Remove git hash from client user agent (#471)

Author: JamesNK

src/Grpc.Net.Client/Internal/GrpcProtocolConstants.cs

@@ -58,18 +58,21 @@ static GrpcProtocolConstants()
         {
             var userAgent = "grpc-dotnet";
 
+            // Use the assembly file version in the user agent.
+            // We are not using `AssemblyInformationalVersionAttribute` because Source Link appends
+            // the git hash to it, and sending a long user agent has perf implications.
             var assemblyVersion = typeof(GrpcProtocolConstants)
                 .Assembly
-                .GetCustomAttributes<AssemblyInformationalVersionAttribute>()
+                .GetCustomAttributes<AssemblyFileVersionAttribute>()
                 .FirstOrDefault();
 
             Debug.Assert(assemblyVersion != null);
 
-            // assembly version attribute should always be present
-            // but in case it isn't then don't include version in user-agent
+            // Assembly file version attribute should always be present,
+            // but in case it isn't then don't include version in user-agent.
             if (assemblyVersion != null)
             {
-                userAgent += "/" + assemblyVersion.InformationalVersion;
+                userAgent += "/" + assemblyVersion.Version;
             }
 
             UserAgentHeader = ProductInfoHeaderValue.Parse(userAgent);

test/Grpc.Net.Client.Tests/AsyncUnaryCallTests.cs

@@ -75,6 +75,11 @@ public async Task AsyncUnaryCall_Success_HttpRequestMessagePopulated()
             Assert.AreEqual(GrpcProtocolConstants.UserAgentHeader, userAgent);
             Assert.AreEqual("grpc-dotnet", userAgent.Product.Name);
             Assert.IsTrue(!string.IsNullOrEmpty(userAgent.Product.Version));
+
+            // Santity check that the user agent doesn't have the git hash in it and isn't too long.
+            // Sending a long user agent with each call has performance implications.
+            Assert.IsTrue(!userAgent.Product.Version.Contains('+'));
+            Assert.IsTrue(userAgent.Product.Version.Length <= 10);
         }
 
         [Test]