ipconfig.c

linux 内核源代码

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 =	__constant_htons(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;

#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);
	}

	*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 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 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;
	int hh_len = LL_RESERVED_SPACE(dev);
	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_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 */
	}
	b->hlen = dev->addr_len;
	b->your_ip = NONE;
	b->server_ip = NONE;
	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 (dev->nd_net != &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;
	}

	/* 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 %u.%u.%u.%u",
				       NIPQUAD(ic_myaddr));
				printk(" by server %u.%u.%u.%u\n",
				       NIPQUAD(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);