Fix forwarded host formatting

Follow-up to recent commit
75e2e2c

Closes gh-34253

Author: rstoyanchev

spring-web/src/main/java/org/springframework/web/util/ForwardedHeaderUtils.java

@@ -181,7 +181,8 @@ private static void adaptForwardedHost(UriComponentsBuilder uriComponentsBuilder
 		String forHeader = headers.getFirst("X-Forwarded-For");
 		if (StringUtils.hasText(forHeader)) {
 			String host = StringUtils.tokenizeToStringArray(forHeader, ",")[0];
-			host = (!host.startsWith("[") && !host.endsWith("]") ? "[" + host + "]" : host);
+			boolean ipv6 = (host.indexOf(':') != -1);
+			host = (ipv6 && !host.startsWith("[") && !host.endsWith("]") ? "[" + host + "]" : host);
 			return InetSocketAddress.createUnresolved(host, port);
 		}
 

spring-web/src/test/java/org/springframework/web/filter/ForwardedHeaderFilterTests.java

@@ -481,7 +481,7 @@ void xForwardedForSingleIdentifier() throws Exception {
 			request.addHeader(X_FORWARDED_FOR, "203.0.113.195");
 			HttpServletRequest actual = filterAndGetWrappedRequest();
 
-			assertThat(actual.getRemoteAddr()).isEqualTo(actual.getRemoteHost()).isEqualTo("[203.0.113.195]");
+			assertThat(actual.getRemoteAddr()).isEqualTo(actual.getRemoteHost()).isEqualTo("203.0.113.195");
 			assertThat(actual.getRemotePort()).isEqualTo(MockHttpServletRequest.DEFAULT_SERVER_PORT);
 		}
 
@@ -490,7 +490,7 @@ void xForwardedForMultipleIdentifiers() throws Exception {
 			request.addHeader(X_FORWARDED_FOR, "203.0.113.195, 70.41.3.18, 150.172.238.178");
 			HttpServletRequest actual = filterAndGetWrappedRequest();
 
-			assertThat(actual.getRemoteAddr()).isEqualTo(actual.getRemoteHost()).isEqualTo("[203.0.113.195]");
+			assertThat(actual.getRemoteAddr()).isEqualTo(actual.getRemoteHost()).isEqualTo("203.0.113.195");
 			assertThat(actual.getRemotePort()).isEqualTo(MockHttpServletRequest.DEFAULT_SERVER_PORT);
 		}
 

spring-web/src/test/java/org/springframework/web/server/adapter/ForwardedHeaderTransformerTests.java

@@ -230,7 +230,7 @@ void xForwardedFor() {
 
 		request = this.requestMutator.apply(request);
 		assertThat(request.getRemoteAddress()).isNotNull();
-		assertThat(request.getRemoteAddress().getHostName()).isEqualTo("[203.0.113.195]");
+		assertThat(request.getRemoteAddress().getHostName()).isEqualTo("203.0.113.195");
 	}