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      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 }  // namespace net
     61 
     62 #endif  // NET_BASE_MIME_SNIFFER_H__
     63