[#4754] Correctly detect websocket upgrade

Motivation:

If the Connection header contains multiple values (which is valid) we fail to detect a websocket upgrade

Modification:

- Add new method which allows to check if a header field contains a specific value (and also respect multiple header values)
- Use this method to detect handshake

Result:

Correct detect handshake if Connection header contains multiple values (seperated by ',').

codec-http/src/main/java/io/netty/handler/codec/http/HttpHeaders.java

@@ -16,6 +16,7 @@
 package io.netty.handler.codec.http;
 
 import io.netty.buffer.ByteBuf;
+import io.netty.util.internal.StringUtil;
 
 import java.text.ParseException;
 import java.util.Calendar;
@@ -1671,6 +1672,48 @@ public abstract class HttpHeaders implements Iterable<Map.Entry<String, String>>
         return false;
     }
 
+    /**
+     * Returns {@code true} if a header with the {@code name} and {@code value} exists, {@code false} otherwise.
+     * This also handles multiple values that are seperated with a {@code ,}.
+     * <p>
+     * If {@code ignoreCase} is {@code true} then a case insensitive compare is done on the value.
+     * @param name the name of the header to find
+     * @param value the value of the header to find
+     * @param ignoreCase {@code true} then a case insensitive compare is run to compare values.
+     * otherwise a case sensitive compare is run to compare values.
+     */
+    public boolean containsValue(CharSequence name, CharSequence value, boolean ignoreCase) {
+        List<String> values = getAll(name);
+        if (values.isEmpty()) {
+            return false;
+        }
+
+        for (String v: values) {
+            if (contains(v, value, ignoreCase)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private static boolean contains(String value, CharSequence expected, boolean ignoreCase) {
+        String[] parts = StringUtil.split(value, ',');
+        if (ignoreCase) {
+            for (String s: parts) {
+                if (equalsIgnoreCase(expected, s.trim())) {
+                    return true;
+                }
+            }
+        } else {
+            for (String s: parts) {
+                if (s.trim().contentEquals(expected)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
     /**
      * Returns {@code true} if a header with the name and value exists.
      *

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker00.java

@@ -196,10 +196,9 @@ public class WebSocketClientHandshaker00 extends WebSocketClientHandshaker {
                     + upgrade);
         }
 
-        String connection = headers.get(Names.CONNECTION);
-        if (!Values.UPGRADE.equalsIgnoreCase(connection)) {
+        if (!headers.containsValue(Names.CONNECTION, Values.UPGRADE, true)) {
             throw new WebSocketHandshakeException("Invalid handshake response connection: "
-                    + connection);
+                    + headers.get(Names.CONNECTION));
         }
 
         ByteBuf challenge = response.content();

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker07.java

@@ -170,9 +170,9 @@ public class WebSocketClientHandshaker07 extends WebSocketClientHandshaker {
             throw new WebSocketHandshakeException("Invalid handshake response upgrade: " + upgrade);
         }
 
-        String connection = headers.get(Names.CONNECTION);
-        if (!Values.UPGRADE.equalsIgnoreCase(connection)) {
-            throw new WebSocketHandshakeException("Invalid handshake response connection: " + connection);
+        if (!headers.containsValue(Names.CONNECTION, Values.UPGRADE, true)) {
+            throw new WebSocketHandshakeException("Invalid handshake response connection: "
+                    + headers.get(Names.CONNECTION));
         }
 
         String accept = headers.get(Names.SEC_WEBSOCKET_ACCEPT);

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker08.java

@@ -170,9 +170,9 @@ public class WebSocketClientHandshaker08 extends WebSocketClientHandshaker {
             throw new WebSocketHandshakeException("Invalid handshake response upgrade: " + upgrade);
         }
 
-        String connection = headers.get(Names.CONNECTION);
-        if (!Values.UPGRADE.equalsIgnoreCase(connection)) {
-            throw new WebSocketHandshakeException("Invalid handshake response connection: " + connection);
+        if (!headers.containsValue(Names.CONNECTION, Values.UPGRADE, true)) {
+            throw new WebSocketHandshakeException("Invalid handshake response connection: "
+                    + headers.get(Names.CONNECTION));
         }
 
         String accept = headers.get(Names.SEC_WEBSOCKET_ACCEPT);

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker13.java

@@ -180,9 +180,9 @@ public class WebSocketClientHandshaker13 extends WebSocketClientHandshaker {
             throw new WebSocketHandshakeException("Invalid handshake response upgrade: " + upgrade);
         }
 
-        String connection = headers.get(Names.CONNECTION);
-        if (!Values.UPGRADE.equalsIgnoreCase(connection)) {
-            throw new WebSocketHandshakeException("Invalid handshake response connection: " + connection);
+        if (!headers.containsValue(Names.CONNECTION, Values.UPGRADE, true)) {
+            throw new WebSocketHandshakeException("Invalid handshake response connection: "
+                    + headers.get(Names.CONNECTION));
         }
 
         String accept = headers.get(Names.SEC_WEBSOCKET_ACCEPT);

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketServerHandshaker00.java

@@ -109,7 +109,7 @@ public class WebSocketServerHandshaker00 extends WebSocketServerHandshaker {
     protected FullHttpResponse newHandshakeResponse(FullHttpRequest req, HttpHeaders headers) {
 
         // Serve the WebSocket handshake request.
-        if (!Values.UPGRADE.equalsIgnoreCase(req.headers().get(CONNECTION))
+        if (!req.headers().containsValue(CONNECTION, Values.UPGRADE, true)
                 || !WEBSOCKET.equalsIgnoreCase(req.headers().get(Names.UPGRADE))) {
             throw new WebSocketHandshakeException("not a WebSocket handshake request: missing upgrade");
         }