Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1359 insertions, 0 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
new file mode 100644
index 0000000..30ab7b6
--- /dev/null
+++ b/net/ipv4/ip_output.c
@@ -0,0 +1,1359 @@
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		The Internet Protocol (IP) output module.
+ *
+ * Version:	$Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $
+ *
+ * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *		Donald Becker, <becker@super.org>
+ *		Alan Cox, <Alan.Cox@linux.org>
+ *		Richard Underwood
+ *		Stefan Becker, <stefanb@yello.ping.de>
+ *		Jorge Cwik, <jorge@laser.satlink.net>
+ *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
+ *		Hirokazu Takahashi, <taka@valinux.co.jp>
+ *
+ *	See ip_input.c for original log
+ *
+ *	Fixes:
+ *		Alan Cox	:	Missing nonblock feature in ip_build_xmit.
+ *		Mike Kilburn	:	htons() missing in ip_build_xmit.
+ *		Bradford Johnson:	Fix faulty handling of some frames when 
+ *					no route is found.
+ *		Alexander Demenshin:	Missing sk/skb free in ip_queue_xmit
+ *					(in case if packet not accepted by
+ *					output firewall rules)
+ *		Mike McLagan	:	Routing by source
+ *		Alexey Kuznetsov:	use new route cache
+ *		Andi Kleen:		Fix broken PMTU recovery and remove
+ *					some redundant tests.
+ *	Vitaly E. Lavrov	:	Transparent proxy revived after year coma.
+ *		Andi Kleen	: 	Replace ip_reply with ip_send_reply.
+ *		Andi Kleen	:	Split fast and slow ip_build_xmit path 
+ *					for decreased register pressure on x86 
+ *					and more readibility. 
+ *		Marc Boucher	:	When call_out_firewall returns FW_QUEUE,
+ *					silently drop skb instead of failing with -EPERM.
+ *		Detlev Wengorz	:	Copy protocol for fragments.
+ *		Hirokazu Takahashi:	HW checksumming for outgoing UDP
+ *					datagrams.
+ *		Hirokazu Takahashi:	sendfile() on UDP works now.
+ */
+
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/config.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/tcp.h>
+#include <net/udp.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/arp.h>
+#include <net/icmp.h>
+#include <net/raw.h>
+#include <net/checksum.h>
+#include <net/inetpeer.h>
+#include <net/checksum.h>
+#include <linux/igmp.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_bridge.h>
+#include <linux/mroute.h>
+#include <linux/netlink.h>
+
+/*
+ *      Shall we try to damage output packets if routing dev changes?
+ */
+
+int sysctl_ip_dynaddr;
+int sysctl_ip_default_ttl = IPDEFTTL;
+
+/* Generate a checksum for an outgoing IP datagram. */
+__inline__ void ip_send_check(struct iphdr *iph)
+{
+	iph->check = 0;
+	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
+}
+
+/* dev_loopback_xmit for use with netfilter. */
+static int ip_dev_loopback_xmit(struct sk_buff *newskb)
+{
+	newskb->mac.raw = newskb->data;
+	__skb_pull(newskb, newskb->nh.raw - newskb->data);
+	newskb->pkt_type = PACKET_LOOPBACK;
+	newskb->ip_summed = CHECKSUM_UNNECESSARY;
+	BUG_TRAP(newskb->dst);
+
+#ifdef CONFIG_NETFILTER_DEBUG
+	nf_debug_ip_loopback_xmit(newskb);
+#endif
+	netif_rx(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 = dst_metric(dst, RTAX_HOPLIMIT);
+	return ttl;
+}
+
+/* 
+ *		Add an ip header to a skbuff and send it out.
+ *
+ */
+int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
+			  u32 saddr, u32 daddr, struct ip_options *opt)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct rtable *rt = (struct rtable *)skb->dst;
+	struct iphdr *iph;
+
+	/* Build the IP header. */
+	if (opt)
+		iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen);
+	else
+		iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr));
+
+	iph->version  = 4;
+	iph->ihl      = 5;
+	iph->tos      = inet->tos;
+	if (ip_dont_fragment(sk, &rt->u.dst))
+		iph->frag_off = htons(IP_DF);
+	else
+		iph->frag_off = 0;
+	iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
+	iph->daddr    = rt->rt_dst;
+	iph->saddr    = rt->rt_src;
+	iph->protocol = sk->sk_protocol;
+	iph->tot_len  = htons(skb->len);
+	ip_select_ident(iph, &rt->u.dst, sk);
+	skb->nh.iph   = iph;
+
+	if (opt && opt->optlen) {
+		iph->ihl += opt->optlen>>2;
+		ip_options_build(skb, opt, daddr, rt, 0);
+	}
+	ip_send_check(iph);
+
+	skb->priority = sk->sk_priority;
+
+	/* Send it out. */
+	return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
+		       dst_output);
+}
+
+static inline int ip_finish_output2(struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb->dst;
+	struct hh_cache *hh = dst->hh;
+	struct net_device *dev = dst->dev;
+	int hh_len = LL_RESERVED_SPACE(dev);
+
+	/* Be paranoid, rather than too clever. */
+	if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
+		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;
+	}
+
+#ifdef CONFIG_NETFILTER_DEBUG
+	nf_debug_ip_finish_output2(skb);
+#endif /*CONFIG_NETFILTER_DEBUG*/
+
+	if (hh) {
+		int hh_alen;
+
+		read_lock_bh(&hh->hh_lock);
+		hh_alen = HH_DATA_ALIGN(hh->hh_len);
+  		memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
+		read_unlock_bh(&hh->hh_lock);
+	        skb_push(skb, hh->hh_len);
+		return hh->hh_output(skb);
+	} else if (dst->neighbour)
+		return dst->neighbour->output(skb);
+
+	if (net_ratelimit())
+		printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
+	kfree_skb(skb);
+	return -EINVAL;
+}
+
+int ip_finish_output(struct sk_buff *skb)
+{
+	struct net_device *dev = skb->dst->dev;
+
+	skb->dev = dev;
+	skb->protocol = htons(ETH_P_IP);
+
+	return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
+		       ip_finish_output2);
+}
+
+int ip_mc_output(struct sk_buff *skb)
+{
+	struct sock *sk = skb->sk;
+	struct rtable *rt = (struct rtable*)skb->dst;
+	struct net_device *dev = rt->u.dst.dev;
+
+	/*
+	 *	If the indicated interface is up and running, send the packet.
+	 */
+	IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
+
+	skb->dev = dev;
+	skb->protocol = htons(ETH_P_IP);
+
+	/*
+	 *	Multicasts are looped back for other local users
+	 */
+
+	if (rt->rt_flags&RTCF_MULTICAST) {
+		if ((!sk || inet_sk(sk)->mc_loop)
+#ifdef CONFIG_IP_MROUTE
+		/* Small optimization: do not loopback not local frames,
+		   which returned after forwarding; they will be  dropped
+		   by ip_mr_input in any case.
+		   Note, that local frames are looped back to be delivered
+		   to local recipients.
+
+		   This check is duplicated in ip_mr_input at the moment.
+		 */
+		    && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
+#endif
+		) {
+			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
+			if (newskb)
+				NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
+					newskb->dev, 
+					ip_dev_loopback_xmit);
+		}
+
+		/* Multicasts with ttl 0 must not go beyond the host */
+
+		if (skb->nh.iph->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(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
+				newskb->dev, ip_dev_loopback_xmit);
+	}
+
+	if (skb->len > dst_mtu(&rt->u.dst))
+		return ip_fragment(skb, ip_finish_output);
+	else
+		return ip_finish_output(skb);
+}
+
+int ip_output(struct sk_buff *skb)
+{
+	IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
+
+	if (skb->len > dst_mtu(skb->dst) && !skb_shinfo(skb)->tso_size)
+		return ip_fragment(skb, ip_finish_output);
+	else
+		return ip_finish_output(skb);
+}
+
+int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
+{
+	struct sock *sk = skb->sk;
+	struct inet_sock *inet = inet_sk(sk);
+	struct ip_options *opt = inet->opt;
+	struct rtable *rt;
+	struct iphdr *iph;
+
+	/* Skip all of this if the packet is already routed,
+	 * f.e. by something like SCTP.
+	 */
+	rt = (struct rtable *) skb->dst;
+	if (rt != NULL)
+		goto packet_routed;
+
+	/* Make sure we can route this packet. */
+	rt = (struct rtable *)__sk_dst_check(sk, 0);
+	if (rt == NULL) {
+		u32 daddr;
+
+		/* Use correct destination address if we have options. */
+		daddr = inet->daddr;
+		if(opt && opt->srr)
+			daddr = opt->faddr;
+
+		{
+			struct flowi fl = { .oif = sk->sk_bound_dev_if,
+					    .nl_u = { .ip4_u =
+						      { .daddr = daddr,
+							.saddr = inet->saddr,
+							.tos = RT_CONN_FLAGS(sk) } },
+					    .proto = sk->sk_protocol,
+					    .uli_u = { .ports =
+						       { .sport = inet->sport,
+							 .dport = inet->dport } } };
+
+			/* If this fails, retransmit mechanism of transport layer will
+			 * keep trying until route appears or the connection times
+			 * itself out.
+			 */
+			if (ip_route_output_flow(&rt, &fl, sk, 0))
+				goto no_route;
+		}
+		__sk_dst_set(sk, &rt->u.dst);
+		tcp_v4_setup_caps(sk, &rt->u.dst);
+	}
+	skb->dst = dst_clone(&rt->u.dst);
+
+packet_routed:
+	if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
+		goto no_route;
+
+	/* OK, we know where to send it, allocate and build IP header. */
+	iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
+	*((__u16 *)iph)	= htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
+	iph->tot_len = htons(skb->len);
+	if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
+		iph->frag_off = htons(IP_DF);
+	else
+		iph->frag_off = 0;
+	iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
+	iph->protocol = sk->sk_protocol;
+	iph->saddr    = rt->rt_src;
+	iph->daddr    = rt->rt_dst;
+	skb->nh.iph   = iph;
+	/* Transport layer set skb->h.foo itself. */
+
+	if (opt && opt->optlen) {
+		iph->ihl += opt->optlen >> 2;
+		ip_options_build(skb, opt, inet->daddr, rt, 0);
+	}
+
+	ip_select_ident_more(iph, &rt->u.dst, sk, skb_shinfo(skb)->tso_segs);
+
+	/* Add an IP checksum. */
+	ip_send_check(iph);
+
+	skb->priority = sk->sk_priority;
+
+	return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
+		       dst_output);
+
+no_route:
+	IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
+	kfree_skb(skb);
+	return -EHOSTUNREACH;
+}
+
+
+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;
+	to->security = from->security;
+	dst_release(to->dst);
+	to->dst = dst_clone(from->dst);
+	to->dev = from->dev;
+
+	/* Copy the flags to each fragment. */
+	IPCB(to)->flags = IPCB(from)->flags;
+
+#ifdef CONFIG_NET_SCHED
+	to->tc_index = from->tc_index;
+#endif
+#ifdef CONFIG_NETFILTER
+	to->nfmark = from->nfmark;
+	to->nfcache = from->nfcache;
+	/* Connection association is same as pre-frag packet */
+	nf_conntrack_put(to->nfct);
+	to->nfct = from->nfct;
+	nf_conntrack_get(to->nfct);
+	to->nfctinfo = from->nfctinfo;
+#ifdef CONFIG_BRIDGE_NETFILTER
+	nf_bridge_put(to->nf_bridge);
+	to->nf_bridge = from->nf_bridge;
+	nf_bridge_get(to->nf_bridge);
+#endif
+#ifdef CONFIG_NETFILTER_DEBUG
+	to->nf_debug = from->nf_debug;
+#endif
+#endif
+}
+
+/*
+ *	This IP datagram is too large to be sent in one piece.  Break it up into
+ *	smaller pieces (each of size equal to IP header plus
+ *	a block of the data of the original IP data part) that will yet fit in a
+ *	single device frame, and queue such a frame for sending.
+ */
+
+int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
+{
+	struct iphdr *iph;
+	int raw = 0;
+	int ptr;
+	struct net_device *dev;
+	struct sk_buff *skb2;
+	unsigned int mtu, hlen, left, len, ll_rs;
+	int offset;
+	int not_last_frag;
+	struct rtable *rt = (struct rtable*)skb->dst;
+	int err = 0;
+
+	dev = rt->u.dst.dev;
+
+	/*
+	 *	Point into the IP datagram header.
+	 */
+
+	iph = skb->nh.iph;
+
+	if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
+		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+			  htonl(dst_mtu(&rt->u.dst)));
+		kfree_skb(skb);
+		return -EMSGSIZE;
+	}
+
+	/*
+	 *	Setup starting values.
+	 */
+
+	hlen = iph->ihl * 4;
+	mtu = dst_mtu(&rt->u.dst) - hlen;	/* Size of data space */
+
+	/* When frag_list is given, use it. First, check its validity:
+	 * some transformers could create wrong frag_list or break existing
+	 * one, it is not prohibited. In this case fall back to copying.
+	 *
+	 * LATER: this step can be merged to real generation of fragments,
+	 * we can switch to copy when see the first bad fragment.
+	 */
+	if (skb_shinfo(skb)->frag_list) {
+		struct sk_buff *frag;
+		int first_len = skb_pagelen(skb);
+
+		if (first_len - hlen > mtu ||
+		    ((first_len - hlen) & 7) ||
+		    (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
+		    skb_cloned(skb))
+			goto slow_path;
+
+		for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
+			/* Correct geometry. */
+			if (frag->len > mtu ||
+			    ((frag->len & 7) && frag->next) ||
+			    skb_headroom(frag) < hlen)
+			    goto slow_path;
+
+			/* Partially cloned skb? */
+			if (skb_shared(frag))
+				goto slow_path;
+		}
+
+		/* Everything is OK. Generate! */
+
+		err = 0;
+		offset = 0;
+		frag = skb_shinfo(skb)->frag_list;
+		skb_shinfo(skb)->frag_list = NULL;
+		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 (;;) {
+			/* Prepare header of the next frame,
+			 * before previous one went down. */
+			if (frag) {
+				frag->ip_summed = CHECKSUM_NONE;
+				frag->h.raw = frag->data;
+				frag->nh.raw = __skb_push(frag, hlen);
+				memcpy(frag->nh.raw, iph, hlen);
+				iph = frag->nh.iph;
+				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);
+				/* Ready, complete checksum */
+				ip_send_check(iph);
+			}
+
+			err = output(skb);
+
+			if (err || !frag)
+				break;
+
+			skb = frag;
+			frag = skb->next;
+			skb->next = NULL;
+		}
+
+		if (err == 0) {
+			IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
+			return 0;
+		}
+
+		while (frag) {
+			skb = frag->next;
+			kfree_skb(frag);
+			frag = skb;
+		}
+		IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
+		return err;
+	}
+
+slow_path:
+	left = skb->len - hlen;		/* Space per frame */
+	ptr = raw + hlen;		/* Where to start from */
+
+#ifdef CONFIG_BRIDGE_NETFILTER
+	/* for bridged IP traffic encapsulated inside f.e. a vlan header,
+	 * we need to make room for the encapsulating header */
+	ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, nf_bridge_pad(skb));
+	mtu -= nf_bridge_pad(skb);
+#else
+	ll_rs = LL_RESERVED_SPACE(rt->u.dst.dev);
+#endif
+	/*
+	 *	Fragment the datagram.
+	 */
+
+	offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
+	not_last_frag = iph->frag_off & htons(IP_MF);
+
+	/*
+	 *	Keep copying data until we run out.
+	 */
+
+	while(left > 0)	{
+		len = left;
+		/* IF: it doesn't fit, use 'mtu' - the data space left */
+		if (len > mtu)
+			len = mtu;
+		/* IF: we are not sending upto and including the packet end
+		   then align the next start on an eight byte boundary */
+		if (len < left)	{
+			len &= ~7;
+		}
+		/*
+		 *	Allocate buffer.
+		 */
+
+		if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
+			NETDEBUG(printk(KERN_INFO "IP: frag: no memory for new fragment!\n"));
+			err = -ENOMEM;
+			goto fail;
+		}
+
+		/*
+		 *	Set up data on packet
+		 */
+
+		ip_copy_metadata(skb2, skb);
+		skb_reserve(skb2, ll_rs);
+		skb_put(skb2, len + hlen);
+		skb2->nh.raw = skb2->data;
+		skb2->h.raw = skb2->data + hlen;
+
+		/*
+		 *	Charge the memory for the fragment to any owner
+		 *	it might possess
+		 */
+
+		if (skb->sk)
+			skb_set_owner_w(skb2, skb->sk);
+
+		/*
+		 *	Copy the packet header into the new buffer.
+		 */
+
+		memcpy(skb2->nh.raw, skb->data, hlen);
+
+		/*
+		 *	Copy a block of the IP datagram.
+		 */
+		if (skb_copy_bits(skb, ptr, skb2->h.raw, len))
+			BUG();
+		left -= len;
+
+		/*
+		 *	Fill in the new header fields.
+		 */
+		iph = skb2->nh.iph;
+		iph->frag_off = htons((offset >> 3));
+
+		/* ANK: dirty, but effective trick. Upgrade options only if
+		 * the segment to be fragmented was THE FIRST (otherwise,
+		 * options are already fixed) and make it ONCE
+		 * on the initial skb, so that all the following fragments
+		 * will inherit fixed options.
+		 */
+		if (offset == 0)
+			ip_options_fragment(skb);
+
+		/*
+		 *	Added AC : If we are fragmenting a fragment that's not the
+		 *		   last fragment then keep MF on each bit
+		 */
+		if (left > 0 || not_last_frag)
+			iph->frag_off |= htons(IP_MF);
+		ptr += len;
+		offset += len;
+
+		/*
+		 *	Put this fragment into the sending queue.
+		 */
+
+		IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
+
+		iph->tot_len = htons(len + hlen);
+
+		ip_send_check(iph);
+
+		err = output(skb2);
+		if (err)
+			goto fail;
+	}
+	kfree_skb(skb);
+	IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
+	return err;
+
+fail:
+	kfree_skb(skb); 
+	IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
+	return err;
+}
+
+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_HW) {
+		if (memcpy_fromiovecend(to, iov, offset, len) < 0)
+			return -EFAULT;
+	} else {
+		unsigned int 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;
+}
+
+static inline unsigned int
+csum_page(struct page *page, int offset, int copy)
+{
+	char *kaddr;
+	unsigned int csum;
+	kaddr = kmap(page);
+	csum = csum_partial(kaddr + offset, copy, 0);
+	kunmap(page);
+	return csum;
+}
+
+/*
+ *	ip_append_data() and ip_append_page() can make one large IP datagram
+ *	from many pieces of data. Each pieces will be holded on the socket
+ *	until ip_push_pending_frames() is called. Each piece can be a page
+ *	or non-page data.
+ *	
+ *	Not only UDP, other transport protocols - e.g. raw sockets - can use
+ *	this interface potentially.
+ *
+ *	LATER: length must be adjusted by pad at tail, when it is required.
+ */
+int ip_append_data(struct sock *sk,
+		   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 *rt,
+		   unsigned int flags)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct sk_buff *skb;
+
+	struct ip_options *opt = NULL;
+	int hh_len;
+	int exthdrlen;
+	int mtu;
+	int copy;
+	int err;
+	int offset = 0;
+	unsigned int maxfraglen, fragheaderlen;
+	int csummode = CHECKSUM_NONE;
+
+	if (flags&MSG_PROBE)
+		return 0;
+
+	if (skb_queue_empty(&sk->sk_write_queue)) {
+		/*
+		 * setup for corking.
+		 */
+		opt = ipc->opt;
+		if (opt) {
+			if (inet->cork.opt == NULL) {
+				inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
+				if (unlikely(inet->cork.opt == NULL))
+					return -ENOBUFS;
+			}
+			memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
+			inet->cork.flags |= IPCORK_OPT;
+			inet->cork.addr = ipc->addr;
+		}
+		dst_hold(&rt->u.dst);
+		inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path);
+		inet->cork.rt = rt;
+		inet->cork.length = 0;
+		sk->sk_sndmsg_page = NULL;
+		sk->sk_sndmsg_off = 0;
+		if ((exthdrlen = rt->u.dst.header_len) != 0) {
+			length += exthdrlen;
+			transhdrlen += exthdrlen;
+		}
+	} else {
+		rt = inet->cork.rt;
+		if (inet->cork.flags & IPCORK_OPT)
+			opt = inet->cork.opt;
+
+		transhdrlen = 0;
+		exthdrlen = 0;
+		mtu = inet->cork.fragsize;
+	}
+	hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
+
+	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
+	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
+
+	if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
+		ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen);
+		return -EMSGSIZE;
+	}
+
+	/*
+	 * transhdrlen > 0 means that this is the first fragment and we wish
+	 * it won't be fragmented in the future.
+	 */
+	if (transhdrlen &&
+	    length + fragheaderlen <= mtu &&
+	    rt->u.dst.dev->features&(NETIF_F_IP_CSUM|NETIF_F_NO_CSUM|NETIF_F_HW_CSUM) &&
+	    !exthdrlen)
+		csummode = CHECKSUM_HW;
+
+	inet->cork.length += length;
+
+	/* So, what's going on in the loop below?
+	 *
+	 * We use calculated fragment length to generate chained skb,
+	 * each of segments is IP fragment ready for sending to network after
+	 * adding appropriate IP header.
+	 */
+
+	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
+		goto alloc_new_skb;
+
+	while (length > 0) {
+		/* Check if the remaining data fits into current packet. */
+		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;
+
+			/*
+			 * If remaining data exceeds the mtu,
+			 * we know we need more fragment(s).
+			 */
+			datalen = length + fraggap;
+			if (datalen > mtu - fragheaderlen)
+				datalen = maxfraglen - fragheaderlen;
+			fraglen = datalen + fragheaderlen;
+
+			if ((flags & MSG_MORE) && 
+			    !(rt->u.dst.dev->features&NETIF_F_SG))
+				alloclen = mtu;
+			else
+				alloclen = datalen + fragheaderlen;
+
+			/* The last fragment gets additional space at tail.
+			 * Note, with MSG_MORE we overallocate on fragments,
+			 * because we have no idea what fragment will be
+			 * the last.
+			 */
+			if (datalen == length)
+				alloclen += rt->u.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;
+			}
+			if (skb == NULL)
+				goto error;
+
+			/*
+			 *	Fill in the control structures
+			 */
+			skb->ip_summed = csummode;
+			skb->csum = 0;
+			skb_reserve(skb, hh_len);
+
+			/*
+			 *	Find where to start putting bytes.
+			 */
+			data = skb_put(skb, fraglen);
+			skb->nh.raw = data + exthdrlen;
+			data += fragheaderlen;
+			skb->h.raw = data + 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;
+				skb_trim(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;
+
+			/*
+			 * Put the packet on the pending queue.
+			 */
+			__skb_queue_tail(&sk->sk_write_queue, skb);
+			continue;
+		}
+
+		if (copy > length)
+			copy = length;
+
+		if (!(rt->u.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 = sk->sk_sndmsg_page;
+			int off = sk->sk_sndmsg_off;
+			unsigned int left;
+
+			if (page && (left = PAGE_SIZE - off) > 0) {
+				if (copy >= left)
+					copy = left;
+				if (page != frag->page) {
+					if (i == MAX_SKB_FRAGS) {
+						err = -EMSGSIZE;
+						goto error;
+					}
+					get_page(page);
+	 				skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
+					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;
+				}
+				sk->sk_sndmsg_page = page;
+				sk->sk_sndmsg_off = 0;
+
+				skb_fill_page_desc(skb, i, page, 0, 0);
+				frag = &skb_shinfo(skb)->frags[i];
+				skb->truesize += PAGE_SIZE;
+				atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
+			} else {
+				err = -EMSGSIZE;
+				goto error;
+			}
+			if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
+				err = -EFAULT;
+				goto error;
+			}
+			sk->sk_sndmsg_off += copy;
+			frag->size += copy;
+			skb->len += copy;
+			skb->data_len += copy;
+		}
+		offset += copy;
+		length -= copy;
+	}
+
+	return 0;
+
+error:
+	inet->cork.length -= length;
+	IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
+	return err; 
+}
+
+ssize_t	ip_append_page(struct sock *sk, 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;
+	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;
+
+	rt = inet->cork.rt;
+	if (inet->cork.flags & IPCORK_OPT)
+		opt = inet->cork.opt;
+
+	if (!(rt->u.dst.dev->features&NETIF_F_SG))
+		return -EOPNOTSUPP;
+
+	hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
+	mtu = inet->cork.fragsize;
+
+	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
+	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
+
+	if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
+		ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
+		return -EMSGSIZE;
+	}
+
+	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
+		return -EINVAL;
+
+	inet->cork.length += size;
+
+	while (size > 0) {
+		int i;
+
+		/* Check if the remaining data fits into current packet. */
+		len = mtu - skb->len;
+		if (len < size)
+			len = maxfraglen - skb->len;
+		if (len <= 0) {
+			struct sk_buff *skb_prev;
+			char *data;
+			struct iphdr *iph;
+			int alloclen;
+
+			skb_prev = skb;
+			if (skb_prev)
+				fraggap = skb_prev->len - maxfraglen;
+			else
+				fraggap = 0;
+
+			alloclen = fragheaderlen + hh_len + fraggap + 15;
+			skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
+			if (unlikely(!skb)) {
+				err = -ENOBUFS;
+				goto error;
+			}
+
+			/*
+			 *	Fill in the control structures
+			 */
+			skb->ip_summed = CHECKSUM_NONE;
+			skb->csum = 0;
+			skb_reserve(skb, hh_len);
+
+			/*
+			 *	Find where to start putting bytes.
+			 */
+			data = skb_put(skb, fragheaderlen + fraggap);
+			skb->nh.iph = iph = (struct iphdr *)data;
+			data += fragheaderlen;
+			skb->h.raw = data;
+
+			if (fraggap) {
+				skb->csum = skb_copy_and_csum_bits(
+					skb_prev, maxfraglen,
+					data, fraggap, 0);
+				skb_prev->csum = csum_sub(skb_prev->csum,
+							  skb->csum);
+				skb_trim(skb_prev, maxfraglen);
+			}
+
+			/*
+			 * Put the packet on the pending queue.
+			 */
+			__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_shinfo(skb)->frags[i-1].size += 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) {
+			unsigned int csum;
+			csum = csum_page(page, offset, len);
+			skb->csum = csum_block_add(skb->csum, csum, skb->len);
+		}
+
+		skb->len += len;
+		skb->data_len += len;
+		offset += len;
+		size -= len;
+	}
+	return 0;
+
+error:
+	inet->cork.length -= size;
+	IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
+	return err;
+}
+
+/*
+ *	Combined all pending IP fragments on the socket as one IP datagram
+ *	and push them out.
+ */
+int ip_push_pending_frames(struct sock *sk)
+{
+	struct sk_buff *skb, *tmp_skb;
+	struct sk_buff **tail_skb;
+	struct inet_sock *inet = inet_sk(sk);
+	struct ip_options *opt = NULL;
+	struct rtable *rt = inet->cork.rt;
+	struct iphdr *iph;
+	int df = 0;
+	__u8 ttl;
+	int err = 0;
+
+	if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
+		goto out;
+	tail_skb = &(skb_shinfo(skb)->frag_list);
+
+	/* move skb->data to ip header from ext header */
+	if (skb->data < skb->nh.raw)
+		__skb_pull(skb, skb->nh.raw - skb->data);
+	while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
+		__skb_pull(tmp_skb, skb->h.raw - skb->nh.raw);
+		*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;
+		__sock_put(tmp_skb->sk);
+		tmp_skb->destructor = NULL;
+		tmp_skb->sk = NULL;
+	}
+
+	/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
+	 * to fragment the frame generated here. No matter, what transforms
+	 * how transforms change size of the packet, it will come out.
+	 */
+	if (inet->pmtudisc != IP_PMTUDISC_DO)
+		skb->local_df = 1;
+
+	/* DF bit is set when we want to see DF on outgoing frames.
+	 * If local_df is set too, we still allow to fragment this frame
+	 * locally. */
+	if (inet->pmtudisc == IP_PMTUDISC_DO ||
+	    (skb->len <= dst_mtu(&rt->u.dst) &&
+	     ip_dont_fragment(sk, &rt->u.dst)))
+		df = htons(IP_DF);
+
+	if (inet->cork.flags & IPCORK_OPT)
+		opt = inet->cork.opt;
+
+	if (rt->rt_type == RTN_MULTICAST)
+		ttl = inet->mc_ttl;
+	else
+		ttl = ip_select_ttl(inet, &rt->u.dst);
+
+	iph = (struct iphdr *)skb->data;
+	iph->version = 4;
+	iph->ihl = 5;
+	if (opt) {
+		iph->ihl += opt->optlen>>2;
+		ip_options_build(skb, opt, inet->cork.addr, rt, 0);
+	}
+	iph->tos = inet->tos;
+	iph->tot_len = htons(skb->len);
+	iph->frag_off = df;
+	if (!df) {
+		__ip_select_ident(iph, &rt->u.dst, 0);
+	} else {
+		iph->id = htons(inet->id++);
+	}
+	iph->ttl = ttl;
+	iph->protocol = sk->sk_protocol;
+	iph->saddr = rt->rt_src;
+	iph->daddr = rt->rt_dst;
+	ip_send_check(iph);
+
+	skb->priority = sk->sk_priority;
+	skb->dst = dst_clone(&rt->u.dst);
+
+	/* Netfilter gets whole the not fragmented skb. */
+	err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, 
+		      skb->dst->dev, dst_output);
+	if (err) {
+		if (err > 0)
+			err = inet->recverr ? net_xmit_errno(err) : 0;
+		if (err)
+			goto error;
+	}
+
+out:
+	inet->cork.flags &= ~IPCORK_OPT;
+	if (inet->cork.opt) {
+		kfree(inet->cork.opt);
+		inet->cork.opt = NULL;
+	}
+	if (inet->cork.rt) {
+		ip_rt_put(inet->cork.rt);
+		inet->cork.rt = NULL;
+	}
+	return err;
+
+error:
+	IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
+	goto out;
+}
+
+/*
+ *	Throw away all pending data on the socket.
+ */
+void ip_flush_pending_frames(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct sk_buff *skb;
+
+	while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
+		kfree_skb(skb);
+
+	inet->cork.flags &= ~IPCORK_OPT;
+	if (inet->cork.opt) {
+		kfree(inet->cork.opt);
+		inet->cork.opt = NULL;
+	}
+	if (inet->cork.rt) {
+		ip_rt_put(inet->cork.rt);
+		inet->cork.rt = NULL;
+	}
+}
+
+
+/*
+ *	Fetch data from kernel space and fill in checksum if needed.
+ */
+static int ip_reply_glue_bits(void *dptr, char *to, int offset, 
+			      int len, int odd, struct sk_buff *skb)
+{
+	unsigned int csum;
+
+	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
+	skb->csum = csum_block_add(skb->csum, csum, odd);
+	return 0;  
+}
+
+/* 
+ *	Generic function to send a packet as reply to another packet.
+ *	Used to send TCP resets so far. ICMP should use this function too.
+ *
+ *	Should run single threaded per socket because it uses the sock 
+ *     	structure to pass arguments.
+ *
+ *	LATER: switch from ip_build_xmit to ip_append_*
+ */
+void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
+		   unsigned int len)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct {
+		struct ip_options	opt;
+		char			data[40];
+	} replyopts;
+	struct ipcm_cookie ipc;
+	u32 daddr;
+	struct rtable *rt = (struct rtable*)skb->dst;
+
+	if (ip_options_echo(&replyopts.opt, skb))
+		return;
+
+	daddr = ipc.addr = rt->rt_src;
+	ipc.opt = NULL;
+
+	if (replyopts.opt.optlen) {
+		ipc.opt = &replyopts.opt;
+
+		if (ipc.opt->srr)
+			daddr = replyopts.opt.faddr;
+	}
+
+	{
+		struct flowi fl = { .nl_u = { .ip4_u =
+					      { .daddr = daddr,
+						.saddr = rt->rt_spec_dst,
+						.tos = RT_TOS(skb->nh.iph->tos) } },
+				    /* Not quite clean, but right. */
+				    .uli_u = { .ports =
+					       { .sport = skb->h.th->dest,
+					         .dport = skb->h.th->source } },
+				    .proto = sk->sk_protocol };
+		if (ip_route_output_key(&rt, &fl))
+			return;
+	}
+
+	/* And let IP do all the hard work.
+
+	   This chunk is not reenterable, hence spinlock.
+	   Note that it uses the fact, that this function is called
+	   with locally disabled BH and that sk cannot be already spinlocked.
+	 */
+	bh_lock_sock(sk);
+	inet->tos = skb->nh.iph->tos;
+	sk->sk_priority = skb->priority;
+	sk->sk_protocol = skb->nh.iph->protocol;
+	ip_append_data(sk, 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)
+			*((u16 *)skb->h.raw + arg->csumoffset) = csum_fold(csum_add(skb->csum, arg->csum));
+		skb->ip_summed = CHECKSUM_NONE;
+		ip_push_pending_frames(sk);
+	}
+
+	bh_unlock_sock(sk);
+
+	ip_rt_put(rt);
+}
+
+/*
+ *	IP protocol layer initialiser
+ */
+
+static struct packet_type ip_packet_type = {
+	.type = __constant_htons(ETH_P_IP),
+	.func = ip_rcv,
+};
+
+/*
+ *	IP registers the packet type and then calls the subprotocol initialisers
+ */
+
+void __init ip_init(void)
+{
+	dev_add_pack(&ip_packet_type);
+
+	ip_rt_init();
+	inet_initpeers();
+
+#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
+	igmp_mc_proc_init();
+#endif
+}
+
+EXPORT_SYMBOL(ip_finish_output);
+EXPORT_SYMBOL(ip_fragment);
+EXPORT_SYMBOL(ip_generic_getfrag);
+EXPORT_SYMBOL(ip_queue_xmit);
+EXPORT_SYMBOL(ip_send_check);
+
+#ifdef CONFIG_SYSCTL
+EXPORT_SYMBOL(sysctl_ip_default_ttl);
+#endif