private static Pair<String, Integer> parseHostHeader(Headers headers) throws URISyntaxException {
        String host = headers.getFirst(HttpHeaderNames.HOST);
        if (host == null) {
            return new Pair<>(null, -1);
        }

        try {
            // attempt to use default URI parsing - this can fail when not strictly following RFC2396,
            // for example, having underscores in host names will fail parsing
            URI uri = new URI(/* scheme= */ null, host, /* path= */ null, /* query= */ null, /* fragment= */ null);
            if (uri.getHost() != null) {
                return new Pair<>(uri.getHost(), uri.getPort());
            }
        } catch (URISyntaxException e) {
            LOG.debug("URI parsing failed", e);
        }

        if (STRICT_HOST_HEADER_VALIDATION.get()) {
            throw new URISyntaxException(host, "Invalid host");
        }

        // fallback to using a colon split
        // valid IPv6 addresses would have been handled already so any colon is safely assumed a port separator
        String[] components = host.split(":", -1);
        if (components.length > 2) {
            // handle case with unbracketed IPv6 addresses
            return new Pair<>(null, -1);
        }

        String parsedHost = components[0];
        int parsedPort = -1;
        if (components.length > 1) {
            try {
                parsedPort = Integer.parseInt(components[1]);
            } catch (NumberFormatException e) {
                // ignore failing to parse port numbers and fallback to default port
                LOG.debug("Parsing of host port component failed", e);
            }
        }
        return new Pair<>(parsedHost, parsedPort);
    }
Attempt to parse the Host header from the collection of headers
and return the hostname and port components.

@return Hostname and Port pair.
        Hostname may be null. Port may be -1 when no valid port is found in the host header.
zuul-core/src/main/java/com/netflix/zuul/message/http/HttpRequestMessageImpl.java