Optimize parse logic for invalid data

Author: tinohager

src/Nager.EmailAuthentication.UnitTest/DkimPublicKeyRecordParserTests/BasicTest.cs

@@ -38,5 +38,27 @@ public void TryParse_InvalidDkimPublicKeyRecord3_ReturnsTrueAndPopulatesDataFrag
             Assert.IsNotNull(dkimPublicKeyRecordDataFragment);
             Assert.IsNotNull(parsingResults, "ParsingResults is null");
         }
+
+        [TestMethod]
+        public void TryParse_WrongDkimPublicKeyRecord1_ReturnsTrueAndPopulatesDataFragment()
+        {
+            var dkimPublicKeyRecordRaw = "v=DMARC1;p=reject;";
+
+            var isSuccessful = DkimPublicKeyRecordDataFragmentParser.TryParse(dkimPublicKeyRecordRaw, out var dkimPublicKeyRecordDataFragment, out var parsingResults);
+
+            Assert.IsTrue(isSuccessful);
+            Assert.IsNotNull(dkimPublicKeyRecordDataFragment);
+            Assert.IsNotNull(parsingResults, "ParsingResults is null");
+        }
+
+        [TestMethod]
+        public void TryParse_WrongDkimPublicKeyRecord2_ReturnsTrueAndPopulatesDataFragment()
+        {
+            var dkimPublicKeyRecordRaw = "v=DMARC1;p=reject;";
+
+            var isSuccessful = DkimPublicKeyRecordParser.TryParse(dkimPublicKeyRecordRaw, out var dkimPublicKeyRecord);
+            Assert.IsFalse(isSuccessful);
+            Assert.IsNull(dkimPublicKeyRecord, "DkimPublicKeyRecord is not null");
+        }
     }
 }

src/Nager.EmailAuthentication/DkimPublicKeyRecordParser.cs

@@ -8,6 +8,21 @@ namespace Nager.EmailAuthentication
     /// </summary>
     public static class DkimPublicKeyRecordParser
     {
+        private static bool ValidateRaw(string? dkimPublicKeyRecordRaw)
+        {
+            if (string.IsNullOrWhiteSpace(dkimPublicKeyRecordRaw))
+            {
+                return false;
+            }
+
+            if (!dkimPublicKeyRecordRaw.StartsWith("v=DKIM1", StringComparison.OrdinalIgnoreCase))
+            {
+                return false;
+            }
+
+            return true;
+        }
+
         /// <summary>
         /// TryParse
         /// </summary>
@@ -18,6 +33,12 @@ public static bool TryParse(
             string? dkimPublicKeyRecordRaw,
             [NotNullWhen(true)] out DkimPublicKeyRecord? dkimPublicKeyRecord)
         {
+            if (!ValidateRaw(dkimPublicKeyRecordRaw))
+            {
+                dkimPublicKeyRecord = null;
+                return false;
+            }
+
             if (!DkimPublicKeyRecordDataFragmentParser.TryParse(dkimPublicKeyRecordRaw, out var dataFragment, out _))
             {
                 dkimPublicKeyRecord = null;
@@ -45,6 +66,12 @@ public static bool TryParse(
                 return false;
             }
 
+            if (!ValidateRaw(dkimPublicKeyRecordRaw))
+            {
+                dkimPublicKeyRecord = null;
+                return false;
+            }
+
             return TryParse(dataFragment, out dkimPublicKeyRecord);
         }
 

src/Nager.EmailAuthentication/DmarcRecordParser.cs

@@ -8,6 +8,21 @@ namespace Nager.EmailAuthentication
     /// </summary>
     public static class DmarcRecordParser
     {
+        private static bool ValidateRaw(string? dmarcRaw)
+        {
+            if (string.IsNullOrWhiteSpace(dmarcRaw))
+            {
+                return false;
+            }
+
+            if (!dmarcRaw.StartsWith("v=DMARC1", StringComparison.OrdinalIgnoreCase))
+            {
+                return false;
+            }
+
+            return true;
+        }
+
         /// <summary>
         /// Attempts to parse a raw DMARC record string into a <see cref="DmarcRecord"/> object.
         /// </summary>
@@ -24,6 +39,12 @@ public static bool TryParse(
             string? dmarcRaw,
             [NotNullWhen(true)] out DmarcRecord? dmarcRecord)
         {
+            if (!ValidateRaw(dmarcRaw))
+            {
+                dmarcRecord = null;
+                return false;
+            }
+
             if (!DmarcRecordDataFragmentParser.TryParse(dmarcRaw, out var dataFragment, out _))
             {
                 dmarcRecord = null;
@@ -61,6 +82,12 @@ public static bool TryParse(
                 return false;
             }
 
+            if (!ValidateRaw(dmarcRaw))
+            {
+                dmarcRecord = null;
+                return false;
+            }
+
             return TryParse(dataFragment, out dmarcRecord);
         }
 

src/Nager.EmailAuthentication/Nager.EmailAuthentication.csproj

@@ -20,7 +20,7 @@
 
     <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
 
-    <Version>1.5.8</Version>
+    <Version>1.5.9</Version>
   </PropertyGroup>
 
   <ItemGroup>