[MCC-261721] Don't break on 128bit X-B3-TraceId by tossing high bits

src/Medidata.ZipkinTracer.Core/TraceProvider.cs

@@ -66,7 +66,7 @@ internal TraceProvider(IZipkinConfig config, IOwinContext context = null)
                 }
 
                 // zipkin use the following X-Headers to propagate the trace information
-                headerTraceId = context.Request.Headers[TraceIdHeaderName];
+                headerTraceId = GetLower16Characters(context.Request.Headers[TraceIdHeaderName]);
                 headerSpanId = context.Request.Headers[SpanIdHeaderName];
                 headerParentSpanId = context.Request.Headers[ParentSpanIdHeaderName];
                 headerSampled = context.Request.Headers[SampledHeaderName];
@@ -120,8 +120,19 @@ public ITraceProvider GetNext()
         /// <returns>true: parsed</returns>
         private bool Parse(string value)
         {
-            long result;
-            return !string.IsNullOrWhiteSpace(value) && Int64.TryParse(value, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out result);
+            ulong result;
+            return !string.IsNullOrWhiteSpace(value) && UInt64.TryParse(value, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out result);
+        }
+
+        /// <summary>
+        /// Get Lower 16 Characters of an id
+        /// </summary>
+        /// <param name="value"></param>
+        /// <returns></returns>
+        private string GetLower16Characters(string value)
+        {
+            if (string.IsNullOrWhiteSpace(value)) return value;
+            return value.Length > 16 ? value.Substring(value.Length - 16) : value;
         }
 
         /// <summary>

tests/Medidata.ZipkinTracer.Core.Test/TraceProviderTests.cs

@@ -218,5 +218,86 @@ public void GetNext()
             Assert.AreEqual(sut.SpanId, nextTraceProvider.ParentSpanId);
             Assert.AreEqual(sut.IsSampled, nextTraceProvider.IsSampled);
         }
+
+        [TestMethod]
+        public void TraceIdWithLessThan16Characters()
+        {
+            // Arrange
+            var fixture = new Fixture();
+            var traceId = "48485a3953bb612";
+
+            var context = GenerateContext(
+                traceId,
+                Convert.ToString(fixture.Create<long>(), 16),
+                Convert.ToString(fixture.Create<long>(), 16),
+                fixture.Create<bool>());
+
+            // Act
+            var sut = new TraceProvider(new ZipkinConfig(), context);
+
+            // Assert
+            Assert.AreEqual(traceId, sut.TraceId);
+        }
+
+        [TestMethod]
+        public void TraceIdWith16Characters()
+        {
+            // Arrange
+            var fixture = new Fixture();
+            var traceId = "48485a3953bb6124";
+
+            var context = GenerateContext(
+                traceId,
+                Convert.ToString(fixture.Create<long>(), 16),
+                Convert.ToString(fixture.Create<long>(), 16),
+                fixture.Create<bool>());
+
+            // Act
+            var sut = new TraceProvider(new ZipkinConfig(), context);
+
+            // Assert
+            Assert.AreEqual(traceId, sut.TraceId);
+        }
+
+        [TestMethod]
+        public void TraceIdWith32Characters()
+        {
+            // Arrange
+            var fixture = new Fixture();
+            var traceIdLower16Chars = "48485a3953bb6124";
+            var traceId = "18485a3953bb6124" + traceIdLower16Chars;
+
+            var context = GenerateContext(
+                traceId,
+                Convert.ToString(fixture.Create<long>(), 16),
+                Convert.ToString(fixture.Create<long>(), 16),
+                fixture.Create<bool>());
+
+            // Act
+            var sut = new TraceProvider(new ZipkinConfig(), context);
+
+            // Assert
+            Assert.AreEqual(traceIdLower16Chars, sut.TraceId);
+        }
+
+        private IOwinContext GenerateContext(string traceId, string spanId, string parentSpanId, bool isSampled)
+        {
+            var context = MockRepository.GenerateStub<IOwinContext>();
+            var request = MockRepository.GenerateStub<IOwinRequest>();
+            var headers = new HeaderDictionary(new Dictionary<string, string[]>
+            {
+                { TraceProvider.TraceIdHeaderName, new [] { traceId } },
+                { TraceProvider.SpanIdHeaderName, new [] { spanId } },
+                { TraceProvider.ParentSpanIdHeaderName, new [] { parentSpanId } },
+                { TraceProvider.SampledHeaderName, new [] { isSampled.ToString() } }
+            });
+            var environment = new Dictionary<string, object>();
+
+            request.Stub(x => x.Headers).Return(headers);
+            context.Stub(x => x.Request).Return(request);
+            context.Stub(x => x.Environment).Return(environment);
+
+            return context;
+        }
     }
 }