net/base/mime_sniffer.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_BASE_MIME_SNIFFER_H__
   6 #define NET_BASE_MIME_SNIFFER_H__
   7
   8 #include <string>
   9
  10 #include "net/base/net_export.h"
  11
  12 class GURL;
  13
  14 namespace net {
  15
  16 // The maximum number of bytes used by any internal mime sniffing routine. May
  17 // be useful for callers to determine an efficient buffer size to pass to
  18 // |SniffMimeType|.
  19 // This must be updated if any internal sniffing routine needs more bytes.
  20 const int kMaxBytesToSniff = 1024;
  21
  22 // Examine the URL and the mime_type and decide whether we should sniff a
  23 // replacement mime type from the content.
  24 //
  25 // @param url The URL from which we obtained the content.
  26 // @param mime_type The current mime type, e.g. from the Content-Type header.
  27 // @return Returns true if we should sniff the mime type.
  28 NET_EXPORT bool ShouldSniffMimeType(const GURL& url,
  29                                     const std::string& mime_type);
  30
  31 // Guess a mime type from the first few bytes of content an its URL.  Always
  32 // assigns |result| with its best guess of a mime type.
  33 //
  34 // @param content A buffer containing the bytes to sniff.
  35 // @param content_size The number of bytes in the |content| buffer.
  36 // @param url The URL from which we obtained this content.
  37 // @param type_hint The current mime type, e.g. from the Content-Type header.
  38 // @param result Address at which to place the sniffed mime type.
  39 // @return Returns true if we have enough content to guess the mime type.
  40 NET_EXPORT bool SniffMimeType(const char* content, size_t content_size,
  41                               const GURL& url, const std::string& type_hint,
  42                               std::string* result);
  43
  44 // Attempt to identify a MIME type from the first few bytes of content only.
  45 // Uses a bigger set of media file searches than |SniffMimeType()|.
  46 // If finds a match, fills in |result| and returns true,
  47 // otherwise returns false.
  48 //
  49 // The caller should understand the security ramifications of trusting
  50 // uncontrolled data before accepting the results of this function.
  51 //
  52 // @param content A buffer containing the bytes to sniff.
  53 // @param content_size The number of bytes in the |content| buffer.
  54 // @param result Address at which to place the sniffed mime type.
  55 // @return Returns true if a MIME type match was found.
  56 NET_EXPORT bool SniffMimeTypeFromLocalData(const char* content,
  57                                            size_t content_size,
  58                                            std::string* result);
  59
  60 // Returns true if |content| contains bytes that are control codes that do
  61 // not usually appear in plain text.
  62 // @param content A buffer contains bytes that may be binary.
  63 // @param size    The number of bytes in the |content| buffer.
  64 // @return Returns true if |content| looks like binary.
  65 NET_EXPORT_PRIVATE bool LooksLikeBinary(const char* content, size_t size);
  66
  67 }  // namespace net
  68
  69 #endif  // NET_BASE_MIME_SNIFFER_H__