Issue #8057 - Support Http Response 103 (Early Hints)

Improved implementation on the client-side.
Introduced HttpStatus.isInterim() for 1XX codes that are not 101.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>

jetty-client/src/main/java/org/eclipse/jetty/client/HttpReceiver.java

@@ -411,9 +411,8 @@ protected boolean responseSuccess(HttpExchange exchange)
         ResponseNotifier notifier = getHttpDestination().getResponseNotifier();
         notifier.notifySuccess(listeners, response);
 
-        // Special case for 100 Continue that cannot
-        // be handled by the ContinueProtocolHandler.
-        if (exchange.getResponse().getStatus() == HttpStatus.CONTINUE_100)
+        // Interim responses do not terminate the exchange.
+        if (HttpStatus.isInterim(exchange.getResponse().getStatus()))
             return true;
 
         // Mark atomically the response as terminated, with

jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpReceiverOverHTTP.java

@@ -187,12 +187,10 @@ private void process()
                 }
                 else if (read == 0)
                 {
-                    if (networkBuffer.isEmpty())
-                    {
-                        releaseNetworkBuffer();
-                        fillInterested();
-                        return;
-                    }
+                    assert networkBuffer.isEmpty();
+                    releaseNetworkBuffer();
+                    fillInterested();
+                    return;
                 }
                 else
                 {
@@ -256,7 +254,6 @@ private boolean parse()
                 {
                     if (LOG.isDebugEnabled())
                         LOG.debug("Discarding unexpected content after response {}: {}", status, networkBuffer);
-                    LOG.info("Discarding unexpected content after response {}: {}", status, networkBuffer);
                     networkBuffer.clear();
                 }
                 return false;
@@ -379,7 +376,7 @@ public boolean messageComplete()
         }
 
         int status = exchange.getResponse().getStatus();
-        if (status != HttpStatus.CONTINUE_100)
+        if (!HttpStatus.isInterim(status))
         {
             inMessages.increment();
             complete = true;

jetty-http/src/main/java/org/eclipse/jetty/http/HttpHeader.java

@@ -88,6 +88,7 @@ public enum HttpHeader
     AGE("Age"),
     ALT_SVC("Alt-Svc"),
     ETAG("ETag"),
+    LINK("Link"),
     LOCATION("Location"),
     PROXY_AUTHENTICATE("Proxy-Authenticate"),
     RETRY_AFTER("Retry-After"),

jetty-http/src/main/java/org/eclipse/jetty/http/HttpStatus.java

@@ -341,6 +341,17 @@ public static boolean isInformational(int code)
         return ((100 <= code) && (code <= 199));
     }
 
+    /**
+     * Tests whether the status code is informational but not {@code 101 Switching Protocols}.
+     *
+     * @param code the code to test
+     * @return whether the status code is informational but not {@code 101 Switching Protocols}
+     */
+    public static boolean isInterim(int code)
+    {
+        return isInformational(code) && code != HttpStatus.SWITCHING_PROTOCOLS_101;
+    }
+
     /**
      * Simple test against an code to determine if it falls into the
      * <code>Success</code> message category as defined in the <a

jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/HttpReceiverOverHTTP2.java

@@ -120,8 +120,7 @@ void onHeaders(Stream stream, HeadersFrame frame)
                 if (responseHeaders(exchange))
                 {
                     int status = response.getStatus();
-                    boolean informational = HttpStatus.isInformational(status) && status != HttpStatus.SWITCHING_PROTOCOLS_101;
-                    if (frame.isEndStream() || informational)
+                    if (frame.isEndStream() || HttpStatus.isInterim(status))
                         responseSuccess(exchange);
                 }
                 else

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/HttpTransportOverHTTP2.java

@@ -98,8 +98,7 @@ public void sendHeaders(MetaData.Request request, MetaData.Response response, By
         boolean isHeadRequest = HttpMethod.HEAD.is(request.getMethod());
         boolean hasContent = BufferUtil.hasContent(content) && !isHeadRequest;
         int status = response.getStatus();
-        boolean interimResponse = HttpStatus.isInformational(status) && status != HttpStatus.SWITCHING_PROTOCOLS_101;
-        if (interimResponse)
+        if (HttpStatus.isInterim(status))
         {
             // Must not commit interim responses.
             if (hasContent)

jetty-http3/http3-http-client-transport/src/main/java/org/eclipse/jetty/http3/client/http/internal/HttpReceiverOverHTTP3.java

@@ -89,8 +89,7 @@ public void onResponse(Stream.Client stream, HeadersFrame frame)
             if (responseHeaders(exchange))
             {
                 int status = response.getStatus();
-                boolean informational = HttpStatus.isInformational(status) && status != HttpStatus.SWITCHING_PROTOCOLS_101;
-                if (frame.isLast() || informational)
+                if (frame.isLast() || HttpStatus.isInterim(status))
                     responseSuccess(exchange);
                 else
                     stream.demand();

jetty-http3/http3-server/src/main/java/org/eclipse/jetty/http3/server/internal/HttpTransportOverHTTP3.java

@@ -71,8 +71,7 @@ private void sendHeaders(MetaData.Request request, MetaData.Response response, B
         boolean isHeadRequest = HttpMethod.HEAD.is(request.getMethod());
         boolean hasContent = BufferUtil.hasContent(content) && !isHeadRequest;
         int status = response.getStatus();
-        boolean interimResponse = HttpStatus.isInformational(status) && status != HttpStatus.SWITCHING_PROTOCOLS_101;
-        if (interimResponse)
+        if (HttpStatus.isInterim(status))
         {
             // Must not commit interim responses.
             if (hasContent)

jetty-server/src/main/java/org/eclipse/jetty/server/HttpChannel.java

@@ -1044,10 +1044,10 @@ protected boolean sendResponse(MetaData.Response response, ByteBuffer content, b
             _combinedListener.onResponseBegin(_request);
             _request.onResponseCommit();
 
-            // wrap callback to process 100 responses
+            // wrap callback to process informational responses
             final int status = response.getStatus();
             final Callback committed = HttpStatus.isInformational(status)
-                ? new Send100Callback(callback)
+                ? new Send1XXCallback(callback)
                 : new SendCallback(callback, content, true, complete);
 
             // committing write
@@ -1477,9 +1477,9 @@ public void failed(Throwable th)
         }
     }
 
-    private class Send100Callback extends SendCallback
+    private class Send1XXCallback extends SendCallback
     {
-        private Send100Callback(Callback callback)
+        private Send1XXCallback(Callback callback)
         {
             super(callback, null, false, false);
         }

tests/test-http-client-transport/src/test/java/org/eclipse/jetty/http/client/InformationalResponseTest.java

@@ -107,7 +107,6 @@ public void onSuccess(Response response)
                         {
                             // All good, continue.
                             exchange.resetResponse();
-                            exchange.proceed(null);
                         }
                         else
                         {
@@ -197,7 +196,6 @@ public void onSuccess(Response response)
                             // All good, continue.
                             hints.add(response.getHeaders().get("Hint"));
                             exchange.resetResponse();
-                            exchange.proceed(null);
                         }
                         else
                         {