/*
 *  Automatic Configuration of IP -- use DHCP, BOOTP, 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
 *
 *  DHCP support added.  To users this looks like a whole separate
 *  protocol, but we know it's just a bag on the side of BOOTP.
 *              -- Chip Salzenberg <chip@valinux.com>, May 2000
 *
 *  Ported DHCP support from 2.2.16 to 2.4.0-test4
 *              -- Eric Biederman <ebiederman@lnxi.com>, 30 Aug 2000
 *
 *  Merged changes from 2.2.19 into 2.4.3
 *              -- Eric Biederman <ebiederman@lnxi.com>, 22 April Aug 2001
 *
 *  Multiple Nameservers in /proc/net/pnp
 *              --  Josef Siemes <jsiemes@web.de>, Aug 2002
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/jiffies.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/inetdevice.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 <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/major.h>
#include <linux/root_dev.h>
#include <linux/delay.h>
#include <linux/nfs_fs.h>
#include <net/net_namespace.h>
#include <net/arp.h>
#include <net/ip.h>
#include <net/ipconfig.h>
#include <net/route.h>

#include <asm/uaccess.h>
#include <net/checksum.h>
#include <asm/processor.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

#if defined(CONFIG_IP_PNP_DHCP)
#define IPCONFIG_DHCP
#endif
#if defined(CONFIG_IP_PNP_BOOTP) || defined(CONFIG_IP_PNP_DHCP)
#define IPCONFIG_BOOTP
#endif
#if defined(CONFIG_IP_PNP_RARP)
#define IPCONFIG_RARP
#endif
#if defined(IPCONFIG_BOOTP) || defined(IPCONFIG_RARP)
#define IPCONFIG_DYNAMIC
#endif

/* Define the friendly delay before and after opening net devices */
#define CONF_PRE_OPEN           500     /* Before opening: 1/2 second */
#define CONF_POST_OPEN          1       /* After opening: 1 second */

/* Define the timeout for waiting for a DHCP/BOOTP/RARP reply */
#define CONF_OPEN_RETRIES       2       /* (Re)open devices twice */
#define CONF_SEND_RETRIES       6       /* Send six requests per open */
#define CONF_INTER_TIMEOUT      (HZ/2)  /* Inter-device timeout: 1/2 second */
#define CONF_BASE_TIMEOUT       (HZ*2)  /* Initial timeout: 2 seconds */
#define CONF_TIMEOUT_RANDOM     (HZ)    /* Maximum amount of randomization */
#define CONF_TIMEOUT_MULT       *7/4    /* Rate of timeout growth */
#define CONF_TIMEOUT_MAX        (HZ*30) /* Maximum allowed timeout */
#define CONF_NAMESERVERS_MAX   3       /* Maximum number of nameservers
                                           - '3' from resolv.h */

#define NONE cpu_to_be32(INADDR_NONE)
#define ANY cpu_to_be32(INADDR_ANY)

/*
 * Public IP configuration
 */

/* This is used by platforms which might be able to set the ipconfig
 * variables using firmware environment vars.  If this is set, it will
 * ignore such firmware variables.
 */
int ic_set_manually __initdata = 0;             /* IPconfig parameters set manually */

static int ic_enable __initdata = 0;            /* IP config enabled? */

/* Protocol choice */
int ic_proto_enabled __initdata = 0
#ifdef IPCONFIG_BOOTP
                        | IC_BOOTP
#endif
#ifdef CONFIG_IP_PNP_DHCP
                        | IC_USE_DHCP
#endif
#ifdef IPCONFIG_RARP
                        | IC_RARP
#endif
                        ;

static int ic_host_name_set __initdata = 0;     /* Host name set by us? */

__be32 ic_myaddr = NONE;                /* My IP address */
static __be32 ic_netmask = NONE;        /* Netmask for local subnet */
__be32 ic_gateway = NONE;       /* Gateway IP address */

__be32 ic_servaddr = NONE;      /* Boot server IP address */

__be32 root_server_addr = NONE; /* Address of NFS server */
u8 root_server_path[256] = { 0, };      /* Path to mount as root */

u32 ic_dev_xid;         /* Device under configuration */

/* vendor class identifier */
static char vendor_class_identifier[253] __initdata;

/* Persistent data: */

static int ic_proto_used;                       /* Protocol used, if any */
static __be32 ic_nameservers[CONF_NAMESERVERS_MAX]; /* DNS Server IP addresses */
static u8 ic_domain[64];                /* DNS (not NIS) domain name */

/*
 * Private state.
 */

/* Name of user-selected boot device */
static char user_dev_name[IFNAMSIZ] __initdata = { 0, };

/* Protocols supported by available interfaces */
static int ic_proto_have_if __initdata = 0;

#ifdef IPCONFIG_DYNAMIC
static DEFINE_SPINLOCK(ic_recv_lock);
static volatile int ic_got_reply __initdata = 0;    /* Proto(s) that replied */
#endif
#ifdef IPCONFIG_DHCP
static int ic_dhcp_msgtype __initdata = 0;      /* DHCP msg type received */
#endif


/*
 *      Network devices
 */

struct ic_device {
        struct ic_device *next;
        struct net_device *dev;
        unsigned short flags;
        short able;
        __be32 xid;
};

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_lock();

        /* bring loopback device up first */
        for_each_netdev(&init_net, dev) {
                if (!(dev->flags & IFF_LOOPBACK))
                        continue;
                if (dev_change_flags(dev, dev->flags | IFF_UP) < 0)
                        printk(KERN_ERR "IP-Config: Failed to open %s\n", dev->name);
        }

        for_each_netdev(&init_net, dev) {
                if (dev->flags & IFF_LOOPBACK)
                        continue;
                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 "DHCP/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))) {
                                rtnl_unlock();
                                return -1;
                        }
                        d->dev = dev;
                        *last = d;
                        last = &d->next;
                        d->flags = oflags;
                        d->able = able;
                        if (able & IC_BOOTP)
                                get_random_bytes(&d->xid, sizeof(__be32));
                        else
                                d->xid = 0;
                        ic_proto_have_if |= able;
                        DBG(("IP-Config: %s UP (able=%d, xid=%08x)\n",
                                dev->name, able, d->xid));
                }
        }
        rtnl_unlock();

        *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_lock();
        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_unlock();
}

/*
 *      Interface to various network functions.
 */

static inline void
set_sockaddr(struct sockaddr_in *sin, __be32 addr, __be16 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(&init_net, cmd, (struct ifreq __user *) 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(&init_net, cmd, (void __user *) 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 != 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)
                sprintf(init_utsname()->nodename, "%pI4", &ic_myaddr);

        if (root_server_addr == NONE)
                root_server_addr = ic_servaddr;

        if (ic_netmask == 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 %pI4\n",
                                &ic_myaddr);
                        return -1;
                }
                printk("IP-Config: Guessing netmask %pI4\n", &ic_netmask);
        }

        return 0;
}

/*
 *      RARP support.
 */

#ifdef IPCONFIG_RARP

static int ic_rarp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev);

static struct packet_type rarp_packet_type __initdata = {
        .type = cpu_to_be16(ETH_P_RARP),
        .func = ic_rarp_recv,
};

static inline void __init ic_rarp_init(void)
{
        dev_add_pack(&rarp_packet_type);
}

static inline void __init 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 net_device *orig_dev)
{
        struct arphdr *rarp;
        unsigned char *rarp_ptr;
        __be32 sip, tip;
        unsigned char *sha, *tha;               /* s for "source", t for "target" */
        struct ic_device *d;

        if (!net_eq(dev_net(dev), &init_net))
                goto drop;

        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
                return NET_RX_DROP;

        if (!pskb_may_pull(skb, sizeof(struct arphdr)))
                goto drop;

        /* Basic sanity checks can be done without the lock.  */
        rarp = (struct arphdr *)skb_transport_header(skb);

        /* 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;

        if (!pskb_may_pull(skb, arp_hdr_len(dev)))
                goto drop;

        /* OK, it is all there and looks valid, process... */
        rarp = (struct arphdr *)skb_transport_header(skb);
        rarp_ptr = (unsigned char *) (rarp + 1);

        /* One reply at a time, please. */
        spin_lock(&ic_recv_lock);

        /* If we already have a reply, just drop the packet */
        if (ic_got_reply)
                goto drop_unlock;

        /* Find the ic_device that the packet arrived on */
        d = ic_first_dev;
        while (d && d->dev != dev)
                d = d->next;
        if (!d)
                goto drop_unlock;       /* should never happen */

        /* 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_unlock;

        /* Discard packets which are not from specified server. */
        if (ic_servaddr != NONE && ic_servaddr != sip)
                goto drop_unlock;

        /* We have a winner! */
        ic_dev = dev;
        if (ic_myaddr == NONE)
                ic_myaddr = tip;
        ic_servaddr = sip;
        ic_got_reply = IC_RARP;

drop_unlock:
        /* Show's over.  Nothing to see here.  */
        spin_unlock(&ic_recv_lock);

drop:
        /* Throw the packet out. */
        kfree_skb(skb);
        return 0;
}


/*
 *  Send RARP request packet over a single interface.
 */
static void __init ic_rarp_send_if(struct ic_device *d)
{
        struct net_device *dev = d->dev;
        arp_send(ARPOP_RREQUEST, ETH_P_RARP, 0, dev, 0, NULL,
                 dev->dev_addr, dev->dev_addr);
}
#endif

/*
 *      DHCP/BOOTP support.
 */

#ifdef IPCONFIG_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 */
        __be32 xid;             /* Transaction ID */
        __be16 secs;            /* Seconds since we started */
        __be16 flags;           /* Just what it says */
        __be32 client_ip;               /* Client's IP address if known */
        __be32 your_ip;         /* Assigned IP address */
        __be32 server_ip;               /* (Next, e.g. NFS) Server's IP address */
        __be32 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 exten[312];          /* DHCP options / BOOTP vendor extensions */
};

/* packet ops */
#define BOOTP_REQUEST   1
#define BOOTP_REPLY     2

/* DHCP message types */
#define DHCPDISCOVER    1
#define DHCPOFFER       2
#define DHCPREQUEST     3
#define DHCPDECLINE     4
#define DHCPACK         5
#define DHCPNAK         6
#define DHCPRELEASE     7
#define DHCPINFORM      8

static int ic_bootp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev);

static struct packet_type bootp_packet_type __initdata = {
        .type = cpu_to_be16(ETH_P_IP),
        .func = ic_bootp_recv,
};


/*
 *  Initialize DHCP/BOOTP extension fields in the request.
 */

static const u8 ic_bootp_cookie[4] = { 99, 130, 83, 99 };

#ifdef IPCONFIG_DHCP

static void __init
ic_dhcp_init_options(u8 *options)
{
        u8 mt = ((ic_servaddr == NONE)
                 ? DHCPDISCOVER : DHCPREQUEST);
        u8 *e = options;
        int len;

#ifdef IPCONFIG_DEBUG
        printk("DHCP: Sending message type %d\n", mt);
#endif

        memcpy(e, ic_bootp_cookie, 4);  /* RFC1048 Magic Cookie */
        e += 4;

        *e++ = 53;              /* DHCP message type */
        *e++ = 1;
        *e++ = mt;

        if (mt == DHCPREQUEST) {
                *e++ = 54;      /* Server ID (IP address) */
                *e++ = 4;
                memcpy(e, &ic_servaddr, 4);
                e += 4;

                *e++ = 50;      /* Requested IP address */
                *e++ = 4;
                memcpy(e, &ic_myaddr, 4);
                e += 4;
        }

        /* always? */
        {
                static const u8 ic_req_params[] = {
                        1,      /* Subnet mask */
                        3,      /* Default gateway */
                        6,      /* DNS server */
                        12,     /* Host name */
                        15,     /* Domain name */
                        17,     /* Boot path */
                        40,     /* NIS domain name */
                };

                *e++ = 55;      /* Parameter request list */
                *e++ = sizeof(ic_req_params);
                memcpy(e, ic_req_params, sizeof(ic_req_params));
                e += sizeof(ic_req_params);

                if (*vendor_class_identifier) {
                        printk(KERN_INFO "DHCP: sending class identifier \"%s\"\n",
                               vendor_class_identifier);
                        *e++ = 60;      /* Class-identifier */
                        len = strlen(vendor_class_identifier);
                        *e++ = len;
                        memcpy(e, vendor_class_identifier, len);
                        e += len;
                }
        }

        *e++ = 255;     /* End of the list */
}

#endif /* IPCONFIG_DHCP */

static void __init ic_bootp_init_ext(u8 *e)
{
        memcpy(e, ic_bootp_cookie, 4);  /* RFC1048 Magic Cookie */
        e += 4;
        *e++ = 1;               /* Subnet mask request */
        *e++ = 4;
        e += 4;
        *e++ = 3;               /* Default gateway request */
        *e++ = 4;
        e += 4;
        *e++ = 5;               /* Name server request */
        *e++ = 8;
        e += 8;
        *e++ = 12;              /* Host name request */
        *e++ = 32;
        e += 32;
        *e++ = 40;              /* NIS Domain name request */
        *e++ = 32;
        e += 32;
        *e++ = 17;              /* Boot path */
        *e++ = 40;
        e += 40;

        *e++ = 57;              /* set extension buffer size for reply */
        *e++ = 2;
        *e++ = 1;               /* 128+236+8+20+14, see dhcpd sources */
        *e++ = 150;

        *e++ = 255;             /* End of the list */
}


/*
 *  Initialize the DHCP/BOOTP mechanism.
 */
static inline void __init ic_bootp_init(void)
{
        int i;

        for (i = 0; i < CONF_NAMESERVERS_MAX; i++)
                ic_nameservers[i] = NONE;

        dev_add_pack(&bootp_packet_type);
}


/*
 *  DHCP/BOOTP cleanup.
 */
static inline void __init ic_bootp_cleanup(void)
{
        dev_remove_pack(&bootp_packet_type);
}


/*
 *  Send DHCP/BOOTP request to single interface.
 */
static void __init ic_bootp_send_if(struct ic_device *d, unsigned long jiffies_diff)
{
        struct net_device *dev = d->dev;
        struct sk_buff *skb;
        struct bootp_pkt *b;
        struct iphdr *h;

        /* Allocate packet */
        skb = alloc_skb(sizeof(struct bootp_pkt) + LL_ALLOCATED_SPACE(dev) + 15,
                        GFP_KERNEL);
        if (!skb)
                return;
        skb_reserve(skb, LL_RESERVED_SPACE(dev));
        b = (struct bootp_pkt *) skb_put(skb, sizeof(struct bootp_pkt));
        memset(b, 0, sizeof(struct bootp_pkt));

        /* Construct IP header */
        skb_reset_network_header(skb);
        h = ip_hdr(skb);
        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 = htonl(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 DHCP/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 if (dev->type == ARPHRD_FDDI)
                b->htype = ARPHRD_ETHER;
        else {
                printk("Unknown ARP type 0x%04x for device %s\n", dev->type, dev->name);
                b->htype = dev->type; /* can cause undefined behavior */
        }

        /* server_ip and your_ip address are both already zero per RFC2131 */
        b->hlen = dev->addr_len;
        memcpy(b->hw_addr, dev->dev_addr, dev->addr_len);
        b->secs = htons(jiffies_diff / HZ);
        b->xid = d->xid;

        /* add DHCP options or BOOTP extensions */
#ifdef IPCONFIG_DHCP
        if (ic_proto_enabled & IC_USE_DHCP)
                ic_dhcp_init_options(b->exten);
        else
#endif
                ic_bootp_init_ext(b->exten);

        /* Chain packet down the line... */
        skb->dev = dev;
        skb->protocol = htons(ETH_P_IP);
        if (dev_hard_header(skb, dev, ntohs(skb->protocol),
                            dev->broadcast, dev->dev_addr, skb->len) < 0 ||
            dev_queue_xmit(skb) < 0)
                printk("E");
}


/*
 *  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;
        memcpy(dest, src, len);
        dest[len] = '\0';
        return 1;
}


/*
 *  Process BOOTP extensions.
 */
static void __init ic_do_bootp_ext(u8 *ext)
{
       u8 servers;
       int i;

#ifdef IPCONFIG_DEBUG
        u8 *c;

        printk("DHCP/BOOTP: Got extension %d:",*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 == NONE)
                                memcpy(&ic_netmask, ext+1, 4);
                        break;
                case 3:         /* Default gateway */
                        if (ic_gateway == NONE)
                                memcpy(&ic_gateway, ext+1, 4);
                        break;
                case 6:         /* DNS server */
                        servers= *ext/4;
                        if (servers > CONF_NAMESERVERS_MAX)
                                servers = CONF_NAMESERVERS_MAX;
                        for (i = 0; i < servers; i++) {
                                if (ic_nameservers[i] == NONE)
                                        memcpy(&ic_nameservers[i], ext+1+4*i, 4);
                        }
                        break;
                case 12:        /* Host name */
                        ic_bootp_string(utsname()->nodename, ext+1, *ext, __NEW_UTS_LEN);
                        ic_host_name_set = 1;
                        break;
                case 15:        /* Domain name (DNS) */
                        ic_bootp_string(ic_domain, ext+1, *ext, sizeof(ic_domain));
                        break;
                case 17:        /* Root path */
                        if (!root_server_path[0])
                                ic_bootp_string(root_server_path, ext+1, *ext, sizeof(root_server_path));
                        break;
                case 40:        /* NIS Domain name (_not_ DNS) */
                        ic_bootp_string(utsname()->domainname, ext+1, *ext, __NEW_UTS_LEN);
                        break;
        }
}


/*
 *  Receive BOOTP reply.
 */
static int __init ic_bootp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
        struct bootp_pkt *b;
        struct iphdr *h;
        struct ic_device *d;
        int len, ext_len;

        if (!net_eq(dev_net(dev), &init_net))
                goto drop;

        /* Perform verifications before taking the lock.  */
        if (skb->pkt_type == PACKET_OTHERHOST)
                goto drop;

        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
                return NET_RX_DROP;

        if (!pskb_may_pull(skb,
                           sizeof(struct iphdr) +
                           sizeof(struct udphdr)))
                goto drop;

        b = (struct bootp_pkt *)skb_network_header(skb);
        h = &b->iph;

        if (h->ihl != 5 || h->version != 4 || h->protocol != IPPROTO_UDP)
                goto drop;

        /* Fragments are not supported */
        if (h->frag_off & htons(IP_OFFSET | IP_MF)) {
                if (net_ratelimit())
                        printk(KERN_ERR "DHCP/BOOTP: Ignoring fragmented "
                               "reply.\n");
                goto drop;
        }

        if (skb->len < ntohs(h->tot_len))
                goto drop;

        if (ip_fast_csum((char *) h, h->ihl))
                goto drop;

        if (b->udph.source != htons(67) || b->udph.dest != htons(68))
                goto drop;

        if (ntohs(h->tot_len) < ntohs(b->udph.len) + sizeof(struct iphdr))
                goto drop;

        len = ntohs(b->udph.len) - sizeof(struct udphdr);
        ext_len = len - (sizeof(*b) -
                         sizeof(struct iphdr) -
                         sizeof(struct udphdr) -
                         sizeof(b->exten));
        if (ext_len < 0)
                goto drop;

        /* Ok the front looks good, make sure we can get at the rest.  */
        if (!pskb_may_pull(skb, skb->len))
                goto drop;

        b = (struct bootp_pkt *)skb_network_header(skb);
        h = &b->iph;

        /* One reply at a time, please. */
        spin_lock(&ic_recv_lock);

        /* If we already have a reply, just drop the packet */
        if (ic_got_reply)
                goto drop_unlock;

        /* Find the ic_device that the packet arrived on */
        d = ic_first_dev;
        while (d && d->dev != dev)
                d = d->next;
        if (!d)
                goto drop_unlock;  /* should never happen */

        /* Is it a reply to our BOOTP request? */
        if (b->op != BOOTP_REPLY ||
            b->xid != d->xid) {
                if (net_ratelimit())
                        printk(KERN_ERR "DHCP/BOOTP: Reply not for us, "
                               "op[%x] xid[%x]\n",
                               b->op, b->xid);
                goto drop_unlock;
        }

        /* Is it a reply for the device we are configuring? */
        if (b->xid != ic_dev_xid) {
                if (net_ratelimit())
                        printk(KERN_ERR "DHCP/BOOTP: Ignoring delayed packet \n");
                goto drop_unlock;
        }

        /* Parse extensions */
        if (ext_len >= 4 &&
            !memcmp(b->exten, ic_bootp_cookie, 4)) { /* Check magic cookie */
                u8 *end = (u8 *) b + ntohs(b->iph.tot_len);
                u8 *ext;

#ifdef IPCONFIG_DHCP
                if (ic_proto_enabled & IC_USE_DHCP) {
                        __be32 server_id = NONE;
                        int mt = 0;

                        ext = &b->exten[4];
                        while (ext < end && *ext != 0xff) {
                                u8 *opt = ext++;
                                if (*opt == 0)  /* Padding */
                                        continue;
                                ext += *ext + 1;
                                if (ext >= end)
                                        break;
                                switch (*opt) {
                                case 53:        /* Message type */
                                        if (opt[1])
                                                mt = opt[2];
                                        break;
                                case 54:        /* Server ID (IP address) */
                                        if (opt[1] >= 4)
                                                memcpy(&server_id, opt + 2, 4);
                                        break;
                                }
                        }

#ifdef IPCONFIG_DEBUG
                        printk("DHCP: Got message type %d\n", mt);
#endif

                        switch (mt) {
                        case DHCPOFFER:
                                /* While in the process of accepting one offer,
                                 * ignore all others.
                                 */
                                if (ic_myaddr != NONE)
                                        goto drop_unlock;

                                /* Let's accept that offer. */
                                ic_myaddr = b->your_ip;
                                ic_servaddr = server_id;
#ifdef IPCONFIG_DEBUG
                                printk("DHCP: Offered address %pI4 by server %pI4\n",
                                       &ic_myaddr, &ic_servaddr);
#endif
                                /* The DHCP indicated server address takes
                                 * precedence over the bootp header one if
                                 * they are different.
                                 */
                                if ((server_id != NONE) &&
                                    (b->server_ip != server_id))
                                        b->server_ip = ic_servaddr;

                                break;

                        case DHCPACK:
                                if (memcmp(dev->dev_addr, b->hw_addr, dev->addr_len) != 0)
                                        goto drop_unlock;

                                /* Yeah! */
                                break;

                        default:
                                /* Urque.  Forget it*/
                                ic_myaddr = NONE;
                                ic_servaddr = NONE;
                                goto drop_unlock;
                        }

                        ic_dhcp_msgtype = mt;

                }
#endif /* IPCONFIG_DHCP */

                ext = &b->exten[4];
                while (ext < end && *ext != 0xff) {
                        u8 *opt = ext++;
                        if (*opt == 0)  /* Padding */
                                continue;
                        ext += *ext + 1;
                        if (ext < end)
                                ic_do_bootp_ext(opt);
                }
        }

        /* We have a winner! */
        ic_dev = dev;
        ic_myaddr = b->your_ip;
        ic_servaddr = b->server_ip;
        if (ic_gateway == NONE && b->relay_ip)
                ic_gateway = b->relay_ip;
        if (ic_nameservers[0] == NONE)
                ic_nameservers[0] = ic_servaddr;
        ic_got_reply = IC_BOOTP;

drop_unlock:
        /* Show's over.  Nothing to see here.  */
        spin_unlock(&ic_recv_lock);

drop:
        /* Throw the packet out. */
        kfree_skb(skb);

        return 0;
}


#endif


/*
 *      Dynamic IP configuration -- DHCP, BOOTP, RARP.
 */

#ifdef IPCONFIG_DYNAMIC

static int __init ic_dynamic(void)
{
        int retries;
        struct ic_device *d;
        unsigned long start_jiffies, timeout, jiff;
        int do_bootp = ic_proto_have_if & IC_BOOTP;
        int do_rarp = ic_proto_have_if & IC_RARP;

        /*
         * If none of DHCP/BOOTP/RARP was selected, return with an error.
         * This routine gets only called when some pieces of information
         * are missing, and without DHCP/BOOTP/RARP we are unable to get it.
         */
        if (!ic_proto_enabled) {
                printk(KERN_ERR "IP-Config: Incomplete network configuration information.\n");
                return -1;
        }

#ifdef IPCONFIG_BOOTP
        if ((ic_proto_enabled ^ ic_proto_have_if) & IC_BOOTP)
                printk(KERN_ERR "DHCP/BOOTP: No suitable device found.\n");
#endif
#ifdef IPCONFIG_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 protocols
         */
#ifdef IPCONFIG_BOOTP
        if (do_bootp)
                ic_bootp_init();
#endif
#ifdef IPCONFIG_RARP
        if (do_rarp)
                ic_rarp_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
                ? ((ic_proto_enabled & IC_USE_DHCP) ? "DHCP" : "BOOTP") : "",
               (do_bootp && do_rarp) ? " and " : "",
               do_rarp ? "RARP" : "");

        start_jiffies = jiffies;
        d = ic_first_dev;
        retries = CONF_SEND_RETRIES;
        get_random_bytes(&timeout, sizeof(timeout));
        timeout = CONF_BASE_TIMEOUT + (timeout % (unsigned) CONF_TIMEOUT_RANDOM);
        for (;;) {
                /* Track the device we are configuring */
                ic_dev_xid = d->xid;

#ifdef IPCONFIG_BOOTP
                if (do_bootp && (d->able & IC_BOOTP))
                        ic_bootp_send_if(d, jiffies - start_jiffies);
#endif
#ifdef IPCONFIG_RARP
                if (do_rarp && (d->able & IC_RARP))
                        ic_rarp_send_if(d);
#endif

                jiff = jiffies + (d->next ? CONF_INTER_TIMEOUT : timeout);
                while (time_before(jiffies, jiff) && !ic_got_reply)
                        schedule_timeout_uninterruptible(1);
#ifdef IPCONFIG_DHCP
                /* DHCP isn't done until we get a DHCPACK. */
                if ((ic_got_reply & IC_BOOTP)
                    && (ic_proto_enabled & IC_USE_DHCP)
                    && ic_dhcp_msgtype != DHCPACK)
                {
                        ic_got_reply = 0;
                        printk(",");
                        continue;
                }
#endif /* IPCONFIG_DHCP */

                if (ic_got_reply) {
                        printk(" OK\n");
                        break;
                }

                if ((d = d->next))
                        continue;

                if (! --retries) {
                        printk(" timed out!\n");
                        break;
                }

                d = ic_first_dev;

                timeout = timeout CONF_TIMEOUT_MULT;
                if (timeout > CONF_TIMEOUT_MAX)
                        timeout = CONF_TIMEOUT_MAX;

                printk(".");
        }

#ifdef IPCONFIG_BOOTP
        if (do_bootp)
                ic_bootp_cleanup();
#endif
#ifdef IPCONFIG_RARP
        if (do_rarp)
                ic_rarp_cleanup();
#endif

        if (!ic_got_reply) {
                ic_myaddr = NONE;
                return -1;
        }

        printk("IP-Config: Got %s answer from %pI4, ",
                ((ic_got_reply & IC_RARP) ? "RARP"
                 : (ic_proto_enabled & IC_USE_DHCP) ? "DHCP" : "BOOTP"),
                &ic_servaddr);
        printk("my address is %pI4\n", &ic_myaddr);

        return 0;
}

#endif /* IPCONFIG_DYNAMIC */

#ifdef CONFIG_PROC_FS

static int pnp_seq_show(struct seq_file *seq, void *v)
{
        int i;

        if (ic_proto_used & IC_PROTO)
                seq_printf(seq, "#PROTO: %s\n",
                           (ic_proto_used & IC_RARP) ? "RARP"
                           : (ic_proto_used & IC_USE_DHCP) ? "DHCP" : "BOOTP");
        else
                seq_puts(seq, "#MANUAL\n");

        if (ic_domain[0])
                seq_printf(seq,
                           "domain %s\n", ic_domain);
        for (i = 0; i < CONF_NAMESERVERS_MAX; i++) {
                if (ic_nameservers[i] != NONE)
                        seq_printf(seq, "nameserver %pI4\n",
                                   &ic_nameservers[i]);
        }
        if (ic_servaddr != NONE)
                seq_printf(seq, "bootserver %pI4\n",
                           &ic_servaddr);
        return 0;
}

static int pnp_seq_open(struct inode *indoe, struct file *file)
{
        return single_open(file, pnp_seq_show, NULL);
}

static const struct file_operations pnp_seq_fops = {
        .owner          = THIS_MODULE,
        .open           = pnp_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};
#endif /* CONFIG_PROC_FS */

/*
 *  Extract IP address from the parameter string if needed. Note that we
 *  need to have root_server_addr set _before_ IPConfig gets called as it
 *  can override it.
 */
__be32 __init root_nfs_parse_addr(char *name)
{
        __be32 addr;
        int octets = 0;
        char *cp, *cq;

        cp = cq = name;
        while (octets < 4) {
                while (*cp >= '0' && *cp <= '9')
                        cp++;
                if (cp == cq || cp - cq > 3)
                        break;
                if (*cp == '.' || octets == 3)
                        octets++;
                if (octets < 4)
                        cp++;
                cq = cp;
        }
        if (octets == 4 && (*cp == ':' || *cp == '\0')) {
                if (*cp == ':')
                        *cp++ = '\0';
                addr = in_aton(name);
                memmove(name, cp, strlen(cp) + 1);
        } else
                addr = NONE;

        return addr;
}

/*
 *      IP Autoconfig dispatcher.
 */

static int __init ip_auto_config(void)
{
        __be32 addr;
#ifdef IPCONFIG_DYNAMIC
        int retries = CONF_OPEN_RETRIES;
#endif

#ifdef CONFIG_PROC_FS
        proc_net_fops_create(&init_net, "pnp", S_IRUGO, &pnp_seq_fops);
#endif /* CONFIG_PROC_FS */

        if (!ic_enable)
                return 0;

        DBG(("IP-Config: Entered.\n"));
#ifdef IPCONFIG_DYNAMIC
 try_try_again:
#endif
        /* Give hardware a chance to settle */
        msleep(CONF_PRE_OPEN);

        /* Setup all network devices */
        if (ic_open_devs() < 0)
                return -1;

        /* Give drivers a chance to settle */
        ssleep(CONF_POST_OPEN);

        /*
         * 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 == NONE ||
#ifdef CONFIG_ROOT_NFS
            (root_server_addr == NONE
             && ic_servaddr == NONE
             && ROOT_DEV == Root_NFS) ||
#endif
            ic_first_dev->next) {
#ifdef IPCONFIG_DYNAMIC
                if (ic_dynamic() < 0) {
                        ic_close_devs();

                        /*
                         * I don't know why, but sometimes the
                         * eepro100 driver (at least) gets upset and
                         * doesn't work the first time it's opened.
                         * But then if you close it and reopen it, it
                         * works just fine.  So we need to try that at
                         * least once before giving up.
                         *
                         * Also, if the root will be NFS-mounted, we
                         * have nowhere to go if DHCP fails.  So we
                         * just have to keep trying forever.
                         *
                         *                              -- Chip
                         */
#ifdef CONFIG_ROOT_NFS
                        if (ROOT_DEV ==  Root_NFS) {
                                printk(KERN_ERR
                                        "IP-Config: Retrying forever (NFS root)...\n");
                                goto try_try_again;
                        }
#endif

                        if (--retries) {
                                printk(KERN_ERR
                                       "IP-Config: Reopening network devices...\n");
                                goto try_try_again;
                        }

                        /* Oh, well.  At least we tried. */
                        printk(KERN_ERR "IP-Config: Auto-configuration of network failed.\n");
                        return -1;
                }
#else /* !DYNAMIC */
                printk(KERN_ERR "IP-Config: Incomplete network configuration information.\n");
                ic_close_devs();
                return -1;
#endif /* IPCONFIG_DYNAMIC */
        } else {
                /* Device selected manually or only one device -> use it */
                ic_dev = ic_first_dev->dev;
        }

        addr = root_nfs_parse_addr(root_server_path);
        if (root_server_addr == NONE)
                root_server_addr = addr;

        /*
         * 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;

        /*
         * Record which protocol was actually used.
         */
#ifdef IPCONFIG_DYNAMIC
        ic_proto_used = ic_got_reply | (ic_proto_enabled & IC_USE_DHCP);
#endif

#ifndef IPCONFIG_SILENT
        /*
         * Clue in the operator.
         */
        printk("IP-Config: Complete:");
        printk("\n     device=%s", ic_dev->name);
        printk(", addr=%pI4", &ic_myaddr);
        printk(", mask=%pI4", &ic_netmask);
        printk(", gw=%pI4", &ic_gateway);
        printk(",\n     host=%s, domain=%s, nis-domain=%s",
               utsname()->nodename, ic_domain, utsname()->domainname);
        printk(",\n     bootserver=%pI4", &ic_servaddr);
        printk(", rootserver=%pI4", &root_server_addr);
        printk(", rootpath=%s", root_server_path);
        printk("\n");
#endif /* !SILENT */

        return 0;
}

late_initcall(ip_auto_config);


/*
 *  Decode any IP configuration options in the "ip=" or "nfsaddrs=" kernel
 *  command line parameter.  See Documentation/filesystems/nfsroot.txt.
 */
static int __init ic_proto_name(char *name)
{
        if (!strcmp(name, "on") || !strcmp(name, "any")) {
                return 1;
        }
        if (!strcmp(name, "off") || !strcmp(name, "none")) {
                return 0;
        }
#ifdef CONFIG_IP_PNP_DHCP
        else if (!strcmp(name, "dhcp")) {
                ic_proto_enabled &= ~IC_RARP;
                return 1;
        }
#endif
#ifdef CONFIG_IP_PNP_BOOTP
        else if (!strcmp(name, "bootp")) {
                ic_proto_enabled &= ~(IC_RARP | IC_USE_DHCP);
                return 1;
        }
#endif
#ifdef CONFIG_IP_PNP_RARP
        else if (!strcmp(name, "rarp")) {
                ic_proto_enabled &= ~(IC_BOOTP | IC_USE_DHCP);
                return 1;
        }
#endif
#ifdef IPCONFIG_DYNAMIC
        else if (!strcmp(name, "both")) {
                ic_proto_enabled &= ~IC_USE_DHCP; /* backward compat :-( */
                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;
        ic_enable = 1;

        /*
         * If any dhcp, bootp etc options are set, leave autoconfig on
         * and skip the below static IP processing.
         */
        if (ic_proto_name(addrs))
                return 1;

        /* If no static IP is given, turn off autoconfig and bail.  */
        if (*addrs == 0 ||
            strcmp(addrs, "off") == 0 ||
            strcmp(addrs, "none") == 0) {
                ic_enable = 0;
                return 1;
        }

        /* Parse string for static IP assignment.  */
        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)) == ANY)
                                        ic_myaddr = NONE;
                                break;
                        case 1:
                                if ((ic_servaddr = in_aton(ip)) == ANY)
                                        ic_servaddr = NONE;
                                break;
                        case 2:
                                if ((ic_gateway = in_aton(ip)) == ANY)
                                        ic_gateway = NONE;
                                break;
                        case 3:
                                if ((ic_netmask = in_aton(ip)) == ANY)
                                        ic_netmask = NONE;
                                break;
                        case 4:
                                if ((dp = strchr(ip, '.'))) {
                                        *dp++ = '\0';
                                        strlcpy(utsname()->domainname, dp,
                                                sizeof(utsname()->domainname));
                                }
                                strlcpy(utsname()->nodename, ip,
                                        sizeof(utsname()->nodename));
                                ic_host_name_set = 1;
                                break;
                        case 5:
                                strlcpy(user_dev_name, ip, sizeof(user_dev_name));
                                break;
                        case 6:
                                if (ic_proto_name(ip) == 0 &&
                                    ic_myaddr == NONE) {
                                        ic_enable = 0;
                                }
                                break;
                        }
                }
                ip = cp;
                num++;
        }

        return 1;
}

static int __init nfsaddrs_config_setup(char *addrs)
{
        return ip_auto_config_setup(addrs);
}

static int __init vendor_class_identifier_setup(char *addrs)
{
        if (strlcpy(vendor_class_identifier, addrs,
                    sizeof(vendor_class_identifier))
            >= sizeof(vendor_class_identifier))
                printk(KERN_WARNING "DHCP: vendorclass too long, truncated to \"%s\"",
                       vendor_class_identifier);
        return 1;
}

__setup("ip=", ip_auto_config_setup);
__setup("nfsaddrs=", nfsaddrs_config_setup);
__setup("dhcpclass=", vendor_class_identifier_setup);