C++ skb_dst_drop函数代码示例

int iptunnel_xmit(struct net *net, struct rtable *rt,
		  struct sk_buff *skb,
		  __be32 src, __be32 dst, __u8 proto,
		  __u8 tos, __u8 ttl, __be16 df)
{
	int pkt_len = skb->len;
	struct iphdr *iph;
	int err;

	nf_reset(skb);
	secpath_reset(skb);
	skb_clear_rxhash(skb);
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt_dst(rt));
#if 0
	/* Do not clear ovs_skb_cb.  It will be done in gso code. */
	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
#endif

	/* Push down and install the IP header. */
	__skb_push(skb, sizeof(struct iphdr));
	skb_reset_network_header(skb);

	iph = ip_hdr(skb);

	iph->version	=	4;
	iph->ihl	=	sizeof(struct iphdr) >> 2;
	iph->frag_off	=	df;
	iph->protocol	=	proto;
	iph->tos	=	tos;
	iph->daddr	=	dst;
	iph->saddr	=	src;
	iph->ttl	=	ttl;
	tunnel_ip_select_ident(skb,
			       (const struct iphdr *)skb_inner_network_header(skb),
			       &rt_dst(rt));

	err = ip_local_out(skb);
	if (unlikely(net_xmit_eval(err)))
		pkt_len = 0;
	return pkt_len;
}

static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
{
	to->pkt_type = from->pkt_type;
	to->priority = from->priority;
	to->protocol = from->protocol;
	skb_dst_drop(to);
	skb_dst_set(to, dst_clone(skb_dst(from)));
	to->dev = from->dev;
	to->mark = from->mark;

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

static int internal_dev_recv(struct vport *vport, struct sk_buff *skb)
{
	struct net_device *netdev = netdev_vport_priv(vport)->dev;
	int len;

	len = skb->len;

	skb_dst_drop(skb);
	nf_reset(skb);
	secpath_reset(skb);

	skb->dev = netdev;
	skb->pkt_type = PACKET_HOST;
	skb->protocol = eth_type_trans(skb, netdev);
	skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);

	netif_rx(skb);

	return len;
}

static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
{
	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
	struct net_device *dev = spriv->dev;
	struct l2tp_eth *priv = netdev_priv(dev);

	if (session->debug & L2TP_MSG_DATA) {
		unsigned int length;

		length = min(32u, skb->len);
		if (!pskb_may_pull(skb, length))
			goto error;

		pr_debug("%s: eth recv\n", session->name);
		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
	}

	if (!pskb_may_pull(skb, ETH_HLEN))
		goto error;

	secpath_reset(skb);

	/* checksums verified by L2TP */
	skb->ip_summed = CHECKSUM_NONE;

	skb_dst_drop(skb);
	nf_reset(skb);

	if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
		atomic_long_inc(&priv->rx_packets);
		atomic_long_add(data_len, &priv->rx_bytes);
	} else {
		atomic_long_inc(&priv->rx_errors);
	}
	return;

error:
	atomic_long_inc(&priv->rx_errors);
	kfree_skb(skb);
}

static int vrf_send_v4_prep(struct sk_buff *skb, struct flowi4 *fl4,
			    struct net_device *vrf_dev)
{
	struct rtable *rt;
	int err = 1;

	rt = ip_route_output_flow(dev_net(vrf_dev), fl4, NULL);
	if (IS_ERR(rt))
		goto out;

	/* TO-DO: what about broadcast ? */
	if (rt->rt_type != RTN_UNICAST && rt->rt_type != RTN_LOCAL) {
		ip_rt_put(rt);
		goto out;
	}

	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);
	err = 0;
out:
	return err;
}

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

	/* Copy the flags to each fragment. */
	IPCB(to)->flags = IPCB(from)->flags;

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

int ip6_route_me_harder(struct sk_buff *skb)
{
	struct net *net = dev_net(skb_dst(skb)->dev);
	struct ipv6hdr *iph = ipv6_hdr(skb);
	struct dst_entry *dst;
	struct flowi fl = {
		.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
		.mark = skb->mark,
		.nl_u =
		{ .ip6_u =
		  { .daddr = iph->daddr,
		    .saddr = iph->saddr, } },
	};

	dst = ip6_route_output(net, skb->sk, &fl);
	if (dst->error) {
		IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
		LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
		dst_release(dst);
		return -EINVAL;
	}

	/* Drop old route. */
	skb_dst_drop(skb);

	skb_dst_set(skb, dst);

#ifdef CONFIG_XFRM
	if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(skb, &fl, AF_INET6) == 0) {
		skb_dst_set(skb, NULL);
		if (xfrm_lookup(net, &dst, &fl, skb->sk, 0))
			return -1;
		skb_dst_set(skb, dst);
	}
#endif

	return 0;
}

/* If an incoming SYN or SYNACK frame contains a payload and/or FIN,
 * queue this additional data / FIN.
 */
void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb)
{
	struct tcp_sock *tp = tcp_sk(sk);

	if (TCP_SKB_CB(skb)->end_seq == tp->rcv_nxt)
		return;

	skb = skb_clone(skb, GFP_ATOMIC);
	if (!skb)
		return;

	skb_dst_drop(skb);
	/* segs_in has been initialized to 1 in tcp_create_openreq_child().
	 * Hence, reset segs_in to 0 before calling tcp_segs_in()
	 * to avoid double counting.  Also, tcp_segs_in() expects
	 * skb->len to include the tcp_hdrlen.  Hence, it should
	 * be called before __skb_pull().
	 */
	tp->segs_in = 0;
	tcp_segs_in(tp, skb);
	__skb_pull(skb, tcp_hdrlen(skb));
	sk_forced_mem_schedule(sk, skb->truesize);
	skb_set_owner_r(skb, sk);

	TCP_SKB_CB(skb)->seq++;
	TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_SYN;

	tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
	__skb_queue_tail(&sk->sk_receive_queue, skb);
	tp->syn_data_acked = 1;

	/* u64_stats_update_begin(&tp->syncp) not needed here,
	 * as we certainly are not changing upper 32bit value (0)
	 */
	tp->bytes_received = skb->len;

	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
		tcp_fin(sk);
}

int iptunnel_xmit(struct net *net, struct rtable *rt,
		  struct sk_buff *skb,
		  __be32 src, __be32 dst, __u8 proto,
		  __u8 tos, __u8 ttl, __be16 df)
{
	int pkt_len = skb->len;
	struct iphdr *iph;
	int err;

	nf_reset(skb);
	secpath_reset(skb);
	skb->rxhash = 0;
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);
	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));

	/* Push down and install the IP header. */
	skb_push(skb, sizeof(struct iphdr));
	skb_reset_network_header(skb);

	iph = ip_hdr(skb);

	iph->version	=	4;
	iph->ihl	=	sizeof(struct iphdr) >> 2;
	iph->frag_off	=	df;
	iph->protocol	=	proto;
	iph->tos	=	tos;
	iph->daddr	=	dst;
	iph->saddr	=	src;
	iph->ttl	=	ttl;
	__ip_select_ident(iph, &rt->dst, (skb_shinfo(skb)->gso_segs ?: 1) - 1);

	err = ip_local_out(skb);
	if (unlikely(net_xmit_eval(err)))
		pkt_len = 0;
	return pkt_len;
}

static int internal_dev_recv(struct vport *vport, struct sk_buff *skb)
{
	struct net_device *netdev = netdev_vport_priv(vport)->dev;
	int len;

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37)
	if (vlan_tx_tag_present(skb)) {
		if (unlikely(!__vlan_put_tag(skb,
					     skb->vlan_proto,
					     vlan_tx_tag_get(skb))))
			return 0;

		if (skb->ip_summed == CHECKSUM_COMPLETE)
			skb->csum = csum_add(skb->csum,
					     csum_partial(skb->data + (2 * ETH_ALEN),
							  VLAN_HLEN, 0));

		vlan_set_tci(skb, 0);
	}
#endif

	len = skb->len;

	skb_dst_drop(skb);
	nf_reset(skb);
	secpath_reset(skb);

	skb->dev = netdev;
	skb->pkt_type = PACKET_HOST;
	skb->protocol = eth_type_trans(skb, netdev);
	skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);

	netif_rx(skb);

	return len;
}

static void sc_send_80211(struct sk_buff *skb, struct net_device *dev)
{
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	struct ieee80211_hdr *hdr;
	int hdrlen;

	printk(KERN_DEBUG "capwap inject: %s: hdr: %p\n",
	       dev->name, skb->data);

	/* detach skb from CAPWAP */
	skb_orphan(skb);
	secpath_reset(skb);

	/* drop any routing info */
	skb_dst_drop(skb);

	/* drop conntrack reference */
	nf_reset(skb);

	hdr = (struct ieee80211_hdr *)skb->data;
	hdrlen = ieee80211_hdrlen(hdr->frame_control);

	skb->dev = dev;

	skb_set_mac_header(skb, hdrlen);
	skb_set_network_header(skb, hdrlen);
	skb_set_transport_header(skb, hdrlen);

	skb->protocol = htons(ETH_P_CONTROL);
	info->flags |= IEEE80211_TX_CTL_INJECTED;

	/* Force the device to verify it. */
	skb->ip_summed = CHECKSUM_NONE;

	dev_queue_xmit(skb);
}

int iptunnel_pull_header(struct sk_buff *skb, int hdr_len, __be16 inner_proto)
{
	if (unlikely(!pskb_may_pull(skb, hdr_len)))
		return -ENOMEM;

	skb_pull_rcsum(skb, hdr_len);

	if (inner_proto == htons(ETH_P_TEB)) {
		struct ethhdr *eh;

		if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
			return -ENOMEM;

		eh = (struct ethhdr *)skb->data;

		if (likely(ntohs(eh->h_proto) >= ETH_P_802_3_MIN))
			skb->protocol = eh->h_proto;
		else
			skb->protocol = htons(ETH_P_802_2);

	} else {
		skb->protocol = inner_proto;
	}

	if (unlikely(compute_ip_summed(skb, false)))
		return -EPROTO;

	nf_reset(skb);
	secpath_reset(skb);
	skb_clear_rxhash(skb);
	skb_dst_drop(skb);
	vlan_set_tci(skb, 0);
	skb_set_queue_mapping(skb, 0);
	skb->pkt_type = PACKET_HOST;
	return 0;
}

void kni_net_process_rx_packet(struct sk_buff *skb,
                               struct net_device *dev,
                               struct rw_kni_mbuf_metadata *meta_data)
{
  struct kni_dev *kni = netdev_priv(dev);
  
  skb->dev = dev;
  
  if (kni->no_pci){
    skb_reset_mac_header(skb);
    skb->protocol = htons(RW_KNI_VF_GET_MDATA_PAYLOAD(meta_data));
  } else {
    skb->protocol = eth_type_trans(skb, dev);
  }
  skb->ip_summed = CHECKSUM_UNNECESSARY;
  /*Eth-type trans would have populated the packet-type. Store
    the old packet-type and populate the new packet-type depending
    on the mbuf flags*/
  rw_fpath_kni_set_skb_packet_type(meta_data, skb);

  if (RW_KNI_VF_VALID_MDATA_NH_POLICY(meta_data)){
    int route_lookup;
    BUG_ON(RW_KNI_VF_VALID_MDATA_ENCAP(meta_data) == 0);
    switch(RW_KNI_VF_GET_MDATA_ENCAP(meta_data)){
      default:
        break;
      case 1: //AKKI fix this later
        {
          uint32_t daddr;
          
          memcpy(&daddr, RW_KNI_VF_GET_MDATA_NH_POLICY(meta_data), 4);
          route_lookup = ip_route_input_noref(skb, ntohl(daddr),
                                              ntohl(daddr), 0, dev);
          if (route_lookup){
            kni->rx_drop_noroute++;
          }else{
            struct neighbour *neigh;
            struct dst_entry *dst = dst_clone(skb_dst(skb));
            struct net_device *neighdev;
            skb_dst_drop(skb);
            neighdev = dst->dev;
            
            
            if (likely(neighdev)){
              rcu_read_lock_bh();
              neigh = __neigh_lookup(&arp_tbl, &daddr, neighdev, 1);
              if (likely(!neigh)){
                __neigh_event_send(neigh, NULL);
              }
              rcu_read_unlock_bh();
              neigh_release(neigh);
            }
            dst_release(dst);
          }
        }
        break;
      case 2:
        {
          struct neighbour *neigh = NULL;
          struct dst_entry *dst = NULL;
          int i;
          uint32_t *v6addr;
          struct flowi6 fl6;
          struct rt6_info *rt;
          struct net_device *neighdev;
          
          v6addr = (uint32_t*)RW_KNI_VF_GET_MDATA_NH_POLICY(meta_data);
          for (i = 0; i < 4; i++){
            fl6.daddr.s6_addr32[i] = htonl(v6addr[i]);
          }
          rt = rt6_lookup(dev_net(dev), &fl6.daddr,
                          NULL, 0, 0);
          if (!rt){
            kni->rx_drop_noroute++;
          }else{
            dst = &rt->dst;
            neighdev = dst->dev;
            if (likely(neighdev)){
              rcu_read_lock_bh();
              neigh = __neigh_lookup(ipv6_stub->nd_tbl,
                                     &fl6.daddr.s6_addr32[0],
                                     neighdev, 1);
              if (likely(!neigh)){
                __neigh_event_send(neigh, NULL);
              }
              rcu_read_unlock_bh();
              neigh_release(neigh);
            }
            dst_release(dst);
          }
        }
        break;
    }
  }

  /* Call netif interface */
  netif_rx(skb);
  
  /* Update statistics */
  kni->stats.rx_packets++;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
			}
			offset += 4;
		}
		if (flags&GRE_KEY) {
			key = *(__be32*)(h + offset);
			offset += 4;
		}
		if (flags&GRE_SEQ) {
			seqno = ntohl(*(__be32*)(h + offset));
			offset += 4;
		}
	}

	gre_proto = *(__be16 *)(h + 2);

	read_lock(&ipgre_lock);
	if ((tunnel = ipgre_tunnel_lookup(skb->dev,
					  iph->saddr, iph->daddr, key,
					  gre_proto))) {
		struct net_device_stats *stats = &tunnel->dev->stats;

		secpath_reset(skb);

		skb->protocol = gre_proto;
		/* WCCP version 1 and 2 protocol decoding.
		 * - Change protocol to IP
		 * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
		 */
		if (flags == 0 && gre_proto == htons(ETH_P_WCCP)) {
			skb->protocol = htons(ETH_P_IP);
			if ((*(h + offset) & 0xF0) != 0x40)
				offset += 4;
		}

		skb->mac_header = skb->network_header;
		__pskb_pull(skb, offset);
		skb_postpull_rcsum(skb, skb_transport_header(skb), offset);
		skb->pkt_type = PACKET_HOST;
#ifdef CONFIG_NET_IPGRE_BROADCAST
		if (ipv4_is_multicast(iph->daddr)) {
			/* Looped back packet, drop it! */
			if (skb_rtable(skb)->fl.iif == 0)
				goto drop;
			stats->multicast++;
			skb->pkt_type = PACKET_BROADCAST;
		}
#endif

		if (((flags&GRE_CSUM) && csum) ||
		    (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) {
			stats->rx_crc_errors++;
			stats->rx_errors++;
			goto drop;
		}
		if (tunnel->parms.i_flags&GRE_SEQ) {
			if (!(flags&GRE_SEQ) ||
			    (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) {
				stats->rx_fifo_errors++;
				stats->rx_errors++;
				goto drop;
			}
			tunnel->i_seqno = seqno + 1;
		}

		len = skb->len;

		/* Warning: All skb pointers will be invalidated! */
		if (tunnel->dev->type == ARPHRD_ETHER) {
			if (!pskb_may_pull(skb, ETH_HLEN)) {
				stats->rx_length_errors++;
				stats->rx_errors++;
				goto drop;
			}

			iph = ip_hdr(skb);
			skb->protocol = eth_type_trans(skb, tunnel->dev);
			skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
		}

		stats->rx_packets++;
		stats->rx_bytes += len;
		skb->dev = tunnel->dev;
		skb_dst_drop(skb);
		nf_reset(skb);

		skb_reset_network_header(skb);
		ipgre_ecn_decapsulate(iph, skb);

		netif_rx(skb);
		read_unlock(&ipgre_lock);
		return(0);
	}
	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);

drop:
	read_unlock(&ipgre_lock);
drop_nolock:
	kfree_skb(skb);
	return(0);
}

//.........这里部分代码省略.........
	}
	tdev = rt->u.dst.dev;

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

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

	if (mtu < 68) {
		stats->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))
		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), 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 (time_before(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);
			return NETDEV_TX_OK;
		}
		if (skb->sk)
			skb_set_owner_w(new_skb, skb->sk);
		dev_kfree_skb(skb);
		skb = new_skb;
		iph6 = ipv6_hdr(skb);
	}

	skb->transport_header = skb->network_header;
	skb_push(skb, sizeof(struct iphdr));
	skb_reset_network_header(skb);
	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
	IPCB(skb)->flags = 0;
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->u.dst);

	/*
	 *	Push down and install the IPIP header.
	 */

	iph 			=	ip_hdr(skb);
	iph->version		=	4;
	iph->ihl		=	sizeof(struct iphdr)>>2;
	if (mtu > IPV6_MIN_MTU)
		iph->frag_off	=	tiph->frag_off;
	else
		iph->frag_off	=	0;

	iph->protocol		=	IPPROTO_IPV6;
	iph->tos		=	INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
	iph->daddr		=	rt->rt_dst;
	iph->saddr		=	rt->rt_src;

	if ((iph->ttl = tiph->ttl) == 0)
		iph->ttl	=	iph6->hop_limit;

	nf_reset(skb);

	IPTUNNEL_XMIT();
	return NETDEV_TX_OK;

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