Improved handling of 100 Continue (#12113)

* Now `HttpClient` removed the `Expect` header if there is no request content.
* Changed AbstractProxyServlet and ProxyHandler check for request content: now the Content-Type header is not taken into consideration.
* Now the server avoids sending the 100 Continue response if there is no request content.
* Now the request body is not defaulted if missing, but just kept null.

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

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/ContinueProtocolHandler.java

@@ -39,10 +39,14 @@ public String getName()
     @Override
     public boolean accept(Request request, Response response)
     {
-        boolean is100 = response.getStatus() == HttpStatus.CONTINUE_100;
-        boolean expect100 = request.getHeaders().contains(HttpHeader.EXPECT, HttpHeaderValue.CONTINUE.asString());
         boolean handled100 = request.getAttributes().containsKey(ATTRIBUTE);
-        return (is100 || expect100) && !handled100;
+        if (handled100)
+            return false;
+        boolean is100 = response.getStatus() == HttpStatus.CONTINUE_100;
+        if (is100)
+            return true;
+        // Also handle non-100 responses, because we need to complete the request to complete the whole exchange.
+        return request.getHeaders().contains(HttpHeader.EXPECT, HttpHeaderValue.CONTINUE.asString());
     }
 
     @Override

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/transport/HttpConnection.java

@@ -20,7 +20,6 @@
 
 import org.eclipse.jetty.client.Authentication;
 import org.eclipse.jetty.client.AuthenticationStore;
-import org.eclipse.jetty.client.BytesRequestContent;
 import org.eclipse.jetty.client.HttpClient;
 import org.eclipse.jetty.client.HttpProxy;
 import org.eclipse.jetty.client.HttpRequestException;
@@ -35,6 +34,7 @@
 import org.eclipse.jetty.io.CyclicTimeouts;
 import org.eclipse.jetty.util.Attachable;
 import org.eclipse.jetty.util.NanoTime;
+import org.eclipse.jetty.util.StringUtil;
 import org.eclipse.jetty.util.thread.AutoLock;
 import org.eclipse.jetty.util.thread.Scheduler;
 import org.slf4j.Logger;
@@ -146,7 +146,7 @@ protected void normalizeRequest(HttpRequest request)
 
         // Make sure the path is there
         String path = request.getPath();
-        if (path.trim().length() == 0)
+        if (StringUtil.isBlank(path))
         {
             path = "/";
             request.path(path);
@@ -191,22 +191,15 @@ protected void normalizeRequest(HttpRequest request)
 
         // Add content headers.
         Request.Content content = request.getBody();
-        if (content == null)
-        {
-            request.body(new BytesRequestContent());
-        }
-        else
+        if (content != null)
         {
             if (!headers.contains(HttpHeader.CONTENT_TYPE))
             {
                 String contentType = content.getContentType();
                 if (contentType == null)
                     contentType = getHttpClient().getDefaultRequestContentType();
                 if (contentType != null)
-                {
-                    HttpField field = new HttpField(HttpHeader.CONTENT_TYPE, contentType);
-                    request.addHeader(field);
-                }
+                    request.addHeader(new HttpField(HttpHeader.CONTENT_TYPE, contentType));
             }
             long contentLength = content.getLength();
             if (contentLength >= 0)
@@ -215,6 +208,9 @@ protected void normalizeRequest(HttpRequest request)
                     request.addHeader(new HttpField.LongValueHttpField(HttpHeader.CONTENT_LENGTH, contentLength));
             }
         }
+        // RFC 9110, section 10.1.1.
+        if (content == null || content.getLength() == 0)
+            request.headers(h -> h.remove(HttpHeader.EXPECT));
 
         // Cookies.
         StringBuilder cookies = convertCookies(request.getCookies(), null);
@@ -243,7 +239,7 @@ private StringBuilder convertCookies(List<HttpCookie> cookies, StringBuilder bui
         {
             if (builder == null)
                 builder = new StringBuilder();
-            if (builder.length() > 0)
+            if (!builder.isEmpty())
                 builder.append("; ");
             builder.append(cookie.getName()).append("=").append(cookie.getValue());
         }

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/transport/HttpSender.java

@@ -528,7 +528,7 @@ protected Action process() throws Throwable
                     action.run();
 
                 // Read the request content.
-                chunk = content.read();
+                chunk = content != null ? content.read() : Content.Chunk.EOF;
             }
             if (LOG.isDebugEnabled())
                 LOG.debug("Content {} for {}", chunk, request);
@@ -539,6 +539,7 @@ protected Action process() throws Throwable
                 {
                     // No content after the headers, demand.
                     demanded = true;
+                    assert content != null;
                     content.demand(this::succeeded);
                     return Action.SCHEDULED;
                 }

jetty-core/jetty-proxy/src/main/java/org/eclipse/jetty/proxy/ProxyHandler.java

@@ -393,11 +393,12 @@ protected void addForwardedHeader(Request clientToProxyRequest, org.eclipse.jett
 
     private boolean hasContent(Request clientToProxyRequest)
     {
-        if (clientToProxyRequest.getLength() > 0)
+        long contentLength = clientToProxyRequest.getLength();
+        if (contentLength == 0)
+            return false;
+        if (contentLength > 0)
             return true;
-        HttpFields headers = clientToProxyRequest.getHeaders();
-        return headers.get(HttpHeader.CONTENT_TYPE) != null ||
-               headers.get(HttpHeader.TRANSFER_ENCODING) != null;
+        return clientToProxyRequest.getHeaders().get(HttpHeader.TRANSFER_ENCODING) != null;
     }
 
     private boolean expects100Continue(Request clientToProxyRequest)

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/internal/HttpChannelState.java

@@ -1117,8 +1117,6 @@ public String toString()
      */
     public static class ChannelResponse implements Response, Callback
     {
-        private static final CompletableFuture<Void> UNEXPECTED_100_CONTINUE = CompletableFuture.failedFuture(new IllegalStateException("100 not expected"));
-        private static final CompletableFuture<Void> COMMITTED_100_CONTINUE = CompletableFuture.failedFuture(new IllegalStateException("Committed"));
         private final ChannelRequest _request;
         private final ResponseHttpFields _httpFields;
         protected int _status;
@@ -1408,12 +1406,14 @@ public CompletableFuture<Void> writeInterim(int status, HttpFields headers)
                 if (status == HttpStatus.CONTINUE_100)
                 {
                     if (!httpChannelState._expects100Continue)
-                        return UNEXPECTED_100_CONTINUE;
+                        return CompletableFuture.failedFuture(new IllegalStateException("100 not expected"));
+                    if (_request.getLength() == 0)
+                        return CompletableFuture.completedFuture(null);
                     httpChannelState._expects100Continue = false;
                 }
 
                 if (_httpFields.isCommitted())
-                    return status == HttpStatus.CONTINUE_100 ? COMMITTED_100_CONTINUE : CompletableFuture.failedFuture(new IllegalStateException("Committed"));
+                    return CompletableFuture.failedFuture(new IllegalStateException("Committed"));
                 if (_writeCallback != null)
                     return CompletableFuture.failedFuture(new WritePendingException());
 

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/StringUtil.java

@@ -657,21 +657,7 @@ public static int indexOfControlChars(String str)
      */
     public static boolean isBlank(String str)
     {
-        if (str == null)
-        {
-            return true;
-        }
-        int len = str.length();
-        for (int i = 0; i < len; i++)
-        {
-            if (!Character.isWhitespace(str.codePointAt(i)))
-            {
-                // found a non-whitespace, we can stop searching  now
-                return false;
-            }
-        }
-        // only whitespace
-        return true;
+        return str == null || str.isBlank();
     }
 
     /**
@@ -727,21 +713,7 @@ public static int getLength(String s)
      */
     public static boolean isNotBlank(String str)
     {
-        if (str == null)
-        {
-            return false;
-        }
-        int len = str.length();
-        for (int i = 0; i < len; i++)
-        {
-            if (!Character.isWhitespace(str.codePointAt(i)))
-            {
-                // found a non-whitespace, we can stop searching  now
-                return true;
-            }
-        }
-        // only whitespace
-        return false;
+        return !isBlank(str);
     }
 
     public static boolean isHex(String str, int offset, int length)

jetty-ee10/jetty-ee10-proxy/src/main/java/org/eclipse/jetty/ee10/proxy/AbstractProxyServlet.java

@@ -456,9 +456,12 @@ protected void onProxyRewriteFailed(HttpServletRequest clientRequest, HttpServle
 
     protected boolean hasContent(HttpServletRequest clientRequest)
     {
-        return clientRequest.getContentLength() > 0 ||
-            clientRequest.getContentType() != null ||
-            clientRequest.getHeader(HttpHeader.TRANSFER_ENCODING.asString()) != null;
+        long contentLength = clientRequest.getContentLengthLong();
+        if (contentLength == 0)
+            return false;
+        if (contentLength > 0)
+            return true;
+        return clientRequest.getHeader(HttpHeader.TRANSFER_ENCODING.asString()) != null;
     }
 
     protected boolean expects100Continue(HttpServletRequest request)

jetty-ee10/jetty-ee10-proxy/src/test/java/org/eclipse/jetty/ee10/proxy/ProxyServletTest.java

@@ -20,7 +20,9 @@
 import java.io.PrintWriter;
 import java.io.Writer;
 import java.net.ConnectException;
+import java.net.InetSocketAddress;
 import java.nio.ByteBuffer;
+import java.nio.channels.SocketChannel;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -80,6 +82,7 @@
 import org.eclipse.jetty.http.HttpMethod;
 import org.eclipse.jetty.http.HttpScheme;
 import org.eclipse.jetty.http.HttpStatus;
+import org.eclipse.jetty.http.HttpTester;
 import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.server.HttpConfiguration;
 import org.eclipse.jetty.server.HttpConnectionFactory;
@@ -1703,4 +1706,80 @@ protected void service(HttpServletRequest request, HttpServletResponse response)
             assertEquals(HttpStatus.OK_200, response.getStatus());
         }
     }
+
+    @ParameterizedTest
+    @MethodSource("impls")
+    public void testExpect100ContinueContentLengthZero(Class<? extends ProxyServlet> proxyServletClass) throws Exception
+    {
+        testExpect100ContinueNoRequestContent(proxyServletClass, false);
+    }
+
+    @ParameterizedTest
+    @MethodSource("impls")
+    public void testExpect100ContinueEmptyChunkedContent(Class<? extends ProxyServlet> proxyServletClass) throws Exception
+    {
+        testExpect100ContinueNoRequestContent(proxyServletClass, true);
+    }
+
+    private void testExpect100ContinueNoRequestContent(Class<? extends ProxyServlet> proxyServletClass, boolean chunked) throws Exception
+    {
+        startServer(new HttpServlet()
+        {
+            @Override
+            protected void service(HttpServletRequest request, HttpServletResponse response) throws IOException
+            {
+                // Send the 100 Continue.
+                ServletInputStream input = request.getInputStream();
+                // Echo the content.
+                IO.copy(input, response.getOutputStream());
+            }
+        });
+        startProxy(proxyServletClass);
+
+        String authority = "localhost:" + serverConnector.getLocalPort();
+        for (int i = 0; i < 50; i++)
+        {
+            try (SocketChannel client = SocketChannel.open(new InetSocketAddress("localhost", proxyConnector.getLocalPort())))
+            {
+                String request;
+                if (chunked)
+                {
+                    request = """
+                        POST http://$A/ HTTP/1.1
+                        Host: $A
+                        Expect: 100-Continue
+                        Transfer-Encoding: chunked
+
+                        0
+
+                        """;
+                }
+                else
+                {
+                    request = """
+                        POST http://$A/ HTTP/1.1
+                        Host: $A
+                        Expect: 100-Continue
+                        Content-Length: 0
+                        
+                        """;
+                }
+                request = request.replace("$A", authority);
+                client.write(StandardCharsets.UTF_8.encode(request));
+
+                HttpTester.Input input = HttpTester.from(client);
+                HttpTester.Response response1 = HttpTester.parseResponse(input);
+                if (chunked)
+                {
+                    assertEquals(HttpStatus.CONTINUE_100, response1.getStatus());
+                    HttpTester.Response response2 = HttpTester.parseResponse(input);
+                    assertEquals(HttpStatus.OK_200, response2.getStatus());
+                }
+                else
+                {
+                    assertEquals(HttpStatus.OK_200, response1.getStatus());
+                }
+            }
+        }
+    }
 }