Source/WebKitLegacy/mac/Misc/WebNSDataExtras.mm - WebKit - Git at Google

 /*
  * Copyright (C) 2005-2018 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */

 #import <WebKitLegacy/WebNSDataExtras.h>
 #import <WebKitLegacy/WebNSDataExtrasPrivate.h>

 #import <wtf/Assertions.h>

 @interface NSString (WebNSDataExtrasInternal)
 - (NSString *)_web_capitalizeRFC822HeaderFieldName;
 @end

 @implementation NSString (WebNSDataExtrasInternal)

 - (NSString *)_web_capitalizeRFC822HeaderFieldName
 {
     CFStringRef name = (CFStringRef)self;
     NSString *result = nil;

     CFIndex len = CFStringGetLength(name);
     char* charPtr = nullptr;
     UniChar* uniCharPtr = nullptr;
     Boolean useUniCharPtr = FALSE;
     Boolean shouldCapitalize = TRUE;
     Boolean somethingChanged = FALSE;

     for (CFIndex i = 0; i < len; i ++) {
         UniChar ch = CFStringGetCharacterAtIndex(name, i);
         Boolean replace = FALSE;
         if (shouldCapitalize && ch >= 'a' && ch <= 'z') {
             ch = ch + 'A' - 'a';
             replace = TRUE;
         } else if (!shouldCapitalize && ch >= 'A' && ch <= 'Z') {
             ch = ch + 'a' - 'A';
             replace = TRUE;
         }
         if (replace) {
             if (!somethingChanged) {
                 somethingChanged = TRUE;
                 if (CFStringGetBytes(name, CFRangeMake(0, len), kCFStringEncodingISOLatin1, 0, FALSE, NULL, 0, NULL) == len) {
                     // Can be encoded in ISOLatin1
                     useUniCharPtr = FALSE;
                     charPtr = static_cast<char*>(CFAllocatorAllocate(kCFAllocatorDefault, len + 1, 0));
                     CFStringGetCString(name, charPtr, len+1, kCFStringEncodingISOLatin1);
                 } else {
                     useUniCharPtr = TRUE;
                     uniCharPtr = static_cast<UniChar*>(CFAllocatorAllocate(kCFAllocatorDefault, len * sizeof(UniChar), 0));
                     CFStringGetCharacters(name, CFRangeMake(0, len), uniCharPtr);
                 }
             }
             if (useUniCharPtr)
                 uniCharPtr[i] = ch;
             else
                 charPtr[i] = ch;
         }
         if (ch == '-')
             shouldCapitalize = TRUE;
         else
             shouldCapitalize = FALSE;
     }
     if (somethingChanged) {
         if (useUniCharPtr)
             result = (NSString *)CFStringCreateWithCharactersNoCopy(NULL, uniCharPtr, len, NULL);
         else
             result = (NSString *)CFStringCreateWithCStringNoCopy(NULL, charPtr, kCFStringEncodingISOLatin1, NULL);
     } else
         result = [self retain];

     return [result autorelease];
 }

 @end

 @implementation NSData (WebKitExtras)

 - (NSString *)_webkit_guessedMIMETypeForXML
 {
     NSUInteger length = [self length];
     const UInt8* bytes = static_cast<const UInt8*>([self bytes]);

 #define CHANNEL_TAG_LENGTH 7

     const char* p = reinterpret_cast<const char*>(bytes);
     int remaining = std::min<NSUInteger>(length, WEB_GUESS_MIME_TYPE_PEEK_LENGTH) - (CHANNEL_TAG_LENGTH - 1);

     BOOL foundRDF = false;

     while (remaining > 0) {
         // Look for a "<".
         const char* hit = static_cast<const char*>(memchr(p, '<', remaining));
         if (!hit)
             break;

         // We are trying to identify RSS or Atom. RSS has a top-level
         // element of either <rss> or <rdf>. However, there are
         // non-RSS RDF files, so in the case of <rdf> we further look
         // for a <channel> element. In the case of an Atom file, a
         // top-level <feed> element is all we need to see. Only tags
         // starting with <? or <! can precede the root element. We
         // bail if we don't find an <rss>, <feed> or <rdf> element
         // right after those.

         if (foundRDF) {
             if (!strncasecmp(hit, "<channel", strlen("<channel")))
                 return @"application/rss+xml";
         } else if (!strncasecmp(hit, "<rdf", strlen("<rdf")))
             foundRDF = TRUE;
         else if (!strncasecmp(hit, "<rss", strlen("<rss")))
             return @"application/rss+xml";
         else if (!strncasecmp(hit, "<feed", strlen("<feed")))
             return @"application/atom+xml";
         else if (strncasecmp(hit, "<?", strlen("<?")) && strncasecmp(hit, "<!", strlen("<!")))
             return nil;

         // Skip the "<" and continue.
         remaining -= (hit + 1) - p;
         p = hit + 1;
     }

     return nil;
 }

 - (NSString *)_webkit_guessedMIMEType
 {
 #define JPEG_MAGIC_NUMBER_LENGTH 4
 #define SCRIPT_TAG_LENGTH 7
 #define TEXT_HTML_LENGTH 9
 #define VCARD_HEADER_LENGTH 11
 #define VCAL_HEADER_LENGTH 15

     NSString *MIMEType = [self _webkit_guessedMIMETypeForXML];
     if ([MIMEType length])
         return MIMEType;

     NSUInteger length = [self length];
     const char* bytes = static_cast<const char*>([self bytes]);

     const char* p = bytes;
     int remaining = std::min<NSUInteger>(length, WEB_GUESS_MIME_TYPE_PEEK_LENGTH) - (SCRIPT_TAG_LENGTH - 1);
     while (remaining > 0) {
         // Look for a "<".
         const char* hit = static_cast<const char*>(memchr(p, '<', remaining));
         if (!hit)
             break;

         // If we found a "<", look for "<html>" or "<a " or "<script".
         if (!strncasecmp(hit, "<html>", strlen("<html>"))
             || !strncasecmp(hit, "<a ", strlen("<a "))
             || !strncasecmp(hit, "<script", strlen("<script"))
             || !strncasecmp(hit, "<title>", strlen("<title>"))) {
             return @"text/html";
         }

         // Skip the "<" and continue.
         remaining -= (hit + 1) - p;
         p = hit + 1;
     }

     // Test for a broken server which has sent the content type as part of the content.
     // This code could be improved to look for other mime types.
     p = bytes;
     remaining = std::min<NSUInteger>(length, WEB_GUESS_MIME_TYPE_PEEK_LENGTH) - (TEXT_HTML_LENGTH - 1);
     while (remaining > 0) {
         // Look for a "t" or "T".
         const char* hit = nullptr;
         const char* lowerhit = static_cast<const char*>(memchr(p, 't', remaining));
         const char* upperhit = static_cast<const char*>(memchr(p, 'T', remaining));
         if (!lowerhit && !upperhit)
             break;

         if (!lowerhit)
             hit = upperhit;
         else if (!upperhit)
             hit = lowerhit;
         else
             hit = std::min<const char*>(lowerhit, upperhit);

         // If we found a "t/T", look for "text/html".
         if (!strncasecmp(hit, "text/html", TEXT_HTML_LENGTH))
             return @"text/html";

         // Skip the "t/T" and continue.
         remaining -= (hit + 1) - p;
         p = hit + 1;
     }

     if ((length >= VCARD_HEADER_LENGTH) && !strncmp(bytes, "BEGIN:VCARD", VCARD_HEADER_LENGTH))
         return @"text/vcard";
     if ((length >= VCAL_HEADER_LENGTH) && !strncmp(bytes, "BEGIN:VCALENDAR", VCAL_HEADER_LENGTH))
         return @"text/calendar";

     // Test for plain text.
     NSUInteger i;
     for (i = 0; i < length; ++i) {
         char c = bytes[i];
         if ((c < 0x20 || c > 0x7E) && (c != '\t' && c != '\r' && c != '\n'))
             break;
     }
     if (i == length) {
         // Didn't encounter any bad characters, looks like plain text.
         return @"text/plain";
     }

     // Looks like this is a binary file.

     // Sniff for the JPEG magic number.
     if ((length >= JPEG_MAGIC_NUMBER_LENGTH) && !strncmp(bytes, "\xFF\xD8\xFF\xE0", JPEG_MAGIC_NUMBER_LENGTH))
         return @"image/jpeg";

 #undef JPEG_MAGIC_NUMBER_LENGTH
 #undef SCRIPT_TAG_LENGTH
 #undef TEXT_HTML_LENGTH
 #undef VCARD_HEADER_LENGTH
 #undef VCAL_HEADER_LENGTH

     return nil;
 }

 @end

 @implementation NSData (WebNSDataExtras)

 - (BOOL)_web_isCaseInsensitiveEqualToCString:(const char *)string
 {
     ASSERT(string);

     const char* bytes = static_cast<const char*>([self bytes]);
     return !strncasecmp(bytes, string, [self length]);
 }

 static const UInt8 *_findEOL(const UInt8 *bytes, CFIndex len)
 {
     // According to the HTTP specification EOL is defined as
     // a CRLF pair. Unfortunately, some servers will use LF
     // instead. Worse yet, some servers will use a combination
     // of both (e.g. <header>CRLFLF<body>), so findEOL needs
     // to be more forgiving. It will now accept CRLF, LF, or
     // CR.
     //
     // It returns NULL if EOL is not found or it will return
     // a pointer to the first terminating character.
     for (CFIndex i = 0;  i < len; i++) {
         UInt8 c = bytes[i];
         if ('\n' == c)
             return bytes + i;
         if ('\r' == c) {
             // Check to see if spanning buffer bounds
             // (CRLF is across reads). If so, wait for
             // next read.
             if (i + 1 == len)
                 break;

             return bytes + i;
         }
     }

     return nullptr;
 }

 - (NSMutableDictionary *)_webkit_parseRFC822HeaderFields
 {
     NSMutableDictionary *headerFields = [NSMutableDictionary dictionary];

     const UInt8* bytes = static_cast<const UInt8*>([self bytes]);
     NSUInteger length = [self length];
     NSString *lastKey = nil;
     const UInt8 *eol;

     // Loop over lines until we're past the header, or we can't find any more end-of-lines
     while ((eol = _findEOL(bytes, length))) {
         const UInt8 *line = bytes;
         SInt32 lineLength = eol - bytes;

         // Move bytes to the character after the terminator as returned by _findEOL.
         bytes = eol + 1;
         if (('\r' == *eol) && ('\n' == *bytes))
             bytes++; // Safe since _findEOL won't return a spanning CRLF.

         length -= (bytes - line);
         if (!lineLength) {
             // Blank line; we're at the end of the header
             break;
         }
         if (*line == ' ' || *line == '\t') {
             // Continuation of the previous header
             if (!lastKey) {
                 // malformed header; ignore it and continue
                 continue;
             }
             // Merge the continuation of the previous header
             NSString *currentValue = [headerFields objectForKey:lastKey];
             NSString *newValue = (NSString *)CFStringCreateWithBytes(NULL, line, lineLength, kCFStringEncodingISOLatin1, FALSE);
             ASSERT(currentValue);
             ASSERT(newValue);
             NSString *mergedValue = [[NSString alloc] initWithFormat:@"%@%@", currentValue, newValue];
             [headerFields setObject:(NSString *)mergedValue forKey:lastKey];
             [newValue release];
             [mergedValue release];
             // Note: currentValue is autoreleased
         } else {
             // Brand new header
             const UInt8 *colon;
             for (colon = line; *colon != ':' && colon != eol; colon++) { }
             if (colon == eol) {
                 // malformed header; ignore it and continue
                 continue;
             }
             lastKey = (NSString *)CFStringCreateWithBytes(NULL, line, colon - line, kCFStringEncodingISOLatin1, FALSE);
             [lastKey autorelease];
             NSString *value = [lastKey _web_capitalizeRFC822HeaderFieldName];
             lastKey = value;
             for (colon++; colon != eol; colon++) {
                 if (*colon != ' ' && *colon != '\t')
                     break;
             }
             if (colon == eol) {
                 value = [[NSString alloc] initWithString:@""];
                 [value autorelease];
             } else {
                 value = (NSString *)CFStringCreateWithBytes(NULL, colon, eol-colon, kCFStringEncodingISOLatin1, FALSE);
                 [value autorelease];
             }
             NSString *oldValue = [headerFields objectForKey:lastKey];
             if (oldValue) {
                 NSString *newValue = [[NSString alloc] initWithFormat:@"%@, %@", oldValue, value];
                 value = newValue;
                 [newValue autorelease];
             }
             [headerFields setObject:(NSString *)value forKey:lastKey];
         }
     }

     return headerFields;
 }

 - (BOOL)_web_startsWithBlankLine
 {
     return [self length] > 0 && ((const char *)[self bytes])[0] == '\n';
 }

 - (NSInteger)_web_locationAfterFirstBlankLine
 {
     const char *bytes = (const char *)[self bytes];
     NSUInteger length = [self length];

     unsigned i;
     for (i = 0; i < length - 4; i++) {

         //  Support for Acrobat. It sends "\n\n".
         if (bytes[i] == '\n' && bytes[i+1] == '\n')
             return i+2;

         // Returns the position after 2 CRLF's or 1 CRLF if it is the first line.
         if (bytes[i] == '\r' && bytes[i+1] == '\n') {
             i += 2;
             if (i == 2)
                 return i;
             if (bytes[i] == '\n') {
                 // Support for Director. It sends "\r\n\n" (3880387).
                 return i+1;
             }
             if (bytes[i] == '\r' && bytes[i+1] == '\n') {
                 // Support for Flash. It sends "\r\n\r\n" (3758113).
                 return i+2;
             }
         }
     }
     return NSNotFound;
 }

 @end
	/*
	* Copyright (C) 2005-2018 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
	* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
	* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#import <WebKitLegacy/WebNSDataExtras.h>
	#import <WebKitLegacy/WebNSDataExtrasPrivate.h>

	#import <wtf/Assertions.h>

	@interface NSString (WebNSDataExtrasInternal)
	- (NSString *)_web_capitalizeRFC822HeaderFieldName;
	@end

	@implementation NSString (WebNSDataExtrasInternal)

	- (NSString *)_web_capitalizeRFC822HeaderFieldName
	{
	CFStringRef name = (CFStringRef)self;
	NSString *result = nil;

	CFIndex len = CFStringGetLength(name);
	char* charPtr = nullptr;
	UniChar* uniCharPtr = nullptr;
	Boolean useUniCharPtr = FALSE;
	Boolean shouldCapitalize = TRUE;
	Boolean somethingChanged = FALSE;

	for (CFIndex i = 0; i < len; i ++) {
	UniChar ch = CFStringGetCharacterAtIndex(name, i);
	Boolean replace = FALSE;
	if (shouldCapitalize && ch >= 'a' && ch <= 'z') {
	ch = ch + 'A' - 'a';
	replace = TRUE;
	} else if (!shouldCapitalize && ch >= 'A' && ch <= 'Z') {
	ch = ch + 'a' - 'A';
	replace = TRUE;
	}
	if (replace) {
	if (!somethingChanged) {
	somethingChanged = TRUE;
	if (CFStringGetBytes(name, CFRangeMake(0, len), kCFStringEncodingISOLatin1, 0, FALSE, NULL, 0, NULL) == len) {
	// Can be encoded in ISOLatin1
	useUniCharPtr = FALSE;
	charPtr = static_cast<char*>(CFAllocatorAllocate(kCFAllocatorDefault, len + 1, 0));
	CFStringGetCString(name, charPtr, len+1, kCFStringEncodingISOLatin1);
	} else {
	useUniCharPtr = TRUE;
	uniCharPtr = static_cast<UniChar>(CFAllocatorAllocate(kCFAllocatorDefault, len sizeof(UniChar), 0));
	CFStringGetCharacters(name, CFRangeMake(0, len), uniCharPtr);
	}
	}
	if (useUniCharPtr)
	uniCharPtr[i] = ch;
	else
	charPtr[i] = ch;
	}
	if (ch == '-')
	shouldCapitalize = TRUE;
	else
	shouldCapitalize = FALSE;
	}
	if (somethingChanged) {
	if (useUniCharPtr)
	result = (NSString *)CFStringCreateWithCharactersNoCopy(NULL, uniCharPtr, len, NULL);
	else
	result = (NSString *)CFStringCreateWithCStringNoCopy(NULL, charPtr, kCFStringEncodingISOLatin1, NULL);
	} else
	result = [self retain];

	return [result autorelease];
	}

	@end

	@implementation NSData (WebKitExtras)

	- (NSString *)_webkit_guessedMIMETypeForXML
	{
	NSUInteger length = [self length];
	const UInt8* bytes = static_cast<const UInt8*>([self bytes]);

	#define CHANNEL_TAG_LENGTH 7

	const char* p = reinterpret_cast<const char*>(bytes);
	int remaining = std::min<NSUInteger>(length, WEB_GUESS_MIME_TYPE_PEEK_LENGTH) - (CHANNEL_TAG_LENGTH - 1);

	BOOL foundRDF = false;

	while (remaining > 0) {
	// Look for a "<".
	const char* hit = static_cast<const char*>(memchr(p, '<', remaining));
	if (!hit)
	break;

	// We are trying to identify RSS or Atom. RSS has a top-level
	// element of either <rss> or <rdf>. However, there are
	// non-RSS RDF files, so in the case of <rdf> we further look
	// for a <channel> element. In the case of an Atom file, a
	// top-level <feed> element is all we need to see. Only tags
	// starting with <? or <! can precede the root element. We
	// bail if we don't find an <rss>, <feed> or <rdf> element
	// right after those.

	if (foundRDF) {
	if (!strncasecmp(hit, "<channel", strlen("<channel")))
	return @"application/rss+xml";
	} else if (!strncasecmp(hit, "<rdf", strlen("<rdf")))
	foundRDF = TRUE;
	else if (!strncasecmp(hit, "<rss", strlen("<rss")))
	return @"application/rss+xml";
	else if (!strncasecmp(hit, "<feed", strlen("<feed")))
	return @"application/atom+xml";
	else if (strncasecmp(hit, "<?", strlen("<?")) && strncasecmp(hit, "<!", strlen("<!")))
	return nil;

	// Skip the "<" and continue.
	remaining -= (hit + 1) - p;
	p = hit + 1;
	}

	return nil;
	}

	- (NSString *)_webkit_guessedMIMEType
	{
	#define JPEG_MAGIC_NUMBER_LENGTH 4
	#define SCRIPT_TAG_LENGTH 7
	#define TEXT_HTML_LENGTH 9
	#define VCARD_HEADER_LENGTH 11
	#define VCAL_HEADER_LENGTH 15

	NSString *MIMEType = [self _webkit_guessedMIMETypeForXML];
	if ([MIMEType length])
	return MIMEType;

	NSUInteger length = [self length];
	const char* bytes = static_cast<const char*>([self bytes]);

	const char* p = bytes;
	int remaining = std::min<NSUInteger>(length, WEB_GUESS_MIME_TYPE_PEEK_LENGTH) - (SCRIPT_TAG_LENGTH - 1);
	while (remaining > 0) {
	// Look for a "<".
	const char* hit = static_cast<const char*>(memchr(p, '<', remaining));
	if (!hit)
	break;

	// If we found a "<", look for "<html>" or "<a " or "<script".
	if (!strncasecmp(hit, "<html>", strlen("<html>"))
	\|\| !strncasecmp(hit, "<a ", strlen("<a "))
	\|\| !strncasecmp(hit, "<script", strlen("<script"))
	\|\| !strncasecmp(hit, "<title>", strlen("<title>"))) {
	return @"text/html";
	}

	// Skip the "<" and continue.
	remaining -= (hit + 1) - p;
	p = hit + 1;
	}

	// Test for a broken server which has sent the content type as part of the content.
	// This code could be improved to look for other mime types.
	p = bytes;
	remaining = std::min<NSUInteger>(length, WEB_GUESS_MIME_TYPE_PEEK_LENGTH) - (TEXT_HTML_LENGTH - 1);
	while (remaining > 0) {
	// Look for a "t" or "T".
	const char* hit = nullptr;
	const char* lowerhit = static_cast<const char*>(memchr(p, 't', remaining));
	const char* upperhit = static_cast<const char*>(memchr(p, 'T', remaining));
	if (!lowerhit && !upperhit)
	break;

	if (!lowerhit)
	hit = upperhit;
	else if (!upperhit)
	hit = lowerhit;
	else
	hit = std::min<const char*>(lowerhit, upperhit);

	// If we found a "t/T", look for "text/html".
	if (!strncasecmp(hit, "text/html", TEXT_HTML_LENGTH))
	return @"text/html";

	// Skip the "t/T" and continue.
	remaining -= (hit + 1) - p;
	p = hit + 1;
	}

	if ((length >= VCARD_HEADER_LENGTH) && !strncmp(bytes, "BEGIN:VCARD", VCARD_HEADER_LENGTH))
	return @"text/vcard";
	if ((length >= VCAL_HEADER_LENGTH) && !strncmp(bytes, "BEGIN:VCALENDAR", VCAL_HEADER_LENGTH))
	return @"text/calendar";

	// Test for plain text.
	NSUInteger i;
	for (i = 0; i < length; ++i) {
	char c = bytes[i];
	if ((c < 0x20 \|\| c > 0x7E) && (c != '\t' && c != '\r' && c != '\n'))
	break;
	}
	if (i == length) {
	// Didn't encounter any bad characters, looks like plain text.
	return @"text/plain";
	}

	// Looks like this is a binary file.

	// Sniff for the JPEG magic number.
	if ((length >= JPEG_MAGIC_NUMBER_LENGTH) && !strncmp(bytes, "\xFF\xD8\xFF\xE0", JPEG_MAGIC_NUMBER_LENGTH))
	return @"image/jpeg";

	#undef JPEG_MAGIC_NUMBER_LENGTH
	#undef SCRIPT_TAG_LENGTH
	#undef TEXT_HTML_LENGTH
	#undef VCARD_HEADER_LENGTH
	#undef VCAL_HEADER_LENGTH

	return nil;
	}

	@end

	@implementation NSData (WebNSDataExtras)

	- (BOOL)_web_isCaseInsensitiveEqualToCString:(const char *)string
	{
	ASSERT(string);

	const char* bytes = static_cast<const char*>([self bytes]);
	return !strncasecmp(bytes, string, [self length]);
	}

	static const UInt8 _findEOL(const UInt8 bytes, CFIndex len)
	{
	// According to the HTTP specification EOL is defined as
	// a CRLF pair. Unfortunately, some servers will use LF
	// instead. Worse yet, some servers will use a combination
	// of both (e.g. <header>CRLFLF<body>), so findEOL needs
	// to be more forgiving. It will now accept CRLF, LF, or
	// CR.
	//
	// It returns NULL if EOL is not found or it will return
	// a pointer to the first terminating character.
	for (CFIndex i = 0; i < len; i++) {
	UInt8 c = bytes[i];
	if ('\n' == c)
	return bytes + i;
	if ('\r' == c) {
	// Check to see if spanning buffer bounds
	// (CRLF is across reads). If so, wait for
	// next read.
	if (i + 1 == len)
	break;

	return bytes + i;
	}
	}

	return nullptr;
	}

	- (NSMutableDictionary *)_webkit_parseRFC822HeaderFields
	{
	NSMutableDictionary *headerFields = [NSMutableDictionary dictionary];

	const UInt8* bytes = static_cast<const UInt8*>([self bytes]);
	NSUInteger length = [self length];
	NSString *lastKey = nil;
	const UInt8 *eol;

	// Loop over lines until we're past the header, or we can't find any more end-of-lines
	while ((eol = _findEOL(bytes, length))) {
	const UInt8 *line = bytes;
	SInt32 lineLength = eol - bytes;

	// Move bytes to the character after the terminator as returned by _findEOL.
	bytes = eol + 1;
	if (('\r' == eol) && ('\n' == bytes))
	bytes++; // Safe since _findEOL won't return a spanning CRLF.

	length -= (bytes - line);
	if (!lineLength) {
	// Blank line; we're at the end of the header
	break;
	}
	if (line == ' ' \|\| line == '\t') {
	// Continuation of the previous header
	if (!lastKey) {
	// malformed header; ignore it and continue
	continue;
	}
	// Merge the continuation of the previous header
	NSString *currentValue = [headerFields objectForKey:lastKey];
	NSString newValue = (NSString )CFStringCreateWithBytes(NULL, line, lineLength, kCFStringEncodingISOLatin1, FALSE);
	ASSERT(currentValue);
	ASSERT(newValue);
	NSString *mergedValue = [[NSString alloc] initWithFormat:@"%@%@", currentValue, newValue];
	[headerFields setObject:(NSString *)mergedValue forKey:lastKey];
	[newValue release];
	[mergedValue release];
	// Note: currentValue is autoreleased
	} else {
	// Brand new header
	const UInt8 *colon;
	for (colon = line; *colon != ':' && colon != eol; colon++) { }
	if (colon == eol) {
	// malformed header; ignore it and continue
	continue;
	}
	lastKey = (NSString *)CFStringCreateWithBytes(NULL, line, colon - line, kCFStringEncodingISOLatin1, FALSE);
	[lastKey autorelease];
	NSString *value = [lastKey _web_capitalizeRFC822HeaderFieldName];
	lastKey = value;
	for (colon++; colon != eol; colon++) {
	if (colon != ' ' && colon != '\t')
	break;
	}
	if (colon == eol) {
	value = [[NSString alloc] initWithString:@""];
	[value autorelease];
	} else {
	value = (NSString *)CFStringCreateWithBytes(NULL, colon, eol-colon, kCFStringEncodingISOLatin1, FALSE);
	[value autorelease];
	}
	NSString *oldValue = [headerFields objectForKey:lastKey];
	if (oldValue) {
	NSString *newValue = [[NSString alloc] initWithFormat:@"%@, %@", oldValue, value];
	value = newValue;
	[newValue autorelease];
	}
	[headerFields setObject:(NSString *)value forKey:lastKey];
	}
	}

	return headerFields;
	}

	- (BOOL)_web_startsWithBlankLine
	{
	return [self length] > 0 && ((const char *)[self bytes])[0] == '\n';
	}

	- (NSInteger)_web_locationAfterFirstBlankLine
	{
	const char bytes = (const char )[self bytes];
	NSUInteger length = [self length];

	unsigned i;
	for (i = 0; i < length - 4; i++) {

	// Support for Acrobat. It sends "\n\n".
	if (bytes[i] == '\n' && bytes[i+1] == '\n')
	return i+2;

	// Returns the position after 2 CRLF's or 1 CRLF if it is the first line.
	if (bytes[i] == '\r' && bytes[i+1] == '\n') {
	i += 2;
	if (i == 2)
	return i;
	if (bytes[i] == '\n') {
	// Support for Director. It sends "\r\n\n" (3880387).
	return i+1;
	}
	if (bytes[i] == '\r' && bytes[i+1] == '\n') {
	// Support for Flash. It sends "\r\n\r\n" (3758113).
	return i+2;
	}
	}
	}
	return NSNotFound;
	}

	@end