/// <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(); } } }