Correctly set maxAge and expires in ResponseCookie

Issue: SPR-16940

spring-web/src/main/java/org/springframework/http/HttpHeaders.java

@@ -1218,9 +1218,14 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	 * @see #setZonedDateTime(String, ZonedDateTime)
 	 */
 	public void setDate(String headerName, long date) {
+		set(headerName, formatDate(date));
+	}
+
+	// Package private: also used in ResponseCookie..
+	static String formatDate(long date) {
 		Instant instant = Instant.ofEpochMilli(date);
-		ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(instant, GMT);
-		set(headerName, DATE_FORMATTERS[0].format(zonedDateTime));
+		ZonedDateTime time = ZonedDateTime.ofInstant(instant, GMT);
+		return DATE_FORMATTERS[0].format(time);
 	}
 
 	/**

spring-web/src/main/java/org/springframework/http/ResponseCookie.java

@@ -154,12 +154,10 @@ public final class ResponseCookie extends HttpCookie {
 			sb.append("; Domain=").append(this.domain);
 		}
 		if (!this.maxAge.isNegative()) {
-			sb.append("; Max-Age=").append(this.maxAge);
+			sb.append("; Max-Age=").append(this.maxAge.getSeconds());
 			sb.append("; Expires=");
-			HttpHeaders headers = new HttpHeaders();
-			long seconds = this.maxAge.getSeconds();
-			headers.setExpires(seconds > 0 ? System.currentTimeMillis() + seconds : 0);
-			sb.append(headers.getFirst(HttpHeaders.EXPIRES));
+			long millis = this.maxAge.getSeconds() > 0 ? System.currentTimeMillis() + this.maxAge.toMillis() : 0;
+			sb.append(HttpHeaders.formatDate(millis));
 		}
 		if (this.secure) {
 			sb.append("; Secure");
@@ -267,7 +265,7 @@ public final class ResponseCookie extends HttpCookie {
 		ResponseCookieBuilder maxAge(Duration maxAge);
 
 		/**
-		 * Set the cookie "Max-Age" attribute in seconds.
+		 * Variant of {@link #maxAge(Duration)} accepting a value in seconds.
 		 */
 		ResponseCookieBuilder maxAge(long maxAgeSeconds);
 
@@ -294,6 +292,9 @@ public final class ResponseCookie extends HttpCookie {
 
 		/**
 		 * Add the "SameSite" attribute to the cookie.
+		 * <p>This limits the scope of the cookie such that it will only be
+		 * attached to same site requests if {@code "Strict"} or cross-site
+		 * requests if {@code "Lax"}.
 		 * @see <a href="https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis#section-4.1.2.7">RFC6265 bis</a>
 		 */
 		ResponseCookieBuilder sameSite(String sameSite);

spring-web/src/main/java/org/springframework/web/server/session/CookieWebSessionIdResolver.java

@@ -92,7 +92,7 @@ public class CookieWebSessionIdResolver implements WebSessionIdResolver {
 	 * Return the configured "SameSite" attribute value for the session cookie.
 	 */
 	public String getSameSite() {
-		return sameSite;
+		return this.sameSite;
 	}
 
 	@Override

spring-web/src/test/java/org/springframework/http/ResponseCookieTests.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.http;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+/**
+ * Unit tests for {@link ResponseCookie}.
+ * @author Rossen Stoyanchev
+ */
+public class ResponseCookieTests {
+
+	@Test
+	public void defaultValues() {
+		assertEquals("id=1fWa", ResponseCookie.from("id", "1fWa").build().toString());
+	}
+
+	@Test
+	public void httpOnlyStrictSecureWithDomainAndPath() {
+		assertEquals("id=1fWa; Path=/projects; Domain=spring.io; Secure; HttpOnly; SameSite=strict",
+				ResponseCookie.from("id", "1fWa").domain("spring.io").path("/projects")
+						.httpOnly(true).secure(true).sameSite("strict").build().toString());
+	}
+
+	@Test
+	public void maxAge() {
+
+		Duration maxAge = Duration.ofDays(365);
+		String expires = HttpHeaders.formatDate(System.currentTimeMillis() + maxAge.toMillis());
+		expires = expires.substring(0, expires.indexOf(":") + 1);
+
+		assertThat(ResponseCookie.from("id", "1fWa").maxAge(maxAge).build().toString(), allOf(
+				startsWith("id=1fWa; Max-Age=31536000; Expires=" + expires),
+				endsWith(" GMT")));
+
+		assertThat(ResponseCookie.from("id", "1fWa").maxAge(maxAge.getSeconds()).build().toString(), allOf(
+				startsWith("id=1fWa; Max-Age=31536000; Expires=" + expires),
+				endsWith(" GMT")));
+	}
+
+	@Test
+	public void maxAge0() {
+		assertEquals("id=1fWa; Max-Age=0; Expires=Thu, 1 Jan 1970 00:00:00 GMT",
+				ResponseCookie.from("id", "1fWa").maxAge(Duration.ofSeconds(0)).build().toString());
+
+		assertEquals("id=1fWa; Max-Age=0; Expires=Thu, 1 Jan 1970 00:00:00 GMT",
+				ResponseCookie.from("id", "1fWa").maxAge(0).build().toString());
+	}
+
+}

spring-web/src/test/java/org/springframework/web/server/session/CookieWebSessionIdResolverTests.java

@@ -35,7 +35,7 @@ public class CookieWebSessionIdResolverTests {
 
 
 	@Test
-	public void setSessionId() throws Exception {
+	public void setSessionId() {
 		MockServerHttpRequest request = MockServerHttpRequest.get("https://example.org/path").build();
 		MockServerWebExchange exchange = MockServerWebExchange.from(request);
 		this.resolver.setSessionId(exchange, "123");