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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/url_request/redirect_util.h"
#include "base/check.h"
#include "base/memory/scoped_refptr.h"
#include "base/strings/stringprintf.h"
#include "net/http/http_request_headers.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_util.h"
#include "net/url_request/redirect_info.h"
#include "url/gurl.h"
#include "url/origin.h"
namespace net {
// static
void RedirectUtil::UpdateHttpRequest(
const GURL& original_url,
const std::string& original_method,
const RedirectInfo& redirect_info,
const std::optional<std::vector<std::string>>& removed_headers,
const std::optional<net::HttpRequestHeaders>& modified_headers,
HttpRequestHeaders* request_headers,
bool* should_clear_upload) {
DCHECK(request_headers);
DCHECK(should_clear_upload);
*should_clear_upload = false;
if (removed_headers) {
for (const std::string& key : removed_headers.value())
request_headers->RemoveHeader(key);
}
// The status code check and method updating to GET from step 12 of
// 4.4 HTTP-redirect fetch
// (https://fetch.spec.whatwg.org/#http-redirect-fetch) is handled in
// RedirectInfo::ComputeRedirectInfo. The remaining parts are implemented here
// by setting the flag to clear the request body and removing the
// "request-body-headers".
if (redirect_info.new_method != original_method) {
// TODO(davidben): This logic still needs to be replicated at the consumers.
//
// The Origin header is sent on anything that is not a GET or HEAD, which
// suggests all redirects that change methods (since they always change to
// GET) should drop the Origin header.
// See https://fetch.spec.whatwg.org/#origin-header
// TODO(jww): This is Origin header removal is probably layering violation
// and should be refactored into //content. See https://crbug.com/471397.
// See also: https://crbug.com/760487
request_headers->RemoveHeader(HttpRequestHeaders::kOrigin);
// This header should only be present further down the stack, but remove it
// here just in case.
request_headers->RemoveHeader(HttpRequestHeaders::kContentLength);
// These are "request-body-headers" and should be removed on redirects that
// change the method, per the fetch spec.
// https://fetch.spec.whatwg.org/
request_headers->RemoveHeader(HttpRequestHeaders::kContentType);
request_headers->RemoveHeader("Content-Encoding");
request_headers->RemoveHeader("Content-Language");
request_headers->RemoveHeader("Content-Location");
*should_clear_upload = true;
}
// Cross-origin redirects should not result in an Origin header value that is
// equal to the original request's Origin header. This is necessary to prevent
// a reflection of POST requests to bypass CSRF protections. If the header was
// not set to "null", a POST request from origin A to a malicious origin M
// could be redirected by M back to A.
//
// This behavior is specified in step 10 of the HTTP-redirect fetch
// algorithm[1] (which supercedes the behavior outlined in RFC 6454[2].
//
// [1]: https://fetch.spec.whatwg.org/#http-redirect-fetch
// [2]: https://tools.ietf.org/html/rfc6454#section-7
//
// TODO(crbug.com/471397, crbug.com/1406737): This is a layering violation and
// should be refactored somewhere into //net's embedder. Also, step 13 of
// https://fetch.spec.whatwg.org/#http-redirect-fetch is implemented in
// Blink.
if (!url::IsSameOriginWith(redirect_info.new_url, original_url) &&
request_headers->HasHeader(HttpRequestHeaders::kOrigin)) {
request_headers->SetHeader(HttpRequestHeaders::kOrigin,
url::Origin().Serialize());
}
if (modified_headers)
request_headers->MergeFrom(modified_headers.value());
}
// static
std::optional<std::string> RedirectUtil::GetReferrerPolicyHeader(
const HttpResponseHeaders* response_headers) {
if (!response_headers)
return std::nullopt;
return response_headers->GetNormalizedHeader("Referrer-Policy");
}
// static
scoped_refptr<HttpResponseHeaders> RedirectUtil::SynthesizeRedirectHeaders(
const GURL& redirect_destination,
ResponseCode response_code,
const std::string& redirect_reason,
const HttpRequestHeaders& request_headers) {
std::string header_string = base::StringPrintf(
"HTTP/1.1 %i Internal Redirect\n"
"Location: %s\n"
"Cross-Origin-Resource-Policy: Cross-Origin\n"
"Non-Authoritative-Reason: %s",
static_cast<int>(response_code), redirect_destination.spec().c_str(),
redirect_reason.c_str());
if (std::optional<std::string> http_origin =
request_headers.GetHeader("Origin");
http_origin) {
// If this redirect is used in a cross-origin request, add CORS headers to
// make sure that the redirect gets through. Note that the destination URL
// is still subject to the usual CORS policy, i.e. the resource will only
// be available to web pages if the server serves the response with the
// required CORS response headers.
header_string += base::StringPrintf(
"\n"
"Access-Control-Allow-Origin: %s\n"
"Access-Control-Allow-Credentials: true",
http_origin->c_str());
}
auto fake_headers = base::MakeRefCounted<HttpResponseHeaders>(
HttpUtil::AssembleRawHeaders(header_string));
DCHECK(fake_headers->IsRedirect(nullptr));
return fake_headers;
}
} // namespace net
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