Chrome Downloads API请求未被Declarative Net Request API修改的解决咨询

核心问题 #

使用Chrome扩展的Declarative Net Request API修改请求头时，通过chrome.downloads.download()发起的下载请求未被规则匹配，导致请求头未修改而下载失败；但通过DOM创建a标签触发的下载请求能正常被规则处理。

原因 #

Chrome的Downloads API发起的请求属于**download资源类型**，而你当前的静态规则中resourceTypes仅包含xmlhttprequest、main_frame、other，未覆盖download类型，因此规则不会对该类请求生效。

变通方案 #

方案1：扩展规则的资源类型范围 #

直接修改staticruleset.json中的resourceTypes，添加download类型，让规则匹配Downloads API发起的请求：

{
  "id": 6413,
  "priority": 3,
  "action": {
    "type": "modifyHeaders",
    "requestHeaders": [
      { "header": "Origin", "operation": "remove" },
      {"header": "Sec-Fetch-Site", "operation": "set", "value": "same-origin" },
      { "header": "Sec-Fetch-Mode", "operation": "set", "value": "navigate" },
      { "header": "Sec-Fetch-Dest", "operation": "set", "value": "document" },
      { "header": "Sec-Fetch-User", "operation": "set", "value": "?1" }
    ]
  },
  "condition": {
    "urlFilter": "example.com/downloads/",
    "resourceTypes": ["xmlhttprequest", "main_frame", "other", "download"]
  }
}

方案2：新增单独针对Downloads API的规则 #

如果不想让原规则覆盖过多资源类型，可以新增一条优先级相同或更高的规则，专门匹配download类型：

{
  "id": 6414,
  "priority": 3,
  "action": {
    "type": "modifyHeaders",
    "requestHeaders": [
      { "header": "Origin", "operation": "remove" },
      {"header": "Sec-Fetch-Site", "operation": "set", "value": "same-origin" },
      { "header": "Sec-Fetch-Mode", "operation": "set", "value": "navigate" },
      { "header": "Sec-Fetch-Dest", "operation": "set", "value": "document" },
      { "header": "Sec-Fetch-User", "operation": "set", "value": "?1" }
    ]
  },
  "condition": {
    "urlFilter": "example.com/downloads/",
    "resourceTypes": ["download"]
  }
}

验证步骤 #

1. 修改规则后，重新加载Chrome扩展（在chrome://extensions/页面点击刷新按钮）
2. 使用chrome://net-export再次捕获请求日志，确认Downloads API发起的请求已被规则修改请求头
3. 测试下载功能，确认请求符合服务器要求并成功下载

内容的提问来源于stack exchange，提问作者user23341070