Ensure external sources for styles only process CSS responses when inlining stylesheets

agrande-ea · martinnormark · commit 574d92d789f0 · 2025-01-06T00:45:56.000+01:00
diff --git a/PreMailer.Net/Benchmarks/Program.cs b/PreMailer.Net/Benchmarks/Program.cs
@@ -1,17 +1,30 @@
 ﻿using AngleSharp;
 using AngleSharp.Html.Parser;
 using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Configs;
+using BenchmarkDotNet.Jobs;
 using BenchmarkDotNet.Running;
+using BenchmarkDotNet.Toolchains.InProcess.NoEmit;
 
 public static class Program
 {
 	public static void Main()
 	{
-		BenchmarkRunner.Run<Realistic>();
+		// Some local environments may run into issues with Windows Defender or 
+		// SentinelOne (and others) when running a benchmark. This ensures we
+		// keep our toolchain within our process and stops the above apps from blocking
+		// our benchmark process, but can slow the execution time.
+		var avSafeConfig = DefaultConfig.Instance
+			.AddJob(
+				Job.ShortRun
+					.WithToolchain(InProcessNoEmitToolchain.Instance)
+					.WithIterationCount(100)
+			);
+
+		BenchmarkRunner.Run<Realistic>(avSafeConfig);
 	}
 }
 
-[SimpleJob(invocationCount: 100, iterationCount: 100)]
 [MemoryDiagnoser]
 public class Realistic
 {
@@ -47,7 +60,7 @@ public void MoveCssInline_AllFlags()
 
 <meta http-equiv=""Content-Type"" content=""text/html; charset=UTF-8"" />
 <title>PreMailer Benchmark</title>
-	
+
 </head>
  
 <body bgcolor=""#123"">
diff --git a/PreMailer.Net/PreMailer.Net/Downloaders/WebDownloader.cs b/PreMailer.Net/PreMailer.Net/Downloaders/WebDownloader.cs
@@ -1,3 +1,4 @@
+using PreMailer.Net.Extensions;
 using System;
 using System.IO;
 using System.Net;
@@ -8,7 +9,7 @@ namespace PreMailer.Net.Downloaders
 	public class WebDownloader : IWebDownloader
 	{
 		private static IWebDownloader _sharedDownloader;
-
+		private const string CssMimeType = "text/css";
 		public static IWebDownloader SharedDownloader
 		{
 			get
@@ -29,8 +30,16 @@ public static IWebDownloader SharedDownloader
 		public string DownloadString(Uri uri)
 		{
 			var request = WebRequest.Create(uri);
+			request.Headers.Add(HttpRequestHeader.Accept, CssMimeType);
+
 			using (var response = request.GetResponse())
 			{
+				// We only support this operation for CSS file/content types coming back
+				// from the response. If we get something different, throw with the unsupported
+				// content type in the message
+				if(response.ParseContentType() != CssMimeType)
+					throw new NotSupportedException($"The Uri type is giving a response in unsupported content type '{response.ContentType}'.");
+
 				switch (response)
 				{
 					case HttpWebResponse httpWebResponse:
diff --git a/PreMailer.Net/PreMailer.Net/Extensions/WebResponseExtensions.cs b/PreMailer.Net/PreMailer.Net/Extensions/WebResponseExtensions.cs
@@ -0,0 +1,24 @@
+﻿using System;
+using System.Net;
+
+namespace PreMailer.Net.Extensions
+{
+	public static class WebResponseExtensions
+	{
+		public static string ParseContentType(this WebResponse response)
+		{
+			if(response == null)
+				throw new NullReferenceException("Malformed response detected when parsing WebResponse Content-Type");
+
+			if(string.IsNullOrEmpty(response.ContentType))
+				throw new NullReferenceException("Malformed Content-Type response detected when parsing WebResponse");
+
+			var results = response.ContentType.Split(';');
+
+			if(results.Length == 0)
+				throw new FormatException("Malformed Content-Type response detected when parsing WebResponse");
+
+			return results[0];
+		}
+	}
+}

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,4 @@`
	`1`	`+using PreMailer.Net.Extensions;`
`1`	`2`	`using System;`
`2`	`3`	`using System.IO;`
`3`	`4`	`using System.Net;`
`@@ -8,7 +9,7 @@ namespace PreMailer.Net.Downloaders`
`8`	`9`	`public class WebDownloader : IWebDownloader`
`9`	`10`	`{`
`10`	`11`	`private static IWebDownloader _sharedDownloader;`
`11`		`-`
	`12`	`+ private const string CssMimeType = "text/css";`
`12`	`13`	`public static IWebDownloader SharedDownloader`
`13`	`14`	`{`
`14`	`15`	`get`
`@@ -29,8 +30,16 @@ public static IWebDownloader SharedDownloader`
`29`	`30`	`public string DownloadString(Uri uri)`
`30`	`31`	`{`
`31`	`32`	`var request = WebRequest.Create(uri);`
	`33`	`+ request.Headers.Add(HttpRequestHeader.Accept, CssMimeType);`
	`34`	`+`
`32`	`35`	`using (var response = request.GetResponse())`
`33`	`36`	`{`
	`37`	`+ // We only support this operation for CSS file/content types coming back`
	`38`	`+ // from the response. If we get something different, throw with the unsupported`
	`39`	`+ // content type in the message`
	`40`	`+ if(response.ParseContentType() != CssMimeType)`
	`41`	`+ throw new NotSupportedException($"The Uri type is giving a response in unsupported content type '{response.ContentType}'.");`
	`42`	`+`
`34`	`43`	`switch (response)`
`35`	`44`	`{`
`36`	`45`	`case HttpWebResponse httpWebResponse:`