/// <summary>
/// Test the local header against that provided from the central directory
/// </summary>
/// <param name="entry">
/// The entry to test against
/// </param>
/// <param name="tests">The type of test to carry out.</param>
/// <returns>The offset of the entries data in the file</returns>
long TestLocalHeader(ZipEntry entry, HeaderTest tests)
{
lock(baseStream_)
{
bool testHeader = (tests & HeaderTest.Header) != 0;
bool testData = (tests & HeaderTest.Extract) != 0;
baseStream_.Seek(offsetOfFirstEntry + entry.Offset, SeekOrigin.Begin);
if ((int)ReadLEUint() != ZipConstants.LocalHeaderSignature) {
throw new ZipException(string.Format("Wrong local header signature @{0:X}", offsetOfFirstEntry + entry.Offset));
}
short extractVersion = ( short )ReadLEUshort();
short localFlags = ( short )ReadLEUshort();
short compressionMethod = ( short )ReadLEUshort();
short fileTime = ( short )ReadLEUshort();
short fileDate = ( short )ReadLEUshort();
uint crcValue = ReadLEUint();
long size = ReadLEUint();
long compressedSize = ReadLEUint();
int storedNameLength = ReadLEUshort();
int extraDataLength = ReadLEUshort();
if ( testData ) {
if ( entry.IsFile ) {
if ( !entry.IsCompressionMethodSupported() ) {
throw new ZipException("Compression method not supported");
}
if ( (extractVersion > ZipConstants.VersionMadeBy)
|| ((extractVersion > 20) && (extractVersion < ZipConstants.VersionZip64)) ) {
throw new ZipException(string.Format("Version required to extract this entry not supported ({0})", extractVersion));
}
if ( (localFlags & ( int )(GeneralBitFlags.Patched | GeneralBitFlags.StrongEncryption | GeneralBitFlags.EnhancedCompress | GeneralBitFlags.HeaderMasked)) != 0 ) {
throw new ZipException("The library does not support the zip version required to extract this entry");
}
}
}
if ( testHeader ) {
if ((extractVersion < 63) && // Ignore later versions as we dont know about them..
(extractVersion != 10) &&
(extractVersion != 20) &&
(extractVersion != 21) &&
(extractVersion != 25) &&
(extractVersion != 27) &&
(extractVersion != 45) &&
(extractVersion != 46) &&
(extractVersion != 50) &&
(extractVersion != 51) &&
(extractVersion != 61) &&
(extractVersion != 62)
) {
throw new ZipException(string.Format("Version required to extract this entry is invalid ({0})", extractVersion));
}
// Local entry flags dont have reserved bit set on.
if ( (localFlags & ( int )GeneralBitFlags.Reserved) != 0 ) {
throw new ZipException("Reserved bit flag cannot bet set.");
}
// Encryption requires extract version >= 20
if ( ((localFlags & ( int )GeneralBitFlags.Encrypted) != 0) && (extractVersion < 20) ) {
throw new ZipException(string.Format("Version required to extract this entry is too low for encryption ({0})", extractVersion));
}
// Strong encryption requires encryption flag to be set and extract version >= 50.
if ( (localFlags & (int)GeneralBitFlags.StrongEncryption) != 0 ) {
if ( (localFlags & (int)GeneralBitFlags.Encrypted) == 0 ) {
throw new ZipException("Strong encryption flag set but encryption flag is not set");
}
if ( extractVersion < 50 ) {
throw new ZipException(string.Format("Version required to extract this entry is too low for encryption ({0})", extractVersion));
}
}
// Patched entries require extract version >= 27
if ( ((localFlags & ( int )GeneralBitFlags.Patched) != 0) && (extractVersion < 27) ) {
throw new ZipException(string.Format("Patched data requires higher version than ({0})", extractVersion));
}
// Central header flags match local entry flags.
if ( localFlags != entry.Flags ) {
throw new ZipException("Central header/local header flags mismatch");
}
// Central header compression method matches local entry
if ( entry.CompressionMethod != ( CompressionMethod )compressionMethod ) {
throw new ZipException("Central header/local header compression method mismatch");
}
// Strong encryption and extract version match
if ( (localFlags & ( int )GeneralBitFlags.StrongEncryption) != 0 ) {
if ( extractVersion < 62 ) {
throw new ZipException("Strong encryption flag set but version not high enough");
}
}
if ( (localFlags & ( int )GeneralBitFlags.HeaderMasked) != 0 ) {
if ( (fileTime != 0) || (fileDate != 0) ) {
throw new ZipException("Header masked set but date/time values non-zero");
}
}
if ( (localFlags & ( int )GeneralBitFlags.Descriptor) == 0 ) {
if ( crcValue != (uint)entry.Crc ) {
throw new ZipException("Central header/local header crc mismatch");
}
}
// Crc valid for empty entry.
if ( (size == 0) && (compressedSize == 0) ) {
if ( crcValue != 0 ) {
throw new ZipException("Invalid CRC for empty entry");
}
}
// TODO: make test more correct... can't compare lengths as was done originally as this can fail for MBCS strings
// Assuming a code page at this point is not valid? Best is to store the name length in the ZipEntry probably
if ( entry.Name.Length > storedNameLength ) {
throw new ZipException("File name length mismatch");
}
byte[] nameData = new byte[storedNameLength];
StreamUtils.ReadFully(baseStream_, nameData);
string localName = ZipConstants.ConvertToString(nameData);
// Central directory and local entry name match
if ( localName != entry.Name ) {
throw new ZipException("Central header and local header file name mismatch");
}
// Directories have zero size.
if ( entry.IsDirectory ) {
if ( (compressedSize != 0) || (size != 0) ) {
throw new ZipException("Directory cannot have size");
}
}
if ( !ZipNameTransform.IsValidName(localName, true) ) {
throw new ZipException("Name is invalid");
}
byte[] data = new byte[extraDataLength];
StreamUtils.ReadFully(baseStream_, data);
ZipExtraData ed = new ZipExtraData(data);
// Extra data / zip64 checks
if ( ed.Find(1) ) {
// Zip64 extra data but extract version too low
if ( extractVersion < ZipConstants.VersionZip64 ) {
throw new ZipException(
string.Format("Extra data contains Zip64 information but version {0}.{1} is not high enough",
extractVersion / 10, extractVersion % 10));
}
// Zip64 extra data but size fields dont indicate its required.
if ( (( uint )size != uint.MaxValue) && (( uint )compressedSize != uint.MaxValue) ) {
throw new ZipException("Entry sizes not correct for Zip64");
}
size = ed.ReadLong();
compressedSize = ed.ReadLong();
}
else {
// No zip64 extra data but entry requires it.
if ( (extractVersion >= ZipConstants.VersionZip64) &&
((( uint )size == uint.MaxValue) || (( uint )compressedSize == uint.MaxValue)) ) {
throw new ZipException("Required Zip64 extended information missing");
}
}
}
int extraLength = storedNameLength + extraDataLength;
return offsetOfFirstEntry + entry.Offset + ZipConstants.LocalHeaderBaseSize + extraLength;
}
}
/// <summary>
/// Process extra data fields updating the entry based on the contents.
/// </summary>
/// <param name="localHeader">True if the extra data fields should be handled
/// for a local header, rather than for a central header.
/// </param>
internal void ProcessExtraData(bool localHeader)
{
ZipExtraData extraData = new ZipExtraData(this.extra);
if (extraData.Find(0x0001))
{
if ((versionToExtract & 0xff) < ZipConstants.VersionZip64)
{
throw new ZipException("Zip64 Extended information found but version is not valid");
}
// The recorded size will change but remember that this is zip64.
forceZip64_ = true;
if (extraData.ValueLength < 4)
{
throw new ZipException("Extra data extended Zip64 information length is invalid");
}
if (localHeader || (size == uint.MaxValue))
{
size = (ulong)extraData.ReadLong();
}
if (localHeader || (compressedSize == uint.MaxValue))
{
compressedSize = (ulong)extraData.ReadLong();
}
}
else
{
if (
((versionToExtract & 0xff) >= ZipConstants.VersionZip64) &&
((size == uint.MaxValue) ||
(compressedSize == uint.MaxValue)))
{
throw new ZipException("Zip64 Extended information required but is missing.");
}
}
/* TODO: Testing for handling of windows extra data
* if ( extraData.Find(10) ) {
* // No room for any tags.
* if ( extraData.ValueLength < 8 ) {
* throw new ZipException("NTFS Extra data invalid");
* }
*
* extraData.ReadInt(); // Reserved
*
* while ( extraData.UnreadCount >= 4 ) {
* int ntfsTag = extraData.ReadShort();
* int ntfsLength = extraData.ReadShort();
* if ( ntfsTag == 1 ) {
* if ( ntfsLength >= 24 ) {
* long lastModification = extraData.ReadLong();
* long lastAccess = extraData.ReadLong();
* long createTime = extraData.ReadLong();
*
* DateTime = System.DateTime.FromFileTime(lastModification);
* }
* break;
* }
* else {
* // An unknown NTFS tag so simply skip it.
* extraData.Skip(ntfsLength);
* }
* }
* }
* else
*/
if (extraData.Find(0x5455))
{
int length = extraData.ValueLength;
int flags = extraData.ReadByte();
// Can include other times but these are ignored. Length of data should
// actually be 1 + 4 * no of bits in flags.
if (((flags & 1) != 0) && (length >= 5))
{
int iTime = extraData.ReadInt();
DateTime = (new System.DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime() +
new TimeSpan(0, 0, 0, iTime, 0)).ToLocalTime();
}
}
}
/// <summary>
/// Process extra data fields updating the entry based on the contents.
/// </summary>
/// <param name="localHeader">True if the extra data fields should be handled
/// for a local header, rather than for a central header.
/// </param>
internal void ProcessExtraData(bool localHeader)
{
ZipExtraData extraData = new ZipExtraData(this.extra);
if ( extraData.Find(0x0001) ) {
if ( (versionToExtract & 0xff) < ZipConstants.VersionZip64 ) {
throw new ZipException("Zip64 Extended information found but version is not valid");
}
// The recorded size will change but remember that this is zip64.
forceZip64_ = true;
if ( extraData.ValueLength < 4 ) {
throw new ZipException("Extra data extended Zip64 information length is invalid");
}
if ( localHeader || (size == uint.MaxValue) ) {
size = (ulong)extraData.ReadLong();
}
if ( localHeader || (compressedSize == uint.MaxValue) ) {
compressedSize = (ulong)extraData.ReadLong();
}
}
else {
if (
((versionToExtract & 0xff) >= ZipConstants.VersionZip64) &&
( (size == uint.MaxValue) ||
(compressedSize == uint.MaxValue) )) {
throw new ZipException("Zip64 Extended information required but is missing.");
}
}
/* TODO: Testing for handling of windows extra data
if ( extraData.Find(10) ) {
// No room for any tags.
if ( extraData.ValueLength < 8 ) {
throw new ZipException("NTFS Extra data invalid");
}
extraData.ReadInt(); // Reserved
while ( extraData.UnreadCount >= 4 ) {
int ntfsTag = extraData.ReadShort();
int ntfsLength = extraData.ReadShort();
if ( ntfsTag == 1 ) {
if ( ntfsLength >= 24 ) {
long lastModification = extraData.ReadLong();
long lastAccess = extraData.ReadLong();
long createTime = extraData.ReadLong();
DateTime = System.DateTime.FromFileTime(lastModification);
}
break;
}
else {
// An unknown NTFS tag so simply skip it.
extraData.Skip(ntfsLength);
}
}
}
else
*/
if ( extraData.Find(0x5455) ) {
int length = extraData.ValueLength;
int flags = extraData.ReadByte();
// Can include other times but these are ignored. Length of data should
// actually be 1 + 4 * no of bits in flags.
if ( ((flags & 1) != 0) && (length >= 5) ) {
int iTime = extraData.ReadInt();
DateTime = (new System.DateTime ( 1970, 1, 1, 0, 0, 0 ).ToUniversalTime() +
new TimeSpan ( 0, 0, 0, iTime, 0 )).ToLocalTime();
}
}
}
