netwerk/streamconv/converters/nsUnknownDecoder.h

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  37
  38 #ifndef nsUnknownDecoder_h__
  39 #define nsUnknownDecoder_h__
  40
  41 #include "nsIStreamConverter.h"
  42 #include "nsIChannel.h"
  43 #include "nsIContentSniffer.h"
  44 #include "nsIGenericFactory.h"
  45
  46 #include "nsCOMPtr.h"
  47 #include "nsString.h"
  48
  49 #define NS_UNKNOWNDECODER_CID                        \
  50 { /* 7d7008a0-c49a-11d3-9b22-0080c7cb1080 */         \
  51     0x7d7008a0,                                      \
  52     0xc49a,                                          \
  53     0x11d3,                                          \
  54     {0x9b, 0x22, 0x00, 0x80, 0xc7, 0xcb, 0x10, 0x80}       \
  55 }
  56
  57
  58 class nsUnknownDecoder : public nsIStreamConverter, public nsIContentSniffer
  59 {
  60 public:
  61   // nsISupports methods
  62   NS_DECL_ISUPPORTS
  63
  64   // nsIStreamConverter methods
  65   NS_DECL_NSISTREAMCONVERTER
  66
  67   // nsIStreamListener methods
  68   NS_DECL_NSISTREAMLISTENER
  69
  70   // nsIRequestObserver methods
  71   NS_DECL_NSIREQUESTOBSERVER
  72
  73   // nsIContentSniffer methods
  74   NS_DECL_NSICONTENTSNIFFER
  75
  76   nsUnknownDecoder();
  77
  78 protected:
  79   virtual ~nsUnknownDecoder();
  80
  81   virtual void DetermineContentType(nsIRequest* aRequest);
  82   nsresult FireListenerNotifications(nsIRequest* request, nsISupports *aCtxt);
  83
  84 protected:
  85   nsCOMPtr<nsIStreamListener> mNextListener;
  86
  87   // Function to use to check whether sniffing some potentially
  88   // dangerous types (eg HTML) is ok for this request.  We can disable
  89   // sniffing for local files if needed using this.  Just a security
  90   // precation thingy... who knows when we suddenly need to flip this
  91   // pref?
  92   PRBool AllowSniffing(nsIRequest* aRequest);
  93
  94   // Various sniffer functions.  Returning PR_TRUE means that a type
  95   // was determined; PR_FALSE means no luck.
  96   PRBool TryContentSniffers(nsIRequest* aRequest);
  97   PRBool SniffForHTML(nsIRequest* aRequest);
  98   PRBool SniffForXML(nsIRequest* aRequest);
  99
 100   // SniffURI guesses at the content type based on the URI (typically
 101   // using the extentsion)
 102   PRBool SniffURI(nsIRequest* aRequest);
 103
 104   // LastDitchSniff guesses at text/plain vs. application/octet-stream
 105   // by just looking at whether the data contains null bytes, and
 106   // maybe at the fraction of chars with high bit set.  Use this only
 107   // as a last-ditch attempt to decide a content type!
 108   PRBool LastDitchSniff(nsIRequest* aRequest);
 109
 110   /**
 111    * An entry struct for our array of sniffers.  Each entry has either
 112    * a type associated with it (set these with the SNIFFER_ENTRY macro)
 113    * or a function to be executed (set these with the
 114    * SNIFFER_ENTRY_WITH_FUNC macro).  The function should take a single
 115    * nsIRequest* and returns PRBool -- PR_TRUE if it sets mContentType,
 116    * PR_FALSE otherwise
 117    */
 118   struct nsSnifferEntry {
 119     typedef PRBool (nsUnknownDecoder::*TypeSniffFunc)(nsIRequest* aRequest);
 120
 121     const char* mBytes;
 122     PRUint32 mByteLen;
 123
 124     // Exactly one of mMimeType and mContentTypeSniffer should be set non-null
 125     const char* mMimeType;
 126     TypeSniffFunc mContentTypeSniffer;
 127   };
 128
 129 #define SNIFFER_ENTRY(_bytes, _type) \
 130   { _bytes, sizeof(_bytes) - 1, _type, nsnull }
 131
 132 #define SNIFFER_ENTRY_WITH_FUNC(_bytes, _func) \
 133   { _bytes, sizeof(_bytes) - 1, nsnull, _func }
 134
 135   static nsSnifferEntry sSnifferEntries[];
 136   static PRUint32 sSnifferEntryNum;
 137
 138   char *mBuffer;
 139   PRUint32 mBufferLen;
 140   PRBool mRequireHTMLsuffix;
 141
 142   nsCString mContentType;
 143
 144 };
 145
 146 #define NS_BINARYDETECTOR_CID                        \
 147 { /* a2027ec6-ba0d-4c72-805d-148233f5f33c */         \
 148     0xa2027ec6,                                      \
 149     0xba0d,                                          \
 150     0x4c72,                                          \
 151     {0x80, 0x5d, 0x14, 0x82, 0x33, 0xf5, 0xf3, 0x3c} \
 152 }
 153
 154 /**
 155  * Class that detects whether a data stream is text or binary.  This reuses
 156  * most of nsUnknownDecoder except the actual content-type determination logic
 157  * -- our overridden DetermineContentType simply calls LastDitchSniff and sets
 158  * the type to APPLICATION_GUESS_FROM_EXT if the data is detected as binary.
 159  */
 160 class nsBinaryDetector : public nsUnknownDecoder
 161 {
 162 public:
 163   static NS_METHOD Register(nsIComponentManager* compMgr, nsIFile* path,
 164                             const char* registryLocation,
 165                             const char* componentType,
 166                             const nsModuleComponentInfo *info);
 167
 168 protected:
 169   virtual void DetermineContentType(nsIRequest* aRequest);
 170 };
 171
 172 #endif /* nsUnknownDecoder_h__ */
 173