（一百零六）Android O wpa_supplicant driver初始化
前言：之前在（一百零五）Android O 获取mac地址流程分析 中直接将driver_cmd等效于wpa_driver_nl80211_driver_cmd，流程其实有点缺失，本文补上这块。
jiatai@jiatai:~/expand/aosp/aosp/external/wpa_supplicant_8$ grep "wpa_driver_nl80211_driver_cmd" ./ -nr
./src/drivers/driver_nl80211.c:10432: .driver_cmd = wpa_driver_nl80211_driver_cmd,
1.driver初始化流程
之前在（一百零二）Android O wpa_supplicant初始化学习 提及驱动可以在init.rc中配置，比如在该文中配置项为-Dnl80211，那就表示是用nl80211的驱动，从代码层面看下是怎么影响driver_cmd的。
1.1 main.c
case 'D':
iface->driver = optarg;
break;
...
wpa_s = wpa_supplicant_add_iface(global, &ifaces[i], NULL);1.2 wpa_supplicant.c
/**
* wpa_supplicant_add_iface - Add a new network interface
* @global: Pointer to global data from wpa_supplicant_init()
* @iface: Interface configuration options
* @parent: Parent interface or %NULL to assign new interface as parent
* Returns: Pointer to the created interface or %NULL on failure
*
* This function is used to add new network interfaces for %wpa_supplicant.
* This can be called before wpa_supplicant_run() to add interfaces before the
* main event loop has been started. In addition, new interfaces can be added
* dynamically while %wpa_supplicant is already running. This could happen,
* e.g., when a hotplug network adapter is inserted.
*/
struct wpa_supplicant * wpa_supplicant_add_iface(struct wpa_global *global,
struct wpa_interface *iface,
struct wpa_supplicant *parent)
{
...
if (wpa_supplicant_init_iface(wpa_s, &t_iface)) {
wpa_printf(MSG_DEBUG, "Failed to add interface %s",
iface->ifname);
wpa_supplicant_deinit_iface(wpa_s, 0, 0);
return NULL;
}
...
static int wpa_supplicant_init_iface(struct wpa_supplicant *wpa_s,
struct wpa_interface *iface)
{
struct wpa_driver_capa capa;
int capa_res;
u8 dfs_domain;
wpa_printf(MSG_DEBUG, "Initializing interface '%s' conf '%s' driver "
"'%s' ctrl_interface '%s' bridge '%s'", iface->ifname,
iface->confname ? iface->confname : "N/A",
iface->driver ? iface->driver : "default",
iface->ctrl_interface ? iface->ctrl_interface : "N/A",
iface->bridge_ifname ? iface->bridge_ifname : "N/A");
...
/* Initialize driver interface and register driver event handler before
* L2 receive handler so that association events are processed before
* EAPOL-Key packets if both become available for the same select()
* call. */
if (wpas_init_driver(wpa_s, iface) < 0)
return -1;
...
static int wpas_init_driver(struct wpa_supplicant *wpa_s,
struct wpa_interface *iface)
{
const char *ifname, *driver, *rn;
driver = iface->driver;
next_driver:
if (wpa_supplicant_set_driver(wpa_s, driver) < 0)
return -1;
...
接着调用wpa_supplicant_set_driver，将驱动名称传进来，即之前说的nl80211
static int wpa_supplicant_set_driver(struct wpa_supplicant *wpa_s,
const char *name)
{
int i;
size_t len;
const char *pos, *driver = name;
if (wpa_s == NULL)
return -1;
if (wpa_drivers[0] == NULL) {
wpa_msg(wpa_s, MSG_ERROR, "No driver interfaces build into "
"wpa_supplicant");
return -1;
}
if (name == NULL) {
/* default to first driver in the list */
return select_driver(wpa_s, 0);
}
do {
pos = os_strchr(driver, ',');
if (pos)
len = pos - driver;
else
len = os_strlen(driver);
for (i = 0; wpa_drivers[i]; i++) {
if (os_strlen(wpa_drivers[i]->name) == len &&
os_strncmp(driver, wpa_drivers[i]->name, len) ==
0) {
/* First driver that succeeds wins */
if (select_driver(wpa_s, i) == 0)
return 0;
}
}
driver = pos + 1;
} while (pos);
wpa_msg(wpa_s, MSG_ERROR, "Unsupported driver '%s'", name);
return -1;
}对wpa_drivers中的驱动进行轮询看哪个是和传入的参数nl80211一样的。
1.3 drivers.c
这个文件列举了当前配置的驱动，我们一直说的nl80211就是第一个
const struct wpa_driver_ops *const wpa_drivers[] =
{
#ifdef CONFIG_DRIVER_NL80211
&wpa_driver_nl80211_ops,
#endif /* CONFIG_DRIVER_NL80211 */
#ifdef CONFIG_DRIVER_WEXT
&wpa_driver_wext_ops,
#endif /* CONFIG_DRIVER_WEXT */
#ifdef CONFIG_DRIVER_HOSTAP
&wpa_driver_hostap_ops,
#endif /* CONFIG_DRIVER_HOSTAP */
#ifdef CONFIG_DRIVER_BSD
&wpa_driver_bsd_ops,
#endif /* CONFIG_DRIVER_BSD */
#ifdef CONFIG_DRIVER_OPENBSD
&wpa_driver_openbsd_ops,
#endif /* CONFIG_DRIVER_OPENBSD */
#ifdef CONFIG_DRIVER_NDIS
&wpa_driver_ndis_ops,
#endif /* CONFIG_DRIVER_NDIS */
#ifdef CONFIG_DRIVER_WIRED
&wpa_driver_wired_ops,
#endif /* CONFIG_DRIVER_WIRED */
#ifdef CONFIG_DRIVER_MACSEC_LINUX
&wpa_driver_macsec_linux_ops,
#endif /* CONFIG_DRIVER_MACSEC_LINUX */
#ifdef CONFIG_DRIVER_MACSEC_QCA
&wpa_driver_macsec_qca_ops,
#endif /* CONFIG_DRIVER_MACSEC_QCA */
#ifdef CONFIG_DRIVER_ROBOSWITCH
&wpa_driver_roboswitch_ops,
#endif /* CONFIG_DRIVER_ROBOSWITCH */
#ifdef CONFIG_DRIVER_ATHEROS
&wpa_driver_atheros_ops,
#endif /* CONFIG_DRIVER_ATHEROS */
#ifdef CONFIG_DRIVER_NONE
&wpa_driver_none_ops,
#endif /* CONFIG_DRIVER_NONE */
NULL
};
1.4 driver_cmd_nl80211.c
看下wpa_driver_nl80211_ops的初始化，name就是传入的参数nl80211，文章一开始说的
driver_cmd = wpa_driver_nl80211_driver_cmd,
相当于启动的时候指定一个驱动，这边会有对应的结构体进行一些默认的初始化工作。
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,
.hapd_send_eapol = wpa_driver_nl80211_hapd_send_eapol,
.sta_set_flags = wpa_driver_nl80211_sta_set_flags,
.hapd_init = i802_init,
.hapd_deinit = i802_deinit,
.set_wds_sta = i802_set_wds_sta,
.get_seqnum = i802_get_seqnum,
.flush = i802_flush,
.get_inact_sec = i802_get_inact_sec,
.sta_clear_stats = i802_sta_clear_stats,
.set_rts = i802_set_rts,
.set_frag = i802_set_frag,
.set_tx_queue_params = i802_set_tx_queue_params,
.set_sta_vlan = driver_nl80211_set_sta_vlan,
.sta_deauth = i802_sta_deauth,
.sta_disassoc = i802_sta_disassoc,
.read_sta_data = driver_nl80211_read_sta_data,
.set_freq = i802_set_freq,
.send_action = driver_nl80211_send_action,
.send_action_cancel_wait = wpa_driver_nl80211_send_action_cancel_wait,
.remain_on_channel = wpa_driver_nl80211_remain_on_channel,
.cancel_remain_on_channel =
wpa_driver_nl80211_cancel_remain_on_channel,
.probe_req_report = driver_nl80211_probe_req_report,
.deinit_ap = wpa_driver_nl80211_deinit_ap,
.deinit_p2p_cli = wpa_driver_nl80211_deinit_p2p_cli,
.resume = wpa_driver_nl80211_resume,
.signal_monitor = nl80211_signal_monitor,
.signal_poll = nl80211_signal_poll,
.send_frame = nl80211_send_frame,
.set_param = nl80211_set_param,
.get_radio_name = nl80211_get_radio_name,
.add_pmkid = nl80211_add_pmkid,
.remove_pmkid = nl80211_remove_pmkid,
.flush_pmkid = nl80211_flush_pmkid,
.set_rekey_info = nl80211_set_rekey_info,
.poll_client = nl80211_poll_client,
.set_p2p_powersave = nl80211_set_p2p_powersave,
.start_dfs_cac = nl80211_start_radar_detection,
.stop_ap = wpa_driver_nl80211_stop_ap,
#ifdef CONFIG_TDLS
.send_tdls_mgmt = nl80211_send_tdls_mgmt,
.tdls_oper = nl80211_tdls_oper,
.tdls_enable_channel_switch = nl80211_tdls_enable_channel_switch,
.tdls_disable_channel_switch = nl80211_tdls_disable_channel_switch,
#endif /* CONFIG_TDLS */
.update_ft_ies = wpa_driver_nl80211_update_ft_ies,
.get_mac_addr = wpa_driver_nl80211_get_macaddr,
.get_survey = wpa_driver_nl80211_get_survey,
.status = wpa_driver_nl80211_status,
.switch_channel = nl80211_switch_channel,
#ifdef ANDROID_P2P
.set_noa = wpa_driver_set_p2p_noa,
.get_noa = wpa_driver_get_p2p_noa,
.set_ap_wps_ie = wpa_driver_set_ap_wps_p2p_ie,
#endif /* ANDROID_P2P */
#ifdef ANDROID
#ifndef ANDROID_LIB_STUB
.driver_cmd = wpa_driver_nl80211_driver_cmd,
#endif /* !ANDROID_LIB_STUB */
#endif /* ANDROID */
.vendor_cmd = nl80211_vendor_cmd,
.set_qos_map = nl80211_set_qos_map,
.set_wowlan = nl80211_set_wowlan,
.set_mac_addr = nl80211_set_mac_addr,
#ifdef CONFIG_MESH
.init_mesh = wpa_driver_nl80211_init_mesh,
.join_mesh = wpa_driver_nl80211_join_mesh,
.leave_mesh = wpa_driver_nl80211_leave_mesh,
#endif /* CONFIG_MESH */
.br_add_ip_neigh = wpa_driver_br_add_ip_neigh,
.br_delete_ip_neigh = wpa_driver_br_delete_ip_neigh,
.br_port_set_attr = wpa_driver_br_port_set_attr,
.br_set_net_param = wpa_driver_br_set_net_param,
.add_tx_ts = nl80211_add_ts,
.del_tx_ts = nl80211_del_ts,
.get_ifindex = nl80211_get_ifindex,
#ifdef CONFIG_DRIVER_NL80211_QCA
.roaming = nl80211_roaming,
.do_acs = wpa_driver_do_acs,
.set_band = nl80211_set_band,
.get_pref_freq_list = nl80211_get_pref_freq_list,
.set_prob_oper_freq = nl80211_set_prob_oper_freq,
.p2p_lo_start = nl80211_p2p_lo_start,
.p2p_lo_stop = nl80211_p2p_lo_stop,
.set_default_scan_ies = nl80211_set_default_scan_ies,
.set_tdls_mode = nl80211_set_tdls_mode,
#ifdef CONFIG_MBO
.get_bss_transition_status = nl80211_get_bss_transition_status,
.ignore_assoc_disallow = nl80211_ignore_assoc_disallow,
#endif /* CONFIG_MBO */
.set_bssid_blacklist = nl80211_set_bssid_blacklist,
#endif /* CONFIG_DRIVER_NL80211_QCA */
.configure_data_frame_filters = nl80211_configure_data_frame_filters,
.get_ext_capab = nl80211_get_ext_capab,
.update_connect_params = nl80211_update_connection_params,
};
2.总结
总的来说driver对象的一些方法取决于supplicant启动时所指定的wifi 驱动，比如nl80211对应的结构体就是wpa_driver_nl80211_ops，详细请见drivers.c中的驱动数组。