private static bool IsAlreadyDownloaded(this IFileRef self, Headers headers, FileEntry targetFile)
{
if (targetFile.Exists)
{
// Cancel download if etag header matches the locally stored one:
if (self.HasMatchingChecksum(headers.GetEtagHeader()))
{
return(true);
}
// Cancel download if local file with the same MD5 hash exists:
var onlineMD5 = headers.GetMD5Checksum();
if (!onlineMD5.IsNullOrEmpty())
{
if (self.HasMatchingChecksum(onlineMD5))
{
return(true);
}
if (onlineMD5 == targetFile.CalcFileMd5Hash())
{
return(true);
}
return(false);
}
/*
* // Cancel download if local file with the exact last-write timestamp exists:
* if (headers.GetRawLastModifiedString() != null) {
* var distance = headers.GetLastModifiedUtcDate(DateTime.MinValue) - targetFile.LastWriteTime.ToUniversalTime();
* Log.d("distance.Milliseconds: " + distance.Milliseconds);
* if (distance.Milliseconds == 0) { return true; }
* }
*/
}
return(false);
}
private static bool CheckMD5AfterDownload(this IFileRef self, Headers headers, FileEntry targetFile)
{
var onlineMD5 = headers.GetMD5Checksum();
if (onlineMD5.IsNullOrEmpty())
{
return(false);
}
string localMD5 = targetFile.CalcFileMd5Hash();
if (localMD5 == onlineMD5)
{
throw new InvalidDataException($"Missmatch in MD5 hashes, local={localMD5} & online={onlineMD5}");
}
self.AddCheckSum(CHECKSUM_MD5, localMD5);
return(true);
}