refactor: do not resolve ip addresses

Make sure that if a remote IP address is specified, do not DNS resolve it.

src/Serilog.Sinks.Udp/Sinks/Udp/Private/IUdpClient.cs

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+using System.Net;
 using System.Threading.Tasks;
 
 namespace Serilog.Sinks.Udp.Private
@@ -21,6 +22,22 @@ namespace Serilog.Sinks.Udp.Private
     /// </summary>
     public interface IUdpClient
     {
+        /// <summary>
+        /// Sends a UDP datagram asynchronously to a remote host.
+        /// </summary>
+        /// <param name="datagram">
+        /// An array of type <see cref="byte"/> that specifies the UDP datagram that you intend to
+        /// send represented as an array of bytes.
+        /// </param>
+        /// <param name="bytes">
+        /// The number of bytes in the datagram.
+        /// </param>
+        /// <param name="endPoint">
+        /// An <see cref="IPEndPoint"/> that represents the host and port to which to send the datagram.
+        /// </param>
+        /// <returns></returns>
+        Task<int> SendAsync(byte[] datagram, int bytes, IPEndPoint endPoint);
+
         /// <summary>
         /// Sends a UDP datagram asynchronously to a remote host.
         /// </summary>

src/Serilog.Sinks.Udp/Sinks/Udp/Private/RemoteEndPoint.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Net;
+
+namespace Serilog.Sinks.Udp.Private
+{
+    internal class RemoteEndPoint
+    {
+        public RemoteEndPoint(string address, int port)
+        {
+            if (port < IPEndPoint.MinPort || port > IPEndPoint.MaxPort) throw new ArgumentOutOfRangeException(nameof(port));
+
+            Address = address ?? throw new ArgumentNullException(nameof(address));
+            Port = port;
+
+            if (IPAddress.TryParse(address, out var ipAddress))
+            {
+                IPEndPoint = new IPEndPoint(ipAddress, port);
+            }
+        }
+
+        public string Address { get; }
+
+        public int Port { get; }
+
+        public IPEndPoint IPEndPoint { get; }
+    }
+}

src/Serilog.Sinks.Udp/Sinks/Udp/Private/UdpClientWrapper.cs

@@ -32,6 +32,11 @@ public UdpClientWrapper(int localPort)
                 : new UdpClient(localPort, AddressFamily.InterNetwork);
         }
 
+        public Task<int> SendAsync(byte[] datagram, int bytes, IPEndPoint endPoint)
+        {
+            return client.SendAsync(datagram, bytes, endPoint);
+        }
+
         public Task<int> SendAsync(byte[] datagram, int bytes, string hostname, int port)
         {
             return client.SendAsync(datagram, bytes, hostname, port);

src/Serilog.Sinks.Udp/Sinks/Udp/Private/UdpSink.cs

@@ -15,7 +15,6 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using System.Net;
 using System.Text;
 using System.Threading.Tasks;
 using Serilog.Debugging;
@@ -31,8 +30,7 @@ namespace Serilog.Sinks.Udp.Private
     internal class UdpSink : PeriodicBatchingSink
     {
         private readonly IUdpClient client;
-        private readonly string remoteAddress;
-        private readonly int remotePort;
+        private readonly RemoteEndPoint remoteEndPoint;
         private readonly ITextFormatter formatter;
 
         public UdpSink(
@@ -42,11 +40,8 @@ public UdpSink(
             ITextFormatter formatter)
             : base(1000, TimeSpan.FromSeconds(0.5))
         {
-            if (remotePort < IPEndPoint.MinPort || remotePort > IPEndPoint.MaxPort) throw new ArgumentOutOfRangeException(nameof(remotePort));
-
             this.client = client ?? throw new ArgumentNullException(nameof(client));
-            this.remoteAddress = remoteAddress ?? throw new ArgumentNullException(nameof(remoteAddress));
-            this.remotePort = remotePort;
+            remoteEndPoint = new RemoteEndPoint(remoteAddress, remotePort);
             this.formatter = formatter ?? throw new ArgumentNullException(nameof(formatter));
         }
 
@@ -69,9 +64,18 @@ protected override async Task EmitBatchAsync(IEnumerable<LogEvent> events)
                                 .Trim()
                                 .ToCharArray());
 
-                        await client
-                            .SendAsync(buffer, buffer.Length, remoteAddress, remotePort)
-                            .ConfigureAwait(false);
+                        if (remoteEndPoint.IPEndPoint != null)
+                        {
+                            await client
+                                .SendAsync(buffer, buffer.Length, remoteEndPoint.IPEndPoint)
+                                .ConfigureAwait(false);
+                        }
+                        else
+                        {
+                            await client
+                                .SendAsync(buffer, buffer.Length, remoteEndPoint.Address, remoteEndPoint.Port)
+                                .ConfigureAwait(false);
+                        }
                     }
                 }
                 catch (Exception e)

test/Serilog.Sinks.Udp.Tests/OutputTemplateGivenCodeConfigurationShould.cs

@@ -1,5 +1,4 @@
-using System.Net;
-using Serilog.Core;
+using Serilog.Core;
 using Serilog.Support;
 
 namespace Serilog
@@ -10,7 +9,7 @@ public class OutputTemplateGivenCodeConfigurationShould : SinkFixture
 
         public OutputTemplateGivenCodeConfigurationShould()
         {
-            var remoteAddress = IPAddress.Loopback.ToString();
+            var remoteAddress = "localhost";
             var remotePort = 7071;
 
             RemoteAddress = remoteAddress;

test/Serilog.Sinks.Udp.Tests/TextFormatterGivenCodeConfigurationShould.cs

@@ -1,5 +1,4 @@
-using System.Net;
-using Serilog.Core;
+using Serilog.Core;
 using Serilog.Support.TextFormatters;
 
 namespace Serilog
@@ -8,7 +7,7 @@ public class TextFormatterGivenCodeConfigurationShould : SinkFixture
     {
         public TextFormatterGivenCodeConfigurationShould()
         {
-            var remoteAddress = IPAddress.Loopback.ToString();
+            var remoteAddress = "localhost";
             var remotePort = 7071;
 
             RemoteAddress = remoteAddress;