Fix OtlpExporterOptionsExtensions.GetHeaders incorrectly throwing for comma in header value

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptionsExtensions.cs

@@ -33,29 +33,47 @@ public static THeaders GetHeaders<THeaders>(this OtlpExporterOptions options, Ac
             optionHeaders = Uri.UnescapeDataString(optionHeaders);
             ReadOnlySpan<char> headersSpan = optionHeaders.AsSpan();
 
+            var nextEqualIndex = headersSpan.IndexOf('=');
+
+            if (nextEqualIndex == -1)
+            {
+                throw new ArgumentException("Headers provided in an invalid format.");
+            }
+
             while (!headersSpan.IsEmpty)
             {
-                int commaIndex = headersSpan.IndexOf(',');
-                ReadOnlySpan<char> pair;
-                if (commaIndex == -1)
+                var key = headersSpan.Slice(0, nextEqualIndex).Trim().ToString();
+
+                headersSpan = headersSpan.Slice(nextEqualIndex + 1);
+
+                nextEqualIndex = headersSpan.IndexOf('=');
+
+                string value;
+                if (nextEqualIndex == -1)
                 {
-                    pair = headersSpan;
+                    // Everything until the end of the string can be considered the value.
+                    value = headersSpan.Trim().ToString();
                     headersSpan = [];
                 }
                 else
                 {
-                    pair = headersSpan.Slice(0, commaIndex);
-                    headersSpan = headersSpan.Slice(commaIndex + 1);
-                }
+                    // If we have another = we need to backtrack from it
+                    // and try to find the last comma and consider that as the delimiter.
+                    var potentialValue = headersSpan.Slice(0, nextEqualIndex);
+                    var lastComma = potentialValue.LastIndexOf(',');
 
-                int equalIndex = pair.IndexOf('=');
-                if (equalIndex == -1)
-                {
-                    throw new ArgumentException("Headers provided in an invalid format.");
+                    if (lastComma == -1)
+                    {
+                        throw new ArgumentException("Headers provided in an invalid format.");
+                    }
+
+                    potentialValue = potentialValue.Slice(0, lastComma);
+
+                    value = potentialValue.Trim().ToString();
+                    headersSpan = headersSpan.Slice(lastComma + 1);
+                    nextEqualIndex -= potentialValue.Length + 1;
                 }
 
-                var key = pair.Slice(0, equalIndex).Trim().ToString();
-                var value = pair.Slice(equalIndex + 1).Trim().ToString();
                 addHeader(headers, key, value);
             }
         }

test/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests/OtlpExporterOptionsExtensionsTests.cs

@@ -49,12 +49,16 @@ public void GetHeaders_InvalidOptionHeaders_ThrowsArgumentException(string input
     [InlineData("key1=value1", "key1=value1")]
     [InlineData("key1=value1,key2=value2", "key1=value1,key2=value2")]
     [InlineData("key1=value1,key2=value2,key3=value3", "key1=value1,key2=value2,key3=value3")]
+    [InlineData("key1=value1,value2", "key1=value1,value2")]
+    [InlineData("key1=value1,value2,key2=value3", "key1=value1,value2,key2=value3")]
     [InlineData(" key1 = value1 , key2=value2 ", "key1=value1,key2=value2")]
     [InlineData("key1= value with spaces ,key2=another value", "key1=value with spaces,key2=another value")]
     [InlineData("=value1", "=value1")]
     [InlineData("key1=", "key1=")]
     [InlineData("key1=value1%2Ckey2=value2", "key1=value1,key2=value2")]
     [InlineData("key1=value1%2Ckey2=value2%2Ckey3=value3", "key1=value1,key2=value2,key3=value3")]
+    [InlineData("key1=value1%2Cvalue2", "key1=value1,value2")]
+    [InlineData("key1=value1%2Cvalue2%2Ckey2=value3", "key1=value1,value2,key2=value3")]
     public void GetHeaders_ValidAndUrlEncodedHeaders_ReturnsCorrectHeaders(string inputOptionHeaders, string expectedNormalizedOptional)
     {
         VerifyHeaders(inputOptionHeaders, expectedNormalizedOptional);
@@ -175,27 +179,16 @@ private static void VerifyHeaders(string inputOptionHeaders, string expectedNorm
         }
 
         var headers = options.GetHeaders<Dictionary<string, string>>((d, k, v) => d.Add(k, v));
-        var expectedOptional = new Dictionary<string, string>();
 
-        if (!string.IsNullOrEmpty(expectedNormalizedOptional))
-        {
-            foreach (var segment in expectedNormalizedOptional.Split([','], StringSplitOptions.RemoveEmptyEntries))
-            {
-                var parts = segment.Split(['='], 2);
-                expectedOptional.Add(parts[0].Trim(), parts[1].Trim());
-            }
-        }
+        var actual = string.Join(",", headers.Select(h => $"{h.Key}={h.Value}"));
 
-        Assert.Equal(OtlpExporterOptions.StandardHeaders.Length + expectedOptional.Count, headers.Count);
-
-        foreach (var kvp in expectedOptional)
+        var expected = expectedNormalizedOptional;
+        if (expected.Length > 0)
         {
-            Assert.Contains(headers, h => h.Key == kvp.Key && h.Value == kvp.Value);
+            expected += ',';
         }
+        expected += string.Join(",", OtlpExporterOptions.StandardHeaders.Select(h => $"{h.Key}={h.Value}"));
 
-        foreach (var std in OtlpExporterOptions.StandardHeaders)
-        {
-            Assert.Contains(headers, h => h.Key == std.Key && h.Value == std.Value);
-        }
+        Assert.Equal(expected, actual);
     }
 }