hostapd 中netlink初始化

1. 从main()中调用hostapd_driver_init() 

　　hostapd_driver_init(interfaces.iface[i])

netlink相关结构体

驱动结构体struct wpa_driver_ops函数注册

const struct wpa_driver_ops wpa_driver_nl80211_ops = {
.name = "nl80211",
.desc = "Linux nl80211/cfg80211",
.get_bssid = wpa_driver_nl80211_get_bssid,
.get_ssid = wpa_driver_nl80211_get_ssid,
.set_key = driver_nl80211_set_key,
.scan2 = driver_nl80211_scan2,
.sched_scan = wpa_driver_nl80211_sched_scan,
.stop_sched_scan = wpa_driver_nl80211_stop_sched_scan,
.get_scan_results2 = wpa_driver_nl80211_get_scan_results,
.abort_scan = wpa_driver_nl80211_abort_scan,
.deauthenticate = driver_nl80211_deauthenticate,
.authenticate = driver_nl80211_authenticate,
.associate = wpa_driver_nl80211_associate,
.global_init = nl80211_global_init,
.global_deinit = nl80211_global_deinit,
.init2 = wpa_driver_nl80211_init,
.deinit = driver_nl80211_deinit,
.get_capa = wpa_driver_nl80211_get_capa,
.set_operstate = wpa_driver_nl80211_set_operstate,
.set_supp_port = wpa_driver_nl80211_set_supp_port,
.set_country = wpa_driver_nl80211_set_country,
.get_country = wpa_driver_nl80211_get_country,
.set_ap = wpa_driver_nl80211_set_ap,
.set_acl = wpa_driver_nl80211_set_acl,
.if_add = wpa_driver_nl80211_if_add,
.if_remove = driver_nl80211_if_remove,
.send_mlme = driver_nl80211_send_mlme,
.get_hw_feature_data = nl80211_get_hw_feature_data,
.sta_add = wpa_driver_nl80211_sta_add,
.sta_remove = driver_nl80211_sta_remove,
.tx_control_port = nl80211_tx_control_port,
.hapd_send_eapol = wpa_driver_nl80211_hapd_send_eapol,
.sta_set_flags = wpa_driver_nl80211_sta_set_flags,
.sta_set_airtime_weight = driver_nl80211_sta_set_airtime_weight,
.hapd_init = i802_init,
.hapd_deinit = i802_deinit,
.set_wds_sta = i802_set_wds_sta,
.get_seqnum = i802_get_seqnum,
.flush = i802_flush,

......//还有很多

};　　

 netlink初始化

 调用netlink_init  进行 netlink初始化  global->netlink = netlink_init(cfg) 

netlink_init()

 （1）创建netlink套接字

协议族为PF_NETLINK

类型为原始套接字

协议为：NETLINK_ROUTE ，用户空间的路由守护程序之间的通讯通道，比如BGP,OSPF,RIP以及内核数据转发模块。用户态的路由守护程序通过此类型的协议来更新内核中的路由表。

（2）bind 将socket与对应的网络地址进行绑定

local.nl_family = AF_NETLINK;
local.nl_groups = RTMGRP_LINK;

Netlink的RTMGRP_LINK多播群组，用户空间程序可以注册netlink的RTMGRP_LINK多播群组，当设备的状态或配置发生变更时，就会用rtmsg_ifinfo把通知信息传送给Link多播群组RTMGRP_LINK。

（3）eloop_register_read_sock 注册 netlink_receive

• netlink_receive（）这个函数做了什么？
  • 接收来自对方主机传来的数据，在这里，MSG_DONTWAIT为0，也就是参数flags。

  •  cb函数的参数是啥呢？

  • cb函数 wpa_driver_nl80211_event_rtm_newlink(void *ctx, struct ifinfomsg *ifi, u8 *buf, size_t len)

  • 不知道这里为什么使用send? send是TCP的函数，recvfrom是udp的

  •   　　注册handler处理函数到table表中，type：EVENT_TYPE_READ

　　　　eloop_sock_table_add_sock函数

 　　　　eloop_sock_queue（）函数 ，这里选择梳理epoll事件处理（代码中有epoll和queue两种方式）

总结：

netlink 初始化 就是创建协议族为PF_NETLINK的socket，并将sock及对应的处理函数handle注册到eloop