跟一下wpa_supplicant(3-1) connect AP

转： http://blog.chinaunix.net/uid-20514606-id-3260316.html

WPA-PSK连接

从packages\apps\Settings\src\com\android\settings\wifi\WifiSettings.java
  和 WifiDialog.java 开始
1.
如果你点中某个AP
=> onClick执行 (WifiSettings.java)
   代码如下:

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1. button == WifiDialog.BUTTON_SUBMIT
   
2.    WifiConfiguration config = mDialog.getConfig();(WifiDialog.java中)
   
3.    WifiDialog getConfig => ( 因为才你自己选的某个AP 有网络ID,
   
4.                              所以network id !=-1,mSelected!=null)
   
5.    if (config.networkId != -1) {
   
6.         if (mSelected != null) { /* 走到这里 */
   
7.        /*下面函数 到2.分支继续分析 */
   
8.               mWifiManager.updateNetwork(config);
   
9.               /*下面函数 到4.分支继续分析 */
   
10.               saveNetworks();
    
11.         }
    
12.     } else {
    
13.         int networkId = mWifiManager.addNetwork(config);
    
14.         if (networkId != -1) {
    
15.             mWifiManager.enableNetwork(networkId, false);
    
16.             config.networkId = networkId;
    
17.             if (mDialog.edit || requireKeyStore(config)) {
    
18.                saveNetworks();
    
19.             } else {
    
20.                connect(networkId);
    
21.             }
    
22.          }
    
23.     }

2. 接上面分支1.的 mWifiManager.updateNetwork(config); 继续分析
=> addOrUpdateNetwork (wifiManager.java)
   ==> mService.addOrUpdateNetwork(config);
       (wifi manager 对wifi service function 的访问)
       ===> mWifiStateTracker.addNetwork() 
            ====> WifiNative.addNetworkCommand();
           (上面这句执行完成到 setVariables: 部分 ,分支3.继续)
           =====> JNI 执行 doIntCommand("ADD_NETWORK");
      上面是andorid ,下面就执行 wpa_cli的命令
      ---------------------------------------------------------
=> wpa_supplicant_ctrl_iface_add_network
   ==> wpa_config_add_network 
       ===> wpa_config_update_prio_list 
            更新 wpa prioty list! 就是conf文件设置的priority 组
看下解释:
# priority: Priority group
# By default, all networks and credentials get the same priority group
# (0). This field can be used to give higher priority for credentials
# (and similarly in struct wpa_ssid for network blocks) to change the
# Interworking automatic networking selection behavior. The matching
# network (based on either an enabled network block or a credential)
# with the highest priority value will be selected.

   ==> wpas_notify_network_added(wpa_s,
           ssid);  (dbus 部分,没有用)
   ==> wpa_config_set_network_defaults ,设置network(ssid) 如下default 值:
        #define DEFAULT_EAP_WORKAROUND ((unsigned int) -1)
        #define DEFAULT_EAPOL_FLAGS (EAPOL_FLAG_REQUIRE_KEY_UNICAST | \
           EAPOL_FLAG_REQUIRE_KEY_BROADCAST)
        #define DEFAULT_PROTO (WPA_PROTO_WPA | WPA_PROTO_RSN)
        #define DEFAULT_KEY_MGMT (WPA_KEY_MGMT_PSK | WPA_KEY_MGMT_IEEE8021X)
        #define DEFAULT_PAIRWISE (WPA_CIPHER_CCMP | WPA_CIPHER_TKIP)
        #define DEFAULT_GROUP (WPA_CIPHER_CCMP | WPA_CIPHER_TKIP | \
                 WPA_CIPHER_WEP104 | WPA_CIPHER_WEP40)
        #define DEFAULT_FRAGMENT_SIZE 1398
        就是加密算法,密钥管理,及EAPOL等等,struct wpa_ssid结构中注释很全
 android 发起的一条ADD_NETWORK命令完成了!

3. 又回到java,刚才2.分支中mService.addOrUpdateNetwork部分
=> mService.addOrUpdateNetwork(config);继续往下执行代码如下:
   setVariables: { 设置网络变量如下
   ==> mWifiStateTracker.setNetworkVariable(netId,  
      WifiConfiguration.ssidVarName,  config.SSID)  
        debugmessage:  CTRL_IFACE: SET_NETWORK id=0 name='ssid'
      ===> WifiNative.setNetworkVariableCommand(netId, name, value);
            (这中间还JNI部分,最后总是到 wpa_cli 执行set network命令) 
    ====>到 wpa_supplicant wpa_supplicant_ctrl_iface_set_network 
         =====> wpa_config_set(ssid, name, value, 0) 更新ssid_fields
                =====> wpa_config_update_psk 更新 wpa-psk的密码 
        /* 密码由SHA1 生成psk */
                =====> wpa_config_update_prio_list 更新prioty
               根据命令set network 命令参数内容:
       <network id> <variable name> <value>
      如果variable name 还会再设置prioty,
      就是说,除了conf文件1开始设置好,后面根据命令也还可以变
      你可以在java 中自己临时改变network 部分的 priority 
      wpa_cli完成后,下面又返回java

      ===> mWifiStateTracker.setNetworkVariable(netId, 
              WifiConfiguration.KeyMgmt.varName, allowedKeyManagementString)
       debugmessage: CTRL_IFACE: SET_NETWORK id=0 name='key_mgmt'
       一看就知道设置id=0 的netword 的key manager 变量

      ===> mWifiStateTracker.setNetworkVariable( netId,
               WifiConfiguration.priorityVarName, 
                  Integer.toString(config.priority)
        会跑到刚才说的wpa_config_update_prio_list,

   ==> mWifiManager.enableNetwork(networkId, false);
       ==> mWifiStateTracker.enableNetwork(netId, false); 
           ===> enableNetworkCommand(netId, false);
         ====> 到 wpa_cli 的 ENABLE_NETWORK 处理部分
        wpa_supplicant_ctrl_iface_enable_network 
            (dbgmessage: CTRL_IFACE: ENABLE_NETWORK id=0)
        =====> wpa_supplicant_enable_network(wpa_s, ssid);
              第1次,if (wpa_s->current_ssid == NULL) 满足
                            1. wpa_supplicant_req_sched_scan
               请求dirver 进行周期scan 
       (wpa_driver_nl80211_sched_scan NL80211_CMD_START_SCHED_SCAN)
                     scan paramater 比如ssids,filter_ssids
       基本来自于将conf文件读到内存的wpa_s->conf
       带着参数调用 wpa_supplicant_start_sched_scan
       去执行nl80211 driver 的 sched_scan

                            2. wpa_supplicant_req_scan(wpa_s, 2, 0);  
          到eloop_register_timeout(sec, usec,
             wpa_supplicant_scan, wpa_s, NULL);
                      2秒后  
        wpa_driver_nl80211_scan通过NL80211_CMD_TRIGGER_SCAN命令
                以及给定参数触发1个新的scan
                  wpa_supplicant_trigger_scan
      wpa_drv_scan 到nl80211 driver 的 scan2
kerneldoc :  http://linuxwireless.org/en/developers/Documentation/nl80211/kerneldoc
解释如下:
 NL80211_CMD_START_SCHED_SCAN: 
  start a scheduled scan at certain intervals, as specified by NL80211_ATTR_SCHED_SCAN_INTERVAL. Like with normal scans, 
  if SSIDs (NL80211_ATTR_SCAN_SSIDS) are passed, they are used in the probe requests. For broadcast, 
  a broadcast SSID must be passed (ie. an empty string). If no SSID is passed, 
  no probe requests are sent and a passive scan is performed. NL80211_ATTR_SCAN_FREQUENCIES,
  if passed, define which channels should be scanned; if not passed, all channels allowed for the current regulatory domain are used.
  Extra IEs can also be passed from the userspace by using the NL80211_ATTR_IE attribute
  上面的意思就是让STA driver开始1个在sched scan interval 时间间隔的scan,
  如果有已经设置的网络,就发probe request,如果没有那么执行
  被动扫描(接收AP的beacon), 并根据设置的通道梳洗来判断,scan 所有channel
  还是某些

NL80211_CMD_TRIGGER_SCAN
  trigger a new scan with the given parameters NL80211_ATTR_TX_NO_CCK_RATE is
  used to decide whether to send the probe requests at CCK rate or not.

  wpa_supplicant_req_sched_scan   wpa_supplicant_req_scan 区别:
  就是 sched_scan 和scan2的区别 请看代码中的注释
         /**
  * scan2 - Request the driver to initiate scan
  * @priv: private driver interface data
  * @params: Scan parameters
  *
  * Returns: 0 on success, -1 on failure
  *
  * Once the scan results are ready, the driver should report scan
  * results event for wpa_supplicant which will eventually request the
  * results with wpa_driver_get_scan_results2().
  */

         /**
  * sched_scan - Request the driver to initiate scheduled scan
  * @priv: private driver interface data
  * @params: Scan parameters
  * @interval: interval between scan cycles
  *
  * Returns: 0 on success, -1 on failure
  *
  * This operation should be used for scheduled scan offload to
  * the hardware.  Every time scan results are available, the
  * driver should report scan results event for wpa_supplicant
  * which will eventually request the results with
  * wpa_driver_get_scan_results2().  This operation is optional
  * and if not provided or if it returns -1, we fall back to
  * normal host-scheduled scans.
  */
  sched scan 就是所启动一个定时扫描循环,然后scan2 触发一个scan,
  这样driver 就在scan2 后按时间间隔循环scan

      接下来到4.分支继续
  
到这里已经是连接上AP后的处理部分了
=> saveNetworks(); (wifisettings.java)
   ==> enableNetworks();  (loop mAccessPoints.getPreferenceCount )
   ==> mWifiManager.saveConfiguration();
       能看到如下message 表示在保存建立连接的network设置
       Writing configuration file '/data/misc/wifi/wpa_supplicant.conf'
       ===>mService.saveConfiguration
            ====> mWifiStateTracker.saveConfig 
           =====> wpa_cli AP_SCAN 1 + wpa_cli SAVE_CONFIG
            ====> mWifiStateTracker.reloadConfig 
     ------------------------------------------
           wpa_cli RECONFIGURE 命令
                  =====> wpa_supplicant_reload_configuration(), message 如下:

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1. D/wpa_supplicant( 2129): Reading configuration file '/data/misc/wifi/wpa_supplicant.conf'
   
2. D/wpa_supplicant( 2129): ctrl_interface='wlan0:0'
   
3.                   wpa_config_read, wpa_config_process_global
   
4. D/wpa_supplicant( 2129): update_config=1
   
5.                   wpa_config_read, wpa_config_process_global
   
6. D/wpa_supplicant( 2129): Line: 5 - start of a new network block
   
7.                   wpa_config_read ,wpa_config_read_network
   
8. D/wpa_supplicant( 2129): key_mgmt: 0x2
   
9. D/wpa_supplicant( 2129): priority=1 (0x1)
   
10. D/wpa_supplicant( 2129): Priority group 1 
    
11.                 wpa_config_read ,wpa_config_debug_dump_networks
    
12. D/wpa_supplicant( 2129): id=0 ssid='RD-Test

  
                wpa_config_read ,wpa_config_debug_dump_networks

                  =====> wpa_sm_set_config(wpa_s->wpa, NULL); 
        wpa 状态机 init,并将config 中相关内容设置到wpa状态机

                  =====> wpa_supplicant_update_config 的 message :
D/wpa_supplicant( 2129): WPS: Set UUID for interface wlan0  
                     对应  wpa_supplicant_update_config ,wpas_wps_set_uuid

D/wpa_supplicant( 2129): wlan0: P2P: Intra BSS distribution enabled
V/WifiMonitor( 1363): Event [CTRL-EVENT-STATE-CHANGE id=-1 state=0 BSSID=00:00:00:00:00:00]
V/WifiStateTracker( 1363): Changing supplicant state: SCANNING ==> DISCONNECTED
D/wpa_supplicant( 2129): Setting scan request: 2 sec 0 usec
D/wpa_supplicant( 2129): Reconfiguration completed

                  =====> wpa_supplicant_clear_status !
            ----------------------------------------------
     又回到java 
            ====> boardcast  NETWORK_IDS_CHANGED_ACTION
   ==> updateAccessPoints();

上面 mWifiManager.enableNetwork(networkId, false); 
       => WifiNative.enableNetworkCommand 发 ENABLE_NETWORK命令
          ==> wpa_supplicant_ctrl_iface_enable_network
       ===> wpa_supplicant_enable_network
           ===> 继续scan

 

4. 接上面3.分支继续
这时你会看到driver的消息:
 Association completed. (bss_info_changed)
字面上看关联成功? 还没发requet associate ?

那么在那里发的request associate ?
前面3.分支,开始我们SET_NETWORK,之后我们又ENABLE_NETWORK
最后发起对我们选择的AP,进行scan2,scan之后就需要等待接收结果

在前面wap_supplicant init 部分
曾经做过这个动作 wpa_driver_nl80211_init_nl
该函数最后调用:
eloop_register_read_sock(nl_socket_get_fd(drv->nl_handle_event),
     wpa_driver_nl80211_event_receive, drv,
     drv->nl_handle_event);
前面解释过是用来接收scan result,mlme,regulator 相关的多播包
其实前面wifi eanalbe 时这部分应该也做,并且如果conf中有Network
它也会去pick network,然后开始连接过程,
现在你是第1次手动连接,同样也是从scan result 中
找到你选择的那个AP,进行连接,看下面:

=>wpa_driver_nl80211_event_receive
通过process_event callback 来继续处理 NL80211_CMD_NEW_SCAN_RESULTS 如下:
这时先会 eloop_cancel_timeout(wpa_driver_nl80211_scan_timeout,
取消前面的10s scan timeout eloop 
   ==> send_scan_event 
       ===> wpa_supplicant_event(drv->ctx, EVENT_SCAN_RESULTS, &event);
            ====> wpa_supplicant_event_scan_results
                 =====> _wpa_supplicant_event_scan_results
                       ======>wpas_notify_scan_results(wpa_s); 
                =======> wpas_wps_notify_scan_results
                "Event [WPS-AP-AVAILABLE]"
                       ======> wpa_supplicant_pick_network
                从scan results 中选择AP,
                     根据scan 到的new ap 去匹配 (有prori等)

        其中执行 wpa_supplicant_select_bss
          可以看到: Selecting BSS from priority group 1:
                             wpa_supplicant_pick_network最后返回一个
        struct wpa_bss 结构的pointer,包含该AP的info
                       
                       ======> wpa_supplicant_rsn_preauth_scan_results
                  对scan results 启动预身份验证
    注意 WPA 不支持预先身份验证,WPA2才支持
                ======> wpa_supplicant_connect 开始连接AP
终于要开始连接了,这是应该会看到下面的msg:
wlan0: Request association: reassociate: 1  
       selected: 00:1f:33:b9:5d:e0  
       bssid: 00:00:00:00:00:00  
       pending: 00:00:00:00:00:00  
       wpa_state: SCANNING

wpa_supplicant_connect 去调用
=======> wpa_supplicant_associate(wpa_s, selected, ssid);
         ========> sme_authenticate(struct wpa_supplicant *wpa_s,
                     struct wpa_bss *bss, struct wpa_ssid *ssid)
                   开始设置一堆参数为driver层auth 调用做准备
     就提下params.auth_alg = WPA_AUTH_ALG_OPEN;
     其他看代码
     /* WPA 802.11 author 使用OPEN !!! */
                   =========>wpa_supplicant_set_suites
                    (struct wpa_supplicant *wpa_s,
                    struct wpa_bss *bss, struct wpa_ssid *ssid,
      u8 *wpa_ie, size_t *wpa_ie_len)
              它设置认证和加密的参数,这些参数从
       这个AP scan result 发过的被处理后挂在
        struct wpa_bss 的最后的IE部分获得
         获得 WPA IE ,RSN IE 后就知道了,从message看:
WPA: Selected cipher suites: group WPA_CIPHER_TKIP, 
                             pairwise WPA_CIPHER_CCMP, 
        key_mgmt WPA_KEY_MGMT_PSK 
        proto WPA_PROTO_RSN
表示:
group 使用TKIP, 成对密钥 使用CCMP, key manager wpa_psk,
协议为RSN ,就是强健安全网络(RSN)的标准
                            调用两次wpa_sm_set_param
                            设置proto,proto enanble 到 wpa state machine结构
       struct wpa_sm 的,proto 和 rsn_enabled
                            
       还在wpa_supplicant_set_suites中,接下来通过
       wpa_sm_set_assoc_wpa_ie_default去生成关联需要
       的WPA/RSN IE,放到struct wpa_sm->assoc_wpa_ie

                            最后 wpa_sm_set_pmk 将预共享密钥PSK,copy到
       struct wpa_sm->pmk,后面要用

                   =========> wpa_supplicant_cancel_sched_scan
                wpa_supplicant_cancel_scan
        开始认证时要取消sched scan ,并canle 当前scan

                   =========> wpa_msg(wpa_s, MSG_INFO, 
               "SME: Trying to authenticate with "
               MACSTR (SSID='%s' freq=%d MHz)", 
         MAC2STR(params.bssid),
        wpa_ssid_txt(params.ssid, params.ssid_len),
        params.freq);
                             对应可以看到WifiMonitor msg: 
                         Event [SME: Trying to authenticate with 00:1f:33:b9:5d:e0 
       (SSID='RD-Test' freq=2462 MHz)]
                             由wpa_supplicant_ctrl_iface_send发到
                             wifi monitor 被 parse 为 UNKNOWN,
        monitor 不关心

                    =========> wpa_supplicant_set_state(wpa_s, 
                                      WPA_AUTHENTICATING);
                    =========> wpa_s->new_connection = 1;
                    =========> wpa_drv_set_operstate(wpa_s, 0);
                 /* 设置到IF_OPER_DORMANT */
                    =========> wpa_supplicant_stop_bgscan 停止back groud scan
                    =========> wpas_notify_state_changed
          ==========> wpa_msg_ctrl(wpa_s, MSG_INFO, 
          WPA_EVENT_STATE_CHANGE 给wifi monitor 发:
           Event [SME: Trying to authenticate with 00:1f:33:b9:5d:e0 (SSID='RD-Test' 
    freq=2462 MHz)]

                    =========> wpa_supplicant_rsn_supp_set_config
        注释如下:
        Notify WPA state machine that configuration has changed

                      配置的网络上下文就是
        struct wpa_ssid - Network configuration data
        还有 PTK 生命周期

                    =========> wpa_supplicant_initiate_eapol
          配置EAPOL 状态机器, 启动 EAPOL,EAP 状态机器
                               调用 eapol_sm_notify_eap_success
          清除EAP success
                               调用 eapol_sm_notify_eap_fail
          清除 EAP failure

                                调用eapol_sm_notify_portControl(Auto)
    设置prot control 为自动,其他还有
    ForceUnauthorized, ForceAuthorized

       每个类似的eapol sm notify 函数中都
                     eapol_sm_step(sm); 这句很重要! 
       虽然简单,但却是状态机的驱动中枢!

                   =========>wpas_notify_network_changed
                   =========> wpa_drv_authenticate
               前面一大堆,为的就是这句,这数执行nl80211 driver
        authenticate,发出后等driver 响应
        到分支5.继续
               
                   =========>eloop_register_timeout(callback=>sme_auth_timer)
            认证超时失败处理

                   =========> eapol_sm_notify_portEnabled(wpa_s->eapol, FALSE);
                             eapol_sm_notify_portValid(wpa_s->eapol, FALSE);
        注释如下: 
/*
* Set portEnabled first to FALSE in order to get EAP state machine out
* of the SUCCESS state and eapSuccess cleared. Without this, EAPOL PAE
* state machine may transit to AUTHENTICATING state based on obsolete
* eapSuccess and then trigger BE_AUTH to SUCCESS and PAE to
* AUTHENTICATED without ever giving chance to EAP state machine to
* reset the state.
*/