map $ssl_preread_server_name $sni_name {
    hostnames;
    www.vk.com      xray;
    duckdns.org           www;
    *.duckdns.org         www;
    default              xray;
}

upstream xray {
    server 46.29.236.6:443;
}

upstream www {
    server 127.0.0.1:7443;
}

server {
    listen          443;
    proxy_pass      $sni_name;
    ssl_preread     on;
}