Skip to content

Commit

Permalink
Don't stream blob directly anymore. Uses SAS for downloading from blo…
Browse files Browse the repository at this point in the history 
…b storage now.
  • Loading branch information
@vnbaaij
vnbaaij committed Aug 9, 2018
1 parent 750042c commit 0f04c8c
Show file tree
Hide file tree
Showing 3 changed files with 183 additions and 32 deletions.
2 changes: 1 addition & 1 deletion samples/AlloySampleAzure/Views/Shared/Blocks/TeaserBlock.cshtml
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@
<p @Html.EditAttributes(x => x.Text)>@Model.Text</p>
<div @Html.EditAttributes(x => x.Image)>

@Html.Picture(Html.ProcessImage(Model.Image).Resize(378, null).ReplaceColor("fff", "f00", 99).Watermark("Episerver", new Point(100, 100), "fff"), ImageTypes.Teaser)
@Html.Picture(Html.ProcessImage(Model.Image).Resize(378, null).ReplaceColor("fff", "f00", 99).Watermark("Episerver", new Point(100, 100), "fff"), ImageTypes.Teaser, lazyLoad: false)

</div>
}
Expand Down
209 changes: 180 additions & 29 deletions src/ImageProcessor.Web.Episerver.Azure/AzureBlobCache.cs
View file
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Net;
Expand Down Expand Up @@ -292,52 +293,202 @@ private async Task<bool> IsUpdatedAsync(DateTime creationDate)
/// </param>
public override void RewritePath(HttpContext context)
{
//context.RewritePath(CachedPath, false);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(CachedPath);

CloudBlockBlob blockBlob = rootContainer.GetBlockBlobReference(blobPath);
string p = GetSaSForBlob(blockBlob, SharedAccessBlobPermissions.Read);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(p);

// Redirect the request to the blob URL
request.Method = "HEAD";
request.Timeout = timeout;

HttpWebResponse response;
try
{
response = (HttpWebResponse)request.GetResponse();
response.Dispose();
ImageProcessingModule.AddCorsRequestHeaders(context);
context.Response.Redirect(CachedPath, false);
}
catch (WebException ex)
{
response = (HttpWebResponse)ex.Response;
//if (true)
//{
// Map headers to enable 304s to pass through
if (context.Request.Headers["If-Modified-Since"] != null)
{
TrySetIfModifiedSinceDate(context, request);
}

if (response != null)
string[] mapRequestHeaders = { "Cache-Control", "If-None-Match" };
foreach (string h in mapRequestHeaders)
{
HttpStatusCode responseCode = response.StatusCode;
if (context.Request.Headers[h] != null)
{
request.Headers.Add(h, context.Request.Headers[h]);
}
}

// A 304 (NotModified) is not an error
// Write the blob storage directly to the stream
request.Method = "GET";
request.Timeout = timeout;

HttpWebResponse response = null;
try
{
response = (HttpWebResponse)request.GetResponse();
}
catch (WebException ex)
{
// A 304 is not an error
// It appears that some CDN's on Azure (Akamai) do not work properly when making head requests.
// They will return a response url and other headers but a 500 status code.
if (responseCode == HttpStatusCode.NotModified || response.ResponseUri.AbsoluteUri.Equals(CachedPath, StringComparison.OrdinalIgnoreCase))
if (ex.Response != null && (((HttpWebResponse)ex.Response).StatusCode == HttpStatusCode.NotModified
|| ex.Response.ResponseUri.AbsoluteUri.Equals(CachedPath, StringComparison.OrdinalIgnoreCase)))
{
response.Dispose();
ImageProcessingModule.AddCorsRequestHeaders(context);
context.Response.Redirect(CachedPath, false);
response = (HttpWebResponse)ex.Response;
}
else
{
response.Dispose();
logger.Error("Unable to rewrite cached path to: " + CachedPath);
response?.Dispose();
logger.Error("Unable to stream cached path: " + CachedPath);
return;
}
}

Stream cachedStream = response.GetResponseStream();

if (cachedStream != null)
{
HttpResponse contextResponse = context.Response;

// If streaming but not using a CDN the headers will be null.
// See https://github.com/JimBobSquarePants/ImageProcessor/pull/466
string etagHeader = response.Headers["ETag"];
if (!string.IsNullOrWhiteSpace(etagHeader))
{
contextResponse.Headers.Add("ETag", etagHeader);
}

string lastModifiedHeader = response.Headers["Last-Modified"];
if (!string.IsNullOrWhiteSpace(lastModifiedHeader))
{
contextResponse.Headers.Add("Last-Modified", lastModifiedHeader);
}

cachedStream.CopyTo(contextResponse.OutputStream); // Will be empty on 304s
ImageProcessingModule.SetHeaders(
context,
response.StatusCode == HttpStatusCode.NotModified ? null : response.ContentType,
null,
BrowserMaxDays,
response.StatusCode);
}

cachedStream?.Dispose();
response.Dispose();
//}
//else
//{

// // Redirect the request to the blob URL
// request.Method = "HEAD";
// request.Timeout = timeout;

// HttpWebResponse response;
// try
// {
// response = (HttpWebResponse)request.GetResponse();
// response.Dispose();
// ImageProcessingModule.AddCorsRequestHeaders(context);
// context.Response.Redirect(CachedPath, false);
// }
// catch (WebException ex)
// {
// response = (HttpWebResponse)ex.Response;

// if (response != null)
// {
// HttpStatusCode responseCode = response.StatusCode;

// // A 304 (NotModified) is not an error
// // It appears that some CDN's on Azure (Akamai) do not work properly when making head requests.
// // They will return a response url and other headers but a 500 status code.
// if (responseCode == HttpStatusCode.NotModified || response.ResponseUri.AbsoluteUri.Equals(CachedPath, StringComparison.OrdinalIgnoreCase))
// {
// response.Dispose();
// ImageProcessingModule.AddCorsRequestHeaders(context);
// context.Response.Redirect(CachedPath, false);
// }
// else
// {
// response.Dispose();
// logger.Error("Unable to rewrite cached path to: " + CachedPath);
// }
// }
// else
// {
// // It's a 404, we should redirect to the cached path we have just saved to.
// ImageProcessingModule.AddCorsRequestHeaders(context);
// context.Response.Redirect(CachedPath, false);
// }
// }
//}
}


/// <summary>
/// Tries to set IfModifiedSince header however this crashes when context.Request.Headers["If-Modified-Since"] exists,
/// but cannot be parsed. It cannot be parsed when it comes from Google Bot as UTC <example>Sun, 27 Nov 2016 20:01:45 UTC</example>
/// so DateTime.TryParse. If it returns false, then log the error.
/// </summary>
/// <param name="context">The current context</param>
/// <param name="request">The current request</param>
private static void TrySetIfModifiedSinceDate(HttpContext context, HttpWebRequest request)
{

string ifModifiedFromRequest = context.Request.Headers["If-Modified-Since"];

if (DateTime.TryParse(ifModifiedFromRequest, out DateTime ifModifiedDate))
{
request.IfModifiedSince = ifModifiedDate;
}
else
{
if (ifModifiedFromRequest.ToLower().Contains("utc"))
{
ifModifiedFromRequest = ifModifiedFromRequest.ToLower().Replace("utc", string.Empty);

if (DateTime.TryParse(ifModifiedFromRequest, out ifModifiedDate))
{
request.IfModifiedSince = ifModifiedDate;
}
}
else
{
// It's a 404, we should redirect to the cached path we have just saved to.
ImageProcessingModule.AddCorsRequestHeaders(context);
context.Response.Redirect(CachedPath, false);
logger.Error($"Unable to parse date {context.Request.Headers["If-Modified-Since"]} for {context.Request.Url}");
}
}
}

/// <summary>
/// Creates a SAS URI for the blob container.
/// </summary>
/// <param name="blobContainer"></param>
/// <param name="permission"></param>
/// <returns></returns>
static string GetSaSForBlobContainer(CloudBlobContainer blobContainer, SharedAccessBlobPermissions permission)
{
var sas = blobContainer.GetSharedAccessSignature(new SharedAccessBlobPolicy()
{
Permissions = permission,
SharedAccessStartTime = DateTime.UtcNow.AddMinutes(-5),//SAS Start time is back by 5 minutes to take clock skewness into consideration
SharedAccessExpiryTime = DateTime.UtcNow.AddMinutes(15),
});
return string.Format(CultureInfo.InvariantCulture, "{0}{1}", blobContainer.Uri, sas);
}

/// <summary>
/// Creates a SAS URI for the blob.
/// </summary>
/// <param name="blob"></param>
/// <param name="permission"></param>
/// <returns></returns>
static string GetSaSForBlob(CloudBlockBlob blob, SharedAccessBlobPermissions permission)
{
var sas = blob.GetSharedAccessSignature(new SharedAccessBlobPolicy()
{
Permissions = permission,
SharedAccessStartTime = DateTime.UtcNow.AddMinutes(-5),
SharedAccessExpiryTime = DateTime.UtcNow.AddMinutes(15),
});
return string.Format(CultureInfo.InvariantCulture, "{0}{1}", blob.Uri, sas);
}
}
}
4 changes: 2 additions & 2 deletions src/ImageProcessor.Web.Episerver.Azure/Properties/AssemblyInfo.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,5 +32,5 @@
// You can specify all the values or you can default the Build and Revision Numbers
// by using the '*' as shown below:
// [assembly: AssemblyVersion("1.0.*")]
[assembly: AssemblyVersion("3.0.0.0")]
[assembly: AssemblyFileVersion("3.0.0.0")]
[assembly: AssemblyVersion("3.0.1.0")]
[assembly: AssemblyFileVersion("3.0.1.0")]

0 comments on commit 0f04c8c

Please sign in to comment.