public static void Download(string uri, string localPath, DownloadProgressDelegate progressDelegate)
{
long remoteSize;
string fullLocalPath; // Full local path including file name if only directory was provided.
try
{
/// Get the name of the remote file.
Uri remoteUri = new Uri(uri);
string fileName = Path.GetFileName(remoteUri.LocalPath);
if (Path.GetFileName(localPath).Length == 0)
{
fullLocalPath = Path.Combine(localPath, fileName);
}
else
{
fullLocalPath = localPath;
}
/// Have to get size of remote object through the webrequest as not available on remote files,
/// although it does work on local files.
using (WebResponse response = WebRequest.Create(uri).GetResponse())
using (Stream stream = response.GetResponseStream())
remoteSize = response.ContentLength;
}
catch (Exception ex)
{
throw new ApplicationException(string.Format("Error connecting to URI (Exception={0})", ex.Message), ex);
}
int bytesRead = 0, bytesReadTotal = 0;
try
{
using (WebClient client = new WebClient())
using (Stream streamRemote = client.OpenRead(new Uri(uri)))
using (Stream streamLocal = new FileStream(fullLocalPath, FileMode.Create, FileAccess.Write, FileShare.None))
{
byte[] byteBuffer = new byte[1024 * 1024 * 2]; // 2 meg buffer although in testing only got to 10k max usage.
int perc = 0;
while ((bytesRead = streamRemote.Read(byteBuffer, 0, byteBuffer.Length)) > 0)
{
bytesReadTotal += bytesRead;
streamLocal.Write(byteBuffer, 0, bytesRead);
int newPerc = (int)((double)bytesReadTotal / (double)remoteSize * 100);
if (newPerc > perc)
{
perc = newPerc;
progressDelegate?.Invoke(perc, bytesReadTotal, (int)remoteSize);
}
}
}
}
catch (Exception ex)
{
throw new ApplicationException(string.Format("Error downloading file (Exception={0})", ex.Message), ex);
}
}
/// <summary>
/// Asynchronously downloads and assembles a multi-part file as specified by a <see cref="Neon.Deployment.DownloadManifest"/>.
/// </summary>
/// <param name="manifest">The download details.</param>
/// <param name="targetPath">The target file path.</param>
/// <param name="progressAction">Optionally specifies an action to be called with the the percentage downloaded.</param>
/// <param name="partTimeout">Optionally specifies the HTTP download timeout for each part (defaults to 10 minutes).</param>
/// <param name="retry">Optionally specifies the retry policy. This defaults to a reasonable policy.</param>
/// <param name="cancellationToken">Optionally specifies the operation cancellation token.</param>
/// <returns>The path to the downloaded file.</returns>
/// <exception cref="IOException">Thrown when the download is corrupt.</exception>
/// <exception cref="SocketException">Thrown for network errors.</exception>
/// <exception cref="HttpException">Thrown for HTTP network errors.</exception>
/// <exception cref="OperationCanceledException">Thrown when the operation was cancelled.</exception>
/// <remarks>
/// <para>
/// This method downloads the file specified by <paramref name="manifest"/> to the folder specified, creating
/// the folder first when required. The file will be downloaded in parts, where each part will be validated
/// by comparing the part's MD5 hash (when present) with the computed value. The output file will be named
/// <see cref="DownloadManifest.Name"/> and the overall MD5 hash will also be saved using the same file name but
/// <b>adding</b> the <b>.md5</b> extension.
/// </para>
/// <para>
/// This method will continue downloading a partially downloaded file. This works by validating the already
/// downloaded parts against their MD5 hashes and then continuing part downloads after the last valid part.
/// Nothing will be downloaded when the existing file is fully formed.
/// </para>
/// <note>
/// The target files (output and MD5) will be deleted when download appears to be corrupt.
/// </note>
/// </remarks>
public static async Task <string> DownloadMultiPartAsync(
DownloadManifest manifest,
string targetPath,
DownloadProgressDelegate progressAction = null,
TimeSpan partTimeout = default,
IRetryPolicy retry = null,
CancellationToken cancellationToken = default)
{
await SyncContext.Clear;
Covenant.Requires <ArgumentNullException>(manifest != null, nameof(manifest));
Covenant.Requires <ArgumentNullException>(!string.IsNullOrEmpty(targetPath), nameof(targetPath));
retry = retry ?? new ExponentialRetryPolicy(TransientDetector.NetworkOrHttp, maxAttempts: 5);
if (partTimeout <= TimeSpan.Zero)
{
partTimeout = TimeSpan.FromMinutes(10);
}
var targetFolder = Path.GetDirectoryName(targetPath);
Directory.CreateDirectory(targetFolder);
var targetMd5Path = Path.Combine(Path.GetDirectoryName(targetPath), Path.GetFileName(targetPath) + ".md5");
var nextPartNumber = 0;
// If the target file already exists along with its MD5 hash file:
//
// 1. Compare the manifest MD5 with the local MD5 hash file and
// quickly continue with the download when these don't match.
//
// 2. When the MD5 files match, compute the MD5 of the downloaded
// file and compare that with the manifest and continue with
// the download when these don't match.
if (File.Exists(targetPath) && File.Exists(targetMd5Path) && File.ReadAllText(targetMd5Path).Trim() == manifest.Md5)
{
if (File.ReadAllText(targetMd5Path).Trim() == manifest.Md5)
{
using (var downloadStream = File.OpenRead(targetPath))
{
if (CryptoHelper.ComputeMD5String(downloadStream) == manifest.Md5)
{
return(targetPath);
}
}
}
}
NeonHelper.DeleteFile(targetMd5Path); // We'll recompute this below
// Validate the parts of any existing target file to determine where
// to start downloading missing parts.
if (File.Exists(targetPath))
{
using (var output = new FileStream(targetPath, System.IO.FileMode.Open, FileAccess.ReadWrite))
{
var pos = 0L;
foreach (var part in manifest.Parts.OrderBy(part => part.Number))
{
progressAction?.Invoke(DownloadProgressType.Check, (int)((double)pos / (double)manifest.Size * 100.0));
// Handle a partially downloaded part. We're going to truncate the file to
// remove the partial part and then break to start re-downloading the part.
if (output.Length < pos + part.Size)
{
output.SetLength(pos);
nextPartNumber = part.Number;
break;
}
// Validate the part MD5. We're going to truncate the file to remove the
// partial part and then break to start re-downloading the part.
using (var partStream = new SubStream(output, pos, part.Size))
{
if (CryptoHelper.ComputeMD5String(partStream) != part.Md5)
{
output.SetLength(pos);
nextPartNumber = part.Number;
break;
}
}
pos += part.Size;
nextPartNumber = part.Number + 1;
}
}
}
// Download any remaining parts.
if (progressAction != null && !progressAction.Invoke(DownloadProgressType.Download, 0))
{
return(targetPath);
}
if (nextPartNumber == manifest.Parts.Count)
{
progressAction?.Invoke(DownloadProgressType.Download, 100);
return(targetPath);
}
try
{
using (var httpClient = new HttpClient())
{
httpClient.Timeout = partTimeout;
using (var output = new FileStream(targetPath, System.IO.FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
// Determine the starting position of the next part to be downloaded.
var pos = manifest.Parts
.Where(part => part.Number < nextPartNumber)
.Sum(part => part.Size);
// Download the remaining parts.
foreach (var part in manifest.Parts
.Where(part => part.Number >= nextPartNumber)
.OrderBy(part => part.Number))
{
await retry.InvokeAsync(
async() =>
{
output.Position = pos;
var response = await httpClient.GetAsync(part.Uri, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
response.EnsureSuccessStatusCode();
using (var contentStream = await response.Content.ReadAsStreamAsync())
{
await contentStream.CopyToAsync(output, cancellationToken);
}
});
// Ensure that the downloaded part size matches the specification.
if (output.Position - pos != part.Size)
{
throw new IOException($"[{manifest.Name}]: Part [{part.Number}] actual size [{output.Position - pos}] does not match the expected size [{part.Size}].");
}
// Ensure that the downloaded part MD5 matches the specification.
using (var subStream = new SubStream(output, pos, part.Size))
{
var actualMd5 = CryptoHelper.ComputeMD5String(subStream);
if (actualMd5 != part.Md5)
{
throw new IOException($"[{manifest.Name}]: Part [{part.Number}] actual MD5 [{actualMd5}] does not match the expected MD5 [{part.Md5}].");
}
}
pos += part.Size;
if (progressAction != null && !progressAction.Invoke(DownloadProgressType.Download, (int)(100.0 * ((double)part.Number / (double)manifest.Parts.Count))))
{
return(targetPath);
}
}
if (output.Length != manifest.Size)
{
throw new IOException($"[{manifest.Name}]: Expected size [{manifest.Size}] got [{output.Length}].");
}
}
progressAction?.Invoke(DownloadProgressType.Download, 100);
File.WriteAllText(targetMd5Path, manifest.Md5, Encoding.ASCII);
return(targetPath);
}
}
catch (IOException)
{
NeonHelper.DeleteFile(targetPath);
NeonHelper.DeleteFile(targetMd5Path);
throw;
}
}
