206 lines
7.5 KiB
Markdown
206 lines
7.5 KiB
Markdown
# 修复邮件发送异常处理：MX记录验证 + 后端日志记录
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## 摘要
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当用户输入不存在域名的邮箱（如 `sync4@example.com`）时，QQ SMTP 服务器会接受邮件但后续产生 bounce，退信被发回 FROM 地址（`cs10086086@qq.com`）。由于 FROM 地址就是用户自己的 QQ 邮箱，用户收到了退信而非验证码。需要：
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1. 在发送邮件前验证邮箱域名有效性（MX 记录）
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2. 将异常信息记录到后端 ErrorLog，而不是让用户收到退信
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## 当前状态分析
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### 邮件发送流程
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```
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前端 → SendUserEmailAPIView → 储存验证码到 Redis → 返回成功 → submit_task (Celery) → _send_html_email → email.send() (QQ SMTP)
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↓
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SMTP 返回退信到 cs10086086@qq.com
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```
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### 现有 MX 验证情况
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| API 端点 | 文件位置 | MX 验证 |
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|:---|:---|:---|
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| `SendUserEmailAPIView` | `user/views/user.py:89` | **无** ❌ |
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| `ForgotPasswordSendCodeAPIView` | `user/views/user.py:276` | **有** ✅ (第 287 行) |
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| `SendChangeEmailCodeAPIView` | `user/views/email.py:37` | **无** ❌ |
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### 现有错误处理
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| 层级 | 文件 | 行为 |
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|:---|:---|:---|
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| View try/except | `user.py:132-137`, `email.py:96-102` | 返回 HTTP 500 + "邮件发送失败" |
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| `safe_task.py:submit_task` | `safe_task.py:28-45` | 超时降级同步；失败只记录 warning |
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| `_send_html_email` | `tasks.py:62-69` | **没有任何 try/except** - SMTP 异常直接穿透 |
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| Django LOGGING | `settings.py:298-338` | ERROR 级别 → `DatabaseErrorHandler` → `ErrorLog` 表 |
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### 根因
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1. `SendUserEmailAPIView` 缺少 MX 记录验证 — `ForgotPasswordSendCodeAPIView` 已有但未复用到其他端点
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2. QQ SMTP 对无效域名不会立即报错，而是在异步退信中通知 FROM 地址
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3. FROM 地址 (`cs10086086@qq.com`) 就是用户自己的邮箱，退信直接发给了用户
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4. `_send_html_email` 中 `email.send()` 没有任何异常捕获，即使 SMTP 抛异常也无法被妥善记录
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## 修改方案
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### 文件 1: `chunyu_project\user\tasks.py`
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**改动**：在 `_send_html_email` 中增加 try/except 捕获 SMTP 异常并记录日志
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```python
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# 修改前 (第 41-69 行)
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def _send_html_email(to_email, code, config_key):
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config = EMAIL_CONFIG[config_key]
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# ... 构建 email ...
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email.send()
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# 修改后
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def _send_html_email(to_email, code, config_key):
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import logging
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logger = logging.getLogger(__name__)
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config = EMAIL_CONFIG[config_key]
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# ... 构建 email (不变) ...
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try:
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email.send()
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except Exception as e:
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logger.error(
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f'[Email] SMTP send failed: to={to_email}, type={config_key}, error={str(e)}',
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exc_info=True
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)
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raise # 重新抛出，让 safe_task 的降级逻辑感知失败
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```
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### 文件 2: `chunyu_project\user\views\user.py`
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**改动**：在 `SendUserEmailAPIView` 中增加 MX 记录验证
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```python
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# 修改前 (第 89-137 行) - 直接发送，无 MX 验证
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def post(self, request):
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to_email = request.data.get('to_email', None)
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if to_email is None or to_email == "":
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return ...
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try:
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# 直接开始发送邮件
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...
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# 修改后 - 在发送前增加 MX 验证
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def post(self, request):
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to_email = request.data.get('to_email', None)
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if to_email is None or to_email == "":
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return create_standardized_error_response(
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code=ResponseCode.EMAIL_EMPTY,
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status_code=status.HTTP_400_BAD_REQUEST
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)
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# 新增：验证 MX 记录
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if not validate_email_mx(to_email):
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logger.warning(f'[Email] Domain MX check failed: email={to_email}')
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return create_standardized_error_response(
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code=ResponseCode.EMAIL_DOMAIN_INVALID,
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status_code=status.HTTP_400_BAD_REQUEST
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)
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try:
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# 原有发送逻辑不变
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...
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```
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**改动**：统一 `ForgotPasswordSendCodeAPIView` 的 MX 验证位置，保持在发送前
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此 API 已有 MX 验证（第 287-291 行），保持不动。无需修改。
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### 文件 3: `chunyu_project\user\views\email.py`
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**改动**：在 `SendChangeEmailCodeAPIView` 中增加 MX 记录验证
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```python
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# 修改前 (第 37-102 行) - 无 MX 验证
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def post(self, request):
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# captcha验证...
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serializer = SendEmailCodeSerializer(...)
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if not serializer.is_valid():
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return ...
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try:
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email = serializer.save() # save() 中调用 submit_task 发邮件
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...
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# 修改后 - 在 serializer 验证后、save 发送前增加 MX 验证
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def post(self, request):
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# captcha验证 (不变)...
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serializer = SendEmailCodeSerializer(data=request.data, context={'request': request})
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if not serializer.is_valid():
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return ...
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# 新增：MX 验证
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to_email = serializer.validated_data.get('email')
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if to_email and not validate_email_mx(to_email):
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logger.warning(f'[ChangeEmail] Domain MX check failed: email={to_email}')
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record_failure(operation, identifier)
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return create_standardized_error_response(
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code=ResponseCode.EMAIL_DOMAIN_INVALID,
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status_code=status.HTTP_400_BAD_REQUEST
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)
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try:
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email = serializer.save()
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...
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```
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注意：需要在 `email.py` 顶部导入 `validate_email_mx`：
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```python
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from ..views.user import validate_email_mx
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# 或将该函数提取到独立模块 utils/email_utils.py
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```
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### 文件 4 (可选优化): `chunyu_project\utils\safe_task.py`
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**改动**：增加 email-specific 的错误日志上下文
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当前 `submit_task` 降级失败时只记录 `logger.error('submit_task eager fallback failed...')`，可以增加邮件相关的上下文（发送目标、类型）。此项为可选优化，本次不做强制要求。
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### 文件 5 (推荐): 提取 `validate_email_mx` 到独立模块
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**改动**：将 `validate_email_mx` 从 `user/views/user.py` 提取到 `utils/email_utils.py`
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```python
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# 新建文件: chunyu_project/utils/email_utils.py
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import socket
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import logging
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logger = logging.getLogger(__name__)
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def validate_email_mx(email):
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"""验证邮箱域名是否有MX记录"""
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try:
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domain = email.split('@')[1]
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socket.getaddrinfo(domain, None, socket.AF_INET, socket.SOCK_STREAM)
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return True
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except (socket.gaierror, IndexError, Exception):
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logger.warning(f'MX record check failed for domain: {email}')
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return False
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```
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然后在 `user/views/user.py` 和 `user/views/email.py` 中导入：
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```python
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from utils.email_utils import validate_email_mx
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```
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## 修改汇总
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| 文件 | 改动类型 | 具体内容 |
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|:---|:---|:---|
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| `utils/email_utils.py` | **新建** | 提取 `validate_email_mx` 独立模块 |
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| `user/views/user.py` | 修改 | 删除本地 `validate_email_mx`；`SendUserEmailAPIView` 增加 MX 验证 |
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| `user/views/email.py` | 修改 | `SendChangeEmailCodeAPIView` 增加 MX 验证 |
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| `user/tasks.py` | 修改 | `_send_html_email` 增加 SMTP 异常捕获和日志 |
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## 验证步骤
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1. 用 `sync4@example.com` 测试 `POST /user/send_user_email/` → 应返回 `20023 EMAIL_DOMAIN_INVALID` 而非 200/201
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2. 用 `sync4@example.com` 测试 `POST /user/send_email_code/` → 应返回 `20023 EMAIL_DOMAIN_INVALID`
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3. 确认后端 ErrorLog 表中记录了 `[WARNING] Domain MX check failed` 日志
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4. 确认用户不再收到 SMTP 退信
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5. 用正常邮箱（如 `testuser@qq.com`）测试 → 功能不受影响，正常发送验证码
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