diff --git a/CS3.1.3.py b/CS3.1.3.py
new file mode 100644
index 0000000..b7a8d4e
--- /dev/null
+++ b/CS3.1.3.py
@@ -0,0 +1,468 @@
+import threading
+import json
+from flask import Flask, jsonify, request, send_from_directory
+import sqlite3
+import socket
+import secrets
+import time
+import os
+import logging
+import re  # 添加正则表达式模块
+
+# 在文件顶部添加常量定义
+AVATAR_BASE_DIR = "avatar"  # 头像存储基础目录
+DEFAULT_AVATAR = "default_avatar.png"  # 默认头像文件名
+
+# 配置日志
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
+)
+logger = logging.getLogger(__name__)
+
+app = Flask(__name__)
+socket_server = socket.socket()
+socket_server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+# 修改数据结构：使用用户名作为主键
+active_connections = {}  # {username: {'conn': conn, 'ip': ip, 'last_active': timestamp}}
+chat_connections = []    # 所有活跃连接列表
+tokens = {}              # 令牌管理
+
+def get_db_connection():
+    conn = sqlite3.connect("usr.db")
+    conn.row_factory = sqlite3.Row
+    return conn
+
+def isuserxist(name):
+    cn = get_db_connection()
+    csr = cn.cursor()
+    csr.execute('SELECT * FROM users WHERE name = ?', (name,))
+    rst = csr.fetchone()
+    cn.close()
+    return rst is not None
+
+def ispsswdright(name, passwd):
+    cn = get_db_connection()
+    csr = cn.cursor()
+    csr.execute("SELECT passwd FROM users WHERE name = ?", (name,))
+    result = csr.fetchone()
+    cn.close()
+    return result and result[0] == passwd
+
+# 用户名验证函数
+def validate_username(username):
+    """验证用户名是否符合规则"""
+    # 长度在2-20个字符
+    if len(username) < 2 or len(username) > 20:
+        return False
+    
+    # 只能包含特定字符：字母、数字、_!@#$%^&+-~?
+    if not re.match(r'^[a-zA-Z0-9_!@#$%^&+\-~?]+$', username):
+        return False
+    
+    # 不能以数字开头
+    if username[0].isdigit():
+        return False
+    
+    return True
+
+# 修改获取头像函数
+def get_avatar(username):
+    cn = get_db_connection()
+    csr = cn.cursor()
+    csr.execute("SELECT avatar FROM users WHERE name = ?", (username,))
+    result = csr.fetchone()
+    cn.close()
+    if result:
+        avatar_file = result[0]
+        # 返回HTTP URL格式的头像路径
+        return f"/avatar/{username}/{avatar_file}"
+    
+    # 返回默认头像URL
+    return f"/avatar/default/{DEFAULT_AVATAR}"
+
+def register_user(usr, pwd, avatar="default_avatar.png"):
+    conn = get_db_connection()
+    try:
+        cursor = conn.cursor()
+        # 创建用户专属头像目录
+        user_avatar_dir = os.path.join(AVATAR_BASE_DIR, usr)
+        os.makedirs(user_avatar_dir, exist_ok=True)
+        cursor.execute("INSERT INTO users (name, passwd, avatar) VALUES (?, ?, ?)",
+                       (usr, pwd, avatar))
+        conn.commit()
+        return {"type": "register_1", "error": False, "message": "User registered successfully"}
+    except sqlite3.IntegrityError:
+        return {"type": "register_0", "success": False, "message": "Username already exists"}
+    except sqlite3.Error as e:
+        return {"type": "register_-1", "error": True, "message": str(e)}
+    finally:
+        conn.close()
+
+def generate_token(username):
+    token = secrets.token_hex(16)
+    tokens[token] = {'username': username, 'timestamp': time.time()}
+    return token
+
+def validate_token(token):
+    if token in tokens:
+        if time.time() - tokens[token]['timestamp'] < 3600:
+            tokens[token]['timestamp'] = time.time()
+            return tokens[token]['username']
+    return None
+
+@app.route("/api/register", methods=['POST'])
+def register1():
+    vl = request.get_json()
+    usr = vl.get('username')
+    pwd = vl.get('password')
+    avatar = vl.get('avatar', 'default_avatar.png')
+    
+    # 验证用户名
+    if not validate_username(usr):
+        return jsonify({
+            "type": "register_-2",
+            "success": False,
+            "message": "Invalid username. Must be 2-20 characters, start with a letter or symbol, and contain only letters, numbers, or symbols: _!@#$%^&+-~?"
+        }), 400
+
+    if avatar and not (avatar.endswith('.png') or avatar.endswith('.jpg')):
+        return jsonify({
+            "type": "register_0",
+            "success": False,
+            "message": "Invalid avatar format. Only .png or .jpg allowed"
+        }), 400
+
+    result = register_user(usr, pwd, avatar)
+    if result.get('success', True):  # 成功注册时返回的字典有'success'键
+        return jsonify(result)
+    else:
+        return jsonify(result), 403 if result['message'] == "Username already exists" else 500
+
+@app.route("/api/login", methods=['POST'])
+def login():
+    data = request.get_json()
+    username = data['username']
+
+    # 检查账号是否已登录
+    if username in active_connections:
+        # 检查连接是否仍然活跃
+        conn_info = active_connections[username]
+        try:
+            # 发送测试消息检查连接是否有效
+            conn_info['conn'].sendall(json.dumps({"type": "ping"}).encode('utf-8'))
+            logger.info(f"用户 {username} 的连接仍然活跃")
+            return jsonify({
+                "type": "login",
+                "status": "error_0",
+                "message": "Account already logged in"
+            }), 409
+        except:
+            # 连接已失效，清理旧连接
+            logger.warning(f"清理无效连接: {username}")
+            if username in active_connections:
+                del active_connections[username]
+            if conn_info['conn'] in chat_connections:
+                chat_connections.remove(conn_info['conn'])
+
+    if isuserxist(username) and ispsswdright(username, data['password']):
+        token = generate_token(username)
+        avatar = get_avatar(username)
+        return jsonify({
+            "type": "login_1",
+            "status": "success",
+            "token": token,
+            "avatar": avatar
+        })
+    return jsonify({
+        "type": "login_0",
+        "status": "error",
+        "message": "Invalid credentials"
+    }), 401
+
+# 添加头像静态路由
+@app.route("/avatar/<username>/<filename>", methods=['GET'])
+def serve_avatar(username, filename):
+    try:
+        avatar_dir = os.path.join(AVATAR_BASE_DIR, username)
+        return send_from_directory(avatar_dir, filename)
+    except FileNotFoundError:
+        # 如果找不到头像，返回默认头像
+        return send_from_directory(AVATAR_BASE_DIR, DEFAULT_AVATAR)
+
+@app.route("/api/chat", methods=['POST'])
+def chat():
+    token = request.headers.get('Authorization')
+    username = validate_token(token)
+    if not username:
+        return jsonify({"type": "chat", "status": "error"}), 401
+
+    data = request.get_json()
+    message = {
+        "type": "chat",
+        "user": username,
+        "message": data['message'],
+        "avatar": get_avatar(username)
+    }
+    broadcast_message(message)
+    return jsonify({"type": "chat", "status": "success"})
+
+def broadcast_message(message, sender=None):
+    for conn in chat_connections[:]:  # 使用副本迭代
+        try:
+            conn.sendall(json.dumps(message).encode('utf-8'))
+        except:
+            # 连接异常时移除
+            for uname, info in list(active_connections.items()):
+                if info['conn'] == conn:
+                    logger.warning(f"广播时移除无效连接: {uname}")
+                    del active_connections[uname]
+                    break
+            if conn in chat_connections:
+                chat_connections.remove(conn)
+
+def handle_socket_message(data, addr, conn):
+    try:
+        action = data.get('type')
+        if action == 'register':
+            username = data.get('username')
+            password = data.get('password')
+            avatar = data.get('avatar', 'default_avatar.png')
+            
+            # 验证用户名
+            if not validate_username(username):
+                response = {
+                    "type": "register_-2",
+                    "success": False,
+                    "message": "Invalid username format"
+                }
+                conn.sendall(json.dumps(response).encode('utf-8'))
+                return response
+
+            if avatar and not (avatar.endswith('.png') or avatar.endswith('.jpg')):
+                response = {
+                    "type": "register_-3",
+                    "success": False,
+                    "message": "Invalid avatar format. Only .png or .jpg allowed"
+                }
+                conn.sendall(json.dumps(response).encode('utf-8'))
+                return response
+
+            result = register_user(username, password, avatar)
+            conn.sendall(json.dumps(result).encode('utf-8'))
+            return result
+
+        elif action == 'login':
+            username = data['username']
+            password = data['password']
+
+            # 检查账号是否已登录且连接有效
+            if username in active_connections:
+                conn_info = active_connections[username]
+                try:
+                    # 测试连接是否仍然有效
+                    conn_info['conn'].sendall(json.dumps({"type": "ping"}).encode('utf-8'))
+                    logger.info(f"用户 {username} 尝试登录但已有活跃连接")
+                    response = {
+                        "type": "login",
+                        "status": "error_-1",
+                        "message": "Account already logged in"
+                    }
+                    conn.sendall(json.dumps(response).encode('utf-8'))
+                    return response
+                except:
+                    # 连接已失效，清理旧连接
+                    logger.warning(f"清理无效连接后允许登录: {username}")
+                    if username in active_connections:
+                        del active_connections[username]
+                    if conn_info['conn'] in chat_connections:
+                        chat_connections.remove(conn_info['conn'])
+
+            if isuserxist(username) and ispsswdright(username, password):
+                # 添加新连接
+                active_connections[username] = {'conn': conn, 'ip': addr[0], 'last_active': time.time()}
+                if conn not in chat_connections:
+                    chat_connections.append(conn)
+
+                token = generate_token(username)
+                avatar = get_avatar(username)
+                response = {
+                    "type": "login",
+                    "status": "success",
+                    "message": "Login successful",
+                    "token": token,
+                    "username": username,
+                    "avatar": avatar
+                }
+                conn.sendall(json.dumps(response).encode('utf-8'))
+                logger.info(f"用户 {username} 登录成功")
+                return response
+            else:
+                response = {
+                    "type": "login",
+                    "status": "error_0",
+                    "message": "Invalid credentials"
+                }
+                conn.sendall(json.dumps(response).encode('utf-8'))
+                return response
+
+        elif action == 'chat':
+            token = data.get('token')
+            if not token:
+                response = {
+                    "type": "chat",
+                    "status": "error_Mt",
+                    "message": "Missing token"
+                }
+                conn.sendall(json.dumps(response).encode('utf-8'))
+                return response
+
+            username = validate_token(token)
+            if not username:
+                response = {
+                    "type": "chat",
+                    "status": "error_It",
+                    "message": "Invalid token"
+                }
+                conn.sendall(json.dumps(response).encode('utf-8'))
+                return response
+
+            if username not in active_connections:
+                response = {
+                    "type": "chat",
+                    "status": "error_Nli",
+                    "message": "Not logged in"
+                }
+                conn.sendall(json.dumps(response).encode('utf-8'))
+                return response
+
+            # 更新最后活跃时间
+            active_connections[username]['last_active'] = time.time()
+
+            message = {
+                "type": "chat",
+                "user": username,
+                "message": data['message'],
+                "avatar": get_avatar(username)
+            }
+            broadcast_message(message)
+            response = {"type": "chat", "status": "success"}
+            conn.sendall(json.dumps(response).encode('utf-8'))
+            return response
+
+        elif action == 'heartbeat':
+            # 心跳检测
+            token = data.get('token')
+            if token:
+                username = validate_token(token)
+                if username and username in active_connections:
+                    # 更新最后活跃时间
+                    active_connections[username]['last_active'] = time.time()
+                    response = {"type": "heartbeat", "status": "success"}
+                    conn.sendall(json.dumps(response).encode('utf-8'))
+                    return response
+            return {"type": "heartbeat", "status": "error"}
+
+    except Exception as e:
+        logger.error(f"处理消息时出错: {str(e)}")
+        response = {
+            "status": "error",
+            "message": str(e)
+        }
+        try:
+            conn.sendall(json.dumps(response).encode('utf-8'))
+        except:
+            pass
+        return response
+
+def check_inactive_connections():
+    """定期检查不活跃的连接并清理"""
+    while True:
+        time.sleep(60)  # 每分钟检查一次
+        current_time = time.time()
+        inactive_users = []
+
+        for username, info in list(active_connections.items()):
+            # 5分钟无活动视为不活跃
+            if current_time - info['last_active'] > 300:
+                logger.warning(f"检测到不活跃用户: {username}, 最后活跃: {current_time - info['last_active']}秒前")
+                inactive_users.append(username)
+
+        for username in inactive_users:
+            info = active_connections[username]
+            try:
+                info['conn'].close()
+            except:
+                pass
+            if username in active_connections:
+                del active_connections[username]
+            if info['conn'] in chat_connections:
+                chat_connections.remove(info['conn'])
+            logger.info(f"已清理不活跃用户: {username}")
+
+def run_socket_server():
+    socket_server.bind(("0.0.0.0", 8889))
+    socket_server.listen()
+    logger.info("Socket server running on port 8889")
+
+    # 启动连接检查线程
+    threading.Thread(target=check_inactive_connections, daemon=True).start()
+
+    while True:
+        conn, addr = socket_server.accept()
+        logger.info(f"Socket client connected: {addr}")
+        try:
+            while True:
+                data = conn.recv(1024)
+                if not data:
+                    break
+
+                try:
+                    decoded_data = data.decode('utf-8', errors='ignore')
+                    json_data = json.loads(decoded_data)
+                    response = handle_socket_message(json_data, addr, conn)
+                except json.JSONDecodeError:
+                    response = {
+                        "type": "error",
+                        "status": "error",
+                        "message": "Invalid JSON"
+                    }
+                    conn.sendall(json.dumps(response).encode('utf-8'))
+                except Exception as e:
+                    logger.error(f"处理数据时出错: {str(e)}")
+                    response = {
+                        "type": "error",
+                        "status": "error",
+                        "message": str(e)
+                    }
+                    conn.sendall(json.dumps(response).encode('utf-8'))
+        except (ConnectionResetError, BrokenPipeError):
+            logger.warning(f"Client {addr} disconnected abruptly")
+        finally:
+            # 清理断开的连接
+            for username, info in list(active_connections.items()):
+                if info['conn'] == conn:
+                    del active_connections[username]
+                    logger.info(f"用户 {username} 断开连接")
+                    break
+
+            if conn in chat_connections:
+                chat_connections.remove(conn)
+
+            try:
+                conn.close()
+            except:
+                pass
+            logger.info(f"Connection closed for {addr}")
+
+if __name__ == '__main__':
+    with get_db_connection() as conn:
+        conn.execute('''CREATE TABLE IF NOT EXISTS users
+                      (name TEXT PRIMARY KEY, 
+                       passwd TEXT,
+                       avatar TEXT DEFAULT 'default_avatar.png')''')
+    # 确保头像目录存在
+    os.makedirs(AVATAR_BASE_DIR, exist_ok=True)
+    threading.Thread(target=run_socket_server, daemon=True).start()
+    app.run(port=5001, host='0.0.0.0')
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