net.c

/*
 *	Copied from Linux Monitor (LiMon) - Networking.
 *
 *	Copyright 1994 - 2000 Neil Russell.
 *	(See License)
 *	Copyright 2000 Roland Borde
 *	Copyright 2000 Paolo Scaffardi
 *	Copyright 2000-2002 Wolfgang Denk, wd@denx.de
 */

/*
 * General Desription:
 *
 * The user interface supports commands for BOOTP, RARP, and TFTP.
 * Also, we support ARP internally. Depending on available data,
 * these interact as follows:
 *
 * BOOTP:
 *
 *	Prerequisites:	- own ethernet address
 *	We want:	- own IP address
 *			- TFTP server IP address
 *			- name of bootfile
 *	Next step:	ARP
 *
 * RARP:
 *
 *	Prerequisites:	- own ethernet address
 *	We want:	- own IP address
 *			- TFTP server IP address
 *	Next step:	ARP
 *
 * ARP:
 *
 *	Prerequisites:	- own ethernet address
 *			- own IP address
 *			- TFTP server IP address
 *	We want:	- TFTP server ethernet address
 *	Next step:	TFTP
 *
 * DHCP:
 *
 *     Prerequisites:	- own ethernet address
 *     We want:		- IP, Netmask, ServerIP, Gateway IP
 *			- bootfilename, lease time
 *     Next step:	- TFTP
 *
 * TFTP:
 *
 *	Prerequisites:	- own ethernet address
 *			- own IP address
 *			- TFTP server IP address
 *			- TFTP server ethernet address
 *			- name of bootfile (if unknown, we use a default name
 *			  derived from our own IP address)
 *	We want:	- load the boot file
 *	Next step:	none
 *
 * NFS:
 *
 *	Prerequisites:	- own ethernet address
 *			- own IP address
 *			- name of bootfile (if unknown, we use a default name
 *			  derived from our own IP address)
 *	We want:	- load the boot file
 *	Next step:	none
 *
 * SNTP:
 *
 *	Prerequisites:	- own ethernet address
 *			- own IP address
 *	We want:	- network time
 *	Next step:	none
 */


#include <common.h>
#include <watchdog.h>
#include <command.h>
#include <linux/compiler.h>
#include <net.h>
#include "bootp.h"
#include "tftp.h"
#ifdef CONFIG_CMD_RARP
#include "rarp.h"
#endif
#include "nfs.h"
#ifdef CONFIG_STATUS_LED
#include <status_led.h>
#include <miiphy.h>
#endif
#if defined(CONFIG_CMD_SNTP)
#include "sntp.h"
#endif
#include "cdp.h"
#if defined(CONFIG_CMD_DNS)
#include "dns.h"
#endif

DECLARE_GLOBAL_DATA_PTR;

#ifndef	CONFIG_ARP_TIMEOUT
/* Milliseconds before trying ARP again */
# define ARP_TIMEOUT		5000UL
#else
# define ARP_TIMEOUT		CONFIG_ARP_TIMEOUT
#endif


#ifndef	CONFIG_NET_RETRY_COUNT
# define ARP_TIMEOUT_COUNT	5	/* # of timeouts before giving up  */
#else
# define ARP_TIMEOUT_COUNT	CONFIG_NET_RETRY_COUNT
#endif

/** BOOTP EXTENTIONS **/

/* Our subnet mask (0=unknown) */
IPaddr_t	NetOurSubnetMask;
/* Our gateways IP address */
IPaddr_t	NetOurGatewayIP;
/* Our DNS IP address */
IPaddr_t	NetOurDNSIP;
#if defined(CONFIG_BOOTP_DNS2)
/* Our 2nd DNS IP address */
IPaddr_t	NetOurDNS2IP;
#endif
/* Our NIS domain */
char		NetOurNISDomain[32] = {0,};
/* Our hostname */
char		NetOurHostName[32] = {0,};
/* Our bootpath */
char		NetOurRootPath[64] = {0,};
/* Our bootfile size in blocks */
ushort		NetBootFileSize;

#ifdef CONFIG_MCAST_TFTP	/* Multicast TFTP */
IPaddr_t Mcast_addr;
#endif

/** END OF BOOTP EXTENTIONS **/

/* The actual transferred size of the bootfile (in bytes) */
ulong		NetBootFileXferSize;
/* Our ethernet address */
uchar		NetOurEther[6];
/* Boot server enet address */
uchar		NetServerEther[6];
/* Our IP addr (0 = unknown) */
IPaddr_t	NetOurIP;
/* Server IP addr (0 = unknown) */
IPaddr_t	NetServerIP;
/* Current receive packet */
uchar *NetRxPacket;
/* Current rx packet length */
int		NetRxPacketLen;
/* IP packet ID */
unsigned	NetIPID;
/* Ethernet bcast address */
uchar		NetBcastAddr[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
uchar		NetEtherNullAddr[6];
#ifdef CONFIG_API
void		(*push_packet)(void *, int len) = 0;
#endif
/* Network loop state */
int		NetState;
/* Tried all network devices */
int		NetRestartWrap;
/* Network loop restarted */
static int	NetRestarted;
/* At least one device configured */
static int	NetDevExists;

/* XXX in both little & big endian machines 0xFFFF == ntohs(-1) */
/* default is without VLAN */
ushort		NetOurVLAN = 0xFFFF;
/* ditto */
ushort		NetOurNativeVLAN = 0xFFFF;

/* Boot File name */
char		BootFile[128];

#if defined(CONFIG_CMD_PING)
/* the ip address to ping */
IPaddr_t	NetPingIP;

static void PingStart(void);
#endif

#if defined(CONFIG_CMD_SNTP)
/* NTP server IP address */
IPaddr_t	NetNtpServerIP;
/* offset time from UTC */
int		NetTimeOffset;
#endif

uchar PktBuf[(PKTBUFSRX+1) * PKTSIZE_ALIGN + PKTALIGN];

/* Receive packet */
uchar *NetRxPackets[PKTBUFSRX];

/* Current RX packet handler */
static rxhand_f *packetHandler;
#ifdef CONFIG_CMD_TFTPPUT
static rxhand_icmp_f *packet_icmp_handler;	/* Current ICMP rx handler */
#endif
/* Current timeout handler */
static thand_f *timeHandler;
/* Time base value */
static ulong	timeStart;
/* Current timeout value */
static ulong	timeDelta;
/* THE transmit packet */
uchar *NetTxPacket;

static int net_check_prereq(enum proto_t protocol);

static int NetTryCount;

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

IPaddr_t	NetArpWaitPacketIP;
IPaddr_t	NetArpWaitReplyIP;
/* MAC address of waiting packet's destination */
uchar	       *NetArpWaitPacketMAC;
/* THE transmit packet */
uchar	       *NetArpWaitTxPacket;
int		NetArpWaitTxPacketSize;
uchar		NetArpWaitPacketBuf[PKTSIZE_ALIGN + PKTALIGN];
ulong		NetArpWaitTimerStart;
int		NetArpWaitTry;

void ArpRequest(void)
{
	uchar *pkt;
	ARP_t *arp;

	debug("ARP broadcast %d\n", NetArpWaitTry);

	pkt = NetTxPacket;

	pkt += NetSetEther(pkt, NetBcastAddr, PROT_ARP);

	arp = (ARP_t *) pkt;

	arp->ar_hrd = htons(ARP_ETHER);
	arp->ar_pro = htons(PROT_IP);
	arp->ar_hln = 6;
	arp->ar_pln = 4;
	arp->ar_op = htons(ARPOP_REQUEST);

	/* source ET addr */
	memcpy(&arp->ar_data[0], NetOurEther, 6);
	/* source IP addr */
	NetWriteIP((uchar *) &arp->ar_data[6], NetOurIP);
	/* dest ET addr = 0 */
	memset(&arp->ar_data[10], '\0', 6);
	if ((NetArpWaitPacketIP & NetOurSubnetMask) !=
	    (NetOurIP & NetOurSubnetMask)) {
		if (NetOurGatewayIP == 0) {
			puts("## Warning: gatewayip needed but not set\n");
			NetArpWaitReplyIP = NetArpWaitPacketIP;
		} else {
			NetArpWaitReplyIP = NetOurGatewayIP;
		}
	} else {
		NetArpWaitReplyIP = NetArpWaitPacketIP;
	}

	NetWriteIP((uchar *) &arp->ar_data[16], NetArpWaitReplyIP);
	(void) eth_send(NetTxPacket, (pkt - NetTxPacket) + ARP_HDR_SIZE);
}

void ArpTimeoutCheck(void)
{
	ulong t;

	if (!NetArpWaitPacketIP)
		return;

	t = get_timer(0);

	/* check for arp timeout */
	if ((t - NetArpWaitTimerStart) > ARP_TIMEOUT) {
		NetArpWaitTry++;

		if (NetArpWaitTry >= ARP_TIMEOUT_COUNT) {
			puts("\nARP Retry count exceeded; starting again\n");
			NetArpWaitTry = 0;
			NetStartAgain();
		} else {
			NetArpWaitTimerStart = t;
			ArpRequest();
		}
	}
}

/*
 * Check if autoload is enabled. If so, use either NFS or TFTP to download
 * the boot file.
 */
void net_auto_load(void)
{
	const char *s = getenv("autoload");

	if (s != NULL) {
		if (*s == 'n') {
			/*
			 * Just use BOOTP/RARP to configure system;
			 * Do not use TFTP to load the bootfile.
			 */
			NetState = NETLOOP_SUCCESS;
			return;
		}
#if defined(CONFIG_CMD_NFS)
		if (strcmp(s, "NFS") == 0) {
			/*
			 * Use NFS to load the bootfile.
			 */
			NfsStart();
			return;
		}
#endif
	}
	TftpStart(TFTPGET);
}

static void NetInitLoop(enum proto_t protocol)
{
	static int env_changed_id;
	int env_id = get_env_id();

	/* update only when the environment has changed */
	if (env_changed_id != env_id) {
		NetOurIP = getenv_IPaddr("ipaddr");
		NetOurGatewayIP = getenv_IPaddr("gatewayip");
		NetOurSubnetMask = getenv_IPaddr("netmask");
		NetServerIP = getenv_IPaddr("serverip");
		NetOurNativeVLAN = getenv_VLAN("nvlan");
		NetOurVLAN = getenv_VLAN("vlan");
#if defined(CONFIG_CMD_DNS)
		NetOurDNSIP = getenv_IPaddr("dnsip");
#endif
		env_changed_id = env_id;
	}

	return;
}

/**********************************************************************/
/*
 *	Main network processing loop.
 */

int NetLoop(enum proto_t protocol)
{
	bd_t *bd = gd->bd;
	int ret = -1;

	NetRestarted = 0;
	NetDevExists = 0;

	/* XXX problem with bss workaround */
	NetArpWaitPacketMAC = NULL;
	NetArpWaitTxPacket = NULL;
	NetArpWaitPacketIP = 0;
	NetArpWaitReplyIP = 0;
	NetArpWaitTxPacket = NULL;
	NetTxPacket = NULL;
	NetTryCount = 1;

	if (!NetTxPacket) {
		int	i;
		/*
		 *	Setup packet buffers, aligned correctly.
		 */
		NetTxPacket = &PktBuf[0] + (PKTALIGN - 1);
		NetTxPacket -= (ulong)NetTxPacket % PKTALIGN;
		for (i = 0; i < PKTBUFSRX; i++)
			NetRxPackets[i] = NetTxPacket + (i+1)*PKTSIZE_ALIGN;
	}

	if (!NetArpWaitTxPacket) {
		NetArpWaitTxPacket = &NetArpWaitPacketBuf[0] + (PKTALIGN - 1);
		NetArpWaitTxPacket -= (ulong)NetArpWaitTxPacket % PKTALIGN;
		NetArpWaitTxPacketSize = 0;
	}

	bootstage_mark_name(BOOTSTAGE_ID_ETH_START, "eth_start");
	eth_halt();
	eth_set_current();
	if (eth_init(bd) < 0) {
		eth_halt();
		return -1;
	}

restart:
	memcpy(NetOurEther, eth_get_dev()->enetaddr, 6);

	NetState = NETLOOP_CONTINUE;

	/*
	 *	Start the ball rolling with the given start function.  From
	 *	here on, this code is a state machine driven by received
	 *	packets and timer events.
	 */
	NetInitLoop(protocol);

	switch (net_check_prereq(protocol)) {
	case 1:
		/* network not configured */
		eth_halt();
		return -1;

	case 2:
		/* network device not configured */
		break;

	case 0:
		NetDevExists = 1;
		NetBootFileXferSize = 0;
		switch (protocol) {
		case TFTPGET:
#ifdef CONFIG_CMD_TFTPPUT
		case TFTPPUT:
#endif
			/* always use ARP to get server ethernet address */
			TftpStart(protocol);
			break;
#ifdef CONFIG_CMD_TFTPSRV
		case TFTPSRV:
			TftpStartServer();
			break;
#endif
#if defined(CONFIG_CMD_DHCP)
		case DHCP:
			BootpTry = 0;
			NetOurIP = 0;
			DhcpRequest();		/* Basically same as BOOTP */
			break;
#endif

		case BOOTP:
			BootpTry = 0;
			NetOurIP = 0;
			BootpRequest();
			break;

#if defined(CONFIG_CMD_RARP)
		case RARP:
			RarpTry = 0;
			NetOurIP = 0;
			RarpRequest();
			break;
#endif
#if defined(CONFIG_CMD_PING)
		case PING:
			PingStart();
			break;
#endif
#if defined(CONFIG_CMD_NFS)
		case NFS:
			NfsStart();
			break;
#endif
#if defined(CONFIG_CMD_CDP)
		case CDP:
			CDPStart();
			break;
#endif
#ifdef CONFIG_NETCONSOLE
		case NETCONS:
			NcStart();
			break;
#endif
#if defined(CONFIG_CMD_SNTP)
		case SNTP:
			SntpStart();
			break;
#endif
#if defined(CONFIG_CMD_DNS)
		case DNS:
			DnsStart();
			break;
#endif
		default:
			break;
		}

		break;
	}

#if defined(CONFIG_MII) || defined(CONFIG_CMD_MII)
#if	defined(CONFIG_SYS_FAULT_ECHO_LINK_DOWN)	&& \
	defined(CONFIG_STATUS_LED)			&& \
	defined(STATUS_LED_RED)
	/*
	 * Echo the inverted link state to the fault LED.
	 */
	if (miiphy_link(eth_get_dev()->name, CONFIG_SYS_FAULT_MII_ADDR))
		status_led_set(STATUS_LED_RED, STATUS_LED_OFF);
	else
		status_led_set(STATUS_LED_RED, STATUS_LED_ON);
#endif /* CONFIG_SYS_FAULT_ECHO_LINK_DOWN, ... */
#endif /* CONFIG_MII, ... */

	/*
	 *	Main packet reception loop.  Loop receiving packets until
	 *	someone sets `NetState' to a state that terminates.
	 */
	for (;;) {
		WATCHDOG_RESET();
#ifdef CONFIG_SHOW_ACTIVITY
		show_activity(1);
#endif
		/*
		 *	Check the ethernet for a new packet.  The ethernet
		 *	receive routine will process it.
		 */
		eth_rx();

		/*
		 *	Abort if ctrl-c was pressed.
		 */
		if (ctrlc()) {
			eth_halt();
			puts("\nAbort\n");
			goto done;
		}

		ArpTimeoutCheck();

		/*
		 *	Check for a timeout, and run the timeout handler
		 *	if we have one.
		 */
		if (timeHandler && ((get_timer(0) - timeStart) > timeDelta)) {
			thand_f *x;

#if defined(CONFIG_MII) || defined(CONFIG_CMD_MII)
#if	defined(CONFIG_SYS_FAULT_ECHO_LINK_DOWN)	&& \
	defined(CONFIG_STATUS_LED)			&& \
	defined(STATUS_LED_RED)
			/*
			 * Echo the inverted link state to the fault LED.
			 */
			if (miiphy_link(eth_get_dev()->name,
				       CONFIG_SYS_FAULT_MII_ADDR)) {
				status_led_set(STATUS_LED_RED, STATUS_LED_OFF);
			} else {
				status_led_set(STATUS_LED_RED, STATUS_LED_ON);
			}
#endif /* CONFIG_SYS_FAULT_ECHO_LINK_DOWN, ... */
#endif /* CONFIG_MII, ... */
			x = timeHandler;
			timeHandler = (thand_f *)0;
			(*x)();
		}


		switch (NetState) {

		case NETLOOP_RESTART:
			NetRestarted = 1;
			goto restart;

		case NETLOOP_SUCCESS:
			if (NetBootFileXferSize > 0) {
				char buf[20];
				printf("Bytes transferred = %ld (%lx hex)\n",
					NetBootFileXferSize,
					NetBootFileXferSize);
				sprintf(buf, "%lX", NetBootFileXferSize);
				setenv("filesize", buf);

				sprintf(buf, "%lX", (unsigned long)load_addr);
				setenv("fileaddr", buf);
			}
			eth_halt();
			ret = NetBootFileXferSize;
			goto done;

		case NETLOOP_FAIL:
			goto done;
		}
	}

done:
#ifdef CONFIG_CMD_TFTPPUT
	/* Clear out the handlers */
	NetSetHandler(NULL);
	net_set_icmp_handler(NULL);
#endif
	return ret;
}

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

static void
startAgainTimeout(void)
{
	NetState = NETLOOP_RESTART;
}

static void
startAgainHandler(uchar *pkt, unsigned dest, IPaddr_t sip,
		  unsigned src, unsigned len)
{
	/* Totally ignore the packet */
}

void NetStartAgain(void)
{
	char *nretry;
	int retry_forever = 0;
	unsigned long retrycnt = 0;

	nretry = getenv("netretry");
	if (nretry) {
		if (!strcmp(nretry, "yes"))
			retry_forever = 1;
		else if (!strcmp(nretry, "no"))
			retrycnt = 0;
		else if (!strcmp(nretry, "once"))
			retrycnt = 1;
		else
			retrycnt = simple_strtoul(nretry, NULL, 0);
	} else
		retry_forever = 1;

	if ((!retry_forever) && (NetTryCount >= retrycnt)) {
		eth_halt();
		NetState = NETLOOP_FAIL;
		return;
	}

	NetTryCount++;

	eth_halt();
#if !defined(CONFIG_NET_DO_NOT_TRY_ANOTHER)
	eth_try_another(!NetRestarted);
#endif
	eth_init(gd->bd);
	if (NetRestartWrap) {
		NetRestartWrap = 0;
		if (NetDevExists) {
			NetSetTimeout(10000UL, startAgainTimeout);
			NetSetHandler(startAgainHandler);
		} else {
			NetState = NETLOOP_FAIL;
		}
	} else {
		NetState = NETLOOP_RESTART;
	}
}

/**********************************************************************/
/*
 *	Miscelaneous bits.
 */

void
NetSetHandler(rxhand_f *f)
{
	packetHandler = f;
}

#ifdef CONFIG_CMD_TFTPPUT
void net_set_icmp_handler(rxhand_icmp_f *f)
{
	packet_icmp_handler = f;
}
#endif

void
NetSetTimeout(ulong iv, thand_f *f)
{
	if (iv == 0) {
		timeHandler = (thand_f *)0;
	} else {
		timeHandler = f;
		timeStart = get_timer(0);
		timeDelta = iv;
	}
}


void
NetSendPacket(uchar *pkt, int len)
{
	(void) eth_send(pkt, len);
}

int
NetSendUDPPacket(uchar *ether, IPaddr_t dest, int dport, int sport, int len)
{
	uchar *pkt;

	/* convert to new style broadcast */
	if (dest == 0)
		dest = 0xFFFFFFFF;

	/* if broadcast, make the ether address a broadcast and don't do ARP */
	if (dest == 0xFFFFFFFF)
		ether = NetBcastAddr;

	/*
	 * if MAC address was not discovered yet, save the packet and do
	 * an ARP request
	 */
	if (memcmp(ether, NetEtherNullAddr, 6) == 0) {

		debug("sending ARP for %08x\n", dest);

		NetArpWaitPacketIP = dest;
		NetArpWaitPacketMAC = ether;

		pkt = NetArpWaitTxPacket;
		pkt += NetSetEther(pkt, NetArpWaitPacketMAC, PROT_IP);

		NetSetIP(pkt, dest, dport, sport, len);
		memcpy(pkt + IP_HDR_SIZE, (uchar *)NetTxPacket +
		       (pkt - (uchar *)NetArpWaitTxPacket) + IP_HDR_SIZE, len);

		/* size of the waiting packet */
		NetArpWaitTxPacketSize = (pkt - NetArpWaitTxPacket) +
			IP_HDR_SIZE + len;

		/* and do the ARP request */
		NetArpWaitTry = 1;
		NetArpWaitTimerStart = get_timer(0);
		ArpRequest();
		return 1;	/* waiting */
	}

	debug("sending UDP to %08x/%pM\n", dest, ether);

	pkt = (uchar *)NetTxPacket;
	pkt += NetSetEther(pkt, ether, PROT_IP);
	NetSetIP(pkt, dest, dport, sport, len);
	(void) eth_send(NetTxPacket, (pkt - NetTxPacket) + IP_HDR_SIZE + len);

	return 0;	/* transmitted */
}

#if defined(CONFIG_CMD_PING)
static ushort PingSeqNo;

int PingSend(void)
{
	static uchar mac[6];
	IP_t *ip;
	ushort *s;
	uchar *pkt;

	/* XXX always send arp request */

	memcpy(mac, NetEtherNullAddr, 6);

	debug("sending ARP for %08x\n", NetPingIP);

	NetArpWaitPacketIP = NetPingIP;
	NetArpWaitPacketMAC = mac;

	pkt = NetArpWaitTxPacket;
	pkt += NetSetEther(pkt, mac, PROT_IP);

	ip = (IP_t *)pkt;

	/*
	 * Construct an IP and ICMP header.
	 * (need to set no fragment bit - XXX)
	 */
	/* IP_HDR_SIZE / 4 (not including UDP) */
	ip->ip_hl_v  = 0x45;
	ip->ip_tos   = 0;
	ip->ip_len   = htons(IP_HDR_SIZE_NO_UDP + 8);
	ip->ip_id    = htons(NetIPID++);
	ip->ip_off   = htons(IP_FLAGS_DFRAG);	/* Don't fragment */
	ip->ip_ttl   = 255;
	ip->ip_p     = 0x01;		/* ICMP */
	ip->ip_sum   = 0;
	/* already in network byte order */
	NetCopyIP((void *)&ip->ip_src, &NetOurIP);
	/* - "" - */
	NetCopyIP((void *)&ip->ip_dst, &NetPingIP);
	ip->ip_sum   = ~NetCksum((uchar *)ip, IP_HDR_SIZE_NO_UDP / 2);

	s = &ip->udp_src;		/* XXX ICMP starts here */
	s[0] = htons(0x0800);		/* echo-request, code */
	s[1] = 0;			/* checksum */
	s[2] = 0;			/* identifier */
	s[3] = htons(PingSeqNo++);	/* sequence number */
	s[1] = ~NetCksum((uchar *)s, 8/2);

	/* size of the waiting packet */
	NetArpWaitTxPacketSize =
		(pkt - NetArpWaitTxPacket) + IP_HDR_SIZE_NO_UDP + 8;

	/* and do the ARP request */
	NetArpWaitTry = 1;
	NetArpWaitTimerStart = get_timer(0);
	ArpRequest();
	return 1;	/* waiting */
}

static void
PingTimeout(void)
{
	eth_halt();
	NetState = NETLOOP_FAIL;	/* we did not get the reply */
}

static void
PingHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src,
	    unsigned len)
{
	if (sip != NetPingIP)
		return;

	NetState = NETLOOP_SUCCESS;
}

static void PingStart(void)
{
	printf("Using %s device\n", eth_get_name());
	NetSetTimeout(10000UL, PingTimeout);
	NetSetHandler(PingHandler);

	PingSend();
}
#endif

#ifdef CONFIG_IP_DEFRAG
/*
 * This function collects fragments in a single packet, according
 * to the algorithm in RFC815. It returns NULL or the pointer to
 * a complete packet, in static storage
 */
#ifndef CONFIG_NET_MAXDEFRAG
#define CONFIG_NET_MAXDEFRAG 16384
#endif
/*
 * MAXDEFRAG, above, is chosen in the config file and  is real data
 * so we need to add the NFS overhead, which is more than TFTP.
 * To use sizeof in the internal unnamed structures, we need a real
 * instance (can't do "sizeof(struct rpc_t.u.reply))", unfortunately).
 * The compiler doesn't complain nor allocates the actual structure
 */
static struct rpc_t rpc_specimen;
#define IP_PKTSIZE (CONFIG_NET_MAXDEFRAG + sizeof(rpc_specimen.u.reply))

#define IP_MAXUDP (IP_PKTSIZE - IP_HDR_SIZE_NO_UDP)

/*
 * this is the packet being assembled, either data or frag control.
 * Fragments go by 8 bytes, so this union must be 8 bytes long
 */
struct hole {
	/* first_byte is address of this structure */
	u16 last_byte;	/* last byte in this hole + 1 (begin of next hole) */
	u16 next_hole;	/* index of next (in 8-b blocks), 0 == none */
	u16 prev_hole;	/* index of prev, 0 == none */
	u16 unused;
};

static IP_t *__NetDefragment(IP_t *ip, int *lenp)
{
	static uchar pkt_buff[IP_PKTSIZE] __aligned(PKTALIGN);
	static u16 first_hole, total_len;
	struct hole *payload, *thisfrag, *h, *newh;
	IP_t *localip = (IP_t *)pkt_buff;
	uchar *indata = (uchar *)ip;
	int offset8, start, len, done = 0;
	u16 ip_off = ntohs(ip->ip_off);

	/* payload starts after IP header, this fragment is in there */
	payload = (struct hole *)(pkt_buff + IP_HDR_SIZE_NO_UDP);
	offset8 =  (ip_off & IP_OFFS);
	thisfrag = payload + offset8;
	start = offset8 * 8;
	len = ntohs(ip->ip_len) - IP_HDR_SIZE_NO_UDP;

	if (start + len > IP_MAXUDP) /* fragment extends too far */
		return NULL;

	if (!total_len || localip->ip_id != ip->ip_id) {
		/* new (or different) packet, reset structs */
		total_len = 0xffff;
		payload[0].last_byte = ~0;
		payload[0].next_hole = 0;
		payload[0].prev_hole = 0;
		first_hole = 0;
		/* any IP header will work, copy the first we received */
		memcpy(localip, ip, IP_HDR_SIZE_NO_UDP);
	}

	/*
	 * What follows is the reassembly algorithm. We use the payload
	 * array as a linked list of hole descriptors, as each hole starts
	 * at a multiple of 8 bytes. However, last byte can be whatever value,
	 * so it is represented as byte count, not as 8-byte blocks.
	 */

	h = payload + first_hole;
	while (h->last_byte < start) {
		if (!h->next_hole) {
			/* no hole that far away */
			return NULL;
		}
		h = payload + h->next_hole;
	}

	/* last fragment may be 1..7 bytes, the "+7" forces acceptance */
	if (offset8 + ((len + 7) / 8) <= h - payload) {
		/* no overlap with holes (dup fragment?) */
		return NULL;
	}

	if (!(ip_off & IP_FLAGS_MFRAG)) {
		/* no more fragmentss: truncate this (last) hole */
		total_len = start + len;
		h->last_byte = start + len;
	}

	/*
	 * There is some overlap: fix the hole list. This code doesn't
	 * deal with a fragment that overlaps with two different holes
	 * (thus being a superset of a previously-received fragment).
	 */

	if ((h >= thisfrag) && (h->last_byte <= start + len)) {
		/* complete overlap with hole: remove hole */
		if (!h->prev_hole && !h->next_hole) {
			/* last remaining hole */
			done = 1;
		} else if (!h->prev_hole) {
			/* first hole */
			first_hole = h->next_hole;
			payload[h->next_hole].prev_hole = 0;
		} else if (!h->next_hole) {
			/* last hole */
			payload[h->prev_hole].next_hole = 0;
		} else {
			/* in the middle of the list */
			payload[h->next_hole].prev_hole = h->prev_hole;
			payload[h->prev_hole].next_hole = h->next_hole;
		}

	} else if (h->last_byte <= start + len) {
		/* overlaps with final part of the hole: shorten this hole */
		h->last_byte = start;

	} else if (h >= thisfrag) {
		/* overlaps with initial part of the hole: move this hole */
		newh = thisfrag + (len / 8);
		*newh = *h;
		h = newh;
		if (h->next_hole)
			payload[h->next_hole].prev_hole = (h - payload);
		if (h->prev_hole)
			payload[h->prev_hole].next_hole = (h - payload);
		else
			first_hole = (h - payload);

	} else {
		/* fragment sits in the middle: split the hole */
		newh = thisfrag + (len / 8);
		*newh = *h;
		h->last_byte = start;
		h->next_hole = (newh - payload);
		newh->prev_hole = (h - payload);
		if (newh->next_hole)
			payload[newh->next_hole].prev_hole = (newh - payload);
	}

	/* finally copy this fragment and possibly return whole packet */
	memcpy((uchar *)thisfrag, indata + IP_HDR_SIZE_NO_UDP, len);
	if (!done)
		return NULL;

	localip->ip_len = htons(total_len);
	*lenp = total_len + IP_HDR_SIZE_NO_UDP;
	return localip;
}

static inline IP_t *NetDefragment(IP_t *ip, int *lenp)
{
	u16 ip_off = ntohs(ip->ip_off);
	if (!(ip_off & (IP_OFFS | IP_FLAGS_MFRAG)))
		return ip; /* not a fragment */
	return __NetDefragment(ip, lenp);
}

#else /* !CONFIG_IP_DEFRAG */

static inline IP_t *NetDefragment(IP_t *ip, int *lenp)
{
	u16 ip_off = ntohs(ip->ip_off);
	if (!(ip_off & (IP_OFFS | IP_FLAGS_MFRAG)))