场景描述

A 站点 HTTPS，A 站点做为中心站，引用 B/C/D/E/F……站点的资源进行供给，确定的只有 A 站点是 HTTPS，其它站点可能是 HTTP 也可能是 HTTPS，文件类型不限定，包括但不限于：CSS,JS,IMAGE,MP4,MP3,RAR,ZIP,M3U8,FLV……。

如果你使用的是默认配置，那么它会提示以下错误：

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Access to XMLHttpRequest at 'http://site.com/index.m3u8' from origin 'http://site' has been blocked by CORS policy: The response is invalid.

知道通常情况下，HTTPS 引用 HTTP 的资源就会出现跨域错误，但今天我们的要求是允许它跨域，并且尽量保证它是基本安全的。

在上周我测试过很多方案，最终使用的是：

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add_header Content-Security-Policy "upgrade-insecure-requests";

意思是将所有 HTTP 请求尽可能的转换成 HTTPS 请求，如果对方同时支持 HTTPS 和 HTTP 协议，那这没有任何问题，但如果对方只支持 HTTP，那这时候就会报错：

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Refused to load the image 'http://site/file.png'
because it violates the following Content Security Policy directive:

看到提示后直觉告诉我要去放行img-src和media-src，但当我去放行设置后，问题依旧，甚至还多出了错误。

Content-Security-Policy 内容安全策略

内容安全策略（CSP）需要仔细调整和精确定义策略。如果启用，CSP 会对浏览器呈现页面的方式产生重大影响（例如，默认情况下禁用内联 JavaScript，并且必须在策略中明确允许）。CSP 可防止各种攻击，包括跨站点脚本和其他跨站点注入。

Values

Directive Description
base-uri Define the base uri for relative uri.
default-src Define loading policy for all resources type in case of a resource type dedicated directive is not defined (fallback).
script-src Define which scripts the protected resource can execute.
object-src Define from where the protected resource can load plugins.
style-src Define which styles (CSS) the user applies to the protected resource.
img-src Define from where the protected resource can load images.
media-src Define from where the protected resource can load video and audio.
frame-src Deprecated and replaced by child-src. Define from where the protected resource can embed frames.
child-src Define from where the protected resource can embed frames.
frame-ancestors Define from where the protected resource can be embedded in frames.
font-src Define from where the protected resource can load fonts.
connect-src Define which URIs the protected resource can load using script interfaces.
manifest-src Define from where the protected resource can load manifest.
form-action Define which URIs can be used as the action of HTML form elements.
sandbox Specifies an HTML sandbox policy that the user agent applies to the protected resource.
script-nonce Define script execution by requiring the presence of the specified nonce on script elements.
plugin-types Define the set of plugins that can be invoked by the protected resource by limiting the types of resources that can be embedded.
reflected-xss Instructs a user agent to activate or deactivate any heuristics used to filter or block reflected cross-site scripting attacks, equivalent to the effects of the non-standard X-XSS-Protection header.
block-all-mixed-content Prevent user agent from loading mixed content.
upgrade-insecure-requests Instructs user agent to download insecure resources using HTTPS.
referrer Define information user agent must send in Referer header.
report-uri Specifies a URI to which the user agent sends reports about policy violation.
report-to Specifies a group (defined in Report-To header) to which the user agent sends reports about policy violation.

Example

Content-Security-Policy: script-src 'self'

在经过反复测试后

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add_header Content-Security-Policy "upgrade-insecure-requests;connect-src *";

解决了全部问题，即消除全部警告，同时兼容了各种协议资源。

参考