From 3bd75f6ce5ab9dd01e7ad2a7b2fe055fd5f404c5 Mon Sep 17 00:00:00 2001
From: Moritz Halbritter <moritz.halbritter@broadcom.com>
Date: Thu, 13 Mar 2025 11:26:23 +0100
Subject: [PATCH] Revert back to the custom decode method for Otel decoding

https://github.com/spring-projects/spring-framework/issues/34570

See gh-44677
---
 .../OpenTelemetryResourceAttributes.java      | 42 ++++++++++++++++++-
 .../OpenTelemetryResourceAttributesTests.java |  4 +-
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributes.java b/spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributes.java
index 4e94ed213f..f68d14f3fd 100644
--- a/spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributes.java
+++ b/spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributes.java
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.autoconfigure.opentelemetry;
 
+import java.io.ByteArrayOutputStream;
 import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 import java.util.LinkedHashMap;
@@ -138,7 +139,7 @@ public final class OpenTelemetryResourceAttributes {
 			if (index > 0) {
 				String key = attribute.substring(0, index);
 				String value = attribute.substring(index + 1);
-				attributes.put(key.trim(), StringUtils.uriDecode(value.trim(), StandardCharsets.UTF_8));
+				attributes.put(key.trim(), decode(value.trim()));
 			}
 		}
 		String otelServiceName = getEnv("OTEL_SERVICE_NAME");
@@ -152,4 +153,43 @@ public final class OpenTelemetryResourceAttributes {
 		return this.getEnv.apply(name);
 	}
 
+	/**
+	 * Decodes a percent-encoded string. Converts sequences like '%HH' (where HH
+	 * represents hexadecimal digits) back into their literal representations.
+	 * <p>
+	 * Inspired by {@code org.apache.commons.codec.net.PercentCodec}.
+	 * @param value value to decode
+	 * @return the decoded string
+	 */
+	private static String decode(String value) {
+		if (value.indexOf('%') < 0) {
+			return value;
+		}
+		byte[] bytes = value.getBytes(StandardCharsets.UTF_8);
+		ByteArrayOutputStream bos = new ByteArrayOutputStream(bytes.length);
+		for (int i = 0; i < bytes.length; i++) {
+			byte b = bytes[i];
+			if (b != '%') {
+				bos.write(b);
+				continue;
+			}
+			int u = decodeHex(bytes, i + 1);
+			int l = decodeHex(bytes, i + 2);
+			if (u >= 0 && l >= 0) {
+				bos.write((u << 4) + l);
+			}
+			else {
+				throw new IllegalArgumentException(
+						"Failed to decode percent-encoded characters at index %d in the value: '%s'".formatted(i,
+								value));
+			}
+			i += 2;
+		}
+		return bos.toString(StandardCharsets.UTF_8);
+	}
+
+	private static int decodeHex(byte[] bytes, int index) {
+		return (index < bytes.length) ? Character.digit(bytes[index], 16) : -1;
+	}
+
 }
diff --git a/spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributesTests.java b/spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributesTests.java
index 799c7175de..4b6f139ee3 100644
--- a/spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributesTests.java
+++ b/spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/opentelemetry/OpenTelemetryResourceAttributesTests.java
@@ -121,7 +121,7 @@ class OpenTelemetryResourceAttributesTests {
 	void illegalArgumentExceptionShouldBeThrownWhenDecodingIllegalHexCharPercentEncodedValue() {
 		this.environmentVariables.put("OTEL_RESOURCE_ATTRIBUTES", "key=abc%ß");
 		assertThatIllegalArgumentException().isThrownBy(this::getAttributes)
-			.withMessage("Invalid encoded sequence \"%ß\"");
+			.withMessage("Failed to decode percent-encoded characters at index 3 in the value: 'abc%ß'");
 	}
 
 	@Test
@@ -134,7 +134,7 @@ class OpenTelemetryResourceAttributesTests {
 	void illegalArgumentExceptionShouldBeThrownWhenDecodingInvalidPercentEncodedValue() {
 		this.environmentVariables.put("OTEL_RESOURCE_ATTRIBUTES", "key=%");
 		assertThatIllegalArgumentException().isThrownBy(this::getAttributes)
-			.withMessage("Invalid encoded sequence \"%\"");
+			.withMessage("Failed to decode percent-encoded characters at index 0 in the value: '%'");
 	}
 
 	@Test