#include <asm/uaccess.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/highmem.h>
#include <linux/slab.h>

#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>

#include <net/snmp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/xfrm.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/icmp.h>
#include <net/checksum.h>
#include <net/inetpeer.h>
#include <linux/igmp.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_bridge.h>
#include <linux/mroute.h>
#include <linux/netlink.h>
#include <linux/tcp.h>

int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
EXPORT_SYMBOL(sysctl_ip_default_ttl);

__inline__ void ip_send_check(struct iphdr *iph)
{
	iph->check = 0;
	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
}
EXPORT_SYMBOL(ip_send_check);

int __ip_local_out(struct sk_buff *skb)
{
	struct iphdr *iph = ip_hdr(skb);

	iph->tot_len = htons(skb->len);
	ip_send_check(iph);
	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
		       skb_dst(skb)->dev, dst_output);
}

int ip_local_out(struct sk_buff *skb)
{
	int err;

	err = __ip_local_out(skb);
	if (likely(err == 1))
		err = dst_output(skb);

	return err;
}
EXPORT_SYMBOL_GPL(ip_local_out);

static int ip_dev_loopback_xmit(struct sk_buff *newskb)
{
	skb_reset_mac_header(newskb);
	__skb_pull(newskb, skb_network_offset(newskb));
	newskb->pkt_type = PACKET_LOOPBACK;
	newskb->ip_summed = CHECKSUM_UNNECESSARY;
	WARN_ON(!skb_dst(newskb));
	skb_dst_force(newskb);
	netif_rx_ni(newskb);
	return 0;
}

static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
{
	int ttl = inet->uc_ttl;

	if (ttl < 0)
		ttl = ip4_dst_hoplimit(dst);
	return ttl;
}

int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
			  __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
{
	struct inet_sock *inet = inet_sk(sk);
	struct rtable *rt = skb_rtable(skb);
	struct iphdr *iph;

	
	skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
	skb_reset_network_header(skb);
	iph = ip_hdr(skb);
	iph->version  = 4;
	iph->ihl      = 5;
	iph->tos      = inet->tos;
	if (ip_dont_fragment(sk, &rt->dst))
		iph->frag_off = htons(IP_DF);
	else
		iph->frag_off = 0;
	iph->ttl      = ip_select_ttl(inet, &rt->dst);
	iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
	iph->saddr    = saddr;
	iph->protocol = sk->sk_protocol;
	ip_select_ident(skb, sk);

	if (opt && opt->opt.optlen) {
		iph->ihl += opt->opt.optlen>>2;
		ip_options_build(skb, &opt->opt, daddr, rt, 0);
	}

	skb->priority = sk->sk_priority;
	skb->mark = sk->sk_mark;

	
	return ip_local_out(skb);
}
EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);

static inline int ip_finish_output2(struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	struct rtable *rt = (struct rtable *)dst;
	struct net_device *dev = dst->dev;
	unsigned int hh_len = LL_RESERVED_SPACE(dev);
	struct neighbour *neigh;

	if (rt->rt_type == RTN_MULTICAST) {
		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
	} else if (rt->rt_type == RTN_BROADCAST)
		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);

	
	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
		struct sk_buff *skb2;

		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
		if (skb2 == NULL) {
			kfree_skb(skb);
			return -ENOMEM;
		}
		if (skb->sk)
			skb_set_owner_w(skb2, skb->sk);
		kfree_skb(skb);
		skb = skb2;
	}

	rcu_read_lock();
	neigh = dst_get_neighbour_noref(dst);
	if (neigh) {
		int res = neigh_output(neigh, skb);

		rcu_read_unlock();
		return res;
	}
	rcu_read_unlock();

	if (net_ratelimit())
		printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
	kfree_skb(skb);
	return -EINVAL;
}

static inline int ip_skb_dst_mtu(struct sk_buff *skb)
{
	struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;

	return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
	       skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
}

static int ip_finish_output(struct sk_buff *skb)
{
#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
	
	if (skb_dst(skb)->xfrm != NULL) {
		IPCB(skb)->flags |= IPSKB_REROUTED;
		return dst_output(skb);
	}
#endif
	if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
		return ip_fragment(skb, ip_finish_output2);
	else
		return ip_finish_output2(skb);
}

int ip_mc_output(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;
	struct rtable *rt = skb_rtable(skb);
	struct net_device *dev = rt->dst.dev;

	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);

	skb->dev = dev;
	skb->protocol = htons(ETH_P_IP);


	if (rt->rt_flags&RTCF_MULTICAST) {
		if (sk_mc_loop(sk)
#ifdef CONFIG_IP_MROUTE
		    &&
		    ((rt->rt_flags & RTCF_LOCAL) ||
		     !(IPCB(skb)->flags & IPSKB_FORWARDED))
#endif
		   ) {
			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
			if (newskb)
				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
					newskb, NULL, newskb->dev,
					ip_dev_loopback_xmit);
		}

		

		if (ip_hdr(skb)->ttl == 0) {
			kfree_skb(skb);
			return 0;
		}
	}

	if (rt->rt_flags&RTCF_BROADCAST) {
		struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
		if (newskb)
			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
				NULL, newskb->dev, ip_dev_loopback_xmit);
	}

	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
			    skb->dev, ip_finish_output,
			    !(IPCB(skb)->flags & IPSKB_REROUTED));
}

int ip_output(struct sk_buff *skb)
{
	struct net_device *dev = skb_dst(skb)->dev;

	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);

	skb->dev = dev;
	skb->protocol = htons(ETH_P_IP);

	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
			    ip_finish_output,
			    !(IPCB(skb)->flags & IPSKB_REROUTED));
}

static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
{
	BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
		     offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
	memcpy(&iph->saddr, &fl4->saddr,
	       sizeof(fl4->saddr) + sizeof(fl4->daddr));
}

int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
{
	struct sock *sk = skb->sk;
	struct inet_sock *inet = inet_sk(sk);
	struct ip_options_rcu *inet_opt;
	struct flowi4 *fl4;
	struct rtable *rt;
	struct iphdr *iph;
	int res;

	rcu_read_lock();
	inet_opt = rcu_dereference(inet->inet_opt);
	fl4 = &fl->u.ip4;
	rt = skb_rtable(skb);
	if (rt != NULL)
		goto packet_routed;

	
	rt = (struct rtable *)__sk_dst_check(sk, 0);
	if (rt == NULL) {
		__be32 daddr;

		
		daddr = inet->inet_daddr;
		if (inet_opt && inet_opt->opt.srr)
			daddr = inet_opt->opt.faddr;

		rt = ip_route_output_ports(sock_net(sk), fl4, sk,
					   daddr, inet->inet_saddr,
					   inet->inet_dport,
					   inet->inet_sport,
					   sk->sk_protocol,
					   RT_CONN_FLAGS(sk),
					   sk->sk_bound_dev_if);
		if (IS_ERR(rt))
			goto no_route;
		sk_setup_caps(sk, &rt->dst);
	}
	skb_dst_set_noref(skb, &rt->dst);

packet_routed:
	if (inet_opt && inet_opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
		goto no_route;

	
	skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
	skb_reset_network_header(skb);
	iph = ip_hdr(skb);
	*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
	if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
		iph->frag_off = htons(IP_DF);
	else
		iph->frag_off = 0;
	iph->ttl      = ip_select_ttl(inet, &rt->dst);
	iph->protocol = sk->sk_protocol;
	ip_copy_addrs(iph, fl4);

	

	if (inet_opt && inet_opt->opt.optlen) {
		iph->ihl += inet_opt->opt.optlen >> 2;
		ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
	}

	ip_select_ident_segs(skb, sk, skb_shinfo(skb)->gso_segs ?: 1);

	skb->priority = sk->sk_priority;
	skb->mark = sk->sk_mark;

	res = ip_local_out(skb);
	rcu_read_unlock();
	return res;

no_route:
	rcu_read_unlock();
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
	kfree_skb(skb);
	return -EHOSTUNREACH;
}
EXPORT_SYMBOL(ip_queue_xmit);


static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
{
	to->pkt_type = from->pkt_type;
	to->priority = from->priority;
	to->protocol = from->protocol;
	skb_dst_drop(to);
	skb_dst_copy(to, from);
	to->dev = from->dev;
	to->mark = from->mark;

	
	IPCB(to)->flags = IPCB(from)->flags;

#ifdef CONFIG_NET_SCHED
	to->tc_index = from->tc_index;
#endif
	nf_copy(to, from);
#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
	to->nf_trace = from->nf_trace;
#endif
#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
	to->ipvs_property = from->ipvs_property;
#endif
	skb_copy_secmark(to, from);
}


int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
{
	struct iphdr *iph;
	int ptr;
	struct net_device *dev;
	struct sk_buff *skb2;
	unsigned int mtu, hlen, left, len, ll_rs;
	int offset;
	__be16 not_last_frag;
	struct rtable *rt = skb_rtable(skb);
	int err = 0;

	dev = rt->dst.dev;


	iph = ip_hdr(skb);

	if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
			  htonl(ip_skb_dst_mtu(skb)));
		kfree_skb(skb);
		return -EMSGSIZE;
	}


	hlen = iph->ihl * 4;
	mtu = dst_mtu(&rt->dst) - hlen;	
#ifdef CONFIG_BRIDGE_NETFILTER
	if (skb->nf_bridge)
		mtu -= nf_bridge_mtu_reduction(skb);
#endif
	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;

	if (skb_has_frag_list(skb)) {
		struct sk_buff *frag, *frag2;
		int first_len = skb_pagelen(skb);

		if (first_len - hlen > mtu ||
		    ((first_len - hlen) & 7) ||
		    ip_is_fragment(iph) ||
		    skb_cloned(skb))
			goto slow_path;

		skb_walk_frags(skb, frag) {
			
			if (frag->len > mtu ||
			    ((frag->len & 7) && frag->next) ||
			    skb_headroom(frag) < hlen)
				goto slow_path_clean;

			
			if (skb_shared(frag))
				goto slow_path_clean;

			BUG_ON(frag->sk);
			if (skb->sk) {
				frag->sk = skb->sk;
				frag->destructor = sock_wfree;
			}
			skb->truesize -= frag->truesize;
		}

		

		err = 0;
		offset = 0;
		frag = skb_shinfo(skb)->frag_list;
		skb_frag_list_init(skb);
		skb->data_len = first_len - skb_headlen(skb);
		skb->len = first_len;
		iph->tot_len = htons(first_len);
		iph->frag_off = htons(IP_MF);
		ip_send_check(iph);

		for (;;) {
			if (frag) {
				frag->ip_summed = CHECKSUM_NONE;
				skb_reset_transport_header(frag);
				__skb_push(frag, hlen);
				skb_reset_network_header(frag);
				memcpy(skb_network_header(frag), iph, hlen);
				iph = ip_hdr(frag);
				iph->tot_len = htons(frag->len);
				ip_copy_metadata(frag, skb);
				if (offset == 0)
					ip_options_fragment(frag);
				offset += skb->len - hlen;
				iph->frag_off = htons(offset>>3);
				if (frag->next != NULL)
					iph->frag_off |= htons(IP_MF);
				
				ip_send_check(iph);
			}

			err = output(skb);

			if (!err)
				IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
			if (err || !frag)
				break;

			skb = frag;
			frag = skb->next;
			skb->next = NULL;
		}

		if (err == 0) {
			IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
			return 0;
		}

		while (frag) {
			skb = frag->next;
			kfree_skb(frag);
			frag = skb;
		}
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
		return err;

slow_path_clean:
		skb_walk_frags(skb, frag2) {
			if (frag2 == frag)
				break;
			frag2->sk = NULL;
			frag2->destructor = NULL;
			skb->truesize += frag2->truesize;
		}
	}

slow_path:
	left = skb->len - hlen;		
	ptr = hlen;		

	ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));


	offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
	not_last_frag = iph->frag_off & htons(IP_MF);


	while (left > 0) {
		len = left;
		
		if (len > mtu)
			len = mtu;
		if (len < left)	{
			len &= ~7;
		}

		if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
			NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
			err = -ENOMEM;
			goto fail;
		}


		ip_copy_metadata(skb2, skb);
		skb_reserve(skb2, ll_rs);
		skb_put(skb2, len + hlen);
		skb_reset_network_header(skb2);
		skb2->transport_header = skb2->network_header + hlen;


		if (skb->sk)
			skb_set_owner_w(skb2, skb->sk);


		skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);

		if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
			BUG();
		left -= len;

		iph = ip_hdr(skb2);
		iph->frag_off = htons((offset >> 3));

		if (offset == 0)
			ip_options_fragment(skb);

		if (left > 0 || not_last_frag)
			iph->frag_off |= htons(IP_MF);
		ptr += len;
		offset += len;

		iph->tot_len = htons(len + hlen);

		ip_send_check(iph);

		err = output(skb2);
		if (err)
			goto fail;

		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
	}
	kfree_skb(skb);
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
	return err;

fail:
	kfree_skb(skb);
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
	return err;
}
EXPORT_SYMBOL(ip_fragment);

int
ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
	struct iovec *iov = from;

	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		if (memcpy_fromiovecend(to, iov, offset, len) < 0)
			return -EFAULT;
	} else {
		__wsum csum = 0;
		if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
			return -EFAULT;
		skb->csum = csum_block_add(skb->csum, csum, odd);
	}
	return 0;
}
EXPORT_SYMBOL(ip_generic_getfrag);

static inline __wsum
csum_page(struct page *page, int offset, int copy)
{
	char *kaddr;
	__wsum csum;
	kaddr = kmap(page);
	csum = csum_partial(kaddr + offset, copy, 0);
	kunmap(page);
	return csum;
}

static inline int ip_ufo_append_data(struct sock *sk,
			struct sk_buff_head *queue,
			int getfrag(void *from, char *to, int offset, int len,
			       int odd, struct sk_buff *skb),
			void *from, int length, int hh_len, int fragheaderlen,
			int transhdrlen, int maxfraglen, unsigned int flags)
{
	struct sk_buff *skb;
	int err;

	if ((skb = skb_peek_tail(queue)) == NULL) {
		skb = sock_alloc_send_skb(sk,
			hh_len + fragheaderlen + transhdrlen + 20,
			(flags & MSG_DONTWAIT), &err);

		if (skb == NULL)
			return err;

		
		skb_reserve(skb, hh_len);

		
		skb_put(skb, fragheaderlen + transhdrlen);

		
		skb_reset_network_header(skb);

		
		skb->transport_header = skb->network_header + fragheaderlen;

		skb->ip_summed = CHECKSUM_PARTIAL;
		skb->csum = 0;

		
		skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
		__skb_queue_tail(queue, skb);
	}

	return skb_append_datato_frags(sk, skb, getfrag, from,
				       (length - transhdrlen));
}

static int __ip_append_data(struct sock *sk,
			    struct flowi4 *fl4,
			    struct sk_buff_head *queue,
			    struct inet_cork *cork,
			    int getfrag(void *from, char *to, int offset,
					int len, int odd, struct sk_buff *skb),
			    void *from, int length, int transhdrlen,
			    unsigned int flags)
{
	struct inet_sock *inet = inet_sk(sk);
	struct sk_buff *skb;

	struct ip_options *opt = cork->opt;
	int hh_len;
	int exthdrlen;
	int mtu;
	int copy;
#ifdef CONFIG_HTC_NETWORK_MODIFY
	int err = 0;
#else
	int err;
#endif
	int offset = 0;
	unsigned int maxfraglen, fragheaderlen;
	int csummode = CHECKSUM_NONE;
	struct rtable *rt = (struct rtable *)cork->dst;

	skb = skb_peek_tail(queue);

	exthdrlen = !skb ? rt->dst.header_len : 0;
	mtu = cork->fragsize;

	hh_len = LL_RESERVED_SPACE(rt->dst.dev);

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;

	if (cork->length + length > 0xFFFF - fragheaderlen) {
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
			       mtu-exthdrlen);
		return -EMSGSIZE;
	}

	if (transhdrlen &&
	    length + fragheaderlen <= mtu &&
	    rt->dst.dev->features & NETIF_F_V4_CSUM &&
	    !exthdrlen)
		csummode = CHECKSUM_PARTIAL;

	cork->length += length;
	if (((length > mtu) || (skb && skb_is_gso(skb))) &&
	    (sk->sk_protocol == IPPROTO_UDP) &&
	    (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
					 hh_len, fragheaderlen, transhdrlen,
					 maxfraglen, flags);
		if (err)
			goto error;
		return 0;
	}


	if (!skb)
		goto alloc_new_skb;

	while (length > 0) {
		
		copy = mtu - skb->len;
		if (copy < length)
			copy = maxfraglen - skb->len;
		if (copy <= 0) {
			char *data;
			unsigned int datalen;
			unsigned int fraglen;
			unsigned int fraggap;
			unsigned int alloclen;
			struct sk_buff *skb_prev;
alloc_new_skb:
			skb_prev = skb;
			if (skb_prev)
				fraggap = skb_prev->len - maxfraglen;
			else
				fraggap = 0;

			datalen = length + fraggap;
			if (datalen > mtu - fragheaderlen)
				datalen = maxfraglen - fragheaderlen;
			fraglen = datalen + fragheaderlen;

			if ((flags & MSG_MORE) &&
			    !(rt->dst.dev->features&NETIF_F_SG))
				alloclen = mtu;
			else
				alloclen = fraglen;

			alloclen += exthdrlen;

			if (datalen == length + fraggap)
				alloclen += rt->dst.trailer_len;

			if (transhdrlen) {
				skb = sock_alloc_send_skb(sk,
						alloclen + hh_len + 15,
						(flags & MSG_DONTWAIT), &err);
			} else {
				skb = NULL;
				if (atomic_read(&sk->sk_wmem_alloc) <=
				    2 * sk->sk_sndbuf)
					skb = sock_wmalloc(sk,
							   alloclen + hh_len + 15, 1,
							   sk->sk_allocation);
				if (unlikely(skb == NULL))
					err = -ENOBUFS;
				else
					cork->tx_flags = 0;
			}
			if (skb == NULL)
				goto error;

			skb->ip_summed = csummode;
			skb->csum = 0;
			skb_reserve(skb, hh_len);
			skb_shinfo(skb)->tx_flags = cork->tx_flags;

			data = skb_put(skb, fraglen + exthdrlen);
			skb_set_network_header(skb, exthdrlen);
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
			data += fragheaderlen + exthdrlen;

			if (fraggap) {
				skb->csum = skb_copy_and_csum_bits(
					skb_prev, maxfraglen,
					data + transhdrlen, fraggap, 0);
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
				data += fraggap;
				pskb_trim_unique(skb_prev, maxfraglen);
			}

			copy = datalen - transhdrlen - fraggap;
			if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
				err = -EFAULT;
				kfree_skb(skb);
				goto error;
			}

			offset += copy;
			length -= datalen - fraggap;
			transhdrlen = 0;
			exthdrlen = 0;
			csummode = CHECKSUM_NONE;

			__skb_queue_tail(queue, skb);
			continue;
		}

		if (copy > length)
			copy = length;

		if (!(rt->dst.dev->features&NETIF_F_SG)) {
			unsigned int off;

			off = skb->len;
			if (getfrag(from, skb_put(skb, copy),
					offset, copy, off, skb) < 0) {
				__skb_trim(skb, off);
				err = -EFAULT;
				goto error;
			}
		} else {
			int i = skb_shinfo(skb)->nr_frags;
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
			struct page *page = cork->page;
			int off = cork->off;
			unsigned int left;

			if (page && (left = PAGE_SIZE - off) > 0) {
				if (copy >= left)
					copy = left;
				if (page != skb_frag_page(frag)) {
					if (i == MAX_SKB_FRAGS) {
						err = -EMSGSIZE;
						goto error;
					}
					skb_fill_page_desc(skb, i, page, off, 0);
					skb_frag_ref(skb, i);
					frag = &skb_shinfo(skb)->frags[i];
				}
			} else if (i < MAX_SKB_FRAGS) {
				if (copy > PAGE_SIZE)
					copy = PAGE_SIZE;
				page = alloc_pages(sk->sk_allocation, 0);
				if (page == NULL)  {
					err = -ENOMEM;
					goto error;
				}
				cork->page = page;
				cork->off = 0;

				skb_fill_page_desc(skb, i, page, 0, 0);
				frag = &skb_shinfo(skb)->frags[i];
			} else {
				err = -EMSGSIZE;
				goto error;
			}
			if (getfrag(from, skb_frag_address(frag)+skb_frag_size(frag),
				    offset, copy, skb->len, skb) < 0) {
				err = -EFAULT;
				goto error;
			}
			cork->off += copy;
			skb_frag_size_add(frag, copy);
			skb->len += copy;
			skb->data_len += copy;
			skb->truesize += copy;
			atomic_add(copy, &sk->sk_wmem_alloc);
		}
		offset += copy;
		length -= copy;
	}

	return 0;

error:
	cork->length -= length;
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
	return err;
}

static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
			 struct ipcm_cookie *ipc, struct rtable **rtp)
{
	struct inet_sock *inet = inet_sk(sk);
	struct ip_options_rcu *opt;
	struct rtable *rt;

	opt = ipc->opt;
	if (opt) {
		if (cork->opt == NULL) {
			cork->opt = kmalloc(sizeof(struct ip_options) + 40,
					    sk->sk_allocation);
			if (unlikely(cork->opt == NULL))
				return -ENOBUFS;
		}
		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
		cork->flags |= IPCORK_OPT;
		cork->addr = ipc->addr;
	}
	rt = *rtp;
	if (unlikely(!rt))
		return -EFAULT;
	*rtp = NULL;
	cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
			 rt->dst.dev->mtu : dst_mtu(&rt->dst);
	cork->dst = &rt->dst;
	cork->length = 0;
	cork->tx_flags = ipc->tx_flags;
	cork->page = NULL;
	cork->off = 0;

	return 0;
}

int ip_append_data(struct sock *sk, struct flowi4 *fl4,
		   int getfrag(void *from, char *to, int offset, int len,
			       int odd, struct sk_buff *skb),
		   void *from, int length, int transhdrlen,
		   struct ipcm_cookie *ipc, struct rtable **rtp,
		   unsigned int flags)
{
	struct inet_sock *inet = inet_sk(sk);
	int err;

	if (flags&MSG_PROBE)
		return 0;

	if (skb_queue_empty(&sk->sk_write_queue)) {
		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
		if (err)
			return err;
	} else {
		transhdrlen = 0;
	}

	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, getfrag,
				from, length, transhdrlen, flags);
}

ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
		       int offset, size_t size, int flags)
{
	struct inet_sock *inet = inet_sk(sk);
	struct sk_buff *skb;
	struct rtable *rt;
	struct ip_options *opt = NULL;
	struct inet_cork *cork;
	int hh_len;
	int mtu;
	int len;
	int err;
	unsigned int maxfraglen, fragheaderlen, fraggap;

	if (inet->hdrincl)
		return -EPERM;

	if (flags&MSG_PROBE)
		return 0;

	if (skb_queue_empty(&sk->sk_write_queue))
		return -EINVAL;

	cork = &inet->cork.base;
	rt = (struct rtable *)cork->dst;
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;

	if (!(rt->dst.dev->features&NETIF_F_SG))
		return -EOPNOTSUPP;

	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
	mtu = cork->fragsize;

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;

	if (cork->length + size > 0xFFFF - fragheaderlen) {
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
		return -EMSGSIZE;
	}

	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
		return -EINVAL;

	cork->length += size;
	if ((size + skb->len > mtu) &&
	    (sk->sk_protocol == IPPROTO_UDP) &&
	    (rt->dst.dev->features & NETIF_F_UFO)) {
		skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
	}


	while (size > 0) {
		int i;

		if (skb_is_gso(skb))
			len = size;
		else {

			
			len = mtu - skb->len;
			if (len < size)
				len = maxfraglen - skb->len;
		}
		if (len <= 0) {
			struct sk_buff *skb_prev;
			int alloclen;

			skb_prev = skb;
			fraggap = skb_prev->len - maxfraglen;

			alloclen = fragheaderlen + hh_len + fraggap + 15;
			skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
			if (unlikely(!skb)) {
				err = -ENOBUFS;
				goto error;
			}

			skb->ip_summed = CHECKSUM_NONE;
			skb->csum = 0;
			skb_reserve(skb, hh_len);

			skb_put(skb, fragheaderlen + fraggap);
			skb_reset_network_header(skb);
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
			if (fraggap) {
				skb->csum = skb_copy_and_csum_bits(skb_prev,
								   maxfraglen,
						    skb_transport_header(skb),
								   fraggap, 0);
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
				pskb_trim_unique(skb_prev, maxfraglen);
			}

			__skb_queue_tail(&sk->sk_write_queue, skb);
			continue;
		}

		i = skb_shinfo(skb)->nr_frags;
		if (len > size)
			len = size;
		if (skb_can_coalesce(skb, i, page, offset)) {
			skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
		} else if (i < MAX_SKB_FRAGS) {
			get_page(page);
			skb_fill_page_desc(skb, i, page, offset, len);
		} else {
			err = -EMSGSIZE;
			goto error;
		}

		if (skb->ip_summed == CHECKSUM_NONE) {
			__wsum csum;
			csum = csum_page(page, offset, len);
			skb->csum = csum_block_add(skb->csum, csum, skb->len);
		}

		skb->len += len;
		skb->data_len += len;
		skb->truesize += len;
		atomic_add(len, &sk->sk_wmem_alloc);
		offset += len;
		size -= len;
	}
	return 0;

error:
	cork->length -= size;
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
	return err;
}

static void ip_cork_release(struct inet_cork *cork)
{
	cork->flags &= ~IPCORK_OPT;
	kfree(cork->opt);
	cork->opt = NULL;
	dst_release(cork->dst);
	cork->dst = NULL;
}

struct sk_buff *__ip_make_skb(struct sock *sk,
			      struct flowi4 *fl4,
			      struct sk_buff_head *queue,
			      struct inet_cork *cork)
{
	struct sk_buff *skb, *tmp_skb;
	struct sk_buff **tail_skb;
	struct inet_sock *inet = inet_sk(sk);
	struct net *net = sock_net(sk);
	struct ip_options *opt = NULL;
	struct rtable *rt = (struct rtable *)cork->dst;
	struct iphdr *iph;
	__be16 df = 0;
	__u8 ttl;

	if ((skb = __skb_dequeue(queue)) == NULL)
		goto out;
	tail_skb = &(skb_shinfo(skb)->frag_list);

	
	if (skb->data < skb_network_header(skb))
		__skb_pull(skb, skb_network_offset(skb));
	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
		__skb_pull(tmp_skb, skb_network_header_len(skb));
		*tail_skb = tmp_skb;
		tail_skb = &(tmp_skb->next);
		skb->len += tmp_skb->len;
		skb->data_len += tmp_skb->len;
		skb->truesize += tmp_skb->truesize;
		tmp_skb->destructor = NULL;
		tmp_skb->sk = NULL;
	}

	if (inet->pmtudisc < IP_PMTUDISC_DO)
		skb->local_df = 1;

	if (inet->pmtudisc >= IP_PMTUDISC_DO ||
	    (skb->len <= dst_mtu(&rt->dst) &&
	     ip_dont_fragment(sk, &rt->dst)))
		df = htons(IP_DF);

	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;

	if (rt->rt_type == RTN_MULTICAST)
		ttl = inet->mc_ttl;
	else
		ttl = ip_select_ttl(inet, &rt->dst);

	iph = (struct iphdr *)skb->data;
	iph->version = 4;
	iph->ihl = 5;
	iph->tos = inet->tos;
	iph->frag_off = df;
	ip_select_ident(skb, sk);
	iph->ttl = ttl;
	iph->protocol = sk->sk_protocol;
	ip_copy_addrs(iph, fl4);

	if (opt) {
		iph->ihl += opt->optlen>>2;
		ip_options_build(skb, opt, cork->addr, rt, 0);
	}

	skb->priority = sk->sk_priority;
	skb->mark = sk->sk_mark;
	cork->dst = NULL;
	skb_dst_set(skb, &rt->dst);

	if (iph->protocol == IPPROTO_ICMP)
		icmp_out_count(net, ((struct icmphdr *)
			skb_transport_header(skb))->type);

	ip_cork_release(cork);
out:
	return skb;
}

int ip_send_skb(struct sk_buff *skb)
{
	struct net *net = sock_net(skb->sk);
	int err;

	err = ip_local_out(skb);
	if (err) {
		if (err > 0)
			err = net_xmit_errno(err);
		if (err)
			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
	}

	return err;
}

int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
{
	struct sk_buff *skb;

	skb = ip_finish_skb(sk, fl4);
	if (!skb)
		return 0;

	
	return ip_send_skb(skb);
}

static void __ip_flush_pending_frames(struct sock *sk,
				      struct sk_buff_head *queue,
				      struct inet_cork *cork)
{
	struct sk_buff *skb;

	while ((skb = __skb_dequeue_tail(queue)) != NULL)
		kfree_skb(skb);

	ip_cork_release(cork);
}

void ip_flush_pending_frames(struct sock *sk)
{
	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
}

struct sk_buff *ip_make_skb(struct sock *sk,
			    struct flowi4 *fl4,
			    int getfrag(void *from, char *to, int offset,
					int len, int odd, struct sk_buff *skb),
			    void *from, int length, int transhdrlen,
			    struct ipcm_cookie *ipc, struct rtable **rtp,
			    unsigned int flags)
{
	struct inet_cork cork;
	struct sk_buff_head queue;
	int err;

	if (flags & MSG_PROBE)
		return NULL;

	__skb_queue_head_init(&queue);

	cork.flags = 0;
	cork.addr = 0;
	cork.opt = NULL;
	err = ip_setup_cork(sk, &cork, ipc, rtp);
	if (err)
		return ERR_PTR(err);

	err = __ip_append_data(sk, fl4, &queue, &cork, getfrag,
			       from, length, transhdrlen, flags);
	if (err) {
		__ip_flush_pending_frames(sk, &queue, &cork);
		return ERR_PTR(err);
	}

	return __ip_make_skb(sk, fl4, &queue, &cork);
}

static int ip_reply_glue_bits(void *dptr, char *to, int offset,
			      int len, int odd, struct sk_buff *skb)
{
	__wsum csum;

	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
	skb->csum = csum_block_add(skb->csum, csum, odd);
	return 0;
}

void ip_send_reply(struct sock *sk, struct sk_buff *skb, __be32 daddr,
		   const struct ip_reply_arg *arg, unsigned int len)
{
	struct inet_sock *inet = inet_sk(sk);
	struct ip_options_data replyopts;
	struct ipcm_cookie ipc;
	struct flowi4 fl4;
	struct rtable *rt = skb_rtable(skb);

	if (ip_options_echo(&replyopts.opt.opt, skb))
		return;

	ipc.addr = daddr;
	ipc.opt = NULL;
	ipc.tx_flags = 0;

	if (replyopts.opt.opt.optlen) {
		ipc.opt = &replyopts.opt;

		if (replyopts.opt.opt.srr)
			daddr = replyopts.opt.opt.faddr;
	}

	flowi4_init_output(&fl4, arg->bound_dev_if,
			   IP4_REPLY_MARK(sock_net(sk), skb->mark),
			   RT_TOS(arg->tos),
			   RT_SCOPE_UNIVERSE, sk->sk_protocol,
			   ip_reply_arg_flowi_flags(arg),
			   daddr, rt->rt_spec_dst,
			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
	rt = ip_route_output_key(sock_net(sk), &fl4);
	if (IS_ERR(rt))
		return;

	bh_lock_sock(sk);
	inet->tos = arg->tos;
	sk->sk_priority = skb->priority;
	sk->sk_protocol = ip_hdr(skb)->protocol;
	sk->sk_bound_dev_if = arg->bound_dev_if;
	ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
		       &ipc, &rt, MSG_DONTWAIT);
	if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
		if (arg->csumoffset >= 0)
			*((__sum16 *)skb_transport_header(skb) +
			  arg->csumoffset) = csum_fold(csum_add(skb->csum,
								arg->csum));
		skb->ip_summed = CHECKSUM_NONE;
		ip_push_pending_frames(sk, &fl4);
	}

	bh_unlock_sock(sk);

	ip_rt_put(rt);
}

void __init ip_init(void)
{
	ip_rt_init();
	inet_initpeers();

#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
	igmp_mc_proc_init();
#endif
}