C++ rcu_dereference函数代码示例

/*
 * check with the fileserver to see if the directory or parent directory is
 * permitted to be accessed with this authorisation, and if so, what access it
 * is granted
 */
static int afs_check_permit(struct afs_vnode *vnode, struct key *key,
			    afs_access_t *_access)
{
	struct afs_permits *permits;
	struct afs_permit *permit;
	struct afs_vnode *auth_vnode;
	bool valid;
	int loop, ret;

	_enter("{%x:%u},%x",
	       vnode->fid.vid, vnode->fid.vnode, key_serial(key));

	auth_vnode = afs_get_auth_inode(vnode, key);
	if (IS_ERR(auth_vnode)) {
		*_access = 0;
		_leave(" = %ld", PTR_ERR(auth_vnode));
		return PTR_ERR(auth_vnode);
	}

	ASSERT(S_ISDIR(auth_vnode->vfs_inode.i_mode));

	/* check the permits to see if we've got one yet */
	if (key == auth_vnode->volume->cell->anonymous_key) {
		_debug("anon");
		*_access = auth_vnode->status.anon_access;
		valid = true;
	} else {
		valid = false;
		rcu_read_lock();
		permits = rcu_dereference(auth_vnode->permits);
		if (permits) {
			permit = permits->permits;
			for (loop = permits->count; loop > 0; loop--) {
				if (permit->key == key) {
					_debug("found in cache");
					*_access = permit->access_mask;
					valid = true;
					break;
				}
				permit++;
			}
		}
		rcu_read_unlock();
	}

	if (!valid) {
		/* check the status on the file we're actually interested in
		 * (the post-processing will cache the result on auth_vnode) */
		_debug("no valid permit");

		set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
		ret = afs_vnode_fetch_status(vnode, auth_vnode, key);
		if (ret < 0) {
			iput(&auth_vnode->vfs_inode);
			*_access = 0;
			_leave(" = %d", ret);
			return ret;
		}
		*_access = vnode->status.caller_access;
	}

	iput(&auth_vnode->vfs_inode);
	_leave(" = 0 [access %x]", *_access);
	return 0;
}

/* Expects to be always run from workqueue - which acts as
 * read-size critical section for our kind of RCU. */
static void handle_tx(struct vhost_net *net)
{
	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
	unsigned head, out, in, s;
	struct msghdr msg = {
		.msg_name = NULL,
		.msg_namelen = 0,
		.msg_control = NULL,
		.msg_controllen = 0,
		.msg_iov = vq->iov,
		.msg_flags = MSG_DONTWAIT,
	};
	size_t len, total_len = 0;
	int err, wmem;
	size_t hdr_size;
	struct socket *sock = rcu_dereference(vq->private_data);
	if (!sock)
		return;

	wmem = atomic_read(&sock->sk->sk_wmem_alloc);
	if (wmem >= sock->sk->sk_sndbuf) {
		mutex_lock(&vq->mutex);
		tx_poll_start(net, sock);
		mutex_unlock(&vq->mutex);
		return;
	}

	use_mm(net->dev.mm);
	mutex_lock(&vq->mutex);
	vhost_disable_notify(vq);

	if (wmem < sock->sk->sk_sndbuf * 2)
		tx_poll_stop(net);
	hdr_size = vq->hdr_size;

	for (;;) {
		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
					 ARRAY_SIZE(vq->iov),
					 &out, &in,
					 NULL, NULL);
		/* Nothing new?  Wait for eventfd to tell us they refilled. */
		if (head == vq->num) {
			wmem = atomic_read(&sock->sk->sk_wmem_alloc);
			if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
				tx_poll_start(net, sock);
				set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
				break;
			}
			if (unlikely(vhost_enable_notify(vq))) {
				vhost_disable_notify(vq);
				continue;
			}
			break;
		}
		if (in) {
			vq_err(vq, "Unexpected descriptor format for TX: "
			       "out %d, int %d\n", out, in);
			break;
		}
		/* Skip header. TODO: support TSO. */
		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
		msg.msg_iovlen = out;
		len = iov_length(vq->iov, out);
		/* Sanity check */
		if (!len) {
			vq_err(vq, "Unexpected header len for TX: "
			       "%zd expected %zd\n",
			       iov_length(vq->hdr, s), hdr_size);
			break;
		}
		/* TODO: Check specific error and bomb out unless ENOBUFS? */
		err = sock->ops->sendmsg(NULL, sock, &msg, len);
		if (unlikely(err < 0)) {
			vhost_discard_vq_desc(vq);
			tx_poll_start(net, sock);
			break;
		}
		if (err != len)
			pr_err("Truncated TX packet: "
			       " len %d != %zd\n", err, len);
		vhost_add_used_and_signal(&net->dev, vq, head, 0);
		total_len += len;
		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
			vhost_poll_queue(&vq->poll);
			break;
		}
	}

	mutex_unlock(&vq->mutex);
	unuse_mm(net->dev.mm);
}

/* Expects to be always run from workqueue - which acts as
 * read-size critical section for our kind of RCU. */
static void handle_rx(struct vhost_net *net)
{
	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
	unsigned head, out, in, log, s;
//.........这里部分代码省略.........

static inline int ip6_input_finish(struct sk_buff *skb)
{
	struct inet6_protocol *ipprot;
	struct sock *raw_sk;
	unsigned int nhoff;
	int nexthdr;
	u8 hash;
	struct inet6_dev *idev;

	/*
	 *	Parse extension headers
	 */

	rcu_read_lock();
resubmit:
	idev = ip6_dst_idev(skb->dst);
	if (!pskb_pull(skb, skb->h.raw - skb->data))
		goto discard;
	nhoff = IP6CB(skb)->nhoff;
	nexthdr = skb->nh.raw[nhoff];

	raw_sk = sk_head(&raw_v6_htable[nexthdr & (MAX_INET_PROTOS - 1)]);
	if (raw_sk && !ipv6_raw_deliver(skb, nexthdr))
		raw_sk = NULL;

	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->nh.raw,
					   skb->h.raw - skb->nh.raw);
			hdr = skb->nh.ipv6h;
			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 (!(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(idev, IPSTATS_MIB_INDELIVERS);
	} else {
		if (!raw_sk) {
			if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
				IP6_INC_STATS_BH(idev, IPSTATS_MIB_INUNKNOWNPROTOS);
				icmpv6_send(skb, ICMPV6_PARAMPROB,
					    ICMPV6_UNK_NEXTHDR, nhoff,
					    skb->dev);
			}
		} else
			IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
		kfree_skb(skb);
	}
	rcu_read_unlock();
	return 0;

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

static int __init nf_nat_ftp_init(void)
{
	BUG_ON(rcu_dereference(nf_nat_ftp_hook));
	rcu_assign_pointer(nf_nat_ftp_hook, nf_nat_ftp);
	return 0;
}

/*
 * Get the appropriate destination keyring for the request.
 *
 * The keyring selected is returned with an extra reference upon it which the
 * caller must release.
 */
static void construct_get_dest_keyring(struct key **_dest_keyring)
{
	struct request_key_auth *rka;
	const struct cred *cred = current_cred();
	struct key *dest_keyring = *_dest_keyring, *authkey;

	kenter("%p", dest_keyring);

	/* find the appropriate keyring */
	if (dest_keyring) {
		/* the caller supplied one */
		key_get(dest_keyring);
	} else {
		/* use a default keyring; falling through the cases until we
		 * find one that we actually have */
		switch (cred->jit_keyring) {
		case KEY_REQKEY_DEFL_DEFAULT:
		case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
			if (cred->request_key_auth) {
				authkey = cred->request_key_auth;
				down_read(&authkey->sem);
				rka = authkey->payload.data;
				if (!test_bit(KEY_FLAG_REVOKED,
					      &authkey->flags))
					dest_keyring =
						key_get(rka->dest_keyring);
				up_read(&authkey->sem);
				if (dest_keyring)
					break;
			}

		case KEY_REQKEY_DEFL_THREAD_KEYRING:
			dest_keyring = key_get(cred->thread_keyring);
			if (dest_keyring)
				break;

		case KEY_REQKEY_DEFL_PROCESS_KEYRING:
			dest_keyring = key_get(cred->tgcred->process_keyring);
			if (dest_keyring)
				break;

		case KEY_REQKEY_DEFL_SESSION_KEYRING:
			rcu_read_lock();
			dest_keyring = key_get(
				rcu_dereference(cred->tgcred->session_keyring));
			rcu_read_unlock();

			if (dest_keyring)
				break;

		case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
			dest_keyring =
				key_get(cred->user->session_keyring);
			break;

		case KEY_REQKEY_DEFL_USER_KEYRING:
			dest_keyring = key_get(cred->user->uid_keyring);
			break;

		case KEY_REQKEY_DEFL_GROUP_KEYRING:
		default:
			BUG();
		}
	}

	*_dest_keyring = dest_keyring;
	kleave(" [dk %d]", key_serial(dest_keyring));
	return;
}

static inline struct net_device *bridge_parent(const struct net_device *dev)
{
	struct net_bridge_port *port = rcu_dereference(dev->br_port);

	return port ? port->br->dev : NULL;
}

static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
			struct packet_type *pt, struct net_device *orig_dev)
{
	struct net *net = dev_net(dev);
	struct mpls_shim_hdr *hdr;
	struct mpls_route *rt;
	struct mpls_entry_decoded dec;
	struct net_device *out_dev;
	struct mpls_dev *mdev;
	unsigned int hh_len;
	unsigned int new_header_size;
	unsigned int mtu;
	int err;

	/* Careful this entire function runs inside of an rcu critical section */

	mdev = mpls_dev_get(dev);
	if (!mdev || !mdev->input_enabled)
		goto drop;

	if (skb->pkt_type != PACKET_HOST)
		goto drop;

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
		goto drop;

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

	/* Read and decode the label */
	hdr = mpls_hdr(skb);
	dec = mpls_entry_decode(hdr);

	/* Pop the label */
	skb_pull(skb, sizeof(*hdr));
	skb_reset_network_header(skb);

	skb_orphan(skb);

	rt = mpls_route_input_rcu(net, dec.label);
	if (!rt)
		goto drop;

	/* Find the output device */
	out_dev = rcu_dereference(rt->rt_dev);
	if (!mpls_output_possible(out_dev))
		goto drop;

	if (skb_warn_if_lro(skb))
		goto drop;

	skb_forward_csum(skb);

	/* Verify ttl is valid */
	if (dec.ttl <= 1)
		goto drop;
	dec.ttl -= 1;

	/* Verify the destination can hold the packet */
	new_header_size = mpls_rt_header_size(rt);
	mtu = mpls_dev_mtu(out_dev);
	if (mpls_pkt_too_big(skb, mtu - new_header_size))
		goto drop;

	hh_len = LL_RESERVED_SPACE(out_dev);
	if (!out_dev->header_ops)
		hh_len = 0;

	/* Ensure there is enough space for the headers in the skb */
	if (skb_cow(skb, hh_len + new_header_size))
		goto drop;

	skb->dev = out_dev;
	skb->protocol = htons(ETH_P_MPLS_UC);

	if (unlikely(!new_header_size && dec.bos)) {
		/* Penultimate hop popping */
		if (!mpls_egress(rt, skb, dec))
			goto drop;
	} else {
		bool bos;
		int i;
		skb_push(skb, new_header_size);
		skb_reset_network_header(skb);
		/* Push the new labels */
		hdr = mpls_hdr(skb);
		bos = dec.bos;
		for (i = rt->rt_labels - 1; i >= 0; i--) {
			hdr[i] = mpls_entry_encode(rt->rt_label[i], dec.ttl, 0, bos);
			bos = false;
		}
	}

	err = neigh_xmit(rt->rt_via_table, out_dev, rt->rt_via, skb);
	if (err)
		net_dbg_ratelimited("%s: packet transmission failed: %d\n",
				    __func__, err);
	return 0;

drop:
//.........这里部分代码省略.........

static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
{
	struct net_bridge_port *port = rcu_dereference(dev->br_port);

	return port ? &port->br->fake_rtable : NULL;
}

//.........这里部分代码省略.........
	/* If packet is coming from IRC server */
	if (dir == IP_CT_DIR_REPLY)
		return NF_ACCEPT;

	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
		return NF_ACCEPT;

	/* Not a full tcp header? */
	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	/* No data? */
	dataoff = protoff + th->doff*4;
	if (dataoff >= skb->len)
		return NF_ACCEPT;

	spin_lock_bh(&irc_buffer_lock);
	ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
				    irc_buffer);
	BUG_ON(ib_ptr == NULL);

	data = ib_ptr;
	data_limit = ib_ptr + skb->len - dataoff;

	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
	 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
	while (data < data_limit - (19 + MINMATCHLEN)) {
		if (memcmp(data, "\1DCC ", 5)) {
			data++;
			continue;
		}
		data += 5;
		/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */

		iph = ip_hdr(skb);
		pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
			 &iph->saddr, ntohs(th->source),
			 &iph->daddr, ntohs(th->dest));

		for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
			if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
				/* no match */
				continue;
			}
			data += strlen(dccprotos[i]);
			pr_debug("DCC %s detected\n", dccprotos[i]);

			/* we have at least
			 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
			 * data left (== 14/13 bytes) */
			if (parse_dcc((char *)data, data_limit, &dcc_ip,
				       &dcc_port, &addr_beg_p, &addr_end_p)) {
				pr_debug("unable to parse dcc command\n");
				continue;
			}
			pr_debug("DCC bound ip/port: %pI4:%u\n",
				&dcc_ip, dcc_port);

			/* dcc_ip can be the internal OR external (NAT'ed) IP */
			tuple = &ct->tuplehash[dir].tuple;
			if (tuple->src.u3.ip != htonl(dcc_ip) &&
			    tuple->dst.u3.ip != htonl(dcc_ip)) {
				if (net_ratelimit())
					printk(KERN_WARNING
						"Forged DCC command from %pI4: %pI4:%u\n",
						&tuple->src.u3.ip,
						&dcc_ip, dcc_port);
				continue;
			}

			exp = nf_conntrack_expect_alloc(ct);
			if (exp == NULL) {
				ret = NF_DROP;
				goto out;
			}
			tuple = &ct->tuplehash[!dir].tuple;
			port = htons(dcc_port);
			nf_conntrack_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
						 tuple->src.l3num,
						 NULL, &tuple->dst.u3,
						 IPPROTO_TCP, NULL, &port);

			nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
			if (nf_nat_irc && ct->status & IPS_NAT_MASK)
				ret = nf_nat_irc(skb, ctinfo,
						 addr_beg_p - ib_ptr,
						 addr_end_p - addr_beg_p,
						 exp);
			else if (nf_conntrack_expect_related(exp) != 0)
				ret = NF_DROP;
			nf_conntrack_expect_put(exp);
			goto out;
		}
	}
 out:
	spin_unlock_bh(&irc_buffer_lock);
	return ret;
}

static int netdev_open(struct net_device *pnetdev)
{
	uint status;	
	_adapter *padapter = (_adapter *)rtw_netdev_priv(pnetdev);
	struct pwrctrl_priv *pwrctrlpriv = &padapter->pwrctrlpriv;

	RT_TRACE(_module_os_intfs_c_,_drv_info_,("+871x_drv - dev_open\n"));
	DBG_8192C("+871x_drv - drv_open, bup=%d\n", padapter->bup);

	if(pwrctrlpriv->ps_flag == _TRUE){
		padapter->net_closed = _FALSE;
		goto netdev_open_normal_process;
	}
		
	if(padapter->bup == _FALSE)
    	{    
		padapter->bDriverStopped = _FALSE;
	 	padapter->bSurpriseRemoved = _FALSE;	 
		padapter->bCardDisableWOHSM = _FALSE;        	
	
		status = rtw_hal_init(padapter);		
		if (status ==_FAIL)
		{			
			RT_TRACE(_module_os_intfs_c_,_drv_err_,("rtl871x_hal_init(): Can't init h/w!\n"));
			goto netdev_open_error;
		}
		
		DBG_8192C("MAC Address = "MAC_FMT"\n", MAC_ARG(pnetdev->dev_addr));

		
		status=rtw_start_drv_threads(padapter);
		if(status ==_FAIL)
		{			
			RT_TRACE(_module_os_intfs_c_,_drv_err_,("Initialize driver software resource Failed!\n"));			
			goto netdev_open_error;			
		}


		if (init_hw_mlme_ext(padapter) == _FAIL)
		{
			RT_TRACE(_module_os_intfs_c_,_drv_err_,("can't init mlme_ext_priv\n"));
			goto netdev_open_error;
		}


#ifdef CONFIG_DRVEXT_MODULE
		init_drvext(padapter);
#endif

		if(padapter->intf_start)
		{
			padapter->intf_start(padapter);
		}

#ifdef CONFIG_PROC_DEBUG
#ifndef RTK_DMP_PLATFORM
		rtw_proc_init_one(pnetdev);
#endif
#endif

		rtw_led_control(padapter, LED_CTL_NO_LINK);

		padapter->bup = _TRUE;
	}
	padapter->net_closed = _FALSE;

	_set_timer(&padapter->mlmepriv.dynamic_chk_timer, 2000);

	if(( pwrctrlpriv->power_mgnt != PS_MODE_ACTIVE ) ||(padapter->pwrctrlpriv.bHWPwrPindetect))
	{
		padapter->pwrctrlpriv.bips_processing = _FALSE;	
		rtw_set_pwr_state_check_timer(&padapter->pwrctrlpriv);
 	}

	//netif_carrier_on(pnetdev);//call this func when rtw_joinbss_event_callback return success       
 	if(!netif_queue_stopped(pnetdev))
      		netif_start_queue(pnetdev);
	else
		netif_wake_queue(pnetdev);

#ifdef CONFIG_BR_EXT

#if (LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 35))
	rcu_read_lock();
#endif	// (LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 35))

	//if(check_fwstate(pmlmepriv, WIFI_STATION_STATE|WIFI_ADHOC_STATE) == _TRUE)
	{
		//struct net_bridge	*br = pnetdev->br_port->br;//->dev->dev_addr;
#if (LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 35))
		if (pnetdev->br_port) 
#else   // (LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 35))
		if (rcu_dereference(padapter->pnetdev->rx_handler_data))
#endif  // (LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 35)) 
		{
			struct net_device *br_netdev;
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24))
			br_netdev = dev_get_by_name(CONFIG_BR_EXT_BRNAME);
#else	// (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24))
			struct net *devnet = NULL;
//.........这里部分代码省略.........

static inline int
help_out(struct sk_buff *skb, unsigned char *rb_ptr, unsigned int datalen,
                struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	struct ip_ct_rtsp_expect expinfo;
	
	int dir = CTINFO2DIR(ctinfo);   /* = IP_CT_DIR_ORIGINAL */
	//struct  tcphdr* tcph = (void*)iph + iph->ihl * 4;
	//uint    tcplen = pktlen - iph->ihl * 4;
	char*   pdata = rb_ptr;
	//uint    datalen = tcplen - tcph->doff * 4;
	uint    dataoff = 0;
	int ret = NF_ACCEPT;
	
	struct nf_conntrack_expect *exp;
	
	__be16 be_loport;
	
	typeof(nf_nat_rtsp_hook) nf_nat_rtsp;

	memset(&expinfo, 0, sizeof(expinfo));
	
	while (dataoff < datalen) {
		uint    cmdoff = dataoff;
		uint    hdrsoff = 0;
		uint    hdrslen = 0;
		uint    cseqoff = 0;
		uint    cseqlen = 0;
		uint    transoff = 0;
		uint    translen = 0;
		uint    off;
		
		if (!rtsp_parse_message(pdata, datalen, &dataoff,
					&hdrsoff, &hdrslen,
					&cseqoff, &cseqlen,
					&transoff, &translen))
			break;      /* not a valid message */
		
		if (strncmp(pdata+cmdoff, "SETUP ", 6) != 0)
			continue;   /* not a SETUP message */
		pr_debug("found a setup message\n");

		off = 0;
		if(translen) {
			rtsp_parse_transport(pdata+transoff, translen, &expinfo);
		}

		if (expinfo.loport == 0) {
			pr_debug("no udp transports found\n");
			continue;   /* no udp transports found */
		}

		pr_debug("udp transport found, ports=(%d,%hu,%hu)\n",
		       (int)expinfo.pbtype, expinfo.loport, expinfo.hiport);

		exp = nf_ct_expect_alloc(ct);
		if (!exp) {
			ret = NF_DROP;
			goto out;
		}

		be_loport = htons(expinfo.loport);

		nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			/* media stream source can be different from the RTSP server address */
			// &ct->tuplehash[!dir].tuple.src.u3, &ct->tuplehash[!dir].tuple.dst.u3,
			NULL, &ct->tuplehash[!dir].tuple.dst.u3,
			IPPROTO_UDP, NULL, &be_loport); 

		exp->master = ct;

		exp->expectfn = expected;
		exp->flags = 0;

		if (expinfo.pbtype == pb_range) {
			pr_debug("Changing expectation mask to handle multiple ports\n");
			//exp->mask.dst.u.udp.port  = 0xfffe;
		}

		pr_debug("expect_related %pI4:%u-%pI4:%u\n",
		       &exp->tuple.src.u3.ip,
		       ntohs(exp->tuple.src.u.udp.port),
		       &exp->tuple.dst.u3.ip,
		       ntohs(exp->tuple.dst.u.udp.port));

		nf_nat_rtsp = rcu_dereference(nf_nat_rtsp_hook);
		if (nf_nat_rtsp && ct->status & IPS_NAT_MASK)
			/* pass the request off to the nat helper */
			ret = nf_nat_rtsp(skb, ctinfo, hdrsoff, hdrslen, &expinfo, exp);
		else if (nf_ct_expect_related(exp) != 0) {
			pr_info("nf_conntrack_expect_related failed\n");
			ret  = NF_DROP;
		}
		nf_ct_expect_put(exp);
		goto out;
	}
out:

	return ret;
}

/* log handler for internal netfilter logging api */
void
nfulnl_log_packet(struct net *net,
		  u_int8_t pf,
		  unsigned int hooknum,
		  const struct sk_buff *skb,
		  const struct net_device *in,
		  const struct net_device *out,
		  const struct nf_loginfo *li_user,
		  const char *prefix)
{
	size_t size;
	unsigned int data_len;
	struct nfulnl_instance *inst;
	const struct nf_loginfo *li;
	unsigned int qthreshold;
	unsigned int plen;
	struct nfnl_log_net *log = nfnl_log_pernet(net);
	const struct nfnl_ct_hook *nfnl_ct = NULL;
	struct nf_conn *ct = NULL;
	enum ip_conntrack_info uninitialized_var(ctinfo);

	if (li_user && li_user->type == NF_LOG_TYPE_ULOG)
		li = li_user;
	else
		li = &default_loginfo;

	inst = instance_lookup_get(log, li->u.ulog.group);
	if (!inst)
		return;

	plen = 0;
	if (prefix)
		plen = strlen(prefix) + 1;

	/* FIXME: do we want to make the size calculation conditional based on
	 * what is actually present?  way more branches and checks, but more
	 * memory efficient... */
	size =    nlmsg_total_size(sizeof(struct nfgenmsg))
		+ nla_total_size(sizeof(struct nfulnl_msg_packet_hdr))
		+ nla_total_size(sizeof(u_int32_t))	/* ifindex */
		+ nla_total_size(sizeof(u_int32_t))	/* ifindex */
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
		+ nla_total_size(sizeof(u_int32_t))	/* ifindex */
		+ nla_total_size(sizeof(u_int32_t))	/* ifindex */
#endif
		+ nla_total_size(sizeof(u_int32_t))	/* mark */
		+ nla_total_size(sizeof(u_int32_t))	/* uid */
		+ nla_total_size(sizeof(u_int32_t))	/* gid */
		+ nla_total_size(plen)			/* prefix */
		+ nla_total_size(sizeof(struct nfulnl_msg_packet_hw))
		+ nla_total_size(sizeof(struct nfulnl_msg_packet_timestamp))
		+ nla_total_size(sizeof(struct nfgenmsg));	/* NLMSG_DONE */

	if (in && skb_mac_header_was_set(skb)) {
		size +=   nla_total_size(skb->dev->hard_header_len)
			+ nla_total_size(sizeof(u_int16_t))	/* hwtype */
			+ nla_total_size(sizeof(u_int16_t));	/* hwlen */
	}

	spin_lock_bh(&inst->lock);

	if (inst->flags & NFULNL_CFG_F_SEQ)
		size += nla_total_size(sizeof(u_int32_t));
	if (inst->flags & NFULNL_CFG_F_SEQ_GLOBAL)
		size += nla_total_size(sizeof(u_int32_t));
	if (inst->flags & NFULNL_CFG_F_CONNTRACK) {
		nfnl_ct = rcu_dereference(nfnl_ct_hook);
		if (nfnl_ct != NULL) {
			ct = nfnl_ct->get_ct(skb, &ctinfo);
			if (ct != NULL)
				size += nfnl_ct->build_size(ct);
		}
	}

	qthreshold = inst->qthreshold;
	/* per-rule qthreshold overrides per-instance */
	if (li->u.ulog.qthreshold)
		if (qthreshold > li->u.ulog.qthreshold)
			qthreshold = li->u.ulog.qthreshold;


	switch (inst->copy_mode) {
	case NFULNL_COPY_META:
	case NFULNL_COPY_NONE:
		data_len = 0;
		break;

	case NFULNL_COPY_PACKET:
		if (inst->copy_range > skb->len)
			data_len = skb->len;
		else
			data_len = inst->copy_range;

		size += nla_total_size(data_len);
		break;

	case NFULNL_COPY_DISABLED:
	default:
		goto unlock_and_release;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	case PPTP_STOP_SESSION_REPLY:
		/* server confirms end of control session */
		if (info->sstate > PPTP_SESSION_STOPREQ)
			goto invalid;
		if (pptpReq->strep.resultCode == PPTP_STOP_OK)
			info->sstate = PPTP_SESSION_NONE;
		else
			info->sstate = PPTP_SESSION_ERROR;
		break;

	case PPTP_OUT_CALL_REPLY:
		/* server accepted call, we now expect GRE frames */
		if (info->sstate != PPTP_SESSION_CONFIRMED)
			goto invalid;
		if (info->cstate != PPTP_CALL_OUT_REQ &&
		    info->cstate != PPTP_CALL_OUT_CONF)
			goto invalid;

		cid = pptpReq->ocack.callID;
		pcid = pptpReq->ocack.peersCallID;
		if (info->pns_call_id != pcid)
			goto invalid;
		pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],
			 ntohs(cid), ntohs(pcid));

		if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
			info->cstate = PPTP_CALL_OUT_CONF;
			info->pac_call_id = cid;
			exp_gre(ct, cid, pcid);
		} else
			info->cstate = PPTP_CALL_NONE;
		break;

	case PPTP_IN_CALL_REQUEST:
		/* server tells us about incoming call request */
		if (info->sstate != PPTP_SESSION_CONFIRMED)
			goto invalid;

		cid = pptpReq->icreq.callID;
		pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
		info->cstate = PPTP_CALL_IN_REQ;
		info->pac_call_id = cid;
		break;

	case PPTP_IN_CALL_CONNECT:
		/* server tells us about incoming call established */
		if (info->sstate != PPTP_SESSION_CONFIRMED)
			goto invalid;
		if (info->cstate != PPTP_CALL_IN_REP &&
		    info->cstate != PPTP_CALL_IN_CONF)
			goto invalid;

		pcid = pptpReq->iccon.peersCallID;
		cid = info->pac_call_id;

		if (info->pns_call_id != pcid)
			goto invalid;

		pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
		info->cstate = PPTP_CALL_IN_CONF;

		/* we expect a GRE connection from PAC to PNS */
		exp_gre(ct, cid, pcid);
		break;

	case PPTP_CALL_DISCONNECT_NOTIFY:
		/* server confirms disconnect */
		cid = pptpReq->disc.callID;
		pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
		info->cstate = PPTP_CALL_NONE;

		/* untrack this call id, unexpect GRE packets */
		pptp_destroy_siblings(ct);
		break;

	case PPTP_WAN_ERROR_NOTIFY:
	case PPTP_SET_LINK_INFO:
	case PPTP_ECHO_REQUEST:
	case PPTP_ECHO_REPLY:
		/* I don't have to explain these ;) */
		break;

	default:
		goto invalid;
	}

	nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound);
	if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK)
		return nf_nat_pptp_inbound(skb, ct, ctinfo,
					   protoff, ctlh, pptpReq);
	return NF_ACCEPT;

invalid:
	pr_debug("invalid %s: type=%d cid=%u pcid=%u "
		 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
		 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
		 msg, ntohs(cid), ntohs(pcid),  info->cstate, info->sstate,
		 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
	return NF_ACCEPT;
}

static int ip_local_deliver_finish(struct sk_buff *skb)
{
	struct net *net = dev_net(skb->dev);

	__skb_pull(skb, ip_hdrlen(skb));

	/* Point into the IP datagram, just past the header. */
	skb_reset_transport_header(skb);

	rcu_read_lock();
	{
		int protocol = ip_hdr(skb)->protocol;
		int hash, raw;
		struct net_protocol *ipprot;

	resubmit:
		raw = raw_local_deliver(skb, protocol);

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

			if (!net_eq(net, &init_net) && !ipprot->netns_ok) {
				if (net_ratelimit())
					printk("%s: proto %d isn't netns-ready\n",
						__func__, protocol);
				kfree_skb(skb);
				goto out;
			}

			if (!ipprot->no_policy) {
				if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
					kfree_skb(skb);
					goto out;
				}
				nf_reset(skb);
			}
			ret = ipprot->handler(skb);
			if (ret < 0) {
				protocol = -ret;
				goto resubmit;
			}
			IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
		} else {
			if (!raw) {
				if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
					IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
					icmp_send(skb, ICMP_DEST_UNREACH,
						  ICMP_PROT_UNREACH, 0);
				}
			} else
				IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
			kfree_skb(skb);
		}
	}
 out:
	rcu_read_unlock();

	return 0;
}

static inline int
pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff,
		  struct PptpControlHeader *ctlh,
		  union pptp_ctrl_union *pptpReq,
		  unsigned int reqlen,
		  struct nf_conn *ct,
		  enum ip_conntrack_info ctinfo)
{
	struct nf_ct_pptp_master *info = nfct_help_data(ct);
	u_int16_t msg;
	__be16 cid = 0, pcid = 0;
	typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound;

	msg = ntohs(ctlh->messageType);
	pr_debug("outbound control message %s\n", pptp_msg_name[msg]);

	switch (msg) {
	case PPTP_START_SESSION_REQUEST:
		/* client requests for new control session */
		if (info->sstate != PPTP_SESSION_NONE)
			goto invalid;
		info->sstate = PPTP_SESSION_REQUESTED;
		break;

	case PPTP_STOP_SESSION_REQUEST:
		/* client requests end of control session */
		info->sstate = PPTP_SESSION_STOPREQ;
		break;

	case PPTP_OUT_CALL_REQUEST:
		/* client initiating connection to server */
		if (info->sstate != PPTP_SESSION_CONFIRMED)
			goto invalid;
		info->cstate = PPTP_CALL_OUT_REQ;
		/* track PNS call id */
		cid = pptpReq->ocreq.callID;
		pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
		info->pns_call_id = cid;
		break;

	case PPTP_IN_CALL_REPLY:
		/* client answers incoming call */
		if (info->cstate != PPTP_CALL_IN_REQ &&
		    info->cstate != PPTP_CALL_IN_REP)
			goto invalid;

		cid = pptpReq->icack.callID;
		pcid = pptpReq->icack.peersCallID;
		if (info->pac_call_id != pcid)
			goto invalid;
		pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],
			 ntohs(cid), ntohs(pcid));

		if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
			/* part two of the three-way handshake */
			info->cstate = PPTP_CALL_IN_REP;
			info->pns_call_id = cid;
		} else
			info->cstate = PPTP_CALL_NONE;
		break;

	case PPTP_CALL_CLEAR_REQUEST:
		/* client requests hangup of call */
		if (info->sstate != PPTP_SESSION_CONFIRMED)
			goto invalid;
		/* FUTURE: iterate over all calls and check if
		 * call ID is valid.  We don't do this without newnat,
		 * because we only know about last call */
		info->cstate = PPTP_CALL_CLEAR_REQ;
		break;

	case PPTP_SET_LINK_INFO:
	case PPTP_ECHO_REQUEST:
	case PPTP_ECHO_REPLY:
		/* I don't have to explain these ;) */
		break;

	default:
		goto invalid;
	}

	nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound);
	if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK)
		return nf_nat_pptp_outbound(skb, ct, ctinfo,
					    protoff, ctlh, pptpReq);
	return NF_ACCEPT;

invalid:
	pr_debug("invalid %s: type=%d cid=%u pcid=%u "
		 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
		 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
		 msg, ntohs(cid), ntohs(pcid),  info->cstate, info->sstate,
		 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
	return NF_ACCEPT;
}