E-Mail Validierung hinzugefügt

AMWD.Common.Tests/Extensions/StringExtensionsTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using System.Net;
 using System.Text;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -245,5 +246,60 @@ namespace AMWD.Common.Tests.Extensions
 			Assert.AreEqual(number, numberEn);
 			Assert.AreEqual(number, numberDe);
 		}
+
+		[TestMethod]
+		public void ShouldValidateEmailAddressWithoutRecordCheck()
+		{
+			// arrange
+			string validEmailWithoutTag = "test@gmail.com";
+			string validEmailWithTag = "test+tag@not.exists";
+			string invalidEmailWithoutTag = "<Test Account> test@gmail.com";
+			string invalidEmailWithTag = "<Test Account> test+tag@not.exists";
+
+			// act
+			bool validWithoutTag = validEmailWithoutTag.IsValidEmailAddress(checkRecordExists: false);
+			bool validWithTag = validEmailWithTag.IsValidEmailAddress(checkRecordExists: false);
+			bool invalidWithoutTag = !invalidEmailWithoutTag.IsValidEmailAddress(checkRecordExists: false);
+			bool invalidWithTag = !invalidEmailWithTag.IsValidEmailAddress(checkRecordExists: false);
+
+			// assert
+			Assert.IsTrue(validWithoutTag);
+			Assert.IsTrue(validWithTag);
+			Assert.IsTrue(invalidWithoutTag);
+			Assert.IsTrue(invalidWithTag);
+		}
+
+		[TestMethod]
+		public void ShouldValidateEmailAddressWithRecordCheck()
+		{
+			// arrange
+			string validEmail = "test@gmail.com";
+			string invalidEmail = "test@not.exists";
+
+			// act
+			bool valid = validEmail.IsValidEmailAddress(checkRecordExists: true);
+			bool invalid = !invalidEmail.IsValidEmailAddress(checkRecordExists: true);
+
+			// assert
+			Assert.IsTrue(valid);
+			Assert.IsTrue(invalid);
+		}
+
+		[TestMethod]
+		public void ShouldValidateEmailAddressWithRecordCheckDefinedNameservers()
+		{
+			// arrange
+			string validEmail = "test@gmail.com";
+			string invalidEmail = "test@not.exists";
+			var nameserver = new IPEndPoint(IPAddress.Parse("1.1.1.1"), 53);
+
+			// act
+			bool valid = validEmail.IsValidEmailAddress(new[] { nameserver });
+			bool invalid = !invalidEmail.IsValidEmailAddress(new[] { nameserver });
+
+			// assert
+			Assert.IsTrue(valid);
+			Assert.IsTrue(invalid);
+		}
 	}
 }

AMWD.Common/AMWD.Common.csproj

@@ -36,6 +36,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="DnsClient" Version="1.5.0" />
     <PackageReference Include="Newtonsoft.Json" Version="10.0.1" />
     <PackageReference Include="Unclassified.DeepConvert" Version="1.3.0" />
     <PackageReference Include="Unclassified.NetRevisionTask" Version="0.4.1">

AMWD.Common/Extensions/StringExtensions.cs

@@ -1,8 +1,11 @@
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
+using System.Net;
+using System.Net.Mail;
 using System.Text;
 using System.Text.RegularExpressions;
+using DnsClient;
 
 namespace System
 {
@@ -137,5 +140,50 @@ namespace System
 
 			return decimal.Parse(decString, culture);
 		}
+
+		/// <summary>
+		/// Checks whether the given <see cref="string"/> is a valid <see cref="MailAddress"/>.
+		/// </summary>
+		/// <remarks>
+		/// You can enhance the check by requesting the MX record of the domain.
+		/// </remarks>
+		/// <param name="email">The email address as string to validate.</param>
+		/// <param name="checkRecordExists">A value indicating whether to resolve a MX record.</param>
+		/// <returns><c>true</c> when the email address is valid, other wise <c>false</c>.</returns>
+		public static bool IsValidEmailAddress(this string email, bool checkRecordExists = false)
+			=> email.IsValidEmailAddress(checkRecordExists ? new LookupClient() : null);
+
+		/// <summary>
+		/// Checks whether the given <see cref="string"/> is a valid <see cref="MailAddress"/>.
+		/// </summary>
+		/// <remarks>
+		/// The check is enhanced by a request for MX records on the defined <paramref name="nameservers"/>.
+		/// </remarks>
+		/// <param name="email">The email address as string to validate.</param>
+		/// <param name="nameservers">A list of <see cref="IPEndPoint"/>s of nameservers.</param>
+		/// <returns><c>true</c> when the email address is valid, other wise <c>false</c>.</returns>
+		public static bool IsValidEmailAddress(this string email, IEnumerable<IPEndPoint> nameservers)
+			=> email.IsValidEmailAddress(new LookupClient(nameservers.ToArray()));
+
+		private static bool IsValidEmailAddress(this string email, LookupClient lookupClient)
+		{
+			try
+			{
+				var mailAddress = new MailAddress(email);
+				bool isValid = mailAddress.Address == email;
+
+				if (isValid && lookupClient != null)
+				{
+					var result = lookupClient.Query(mailAddress.Host, QueryType.MX);
+					isValid &= result.Answers.MxRecords().Any();
+				}
+
+				return isValid;
+			}
+			catch
+			{
+				return false;
+			}
+		}
 	}
 }

README.md

@@ -8,7 +8,7 @@ To save time, they are all packed to NuGet packages.
 | AMWD.Common                     | ![https://nuget.am-wd.de/packages/amwd.common/](https://img.shields.io/badge/dynamic/json?color=blue&label=AMWD.Common&query=%24.versions[-1%3A]&url=https%3A%2F%2Fnuget.am-wd.de%2Fv3%2Fpackage%2Famwd.common%2Findex.json&style=flat-square) |
 | AMWD.Common.AspNetCore          | ![https://nuget.am-wd.de/packages/amwd.common.aspnetcore/](https://img.shields.io/badge/dynamic/json?color=blue&label=AMWD.Common.AspNetCore&query=%24.versions[-1%3A]&url=https%3A%2F%2Fnuget.am-wd.de%2Fv3%2Fpackage%2Famwd.common.aspnetcore%2Findex.json&style=flat-square) |
 | AMWD.Common.EntityFrameworkCore | ![https://nuget.am-wd.de/packages/amwd.common.entityframeworkcore/](https://img.shields.io/badge/dynamic/json?color=blue&label=AMWD.Common.EntityFrameworkCore&query=%24.versions[-1%3A]&url=https%3A%2F%2Fnuget.am-wd.de%2Fv3%2Fpackage%2Famwd.common.entityframeworkcore%2Findex.json&style=flat-square) |
-| Build Pipeline                  | ![https://git.am-wd.de/AM.WD/common/-/commits/master](https://git.am-wd.de/AM.WD/common/badges/master/pipeline.svg?style=flat-square) |
+| CI / CD                         | ![https://git.am-wd.de/AM.WD/common/-/pipelines](https://git.am-wd.de/AM.WD/common/badges/master/pipeline.svg?style=flat-square) ![https://git.am-wd.de/AM.WD/common/-/tree/master](https://git.am-wd.de/AM.WD/common/badges/master/coverage.svg?style=flat-square) |
 
 ## Documentation