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// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef NET_BASE_DATA_URL_H_
#define NET_BASE_DATA_URL_H_
#include <string>
#include <string_view>
#include "base/memory/scoped_refptr.h"
#include "net/base/net_errors.h"
#include "net/base/net_export.h"
class GURL;
namespace net {
class HttpResponseHeaders;
// This command line switch provides a means to disable data URL whitespace
// kKeepWhitespaceForDataUrls feature flag. This is set part of an enterprise
// policy and is intended as a kill switch.
inline constexpr std::string_view kRemoveWhitespaceForDataURLs =
"remove-keep-whitespace-for-data-urls";
// See RFC 2397 for a complete description of the 'data' URL scheme.
//
// Briefly, a 'data' URL has the form:
//
// data:[<mediatype>][;base64],<data>
//
// The <mediatype> is an Internet media type specification (with optional
// parameters.) The appearance of ";base64" means that the data is encoded as
// base64. Without ";base64", the data (as a sequence of octets) is represented
// using ASCII encoding for octets inside the range of safe URL characters and
// using the standard %xx hex encoding of URLs for octets outside that range.
// If <mediatype> is omitted, it defaults to text/plain;charset=US-ASCII. As a
// shorthand, "text/plain" can be omitted but the charset parameter supplied.
//
class NET_EXPORT DataURL {
public:
// This method can be used to parse a 'data' URL into its component pieces.
//
// |mime_type| and |charset| must be non-null and point to empty strings.
//
// If |data| is null, then the <data> section will not be parsed or validated.
// If non-null, it must point to an empty string.
//
// The resulting mime_type is normalized to lowercase. The data is the
// decoded data (e.g.., if the data URL specifies base64 encoding, then the
// returned data is base64 decoded, and any %-escaped bytes are unescaped).
//
// If the media type value doesn't match the media-type production defined in
// RFC 7231, mime_type will be set to the default value "text/plain". We
// don't simply fail for this grammar violation since Chromium had been
// accepting such invalid values. For example, <img> element with the src
// attribute set to a data URL with an invalid media type "image" (without a
// slash and subtype) had been displayed. However, the value this method will
// store in mime_type argument can be used for generating other headers, etc.
// This could lead to security vulnerability. We don't want to accept
// arbitrary value and ask each caller to validate the return value.
//
// If the charset parameter is specified but its value doesn't match the
// token production defined in RFC 7230, this method simply fails and returns
// false.
//
// If there's any other grammar violation in the URL, then this method will
// return false, and all passed in pointers will be unmodified. On success,
// true is returned.
[[nodiscard]] static bool Parse(const GURL& url,
std::string* mime_type,
std::string* charset,
std::string* data);
// Similar to parse, except that it also generates a bogus set of response
// headers, with Content-Type populated, and takes a method. Only the "HEAD"
// method modifies the response, resulting in a 0-length body. All arguments
// except must be non-null. All std::string pointers must point to empty
// strings, and |*headers| must be nullptr. Returns net::OK on success.
[[nodiscard]] static Error BuildResponse(
const GURL& url,
std::string_view method,
std::string* mime_type,
std::string* charset,
std::string* data,
scoped_refptr<HttpResponseHeaders>* headers);
};
} // namespace net
#endif // NET_BASE_DATA_URL_H_
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