C++ IP6CB函数代码示例

static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
			  struct net_device *dev)
{
	struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
	struct sk_buff *fp, *head = fq->q.fragments;
	int    payload_len;
	unsigned int nhoff;

	fq_kill(fq);

	
	if (prev) {
		head = prev->next;
		fp = skb_clone(head, GFP_ATOMIC);

		if (!fp)
			goto out_oom;

		fp->next = head->next;
		if (!fp->next)
			fq->q.fragments_tail = fp;
		prev->next = fp;

		skb_morph(head, fq->q.fragments);
		head->next = fq->q.fragments->next;

		kfree_skb(fq->q.fragments);
		fq->q.fragments = head;
	}

	WARN_ON(head == NULL);
	WARN_ON(FRAG6_CB(head)->offset != 0);

	
	payload_len = ((head->data - skb_network_header(head)) -
		       sizeof(struct ipv6hdr) + fq->q.len -
		       sizeof(struct frag_hdr));
	if (payload_len > IPV6_MAXPLEN)
		goto out_oversize;

	
	if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
		goto out_oom;

	if (skb_has_frag_list(head)) {
		struct sk_buff *clone;
		int i, plen = 0;

		if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
			goto out_oom;
		clone->next = head->next;
		head->next = clone;
		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
		skb_frag_list_init(head);
		for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
			plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
		clone->len = clone->data_len = head->data_len - plen;
		head->data_len -= clone->len;
		head->len -= clone->len;
		clone->csum = 0;
		clone->ip_summed = head->ip_summed;
		atomic_add(clone->truesize, &fq->q.net->mem);
	}

	nhoff = fq->nhoffset;
	skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
	memmove(head->head + sizeof(struct frag_hdr), head->head,
		(head->data - head->head) - sizeof(struct frag_hdr));
	head->mac_header += sizeof(struct frag_hdr);
	head->network_header += sizeof(struct frag_hdr);

	skb_shinfo(head)->frag_list = head->next;
	skb_reset_transport_header(head);
	skb_push(head, head->data - skb_network_header(head));

	for (fp=head->next; fp; fp = fp->next) {
		head->data_len += fp->len;
		head->len += fp->len;
		if (head->ip_summed != fp->ip_summed)
			head->ip_summed = CHECKSUM_NONE;
		else if (head->ip_summed == CHECKSUM_COMPLETE)
			head->csum = csum_add(head->csum, fp->csum);
		head->truesize += fp->truesize;
	}
	atomic_sub(head->truesize, &fq->q.net->mem);

	head->next = NULL;
	head->dev = dev;
	head->tstamp = fq->q.stamp;
	ipv6_hdr(head)->payload_len = htons(payload_len);
	IP6CB(head)->nhoff = nhoff;

	
	if (head->ip_summed == CHECKSUM_COMPLETE)
		head->csum = csum_partial(skb_network_header(head),
					  skb_network_header_len(head),
					  head->csum);

	rcu_read_lock();
	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	if (payload_len > IPV6_MAXPLEN)
		goto out_oversize;

	/* Head of list must not be cloned. */
	if (skb_unclone(head, GFP_ATOMIC))
		goto out_oom;

	/* If the first fragment is fragmented itself, we split
	 * it to two chunks: the first with data and paged part
	 * and the second, holding only fragments. */
	if (skb_has_frag_list(head)) {
		struct sk_buff *clone;
		int i, plen = 0;

		clone = alloc_skb(0, GFP_ATOMIC);
		if (!clone)
			goto out_oom;
		clone->next = head->next;
		head->next = clone;
		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
		skb_frag_list_init(head);
		for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
			plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
		clone->len = clone->data_len = head->data_len - plen;
		head->data_len -= clone->len;
		head->len -= clone->len;
		clone->csum = 0;
		clone->ip_summed = head->ip_summed;
		add_frag_mem_limit(fq->q.net, clone->truesize);
	}

	/* We have to remove fragment header from datagram and to relocate
	 * header in order to calculate ICV correctly. */
	nhoff = fq->nhoffset;
	skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
	memmove(head->head + sizeof(struct frag_hdr), head->head,
		(head->data - head->head) - sizeof(struct frag_hdr));
	if (skb_mac_header_was_set(head))
		head->mac_header += sizeof(struct frag_hdr);
	head->network_header += sizeof(struct frag_hdr);

	skb_reset_transport_header(head);
	skb_push(head, head->data - skb_network_header(head));

	sum_truesize = head->truesize;
	for (fp = head->next; fp;) {
		bool headstolen;
		int delta;
		struct sk_buff *next = fp->next;

		sum_truesize += fp->truesize;
		if (head->ip_summed != fp->ip_summed)
			head->ip_summed = CHECKSUM_NONE;
		else if (head->ip_summed == CHECKSUM_COMPLETE)
			head->csum = csum_add(head->csum, fp->csum);

		if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
			kfree_skb_partial(fp, headstolen);
		} else {
			if (!skb_shinfo(head)->frag_list)
				skb_shinfo(head)->frag_list = fp;
			head->data_len += fp->len;
			head->len += fp->len;
			head->truesize += fp->truesize;
		}
		fp = next;
	}
	sub_frag_mem_limit(fq->q.net, sum_truesize);

	head->next = NULL;
	head->dev = dev;
	head->tstamp = fq->q.stamp;
	ipv6_hdr(head)->payload_len = htons(payload_len);
	ipv6_change_dsfield(ipv6_hdr(head), 0xff, ecn);
	IP6CB(head)->nhoff = nhoff;
	IP6CB(head)->flags |= IP6SKB_FRAGMENTED;
	IP6CB(head)->frag_max_size = fq->q.max_size;

	/* Yes, and fold redundant checksum back. 8) */
	skb_postpush_rcsum(head, skb_network_header(head),
			   skb_network_header_len(head));

	rcu_read_lock();
	__IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
	rcu_read_unlock();
	fq->q.fragments = NULL;
	fq->q.fragments_tail = NULL;
	return 1;

out_oversize:
	net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len);
	goto out_fail;
out_oom:
	net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n");
out_fail:
	rcu_read_lock();
	__IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
	rcu_read_unlock();
	return -1;
}

int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
	struct ipv6hdr *hdr;
	u32 		pkt_len;
	struct inet6_dev *idev;

	if (skb->pkt_type == PACKET_OTHERHOST) {
		kfree_skb(skb);
		return 0;
	}

	rcu_read_lock();

	idev = __in6_dev_get(skb->dev);

	IP6_INC_STATS_BH(idev, IPSTATS_MIB_INRECEIVES);

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL || !idev || unlikely(idev->cnf.disable_ipv6)) {
		IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
		rcu_read_unlock();
//		goto out;
		kfree_skb(skb);
		return 0;
	}

	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));

	/*
	 * Store incoming device index. When the packet will
	 * be queued, we cannot refer to skb->dev anymore.
	 *
	 * BTW, when we send a packet for our own local address on a
	 * non-loopback interface (e.g. ethX), it is being delivered
	 * via the loopback interface (lo) here; skb->dev = &loopback_dev.
	 * It, however, should be considered as if it is being
	 * arrived via the sending interface (ethX), because of the
	 * nature of scoping architecture. --yoshfuji
	 */
	IP6CB(skb)->iif = skb->dst ? ip6_dst_idev(skb->dst)->dev->ifindex : dev->ifindex;

	if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
		goto err;

	hdr = skb->nh.ipv6h;

	if (hdr->version != 6)
		goto err;

	/*
	 * RFC4291 2.5.3
	 * A packet received on an interface with a destination address
	 * of loopback must be dropped.
	 */
	if (!(dev->flags & IFF_LOOPBACK) && ipv6_addr_loopback(&hdr->daddr))
                goto err;

	skb->h.raw = (u8 *)(hdr + 1);
	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);

	pkt_len = ntohs(hdr->payload_len);

	/* pkt_len may be zero if Jumbo payload option is present */
	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
		if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
			IP6_INC_STATS_BH(idev, IPSTATS_MIB_INTRUNCATEDPKTS);
			goto drop;
		}
		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
			IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
			goto drop;
		}
		hdr = skb->nh.ipv6h;
	}

	if (hdr->nexthdr == NEXTHDR_HOP) {
		if (ipv6_parse_hopopts(&skb) < 0) {
			IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
			rcu_read_unlock();
			return 0;
		}
	}

	rcu_read_unlock();

	return NF_HOOK(PF_INET6,NF_IP6_PRE_ROUTING, skb, dev, NULL, ip6_rcv_finish);
err:
	IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
drop:
	rcu_read_unlock();
	kfree_skb(skb);
//out:
	return 0;
}

int ip6_mc_input(struct sk_buff *skb)
{
	const struct ipv6hdr *hdr;
	int deliver;

	IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
			 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
			 skb->len);

	hdr = ipv6_hdr(skb);
	deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);

#ifdef CONFIG_IPV6_MROUTE
	/*
	 *      IPv6 multicast router mode is now supported ;)
	 */
	if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
	    !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
	    likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
		/*
		 * Okay, we try to forward - split and duplicate
		 * packets.
		 */
		struct sk_buff *skb2;
		struct inet6_skb_parm *opt = IP6CB(skb);

		/* Check for MLD */
		if (unlikely(opt->ra)) {
			/* Check if this is a mld message */
			u8 *ptr = skb_network_header(skb) + opt->ra;
			struct icmp6hdr *icmp6;
			u8 nexthdr = hdr->nexthdr;
			int offset;

			/* Check if the value of Router Alert
			 * is for MLD (0x0000).
			 */
			if ((ptr[2] | ptr[3]) == 0) {
				deliver = 0;

				if (!ipv6_ext_hdr(nexthdr)) {
					/* BUG */
					goto out;
				}
				offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
							  &nexthdr);
				if (offset < 0)
					goto out;

				if (nexthdr != IPPROTO_ICMPV6)
					goto out;

				if (!pskb_may_pull(skb, (skb_network_header(skb) +
						   offset + 1 - skb->data)))
					goto out;

				icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);

				switch (icmp6->icmp6_type) {
				case ICMPV6_MGM_QUERY:
				case ICMPV6_MGM_REPORT:
				case ICMPV6_MGM_REDUCTION:
				case ICMPV6_MLD2_REPORT:
					deliver = 1;
					break;
				}
				goto out;
			}
			/* unknown RA - process it normally */
		}

		if (deliver)
			skb2 = skb_clone(skb, GFP_ATOMIC);
		else {
			skb2 = skb;
			skb = NULL;
		}

		if (skb2) {
			ip6_mr_input(skb2);
		}
	}
out:
#endif
	if (likely(deliver))
		ip6_input(skb);
	else {
		/* discard */
		kfree_skb(skb);
	}

	return 0;
}

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

	err = ip6_find_1stfragopt(skb, &prevhdr);
	if (err < 0)
		goto fail;
	hlen = err;
	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 (unlikely(!skb->ignore_df && skb->len > mtu))
		goto fail_toobig;

	if (IP6CB(skb)->frag_max_size) {
		if (IP6CB(skb)->frag_max_size > mtu)
			goto fail_toobig;

		/* don't send fragments larger than what we received */
		mtu = IP6CB(skb)->frag_max_size;
		if (mtu < IPV6_MIN_MTU)
			mtu = IPV6_MIN_MTU;
	}

	if (np && np->frag_size < mtu) {
		if (np->frag_size)
			mtu = np->frag_size;
	}
	if (mtu < hlen + sizeof(struct frag_hdr) + 8)
		goto fail_toobig;
	mtu -= hlen + sizeof(struct frag_hdr);

	frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
				    &ipv6_hdr(skb)->saddr);

	if (skb->ip_summed == CHECKSUM_PARTIAL &&
	    (err = skb_checksum_help(skb)))
		goto fail;

	hroom = LL_RESERVED_SPACE(rt->dst.dev);
	if (skb_has_frag_list(skb)) {
		unsigned int first_len = skb_pagelen(skb);
		struct sk_buff *frag2;

		if (first_len - hlen > mtu ||
		    ((first_len - hlen) & 7) ||
		    skb_cloned(skb) ||
		    skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
			goto slow_path;

		skb_walk_frags(skb, frag) {
			/* Correct geometry. */
			if (frag->len > mtu ||
			    ((frag->len & 7) && frag->next) ||
			    skb_headroom(frag) < (hlen + hroom + sizeof(struct frag_hdr)))
				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;
		/* 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);
			err = -ENOMEM;
			goto fail;
		}
		frag = skb_shinfo(skb)->frag_list;
		skb_frag_list_init(skb);

		__skb_pull(skb, hlen);
//.........这里部分代码省略.........

static inline void
_decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
{
	int onlyproto = 0;
	u16 offset = skb_network_header_len(skb);
	struct ipv6hdr *hdr = ipv6_hdr(skb);
	struct ipv6_opt_hdr *exthdr;
	const unsigned char *nh = skb_network_header(skb);
	u8 nexthdr = nh[IP6CB(skb)->nhoff];

	memset(fl, 0, sizeof(struct flowi));
	ipv6_addr_copy(&fl->fl6_dst, reverse ? &hdr->saddr : &hdr->daddr);
	ipv6_addr_copy(&fl->fl6_src, reverse ? &hdr->daddr : &hdr->saddr);

	while (nh + offset + 1 < skb->data ||
	       pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
		nh = skb_network_header(skb);
		exthdr = (struct ipv6_opt_hdr *)(nh + offset);

		switch (nexthdr) {
		case NEXTHDR_FRAGMENT:
			onlyproto = 1;
		case NEXTHDR_ROUTING:
		case NEXTHDR_HOP:
		case NEXTHDR_DEST:
			offset += ipv6_optlen(exthdr);
			nexthdr = exthdr->nexthdr;
			exthdr = (struct ipv6_opt_hdr *)(nh + offset);
			break;

		case IPPROTO_UDP:
		case IPPROTO_UDPLITE:
		case IPPROTO_TCP:
		case IPPROTO_SCTP:
		case IPPROTO_DCCP:
			if (!onlyproto && (nh + offset + 4 < skb->data ||
			     pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
				__be16 *ports = (__be16 *)exthdr;

				fl->fl_ip_sport = ports[!!reverse];
				fl->fl_ip_dport = ports[!reverse];
			}
			fl->proto = nexthdr;
			return;

		case IPPROTO_ICMPV6:
			if (!onlyproto && pskb_may_pull(skb, nh + offset + 2 - skb->data)) {
				u8 *icmp = (u8 *)exthdr;

				fl->fl_icmp_type = icmp[0];
				fl->fl_icmp_code = icmp[1];
			}
			fl->proto = nexthdr;
			return;

#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
		case IPPROTO_MH:
			if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) {
				struct ip6_mh *mh;
				mh = (struct ip6_mh *)exthdr;

				fl->fl_mh_type = mh->ip6mh_type;
			}
			fl->proto = nexthdr;
			return;
#endif

		/* XXX Why are there these headers? */
		case IPPROTO_AH:
		case IPPROTO_ESP:
		case IPPROTO_COMP:
		default:
			fl->fl_ipsec_spi = 0;
			fl->proto = nexthdr;
			return;
		}
	}
}

static int ip6_input_finish(struct sk_buff *skb)
{
	struct net *net = dev_net(skb_dst(skb)->dev);
	const struct inet6_protocol *ipprot;
	struct inet6_dev *idev;
	unsigned int nhoff;
	int nexthdr;
	bool raw;

	/*
	 *	Parse extension headers
	 */

	rcu_read_lock();
resubmit:
	idev = ip6_dst_idev(skb_dst(skb));
	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);
	if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
		int ret;

		if (ipprot->flags & INET6_PROTO_FINAL) {
			const 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, skb_network_header_len(skb)))
				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);
			}
			kfree_skb(skb);
		} else {
			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
			consume_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;
}

int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
	const struct ipv6hdr *hdr;
	u32 		pkt_len;
	struct inet6_dev *idev;
	struct net *net = dev_net(skb->dev);

	if (skb->pkt_type == PACKET_OTHERHOST) {
		kfree_skb(skb);
		return NET_RX_DROP;
	}

	rcu_read_lock();

	idev = __in6_dev_get(skb->dev);

	IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
	    !idev || unlikely(idev->cnf.disable_ipv6)) {
		IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
		goto drop;
	}

	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));

	/*
	 * Store incoming device index. When the packet will
	 * be queued, we cannot refer to skb->dev anymore.
	 *
	 * BTW, when we send a packet for our own local address on a
	 * non-loopback interface (e.g. ethX), it is being delivered
	 * via the loopback interface (lo) here; skb->dev = loopback_dev.
	 * It, however, should be considered as if it is being
	 * arrived via the sending interface (ethX), because of the
	 * nature of scoping architecture. --yoshfuji
	 */
	IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;

	if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
		goto err;

	hdr = ipv6_hdr(skb);

	if (hdr->version != 6)
		goto err;

	/*
	 * RFC4291 2.5.3
	 * A packet received on an interface with a destination address
	 * of loopback must be dropped.
	 */
	if (!(dev->flags & IFF_LOOPBACK) &&
	    ipv6_addr_loopback(&hdr->daddr))
		goto err;

	/* RFC4291 2.7
	 * Nodes must not originate a packet to a multicast address whose scope
	 * field contains the reserved value 0; if such a packet is received, it
	 * must be silently dropped.
	 */
	if (ipv6_addr_is_multicast(&hdr->daddr) &&
	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
		goto err;

	/*
	 * RFC4291 2.7
	 * Multicast addresses must not be used as source addresses in IPv6
	 * packets or appear in any Routing header.
	 */
	if (ipv6_addr_is_multicast(&hdr->saddr))
		goto err;

	skb->transport_header = skb->network_header + sizeof(*hdr);
	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);

	pkt_len = ntohs(hdr->payload_len);

	/* pkt_len may be zero if Jumbo payload option is present */
	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
		if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
			IP6_INC_STATS_BH(net,
					 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
			goto drop;
		}
		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
			goto drop;
		}
		hdr = ipv6_hdr(skb);
	}

	if (hdr->nexthdr == NEXTHDR_HOP) {
		if (ipv6_parse_hopopts(skb) < 0) {
			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
			rcu_read_unlock();
			return NET_RX_DROP;
		}
	}

//.........这里部分代码省略.........

static int ipv6_frag_rcv(struct sk_buff *skb)
{
	struct frag_hdr *fhdr;
	struct frag_queue *fq;
	const struct ipv6hdr *hdr = ipv6_hdr(skb);
	struct net *net = dev_net(skb_dst(skb)->dev);
	int evicted;

	if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED)
		goto fail_hdr;

	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);

	/* Jumbo payload inhibits frag. header */
	if (hdr->payload_len==0)
		goto fail_hdr;

	if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
				 sizeof(struct frag_hdr))))
		goto fail_hdr;

	hdr = ipv6_hdr(skb);
	fhdr = (struct frag_hdr *)skb_transport_header(skb);

	if (!(fhdr->frag_off & htons(0xFFF9))) {
		/* It is not a fragmented frame */
		skb->transport_header += sizeof(struct frag_hdr);
		IP6_INC_STATS_BH(net,
				 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);

		IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
		IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
		return 1;
	}

	evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags, false);
	if (evicted)
		IP6_ADD_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
				 IPSTATS_MIB_REASMFAILS, evicted);

	fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr,
		     ip6_frag_ecn(hdr));
	if (fq != NULL) {
		int ret;

		spin_lock(&fq->q.lock);

		ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);

		spin_unlock(&fq->q.lock);
		inet_frag_put(&fq->q, &ip6_frags);
		return ret;
	}

	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
	kfree_skb(skb);
	return -1;

fail_hdr:
	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
	return -1;
}

static inline void
_decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
{
	struct flowi6 *fl6 = &fl->u.ip6;
	int onlyproto = 0;
	const struct ipv6hdr *hdr = ipv6_hdr(skb);
	u16 offset = sizeof(*hdr);
	struct ipv6_opt_hdr *exthdr;
	const unsigned char *nh = skb_network_header(skb);
	u16 nhoff = IP6CB(skb)->nhoff;
	int oif = 0;
	u8 nexthdr;

	if (!nhoff)
		nhoff = offsetof(struct ipv6hdr, nexthdr);

	nexthdr = nh[nhoff];

	if (skb_dst(skb))
		oif = skb_dst(skb)->dev->ifindex;

	memset(fl6, 0, sizeof(struct flowi6));
	fl6->flowi6_mark = skb->mark;
	fl6->flowi6_oif = reverse ? skb->skb_iif : oif;

	fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
	fl6->saddr = reverse ? hdr->daddr : hdr->saddr;

	while (nh + offset + 1 < skb->data ||
	       pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
		nh = skb_network_header(skb);
		exthdr = (struct ipv6_opt_hdr *)(nh + offset);

		switch (nexthdr) {
		case NEXTHDR_FRAGMENT:
			onlyproto = 1;
		case NEXTHDR_ROUTING:
		case NEXTHDR_HOP:
		case NEXTHDR_DEST:
			offset += ipv6_optlen(exthdr);
			nexthdr = exthdr->nexthdr;
			exthdr = (struct ipv6_opt_hdr *)(nh + offset);
			break;

		case IPPROTO_UDP:
		case IPPROTO_UDPLITE:
		case IPPROTO_TCP:
		case IPPROTO_SCTP:
		case IPPROTO_DCCP:
			if (!onlyproto && (nh + offset + 4 < skb->data ||
			     pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
				__be16 *ports;

				nh = skb_network_header(skb);
				ports = (__be16 *)(nh + offset);
				fl6->fl6_sport = ports[!!reverse];
				fl6->fl6_dport = ports[!reverse];
			}
			fl6->flowi6_proto = nexthdr;
			return;

		case IPPROTO_ICMPV6:
			if (!onlyproto && pskb_may_pull(skb, nh + offset + 2 - skb->data)) {
				u8 *icmp;

				nh = skb_network_header(skb);
				icmp = (u8 *)(nh + offset);
				fl6->fl6_icmp_type = icmp[0];
				fl6->fl6_icmp_code = icmp[1];
			}
			fl6->flowi6_proto = nexthdr;
			return;

#if IS_ENABLED(CONFIG_IPV6_MIP6)
		case IPPROTO_MH:
			offset += ipv6_optlen(exthdr);
			if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) {
				struct ip6_mh *mh;

				nh = skb_network_header(skb);
				mh = (struct ip6_mh *)(nh + offset);
				fl6->fl6_mh_type = mh->ip6mh_type;
			}
			fl6->flowi6_proto = nexthdr;
			return;
#endif

		/* XXX Why are there these headers? */
		case IPPROTO_AH:
		case IPPROTO_ESP:
		case IPPROTO_COMP:
		default:
			fl6->fl6_ipsec_spi = 0;
			fl6->flowi6_proto = nexthdr;
			return;
		}
	}
}

int xfrm6_rcv_spi(struct sk_buff *skb, __be32 spi)
{
	int err;
	__be32 seq;
	struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
	struct xfrm_state *x;
	int xfrm_nr = 0;
	int decaps = 0;
	int nexthdr;
	unsigned int nhoff;

	nhoff = IP6CB(skb)->nhoff;
	nexthdr = skb->nh.raw[nhoff];

	seq = 0;
	if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0)
		goto drop;

	do {
		struct ipv6hdr *iph = skb->nh.ipv6h;

		if (xfrm_nr == XFRM_MAX_DEPTH)
			goto drop;

		x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi,
				nexthdr != IPPROTO_IPIP ? nexthdr : IPPROTO_IPV6, AF_INET6);
		if (x == NULL)
			goto drop;
		spin_lock(&x->lock);
		if (unlikely(x->km.state != XFRM_STATE_VALID))
			goto drop_unlock;

		if (x->props.replay_window && xfrm_replay_check(x, seq))
			goto drop_unlock;

		if (xfrm_state_check_expire(x))
			goto drop_unlock;

		nexthdr = x->type->input(x, skb);
		if (nexthdr <= 0)
			goto drop_unlock;

		skb->nh.raw[nhoff] = nexthdr;

		if (x->props.replay_window)
			xfrm_replay_advance(x, seq);

		x->curlft.bytes += skb->len;
		x->curlft.packets++;

		spin_unlock(&x->lock);

		xfrm_vec[xfrm_nr++] = x;

		if (x->mode->input(x, skb))
			goto drop;

		if (x->props.mode == XFRM_MODE_TUNNEL) { /* XXX */
			decaps = 1;
			break;
		}

		if ((err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) < 0)
			goto drop;
	} while (!err);

	/* Allocate new secpath or COW existing one. */
	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
		struct sec_path *sp;
		sp = secpath_dup(skb->sp);
		if (!sp)
			goto drop;
		if (skb->sp)
			secpath_put(skb->sp);
		skb->sp = sp;
	}

	if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
		goto drop;

	memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
	       xfrm_nr * sizeof(xfrm_vec[0]));
	skb->sp->len += xfrm_nr;
	skb->ip_summed = CHECKSUM_NONE;

	nf_reset(skb);

	if (decaps) {
		dst_release(skb->dst);
		skb->dst = NULL;
		netif_rx(skb);
		return -1;
	} else {
#ifdef CONFIG_NETFILTER
		skb->nh.ipv6h->payload_len = htons(skb->len);
		__skb_push(skb, skb->data - skb->nh.raw);

		NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
			ip6_rcv_finish);
		return -1;
//.........这里部分代码省略.........

static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	struct nf_bridge_info *nf_bridge;
	unsigned int mtu_reserved;

	mtu_reserved = nf_bridge_mtu_reduction(skb);

	if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) {
		nf_bridge_info_free(skb);
		return br_dev_queue_push_xmit(net, sk, skb);
	}

	nf_bridge = nf_bridge_info_get(skb);

	/* This is wrong! We should preserve the original fragment
	 * boundaries by preserving frag_list rather than refragmenting.
	 */
	if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) &&
	    skb->protocol == htons(ETH_P_IP)) {
		struct brnf_frag_data *data;

		if (br_validate_ipv4(net, skb))
			goto drop;

		IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;

		nf_bridge_update_protocol(skb);

		data = this_cpu_ptr(&brnf_frag_data_storage);

		data->vlan_tci = skb->vlan_tci;
		data->vlan_proto = skb->vlan_proto;
		data->encap_size = nf_bridge_encap_header_len(skb);
		data->size = ETH_HLEN + data->encap_size;

		skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
						 data->size);

		return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
	}
	if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&
	    skb->protocol == htons(ETH_P_IPV6)) {
		const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
		struct brnf_frag_data *data;

		if (br_validate_ipv6(net, skb))
			goto drop;

		IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;

		nf_bridge_update_protocol(skb);

		data = this_cpu_ptr(&brnf_frag_data_storage);
		data->encap_size = nf_bridge_encap_header_len(skb);
		data->size = ETH_HLEN + data->encap_size;

		skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
						 data->size);

		if (v6ops)
			return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);

		kfree_skb(skb);
		return -EMSGSIZE;
	}
	nf_bridge_info_free(skb);
	return br_dev_queue_push_xmit(net, sk, skb);
 drop:
	kfree_skb(skb);
	return 0;
}

/* This is the 'purely bridged' case.  For IP, we pass the packet to
 * netfilter with indev and outdev set to the bridge device,
 * but we are still able to filter on the 'real' indev/outdev
 * because of the physdev module. For ARP, indev and outdev are the
 * bridge ports. */
static unsigned int br_nf_forward_ip(void *priv,
				     struct sk_buff *skb,
				     const struct nf_hook_state *state)
{
	struct nf_bridge_info *nf_bridge;
	struct net_device *parent;
	u_int8_t pf;

	if (!skb->nf_bridge)
		return NF_ACCEPT;

	/* Need exclusive nf_bridge_info since we might have multiple
	 * different physoutdevs. */
	if (!nf_bridge_unshare(skb))
		return NF_DROP;

	nf_bridge = nf_bridge_info_get(skb);
	if (!nf_bridge)
		return NF_DROP;

	parent = bridge_parent(state->out);
	if (!parent)
		return NF_DROP;

	if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
		pf = NFPROTO_IPV4;
	else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
		pf = NFPROTO_IPV6;
	else
		return NF_ACCEPT;

	nf_bridge_pull_encap_header(skb);

	if (skb->pkt_type == PACKET_OTHERHOST) {
		skb->pkt_type = PACKET_HOST;
		nf_bridge->pkt_otherhost = true;
	}

	if (pf == NFPROTO_IPV4) {
		if (br_validate_ipv4(state->net, skb))
			return NF_DROP;
		IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
	}

	if (pf == NFPROTO_IPV6) {
		if (br_validate_ipv6(state->net, skb))
			return NF_DROP;
		IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
	}

	nf_bridge->physoutdev = skb->dev;
	if (pf == NFPROTO_IPV4)
		skb->protocol = htons(ETH_P_IP);
	else
		skb->protocol = htons(ETH_P_IPV6);

	NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
		brnf_get_logical_dev(skb, state->in),
		parent,	br_nf_forward_finish);

	return NF_STOLEN;
}

static void vrf_ip6_input_dst(struct sk_buff *skb, struct net_device *vrf_dev,
			      int ifindex)
{
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	struct flowi6 fl6 = {
		.daddr          = iph->daddr,
		.saddr          = iph->saddr,
		.flowlabel      = ip6_flowinfo(iph),
		.flowi6_mark    = skb->mark,
		.flowi6_proto   = iph->nexthdr,
		.flowi6_iif     = ifindex,
	};
	struct net *net = dev_net(vrf_dev);
	struct rt6_info *rt6;

	rt6 = vrf_ip6_route_lookup(net, vrf_dev, &fl6, ifindex,
				   RT6_LOOKUP_F_HAS_SADDR | RT6_LOOKUP_F_IFACE);
	if (unlikely(!rt6))
		return;

	if (unlikely(&rt6->dst == &net->ipv6.ip6_null_entry->dst))
		return;

	skb_dst_set(skb, &rt6->dst);
}

static struct sk_buff *vrf_ip6_rcv(struct net_device *vrf_dev,
				   struct sk_buff *skb)
{
	int orig_iif = skb->skb_iif;
	bool need_strict;

	/* loopback traffic; do not push through packet taps again.
	 * Reset pkt_type for upper layers to process skb
	 */
	if (skb->pkt_type == PACKET_LOOPBACK) {
		skb->dev = vrf_dev;
		skb->skb_iif = vrf_dev->ifindex;
		IP6CB(skb)->flags |= IP6SKB_L3SLAVE;
		skb->pkt_type = PACKET_HOST;
		goto out;
	}

	/* if packet is NDISC or addressed to multicast or link-local
	 * then keep the ingress interface
	 */
	need_strict = rt6_need_strict(&ipv6_hdr(skb)->daddr);
	if (!ipv6_ndisc_frame(skb) && !need_strict) {
		vrf_rx_stats(vrf_dev, skb->len);
		skb->dev = vrf_dev;
		skb->skb_iif = vrf_dev->ifindex;

		skb_push(skb, skb->mac_len);
		dev_queue_xmit_nit(skb, vrf_dev);
		skb_pull(skb, skb->mac_len);

		IP6CB(skb)->flags |= IP6SKB_L3SLAVE;
	}

	if (need_strict)
		vrf_ip6_input_dst(skb, vrf_dev, orig_iif);

	skb = vrf_rcv_nfhook(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, vrf_dev);
out:
	return skb;
}

static struct sk_buff *ip6_rcv_core(struct sk_buff *skb, struct net_device *dev,
				    struct net *net)
{
	const struct ipv6hdr *hdr;
	u32 pkt_len;
	struct inet6_dev *idev;

	if (skb->pkt_type == PACKET_OTHERHOST) {
		kfree_skb(skb);
		return NULL;
	}

	rcu_read_lock();

	idev = __in6_dev_get(skb->dev);

	__IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len);

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
	    !idev || unlikely(idev->cnf.disable_ipv6)) {
		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
		goto drop;
	}

	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));

	/*
	 * Store incoming device index. When the packet will
	 * be queued, we cannot refer to skb->dev anymore.
	 *
	 * BTW, when we send a packet for our own local address on a
	 * non-loopback interface (e.g. ethX), it is being delivered
	 * via the loopback interface (lo) here; skb->dev = loopback_dev.
	 * It, however, should be considered as if it is being
	 * arrived via the sending interface (ethX), because of the
	 * nature of scoping architecture. --yoshfuji
	 */
	IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;

	if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
		goto err;

	hdr = ipv6_hdr(skb);

	if (hdr->version != 6)
		goto err;

	__IP6_ADD_STATS(net, idev,
			IPSTATS_MIB_NOECTPKTS +
				(ipv6_get_dsfield(hdr) & INET_ECN_MASK),
			max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
	/*
	 * RFC4291 2.5.3
	 * The loopback address must not be used as the source address in IPv6
	 * packets that are sent outside of a single node. [..]
	 * A packet received on an interface with a destination address
	 * of loopback must be dropped.
	 */
	if ((ipv6_addr_loopback(&hdr->saddr) ||
	     ipv6_addr_loopback(&hdr->daddr)) &&
	    !(dev->flags & IFF_LOOPBACK) &&
	    !netif_is_l3_master(dev))
		goto err;

	/* RFC4291 Errata ID: 3480
	 * Interface-Local scope spans only a single interface on a
	 * node and is useful only for loopback transmission of
	 * multicast.  Packets with interface-local scope received
	 * from another node must be discarded.
	 */
	if (!(skb->pkt_type == PACKET_LOOPBACK ||
	      dev->flags & IFF_LOOPBACK) &&
	    ipv6_addr_is_multicast(&hdr->daddr) &&
	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
		goto err;

	/* If enabled, drop unicast packets that were encapsulated in link-layer
	 * multicast or broadcast to protected against the so-called "hole-196"
	 * attack in 802.11 wireless.
	 */
	if (!ipv6_addr_is_multicast(&hdr->daddr) &&
	    (skb->pkt_type == PACKET_BROADCAST ||
	     skb->pkt_type == PACKET_MULTICAST) &&
	    idev->cnf.drop_unicast_in_l2_multicast)
		goto err;

	/* RFC4291 2.7
	 * Nodes must not originate a packet to a multicast address whose scope
	 * field contains the reserved value 0; if such a packet is received, it
	 * must be silently dropped.
	 */
	if (ipv6_addr_is_multicast(&hdr->daddr) &&
	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
		goto err;

	/*
	 * RFC4291 2.7
	 * Multicast addresses must not be used as source addresses in IPv6
	 * packets or appear in any Routing header.
	 */
//.........这里部分代码省略.........