C++ icmpv6_send函数代码示例

int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
	     struct ipv6_txoptions *opt)
{
	struct net *net = sock_net(sk);
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct in6_addr *first_hop = &fl6->daddr;
	struct dst_entry *dst = skb_dst(skb);
	struct ipv6hdr *hdr;
	u8  proto = fl6->flowi6_proto;
	int seg_len = skb->len;
	int hlimit = -1;
	int tclass = 0;
	u32 mtu;

	if (opt) {
		unsigned int head_room;

		/* First: exthdrs may take lots of space (~8K for now)
		   MAX_HEADER is not enough.
		 */
		head_room = opt->opt_nflen + opt->opt_flen;
		seg_len += head_room;
		head_room += sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dst->dev);

		if (skb_headroom(skb) < head_room) {
			struct sk_buff *skb2 = skb_realloc_headroom(skb, head_room);
			if (skb2 == NULL) {
				IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
					      IPSTATS_MIB_OUTDISCARDS);
				kfree_skb(skb);
				return -ENOBUFS;
			}
			kfree_skb(skb);
			skb = skb2;
			skb_set_owner_w(skb, sk);
		}
		if (opt->opt_flen)
			ipv6_push_frag_opts(skb, opt, &proto);
		if (opt->opt_nflen)
			ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop);
	}

	skb_push(skb, sizeof(struct ipv6hdr));
	skb_reset_network_header(skb);
	hdr = ipv6_hdr(skb);

	/*
	 *	Fill in the IPv6 header
	 */
	if (np) {
		tclass = np->tclass;
		hlimit = np->hop_limit;
	}
	if (hlimit < 0)
		hlimit = ip6_dst_hoplimit(dst);

	*(__be32 *)hdr = htonl(0x60000000 | (tclass << 20)) | fl6->flowlabel;

	hdr->payload_len = htons(seg_len);
	hdr->nexthdr = proto;
	hdr->hop_limit = hlimit;

	ipv6_addr_copy(&hdr->saddr, &fl6->saddr);
	ipv6_addr_copy(&hdr->daddr, first_hop);

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

	mtu = dst_mtu(dst);
	if ((skb->len <= mtu) || skb->local_df || skb_is_gso(skb)) {
		IP6_UPD_PO_STATS(net, ip6_dst_idev(skb_dst(skb)),
			      IPSTATS_MIB_OUT, skb->len);
		return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL,
			       dst->dev, dst_output);
	}

	if (net_ratelimit())
		printk(KERN_DEBUG "IPv6: sending pkt_too_big to self\n");
	skb->dev = dst->dev;
	icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_FRAGFAILS);
	kfree_skb(skb);
	return -EMSGSIZE;
}

int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
{
	struct sk_buff *frag;
	struct rt6_info *rt = (struct rt6_info*)skb_dst(skb);
	struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
	struct ipv6hdr *tmp_hdr;
	struct frag_hdr *fh;
	unsigned int mtu, hlen, left, len;
	__be32 frag_id = 0;
	int ptr, offset = 0, err=0;
	u8 *prevhdr, nexthdr = 0;
	struct net *net = dev_net(skb_dst(skb)->dev);

	hlen = ip6_find_1stfragopt(skb, &prevhdr);
	nexthdr = *prevhdr;

	mtu = ip6_skb_dst_mtu(skb);

	/* We must not fragment if the socket is set to force MTU discovery
	 * or if the skb it not generated by a local socket.
	 */
	if (!skb->local_df && skb->len > mtu) {
		skb->dev = skb_dst(skb)->dev;
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
			      IPSTATS_MIB_FRAGFAILS);
		kfree_skb(skb);
		return -EMSGSIZE;
	}

	if (np && np->frag_size < mtu) {
		if (np->frag_size)
			mtu = np->frag_size;
	}
	mtu -= hlen + sizeof(struct frag_hdr);

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

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

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

			/* Partially cloned skb? */
			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);
		/* BUILD HEADER */

		*prevhdr = NEXTHDR_FRAGMENT;
		tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
		if (!tmp_hdr) {
			IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
				      IPSTATS_MIB_FRAGFAILS);
			return -ENOMEM;
		}

		__skb_pull(skb, hlen);
		fh = (struct frag_hdr*)__skb_push(skb, sizeof(struct frag_hdr));
		__skb_push(skb, hlen);
		skb_reset_network_header(skb);
		memcpy(skb_network_header(skb), tmp_hdr, hlen);

		ipv6_select_ident(fh, &rt->rt6i_dst.addr);
		fh->nexthdr = nexthdr;
		fh->reserved = 0;
		fh->frag_off = htons(IP6_MF);
		frag_id = fh->identification;

		first_len = skb_pagelen(skb);
		skb->data_len = first_len - skb_headlen(skb);
		skb->len = first_len;
		ipv6_hdr(skb)->payload_len = htons(first_len -
						   sizeof(struct ipv6hdr));

		dst_hold(&rt->dst);

		for (;;) {
			/* Prepare header of the next frame,
//.........这里部分代码省略.........

/* <DTS2012022805249  g00206962 2012/2/27 add begin */
static inline int ip6_input_icmp_cheat(struct sk_buff *skb)
{
	struct inet6_protocol *ipprot;
	unsigned int nhoff;
	int nexthdr, raw;
	u8 hash;
	struct inet6_dev *idev;
	struct net *net = dev_net(skb->dst->dev);

	/*
	 *	Parse extension headers
	 */

	rcu_read_lock();
resubmit:
	idev = ip6_dst_idev(skb->dst);
	if (!pskb_pull(skb, skb_transport_offset(skb)))
		goto discard;
	nhoff = IP6CB(skb)->nhoff;
	nexthdr = skb_network_header(skb)[nhoff];

	raw = raw6_local_deliver(skb, nexthdr);

	hash = nexthdr & (MAX_INET_PROTOS - 1);
	if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
		int ret;

		if (ipprot->flags & INET6_PROTO_FINAL) {
			struct ipv6hdr *hdr;

			/* Free reference early: we don't need it any more,
			   and it may hold ip_conntrack module loaded
			   indefinitely. */
			nf_reset(skb);

			skb_postpull_rcsum(skb, skb_network_header(skb),
					   skb_network_header_len(skb));
			hdr = ipv6_hdr(skb);
            /*
			if (ipv6_addr_is_multicast(&hdr->daddr) &&
			    !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
			    &hdr->saddr) &&
			    !ipv6_is_mld(skb, nexthdr))
				goto discard;
			*/
			if (ipv6_addr_is_multicast(&hdr->daddr) && IPPROTO_ICMPV6 != nexthdr)
				goto discard;
			else if (!ipv6_addr_is_multicast(&hdr->daddr))
				goto discard;
		}
		if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
		    !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
			goto discard;

		ret = ipprot->handler(skb);
		if (ret > 0)
			goto resubmit;
		else if (ret == 0)
			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
	} else {
		if (!raw) {
			if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
				IP6_INC_STATS_BH(net, idev,
						 IPSTATS_MIB_INUNKNOWNPROTOS);
				icmpv6_send(skb, ICMPV6_PARAMPROB,
					    ICMPV6_UNK_NEXTHDR, nhoff,
					    skb->dev);
			}
		} else
			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
		kfree_skb(skb);
	}
	rcu_read_unlock();
	return 0;

discard:
	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
	rcu_read_unlock();
	kfree_skb(skb);
	return 0;
}

static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
{
	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
}

static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct ip_tunnel *tunnel = netdev_priv(dev);
	struct net_device_stats *stats = &tunnel->stat;
	struct iphdr  *tiph = &tunnel->parms.iph;
	struct ipv6hdr *iph6 = ipv6_hdr(skb);
	u8     tos = tunnel->parms.iph.tos;
	struct rtable *rt;     			/* Route to the other host */
	struct net_device *tdev;			/* Device to other host */
	struct iphdr  *iph;			/* Our new IP header */
	unsigned int max_headroom;		/* The extra header space needed */
	__be32 dst = tiph->daddr;
	int    mtu;

	if (tunnel->recursion++) {
		tunnel->stat.collisions++;
		goto tx_error;
	}

	if (skb->protocol != htons(ETH_P_IPV6))
		goto tx_error;

	if (extract_ipv4_endpoint(&iph6->daddr, &dst) < 0)
		goto tx_error_icmp;

	{
		struct flowi fl = { .nl_u = { .ip4_u =
					      { .daddr = dst,
						.saddr = tiph->saddr,
						.tos = RT_TOS(tos) } },
				    .oif = tunnel->parms.link,
				    .proto = IPPROTO_IPV6 };
		if (ip_route_output_key(&rt, &fl)) {
			tunnel->stat.tx_carrier_errors++;
			goto tx_error_icmp;
		}
	}
	if (rt->rt_type != RTN_UNICAST) {
		ip_rt_put(rt);
		tunnel->stat.tx_carrier_errors++;
		goto tx_error_icmp;
	}
	tdev = rt->u.dst.dev;

	if (tdev == dev) {
		ip_rt_put(rt);
		tunnel->stat.collisions++;
		goto tx_error;
	}

	if (tiph->frag_off)
		mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
	else
		mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;

	if (mtu < 68) {
		tunnel->stat.collisions++;
		ip_rt_put(rt);
		goto tx_error;
	}
	if (mtu < IPV6_MIN_MTU)
		mtu = IPV6_MIN_MTU;
	if (tunnel->parms.iph.daddr && skb->dst)
		skb->dst->ops->update_pmtu(skb->dst, mtu);

	if (skb->len > mtu) {
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
		ip_rt_put(rt);
		goto tx_error;
	}

	if (tunnel->err_count > 0) {
		if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
			tunnel->err_count--;
			dst_link_failure(skb);
		} else
			tunnel->err_count = 0;
	}

	/*
	 * Okay, now see if we can stuff it in the buffer as-is.
	 */
	max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);

	if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
	    (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
		struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
		if (!new_skb) {
			ip_rt_put(rt);
			stats->tx_dropped++;
			dev_kfree_skb(skb);
			tunnel->recursion--;
			return 0;
		}
		if (skb->sk)
			skb_set_owner_w(new_skb, skb->sk);
		dev_kfree_skb(skb);
		skb = new_skb;
		iph6 = ipv6_hdr(skb);
	}
//.........这里部分代码省略.........

int
ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
		 struct ip_vs_protocol *pp)
{
	struct rt6_info *rt;			/* Route to the other host */
	int    mtu;

	EnterFunction(10);

	if (!(rt = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL,
					 0, (IP_VS_RT_MODE_LOCAL |
					     IP_VS_RT_MODE_NON_LOCAL))))
		goto tx_error_icmp;
	if (__ip_vs_is_local_route6(rt)) {
		dst_release(&rt->dst);
		IP_VS_XMIT(NFPROTO_IPV6, skb, cp, 1);
	}

	/* MTU checking */
	mtu = dst_mtu(&rt->dst);
	if (skb->len > mtu) {
		if (!skb->dev) {
			struct net *net = dev_net(skb_dst(skb)->dev);

			skb->dev = net->loopback_dev;
		}
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		dst_release(&rt->dst);
		IP_VS_DBG_RL("%s(): frag needed\n", __func__);
		goto tx_error;
	}

	/*
	 * Call ip_send_check because we are not sure it is called
	 * after ip_defrag. Is copy-on-write needed?
	 */
	skb = skb_share_check(skb, GFP_ATOMIC);
	if (unlikely(skb == NULL)) {
		dst_release(&rt->dst);
		return NF_STOLEN;
	}

	/* drop old route */
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);

	/* Another hack: avoid icmp_send in ip_fragment */
	skb->local_df = 1;

	IP_VS_XMIT(NFPROTO_IPV6, skb, cp, 0);

	LeaveFunction(10);
	return NF_STOLEN;

tx_error_icmp:
	dst_link_failure(skb);
tx_error:
	kfree_skb(skb);
	LeaveFunction(10);
	return NF_STOLEN;
}

int
ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
		struct ip_vs_protocol *pp, int offset, unsigned int hooknum)
{
	struct rt6_info	*rt;	/* Route to the other host */
	int mtu;
	int rc;
	int local;
	int rt_mode;

	EnterFunction(10);

	/* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be
	   forwarded directly here, because there is no need to
	   translate address/port back */
	if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) {
		if (cp->packet_xmit)
			rc = cp->packet_xmit(skb, cp, pp);
		else
			rc = NF_ACCEPT;
		/* do not touch skb anymore */
		atomic_inc(&cp->in_pkts);
		goto out;
	}

	/*
	 * mangle and send the packet here (only for VS/NAT)
	 */

	/* LOCALNODE from FORWARD hook is not supported */
	rt_mode = (hooknum != NF_INET_FORWARD) ?
		  IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL |
		  IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL;
	if (!(rt = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL,
					 0, rt_mode)))
		goto tx_error_icmp;

	local = __ip_vs_is_local_route6(rt);
	/*
	 * Avoid duplicate tuple in reply direction for NAT traffic
	 * to local address when connection is sync-ed
	 */
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
	if (cp->flags & IP_VS_CONN_F_SYNC && local) {
		enum ip_conntrack_info ctinfo;
		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);

		if (ct && !nf_ct_is_untracked(ct)) {
			IP_VS_DBG(10, "%s(): "
				  "stopping DNAT to local address %pI6\n",
				  __func__, &cp->daddr.in6);
			goto tx_error_put;
		}
	}
#endif

	/* From world but DNAT to loopback address? */
	if (local && skb->dev && !(skb->dev->flags & IFF_LOOPBACK) &&
	    ipv6_addr_type(&rt->rt6i_dst.addr) & IPV6_ADDR_LOOPBACK) {
		IP_VS_DBG(1, "%s(): "
			  "stopping DNAT to loopback %pI6\n",
			  __func__, &cp->daddr.in6);
		goto tx_error_put;
	}

	/* MTU checking */
	mtu = dst_mtu(&rt->dst);
	if (skb->len > mtu && !skb_is_gso(skb)) {
		if (!skb->dev) {
			struct net *net = dev_net(skb_dst(skb)->dev);

			skb->dev = net->loopback_dev;
		}
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		IP_VS_DBG_RL("%s(): frag needed\n", __func__);
		goto tx_error_put;
	}

	/* copy-on-write the packet before mangling it */
	if (!skb_make_writable(skb, offset))
		goto tx_error_put;

	if (skb_cow(skb, rt->dst.dev->hard_header_len))
		goto tx_error_put;

	ip_vs_nat_icmp_v6(skb, pp, cp, 0);

	if (!local || !skb->dev) {
		/* drop the old route when skb is not shared */
		skb_dst_drop(skb);
		skb_dst_set(skb, &rt->dst);
	} else {
		/* destined to loopback, do we need to change route? */
		dst_release(&rt->dst);
	}

	/* Another hack: avoid icmp_send in ip_fragment */
	skb->local_df = 1;

	IP_VS_XMIT_NAT(NFPROTO_IPV6, skb, cp, local);
//.........这里部分代码省略.........

static int
ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct ip6_tnl *t = netdev_priv(dev);
	struct net_device_stats *stats = &t->stat;
	struct ipv6hdr *ipv6h = skb->nh.ipv6h;
	int encap_limit = -1;
	struct ipv6_tel_txoption opt;
	__u16 offset;
	struct flowi fl;
	struct dst_entry *dst;
	struct net_device *tdev;
	int mtu;
	int max_headroom = sizeof(struct ipv6hdr);
	u8 proto;
	int err;
	int pkt_len;
	int dsfield;

	if (t->recursion++) {
		stats->collisions++;
		goto tx_err;
	}
	if (skb->protocol != htons(ETH_P_IPV6) ||
	    !ip6_tnl_xmit_ctl(t) || ip6ip6_tnl_addr_conflict(t, ipv6h))
		goto tx_err;

	if ((offset = parse_tlv_tnl_enc_lim(skb, skb->nh.raw)) > 0) {
		struct ipv6_tlv_tnl_enc_lim *tel;
		tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->nh.raw[offset];
		if (tel->encap_limit == 0) {
			icmpv6_send(skb, ICMPV6_PARAMPROB,
				    ICMPV6_HDR_FIELD, offset + 2, skb->dev);
			goto tx_err;
		}
		encap_limit = tel->encap_limit - 1;
	} else if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
		encap_limit = t->parms.encap_limit;

	memcpy(&fl, &t->fl, sizeof (fl));
	proto = fl.proto;

	dsfield = ipv6_get_dsfield(ipv6h);
	if ((t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS))
		fl.fl6_flowlabel |= (*(__be32 *) ipv6h & IPV6_TCLASS_MASK);
	if ((t->parms.flags & IP6_TNL_F_USE_ORIG_FLOWLABEL))
		fl.fl6_flowlabel |= (*(__be32 *) ipv6h & IPV6_FLOWLABEL_MASK);

	if ((dst = ip6_tnl_dst_check(t)) != NULL)
		dst_hold(dst);
	else {
		dst = ip6_route_output(NULL, &fl);

		if (dst->error || xfrm_lookup(&dst, &fl, NULL, 0) < 0)
			goto tx_err_link_failure;
	}

	tdev = dst->dev;

	if (tdev == dev) {
		stats->collisions++;
		if (net_ratelimit())
			printk(KERN_WARNING
			       "%s: Local routing loop detected!\n",
			       t->parms.name);
		goto tx_err_dst_release;
	}
	mtu = dst_mtu(dst) - sizeof (*ipv6h);
	if (encap_limit >= 0) {
		max_headroom += 8;
		mtu -= 8;
	}
	if (mtu < IPV6_MIN_MTU)
		mtu = IPV6_MIN_MTU;
	if (skb->dst)
		skb->dst->ops->update_pmtu(skb->dst, mtu);
	if (skb->len > mtu) {
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
		goto tx_err_dst_release;
	}

	/*
	 * Okay, now see if we can stuff it in the buffer as-is.
	 */
	max_headroom += LL_RESERVED_SPACE(tdev);

	if (skb_headroom(skb) < max_headroom ||
	    skb_cloned(skb) || skb_shared(skb)) {
		struct sk_buff *new_skb;

		if (!(new_skb = skb_realloc_headroom(skb, max_headroom)))
			goto tx_err_dst_release;

		if (skb->sk)
			skb_set_owner_w(new_skb, skb->sk);
		kfree_skb(skb);
		skb = new_skb;
	}
	dst_release(skb->dst);
	skb->dst = dst_clone(dst);
//.........这里部分代码省略.........

static int
ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
	   int type, int code, int offset, __be32 info)
{
	struct ipv6hdr *ipv6h = (struct ipv6hdr *) skb->data;
	struct ip6_tnl *t;
	int rel_msg = 0;
	int rel_type = ICMPV6_DEST_UNREACH;
	int rel_code = ICMPV6_ADDR_UNREACH;
	__u32 rel_info = 0;
	__u16 len;
	int err = -ENOENT;

	/* If the packet doesn't contain the original IPv6 header we are
	   in trouble since we might need the source address for further
	   processing of the error. */

	read_lock(&ip6ip6_lock);
	if ((t = ip6ip6_tnl_lookup(&ipv6h->daddr, &ipv6h->saddr)) == NULL)
		goto out;

	err = 0;

	switch (type) {
		__u32 teli;
		struct ipv6_tlv_tnl_enc_lim *tel;
		__u32 mtu;
	case ICMPV6_DEST_UNREACH:
		if (net_ratelimit())
			printk(KERN_WARNING
			       "%s: Path to destination invalid "
			       "or inactive!\n", t->parms.name);
		rel_msg = 1;
		break;
	case ICMPV6_TIME_EXCEED:
		if (code == ICMPV6_EXC_HOPLIMIT) {
			if (net_ratelimit())
				printk(KERN_WARNING
				       "%s: Too small hop limit or "
				       "routing loop in tunnel!\n",
				       t->parms.name);
			rel_msg = 1;
		}
		break;
	case ICMPV6_PARAMPROB:
		teli = 0;
		if (code == ICMPV6_HDR_FIELD)
			teli = parse_tlv_tnl_enc_lim(skb, skb->data);

		if (teli && teli == ntohl(info) - 2) {
			tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->data[teli];
			if (tel->encap_limit == 0) {
				if (net_ratelimit())
					printk(KERN_WARNING
					       "%s: Too small encapsulation "
					       "limit or routing loop in "
					       "tunnel!\n", t->parms.name);
				rel_msg = 1;
			}
		} else if (net_ratelimit()) {
			printk(KERN_WARNING
			       "%s: Recipient unable to parse tunneled "
			       "packet!\n ", t->parms.name);
		}
		break;
	case ICMPV6_PKT_TOOBIG:
		mtu = ntohl(info) - offset;
		if (mtu < IPV6_MIN_MTU)
			mtu = IPV6_MIN_MTU;
		t->dev->mtu = mtu;

		if ((len = sizeof (*ipv6h) + ntohs(ipv6h->payload_len)) > mtu) {
			rel_type = ICMPV6_PKT_TOOBIG;
			rel_code = 0;
			rel_info = mtu;
			rel_msg = 1;
		}
		break;
	}
	if (rel_msg &&  pskb_may_pull(skb, offset + sizeof (*ipv6h))) {
		struct rt6_info *rt;
		struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

		if (!skb2)
			goto out;

		dst_release(skb2->dst);
		skb2->dst = NULL;
		skb_pull(skb2, offset);
		skb2->nh.raw = skb2->data;

		/* Try to guess incoming interface */
		rt = rt6_lookup(&skb2->nh.ipv6h->saddr, NULL, 0, 0);

		if (rt && rt->rt6i_dev)
			skb2->dev = rt->rt6i_dev;

		icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev);

		if (rt)
//.........这里部分代码省略.........

bool determine_in_tuple(struct sk_buff *skb, struct tuple *tuple)
{
	struct iphdr *hdr4;
	struct ipv6hdr *hdr6;
	struct icmphdr *icmp4;
	struct icmp6hdr *icmp6;
	struct hdr_iterator iterator;

	log_debug("Step 1: Determining the Incoming Tuple");

	switch (be16_to_cpu(skb->protocol)) {
	case ETH_P_IP:
		hdr4 = ip_hdr(skb);
		switch (hdr4->protocol) {
		case IPPROTO_UDP:
			if (!ipv4_udp(hdr4, ipv4_extract_l4_hdr(hdr4), tuple))
				return false;
			break;
		case IPPROTO_TCP:
			if (!ipv4_tcp(hdr4, ipv4_extract_l4_hdr(hdr4), tuple))
				return false;
			break;
		case IPPROTO_ICMP:
			icmp4 = ipv4_extract_l4_hdr(hdr4);
			if (is_icmp4_info(icmp4->type)) {
				if (!ipv4_icmp_info(hdr4, icmp4, tuple))
					return false;
			} else {
				if (!ipv4_icmp_err(hdr4, icmp4, tuple))
					return false;
			}
			break;
		default:
			log_info("Unsupported transport protocol for IPv4: %d.", hdr4->protocol);
			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
			return false;
		}
		break;

	case ETH_P_IPV6:
		hdr6 = ipv6_hdr(skb);
		hdr_iterator_init(&iterator, hdr6);
		hdr_iterator_last(&iterator);
		switch (iterator.hdr_type) {
		case IPPROTO_UDP:
			if (!ipv6_udp(hdr6, iterator.data, tuple))
				return false;
			break;
		case IPPROTO_TCP:
			if (!ipv6_tcp(hdr6, iterator.data, tuple))
				return false;
			break;
		case IPPROTO_ICMPV6:
			icmp6 = iterator.data;
			if (is_icmp6_info(icmp6->icmp6_type)) {
				if (!ipv6_icmp_info(hdr6, icmp6, tuple))
					return false;
			} else {
				if (!ipv6_icmp_err(hdr6, icmp6, tuple))
					return false;
			}
			break;
		default:
			log_info("Unsupported transport protocol for IPv6: %d.", iterator.hdr_type);
			icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
			return false;
		}
		break;

	default:
		log_info("Packet's protocol (%d) is not IPv4 or IPv6.", be16_to_cpu(skb->protocol));
		return false;
	}

	log_tuple(tuple);
	log_debug("Done step 1.");
	return true;
}

static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
			    struct flowi *fl)
{
	struct ip_tunnel *tunnel = netdev_priv(dev);
	struct ip_tunnel_parm *parms = &tunnel->parms;
	struct dst_entry *dst = skb_dst(skb);
	struct net_device *tdev;	/* Device to other host */
	int err;
	int mtu;

	if (!dst) {
		dev->stats.tx_carrier_errors++;
		goto tx_error_icmp;
	}

	dst_hold(dst);
	dst = xfrm_lookup(tunnel->net, dst, fl, NULL, 0);
	if (IS_ERR(dst)) {
		dev->stats.tx_carrier_errors++;
		goto tx_error_icmp;
	}

	if (!vti_state_check(dst->xfrm, parms->iph.daddr, parms->iph.saddr)) {
		dev->stats.tx_carrier_errors++;
		dst_release(dst);
		goto tx_error_icmp;
	}

	tdev = dst->dev;

	if (tdev == dev) {
		dst_release(dst);
		dev->stats.collisions++;
		goto tx_error;
	}

	if (tunnel->err_count > 0) {
		if (time_before(jiffies,
				tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
			tunnel->err_count--;
			dst_link_failure(skb);
		} else
			tunnel->err_count = 0;
	}

	mtu = dst_mtu(dst);
	if (skb->len > mtu) {
		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
		if (skb->protocol == htons(ETH_P_IP)) {
			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
				  htonl(mtu));
		} else {
			if (mtu < IPV6_MIN_MTU)
				mtu = IPV6_MIN_MTU;

			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		}

		dst_release(dst);
		goto tx_error;
	}

	skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(dev)));
	skb_dst_set(skb, dst);
	skb->dev = skb_dst(skb)->dev;

	err = dst_output(tunnel->net, skb->sk, skb);
	if (net_xmit_eval(err) == 0)
		err = skb->len;
	iptunnel_xmit_stats(dev, err);
	return NETDEV_TX_OK;

tx_error_icmp:
	dst_link_failure(skb);
tx_error:
	dev->stats.tx_errors++;
	kfree_skb(skb);
	return NETDEV_TX_OK;
}

int
ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
		  struct ip_vs_protocol *pp)
{
	struct rt6_info *rt;		/* Route to the other host */
	int mtu;
	int local;

	EnterFunction(10);

	/* check if it is a connection of no-client-port */
	if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) {
		__be16 _pt, *p;
		p = skb_header_pointer(skb, sizeof(struct ipv6hdr),
				       sizeof(_pt), &_pt);
		if (p == NULL)
			goto tx_error;
		ip_vs_conn_fill_cport(cp, *p);
		IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p));
	}

	if (!(rt = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL,
					 0, (IP_VS_RT_MODE_LOCAL |
					     IP_VS_RT_MODE_NON_LOCAL |
					     IP_VS_RT_MODE_RDR))))
		goto tx_error_icmp;
	local = __ip_vs_is_local_route6(rt);
	/*
	 * Avoid duplicate tuple in reply direction for NAT traffic
	 * to local address when connection is sync-ed
	 */
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
	if (cp->flags & IP_VS_CONN_F_SYNC && local) {
		enum ip_conntrack_info ctinfo;
		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);

		if (ct && !nf_ct_is_untracked(ct)) {
			IP_VS_DBG_RL_PKT(10, AF_INET6, pp, skb, 0,
					 "ip_vs_nat_xmit_v6(): "
					 "stopping DNAT to local address");
			goto tx_error_put;
		}
	}
#endif

	/* From world but DNAT to loopback address? */
	if (local && skb->dev && !(skb->dev->flags & IFF_LOOPBACK) &&
	    ipv6_addr_type(&rt->rt6i_dst.addr) & IPV6_ADDR_LOOPBACK) {
		IP_VS_DBG_RL_PKT(1, AF_INET6, pp, skb, 0,
				 "ip_vs_nat_xmit_v6(): "
				 "stopping DNAT to loopback address");
		goto tx_error_put;
	}

	/* MTU checking */
	mtu = dst_mtu(&rt->dst);
	if (skb->len > mtu && !skb_is_gso(skb)) {
		if (!skb->dev) {
			struct net *net = dev_net(skb_dst(skb)->dev);

			skb->dev = net->loopback_dev;
		}
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		IP_VS_DBG_RL_PKT(0, AF_INET6, pp, skb, 0,
				 "ip_vs_nat_xmit_v6(): frag needed for");
		goto tx_error_put;
	}

	/* copy-on-write the packet before mangling it */
	if (!skb_make_writable(skb, sizeof(struct ipv6hdr)))
		goto tx_error_put;

	if (skb_cow(skb, rt->dst.dev->hard_header_len))
		goto tx_error_put;

	/* mangle the packet */
	if (pp->dnat_handler && !pp->dnat_handler(skb, pp, cp))
		goto tx_error;
	ipv6_hdr(skb)->daddr = cp->daddr.in6;

	if (!local || !skb->dev) {
		/* drop the old route when skb is not shared */
		skb_dst_drop(skb);
		skb_dst_set(skb, &rt->dst);
	} else {
		/* destined to loopback, do we need to change route? */
		dst_release(&rt->dst);
	}

	IP_VS_DBG_PKT(10, AF_INET6, pp, skb, 0, "After DNAT");

	/* FIXME: when application helper enlarges the packet and the length
	   is larger than the MTU of outgoing device, there will be still
	   MTU problem. */

	/* Another hack: avoid icmp_send in ip_fragment */
	skb->local_df = 1;

	IP_VS_XMIT_NAT(NFPROTO_IPV6, skb, cp, local);

//.........这里部分代码省略.........

int
ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
		     struct ip_vs_protocol *pp)
{
	struct rt6_info *rt;		/* Route to the other host */
	struct in6_addr saddr;		/* Source for tunnel */
	struct net_device *tdev;	/* Device to other host */
	struct ipv6hdr  *old_iph = ipv6_hdr(skb);
	struct ipv6hdr  *iph;		/* Our new IP header */
	unsigned int max_headroom;	/* The extra header space needed */
	int    mtu;
	int ret;

	EnterFunction(10);

	if (!(rt = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6,
					 &saddr, 1, (IP_VS_RT_MODE_LOCAL |
						     IP_VS_RT_MODE_NON_LOCAL))))
		goto tx_error_icmp;
	if (__ip_vs_is_local_route6(rt)) {
		dst_release(&rt->dst);
		IP_VS_XMIT(NFPROTO_IPV6, skb, cp, 1);
	}

	tdev = rt->dst.dev;

	mtu = dst_mtu(&rt->dst) - sizeof(struct ipv6hdr);
	if (mtu < IPV6_MIN_MTU) {
		IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
			     IPV6_MIN_MTU);
		goto tx_error_put;
	}
	if (skb_dst(skb))
		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);

	if (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) &&
	    !skb_is_gso(skb)) {
		if (!skb->dev) {
			struct net *net = dev_net(skb_dst(skb)->dev);

			skb->dev = net->loopback_dev;
		}
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		IP_VS_DBG_RL("%s(): frag needed\n", __func__);
		goto tx_error_put;
	}

	/*
	 * Okay, now see if we can stuff it in the buffer as-is.
	 */
	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr);

	if (skb_headroom(skb) < max_headroom
	    || skb_cloned(skb) || skb_shared(skb)) {
		struct sk_buff *new_skb =
			skb_realloc_headroom(skb, max_headroom);
		if (!new_skb) {
			dst_release(&rt->dst);
			kfree_skb(skb);
			IP_VS_ERR_RL("%s(): no memory\n", __func__);
			return NF_STOLEN;
		}
		kfree_skb(skb);
		skb = new_skb;
		old_iph = ipv6_hdr(skb);
	}

	skb->transport_header = skb->network_header;

	skb_push(skb, sizeof(struct ipv6hdr));
	skb_reset_network_header(skb);
	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

	/* drop old route */
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);

	/*
	 *	Push down and install the IPIP header.
	 */
	iph			=	ipv6_hdr(skb);
	iph->version		=	6;
	iph->nexthdr		=	IPPROTO_IPV6;
	iph->payload_len	=	old_iph->payload_len;
	be16_add_cpu(&iph->payload_len, sizeof(*old_iph));
	iph->priority		=	old_iph->priority;
	memset(&iph->flow_lbl, 0, sizeof(iph->flow_lbl));
	iph->daddr = cp->daddr.in6;
	iph->saddr = saddr;
	iph->hop_limit		=	old_iph->hop_limit;

	/* Another hack: avoid icmp_send in ip_fragment */
	skb->local_df = 1;

	ret = IP_VS_XMIT_TUNNEL(skb, cp);
	if (ret == NF_ACCEPT)
		ip6_local_out(skb);
	else if (ret == NF_DROP)
		kfree_skb(skb);

//.........这里部分代码省略.........

//.........这里部分代码省略.........
	/*
	 *	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 up to and including the packet end
		   then align the next start on an eight byte boundary */
		if (len < left)	{
			len &= ~7;
		}

		/* Allocate buffer */
		frag = alloc_skb(len + hlen + sizeof(struct frag_hdr) +
				 hroom + troom, GFP_ATOMIC);
		if (!frag) {
			IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
				      IPSTATS_MIB_FRAGFAILS);
			err = -ENOMEM;
			goto fail;
		}

		/*
		 *	Set up data on packet
		 */

		ip6_copy_metadata(frag, skb);
		skb_reserve(frag, hroom);
		skb_put(frag, len + hlen + sizeof(struct frag_hdr));
		skb_reset_network_header(frag);
		fh = (struct frag_hdr *)(skb_network_header(frag) + hlen);
		frag->transport_header = (frag->network_header + hlen +
					  sizeof(struct frag_hdr));

		/*
		 *	Charge the memory for the fragment to any owner
		 *	it might possess
		 */
		if (skb->sk)
			skb_set_owner_w(frag, skb->sk);

		/*
		 *	Copy the packet header into the new buffer.
		 */
		skb_copy_from_linear_data(skb, skb_network_header(frag), hlen);

		/*
		 *	Build fragment header.
		 */
		fh->nexthdr = nexthdr;
		fh->reserved = 0;
		fh->identification = frag_id;

		/*
		 *	Copy a block of the IP datagram.
		 */
		BUG_ON(skb_copy_bits(skb, ptr, skb_transport_header(frag),
				     len));
		left -= len;

		fh->frag_off = htons(offset);
		if (left > 0)
			fh->frag_off |= htons(IP6_MF);
		ipv6_hdr(frag)->payload_len = htons(frag->len -
						    sizeof(struct ipv6hdr));

		ptr += len;
		offset += len;

		/*
		 *	Put this fragment into the sending queue.
		 */
		err = output(net, sk, frag);
		if (err)
			goto fail;

		IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
			      IPSTATS_MIB_FRAGCREATES);
	}
	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
		      IPSTATS_MIB_FRAGOKS);
	consume_skb(skb);
	return err;

fail_toobig:
	if (skb->sk && dst_allfrag(skb_dst(skb)))
		sk_nocaps_add(skb->sk, NETIF_F_GSO_MASK);

	skb->dev = skb_dst(skb)->dev;
	icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
	err = -EMSGSIZE;

fail:
	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
		      IPSTATS_MIB_FRAGFAILS);
	kfree_skb(skb);
	return err;
}

//.........这里部分代码省略.........
				goto err_unreach;
			}
			rt = (struct rt6_info *) dst;
			cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
			__ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie);
			spin_unlock_bh(&dest->dst_lock);
			IP_VS_DBG(10, "new dst %pI6, src %pI6, refcnt=%d\n",
				  &dest->addr.in6, &dest_dst->dst_saddr.in6,
				  atomic_read(&rt->dst.__refcnt));
		}
		if (ret_saddr)
			*ret_saddr = dest_dst->dst_saddr.in6;
	} else {
		noref = 0;
		dst = __ip_vs_route_output_v6(net, daddr, ret_saddr, do_xfrm);
		if (!dst)
			goto err_unreach;
		rt = (struct rt6_info *) dst;
	}

	local = __ip_vs_is_local_route6(rt);
	if (!((local ? IP_VS_RT_MODE_LOCAL : IP_VS_RT_MODE_NON_LOCAL) &
	      rt_mode)) {
		IP_VS_DBG_RL("Stopping traffic to %s address, dest: %pI6c\n",
			     local ? "local":"non-local", daddr);
		goto err_put;
	}
	if (likely(!local)) {
		if (unlikely((!skb->dev || skb->dev->flags & IFF_LOOPBACK) &&
			     ipv6_addr_type(&ipv6_hdr(skb)->saddr) &
					    IPV6_ADDR_LOOPBACK)) {
			IP_VS_DBG_RL("Stopping traffic from loopback address "
				     "%pI6c to non-local address, "
				     "dest: %pI6c\n",
				     &ipv6_hdr(skb)->saddr, daddr);
			goto err_put;
		}
	} else {
		ort = (struct rt6_info *) skb_dst(skb);
		if (!(rt_mode & IP_VS_RT_MODE_RDR) &&
		    !__ip_vs_is_local_route6(ort)) {
			IP_VS_DBG_RL("Redirect from non-local address %pI6c "
				     "to local requires NAT method, "
				     "dest: %pI6c\n",
				     &ipv6_hdr(skb)->daddr, daddr);
			goto err_put;
		}
		/* skb to local stack, preserve old route */
		if (!noref)
			dst_release(&rt->dst);
		return local;
	}

	/* MTU checking */
	if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL)))
		mtu = dst_mtu(&rt->dst);
	else {
		struct sock *sk = skb->sk;

		mtu = dst_mtu(&rt->dst) - sizeof(struct ipv6hdr);
		if (mtu < IPV6_MIN_MTU) {
			IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
				     IPV6_MIN_MTU);
			goto err_put;
		}
		ort = (struct rt6_info *) skb_dst(skb);
		if (!skb->dev && sk && sk->sk_state != TCP_TIME_WAIT)
			ort->dst.ops->update_pmtu(&ort->dst, sk, NULL, mtu);
	}

	if (unlikely(__mtu_check_toobig_v6(skb, mtu))) {
		if (!skb->dev)
			skb->dev = net->loopback_dev;
		/* only send ICMP too big on first fragment */
		if (!ipvsh->fragoffs)
			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		IP_VS_DBG(1, "frag needed for %pI6c\n", &ipv6_hdr(skb)->saddr);
		goto err_put;
	}

	skb_dst_drop(skb);
	if (noref) {
		if (!local)
			skb_dst_set_noref_force(skb, &rt->dst);
		else
			skb_dst_set(skb, dst_clone(&rt->dst));
	} else
		skb_dst_set(skb, &rt->dst);

	return local;

err_put:
	if (!noref)
		dst_release(&rt->dst);
	return -1;

err_unreach:
	dst_link_failure(skb);
	return -1;
}