56 lines
1.9 KiB
Go
56 lines
1.9 KiB
Go
package responsemodifers
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import (
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_ "embed"
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"fmt"
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"ladder/proxychain"
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"ladder/proxychain/responsemodifers/rewriters"
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"strings"
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)
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//go:embed patch_dynamic_resource_urls.js
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var patchDynamicResourceURLsScript string
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// PatchDynamicResourceURLs patches the javascript runtime to rewrite URLs client-side.
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// - This function is designed to allow the proxified page
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// to still be browsible by routing all resource URLs through the proxy.
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// - Native APIs capable of network requests will be hooked
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// and the URLs arguments modified to point to the proxy instead.
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// - fetch('/relative_path') -> fetch('/https://proxiedsite.com/relative_path')
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// - Element.setAttribute('src', "/assets/img.jpg") -> Element.setAttribute('src', "/https://proxiedsite.com/assets/img.jpg") -> fetch('/https://proxiedsite.com/relative_path')
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func PatchDynamicResourceURLs() proxychain.ResponseModification {
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return func(chain *proxychain.ProxyChain) error {
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// don't add rewriter if it's not even html
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ct := chain.Response.Header.Get("content-type")
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if !strings.HasPrefix(ct, "text/html") {
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return nil
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}
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// this is the original URL sent by client:
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// http://localhost:8080/http://proxiedsite.com/foo/bar
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originalURI := chain.Context.Request().URI()
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// this is the extracted URL that the client requests to proxy
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// http://proxiedsite.com/foo/bar
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reqURL := chain.Request.URL
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params := map[string]string{
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// ie: http://localhost:8080
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"{{PROXY_ORIGIN}}": fmt.Sprintf("%s://%s", originalURI.Scheme(), originalURI.Host()),
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// ie: http://proxiedsite.com
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"{{ORIGIN}}": fmt.Sprintf("%s://%s", reqURL.Scheme, reqURL.Host),
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}
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rr := rewriters.NewScriptInjectorRewriterWithParams(
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patchDynamicResourceURLsScript,
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rewriters.BeforeDOMContentLoaded,
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params,
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)
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htmlRewriter := rewriters.NewHTMLRewriter(chain.Response.Body, rr)
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chain.Response.Body = htmlRewriter
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return nil
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}
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}
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