C++ consume_skb函数代码示例

/* userspace injects packet into plum */
int bpf_dp_channel_push_on_plum(struct datapath *dp, u32 plum_id, u32 port_id,
				u32 fwd_plum_id, u32 arg1, u32 arg2, u32 arg3,
				u32 arg4, struct sk_buff *skb, u32 direction)
{
	struct plum_stack stack = {};
	struct plum_stack_frame first_frame = {};
	struct plum_stack_frame *frame;
	struct bpf_dp_context *ctx;
	u32 dest;

	frame = &first_frame;
	frame->kmem = 0;

	INIT_LIST_HEAD(&stack.list);
	ctx = &frame->ctx;
	ctx->stack = &stack;
	ctx->skb = skb;
	ctx->dp = dp;
	bpf_dp_ctx_init(ctx);

	rcu_read_lock();

	if (direction == OVS_BPF_OUT_DIR) {
		ctx->context.plum_id = plum_id;
		stack.curr_frame = frame;
		bpf_forward(&ctx->context, port_id);
		execute_plums(&stack);
		consume_skb(skb);
	} else if (direction == OVS_BPF_IN_DIR) {
		dest = MUX(plum_id, port_id);
		frame->dest = dest;
		stack.curr_frame = NULL;
		list_add(&frame->link, &stack.list);
		execute_plums(&stack);
	} else if (direction == OVS_BPF_FWD_TO_PLUM) {
		ctx->context.plum_id = plum_id;
		ctx->context.arg1 = arg1;
		ctx->context.arg2 = arg2;
		ctx->context.arg3 = arg3;
		ctx->context.arg4 = arg4;
		stack.curr_frame = frame;
		bpf_forward_to_plum(&ctx->context, fwd_plum_id);
		execute_plums(&stack);
		consume_skb(skb);
	}

	rcu_read_unlock();

	return 0;
}

static unsigned int
synproxy_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_synproxy_info *info = par->targinfo;
	struct net *net = xt_net(par);
	struct synproxy_net *snet = synproxy_pernet(net);
	struct synproxy_options opts = {};
	struct tcphdr *th, _th;

	if (nf_ip6_checksum(skb, xt_hooknum(par), par->thoff, IPPROTO_TCP))
		return NF_DROP;

	th = skb_header_pointer(skb, par->thoff, sizeof(_th), &_th);
	if (th == NULL)
		return NF_DROP;

	if (!synproxy_parse_options(skb, par->thoff, th, &opts))
		return NF_DROP;

	if (th->syn && !(th->ack || th->fin || th->rst)) {
		/* Initial SYN from client */
		this_cpu_inc(snet->stats->syn_received);

		if (th->ece && th->cwr)
			opts.options |= XT_SYNPROXY_OPT_ECN;

		opts.options &= info->options;
		if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP)
			synproxy_init_timestamp_cookie(info, &opts);
		else
			opts.options &= ~(XT_SYNPROXY_OPT_WSCALE |
					  XT_SYNPROXY_OPT_SACK_PERM |
					  XT_SYNPROXY_OPT_ECN);

		synproxy_send_client_synack(net, skb, th, &opts);
		consume_skb(skb);
		return NF_STOLEN;

	} else if (th->ack && !(th->fin || th->rst || th->syn)) {
		/* ACK from client */
		if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) {
			consume_skb(skb);
			return NF_STOLEN;
		} else {
			return NF_DROP;
		}
	}

	return XT_CONTINUE;
}

/**
 * Before the last deliver skb to ETH_P_ALL is called, this registered handler will
 * be called. During this time, we will revert the pkt_type from control buf in skb
 * 
 * @param[in]  skb - double pointer to the skb in case we need to clone..
 *
 * @returns action that needs to be taken on the skb. we can consume it.
 */
rx_handler_result_t rw_fpath_kni_handle_frame(struct sk_buff **pskb)
{
  struct sk_buff *skb = (struct sk_buff *)*pskb;
  struct kni_dev *kni;
  rx_handler_result_t ret = RX_HANDLER_PASS;
  
  skb = skb_share_check(skb, GFP_ATOMIC);
  if (unlikely(!skb))
    return RX_HANDLER_CONSUMED;
  
  if (!skb->dev){
    KNI_ERR("No device in the skb in rx_handler\n");
    return RX_HANDLER_PASS;
  }
  
  kni = netdev_priv(skb->dev);
  if (!kni){
    KNI_ERR("no kni private data in the device in rx_handler\n");
    return RX_HANDLER_PASS;
  }
  
  *pskb = skb;
  switch (skb->pkt_type){
    case PACKET_OUTGOING:
      skb->pkt_type = PACKET_OTHERHOST;
      kni->rx_treat_as_tx_filtered++;
      consume_skb(skb);
      ret = RX_HANDLER_CONSUMED;
      break;
    case PACKET_LOOPBACK:
      skb->pkt_type = skb->mark;
      if (skb->pkt_type == PACKET_OTHERHOST){
        /*Force the packet to be accepted by the IP stack*/
        skb->pkt_type = 0;
      }
      kni->rx_treat_as_tx_delivered++;
      skb->mark = 0;
      break;
    case PACKET_OTHERHOST:
      kni->rx_filtered++;
      consume_skb(skb);
      ret = RX_HANDLER_CONSUMED;
      break;
    default:
      kni->rx_delivered++;
      break;
  }
  return ret;
}

static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
		   struct packet_type *pt, struct net_device *orig_dev)
{
	const struct arphdr *arp;

	/* do not tweak dropwatch on an ARP we will ignore */
	if (dev->flags & IFF_NOARP ||
	    skb->pkt_type == PACKET_OTHERHOST ||
	    skb->pkt_type == PACKET_LOOPBACK)
		goto consumeskb;

	skb = skb_share_check(skb, GFP_ATOMIC);
	if (!skb)
		goto out_of_mem;

	/* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
	if (!pskb_may_pull(skb, arp_hdr_len(dev)))
		goto freeskb;

	arp = arp_hdr(skb);
	if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
		goto freeskb;

	memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));

	return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);

consumeskb:
	consume_skb(skb);
	return 0;
freeskb:
	kfree_skb(skb);
out_of_mem:
	return 0;
}

/* packet arriving on vport processed here
 * must be called with rcu_read_lock
 */
void bpf_dp_process_received_packet(struct vport *p, struct sk_buff *skb)
{
	struct datapath *dp = p->dp;
	struct plum *plum;
	u32 dest;
	struct plum_stack stack = {};
	struct plum_stack_frame first_frame = {};
	struct plum_stack_frame *frame;
	struct bpf_dp_context *ctx;

	plum = rcu_dereference(dp->plums[0]);
	dest = atomic_read(&plum->ports[p->port_no]);

	if (dest) {
		frame = &first_frame;

		INIT_LIST_HEAD(&stack.list);
		ctx = &frame->ctx;
		ctx->stack = &stack;
		ctx->context.port_id = p->port_no;
		ctx->skb = skb;
		ctx->dp = dp;
		bpf_dp_ctx_init(ctx);

		plum_update_stats(plum, p->port_no, skb, true);

		frame->dest = dest;
		stack.curr_frame = NULL;
		list_add(&frame->link, &stack.list);
		execute_plums(&stack);
	} else {
		consume_skb(skb);
	}
}

static struct sock *run_bpf(struct sock_reuseport *reuse, u16 socks,
			    struct bpf_prog *prog, struct sk_buff *skb,
			    int hdr_len)
{
	struct sk_buff *nskb = NULL;
	u32 index;

	if (skb_shared(skb)) {
		nskb = skb_clone(skb, GFP_ATOMIC);
		if (!nskb)
			return NULL;
		skb = nskb;
	}

	/* temporarily advance data past protocol header */
	if (!pskb_pull(skb, hdr_len)) {
		kfree_skb(nskb);
		return NULL;
	}
	index = bpf_prog_run_save_cb(prog, skb);
	__skb_push(skb, hdr_len);

	consume_skb(nskb);

	if (index >= socks)
		return NULL;

	return reuse->socks[index];
}

static struct sk_buff *skb_set_peeked(struct sk_buff *skb)
{
    struct sk_buff *nskb;

    if (skb->peeked)
        return skb;

    /* We have to unshare an skb before modifying it. */
    if (!skb_shared(skb))
        goto done;

    nskb = skb_clone(skb, GFP_ATOMIC);
    if (!nskb)
        return ERR_PTR(-ENOMEM);

    skb->prev->next = nskb;
    skb->next->prev = nskb;
    nskb->prev = skb->prev;
    nskb->next = skb->next;

    consume_skb(skb);
    skb = nskb;

done:
    skb->peeked = 1;

    return skb;
}

struct sk_buff *ax25_rt_build_path(struct sk_buff *skb, ax25_address *src,
	ax25_address *dest, ax25_digi *digi)
{
	struct sk_buff *skbn;
	unsigned char *bp;
	int len;

	len = digi->ndigi * AX25_ADDR_LEN;

	if (skb_headroom(skb) < len) {
		if ((skbn = skb_realloc_headroom(skb, len)) == NULL) {
			printk(KERN_CRIT "AX.25: ax25_dg_build_path - out of memory\n");
			return NULL;
		}

		if (skb->sk != NULL)
			skb_set_owner_w(skbn, skb->sk);

		consume_skb(skb);

		skb = skbn;
	}

	bp = skb_push(skb, len);

	ax25_addr_build(bp, src, dest, digi, AX25_COMMAND, AX25_MODULUS);

	return skb;
}

/* GSO packet is too big, segment it so that tbf can transmit
 * each segment in time
 */
static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch)
{
	struct tbf_sched_data *q = qdisc_priv(sch);
	struct sk_buff *segs, *nskb;
	netdev_features_t features = netif_skb_features(skb);
	int ret, nb;

	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);

	if (IS_ERR_OR_NULL(segs))
		return qdisc_reshape_fail(skb, sch);

	nb = 0;
	while (segs) {
		nskb = segs->next;
		segs->next = NULL;
		qdisc_skb_cb(segs)->pkt_len = segs->len;
		ret = qdisc_enqueue(segs, q->qdisc);
		if (ret != NET_XMIT_SUCCESS) {
			if (net_xmit_drop_count(ret))
				sch->qstats.drops++;
		} else {
			nb++;
		}
		segs = nskb;
	}
	sch->q.qlen += nb;
	if (nb > 1)
		qdisc_tree_decrease_qlen(sch, 1 - nb);
	consume_skb(skb);
	return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP;
}

/* called if GSO skb needs to be fragmented on forward */
static int ip_forward_finish_gso(struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	netdev_features_t features;
	struct sk_buff *segs;
	int ret = 0;

	features = netif_skb_dev_features(skb, dst->dev);
	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
	if (IS_ERR(segs)) {
		kfree_skb(skb);
		return -ENOMEM;
	}

	consume_skb(skb);

	do {
		struct sk_buff *nskb = segs->next;
		int err;

		segs->next = NULL;
		err = dst_output(segs);

		if (err && ret == 0)
			ret = err;
		segs = nskb;
	} while (segs);

	return ret;
}

/* GSO packet is too big, segment it so that tbf can transmit
 * each segment in time
 */
static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch,
		       struct sk_buff **to_free)
{
	struct tbf_sched_data *q = qdisc_priv(sch);
	struct sk_buff *segs, *nskb;
	netdev_features_t features = netif_skb_features(skb);
	unsigned int len = 0, prev_len = qdisc_pkt_len(skb);
	int ret, nb;

	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);

	if (IS_ERR_OR_NULL(segs))
		return qdisc_drop(skb, sch, to_free);

	nb = 0;
	while (segs) {
		nskb = segs->next;
		skb_mark_not_on_list(segs);
		qdisc_skb_cb(segs)->pkt_len = segs->len;
		len += segs->len;
		ret = qdisc_enqueue(segs, q->qdisc, to_free);
		if (ret != NET_XMIT_SUCCESS) {
			if (net_xmit_drop_count(ret))
				qdisc_qstats_drop(sch);
		} else {
			nb++;
		}
		segs = nskb;
	}
	sch->q.qlen += nb;
	if (nb > 1)
		qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
	consume_skb(skb);
	return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP;
}

void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
{
	struct sk_buff *skbn;
	unsigned char *ptr;
	int headroom;

	if (ax25->ax25_dev == NULL) {
		ax25_disconnect(ax25, ENETUNREACH);
		return;
	}

	headroom = ax25_addr_size(ax25->digipeat);

	if (skb_headroom(skb) < headroom) {
		if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
			printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
			kfree_skb(skb);
			return;
		}

		if (skb->sk != NULL)
			skb_set_owner_w(skbn, skb->sk);

		consume_skb(skb);
		skb = skbn;
	}

	ptr = skb_push(skb, headroom);

	ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);

	ax25_queue_xmit(skb, ax25->ax25_dev->dev);
}

/* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
 * value if 'skb' is freed.
 */
static int handle_fragments(struct net *net, struct sw_flow_key *key,
			    u16 zone, struct sk_buff *skb)
{
	struct ovs_gso_cb ovs_cb = *OVS_GSO_CB(skb);

	if (!skb->dev) {
		OVS_NLERR(true, "%s: skb has no dev; dropping", __func__);
		return -EINVAL;
	}

	if (key->eth.type == htons(ETH_P_IP)) {
		enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone;
		int err;

		memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
		err = ip_defrag(skb, user);
		if (err)
			return err;

		ovs_cb.dp_cb.mru = IPCB(skb)->frag_max_size;
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
	} else if (key->eth.type == htons(ETH_P_IPV6)) {
		enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;
		struct sk_buff *reasm;

		memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
		reasm = nf_ct_frag6_gather(skb, user);
		if (!reasm)
			return -EINPROGRESS;

		if (skb == reasm) {
			kfree_skb(skb);
			return -EINVAL;
		}

		/* Don't free 'skb' even though it is one of the original
		 * fragments, as we're going to morph it into the head.
		 */
		skb_get(skb);
		nf_ct_frag6_consume_orig(reasm);

		key->ip.proto = ipv6_hdr(reasm)->nexthdr;
		skb_morph(skb, reasm);
		skb->next = reasm->next;
		consume_skb(reasm);
		ovs_cb.dp_cb.mru = IP6CB(skb)->frag_max_size;
#endif /* IP frag support */
	} else {
		kfree_skb(skb);
		return -EPFNOSUPPORT;
	}

	key->ip.frag = OVS_FRAG_TYPE_NONE;
	skb_clear_hash(skb);
	skb->ignore_df = 1;
	*OVS_GSO_CB(skb) = ovs_cb;

	return 0;
}

static netdev_tx_t baseband_usb_netdev_start_xmit(
	struct sk_buff *skb, struct net_device *dev)
{
	int i = 0;
	struct baseband_usb *usb = netdev_priv(dev);/*wjp for pm*/
	struct urb *urb;
	unsigned char *buf;
	int err;

	pr_debug("baseband_usb_netdev_start_xmit\n");

	/* check input */
	if (!skb) {
		pr_err("no skb\n");
		return -EINVAL;
	}

	/* allocate urb */
	urb = usb_alloc_urb(0, GFP_ATOMIC);
	if (!urb) {
		pr_err("usb_alloc_urb() failed\n");
		return -ENOMEM;
	}
	buf = kzalloc(skb->len - 14, GFP_ATOMIC);
	if (!buf) {
		pr_err("usb buffer kzalloc() failed\n");
		usb_free_urb(urb);
		return -ENOMEM;
	}
	err = skb_copy_bits(skb, 14, buf, skb->len - 14);
	if (err < 0) {
		pr_err("skb_copy_bits() failed - %d\n", err);
		kfree(buf);
		usb_free_urb(urb);
		return err;
	}
	usb_fill_bulk_urb(urb, usb->usb.device, usb->usb.pipe.bulk.out,
		buf, skb->len - 14,
		usb_net_raw_ip_tx_urb_comp,
		usb);
	urb->transfer_flags = URB_ZERO_PACKET;

	/* submit tx urb */
	usb->usb.tx_urb = urb;
	err = usb_submit_urb(urb, GFP_ATOMIC);
	if (err < 0) {
		pr_err("usb_submit_urb() failed - err %d\n", err);
		usb->usb.tx_urb = (struct urb *) 0;
		kfree(urb->transfer_buffer);
		usb_free_urb(urb);
		kfree_skb(skb);
		return err;
	}

	/* free skb */
	consume_skb(skb);

	return NETDEV_TX_OK;
}

static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
{
	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
	struct net_device_stats *stats = &dev->stats;
	int loop;

	if (can_dropped_invalid_skb(dev, skb))
		return NETDEV_TX_OK;

	stats->tx_packets++;
	stats->tx_bytes += cfd->len;

	/* set flag whether this packet has to be looped back */
	loop = skb->pkt_type == PACKET_LOOPBACK;

	if (!echo) {
		/* no echo handling available inside this driver */

		if (loop) {
			/*
			 * only count the packets here, because the
			 * CAN core already did the echo for us
			 */
			stats->rx_packets++;
			stats->rx_bytes += cfd->len;
		}
		consume_skb(skb);
		return NETDEV_TX_OK;
	}

	/* perform standard echo handling for CAN network interfaces */

	if (loop) {

		skb = can_create_echo_skb(skb);
		if (!skb)
			return NETDEV_TX_OK;

		/* receive with packet counting */
		vcan_rx(skb, dev);
	} else {
		/* no looped packets => no counting */
		consume_skb(skb);
	}
	return NETDEV_TX_OK;
}