Validating when retry-after time is older than current one

Author: LikeTheSalad

opamp-client/src/main/java/io/opentelemetry/opamp/client/internal/connectivity/http/RetryAfterParser.java

@@ -10,6 +10,7 @@
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
 import java.util.Locale;
+import java.util.Optional;
 import java.util.regex.Pattern;
 
 public final class RetryAfterParser {
@@ -29,13 +30,17 @@ public static RetryAfterParser getInstance() {
     this.systemTime = systemTime;
   }
 
-  public Duration parse(String value) {
+  public Optional<Duration> tryParse(String value) {
+    Duration duration = null;
     if (SECONDS_PATTERN.matcher(value).matches()) {
-      return Duration.ofSeconds(Long.parseLong(value));
+      duration = Duration.ofSeconds(Long.parseLong(value));
     } else if (DATE_PATTERN.matcher(value).matches()) {
-      return Duration.ofMillis(toMilliseconds(value) - systemTime.getCurrentTimeMillis());
+      long difference = toMilliseconds(value) - systemTime.getCurrentTimeMillis();
+      if (difference > 0) {
+        duration = Duration.ofMillis(difference);
+      }
     }
-    throw new IllegalArgumentException("Invalid Retry-After value: " + value);
+    return Optional.ofNullable(duration);
   }
 
   private static long toMilliseconds(String value) {

opamp-client/src/main/java/io/opentelemetry/opamp/client/internal/request/service/HttpRequestService.java

@@ -17,6 +17,7 @@
 import java.io.OutputStream;
 import java.time.Duration;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
@@ -164,7 +165,10 @@ private void handleHttpError(HttpSender.Response response) {
       String retryAfterHeader = response.getHeader("Retry-After");
       Duration retryAfter = null;
       if (retryAfterHeader != null) {
-        retryAfter = retryAfterParser.parse(retryAfterHeader);
+        Optional<Duration> duration = retryAfterParser.tryParse(retryAfterHeader);
+        if (duration.isPresent()) {
+          retryAfter = duration.get();
+        }
       }
       enableRetryMode(retryAfter);
     }

opamp-client/src/test/java/io/opentelemetry/opamp/client/internal/connectivity/http/RetryAfterParserTest.java

@@ -18,12 +18,17 @@ class RetryAfterParserTest {
   @Test
   void verifyParsing() {
     SystemTime systemTime = mock();
-    long currentTimeMillis = 1577836800000L;
+    long currentTimeMillis = 1577836800000L; // Wed, 01 Jan 2020 00:00:00 GMT
     when(systemTime.getCurrentTimeMillis()).thenReturn(currentTimeMillis);
 
     RetryAfterParser parser = new RetryAfterParser(systemTime);
 
-    assertThat(parser.parse("123")).isEqualTo(Duration.ofSeconds(123));
-    assertThat(parser.parse("Wed, 01 Jan 2020 01:00:00 GMT")).isEqualTo(Duration.ofHours(1));
+    assertThat(parser.tryParse("123")).get().isEqualTo(Duration.ofSeconds(123));
+    assertThat(parser.tryParse("Wed, 01 Jan 2020 01:00:00 GMT"))
+        .get()
+        .isEqualTo(Duration.ofHours(1));
+
+    // Check when provided time is older than the current one
+    assertThat(parser.tryParse("Tue, 31 Dec 2019 23:00:00 GMT")).isNotPresent();
   }
 }