Expose containsValue method on the MultiMap interface

[machine424]

Describe the feature

The containsValue(name, value, ...) method in HeadersMultiMap is meant to check the existence of a value in a multi values key/header.

I'll be useful to expose this method into the MultiMap interface: check for a sub-value (for now, only the contains method is defined, which only checks for value equality)

This will help with checks on the Connection header for websocket upgrades e.g. given that Firefox sends Connection: keep-alive, Upgrade instead of Connection: Upgrade. It would prevent re-implementingthat in different places, for example:

• vertx-web: https://github.com/vert-x3/vertx-web/blob/9e3a783b1d1a731055e9049078b1b1494ece9c15/vertx-web/src/main/java/io/vertx/ext/web/impl/Utils.java#L235-L255
• vertx:

  vert.x/src/main/java/io/vertx/core/http/impl/Http1xServerConnection.java

  Lines 359 to 365 in 244b910

  	private WebSocketServerHandshaker createHandshaker(Http1xServerRequest request) throws WebSocketHandshakeException {
  	// As a fun part, Firefox 6.0.2 supports Websockets protocol '7'. But,
  	// it doesn't send a normal 'Connection: Upgrade' header. Instead it
  	// sends: 'Connection: keep-alive, Upgrade'. Brilliant.
  	String connectionHeader = request.getHeader(io.vertx.core.http.HttpHeaders.CONNECTION);
  	if (connectionHeader == null || !connectionHeader.toLowerCase().contains("upgrade")) {
  	request.response()

• vertx:

  vert.x/src/main/java/io/vertx/core/http/impl/Http1xUpgradeToH2CHandler.java

  Lines 52 to 75 in 244b910

  	public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
  	if (msg instanceof HttpRequest) {
  	HttpRequest request = (HttpRequest) msg;
  	if (request.headers().contains(io.vertx.core.http.HttpHeaders.UPGRADE, Http2CodecUtil.HTTP_UPGRADE_PROTOCOL_NAME, true)) {
  	String connection = request.headers().get(io.vertx.core.http.HttpHeaders.CONNECTION);
  	int found = 0;
  	if (connection != null && connection.length() > 0) {
  	StringBuilder buff = new StringBuilder();
  	int pos = 0;
  	int len = connection.length();
  	while (pos < len) {
  	char c = connection.charAt(pos++);
  	if (c != ' ' && c != ',') {
  	buff.append(Character.toLowerCase(c));
  	}
  	if (c == ',' || pos == len) {
  	if (buff.indexOf("upgrade") == 0 && buff.length() == 7) {
  	found |= 1;
  	} else if (buff.indexOf("http2-settings") == 0 && buff.length() == 14) {
  	found |= 2;
  	}
  	buff.setLength(0);
  	}
  	}

  (maybe allowcontainsValue to look for different values on the same loop.)
• vertx:

  vert.x/src/main/java/io/vertx/core/http/impl/HttpUtils.java

  Lines 971 to 974 in 244b910

  	static boolean isConnectOrUpgrade(io.vertx.core.http.HttpMethod method, MultiMap headers) {
  	return method == io.vertx.core.http.HttpMethod.CONNECT || (method == io.vertx.core.http.HttpMethod.GET && headers.contains(io.vertx.core.http.HttpHeaders.CONNECTION, io.vertx.core.http.HttpHeaders.UPGRADE, true));
  	}

• vertx-http-proxy: https://github.com/eclipse-vertx/vertx-http-proxy/blob/7a139fc609904675df5c9cb68b4d5c253b899648/src/main/java/io/vertx/httpproxy/impl/ReverseProxy.java#L85-L90 (see: )
• It'll be useful for other consumers as well.