本文為《深入理解Android Wi-Fi、NFC和GPS卷》讀書筆記，Android源碼為Android 5.1

wpa_supplicant 是一個(gè)開(kāi)源軟件項(xiàng)目，它實(shí)現(xiàn)了 Station 對(duì)無(wú)線網(wǎng)絡(luò)進(jìn)行管理和控制的功能。
main函數(shù)分析

android-5.1/external/wpa_supplicant_8/wpa_supplicant/main.c

int main(int argc, char *argv[])
{int c, i;struct wpa_interface *ifaces, *iface;int iface_count, exitcode = -1;struct wpa_params params;struct wpa_global *global;//Android 平臺(tái)中， 下面這個(gè)函數(shù)的實(shí)現(xiàn)在 os_unix.c 中。 Android 對(duì)其做了一些修改，主要是權(quán)限方面的設(shè)置防止某些情況下被破解者利用權(quán)限漏洞以獲取 root 權(quán)限if (os_program_init())return -1;os_memset(?ms, 0, sizeof(params));params.wpa_debug_level = MSG_INFO;iface = ifaces = os_zalloc(sizeof(struct wpa_interface));if (ifaces == NULL)return -1;iface_count = 1;wpa_supplicant_fd_workaround(1);	//輸入輸出重定向到 /dev/null 設(shè)備for (;;) {	//參數(shù)解析c = getopt(argc, argv,"b:Bc:C:D:de:f:g:G:hi:I:KLm:No:O:p:P:qsTtuvW");if (c < 0)break;switch (c) {case 'b':iface->bridge_ifname = optarg;break;case 'B':params.daemonize++;break;case 'c'://指定配置文件名。注意，該參數(shù)賦值給了 wpa_interface 中的變量iface->confname = optarg;break;case 'C':iface->ctrl_interface = optarg;break;case 'D'://指定 driver 名稱iface->driver = optarg;break;case 'd':
#ifdef CONFIG_NO_STDOUT_DEBUGprintf("Debugging disabled with ""CONFIG_NO_STDOUT_DEBUG=y build time ""option.\n");goto out;
#else /* CONFIG_NO_STDOUT_DEBUG */params.wpa_debug_level--;break;
#endif /* CONFIG_NO_STDOUT_DEBUG */case 'e'://指定初始隨機(jī)數(shù)文件，用于后續(xù)隨機(jī)數(shù)的生成params.entropy_file = optarg;break;
#ifdef CONFIG_DEBUG_FILEcase 'f':params.wpa_debug_file_path = optarg;break;
#endif /* CONFIG_DEBUG_FILE */case 'g':params.ctrl_interface = optarg;break;case 'G':params.ctrl_interface_group = optarg;break;case 'h':usage();exitcode = 0;goto out;case 'i'://指定網(wǎng)絡(luò)設(shè)備接口名iface->ifname = optarg;break;case 'I':iface->confanother = optarg;break;case 'K':params.wpa_debug_show_keys++;break;case 'L':license();exitcode = 0;goto out;
#ifdef CONFIG_P2Pcase 'm':iface->conf_p2p_dev = optarg;break;
#endif /* CONFIG_P2P */case 'o':params.override_driver = optarg;break;case 'O':params.override_ctrl_interface = optarg;break;case 'p':iface->driver_param = optarg;break;case 'P':os_free(params.pid_file);params.pid_file = os_rel2abs_path(optarg);break;case 'q':params.wpa_debug_level++;break;
#ifdef CONFIG_DEBUG_SYSLOGcase 's':params.wpa_debug_syslog++;break;
#endif /* CONFIG_DEBUG_SYSLOG */
#ifdef CONFIG_DEBUG_LINUX_TRACINGcase 'T':params.wpa_debug_tracing++;break;
#endif /* CONFIG_DEBUG_LINUX_TRACING */case 't':params.wpa_debug_timestamp++;break;
#ifdef CONFIG_DBUScase 'u':params.dbus_ctrl_interface = 1;break;
#endif /* CONFIG_DBUS */case 'v':printf("%s\n", wpa_supplicant_version);exitcode = 0;goto out;case 'W':params.wait_for_monitor++;break;case 'N':iface_count++;iface = os_realloc_array(ifaces, iface_count,sizeof(struct wpa_interface));if (iface == NULL)goto out;ifaces = iface;iface = &ifaces[iface_count - 1]; os_memset(iface, 0, sizeof(*iface));break;default:usage();exitcode = 0;goto out;}}exitcode = 0;//關(guān)鍵函數(shù)：根據(jù)傳入的參數(shù)，創(chuàng)建并初始化一個(gè) wpa_global 對(duì)象global = wpa_supplicant_init(?ms);if (global == NULL) {wpa_printf(MSG_ERROR, "Failed to initialize wpa_supplicant");exitcode = -1;goto out;} else {wpa_printf(MSG_INFO, "Successfully initialized ""wpa_supplicant");}for (i = 0; exitcode == 0 && i < iface_count; i++) {struct wpa_supplicant *wpa_s;if ((ifaces[i].confname == NULL &&ifaces[i].ctrl_interface == NULL) ||ifaces[i].ifname == NULL) {if (iface_count == 1 && (params.ctrl_interface ||params.dbus_ctrl_interface))break;usage();exitcode = -1;break;}//WPAS 支持操作多個(gè)無(wú)線網(wǎng)絡(luò)設(shè)備，此處需將它們一一添加到WPAS中//WPAS 內(nèi)部將初始化這些設(shè)備wpa_s = wpa_supplicant_add_iface(global, &ifaces[i]);if (wpa_s == NULL) {exitcode = -1;break;}
#ifdef CONFIG_P2Pif (wpa_s->global->p2p == NULL &&(wpa_s->drv_flags &WPA_DRIVER_FLAGS_DEDICATED_P2P_DEVICE) &&wpas_p2p_add_p2pdev_interface(wpa_s, iface->conf_p2p_dev) <0)exitcode = -1;
#endif /* CONFIG_P2P */}//Android 平臺(tái)中， wpa_supplicant 通過(guò) select 或 epoll 方式實(shí)現(xiàn)多路 I/O 復(fù)用。if (exitcode == 0)exitcode = wpa_supplicant_run(global);wpa_supplicant_deinit(global);out:wpa_supplicant_fd_workaround(0);os_free(ifaces);os_free(params.pid_file);os_program_deinit();return exitcode;
}

wpa_interface 用于描述一個(gè)無(wú)線網(wǎng)絡(luò)設(shè)備。
android-5.1/external/wpa_supplicant_8/wpa_supplicant/wpa_supplicant_i.h

struct wpa_interface {/*** confname - Configuration name (file or profile) name** This can also be %NULL when a configuration file is not used. In* that case, ctrl_interface must be set to allow the interface to be* configured.*/const char *confname;/*** ctrl_interface - Control interface parameter** If a configuration file is not used, this variable can be used to* set the ctrl_interface parameter that would have otherwise been read* from the configuration file. If both confname and ctrl_interface are* set, ctrl_interface is used to override the value from configuration* file.*/const char *ctrl_interface;/*** driver - Driver interface name, or %NULL to use the default driver*/const char *driver;/*** driver_param - Driver interface parameters** If a configuration file is not used, this variable can be used to* set the driver_param parameters that would have otherwise been read* from the configuration file. If both confname and driver_param are* set, driver_param is used to override the value from configuration* file.*/const char *driver_param;/*** ifname - Interface name*/const char *ifname;/*** bridge_ifname - Optional bridge interface name** If the driver interface (ifname) is included in a Linux bridge* device, the bridge interface may need to be used for receiving EAPOL* frames. This can be enabled by setting this variable to enable* receiving of EAPOL frames from an additional interface.*/const char *bridge_ifname;
};

wpa_global 是一個(gè)全局性質(zhì)的上下文信息。
android-5.1/external/wpa_supplicant_8/wpa_supplicant/wpa_supplicant_i.h

struct wpa_global {struct wpa_supplicant *ifaces;	//ifaces 變量指向一個(gè) wpa_supplicant 對(duì)象。//系統(tǒng)中所有的 wpa_supplicant 對(duì)象將通過(guò)單項(xiàng)鏈表連接在一起，所以 ifaces 變量指向一個(gè) wpa_supplicant 對(duì)象鏈表。 struct wpa_params params;struct ctrl_iface_global_priv *ctrl_iface;	//全局控制接口，如果設(shè)置該接口，其他 wpa_supplicant 設(shè)置的控制接口將被取代struct wpas_dbus_priv *dbus;void **drv_priv;			//drv_priv 包含 driver wrapper 所需要的全局上下文信息。size_t drv_count;			//代表當(dāng)前編譯到系統(tǒng)中的 driver wrapper 個(gè)數(shù)。struct os_time suspend_time;struct p2p_data *p2p;struct wpa_supplicant *p2p_init_wpa_s;struct wpa_supplicant *p2p_group_formation;u8 p2p_dev_addr[ETH_ALEN];struct dl_list p2p_srv_bonjour; /* struct p2p_srv_bonjour */struct dl_list p2p_srv_upnp; /* struct p2p_srv_upnp */int p2p_disabled;int cross_connection;struct wpa_freq_range *p2p_disallow_freq;unsigned int num_p2p_disallow_freq;enum wpa_conc_pref {WPA_CONC_PREF_NOT_SET,WPA_CONC_PREF_STA,WPA_CONC_PREF_P2P} conc_pref;unsigned int p2p_cb_on_scan_complete:1;#ifdef CONFIG_WIFI_DISPLAYint wifi_display;
#define MAX_WFD_SUBELEMS 10struct wpabuf *wfd_subelem[MAX_WFD_SUBELEMS];
#endif /* CONFIG_WIFI_DISPLAY */
};

wpa_supplicant 是WPAS的核心數(shù)據(jù)結(jié)構(gòu)。 一個(gè) Interface 對(duì)應(yīng)有一個(gè) wpa_supplicant 對(duì)象。

struct wpa_supplicant {struct wpa_global *global;struct wpa_supplicant *parent;struct wpa_supplicant *next;	//系統(tǒng)中所有 wpa_supplicant 對(duì)象都通過(guò) next 變量鏈接在一起struct l2_packet_data *l2;struct l2_packet_data *l2_br;unsigned char own_addr[ETH_ALEN];char ifname[100];
#ifdef CONFIG_CTRL_IFACE_DBUSchar *dbus_path;
#endif /* CONFIG_CTRL_IFACE_DBUS */
#ifdef CONFIG_CTRL_IFACE_DBUS_NEWchar *dbus_new_path;char *dbus_groupobj_path;
#ifdef CONFIG_APchar *preq_notify_peer;
#endif /* CONFIG_AP */
#endif /* CONFIG_CTRL_IFACE_DBUS_NEW */char bridge_ifname[16];char *confname;struct wpa_config *conf;int countermeasures;os_time_t last_michael_mic_error;u8 bssid[ETH_ALEN];u8 pending_bssid[ETH_ALEN]; /* If wpa_state == WPA_ASSOCIATING, this* field contains the target BSSID. */int reassociate; /* reassociation requested */int disconnected; /* all connections disabled; i.e., do no reassociate* before this has been cleared */struct wpa_ssid *current_ssid;struct wpa_bss *current_bss;int ap_ies_from_associnfo;unsigned int assoc_freq;/* Selected configuration (based on Beacon/ProbeResp WPA IE) */int pairwise_cipher;int group_cipher;int key_mgmt;int wpa_proto;int mgmt_group_cipher;void *drv_priv; /* private data used by driver_ops */void *global_drv_priv;u8 *bssid_filter;size_t bssid_filter_count;/* previous scan was wildcard when interleaving between* wildcard scans and specific SSID scan when max_ssids=1 */int prev_scan_wildcard;struct wpa_ssid *prev_scan_ssid; /* previously scanned SSID;* NULL = not yet initialized (start* with wildcard SSID)* WILDCARD_SSID_SCAN = wildcard* SSID was used in the previous scan*/
#define WILDCARD_SSID_SCAN ((struct wpa_ssid *) 1)struct wpa_ssid *prev_sched_ssid; /* last SSID used in sched scan */int sched_scan_timeout;int sched_scan_interval;int first_sched_scan;int sched_scan_timed_out;void (*scan_res_handler)(struct wpa_supplicant *wpa_s,struct wpa_scan_results *scan_res);struct dl_list bss; /* struct wpa_bss::list */struct dl_list bss_id; /* struct wpa_bss::list_id */size_t num_bss;unsigned int bss_update_idx;unsigned int bss_next_id;/** Pointers to BSS entries in the order they were in the last scan* results.*/struct wpa_bss **last_scan_res;unsigned int last_scan_res_used;unsigned int last_scan_res_size;int last_scan_full;struct os_time last_scan;struct wpa_driver_ops *driver;int interface_removed; /* whether the network interface has been* removed */struct wpa_sm *wpa;struct eapol_sm *eapol;struct ctrl_iface_priv *ctrl_iface;enum wpa_states wpa_state;int scanning;int sched_scanning;int new_connection;int reassociated_connection;int eapol_received; /* number of EAPOL packets received after the* previous association event */struct scard_data *scard;
#ifdef PCSC_FUNCSchar imsi[20];int mnc_len;
#endif /* PCSC_FUNCS */unsigned char last_eapol_src[ETH_ALEN];int keys_cleared;struct wpa_blacklist *blacklist;int scan_req; /* manual scan request; this forces a scan even if there* are no enabled networks in the configuration */int scan_runs; /* number of scan runs since WPS was started */int *next_scan_freqs;int scan_interval; /* time in sec between scans to find suitable AP */int normal_scans; /* normal scans run before sched_scan */unsigned int drv_flags;unsigned int drv_enc;/** A bitmap of supported protocols for probe response offload. See* struct wpa_driver_capa in driver.h*/unsigned int probe_resp_offloads;int max_scan_ssids;int max_sched_scan_ssids;int sched_scan_supported;unsigned int max_match_sets;unsigned int max_remain_on_chan;unsigned int max_stations;int pending_mic_error_report;int pending_mic_error_pairwise;int mic_errors_seen; /* Michael MIC errors with the current PTK */struct wps_context *wps;int wps_success; /* WPS success event received */struct wps_er *wps_er;int blacklist_cleared;struct wpabuf *pending_eapol_rx;struct os_time pending_eapol_rx_time;u8 pending_eapol_rx_src[ETH_ALEN];struct ibss_rsn *ibss_rsn;int set_sta_uapsd;int sta_uapsd;int set_ap_uapsd;int ap_uapsd;#ifdef CONFIG_SMEstruct {u8 ssid[32];size_t ssid_len;int freq;u8 assoc_req_ie[200];size_t assoc_req_ie_len;int mfp;int ft_used;u8 mobility_domain[2];u8 *ft_ies;size_t ft_ies_len;u8 prev_bssid[ETH_ALEN];int prev_bssid_set;int auth_alg;int proto;int sa_query_count; /* number of pending SA Query requests;* 0 = no SA Query in progress */int sa_query_timed_out;u8 *sa_query_trans_id; /* buffer of WLAN_SA_QUERY_TR_ID_LEN ** sa_query_count octets of pending* SA Query transaction identifiers */struct os_time sa_query_start;u8 sched_obss_scan;u16 obss_scan_int;u16 bss_max_idle_period;} sme;
#endif /* CONFIG_SME */#ifdef CONFIG_APstruct hostapd_iface *ap_iface;void (*ap_configured_cb)(void *ctx, void *data);void *ap_configured_cb_ctx;void *ap_configured_cb_data;
#endif /* CONFIG_AP */unsigned int off_channel_freq;struct wpabuf *pending_action_tx;u8 pending_action_src[ETH_ALEN];u8 pending_action_dst[ETH_ALEN];u8 pending_action_bssid[ETH_ALEN];unsigned int pending_action_freq;int pending_action_no_cck;int pending_action_without_roc;void (*pending_action_tx_status_cb)(struct wpa_supplicant *wpa_s,unsigned int freq, const u8 *dst,const u8 *src, const u8 *bssid,const u8 *data, size_t data_len,enum offchannel_send_action_resultresult);unsigned int roc_waiting_drv_freq;int action_tx_wait_time;#ifdef CONFIG_P2Pstruct p2p_go_neg_results *go_params;int create_p2p_iface;u8 pending_interface_addr[ETH_ALEN];char pending_interface_name[100];int pending_interface_type;int p2p_group_idx;unsigned int pending_listen_freq;unsigned int pending_listen_duration;enum {NOT_P2P_GROUP_INTERFACE,P2P_GROUP_INTERFACE_PENDING,P2P_GROUP_INTERFACE_GO,P2P_GROUP_INTERFACE_CLIENT} p2p_group_interface;struct p2p_group *p2p_group;int p2p_long_listen; /* remaining time in long Listen state in ms */char p2p_pin[10];int p2p_wps_method;u8 p2p_auth_invite[ETH_ALEN];int p2p_sd_over_ctrl_iface;int p2p_in_provisioning;int pending_invite_ssid_id;int show_group_started;u8 go_dev_addr[ETH_ALEN];int pending_pd_before_join;u8 pending_join_iface_addr[ETH_ALEN];u8 pending_join_dev_addr[ETH_ALEN];int pending_join_wps_method;int p2p_join_scan_count;int auto_pd_scan_retry;int force_long_sd;u16 pending_pd_config_methods;enum {NORMAL_PD, AUTO_PD_GO_NEG, AUTO_PD_JOIN} pending_pd_use;/** Whether cross connection is disallowed by the AP to which this* interface is associated (only valid if there is an association).*/int cross_connect_disallowed;/** Whether this P2P group is configured to use cross connection (only* valid if this is P2P GO interface). The actual cross connect packet* forwarding may not be configured depending on the uplink status.*/int cross_connect_enabled;/* Whether cross connection forwarding is in use at the moment. */int cross_connect_in_use;/** Uplink interface name for cross connection*/char cross_connect_uplink[100];unsigned int sta_scan_pending:1;unsigned int p2p_auto_join:1;unsigned int p2p_auto_pd:1;unsigned int p2p_persistent_group:1;unsigned int p2p_fallback_to_go_neg:1;unsigned int p2p_pd_before_go_neg:1;unsigned int p2p_go_ht40:1;int p2p_persistent_go_freq;int p2p_persistent_id;int p2p_go_intent;int p2p_connect_freq;struct os_time p2p_auto_started;
#endif /* CONFIG_P2P */struct wpa_ssid *bgscan_ssid;const struct bgscan_ops *bgscan;void *bgscan_priv;const struct autoscan_ops *autoscan;struct wpa_driver_scan_params *autoscan_params;void *autoscan_priv;struct wpa_ssid *connect_without_scan;struct wps_ap_info *wps_ap;size_t num_wps_ap;int wps_ap_iter;int after_wps;int known_wps_freq;unsigned int wps_freq;int wps_fragment_size;int auto_reconnect_disabled;/* Channel preferences for AP/P2P GO use */int best_24_freq;int best_5_freq;int best_overall_freq;struct gas_query *gas;#ifdef CONFIG_INTERWORKINGunsigned int fetch_anqp_in_progress:1;unsigned int network_select:1;unsigned int auto_select:1;unsigned int auto_network_select:1;unsigned int fetch_all_anqp:1;
#endif /* CONFIG_INTERWORKING */unsigned int drv_capa_known;struct {struct hostapd_hw_modes *modes;u16 num_modes;u16 flags;} hw;int pno;/* WLAN_REASON_* reason codes. Negative if locally generated. */int disconnect_reason;struct ext_password_data *ext_pw;struct wpabuf *last_gas_resp;u8 last_gas_addr[ETH_ALEN];u8 last_gas_dialog_token;
};

struct ctrl_iface_global_priv {int sock; //用于通信的 socket 句柄u8 cookie[COOKIE_LEN];
};

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