hostapd的分析[通俗易懂]

int main(int argc, char *argv[])
{
    struct hapd_interfaces interfaces;
    int ret = 1;
    size_t i, j;
    int c, debug = 0, daemonize = 0;
    char *pid_file = NULL;
    const char *log_file = NULL;
    const char *entropy_file = NULL;
    char **bss_config = NULL, **tmp_bss;
    size_t num_bss_configs = 0;
#ifdef CONFIG_DEBUG_LINUX_TRACING
    int enable_trace_dbg = 0;
#endif /* CONFIG_DEBUG_LINUX_TRACING */
    int start_ifaces_in_sync = 0;
    char **if_names = NULL;
    size_t if_names_size = 0;

    if (os_program_init())
        return -1;

    os_memset(&interfaces, 0, sizeof(interfaces));
    interfaces.reload_config = hostapd_reload_config;
    interfaces.config_read_cb = hostapd_config_read;
    interfaces.for_each_interface = hostapd_for_each_interface;
    interfaces.ctrl_iface_init = hostapd_ctrl_iface_init;
    interfaces.ctrl_iface_deinit = hostapd_ctrl_iface_deinit;
    interfaces.driver_init = hostapd_driver_init;
    interfaces.global_iface_path = NULL;
    interfaces.global_iface_name = NULL;
    interfaces.global_ctrl_sock = -1;
    dl_list_init(&interfaces.global_ctrl_dst);

    for (;;) {
        c = getopt(argc, argv, "b:Bde:f:hi:KP:STtu:vg:G:");
        if (c < 0)
            break;
        switch (c) {
        case 'h':
            usage();
            break;
        case 'd':
            debug++;
            if (wpa_debug_level > 0)
                wpa_debug_level--;
            break;
        case 'B':
            daemonize++;
            break;
        case 'e':
            entropy_file = optarg;
            break;
        case 'f':
            log_file = optarg;
            break;
        case 'K':
            wpa_debug_show_keys++;
            break;
        case 'P':
            os_free(pid_file);
            pid_file = os_rel2abs_path(optarg);
            break;
        case 't':
            wpa_debug_timestamp++;
            break;
#ifdef CONFIG_DEBUG_LINUX_TRACING
        case 'T':
            enable_trace_dbg = 1;
            break;
#endif /* CONFIG_DEBUG_LINUX_TRACING */
        case 'v':
            show_version();
            exit(1);
            break;
        case 'g':
            if (hostapd_get_global_ctrl_iface(&interfaces, optarg))
                return -1;
            break;
        case 'G':
            if (hostapd_get_ctrl_iface_group(&interfaces, optarg))
                return -1;
            break;
        case 'b':
            tmp_bss = os_realloc_array(bss_config,
                           num_bss_configs + 1,
                           sizeof(char *));
            if (tmp_bss == NULL)
                goto out;
            bss_config = tmp_bss;
            bss_config[num_bss_configs++] = optarg;
            break;
        case 'S':
            start_ifaces_in_sync = 1;
            break;
#ifdef CONFIG_WPS
        case 'u':
            return gen_uuid(optarg);
#endif /* CONFIG_WPS */
        case 'i':
            if (hostapd_get_interface_names(&if_names,
                            &if_names_size, optarg))
                goto out;
            break;
        default:
            usage();
            break;
        }
    }

    if (optind == argc && interfaces.global_iface_path == NULL &&
        num_bss_configs == 0)
        usage();

    wpa_msg_register_ifname_cb(hostapd_msg_ifname_cb);

    if (log_file)
        wpa_debug_open_file(log_file);
    else
        wpa_debug_setup_stdout();
#ifdef CONFIG_DEBUG_LINUX_TRACING
    if (enable_trace_dbg) {
        int tret = wpa_debug_open_linux_tracing();
        if (tret) {
            wpa_printf(MSG_ERROR, "Failed to enable trace logging");
            return -1;
        }
    }
#endif /* CONFIG_DEBUG_LINUX_TRACING */

    interfaces.count = argc - optind;
    if (interfaces.count || num_bss_configs) {
        interfaces.iface = os_calloc(interfaces.count + num_bss_configs,
                         sizeof(struct hostapd_iface *));
        if (interfaces.iface == NULL) {
            wpa_printf(MSG_ERROR, "malloc failed");
            return -1;
        }
    }

    if (hostapd_global_init(&interfaces, entropy_file)) {
        wpa_printf(MSG_ERROR, "Failed to initialize global context");
        return -1;
    }

    eloop_register_timeout(HOSTAPD_CLEANUP_INTERVAL, 0,
                   hostapd_periodic, &interfaces, NULL);

    if (fst_global_init()) {
        wpa_printf(MSG_ERROR,
               "Failed to initialize global FST context");
        goto out;
    }

#if defined(CONFIG_FST) && defined(CONFIG_CTRL_IFACE)
    if (!fst_global_add_ctrl(fst_ctrl_cli))
        wpa_printf(MSG_WARNING, "Failed to add CLI FST ctrl");
#endif /* CONFIG_FST && CONFIG_CTRL_IFACE */

    /* Allocate and parse configuration for full interface files */
    for (i = 0; i < interfaces.count; i++) {
        char *if_name = NULL;

        if (i < if_names_size)
            if_name = if_names[i];

        interfaces.iface[i] = hostapd_interface_init(&interfaces,
                                 if_name,
                                 argv[optind + i],
                                 debug);
        if (!interfaces.iface[i]) {
            wpa_printf(MSG_ERROR, "Failed to initialize interface");
            goto out;
        }
        if (start_ifaces_in_sync)
            interfaces.iface[i]->need_to_start_in_sync = 1;
    }

    /* Allocate and parse configuration for per-BSS files */
    for (i = 0; i < num_bss_configs; i++) {
        struct hostapd_iface *iface;
        char *fname;

        wpa_printf(MSG_INFO, "BSS config: %s", bss_config[i]);
        fname = os_strchr(bss_config[i], ':');
        if (fname == NULL) {
            wpa_printf(MSG_ERROR,
                   "Invalid BSS config identifier '%s'",
                   bss_config[i]);
            goto out;
        }
        *fname++ = '\0';
        iface = hostapd_interface_init_bss(&interfaces, bss_config[i],
                           fname, debug);
        if (iface == NULL)
            goto out;
        for (j = 0; j < interfaces.count; j++) {
            if (interfaces.iface[j] == iface)
                break;
        }
        if (j == interfaces.count) {
            struct hostapd_iface **tmp;
            tmp = os_realloc_array(interfaces.iface,
                           interfaces.count + 1,
                           sizeof(struct hostapd_iface *));
            if (tmp == NULL) {
                hostapd_interface_deinit_free(iface);
                goto out;
            }
            interfaces.iface = tmp;
            interfaces.iface[interfaces.count++] = iface;
        }
    }

    /* * Enable configured interfaces. Depending on channel configuration, * this may complete full initialization before returning or use a * callback mechanism to complete setup in case of operations like HT * co-ex scans, ACS, or DFS are needed to determine channel parameters. * In such case, the interface will be enabled from eloop context within * hostapd_global_run(). */
    interfaces.terminate_on_error = interfaces.count;
    for (i = 0; i < interfaces.count; i++) { 
        //根据配置文件设置iface信息
        if (hostapd_driver_init(interfaces.iface[i]) ||
            hostapd_setup_interface(interfaces.iface[i]))  //将配置文件通过写入驱动
            goto out;
    }

    hostapd_global_ctrl_iface_init(&interfaces);

    if (hostapd_global_run(&interfaces, daemonize, pid_file)) {
        wpa_printf(MSG_ERROR, "Failed to start eloop");
        goto out;
    }

    ret = 0;

 out:
    hostapd_global_ctrl_iface_deinit(&interfaces);
    /* Deinitialize all interfaces */
    for (i = 0; i < interfaces.count; i++) {
        if (!interfaces.iface[i])
            continue;
        interfaces.iface[i]->driver_ap_teardown =
            !!(interfaces.iface[i]->drv_flags &
               WPA_DRIVER_FLAGS_AP_TEARDOWN_SUPPORT);
        hostapd_interface_deinit_free(interfaces.iface[i]);
    }
    os_free(interfaces.iface);

    if (interfaces.eloop_initialized)
        eloop_cancel_timeout(hostapd_periodic, &interfaces, NULL);
    hostapd_global_deinit(pid_file, interfaces.eloop_initialized);
    os_free(pid_file);

    if (log_file)
        wpa_debug_close_file();
    wpa_debug_close_linux_tracing();

    os_free(bss_config);

    for (i = 0; i < if_names_size; i++)
        os_free(if_names[i]);
    os_free(if_names);

    fst_global_deinit();

    os_program_deinit();

    return ret;
}

static int hostapd_global_init(struct hapd_interfaces *interfaces, const char *entropy_file) { int i; os_memset(&global, 0, sizeof(global)); //重置global变量 hostapd_logger_register_cb(hostapd_logger_cb); if (eap_server_register_methods()) { //注册eap server的加密方法 wpa_printf(MSG_ERROR, "Failed to register EAP methods"); return -1; } if (eloop_init()) { wpa_printf(MSG_ERROR, "Failed to initialize event loop"); return -1; } interfaces->eloop_initialized = 1; random_init(entropy_file); #ifndef CONFIG_NATIVE_WINDOWS eloop_register_signal(SIGHUP, handle_reload, interfaces); eloop_register_signal(SIGUSR1, handle_dump_state, interfaces); #endif /* CONFIG_NATIVE_WINDOWS */ eloop_register_signal_terminate(handle_term, interfaces); #ifndef CONFIG_NATIVE_WINDOWS openlog("hostapd", 0, LOG_DAEMON); #endif /* CONFIG_NATIVE_WINDOWS */ for (i = 0; wpa_drivers[i]; i++) global.drv_count++; if (global.drv_count == 0) { wpa_printf(MSG_ERROR, "No drivers enabled"); return -1; } global.drv_priv = os_calloc(global.drv_count, sizeof(void *)); if (global.drv_priv == NULL) return -1; return 0; }

void random_init(const char *entropy_file) { os_free(random_entropy_file); if (entropy_file) random_entropy_file = os_strdup(entropy_file); else random_entropy_file = NULL; random_read_entropy(); #ifdef __linux__ if (random_fd >= 0) return; random_fd = open("/dev/random", O_RDONLY | O_NONBLOCK); if (random_fd < 0) { wpa_printf(MSG_ERROR, "random: Cannot open /dev/random: %s", strerror(errno)); return; } wpa_printf(MSG_DEBUG, "random: Trying to read entropy from " "/dev/random"); eloop_register_read_sock(random_fd, random_read_fd, NULL, NULL); #endif /* __linux__ */ random_write_entropy(); }

int eloop_register_sock(int sock, eloop_event_type type,
            eloop_sock_handler handler,
            void *eloop_data, void *user_data)
{
    struct eloop_sock_table *table;

    assert(sock >= 0);
    table = eloop_get_sock_table(type);
    return eloop_sock_table_add_sock(table, sock, handler,
                     eloop_data, user_data);
}

/** * hostapd_interface_init - Read configuration file and init BSS data * * This function is used to parse configuration file for a full interface (one * or more BSSes sharing the same radio) and allocate memory for the BSS * interfaces. No actiual driver operations are started. */ static struct hostapd_iface * hostapd_interface_init(struct hapd_interfaces *interfaces, const char *if_name, const char *config_fname, int debug) { struct hostapd_iface *iface; int k; wpa_printf(MSG_ERROR, "Configuration file: %s", config_fname); iface = hostapd_init(interfaces, config_fname); if (!iface) return NULL; if (if_name) { os_strlcpy(iface->conf->bss[0]->iface, if_name, sizeof(iface->conf->bss[0]->iface)); } iface->interfaces = interfaces; for (k = 0; k < debug; k++) { if (iface->bss[0]->conf->logger_stdout_level > 0) iface->bss[0]->conf->logger_stdout_level--; } if (iface->conf->bss[0]->iface[0] == '\0' && !hostapd_drv_none(iface->bss[0])) { wpa_printf(MSG_ERROR, "Interface name not specified in %s, nor by '-i' parameter", config_fname); hostapd_interface_deinit_free(iface); return NULL; } return iface; }

/** * hostapd_init - Allocate and initialize per-interface data * @config_file: Path to the configuration file * Returns: Pointer to the allocated interface data or %NULL on failure * * This function is used to allocate main data structures for per-interface * data. The allocated data buffer will be freed by calling * hostapd_cleanup_iface(). */ struct hostapd_iface * hostapd_init(struct hapd_interfaces *interfaces, const char *config_file) { struct hostapd_iface *hapd_iface = NULL; struct hostapd_config *conf = NULL; struct hostapd_data *hapd; size_t i; hapd_iface = hostapd_alloc_iface(); if (hapd_iface == NULL) goto fail; hapd_iface->config_fname = os_strdup(config_file); if (hapd_iface->config_fname == NULL) goto fail; conf = interfaces->config_read_cb(hapd_iface->config_fname);//读取配置文件 if (conf == NULL) goto fail; hapd_iface->conf = conf; hapd_iface->num_bss = conf->num_bss; hapd_iface->bss = os_calloc(conf->num_bss, sizeof(struct hostapd_data *)); if (hapd_iface->bss == NULL) goto fail; //根据配置文件中bss的配置个数conf->num_bss的值通过调用hostapd_alloc_bss_data分配空间及相关设置 for (i = 0; i < conf->num_bss; i++) { hapd = hapd_iface->bss[i] = hostapd_alloc_bss_data(hapd_iface, conf, conf->bss[i]); if (hapd == NULL) goto fail; hapd->msg_ctx = hapd; } return hapd_iface; fail: wpa_printf(MSG_ERROR, "Failed to set up interface with %s", config_file); if (conf) hostapd_config_free(conf); if (hapd_iface) { os_free(hapd_iface->config_fname); os_free(hapd_iface->bss); wpa_printf(MSG_DEBUG, "%s: free iface %p", __func__, hapd_iface); os_free(hapd_iface); } return NULL; } 

hostapd_setup_interface
------>setup_interface
    ------>hostapd_set_country
    ------>setup_interface2
        ------>hostapd_setup_interface_complete
                ------>hostapd_set_freq
                ------>hostapd_set_rts
    ------>hostapd_set_state
    ------>hostapd_tx_queue_para,   

static int hostapd_global_run(struct hapd_interfaces *ifaces, int daemonize, const char *pid_file) { #ifdef EAP_SERVER_TNC int tnc = 0; size_t i, k; for (i = 0; !tnc && i < ifaces->count; i++) { for (k = 0; k < ifaces->iface[i]->num_bss; k++) { if (ifaces->iface[i]->bss[0]->conf->tnc) { tnc++; break; } } } if (tnc && tncs_global_init() < 0) { 
   //调用tncs_global_init完成tnc相关的初始化 wpa_printf(MSG_ERROR, "Failed to initialize TNCS"); return -1; } #endif /* EAP_SERVER_TNC */ if (daemonize) { if (os_daemonize(pid_file)) { 
   //调用os_daemonize函数实现将该程序以后台进程运行 wpa_printf(MSG_ERROR, "daemon: %s", strerror(errno)); return -1; } if (eloop_sock_requeue()) { wpa_printf(MSG_ERROR, "eloop_sock_requeue: %s", strerror(errno)); return -1; } } eloop_run(); return 0; }

void eloop_run(void) { #ifdef CONFIG_ELOOP_POLL int num_poll_fds; int timeout_ms = 0; #endif /* CONFIG_ELOOP_POLL */ #ifdef CONFIG_ELOOP_SELECT fd_set *rfds, *wfds, *efds; struct timeval _tv; #endif /* CONFIG_ELOOP_SELECT */ #ifdef CONFIG_ELOOP_EPOLL int timeout_ms = -1; #endif /* CONFIG_ELOOP_EPOLL */ #ifdef CONFIG_ELOOP_KQUEUE struct timespec ts; #endif /* CONFIG_ELOOP_KQUEUE */ int res; struct os_reltime tv, now; #ifdef CONFIG_ELOOP_SELECT  //为三个文件描述符集申请空间 rfds = os_malloc(sizeof(*rfds)); wfds = os_malloc(sizeof(*wfds)); efds = os_malloc(sizeof(*efds)); if (rfds == NULL || wfds == NULL || efds == NULL) goto out; #endif /* CONFIG_ELOOP_SELECT */ while (!eloop.terminate && (!dl_list_empty(&eloop.timeout) || eloop.readers.count > 0 || eloop.writers.count > 0 || eloop.exceptions.count > 0)) { struct eloop_timeout *timeout; if (eloop.pending_terminate) { /* * This may happen in some corner cases where a signal * is received during a blocking operation. We need to * process the pending signals and exit if requested to * avoid hitting the SIGALRM limit if the blocking * operation took more than two seconds. */ // eloop_process_pending_signals函数对发生的信号进行处理 eloop_process_pending_signals(); if (eloop.terminate) break; } timeout = dl_list_first(&eloop.timeout, struct eloop_timeout, list); if (timeout) { //对超时时间进行设置timeout，主要是为下面调用的select函数会用到超时时间做准备 os_get_reltime(&now); if (os_reltime_before(&now, &timeout->time)) os_reltime_sub(&timeout->time, &now, &tv); else tv.sec = tv.usec = 0; #if defined(CONFIG_ELOOP_POLL) || defined(CONFIG_ELOOP_EPOLL) timeout_ms = tv.sec * 1000 + tv.usec / 1000; #endif /* defined(CONFIG_ELOOP_POLL) || defined(CONFIG_ELOOP_EPOLL) */ #ifdef CONFIG_ELOOP_SELECT _tv.tv_sec = tv.sec; _tv.tv_usec = tv.usec; #endif /* CONFIG_ELOOP_SELECT */ #ifdef CONFIG_ELOOP_KQUEUE ts.tv_sec = tv.sec; ts.tv_nsec = tv.usec * 1000L; #endif /* CONFIG_ELOOP_KQUEUE */ } #ifdef CONFIG_ELOOP_POLL num_poll_fds = eloop_sock_table_set_fds( &eloop.readers, &eloop.writers, &eloop.exceptions, eloop.pollfds, eloop.pollfds_map, eloop.max_pollfd_map); res = poll(eloop.pollfds, num_poll_fds, timeout ? timeout_ms : -1); #endif /* CONFIG_ELOOP_POLL */ #ifdef CONFIG_ELOOP_SELECT  //将申请的文件描述符集与eloop对象相结合，并调用select函数对这些文件发生异常进行监听 eloop_sock_table_set_fds(&eloop.readers, rfds); eloop_sock_table_set_fds(&eloop.writers, wfds); eloop_sock_table_set_fds(&eloop.exceptions, efds); res = select(eloop.max_sock + 1, rfds, wfds, efds, timeout ? &_tv : NULL); #endif /* CONFIG_ELOOP_SELECT */ #ifdef CONFIG_ELOOP_EPOLL if (eloop.count == 0) { res = 0; } else { res = epoll_wait(eloop.epollfd, eloop.epoll_events, eloop.count, timeout_ms); } #endif /* CONFIG_ELOOP_EPOLL */ #ifdef CONFIG_ELOOP_KQUEUE if (eloop.count == 0) { res = 0; } else { res = kevent(eloop.kqueuefd, NULL, 0, eloop.kqueue_events, eloop.kqueue_nevents, timeout ? &ts : NULL); } #endif /* CONFIG_ELOOP_KQUEUE */ if (res < 0 && errno != EINTR && errno != 0) { wpa_printf(MSG_ERROR, "eloop: %s: %s", #ifdef CONFIG_ELOOP_POLL "poll" #endif /* CONFIG_ELOOP_POLL */ #ifdef CONFIG_ELOOP_SELECT "select" #endif /* CONFIG_ELOOP_SELECT */ #ifdef CONFIG_ELOOP_EPOLL "epoll" #endif /* CONFIG_ELOOP_EPOLL */ #ifdef CONFIG_ELOOP_KQUEUE "kqueue" #endif /* CONFIG_ELOOP_EKQUEUE */ , strerror(errno)); goto out; } eloop.readers.changed = 0; eloop.writers.changed = 0; eloop.exceptions.changed = 0; eloop_process_pending_signals(); /* check if some registered timeouts have occurred */ timeout = dl_list_first(&eloop.timeout, struct eloop_timeout, list); if (timeout) { os_get_reltime(&now); if (!os_reltime_before(&now, &timeout->time)) { void *eloop_data = timeout->eloop_data; void *user_data = timeout->user_data; eloop_timeout_handler handler = timeout->handler; eloop_remove_timeout(timeout); handler(eloop_data, user_data); } } if (res <= 0) continue; if (eloop.readers.changed || eloop.writers.changed || eloop.exceptions.changed) { /* * Sockets may have been closed and reopened with the * same FD in the signal or timeout handlers, so we * must skip the previous results and check again * whether any of the currently registered sockets have * events. */ continue; } #ifdef CONFIG_ELOOP_POLL eloop_sock_table_dispatch(&eloop.readers, &eloop.writers, &eloop.exceptions, eloop.pollfds_map, eloop.max_pollfd_map); #endif /* CONFIG_ELOOP_POLL */ #ifdef CONFIG_ELOOP_SELECT eloop_sock_table_dispatch(&eloop.readers, rfds); eloop_sock_table_dispatch(&eloop.writers, wfds); eloop_sock_table_dispatch(&eloop.exceptions, efds); #endif /* CONFIG_ELOOP_SELECT */ #ifdef CONFIG_ELOOP_EPOLL eloop_sock_table_dispatch(eloop.epoll_events, res); #endif /* CONFIG_ELOOP_EPOLL */ #ifdef CONFIG_ELOOP_KQUEUE eloop_sock_table_dispatch(eloop.kqueue_events, res); #endif /* CONFIG_ELOOP_KQUEUE */ } eloop.terminate = 0; out: #ifdef CONFIG_ELOOP_SELECT os_free(rfds); os_free(wfds); os_free(efds); #endif /* CONFIG_ELOOP_SELECT */ return; }

static void eloop_process_pending_signals(void)
{
    int i;

    if (eloop.signaled == 0)//有没有信号产生，如果有，那么这个标志位将为1，说明有信号需要处理，如果为0，那么没有信号要处理，函数返回 
        return;
    eloop.signaled = 0;//将信号标示为置0，以便下次有信号产生时，置1 

    if (eloop.pending_terminate) { 
    //如果不用处理后面将会产生的信号，则立即向进程发送一个SIGALARM信号，然后将这个标志置0 
#ifndef CONFIG_NATIVE_WINDOWS
        alarm(0);
#endif /* CONFIG_NATIVE_WINDOWS */
        eloop.pending_terminate = 0;
    }

    for (i = 0; i < eloop.signal_count; i++) { //对信号标示进行处理 
        if (eloop.signals[i].signaled) {
            eloop.signals[i].signaled = 0; 
            //调用处理函数对相应的信号进行处理
            eloop.signals[i].handler(eloop.signals[i].sig,
                         eloop.signals[i].user_data);
        }
    }
}

    eloop_sock_table_set_fds(&eloop.readers, rfds);
    eloop_sock_table_set_fds(&eloop.writers, wfds);
    eloop_sock_table_set_fds(&eloop.exceptions, efds);
    res = select(eloop.max_sock + 1, rfds, wfds, efds,
             timeout ? &_tv : NULL); 

    eloop_sock_table_dispatch(&eloop.readers, rfds);
    eloop_sock_table_dispatch(&eloop.writers, wfds);
    eloop_sock_table_dispatch(&eloop.exceptions, efds);