【转】Hostapd工作流程分析 【转】Hostapd工作流程分析
转自：http://blog.chinaunix.net/uid-30081165-id-5290531.html
Hostapd是一个运行在用户态的守护进程，可以通过Hostapd来读取配置文件，通过nl802.11来控制底层的状态如RTS/CTS beacon帧间隔等等信息；也可以读取相关的信息。
其代码框架如下图所示：hostapd_cli是基于文本的命令命令界面，GUI则是图形控制界面；event loop是一个死循环函数用于接收和处理各种事件信息。
下图是各种命令配置工具以及无线工作流程：
实际上可以看到无论是wpa_supplient iw还是hostapd工具都是通过调用libnl的相关方法来完成信息的配置预读取的。
接下来分析hostaod的主函数：
int main(int argc, char *argv[]) { struct hapd_interfaces interfaces; int ret = 1; size_t i, j; int c, debug = 0; 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 */ 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; wpa_supplicant_event = hostapd_wpa_event; //分析配置文件信息 for (;;) { c = getopt(argc, argv, "b:Bde:f:hKP:Ttu:g:G:v::"); 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': if (optarg) exit(!has_feature(optarg)); 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; #ifdef CONFIG_WPS case 'u': return gen_uuid(optarg); #endif /* CONFIG_WPS */ 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); #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; } } //初始化global context信息 if (hostapd_global_init(&interfaces, entropy_file)) { wpa_printf(MSG_ERROR, "Failed to initilize global context"); return -1; } /* Allocate and parse configuration for full interface files */ for (i = 0; i < interfaces.count; i++) { interfaces.iface[i] = hostapd_interface_init(&interfaces, argv[optind + i], debug); if (!interfaces.iface[i]) { wpa_printf(MSG_ERROR, "Failed to initialize interface"); goto out; } } /* 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++ = '