optimize parse logic and unit tests

Author: tinohager

src/Nager.EmailAuthentication.UnitTest/DkimSignatureParserTests/FoldingTest.cs

@@ -5,6 +5,10 @@ namespace Nager.EmailAuthentication.UnitTest.DkimSignatureParserTests
     [TestClass]
     public sealed class FoldingTest
     {
+        /// <summary>
+        /// DKIM signature folding refers to breaking long header field lines into multiple lines for better readability
+        /// and compliance with email standards. It uses whitespace and line breaks while ensuring the signature remains valid.
+        /// </summary>
         [TestMethod]
         public void TryParse_ValidSelector_ReturnsTrueAndPopulatesDataFragment()
         {

src/Nager.EmailAuthentication.UnitTest/DkimSignatureParserTests/HeaderTest.cs

@@ -0,0 +1,30 @@
+namespace Nager.EmailAuthentication.UnitTest.DkimSignatureParserTests
+{
+    [TestClass]
+    public sealed class HeaderTest
+    {
+        [TestMethod]
+        public void TryParse_NoHeadersDefined_ReturnsTrueAndPopulatesDataFragment()
+        {
+            var dkimSignatureRaw = "v=1; a=rsa-sha256; d=domain.com; s=test; h=; bh=testbodyhash=; b=signaturedata";
+
+            var isSuccessful = DkimSignatureDataFragmentParser.TryParse(dkimSignatureRaw, out var dkimSignatureDataFragment, out var parsingResults);
+
+            Assert.IsTrue(isSuccessful);
+            Assert.IsNotNull(dkimSignatureDataFragment);
+            Assert.IsNotNull(parsingResults, "ParsingResults is null");
+        }
+
+        [TestMethod]
+        public void TryParse_OnlyOneHeaderIsDefined_ReturnsTrueAndPopulatesDataFragment()
+        {
+            var dkimSignatureRaw = "v=1; a=rsa-sha256; d=domain.com; s=test; h=test; bh=testbodyhash=; b=signaturedata";
+
+            var isSuccessful = DkimSignatureDataFragmentParser.TryParse(dkimSignatureRaw, out var dkimSignatureDataFragment, out var parsingResults);
+
+            Assert.IsTrue(isSuccessful);
+            Assert.IsNotNull(dkimSignatureDataFragment);
+            Assert.IsNotNull(parsingResults, "ParsingResults is null");
+        }
+    }
+}

src/Nager.EmailAuthentication/DkimSignatureDataFragmentParser.cs

@@ -381,7 +381,7 @@ private static ParsingResult[] ValidateSignedHeaderFields(ValidateRequest valida
                 {
                     Status = ParsingStatus.Error,
                     Field = validateRequest.Field,
-                    Message = "Is empty"
+                    Message = "The signed header fields is empty, from is required"
                 });
 
                 return [.. parsingResults];
@@ -391,12 +391,10 @@ private static ParsingResult[] ValidateSignedHeaderFields(ValidateRequest valida
             {
                 parsingResults.Add(new ParsingResult
                 {
-                    Status = ParsingStatus.Error,
+                    Status = ParsingStatus.Info,
                     Field = validateRequest.Field,
-                    Message = "No colon found"
+                    Message = "No colon separator found"
                 });
-
-                return [.. parsingResults];
             }
 
             var parts = validateRequest.Value.Split(':');
@@ -417,16 +415,15 @@ private static ParsingResult[] ValidateSignedHeaderFields(ValidateRequest valida
                 }
             }
 
-            //TODO: Check important Headers
             var recommendedHeaders = new string[] { "from", "to", "subject", "reply-to", "date", "cc", "content-type" };
             var missingRecommendedHeaders = recommendedHeaders.Except(groupedHeaders.Select(o => o.Key));
             foreach (var missingRecommendedHeader in missingRecommendedHeaders)
             {
                 parsingResults.Add(new ParsingResult
                 {
-                    Status = ParsingStatus.Info,
+                    Status = ParsingStatus.Warning,
                     Field = validateRequest.Field,
-                    Message = $"Missing recommended header detected {missingRecommendedHeader}"
+                    Message = $"Missing recommended header detected '{missingRecommendedHeader}'"
                 });
             }
 

src/Nager.EmailAuthentication/DkimSignatureParser.cs

@@ -151,6 +151,8 @@ public static bool TryParse(
                 }
             }
 
+            var signedHeaders = dkimSignatureDataFragment.SignedHeaderFields.Split(':', StringSplitOptions.TrimEntries);
+
             dkimSignature = new DkimSignature
             {
                 Version = dkimSignatureDataFragment.Version,
@@ -163,7 +165,7 @@ public static bool TryParse(
                 SignatureAlgorithm = signatureAlgorithm.Value,
                 SignatureExpiration = signatureExpiration,
                 AgentOrUserIdentifier = dkimSignatureDataFragment.AgentOrUserIdentifier,
-                SignedHeaderFields = dkimSignatureDataFragment.SignedHeaderFields.Split(':'),
+                SignedHeaderFields = signedHeaders,
                 MessageCanonicalizationHeader = messageCanonicalizationHeader,
                 MessageCanonicalizationBody = messageCanonicalizationBody,
                 Timestamp = timestamp

src/Nager.EmailAuthentication/DmarcRecordDataFragmentParser.cs

@@ -310,7 +310,7 @@ private static ParsingResult[] ValidateFailureReportingOptions(ValidateRequest v
                 {
                     Status = ParsingStatus.Error,
                     Field = validateRequest.Field,
-                    Message = "No colon found"
+                    Message = "No colon separator found"
                 });
 
                 return [.. parsingResults];

src/Nager.EmailAuthentication/Nager.EmailAuthentication.csproj

@@ -20,7 +20,7 @@
 
     <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
 
-    <Version>1.6.0</Version>
+    <Version>1.6.1</Version>
   </PropertyGroup>
 
   <ItemGroup>