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網絡子係統66_策略路由初始化
// 策略路由鏈表
// 係統中所有策略路由通過fib_rules鏈接在一起
static struct fib_rule default_rule = {
.r_clntref = ATOMIC_INIT(2),//引用計數
.r_preference = 0x7FFF,//路由規則優先級
.r_table = RT_TABLE_DEFAULT,//路由表標示符
.r_action = RTN_UNICAST,//路由類型，間接定義了當路由查找匹配時應采取的動作
};
static struct fib_rule main_rule = {
.r_next = &default_rule,
.r_clntref = ATOMIC_INIT(2),
.r_preference = 0x7FFE,
.r_table = RT_TABLE_MAIN,
.r_action = RTN_UNICAST,
};
static struct fib_rule local_rule = {
.r_next = &main_rule,
.r_clntref = ATOMIC_INIT(2),
.r_table = RT_TABLE_LOCAL,
.r_action = RTN_UNICAST,
};
static struct fib_rule *fib_rules = &local_rule;
// 策略路由初始化
// 向netdev_chain注冊監聽塊
// 調用路徑：ip_rt_init->ip_fib_init->fib_rules_init
2.1 void __init fib_rules_init(void)
{
register_netdevice_notifier(&fib_rules_notifier);
}
2.1 static struct notifier_block fib_rules_notifier = {
.notifier_call =fib_rules_event,
};
// 策略路由對設備事件的處理
// 隻處理設備注冊，注銷事件
static int fib_rules_event(struct notifier_block *this, unsigned long event, void *ptr)
{
struct net_device *dev = ptr;
//設備注銷，刪除與設備相關的策略路由
if (event == NETDEV_UNREGISTER)
fib_rules_detach(dev);
else if (event == NETDEV_REGISTER)
fib_rules_attach(dev);//添加與設備相關的策略
return NOTIFY_DONE;
}
// 禁止與設備相關的策略路由
// 將策略路由r_ifindex=-1，禁止策略路由
2.2 static void fib_rules_detach(struct net_device *dev)
{
struct fib_rule *r;
//遍曆係統中所有的策略路由
for (r=fib_rules; r; r=r->r_next) {
if (r->r_ifindex == dev->ifindex) {//策略路由使用的設備index
write_lock_bh(&fib_rules_lock);
r->r_ifindex = -1;//禁止該策略路由
write_unlock_bh(&fib_rules_lock);
}
}
}
// 激活設備的策略路由
// fib_rule->r_ifname表示策略應用的設備
2.3 static void fib_rules_attach(struct net_device *dev)
{
struct fib_rule *r;
for (r=fib_rules; r; r=r->r_next) {
if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0) {
write_lock_bh(&fib_rules_lock);
r->r_ifindex = dev->ifindex;
write_unlock_bh(&fib_rules_lock);
}
}
}
最後更新：2017-04-03 14:53:48