wifidog 源码初分析（2）

来源：互联网发布：通达信期货 mac 编辑：程序博客网时间：2024/05/16 12:41

上一篇分析了接入设备的首次浏览器访问请求如何通过防火墙过滤规则重定向到 wifidog 的 HTTP 服务中，本篇主要分析了 wifidog 在接收到接入设备的 HTTP 访问请求后，如何将此 HTTP 请求重定向到认证服务器(auth-server) 上。

通过上面的防火墙规则，会将通过上面的防火墙规则，会将HTTP请求的外部IP地址和端口通过NAT方式重定向至本地wifidog内嵌HTTP服务器的地址和端口上，并由内嵌HTTP服务器进行服务，而内嵌HTTP服务器的路径和回调处理如下：

if ((webserver = httpdCreate(config->gw_address, config->gw_port)) == NULL) {    debug(LOG_ERR, "Could not create web server: %s", strerror(errno));    exit(1);}debug(LOG_DEBUG, "Assigning callbacks to web server");httpdAddCContent(webserver, "/", "wifidog", 0, NULL, http_callback_wifidog);httpdAddCContent(webserver, "/wifidog", "", 0, NULL, http_callback_wifidog);httpdAddCContent(webserver, "/wifidog", "about", 0, NULL, http_callback_about);httpdAddCContent(webserver, "/wifidog", "status", 0, NULL, http_callback_status);httpdAddCContent(webserver, "/wifidog", "auth", 0, NULL, http_callback_auth);                                               httpdAddC404Content(webserver, http_callback_404);

客户端首次访问时回调客户端首次访问时回调http_callback_404函数，在该函数中根据获取的客户端信息来配置重定向的URL fragment，如下：

voidhttp_callback_404(httpd *webserver, request *r){    char tmp_url[MAX_BUF],            *url,            *mac;    s_config    *config = config_get_config();    t_auth_serv *auth_server = get_auth_server();    memset(tmp_url, 0, sizeof(tmp_url));    /*     * XXX Note the code below assumes that the client's request is a plain     * http request to a standard port. At any rate, this handler is called only     * if the internet/auth server is down so it's not a huge loss, but still.     */ /* 用户需要访问的URL */        snprintf(tmp_url, (sizeof(tmp_url) - 1), "http://%s%s%s%s",                        r->request.host,                        r->request.path,                        r->request.query[0] ? "?" : "",                        r->request.query);    url = httpdUrlEncode(tmp_url);    if (!is_online()) {        /* 路由器都接入不到 internet */        char * buf;        send_http_page(r, "Uh oh! Internet access unavailable!", buf);        free(buf);    }    else if (!is_auth_online()) {        /* auth server 挂起 */        char * buf;        send_http_page(r, "Uh oh! Login screen unavailable!", buf);        free(buf);    }    else {        /* 配置重定向到 auth server 的 url 参数 */        char *urlFragment;        if (!(mac = arp_get(r->clientAddr))) {            /* We could not get their MAC address */            debug(LOG_INFO, "Failed to retrieve MAC address for ip %s, so not putting in the login request", r->clientAddr);            safe_asprintf(&urlFragment, "%sgw_address=%s&gw_port=%d&gw_id=%s&url=%s",                auth_server->authserv_login_script_path_fragment,                config->gw_address,                config->gw_port,                config->gw_id,                url);        } else {                      debug(LOG_INFO, "Got client MAC address for ip %s: %s", r->clientAddr, mac);            safe_asprintf(&urlFragment, "%sgw_address=%s&gw_port=%d&gw_id=%s&mac=%s&url=%s",                auth_server->authserv_login_script_path_fragment,                config->gw_address,                config->gw_port,                config->gw_id,                mac,                url);        }        /* 调用该函数将用户请求重定向到 auth server 的登录页面 */        http_send_redirect_to_auth(r, urlFragment, "Redirect to login page");        free(urlFragment);    }    free(url);}

上面代码基本不用解释，具体重定向至auth server的消息在下面的 http_send_redirect_to_auth 函数中实现：

void http_send_redirect_to_auth(request *r, char *urlFragment, char *text){    char *protocol = NULL;    int port = 80;    t_auth_serv *auth_server = get_auth_server();    if (auth_server->authserv_use_ssl) {        protocol = "https";        port = auth_server->authserv_ssl_port;    } else {        protocol = "http";        port = auth_server->authserv_http_port;    }                                                char *url = NULL;    safe_asprintf(&url, "%s://%s:%d%s%s",        protocol,        auth_server->authserv_hostname,        port,        auth_server->authserv_path,        urlFragment    );    http_send_redirect(r, url, text);    free(url);}

具体的重定向URL给个实例：

POST /login/?gw_address=192.168.1.1&gw_port=2060&gw_id=default&mac=44:94:fc:ef:28:40&url=http%3A//www.baidu.com/ HTTP/1.1

可以看到这里有这几个参数信息：

2gw_address，路由器的LAN地址

2gw_port：为wifidog的监听端口

2gw_id：路由器的标识名

2mac：客户端设备的MAC地址

2url：为客户端访问的原URL（以便于重定向）

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