ZJUWLAN auto connect

翻译

本文另有英文版本。

success

浙三本终于有了 WPA2 和 802.1x，再也不需要打开网页登录了。

最近 ZJUWLAN 总是莫名掉线，而且三本的垃圾网还要专门打开浏览器登陆，登陆完成之后还弹出来一个登陆成功的小窗口，用 i3wm 的话小窗口还直接被平铺……对于我这种伪完美主义者&强迫症来说简直无可忍受，于是突发奇想，能不能直接用脚本登陆上去，于是打开了 Chrome 的开发者工具，仔细研究了一番。

登陆页面就是一个 form，点击提交的时候，会调用 js/srun_portal.js 里面的 check1(frm)，代码如下，居然还贴心地给出了注释：

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function check1(frm) //弹窗认证
{
    if (frm.username.value == "") {
        alert("用户名不能为空，请输入用户名");
        frm.username.focus();
        return false;
    }

    if (frm.password.value == "") {
        alert("密码不能为空，请输入密码");
        frm.password.focus();
        return false;
    }

    var res1 = "";

    var e = Encrypt(frm.password.value);
    var save_me = (frm.save_me.checked) ? 1 : 0;
    var d = "action=login&username=" + $("input[name='username']").val() +
        "&password=" + frm.password.value +
        "&ac_id=" + $("input[name='ac_id']").val() +
        "&user_ip=" + $("input[name='user_ip']").val() +
        "&nas_ip=" + $("input[name='nas_ip']").val() +
        "&user_mac=" + $("input[name='user_mac']").val() +
        "&save_me=" + save_me +
        "&ajax=1";
    //这里要用AJAX同步提交POST
    $.ajax({
        type: "post",
        url: "/include/auth_action.php",
        action: 'login',
        data: d,
        async: false,
        success: function (res) {
            res1 = res;
        }
    });

    var p = /^login_ok,/;
    if (p.test(res1))//认证成功，弹出小窗口
    {
        var arr = res1.split(",");
        if (arr[1] != "")//写入用于双栈认证的COOKIE
        {
            setCookie("double_stack_login", arr[1]);
        }
        if (arr[2] != "")//写入用户名密码COOKIE
        {
            setCookie("login", arr[2]);
        }
        window.open("user_logout.html", "", "width=400,height=300,left=0,top=0,resizable=1");//弹出小窗口
        setTimeout("redirect()", 2000); //重定向到输入的网址
        //alert('登录成功');
        //window.location.href="http://202.117.1.166:8080/xjtu/index.do?method=mXJTU";
    }
    else {
        alert(res1); //提示错误信息
    }

    return false;
}

JS 基本没有什么内容，只需要把表单的内容 POST 到 /include/auth_action.php 这个路径就行了，如果返回的信息是 login_ok, 开头的话，就说明登陆成功了，直接 Python 解决之：

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#!/usr/bin/env python3
import requests
from bs4 import BeautifulSoup
import sys

ZJU_WLAN = 'https://net.zju.edu.cn'
ZJU_INDEX = '/'
ZJU_AUTH = '/include/auth_action.php'

HTTP = {
    'Host': 'net.zju.edu.cn',
    'Connection': 'keep-alive',
    'Accept-Encoding': 'gzip, deflate, br',
    'Accept-Language': 'zh-CN,zh;q=0.9',
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134'
}

XHR = {
    'Host': 'net.zju.edu.cn',
    'Connection': 'keep-alive',
    'Origin': 'https://net.zju.edu.cn',
    'X-Requested-With': 'XMLHttpRequest',
    'Content-Type': 'application/x-www-form-urlencoded',
    'Referer': 'https://net.zju.edu.cn/srun_portal_pc.php?&ac_id=3',
    'Accept-Encoding': 'gzip, deflate, br',
    'Accept-Language': 'zh-CN,zh;q=0.9',
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134'
}

def main():
    if len(sys.argv) != 3:
        print('usage: %s <username> <password>')
        exit()
    username = sys.argv[1]
    password = sys.argv[2]
    zju_session = requests.session()
    index = zju_session.get(ZJU_WLAN+ZJU_INDEX, headers=HTTP)
    soup = BeautifulSoup(index.content, "html.parser")
    ac_id = soup.find('input', {'name': 'ac_id'})['value']
    user_ip = soup.find('input', {'name': 'user_ip'})['value']
    nas_ip = soup.find('input', {'name': 'nas_ip'})['value']
    user_mac = soup.find('input', {'name': 'user_mac'})['value']
    data = {
        'action': 'login',
        'username': username,
        'password': password,
        'ac_id': ac_id,
        'user_ip': user_ip,
        'nas_ip': nas_ip,
        'user_mac': user_mac,
        'save_me': 0,
        'ajax': 1
    }
    auth = zju_session.post(ZJU_WLAN+ZJU_AUTH, data=data, headers=XHR)
    result = auth.content.decode('utf8')
    if result[:9] == 'login_ok,':
        print('[+] Login succeed!')
    else:
        print('[-] Failed '+result)

if __name__ == '__main__':
    main()

后来试了试，发现最初访问 https://net.zju.edu.cn/srun_portal_pc.php?&ac_id=3 这一步并没有什么用处，连个 cookie 都没给设，真不愧是三本的垃圾网……不过好歹还给跳转到了 HTTPS，说明网络中心基本的安全意识还是有的 hhh。

所以实际上只需要直接把 JS 里生成的那串数据 POST 过去就行了，正好最近在学习网络编程，于是改用 C 实现了一个登陆程序，输入用户名和密码作为参数就能登陆。写的比较烂，如有不妥之处还请多多指教（output 函数参考了 Nginx 中对于 ngx_log_stderr 函数的可变长度参数的实现，装个逼加个许可证 hhh）：

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/*
 * Copyright (c) 2018, Nagi
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <openssl/ssl.h>

const char net_zju_host[] = "net.zju.edu.cn";
const char net_zju_auth_path[] = "/include/auth_action.php";
const char net_zju_ok[] = "login_ok,";
const char *user_agent = "Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134";

#define SUCCESS 0
#define INFO 1
#define ERROR 2

void output(int type, const char *fmt, ...)
{
    va_list args;
    switch (type) {
    case SUCCESS: printf("\e[32m[+] "); break;
    case ERROR: printf("\e[31m[-] "); break;
    default: printf("\e[33m[!] "); break;
    }
    va_start(args, fmt);
    vprintf(fmt, args);
    va_end(args);
    puts("\e[0m");
    if (type == ERROR) exit(1);
}

void init_ssl()
{
    SSL_load_error_strings();
    SSL_library_init();
}

SSL_CTX *create_ctx()
{
    SSL_CTX *ctx;
    int result;
    ctx = SSL_CTX_new(TLS_method());
    if (ctx == NULL) output(ERROR, "SSL_CTX_new() failed");
    result = SSL_CTX_set_min_proto_version(ctx, TLS1_VERSION);
    if (result == 0) {
        SSL_CTX_free(ctx);
        output(ERROR, "SSL_CTX_set_min_proto_version() failed");
    }
    return ctx;
}

SSL *connect_ssl(SSL_CTX *ctx, int fd)
{
    SSL *ssl;
    int result;
    ssl = SSL_new(ctx);
    if (ssl == NULL) output(ERROR, "SSL_new() failed");
    result = SSL_set_fd(ssl, fd);
    if (result != 1) output(ERROR, "SSL_set_fd() failed");
    result = SSL_connect(ssl);
    if (result != 1) output(ERROR, "SSL handshake failed");
    return ssl;
}

static const char urlencode_chars[] = {
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1};

int urlencode(const char *in, char *out)
{
    int i, printed = 0;
    unsigned char n1, n2;
    for (i = 0; in[i] != '\0'; i++) {
        if (urlencode_chars[(unsigned)in[i]] != 0) {
            n1 = ((unsigned char)in[i]) >> 4;
            n2 = ((unsigned char)in[i]) & 0xF;
            out[printed++] = '%';
            out[printed++] = n1 > 9 ? '7' + n1 : '0' + n1;
            out[printed++] = n2 > 9 ? '7' + n2 : '0' + n2;
        } else out[printed++] = in[i];
    }
    out[printed] = '\0';
    return printed;
}

int generate_post(char *buf, char *username, char *password)
{
    int printed = 0, content_len;
    char data_buf[256];
    printed += sprintf(buf + printed, "POST %s HTTP/1.1\r\nHost: %s\r\nConnection: close\r\nOrigin: https://%s\r\n", net_zju_auth_path, net_zju_host, net_zju_host);
    printed += sprintf(buf + printed, "X-Requested-With: XMLHttpRequest\r\nContent-Type: application/x-www-form-urlencoded\r\nReferer: https://%s/srun_portal_pc.php?&ac_id=3\r\n", net_zju_host);
    printed += sprintf(buf + printed, "Accept-Encoding: gzip, deflate, br\r\nAccept-Language: zh-CN,zh;q=0.9\r\nUser-Agent: %s\r\n", user_agent);
    memset(data_buf, 0, sizeof(data_buf));
    content_len = 0;
    content_len += sprintf(data_buf + content_len, "action=login&username=");
    content_len += urlencode(username, data_buf + content_len);
    content_len += sprintf(data_buf + content_len, "&password=");
    content_len += urlencode(password, data_buf + content_len);
    content_len += sprintf(data_buf + content_len, "&ac_id=3&user_ip=&nas_ip=&user_mac=&save_me=0&ajax=1");
    printed += sprintf(buf + printed, "Content-Length: %d\r\n\r\n%s", content_len, data_buf);
    return printed;
}

void send_post(SSL *ssl, char *buf, size_t size)
{
    size_t send = 0, this_send;
    int result;
    output(INFO, "Sending the POST request to server");
#ifdef DEBUG
    puts(buf);
#endif
    while (send < size) {
        result = SSL_write_ex(ssl, buf + send, size - send, &this_send);
        if (result != 1) output(ERROR, "SSL_write_ex() failed");
        send += this_send;
        output(INFO, "Sent %ld/%ld bytes", send, size);
    }
}

void recv_result(SSL *ssl, char *buf, size_t size)
{
    size_t recv = 0, this_recv;
    int result;
    output(INFO, "Receiving the reply");
    while (1) {
        result = SSL_read_ex(ssl, buf + recv, size - recv, &this_recv);
        if (result != 1) break;
        recv += this_recv;
        output(INFO, "%ld bytes receivied", recv);
    }
    buf[recv] = '\0';
#ifdef DEBUG
    puts(buf);
#endif
}

void final_ssl(SSL *ssl, SSL_CTX *ctx)
{
    SSL_shutdown(ssl);
    SSL_free(ssl);
    SSL_CTX_free(ctx);
}

int main(int argc, char *argv[], char *envp[])
{
    int auth_sock, result, post_size;
    struct sockaddr_in net_zju_addr;
    char post_buf[1024], recv_buf[1024], net_zju_ip[16];
    char *username, *password, *pos;
    struct hostent *resolve_result;
    SSL_CTX *ctx;
    SSL *ssl;

    if (argc != 3) {
        output(INFO, "Usage: %s <username> <password>", argv[0]);
        exit(1);
    }
    username = argv[1];
    password = argv[2];
    memset(post_buf, 0, sizeof(post_buf));
    init_ssl();
    ctx = create_ctx();
    resolve_result = gethostbyname(net_zju_host);
    if (resolve_result == NULL) output(ERROR, "gethostbyname() failed");
    if (resolve_result->h_addrtype != AF_INET) output(ERROR, "Can't get IPv4 address");
    net_zju_addr.sin_family = AF_INET;
    net_zju_addr.sin_port = htons(443);
    memcpy(&(net_zju_addr.sin_addr), resolve_result->h_addr_list[0], 4);
    inet_ntop(AF_INET, &(net_zju_addr.sin_addr), net_zju_ip, sizeof(net_zju_ip));
    output(INFO, "Using the IP address %s", net_zju_ip);
    auth_sock = socket(AF_INET, SOCK_STREAM, 0);
    if (auth_sock < 0) output(ERROR, "socket() failed");
    result = connect(auth_sock, (struct sockaddr *)&net_zju_addr, sizeof(struct sockaddr));
    if (result != 0) output(ERROR, "connect() failed");
    output(INFO, "Connected to net.zju.edu.cn");
    ssl = connect_ssl(ctx, auth_sock);
    post_size = generate_post(post_buf, username, password);
    send_post(ssl, post_buf, (size_t)post_size);
    recv_result(ssl, recv_buf, sizeof(recv_buf));
    pos = strstr(recv_buf, net_zju_ok);
    if (pos != NULL) output(SUCCESS, "Auth succeed");
    else {
        pos = strstr(recv_buf, "\r\n\r\n");
        if (pos != NULL) output(ERROR, "Auth failed, %s", pos + 4);
        else output(ERROR, "Auth failed");
    }
    final_ssl(ssl, ctx);
    return 0;
}

1
$ gcc -O2 -Wall zjuwlan.c -o zjuwlan -lcrypto -lssl