static int __init br_init(void)
{
int err;
br_stp_sap = llc_sap_open(LLC_SAP_BSPAN, br_stp_rcv);
if (!br_stp_sap) {
printk(KERN_ERR "bridge: can't register sap for STP\n");
return -EADDRINUSE;
}
br_fdb_init();
err = br_netfilter_init();
if (err)
goto err_out1;
err = register_netdevice_notifier(&br_device_notifier);
if (err)
goto err_out2;
br_netlink_init();
brioctl_set(br_ioctl_deviceless_stub);
br_handle_frame_hook = br_handle_frame;
br_fdb_get_hook = br_fdb_get;
br_fdb_put_hook = br_fdb_put;
return 0;
err_out2:
br_netfilter_fini();
err_out1:
llc_sap_put(br_stp_sap);
return err;
}
/**
* llc_sap_remove_socket - removes a socket from SAP
* @sap: SAP
* @sk: socket
*
* This function removes a connection from the hash tables of a SAP if
* the connection was in this list.
*/
void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
{
struct llc_sock *llc = llc_sk(sk);
spin_lock_bh(&sap->sk_lock);
sk_nulls_del_node_init_rcu(sk);
hlist_del(&llc->dev_hash_node);
sap->sk_count--;
spin_unlock_bh(&sap->sk_lock);
llc_sap_put(sap);
}
void stp_proto_unregister(const struct stp_proto *proto)
{
mutex_lock(&stp_proto_mutex);
if (is_zero_ether_addr(proto->group_address))
rcu_assign_pointer(stp_proto, NULL);
else
rcu_assign_pointer(garp_protos[proto->group_address[5] -
GARP_ADDR_MIN], NULL);
synchronize_rcu();
if (--sap_registered == 0)
llc_sap_put(sap);
mutex_unlock(&stp_proto_mutex);
}
static int __init br_init(void)
{
int err;
br_stp_sap = llc_sap_open(LLC_SAP_BSPAN, br_stp_rcv);
if (!br_stp_sap) {
printk(KERN_ERR "bridge: can't register sap for STP\n");
return -EADDRINUSE;
}
//网桥数据库初始化，分配slab缓冲区
err = br_fdb_init();
if (err)
goto err_out;
//netfilter钩子初始
err = br_netfilter_init();
if (err)
goto err_out1;
////在netdev_chain通知链表上注册
err = register_netdevice_notifier(&br_device_notifier);
if (err)
goto err_out2;
err = br_netlink_init();
if (err)
goto err_out3;
//设置ioctl钩子函数:br_ioctl_hook
//通过brctl addbr br0命令建立网桥，此处用户空间调用的brctl命令最终对应到内核中的br_ioctl_deviceless_stub处理函数
brioctl_set(br_ioctl_deviceless_stub);
//设置报文处理钩子函数
br_handle_frame_hook = br_handle_frame;
//网桥数据库处理钩子
br_fdb_get_hook = br_fdb_get;
br_fdb_put_hook = br_fdb_put;
return 0;
err_out3:
unregister_netdevice_notifier(&br_device_notifier);
err_out2:
br_netfilter_fini();
err_out1:
br_fdb_fini();
err_out:
llc_sap_put(br_stp_sap);
return err;
}
static void __exit br_deinit(void)
{
rcu_assign_pointer(br_stp_sap->rcv_func, NULL);
br_netlink_fini();
br_netfilter_fini();
unregister_netdevice_notifier(&br_device_notifier);
brioctl_set(NULL);
br_cleanup_bridges();
synchronize_net();
llc_sap_put(br_stp_sap);
br_fdb_get_hook = NULL;
br_fdb_put_hook = NULL;
br_handle_frame_hook = NULL;
br_fdb_fini();
}
/**
* llc_ui_autoport - provide dynamically allocate SAP number
*
* Provide the caller with a dynamically allocated SAP number according
* to the rules that are set in this function. Returns: 0, upon failure,
* SAP number otherwise.
*/
static int llc_ui_autoport(void)
{
struct llc_sap *sap;
int i, tries = 0;
while (tries < LLC_SAP_DYN_TRIES) {
for (i = llc_ui_sap_last_autoport;
i < LLC_SAP_DYN_STOP; i += 2) {
sap = llc_sap_find(i);
if (!sap) {
llc_ui_sap_last_autoport = i + 2;
goto out;
}
llc_sap_put(sap);
}
llc_ui_sap_last_autoport = LLC_SAP_DYN_START;
tries++;
}
i = 0;
out:
return i;
}
/**
* llc_rcv - 802.2 entry point from net lower layers
* @skb: received pdu
* @dev: device that receive pdu
* @pt: packet type
*
* When the system receives a 802.2 frame this function is called. It
* checks SAP and connection of received pdu and passes frame to
* llc_{station,sap,conn}_rcv for sending to proper state machine. If
* the frame is related to a busy connection (a connection is sending
* data now), it queues this frame in the connection's backlog.
*/
int llc_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
struct llc_sap *sap;
struct llc_pdu_sn *pdu;
int dest;
int (*rcv)(struct sk_buff *, struct net_device *,
struct packet_type *, struct net_device *);
void (*sta_handler)(struct sk_buff *skb);
void (*sap_handler)(struct llc_sap *sap, struct sk_buff *skb);
if (!net_eq(dev_net(dev), &init_net))
goto drop;
/*
* When the interface is in promisc. mode, drop all the crap that it
* receives, do not try to analyse it.
*/
if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
dprintk("%s: PACKET_OTHERHOST\n", __func__);
goto drop;
}
skb = skb_share_check(skb, GFP_ATOMIC);
if (unlikely(!skb))
goto out;
if (unlikely(!llc_fixup_skb(skb)))
goto drop;
pdu = llc_pdu_sn_hdr(skb);
if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
goto handle_station;
sap = llc_sap_find(pdu->dsap);
if (unlikely(!sap)) {/* unknown SAP */
dprintk("%s: llc_sap_find(%02X) failed!\n", __func__,
pdu->dsap);
goto drop;
}
/*
* First the upper layer protocols that don't need the full
* LLC functionality
*/
rcv = rcu_dereference(sap->rcv_func);
dest = llc_pdu_type(skb);
sap_handler = dest ? ACCESS_ONCE(llc_type_handlers[dest - 1]) : NULL;
if (unlikely(!sap_handler)) {
if (rcv)
rcv(skb, dev, pt, orig_dev);
else
kfree_skb(skb);
} else {
if (rcv) {
struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
if (cskb)
rcv(cskb, dev, pt, orig_dev);
}
sap_handler(sap, skb);
}
llc_sap_put(sap);
out:
return 0;
drop:
kfree_skb(skb);
goto out;
handle_station:
sta_handler = ACCESS_ONCE(llc_station_handler);
if (!sta_handler)
goto drop;
sta_handler(skb);
goto out;
}
void unregister_8022_client(struct datalink_proto *proto)
{
llc_sap_put(proto->sap);
kfree(proto);
}
