io.hawt.web.proxy

Class ProxyServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

io.hawt.web.proxy.ProxyServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

Direct Known Subclasses:

PodServlet, ServiceServlet

public class ProxyServlet
extends javax.servlet.http.HttpServlet

An HTTP reverse proxy/gateway servlet. It is designed to be extended for customization if desired. Most of the work is handled by Apache HttpClient.

There are alternatives to a servlet based proxy such as Apache mod_proxy if that is available to you. However this servlet is easily customizable by Java, secure-able by your web application's security (e.g. spring-security), portable across servlet engines, and is embeddable into another web application.

Inspiration: http://httpd.apache.org/docs/2.0/mod/mod_proxy.html

Original implementation at https://github.com/mitre/HTTP-Proxy-Servlet, released under ASL 2.0.

Author:

David Smiley dsmiley@mitre.org

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	acceptSelfSignedCerts
protected ProxyAllowlist	allowlist
protected static BitSet	asciiQueryChars
static String	DISABLE_PROXY
protected boolean	doForwardIP
protected boolean	doLog
protected boolean	enabled
static String	HAWTIO_DISABLE_PROXY
static String	HAWTIO_LOCAL_ADDRESS_PROBING
static String	HAWTIO_PROXY_ALLOWLIST
protected static org.apache.http.message.HeaderGroup	hopByHopHeaders These are the "hop-by-hop" headers that should not be copied.
static String	LOCAL_ADDRESS_PROBING
static String	P_FORWARDEDFOR A boolean parameter name to enable forwarding of the client IP
static String	P_LOG Deprecated. Use SLF4J Logger
static String	PROXY_ALLOWLIST
protected org.apache.http.impl.client.CloseableHttpClient	proxyClient

Constructor Summary

Constructors

Constructor and Description
ProxyServlet()

Method Summary

Modifier and Type	Method and Description
protected void	copyRequestHeaders(javax.servlet.http.HttpServletRequest servletRequest, org.apache.http.HttpRequest proxyRequest, URI targetUriObj) Copy request headers from the servlet client to the proxy request.
protected void	copyResponseEntity(org.apache.http.HttpResponse proxyResponse, javax.servlet.http.HttpServletResponse servletResponse) Copy response body data (the entity) from the proxy to the servlet client.
protected void	copyResponseHeaders(org.apache.http.HttpResponse proxyResponse, javax.servlet.http.HttpServletResponse servletResponse) Copy proxied response headers back to the servlet client.
void	destroy()
protected boolean	doResponseRedirectOrNotModifiedLogic(javax.servlet.http.HttpServletRequest servletRequest, javax.servlet.http.HttpServletResponse servletResponse, org.apache.http.HttpResponse proxyResponse, int statusCode, URI targetUriObj)
protected static CharSequence	encodeUriQuery(CharSequence in) Encodes characters in the query or fragment part of the URI.
String	getServletInfo()
void	init(javax.servlet.ServletConfig servletConfig)
protected ProxyAddress	parseProxyAddress(javax.servlet.http.HttpServletRequest servletRequest)
protected String	rewriteUrlFromResponse(javax.servlet.http.HttpServletRequest servletRequest, String theUrl, String targetUri) For a redirect response from the target server, this translates theUrl to redirect to and translates it to one the original client can use.
protected void	service(javax.servlet.http.HttpServletRequest servletRequest, javax.servlet.http.HttpServletResponse servletResponse)

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service

Methods inherited from class javax.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

P_LOG

@Deprecated
public static final String P_LOG

Deprecated. Use SLF4J Logger

A boolean parameter name to enable logging of input and target URLs to the servlet log.

See Also:

Constant Field Values

P_FORWARDEDFOR

public static final String P_FORWARDEDFOR

A boolean parameter name to enable forwarding of the client IP

See Also:

Constant Field Values

PROXY_ALLOWLIST

public static final String PROXY_ALLOWLIST

See Also:

Constant Field Values

LOCAL_ADDRESS_PROBING

public static final String LOCAL_ADDRESS_PROBING

See Also:

Constant Field Values

DISABLE_PROXY

public static final String DISABLE_PROXY

See Also:

Constant Field Values

HAWTIO_PROXY_ALLOWLIST

public static final String HAWTIO_PROXY_ALLOWLIST

See Also:

Constant Field Values

HAWTIO_LOCAL_ADDRESS_PROBING

public static final String HAWTIO_LOCAL_ADDRESS_PROBING

See Also:

Constant Field Values

HAWTIO_DISABLE_PROXY

public static final String HAWTIO_DISABLE_PROXY

See Also:

Constant Field Values

enabled

protected boolean enabled

doLog

protected boolean doLog

doForwardIP

protected boolean doForwardIP

acceptSelfSignedCerts

protected boolean acceptSelfSignedCerts

allowlist

protected ProxyAllowlist allowlist

proxyClient

protected org.apache.http.impl.client.CloseableHttpClient proxyClient

hopByHopHeaders

protected static final org.apache.http.message.HeaderGroup hopByHopHeaders

These are the "hop-by-hop" headers that should not be copied. http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html I use an HttpClient HeaderGroup class instead of Set because this approach does case insensitive lookup faster.

asciiQueryChars

protected static final BitSet asciiQueryChars

Constructor Detail

ProxyServlet

public ProxyServlet()

Method Detail

getServletInfo

public String getServletInfo()

Specified by:

getServletInfo in interface javax.servlet.Servlet

Overrides:

getServletInfo in class javax.servlet.GenericServlet

init

public void init(javax.servlet.ServletConfig servletConfig)
          throws javax.servlet.ServletException

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Servlet

Overrides:

destroy in class javax.servlet.GenericServlet

service

protected void service(javax.servlet.http.HttpServletRequest servletRequest,
                       javax.servlet.http.HttpServletResponse servletResponse)
                throws javax.servlet.ServletException,
                       IOException

Overrides:

service in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

IOException

parseProxyAddress

protected ProxyAddress parseProxyAddress(javax.servlet.http.HttpServletRequest servletRequest)

doResponseRedirectOrNotModifiedLogic

protected boolean doResponseRedirectOrNotModifiedLogic(javax.servlet.http.HttpServletRequest servletRequest,
                                                       javax.servlet.http.HttpServletResponse servletResponse,
                                                       org.apache.http.HttpResponse proxyResponse,
                                                       int statusCode,
                                                       URI targetUriObj)
                                                throws javax.servlet.ServletException,
                                                       IOException

Throws:

javax.servlet.ServletException

IOException

copyRequestHeaders

protected void copyRequestHeaders(javax.servlet.http.HttpServletRequest servletRequest,
                                  org.apache.http.HttpRequest proxyRequest,
                                  URI targetUriObj)

Copy request headers from the servlet client to the proxy request.

copyResponseHeaders

protected void copyResponseHeaders(org.apache.http.HttpResponse proxyResponse,
                                   javax.servlet.http.HttpServletResponse servletResponse)

Copy proxied response headers back to the servlet client.

copyResponseEntity

protected void copyResponseEntity(org.apache.http.HttpResponse proxyResponse,
                                  javax.servlet.http.HttpServletResponse servletResponse)
                           throws IOException

Copy response body data (the entity) from the proxy to the servlet client.

Throws:

IOException

rewriteUrlFromResponse

protected String rewriteUrlFromResponse(javax.servlet.http.HttpServletRequest servletRequest,
                                        String theUrl,
                                        String targetUri)

For a redirect response from the target server, this translates theUrl to redirect to and translates it to one the original client can use.

encodeUriQuery

protected static CharSequence encodeUriQuery(CharSequence in)

Encodes characters in the query or fragment part of the URI.

Unfortunately, an incoming URI sometimes has characters disallowed by the spec. HttpClient insists that the outgoing proxied request has a valid URI because it uses Java's URI. To be more forgiving, we must escape the problematic characters. See the URI class for the spec.

Parameters:

in - example: name=value&foo=bar#fragment