Talk about nacos'DestroFilter

order

This paper mainly studies the ListroFilter of nacos.

CanDistro

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/web/CanDistro.java

@Retention(RetentionPolicy.RUNTIME)
public @interface CanDistro {
}
  • CanDistro is used to identify a method that needs to determine whether it should be redirected based on distro

DistroFilter

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/web/DistroFilter.java

public class DistroFilter implements Filter {

    private static final int PROXY_CONNECT_TIMEOUT = 2000;
    private static final int PROXY_READ_TIMEOUT = 2000;

    @Autowired
    private DistroMapper distroMapper;

    @Autowired
    private SwitchDomain switchDomain;

    @Autowired
    private FilterBase filterBase;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) servletRequest;
        HttpServletResponse resp = (HttpServletResponse) servletResponse;

        String urlString = req.getRequestURI();

        if (StringUtils.isNotBlank(req.getQueryString())) {
            urlString += "?" + req.getQueryString();
        }

        try {
            String path = new URI(req.getRequestURI()).getPath();
            String serviceName = req.getParameter(CommonParams.SERVICE_NAME);
            // For client under 0.8.0:
            if (StringUtils.isBlank(serviceName)) {
                serviceName = req.getParameter("dom");
            }
            Method method = filterBase.getMethod(req.getMethod(), path);

            if (method == null) {
                throw new NoSuchMethodException(req.getMethod() + " " + path);
            }

            String groupName = req.getParameter(CommonParams.GROUP_NAME);
            if (StringUtils.isBlank(groupName)) {
                groupName = Constants.DEFAULT_GROUP;
            }

            // use groupName@@serviceName as new service name:
            String groupedServiceName = serviceName;
            if (StringUtils.isNotBlank(serviceName) && !serviceName.contains(Constants.SERVICE_INFO_SPLITER)) {
                groupedServiceName = groupName + Constants.SERVICE_INFO_SPLITER + serviceName;
            }

            // proxy request to other server if necessary:
            if (method.isAnnotationPresent(CanDistro.class) && !distroMapper.responsible(groupedServiceName)) {

                String userAgent = req.getHeader("User-Agent");

                if (StringUtils.isNotBlank(userAgent) && userAgent.contains(UtilsAndCommons.NACOS_SERVER_HEADER)) {
                    // This request is sent from peer server, should not be redirected again:
                    Loggers.SRV_LOG.error("receive invalid redirect request from peer {}", req.getRemoteAddr());
                    resp.sendError(HttpServletResponse.SC_BAD_REQUEST,
                        "receive invalid redirect request from peer " + req.getRemoteAddr());
                    return;
                }

                List<String> headerList = new ArrayList<>(16);
                Enumeration<String> headers = req.getHeaderNames();
                while (headers.hasMoreElements()) {
                    String headerName = headers.nextElement();
                    headerList.add(headerName);
                    headerList.add(req.getHeader(headerName));
                }
                HttpClient.HttpResult result =
                    HttpClient.request("http://" + distroMapper.mapSrv(groupedServiceName) + urlString, headerList,
                        StringUtils.isBlank(req.getQueryString()) ? HttpClient.translateParameterMap(req.getParameterMap()) : new HashMap<>(2)
                        , PROXY_CONNECT_TIMEOUT, PROXY_READ_TIMEOUT, "UTF-8", req.getMethod());

                try {
                    resp.setCharacterEncoding("UTF-8");
                    resp.getWriter().write(result.content);
                    resp.setStatus(result.code);
                } catch (Exception ignore) {
                    Loggers.SRV_LOG.warn("[DISTRO-FILTER] request failed: " + distroMapper.mapSrv(groupedServiceName) + urlString);
                }
                return;
            }

            OverrideParameterRequestWrapper requestWrapper = OverrideParameterRequestWrapper.buildRequest(req);
            requestWrapper.addParameter(CommonParams.SERVICE_NAME, groupedServiceName);
            filterChain.doFilter(requestWrapper, resp);
        } catch (AccessControlException e) {
            resp.sendError(HttpServletResponse.SC_FORBIDDEN, "access denied: " + UtilsAndCommons.getAllExceptionMsg(e));
            return;
        } catch (NoSuchMethodException e) {
            resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, "no such api: " + e.getMessage());
            return;
        } catch (Exception e) {
            resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
                "Server failed," + UtilsAndCommons.getAllExceptionMsg(e));
            return;
        }

    }

    @Override
    public void destroy() {

    }
}
  • DistroFilter implements the servlet's Filter interface; its doFilter method reads serviceName, method, groupName, etc. from the servlet Request, and then determines whether the method labels CanDistro, and if distroMapper is not responsible for the service, it builds an http request and writes the result back to the filter; if no redirection is required, it continues to filter Chain. doFilter.

HttpClient.request

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/misc/HttpClient.java

public class HttpClient {
    private static final int TIME_OUT_MILLIS = 10000;
    private static final int CON_TIME_OUT_MILLIS = 5000;

    private static AsyncHttpClient asyncHttpClient;

    private static CloseableHttpClient postClient;

    //......

    public static HttpResult request(String url, List<String> headers, Map<String, String> paramValues, int connectTimeout, int readTimeout, String encoding, String method) {
        HttpURLConnection conn = null;
        try {
            String encodedContent = encodingParams(paramValues, encoding);
            url += (null == encodedContent) ? "" : ("?" + encodedContent);

            conn = (HttpURLConnection) new URL(url).openConnection();
            conn.setConnectTimeout(connectTimeout);
            conn.setReadTimeout(readTimeout);
            conn.setRequestMethod(method);

            conn.addRequestProperty("Client-Version", UtilsAndCommons.SERVER_VERSION);
            conn.addRequestProperty("User-Agent", UtilsAndCommons.SERVER_VERSION);
            setHeaders(conn, headers, encoding);
            conn.connect();

            return getResult(conn);
        } catch (Exception e) {
            Loggers.SRV_LOG.warn("Exception while request: {}, caused: {}", url, e);
            return new HttpResult(500, e.toString(), Collections.<String, String>emptyMap());
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }
    }

    private static HttpResult getResult(HttpURLConnection conn) throws IOException {
        int respCode = conn.getResponseCode();

        InputStream inputStream;
        if (HttpURLConnection.HTTP_OK == respCode) {
            inputStream = conn.getInputStream();
        } else {
            inputStream = conn.getErrorStream();
        }

        Map<String, String> respHeaders = new HashMap<String, String>(conn.getHeaderFields().size());
        for (Map.Entry<String, List<String>> entry : conn.getHeaderFields().entrySet()) {
            respHeaders.put(entry.getKey(), entry.getValue().get(0));
        }

        String gzipEncoding = "gzip";

        if (gzipEncoding.equals(respHeaders.get(HttpHeaders.CONTENT_ENCODING))) {
            inputStream = new GZIPInputStream(inputStream);
        }

        HttpResult result = new HttpResult(respCode, IOUtils.toString(inputStream, getCharset(conn)), respHeaders);
        inputStream.close();

        return result;
    }

    public static class HttpResult {
        final public int code;
        final public String content;
        final private Map<String, String> respHeaders;

        public HttpResult(int code, String content, Map<String, String> respHeaders) {
            this.code = code;
            this.content = content;
            this.respHeaders = respHeaders;
        }

        public String getHeader(String name) {
            return respHeaders.get(name);
        }
    }

    //......
}
  • The request method of HttpClient directly uses jdk's HttpURLConnection to make the request, and the return result is encapsulated as HttpResult, whose content is the body of the response.

Summary

DistroFilter implements the servlet's Filter interface; its doFilter method reads serviceName, method, groupName, etc. from the servlet Request, and then determines whether the method labels CanDistro, and if distroMapper is not responsible for the service, it builds an http request and writes the result back to the filter; if no redirection is required, it continues to filter Chain. doFilter.

doc

Keywords: Programming Java encoding JDK

Added by psd99 on Sat, 05 Oct 2019 14:12:38 +0300