[Azure.Core] UrlEncode OS description in user-agent header value if i…

…t contains non-ASCII characters (#44386)

* add html encode

* url encode if non ascii character is found

* tweak

* clean up usings

* feedback

sdk/core/Azure.Core/CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Bugs Fixed
 
+- Fixed User-Agent telemetry so that it properly escapes operating system information if it contains non-ascii characters.
 - Fix for operation id not set of incomplete long-running operation.
 
 ### Other Changes

sdk/core/Azure.Core/src/TelemetryDetails.cs

@@ -2,11 +2,9 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Generic;
-using System.ComponentModel;
+using System.Net;
 using System.Net.Http.Headers;
 using System.Reflection;
-using System.Runtime.InteropServices;
 using System.Text;
 using Azure.Core.Pipeline;
 
@@ -88,7 +86,19 @@ internal static string GenerateUserAgentString(Assembly clientAssembly, string?
                 version = version.Substring(0, hashSeparator);
             }
             runtimeInformation ??= new RuntimeInformationWrapper();
-            var platformInformation = EscapeProductInformation($"({runtimeInformation.FrameworkDescription}; {runtimeInformation.OSDescription})");
+
+            // RFC 9110 section 5.5 https://www.rfc-editor.org/rfc/rfc9110.txt#section-5.5 does not require any specific encoding : "Fields needing a greater range of characters
+            // can use an encoding, such as the one defined in RFC8187." RFC8187 is targeted at parameter values, almost always filename, so using url encoding here instead, which is
+            // more widely used. Since user-agent does not usually contain non-ascii, only encode when necessary.
+            // This was added to support operating systems with non-ascii characters in their release names.
+            string osDescription;
+#if NET8_0_OR_GREATER
+            osDescription = Ascii.IsValid(runtimeInformation.OSDescription) ? runtimeInformation.OSDescription : WebUtility.UrlEncode(runtimeInformation.OSDescription);
+#else
+            osDescription = ContainsNonAscii(runtimeInformation.OSDescription) ? WebUtility.UrlEncode(runtimeInformation.OSDescription) : runtimeInformation.OSDescription;
+#endif
+
+            var platformInformation = EscapeProductInformation($"({runtimeInformation.FrameworkDescription}; {osDescription})");
 
             return applicationId != null
                 ? $"{applicationId} azsdk-net-{assemblyName}/{version} {platformInformation}"
@@ -161,5 +171,17 @@ private static string EscapeProductInformation(string productInfo)
             sb.Append(')');
             return sb.ToString();
         }
+
+        private static bool ContainsNonAscii(string value)
+        {
+            foreach (char c in value)
+            {
+                if ((int)c > 0x7f)
+                {
+                    return true;
+                }
+            }
+            return false;
+        }
     }
 }

sdk/core/Azure.Core/tests/TelemetryDetailsTests.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT License.
 
 using System;
+using System.Net;
 using System.Reflection;
 using System.Runtime.InteropServices;
 using Azure.Core.Pipeline;
@@ -97,6 +98,52 @@ public void ValidatesProperParenthesisMatching(string input, string output)
                     target.ToString());
         }
 
+        [Test]
+        [TestCase("Win64; x64", "Win64; x64")]
+        [TestCase("Intel Mac OS X 10_15_7", "Intel Mac OS X 10_15_7")]
+        [TestCase("Android 10; SM-G973F", "Android 10; SM-G973F")]
+        [TestCase("Win64; x64; Xbox; Xbox One", "Win64; x64; Xbox; Xbox One")]
+        public void AsciiDoesNotEncode(string input, string output)
+        {
+            var mockRuntimeInformation = new MockRuntimeInformation { OSDescriptionMock = input, FrameworkDescriptionMock = RuntimeInformation.FrameworkDescription };
+            var assembly = Assembly.GetAssembly(GetType());
+            AssemblyInformationalVersionAttribute versionAttribute = assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>();
+            string version = versionAttribute.InformationalVersion;
+            int hashSeparator = version.IndexOfOrdinal('+');
+            if (hashSeparator != -1)
+            {
+                version = version.Substring(0, hashSeparator);
+            }
+
+            var target = new TelemetryDetails(typeof(TelemetryDetailsTests).Assembly, default, mockRuntimeInformation);
+
+            Assert.AreEqual(
+                    $"azsdk-net-Core.Tests/{version} ({mockRuntimeInformation.FrameworkDescription}; {output})",
+                    target.ToString());
+        }
+
+        [Test]
+        [TestCase("»-Browser¢sample", "%C2%BB-Browser%C2%A2sample")]
+        [TestCase("NixOS 24.11 (Vicuña)", "NixOS+24.11+(Vicu%C3%B1a)")]
+        public void NonAsciiCharactersAreUrlEncoded(string input, string output)
+        {
+            var mockRuntimeInformation = new MockRuntimeInformation { OSDescriptionMock = input, FrameworkDescriptionMock = RuntimeInformation.FrameworkDescription };
+            var assembly = Assembly.GetAssembly(GetType());
+            AssemblyInformationalVersionAttribute versionAttribute = assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>();
+            string version = versionAttribute.InformationalVersion;
+            int hashSeparator = version.IndexOfOrdinal('+');
+            if (hashSeparator != -1)
+            {
+                version = version.Substring(0, hashSeparator);
+            }
+
+            var target = new TelemetryDetails(typeof(TelemetryDetailsTests).Assembly, default, mockRuntimeInformation);
+
+            Assert.AreEqual(
+                    $"azsdk-net-Core.Tests/{version} ({mockRuntimeInformation.FrameworkDescription}; {output})",
+                    target.ToString());
+        }
+
         private class MockRuntimeInformation : RuntimeInformationWrapper
         {
             public string FrameworkDescriptionMock { get; set; }