Proxy support

[sameerhr84]

Problem or use case

Most of the use cases we have requires proxy support for the MQTT client. Do we have this feature

Preferred solution or suggestions

can MqttChannelInitializer have the ability to inject proxy handler as part of initMqtt(...) methods

adding proxy to pipeline:

private void addProxyHandlerIfNeeded(ChannelPipeline pipeline, HttpProxyConfig httpProxyConfig,
        @Nullable String passwordOverride) throws Exception {
    String proxyHost = httpProxyConfig.host();
    if (proxyHost.isEmpty()) {
        return;
    }
    int proxyPort = MoreObjects.firstNonNull(httpProxyConfig.port(), 80);
    SocketAddress proxyAddress = new InetSocketAddress(proxyHost, proxyPort);
    String username = httpProxyConfig.username();
    if (username.isEmpty()) {
        pipeline.addLast(new HttpProxyHandler(proxyAddress));
    } else {
        String password = getPassword(httpProxyConfig, passwordOverride);
        pipeline.addLast(new HttpProxyHandler(proxyAddress, username, password));
    }
}

Proxy handler similar to below :

public final ProxyHandler newProxyHandler() {
	InetSocketAddress proxyAddr = this.address.get();
	String username = this.username;
	String password = Objects.nonNull(username) && Objects.nonNull(this.password) ?
			this.password.apply(username) : null;

	switch (this.type) {
		case HTTP:
			return Objects.nonNull(username) && Objects.nonNull(password) ?
					new HttpProxyHandler(proxyAddr, username, password) :
					new HttpProxyHandler(proxyAddr);
		case SOCKS4:
			return Objects.nonNull(username) ? new Socks4ProxyHandler(proxyAddr, username) :
					new Socks4ProxyHandler(proxyAddr);
		case SOCKS5:
			return Objects.nonNull(username) && Objects.nonNull(password) ?
					new Socks5ProxyHandler(proxyAddr, username, password) :
					new Socks5ProxyHandler(proxyAddr);
	}
	throw new IllegalArgumentException("Proxy type unsupported : " + this.type);
}

[SgtSilvio]

@sameerhr84 proxy support is now part of version 1.2.0

[sameerhr84]

Thank you @SgtSilvio for helping with this feature request.