp))
	return 0;
      
      netmask = tmp.s_addr;
    }
  
  if (ip) 
    {
      if (! inet_aton (ip, &arptable[ARP_CLIENT].ipaddr)) 
	return 0;
      
      if (! netmask && ! sm) 
	netmask = default_netmask ();
    }
  
  if (gw && ! inet_aton (gw, &arptable[ARP_GATEWAY].ipaddr)) 
    return 0;

  /* Clear out the ARP entry.  */
  grub_memset (arptable[ARP_GATEWAY].node, 0, ETH_ALEN);
  
  if (svr && ! inet_aton (svr, &arptable[ARP_SERVER].ipaddr)) 
    return 0;

  /* Likewise.  */
  grub_memset (arptable[ARP_SERVER].node, 0, ETH_ALEN);
  
  if (ip || sm)
    {
      if (IP_BROADCAST == (netmask | arptable[ARP_CLIENT].ipaddr.s_addr)
	  || netmask == (netmask | arptable[ARP_CLIENT].ipaddr.s_addr)
	  || ! netmask)
	network_ready = 0;
      else
	network_ready = 1;
    }
  
  return 1;
}


/**************************************************************************
UDP_TRANSMIT - Send a UDP datagram
**************************************************************************/
int 
udp_transmit (unsigned long destip, unsigned int srcsock,
	      unsigned int destsock, int len, const void *buf)
{
  struct iphdr *ip;
  struct udphdr *udp;
  struct arprequest arpreq;
  int arpentry, i;
  int retry;

  ip = (struct iphdr *) buf;
  udp = (struct udphdr *) ((unsigned long) buf + sizeof (struct iphdr));
  ip->verhdrlen = 0x45;
  ip->service = 0;
  ip->len = htons (len);
  ip->ident = 0;
  ip->frags = 0;
  ip->ttl = 60;
  ip->protocol = IP_UDP;
  ip->chksum = 0;
  ip->src.s_addr = arptable[ARP_CLIENT].ipaddr.s_addr;
  ip->dest.s_addr = destip;
  ip->chksum = ipchksum ((unsigned short *) buf, sizeof (struct iphdr));
  udp->src = htons (srcsock);
  udp->dest = htons (destsock);
  udp->len = htons (len - sizeof (struct iphdr));
  udp->chksum = 0;
  udp->chksum = htons (udpchksum (ip));

  if (udp->chksum == 0)
    udp->chksum = 0xffff;
  
  if (destip == IP_BROADCAST)
    {
      eth_transmit (broadcast, IP, len, buf);
    }
  else
    {
      if (((destip & netmask)
	   != (arptable[ARP_CLIENT].ipaddr.s_addr & netmask))
	  && arptable[ARP_GATEWAY].ipaddr.s_addr)
	destip = arptable[ARP_GATEWAY].ipaddr.s_addr;
      
      for (arpentry = 0; arpentry < MAX_ARP; arpentry++)
	if (arptable[arpentry].ipaddr.s_addr == destip)
	  break;
      
      if (arpentry == MAX_ARP)
	{
	  etherboot_printf ("%@ is not in my arp table!\n", destip);
	  return 0;
	}
      
      for (i = 0; i < ETH_ALEN; i++)
	if (arptable[arpentry].node[i])
	  break;
      
      if (i == ETH_ALEN)
	{
	  /* Need to do arp request.  */
#ifdef DEBUG
	  grub_printf ("arp request.\n");
#endif
	  arpreq.hwtype = htons (1);
	  arpreq.protocol = htons (IP);
	  arpreq.hwlen = ETH_ALEN;
	  arpreq.protolen = 4;
	  arpreq.opcode = htons (ARP_REQUEST);
	  grub_memmove (arpreq.shwaddr, arptable[ARP_CLIENT].node,
			ETH_ALEN);
	  grub_memmove (arpreq.sipaddr, (char *) &arptable[ARP_CLIENT].ipaddr,
			sizeof (in_addr));
	  grub_memset (arpreq.thwaddr, 0, ETH_ALEN);
	  grub_memmove (arpreq.tipaddr, (char *) &destip, sizeof (in_addr));
	  
	  for (retry = 1; retry <= MAX_ARP_RETRIES; retry++)
	    {
	      long timeout;
	      
	      eth_transmit (broadcast, ARP, sizeof (arpreq), &arpreq);
	      timeout = rfc2131_sleep_interval (TIMEOUT, retry);
	      
	      if (await_reply (AWAIT_ARP, arpentry, arpreq.tipaddr, timeout))
		goto xmit;

	      if (ip_abort)
		return 0;
	    }
	  
	  return 0;
	}
      
    xmit:
      eth_transmit (arptable[arpentry].node, IP, len, buf);
    }
  
  return 1;
}

/**************************************************************************
TFTP - Download extended BOOTP data, or kernel image
**************************************************************************/
static int
tftp (const char *name, int (*fnc) (unsigned char *, int, int, int))
{
  int retry = 0;
  static unsigned short iport = 2000;
  unsigned short oport = 0;
  unsigned short len, block = 0, prevblock = 0;
  int bcounter = 0;
  struct tftp_t *tr;
  struct tftpreq_t tp;
  int rc;
  int packetsize = TFTP_DEFAULTSIZE_PACKET;
  
  /* Clear out the Rx queue first.  It contains nothing of interest,
   * except possibly ARP requests from the DHCP/TFTP server.  We use
   * polling throughout Etherboot, so some time may have passed since we
   * last polled the receive queue, which may now be filled with
   * broadcast packets.  This will cause the reply to the packets we are
   * about to send to be lost immediately.  Not very clever.  */
  await_reply (AWAIT_QDRAIN, 0, NULL, 0);
  
  tp.opcode = htons (TFTP_RRQ);
  len = (grub_sprintf ((char *) tp.u.rrq, "%s%coctet%cblksize%c%d",
		       name, 0, 0, 0, TFTP_MAX_PACKET)
	 + sizeof (tp.ip) + sizeof (tp.udp) + sizeof (tp.opcode) + 1);
  if (! udp_transmit (arptable[ARP_SERVER].ipaddr.s_addr, ++iport,
		      TFTP_PORT, len, &tp))
    return 0;
  
  for (;;)
    {
      long timeout;
      
#ifdef CONGESTED
      timeout = rfc2131_sleep_interval (block ? TFTP_REXMT : TIMEOUT, retry);
#else
      timeout = rfc2131_sleep_interval (TIMEOUT, retry);
#endif

      if (! await_reply (AWAIT_TFTP, iport, NULL, timeout))
	{
	  if (! block && retry++ < MAX_TFTP_RETRIES)
	    {
	      /* Maybe initial request was lost.  */
	      if (! udp_transmit (arptable[ARP_SERVER].ipaddr.s_addr,
				  ++iport, TFTP_PORT, len, &tp))
		return 0;
	      
	      continue;
	    }
	  
#ifdef CONGESTED
	  if (block && ((retry += TFTP_REXMT) < TFTP_TIMEOUT))
	    {
	      /* We resend our last ack.  */
#ifdef MDEBUG
	      grub_printf ("<REXMT>\n");
#endif
	      udp_transmit (arptable[ARP_SERVER].ipaddr.s_addr,
			    iport, oport,
			    TFTP_MIN_PACKET, &tp);
	      continue;
	    }
#endif
	  /* Timeout.  */
	  break;
	}
      
      tr = (struct tftp_t *) &nic.packet[ETH_HLEN];
      if (tr->opcode == ntohs (TFTP_ERROR))
	{
	  grub_printf ("TFTP error %d (%s)\n",
		       ntohs (tr->u.err.errcode),
		       tr->u.err.errmsg);
	  break;
	}
      
      if (tr->opcode == ntohs (TFTP_OACK))
	{
	  char *p = tr->u.oack.data, *e;
	  
	  /* Shouldn't happen.  */
	  if (prevblock)
	    /* Ignore it.  */
	    continue;
	  
	  len = ntohs (tr->udp.len) - sizeof (struct udphdr) - 2;
	  if (len > TFTP_MAX_PACKET)
	    goto noak;
	  
	  e = p + len;
	  while (*p != '\000' && p < e)
	    {