/// <summary>
/// Test a 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 <see cref="HeaderTest">tests</see> 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 compressedSize = ReadLEUint();
long size = ReadLEUint();
int storedNameLength = ReadLEUshort();
int extraDataLength = ReadLEUshort();
byte[] nameData = new byte[storedNameLength];
StreamUtils.ReadFully(baseStream_, nameData);
byte[] extraData = new byte[extraDataLength];
StreamUtils.ReadFully(baseStream_, extraData);
ZipExtraData localExtraData = new ZipExtraData(extraData);
// Extra data / zip64 checks
if (localExtraData.Find(1))
{
// TODO Check for tag values being distinct.. Multiple zip64 tags means what?
// Zip64 extra data but 'extract version' is 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 = localExtraData.ReadLong();
compressedSize = localExtraData.ReadLong();
if ((localFlags & (int)GeneralBitFlags.Descriptor) != 0)
{
// These may be valid if patched later
if ( (size != -1) && (size != entry.Size)) {
throw new ZipException("Size invalid for descriptor");
}
if ((compressedSize != -1) && (compressedSize != entry.CompressedSize)) {
throw new ZipException("Compressed size invalid for descriptor");
}
}
}
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");
}
}
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 != 11) &&
(extractVersion != 20) &&
(extractVersion != 21) &&
(extractVersion != 25) &&
(extractVersion != 27) &&
(extractVersion != 45) &&
(extractVersion != 46) &&
(extractVersion != 50) &&
(extractVersion != 51) &&
(extractVersion != 52) &&
(extractVersion != 61) &&
(extractVersion != 62) &&
(extractVersion != 63)
)
{
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.ReservedPKware4 | GeneralBitFlags.ReservedPkware14 | GeneralBitFlags.ReservedPkware15)) != 0)
{
throw new ZipException("Reserved bit flags cannot be 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");
}
if (entry.Version != extractVersion)
{
throw new ZipException("Extract version 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.
// This will also apply to streamed entries where size isnt known and the header cant be patched
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");
}
// Name data has already been read convert it and compare.
string localName = ZipConstants.ConvertToStringExt(localFlags, 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 actual size but can have compressed size
if (entry.IsDirectory)
{
if (size > 0)
{
throw new ZipException("Directory cannot have size");
}
// There may be other cases where the compressed size can be greater than this?
// If so until details are known we will be strict.
if (entry.IsCrypted)
{
if (compressedSize > ZipConstants.CryptoHeaderSize + 2)
{
throw new ZipException("Directory compressed size invalid");
}
}
else if (compressedSize > 2)
{
// When not compressed the directory size can validly be 2 bytes
// if the true size wasnt known when data was originally being written.
// NOTE: Versions of the library 0.85.4 and earlier always added 2 bytes
throw new ZipException("Directory compressed size invalid");
}
}
if (!ZipNameTransform.IsValidName(localName, true))
{
throw new ZipException("Name is invalid");
}
}
// Tests that apply to both data and header.
// Size can be verified only if it is known in the local header.
// it will always be known in the central header.
if (((localFlags & (int)GeneralBitFlags.Descriptor) == 0) ||
((size > 0) || (compressedSize > 0))) {
if (size != entry.Size) {
throw new ZipException(
string.Format("Size mismatch between central header({0}) and local header({1})",
entry.Size, size));
}
if (compressedSize != entry.CompressedSize) {
throw new ZipException(
string.Format("Compressed size mismatch between central header({0}) and local header({1})",
entry.CompressedSize, compressedSize));
}
}
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();
}
if ( !localHeader && (offset == uint.MaxValue) ) {
offset = extraData.ReadLong();
}
}
else {
if (
((versionToExtract & 0xff) >= ZipConstants.VersionZip64) &&
((size == uint.MaxValue) || (compressedSize == uint.MaxValue))
) {
throw new ZipException("Zip64 Extended information required but is missing.");
}
}
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();
}
}
}
