text: /*
   *  $Id: ipconfig.c,v 1.34 2000/07/26 01:04:18 davem Exp $
   *
   *  Automatic Configuration of IP -- use BOOTP or RARP or user-supplied
   *  information to configure own IP address and routes.
   *
   *  Copyright (C) 1996--1998 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
   *
   *  Derived from network configuration code in fs/nfs/nfsroot.c,
   *  originally Copyright (C) 1995, 1996 Gero Kuhlmann and me.
   *
   *  BOOTP rewritten to construct and analyse packets itself instead
   *  of misusing the IP layer. num_bugs_causing_wrong_arp_replies--;
   *					     -- MJ, December 1998
   *  
   *  Fixed ip_auto_config_setup calling at startup in the new "Linker Magic"
   *  initialization scheme.
   *	- Arnaldo Carvalho de Melo <acme@conectiva.com.br>, 08/11/1999
   */
  
  #include <linux/config.h>
  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/random.h>
  #include <linux/init.h>
  #include <linux/utsname.h>
  #include <linux/in.h>
  #include <linux/if.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <linux/if_arp.h>
  #include <linux/skbuff.h>
  #include <linux/ip.h>
  #include <linux/socket.h>
  #include <linux/route.h>
  #include <linux/udp.h>
  #include <net/arp.h>
  #include <net/ip.h>
  #include <net/ipconfig.h>
  
  #include <asm/uaccess.h>
  #include <asm/checksum.h>
  
  /* Define this to allow debugging output */
  #undef IPCONFIG_DEBUG
  
  #ifdef IPCONFIG_DEBUG
  #define DBG(x) printk x
  #else
  #define DBG(x) do { } while(0)
  #endif
  
  /* Define the timeout for waiting for a RARP/BOOTP reply */
  #define CONF_BASE_TIMEOUT	(HZ*5)	/* Initial timeout: 5 seconds */
  #define CONF_RETRIES	 	10	/* 10 retries */
  #define CONF_TIMEOUT_RANDOM	(HZ)	/* Maximum amount of randomization */
  #define CONF_TIMEOUT_MULT	*5/4	/* Rate of timeout growth */
  #define CONF_TIMEOUT_MAX	(HZ*30)	/* Maximum allowed timeout */
  
  /* IP configuration */
  static char user_dev_name[IFNAMSIZ] __initdata = { 0, };/* Name of user-selected boot device */
  u32 ic_myaddr __initdata = INADDR_NONE;		/* My IP address */
  u32 ic_servaddr __initdata = INADDR_NONE;	/* Server IP address */
  u32 ic_gateway __initdata = INADDR_NONE;	/* Gateway IP address */
  u32 ic_netmask __initdata = INADDR_NONE;	/* Netmask for local subnet */
  int ic_enable __initdata = 1;			/* Automatic IP configuration enabled */
  int ic_host_name_set __initdata = 0;		/* Host name configured manually */
  int ic_set_manually __initdata = 0;		/* IPconfig parameters set manually */
  
  u32 root_server_addr __initdata = INADDR_NONE;		/* Address of boot server */
  u8 root_server_path[256] __initdata = { 0, };		/* Path to mount as root */
  
  #if defined(CONFIG_IP_PNP_BOOTP) || defined(CONFIG_IP_PNP_RARP)
  
  #define CONFIG_IP_PNP_DYNAMIC
  
  int ic_proto_enabled __initdata = 0			/* Protocols enabled */
  #ifdef CONFIG_IP_PNP_BOOTP
  			| IC_BOOTP
  #endif
  #ifdef CONFIG_IP_PNP_RARP
  			| IC_RARP
  #endif
  			;
  static int ic_got_reply __initdata = 0;				/* Protocol(s) we got reply from */
  
  #else
  
  static int ic_proto_enabled __initdata = 0;
  
  #endif
  
  static int ic_proto_have_if __initdata = 0;
  
  /*
   *	Network devices
   */
  
  struct ic_device {
  	struct ic_device *next;
  	struct net_device *dev;
  	unsigned short flags;
  	int able;
  };
  
  static struct ic_device *ic_first_dev __initdata = NULL;/* List of open device */
  static struct net_device *ic_dev __initdata = NULL;		/* Selected device */
  
  static int __init ic_open_devs(void)
  {
  	struct ic_device *d, **last;
  	struct net_device *dev;
  	unsigned short oflags;
  
  	last = &ic_first_dev;
  	rtnl_shlock();
  	for (dev = dev_base; dev; dev = dev->next) {
  		if (user_dev_name[0] ? !strcmp(dev->name, user_dev_name) :
  		    (!(dev->flags & IFF_LOOPBACK) &&
  		     (dev->flags & (IFF_POINTOPOINT|IFF_BROADCAST)) &&
  		     strncmp(dev->name, "dummy", 5))) {
  			int able = 0;
  			if (dev->mtu >= 364)
  				able |= IC_BOOTP;
  			else
  				printk(KERN_WARNING "BOOTP: Ignoring device %s, MTU %d too small", dev->name, dev->mtu);
  			if (!(dev->flags & IFF_NOARP))
  				able |= IC_RARP;
  			able &= ic_proto_enabled;
  			if (ic_proto_enabled && !able)
  				continue;
  			oflags = dev->flags;
  			if (dev_change_flags(dev, oflags | IFF_UP) < 0) {
  				printk(KERN_ERR "IP-Config: Failed to open %s\n", dev->name);
  				continue;
  			}
  			if (!(d = kmalloc(sizeof(struct ic_device), GFP_KERNEL)))
  				return -1;
  			d->dev = dev;
  			*last = d;
  			last = &d->next;
  			d->flags = oflags;
  			d->able = able;
  			ic_proto_have_if |= able;
  			DBG(("IP-Config: Opened %s (able=%d)\n", dev->name, able));
  		}
  	}
  	rtnl_shunlock();
  
  	*last = NULL;
  
  	if (!ic_first_dev) {
  		if (user_dev_name[0])
  			printk(KERN_ERR "IP-Config: Device `%s' not found.\n", user_dev_name);
  		else
  			printk(KERN_ERR "IP-Config: No network devices available.\n");
  		return -1;
  	}
  	return 0;
  }
  
  static void __init ic_close_devs(void)
  {
  	struct ic_device *d, *next;
  	struct net_device *dev;
  
  	rtnl_shlock();
  	next = ic_first_dev;
  	while ((d = next)) {
  		next = d->next;
  		dev = d->dev;
  		if (dev != ic_dev) {
  			DBG(("IP-Config: Downing %s\n", dev->name));
  			dev_change_flags(dev, d->flags);
  		}
  		kfree(d);
  	}
  	rtnl_shunlock();
  }
  
  /*
   *	Interface to various network functions.
   */
  
  static inline void
  set_sockaddr(struct sockaddr_in *sin, u32 addr, u16 port)
  {
  	sin->sin_family = AF_INET;
  	sin->sin_addr.s_addr = addr;
  	sin->sin_port = port;
  }
  
  static int __init ic_dev_ioctl(unsigned int cmd, struct ifreq *arg)
  {
  	int res;
  
  	mm_segment_t oldfs = get_fs();
  	set_fs(get_ds());
  	res = devinet_ioctl(cmd, arg);
  	set_fs(oldfs);
  	return res;
  }
  
  static int __init ic_route_ioctl(unsigned int cmd, struct rtentry *arg)
  {
  	int res;
  
  	mm_segment_t oldfs = get_fs();
  	set_fs(get_ds());
  	res = ip_rt_ioctl(cmd, arg);
  	set_fs(oldfs);
  	return res;
  }
  
  /*
   *	Set up interface addresses and routes.
   */
  
  static int __init ic_setup_if(void)
  {
  	struct ifreq ir;
  	struct sockaddr_in *sin = (void *) &ir.ifr_ifru.ifru_addr;
  	int err;
  
  	memset(&ir, 0, sizeof(ir));
  	strcpy(ir.ifr_ifrn.ifrn_name, ic_dev->name);
  	set_sockaddr(sin, ic_myaddr, 0);
  	if ((err = ic_dev_ioctl(SIOCSIFADDR, &ir)) < 0) {
  		printk(KERN_ERR "IP-Config: Unable to set interface address (%d).\n", err);
  		return -1;
  	}
  	set_sockaddr(sin, ic_netmask, 0);
  	if ((err = ic_dev_ioctl(SIOCSIFNETMASK, &ir)) < 0) {
  		printk(KERN_ERR "IP-Config: Unable to set interface netmask (%d).\n", err);
  		return -1;
  	}
  	set_sockaddr(sin, ic_myaddr | ~ic_netmask, 0);
  	if ((err = ic_dev_ioctl(SIOCSIFBRDADDR, &ir)) < 0) {
  		printk(KERN_ERR "IP-Config: Unable to set interface broadcast address (%d).\n", err);
  		return -1;
  	}
  	return 0;
  }
  
  static int __init ic_setup_routes(void)
  {
  	/* No need to setup device routes, only the default route... */
  
  	if (ic_gateway != INADDR_NONE) {
  		struct rtentry rm;
  		int err;
  
  		memset(&rm, 0, sizeof(rm));
  		if ((ic_gateway ^ ic_myaddr) & ic_netmask) {
  			printk(KERN_ERR "IP-Config: Gateway not on directly connected network.\n");
  			return -1;
  		}
  		set_sockaddr((struct sockaddr_in *) &rm.rt_dst, 0, 0);
  		set_sockaddr((struct sockaddr_in *) &rm.rt_genmask, 0, 0);
  		set_sockaddr((struct sockaddr_in *) &rm.rt_gateway, ic_gateway, 0);
  		rm.rt_flags = RTF_UP | RTF_GATEWAY;
  		if ((err = ic_route_ioctl(SIOCADDRT, &rm)) < 0) {
  			printk(KERN_ERR "IP-Config: Cannot add default route (%d).\n", err);
  			return -1;
  		}
  	}
  
  	return 0;
  }
  
  /*
   *	Fill in default values for all missing parameters.
   */
  
  static int __init ic_defaults(void)
  {
  	/*
  	 *	At this point we have no userspace running so need not
  	 *	claim locks on system_utsname
  	 */
  	 
  	if (!ic_host_name_set)
  		strcpy(system_utsname.nodename, in_ntoa(ic_myaddr));
  
  	if (root_server_addr == INADDR_NONE)
  		root_server_addr = ic_servaddr;
  
  	if (ic_netmask == INADDR_NONE) {
  		if (IN_CLASSA(ntohl(ic_myaddr)))
  			ic_netmask = htonl(IN_CLASSA_NET);
  		else if (IN_CLASSB(ntohl(ic_myaddr)))
  			ic_netmask = htonl(IN_CLASSB_NET);
  		else if (IN_CLASSC(ntohl(ic_myaddr)))
  			ic_netmask = htonl(IN_CLASSC_NET);
  		else {
  			printk(KERN_ERR "IP-Config: Unable to guess netmask for address %u.%u.%u.%u\n",
  				NIPQUAD(ic_myaddr));
  			return -1;
  		}
  		printk("IP-Config: Guessing netmask %u.%u.%u.%u\n", NIPQUAD(ic_netmask));
  	}
  
  	return 0;
  }
  
  /*
   *	RARP support.
   */
  
  #ifdef CONFIG_IP_PNP_RARP
  
  static int ic_rarp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt);
  
  static struct packet_type rarp_packet_type __initdata = {
  	__constant_htons(ETH_P_RARP),
  	NULL,			/* Listen to all devices */
  	ic_rarp_recv,
  	NULL,
  	NULL
  };
  
  static inline void ic_rarp_init(void)
  {
  	dev_add_pack(&rarp_packet_type);
  }
  
  static inline void ic_rarp_cleanup(void)
  {
  	dev_remove_pack(&rarp_packet_type);
  }
  
  /*
   *  Process received RARP packet.
   */
  static int __init
  ic_rarp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
  {
  	struct arphdr *rarp = (struct arphdr *)skb->h.raw;
  	unsigned char *rarp_ptr = (unsigned char *) (rarp + 1);
  	unsigned long sip, tip;
  	unsigned char *sha, *tha;		/* s for "source", t for "target" */
  
  	/* If we already have a reply, just drop the packet */
  	if (ic_got_reply)
  		goto drop;
  
  	/* If this test doesn't pass, it's not IP, or we should ignore it anyway */
  	if (rarp->ar_hln != dev->addr_len || dev->type != ntohs(rarp->ar_hrd))
  		goto drop;
  
  	/* If it's not a RARP reply, delete it. */
  	if (rarp->ar_op != htons(ARPOP_RREPLY))
  		goto drop;
  
  	/* If it's not Ethernet, delete it. */
  	if (rarp->ar_pro != htons(ETH_P_IP))
  		goto drop;
  
  	/* Extract variable-width fields */
  	sha = rarp_ptr;
  	rarp_ptr += dev->addr_len;
  	memcpy(&sip, rarp_ptr, 4);
  	rarp_ptr += 4;
  	tha = rarp_ptr;
  	rarp_ptr += dev->addr_len;
  	memcpy(&tip, rarp_ptr, 4);
  
  	/* Discard packets which are not meant for us. */
  	if (memcmp(tha, dev->dev_addr, dev->addr_len))
  		goto drop;
  
  	/* Discard packets which are not from specified server. */
  	if (ic_servaddr != INADDR_NONE && ic_servaddr != sip)
  		goto drop;
  
  	/* Victory! The packet is what we were looking for! */
  	if (!ic_got_reply) {
  		ic_got_reply = IC_RARP;
  		ic_dev = dev;
  		if (ic_myaddr == INADDR_NONE)
  			ic_myaddr = tip;
  		ic_servaddr = sip;
  	}
  
  	/* And throw the packet out... */
  drop:
  	kfree_skb(skb);
  	return 0;
  }
  
  
  /*
   *  Send RARP request packet over all devices which allow RARP.
   */
  static void __init ic_rarp_send(void)
  {
  	struct ic_device *d;
  
  	for (d=ic_first_dev; d; d=d->next)
  		if (d->able & IC_RARP) {
  			struct net_device *dev = d->dev;
  			arp_send(ARPOP_RREQUEST, ETH_P_RARP, 0, dev, 0, NULL,
  				 dev->dev_addr, dev->dev_addr);
  		}
  }
  
  #endif
  
  /*
   *	BOOTP support.
   */
  
  #ifdef CONFIG_IP_PNP_BOOTP
  
  struct bootp_pkt {		/* BOOTP packet format */
  	struct iphdr iph;	/* IP header */
  	struct udphdr udph;	/* UDP header */
  	u8 op;			/* 1=request, 2=reply */
  	u8 htype;		/* HW address type */
  	u8 hlen;		/* HW address length */
  	u8 hops;		/* Used only by gateways */
  	u32 xid;		/* Transaction ID */
  	u16 secs;		/* Seconds since we started */
  	u16 flags;		/* Just what it says */
  	u32 client_ip;		/* Client's IP address if known */
  	u32 your_ip;		/* Assigned IP address */
  	u32 server_ip;		/* Server's IP address */
  	u32 relay_ip;		/* IP address of BOOTP relay */
  	u8 hw_addr[16];		/* Client's HW address */
  	u8 serv_name[64];	/* Server host name */
  	u8 boot_file[128];	/* Name of boot file */
  	u8 vendor_area[128];	/* Area for extensions */
  };
  
  #define BOOTP_REQUEST 1
  #define BOOTP_REPLY 2
  
  static u32 ic_bootp_xid;
  
  static int ic_bootp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt);
  
  static struct packet_type bootp_packet_type __initdata = {
  	__constant_htons(ETH_P_IP),
  	NULL,			/* Listen to all devices */
  	ic_bootp_recv,
  	NULL,
  	NULL
  };
  
  
  /*
   *  Initialize BOOTP extension fields in the request.
   */
  static void __init ic_bootp_init_ext(u8 *e)
  {
  	*e++ = 99;		/* RFC1048 Magic Cookie */
  	*e++ = 130;
  	*e++ = 83;
  	*e++ = 99;
  	*e++ = 1;		/* Subnet mask request */
  	*e++ = 4;
  	e += 4;
  	*e++ = 3;		/* Default gateway request */
  	*e++ = 4;
  	e += 4;
  	*e++ = 12;		/* Host name request */
  	*e++ = 32;
  	e += 32;
  	*e++ = 40;		/* NIS Domain name request */
  	*e++ = 32;
  	e += 32;
  	*e++ = 17;		/* Boot path */
  	*e++ = 32;
  	e += 32;
  	*e = 255;		/* End of the list */
  }
  
  
  /*
   *  Initialize the BOOTP mechanism.
   */
  static inline void ic_bootp_init(void)
  {
  	get_random_bytes(&ic_bootp_xid, sizeof(u32));
  	DBG(("BOOTP: XID=%08x\n", ic_bootp_xid));
  	dev_add_pack(&bootp_packet_type);
  }
  
  
  /*
   *  BOOTP cleanup.
   */
  static inline void ic_bootp_cleanup(void)
  {
  	dev_remove_pack(&bootp_packet_type);
  }
  
  
  /*
   *  Send BOOTP request to single interface.
   */
  static void __init ic_bootp_send_if(struct ic_device *d, u32 jiffies)
  {
  	struct net_device *dev = d->dev;
  	struct sk_buff *skb;
  	struct bootp_pkt *b;
  	int hh_len = (dev->hard_header_len + 15) & ~15;
  	struct iphdr *h;
  
  	/* Allocate packet */
  	skb = alloc_skb(sizeof(struct bootp_pkt) + hh_len + 15, GFP_KERNEL);
  	if (!skb)
  		return;
  	skb_reserve(skb, hh_len);
  	b = (struct bootp_pkt *) skb_put(skb, sizeof(struct bootp_pkt));
  	memset(b, 0, sizeof(struct bootp_pkt));
  
  	/* Construct IP header */
  	skb->nh.iph = h = &b->iph;
  	h->version = 4;
  	h->ihl = 5;
  	h->tot_len = htons(sizeof(struct bootp_pkt));
  	h->frag_off = htons(IP_DF);
  	h->ttl = 64;
  	h->protocol = IPPROTO_UDP;
  	h->daddr = INADDR_BROADCAST;
  	h->check = ip_fast_csum((unsigned char *) h, h->ihl);
  
  	/* Construct UDP header */
  	b->udph.source = htons(68);
  	b->udph.dest = htons(67);
  	b->udph.len = htons(sizeof(struct bootp_pkt) - sizeof(struct iphdr));
  	/* UDP checksum not calculated -- explicitly allowed in BOOTP RFC */
  
  	/* Construct BOOTP header */
  	b->op = BOOTP_REQUEST;
  	if (dev->type < 256) /* check for false types */
  		b->htype = dev->type;
  	else if (dev->type == ARPHRD_IEEE802_TR) /* fix for token ring */
  		b->htype = ARPHRD_IEEE802;
  	else {
  		printk("Unknown ARP type 0x%04x for device %s\n", dev->type, dev->name);
  		b->htype = dev->type; /* can cause undefined behavior */
  	}
  	b->hlen = dev->addr_len;
  	memcpy(b->hw_addr, dev->dev_addr, dev->addr_len);
  	b->secs = htons(jiffies / HZ);
  	b->xid = ic_bootp_xid;
  	ic_bootp_init_ext(b->vendor_area);
  
  	/* Chain packet down the line... */
  	skb->dev = dev;
  	skb->protocol = __constant_htons(ETH_P_IP);
  	if ((dev->hard_header &&
  	     dev->hard_header(skb, dev, ntohs(skb->protocol), dev->broadcast, dev->dev_addr, skb->len) < 0) ||
  	    dev_queue_xmit(skb) < 0)
  		printk("E");
  }
  
  
  /*
   *  Send BOOTP requests to all interfaces.
   */
  static void __init ic_bootp_send(u32 jiffies)
  {
  	struct ic_device *d;
  
  	for(d=ic_first_dev; d; d=d->next)
  		if (d->able & IC_BOOTP)
  			ic_bootp_send_if(d, jiffies);
  }
  
  
  /*
   *  Copy BOOTP-supplied string if not already set.
   */
  static int __init ic_bootp_string(char *dest, char *src, int len, int max)
  {
  	if (!len)
  		return 0;
  	if (len > max-1)
  		len = max-1;
  	strncpy(dest, src, len);
  	dest[len] = '\0';
  	return 1;
  }
  
  
  /*
   *  Process BOOTP extension.
   */
  static void __init ic_do_bootp_ext(u8 *ext)
  {
  #ifdef IPCONFIG_DEBUG
  	u8 *c;
  
  	printk("BOOTP: Got extension %02x",*ext);
  	for(c=ext+2; c<ext+2+ext[1]; c++)
  		printk(" %02x", *c);
  	printk("\n");
  #endif
  
  	switch (*ext++) {
  		case 1:		/* Subnet mask */
  			if (ic_netmask == INADDR_NONE)
  				memcpy(&ic_netmask, ext+1, 4);
  			break;
  		case 3:		/* Default gateway */
  			if (ic_gateway == INADDR_NONE)
  				memcpy(&ic_gateway, ext+1, 4);
  			break;
  		case 12:	/* Host name */
  			ic_bootp_string(system_utsname.nodename, ext+1, *ext, __NEW_UTS_LEN);
  			ic_host_name_set = 1;
  			break;
  		case 40:	/* NIS Domain name */
  			ic_bootp_string(system_utsname.domainname, ext+1, *ext, __NEW_UTS_LEN);
  			break;
  		case 17:	/* Root path */
  			if (!root_server_path[0])
  				ic_bootp_string(root_server_path, ext+1, *ext, sizeof(root_server_path));
  			break;
  	}
  }
  
  
  /*
   *  Receive BOOTP reply.
   */
  static int __init ic_bootp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
  {
  	struct bootp_pkt *b = (struct bootp_pkt *) skb->nh.iph;
  	struct iphdr *h = &b->iph;
  	int len;
  
  	/* If we already have a reply, just drop the packet */
  	if (ic_got_reply)
  		goto drop;
  
  	/* Check whether it's a BOOTP packet */
  	if (skb->pkt_type == PACKET_OTHERHOST ||
  	    skb->len < sizeof(struct udphdr) + sizeof(struct iphdr) ||
  	    h->ihl != 5 ||
  	    h->version != 4 ||
  	    ip_fast_csum((char *) h, h->ihl) != 0 ||
  	    skb->len < ntohs(h->tot_len) ||
  	    h->protocol != IPPROTO_UDP ||
  	    b->udph.source != htons(67) ||
  	    b->udph.dest != htons(68) ||
  	    ntohs(h->tot_len) < ntohs(b->udph.len) + sizeof(struct iphdr))
  		goto drop;
  
  	/* Fragments are not supported */
  	if (h->frag_off & htons(IP_OFFSET|IP_MF)) {
  		printk(KERN_ERR "BOOTP: Ignoring fragmented reply.\n");
  		goto drop;
  	}
  
  	/* Is it a reply to our BOOTP request? */
  	len = ntohs(b->udph.len) - sizeof(struct udphdr);
  	if (len < 300 ||				    /* See RFC 951:2.1 */
  	    b->op != BOOTP_REPLY ||
  	    b->xid != ic_bootp_xid) {
  		printk("?");
  		goto drop;
  	}
  
  	/* Extract basic fields */
  	ic_myaddr = b->your_ip;
  	ic_servaddr = b->server_ip;
  	ic_got_reply = IC_BOOTP;
  	ic_dev = dev;
  
  	/* Parse extensions */
  	if (b->vendor_area[0] == 99 &&	/* Check magic cookie */
  	    b->vendor_area[1] == 130 &&
  	    b->vendor_area[2] == 83 &&
  	    b->vendor_area[3] == 99) {
  		u8 *ext = &b->vendor_area[4];
                  u8 *end = (u8 *) b + ntohs(b->iph.tot_len);
  		while (ext < end && *ext != 0xff) {
  			if (*ext == 0)		/* Padding */
  				ext++;
  			else {
  				u8 *opt = ext;
  				ext += ext[1] + 2;
  				if (ext <= end)
  					ic_do_bootp_ext(opt);
  			}
  		}
  	}
  
  	if (ic_gateway == INADDR_NONE && b->relay_ip)
  		ic_gateway = b->relay_ip;
  
  drop:
  	kfree_skb(skb);
  	return 0;
  }	
  
  
  #endif
  
  
  /*
   *	Dynamic IP configuration -- BOOTP and RARP.
   */
  
  #ifdef CONFIG_IP_PNP_DYNAMIC
  
  static int __init ic_dynamic(void)
  {
  	int retries;
  	unsigned long timeout, jiff;
  	unsigned long start_jiffies;
  	int do_rarp = ic_proto_have_if & IC_RARP;
  	int do_bootp = ic_proto_have_if & IC_BOOTP;
  
  	/*
  	 * If neither BOOTP nor RARP was selected, return with an error. This
  	 * routine gets only called when some pieces of information are mis-
  	 * sing, and without BOOTP and RARP we are not able to get that in-
  	 * formation.
  	 */
  	if (!ic_proto_enabled) {
  		printk(KERN_ERR "IP-Config: Incomplete network configuration information.\n");
  		return -1;
  	}
  
  #ifdef CONFIG_IP_PNP_BOOTP
  	if ((ic_proto_enabled ^ ic_proto_have_if) & IC_BOOTP)
  		printk(KERN_ERR "BOOTP: No suitable device found.\n");
  #endif
  
  #ifdef CONFIG_IP_PNP_RARP
  	if ((ic_proto_enabled ^ ic_proto_have_if) & IC_RARP)
  		printk(KERN_ERR "RARP: No suitable device found.\n");
  #endif
  
  	if (!ic_proto_have_if)
  		/* Error message already printed */
  		return -1;
  
  	/*
  	 * Setup RARP and BOOTP protocols
  	 */
  #ifdef CONFIG_IP_PNP_RARP
  	if (do_rarp)
  		ic_rarp_init();
  #endif
  #ifdef CONFIG_IP_PNP_BOOTP
  	if (do_bootp)
  		ic_bootp_init();
  #endif
  
  	/*
  	 * Send requests and wait, until we get an answer. This loop
  	 * seems to be a terrible waste of CPU time, but actually there is
  	 * only one process running at all, so we don't need to use any
  	 * scheduler functions.
  	 * [Actually we could now, but the nothing else running note still 
  	 *  applies.. - AC]
  	 */
  	printk(KERN_NOTICE "Sending %s%s%s requests...",
  	        do_bootp ? "BOOTP" : "",
  		do_bootp && do_rarp ? " and " : "",
  		do_rarp ? "RARP" : "");
  	start_jiffies = jiffies;
  	retries = CONF_RETRIES;
  	get_random_bytes(&timeout, sizeof(timeout));
  	timeout = CONF_BASE_TIMEOUT + (timeout % (unsigned) CONF_TIMEOUT_RANDOM);
  	for(;;) {
  #ifdef CONFIG_IP_PNP_BOOTP
  		if (do_bootp)
  			ic_bootp_send(jiffies - start_jiffies);
  #endif
  #ifdef CONFIG_IP_PNP_RARP
  		if (do_rarp)
  			ic_rarp_send();
  #endif
  		printk(".");
  		jiff = jiffies + timeout;
  		while (jiffies < jiff && !ic_got_reply)
  			barrier();
  		if (ic_got_reply) {
  			printk(" OK\n");
  			break;
  		}
  		if (! --retries) {
  			printk(" timed out!\n");
  			break;
  		}
  		timeout = timeout CONF_TIMEOUT_MULT;
  		if (timeout > CONF_TIMEOUT_MAX)
  			timeout = CONF_TIMEOUT_MAX;
  	}
  
  #ifdef CONFIG_IP_PNP_RARP
  	if (do_rarp)
  		ic_rarp_cleanup();
  #endif
  #ifdef CONFIG_IP_PNP_BOOTP
  	if (do_bootp)
  		ic_bootp_cleanup();
  #endif
  
  	if (!ic_got_reply)
  		return -1;
  
  	printk("IP-Config: Got %s answer from %u.%u.%u.%u, ",
  		(ic_got_reply & IC_BOOTP) ? "BOOTP" : "RARP",
  		NIPQUAD(ic_servaddr));
  	printk("my address is %u.%u.%u.%u\n", NIPQUAD(ic_myaddr));
  
  	return 0;
  }
  
  #endif
  
  /*
   *	IP Autoconfig dispatcher.
   */
  
  static int __init ip_auto_config(void)
  {
  	if (!ic_enable)
  		return 0;
  
  	DBG(("IP-Config: Entered.\n"));
  
  	/* Setup all network devices */
  	if (ic_open_devs() < 0)
  		return -1;
  
  	/*
  	 * If the config information is insufficient (e.g., our IP address or
  	 * IP address of the boot server is missing or we have multiple network
  	 * interfaces and no default was set), use BOOTP or RARP to get the
  	 * missing values.
  	 */
  	if (ic_myaddr == INADDR_NONE ||
  #ifdef CONFIG_ROOT_NFS
  	    (root_server_addr == INADDR_NONE && ic_servaddr == INADDR_NONE) ||
  #endif
  	    ic_first_dev->next) {
  #ifdef CONFIG_IP_PNP_DYNAMIC
  		if (ic_dynamic() < 0) {
  			printk(KERN_ERR "IP-Config: Auto-configuration of network failed.\n");
  			ic_close_devs();
  			return -1;
  		}
  #else
  		printk(KERN_ERR "IP-Config: Incomplete network configuration information.\n");
  		ic_close_devs();
  		return -1;
  #endif
  	} else {
  		ic_dev = ic_first_dev->dev;	/* Device selected manually or only one device -> use it */
  	}
  
  	/*
  	 * Use defaults whereever applicable.
  	 */
  	if (ic_defaults() < 0)
  		return -1;
  
  	/*
  	 * Close all network devices except the device we've
  	 * autoconfigured and set up routes.
  	 */
  	ic_close_devs();
  	if (ic_setup_if() < 0 || ic_setup_routes() < 0)
  		return -1;
  
  	DBG(("IP-Config: device=%s, local=%08x, server=%08x, boot=%08x, gw=%08x, mask=%08x\n",
  	    ic_dev->name, ic_myaddr, ic_servaddr, root_server_addr, ic_gateway, ic_netmask));
  	DBG(("IP-Config: host=%s, domain=%s, path=`%s'\n", system_utsname.nodename,
  	    system_utsname.domainname, root_server_path));
  	return 0;
  }
  
  module_init(ip_auto_config);
  
  
  /*
   *  Decode any IP configuration options in the "ip=" or "nfsaddrs=" kernel
   *  command line parameter. It consists of option fields separated by colons in
   *  the following order:
   *
   *  <client-ip>:<server-ip>:<gw-ip>:<netmask>:<host name>:<device>:<bootp|rarp>
   *
   *  Any of the fields can be empty which means to use a default value:
   *	<client-ip>	- address given by BOOTP or RARP
   *	<server-ip>	- address of host returning BOOTP or RARP packet
   *	<gw-ip>		- none, or the address returned by BOOTP
   *	<netmask>	- automatically determined from <client-ip>, or the
   *			  one returned by BOOTP
   *	<host name>	- <client-ip> in ASCII notation, or the name returned
   *			  by BOOTP
   *	<device>	- use all available devices
   *	<bootp|rarp|both|off> - use both protocols to determine my own address
   */
  static int __init ic_proto_name(char *name)
  {
  	if (!strcmp(name, "off")) {
  		ic_proto_enabled = 0;
  		return 1;
  	}
  #ifdef CONFIG_IP_PNP_BOOTP
  	else if (!strcmp(name, "bootp")) {
  		ic_proto_enabled &= ~IC_RARP;
  		return 1;
  	}
  #endif
  #ifdef CONFIG_IP_PNP_RARP
  	else if (!strcmp(name, "rarp")) {
  		ic_proto_enabled &= ~IC_BOOTP;
  		return 1;
  	}
  #endif
  #ifdef CONFIG_IP_PNP_DYNAMIC
  	else if (!strcmp(name, "both")) {
  		return 1;
  	}
  #endif
  	return 0;
  }
  
  static int __init ip_auto_config_setup(char *addrs)
  {
  	char *cp, *ip, *dp;
  	int num = 0;
  
  	ic_set_manually = 1;
  	if (!strcmp(addrs, "off")) {
  		ic_enable = 0;
  		return 1;
  	}
  	if (ic_proto_name(addrs))
  		return 1;
  
  	/* Parse the whole string */
  	ip = addrs;
  	while (ip && *ip) {
  		if ((cp = strchr(ip, ':')))
  			*cp++ = '\0';
  		if (strlen(ip) > 0) {
  			DBG(("IP-Config: Parameter #%d: `%s'\n", num, ip));
  			switch (num) {
  			case 0:
  				if ((ic_myaddr = in_aton(ip)) == INADDR_ANY)
  					ic_myaddr = INADDR_NONE;
  				break;
  			case 1:
  				if ((ic_servaddr = in_aton(ip)) == INADDR_ANY)
  					ic_servaddr = INADDR_NONE;
  				break;
  			case 2:
  				if ((ic_gateway = in_aton(ip)) == INADDR_ANY)
  					ic_gateway = INADDR_NONE;
  				break;
  			case 3:
  				if ((ic_netmask = in_aton(ip)) == INADDR_ANY)
  					ic_netmask = INADDR_NONE;
  				break;
  			case 4:
  				if ((dp = strchr(ip, '.'))) {
  					*dp++ = '\0';
  					strncpy(system_utsname.domainname, dp, __NEW_UTS_LEN);
  					system_utsname.domainname[__NEW_UTS_LEN] = '\0';
  				}
  				strncpy(system_utsname.nodename, ip, __NEW_UTS_LEN);
  				system_utsname.nodename[__NEW_UTS_LEN] = '\0';
  				ic_host_name_set = 1;
  				break;
  			case 5:
  				strncpy(user_dev_name, ip, IFNAMSIZ);
  				user_dev_name[IFNAMSIZ-1] = '\0';
  				break;
  			case 6:
  				ic_proto_name(ip);
  				break;
  			}
  		}
  		ip = cp;
  		num++;
  	}
  
  	return 1;
  }
  
  static int __init nfsaddrs_config_setup(char *addrs)
  {
  	return ip_auto_config_setup(addrs);
  }
  
  __setup("ip=", ip_auto_config_setup);
  __setup("nfsaddrs=", nfsaddrs_config_setup);
  