Class ForwardedRequest

java.lang.Object

org.apache.hc.core5.http.protocol.ForwardedRequest

All Implemented Interfaces:

HttpRequestInterceptor

@Contract(threading=IMMUTABLE)
public class ForwardedRequest
extends Object
implements HttpRequestInterceptor

This request interceptor can be used by an HTTP proxy or an intermediary to add a Forwarded header to outgoing request messages. The Forwarded header is used to capture information about the intermediate nodes that a request has passed through. This information can be useful for security purposes or for debugging purposes.

The Forwarded header consists of a list of key-value pairs separated by semicolons. The keys that can be used in the Forwarded header include "host", "port", "proto", "for", and "by". The host key is used to specify the host name or IP address of the request authority. The port key is used to specify the port number of the request authority. The proto key is used to specify the protocol version of the request. The for key is used to specify the IP address of the client making the request. The by key is used to specify the IP address of the node adding the Forwarded header.

When multiple proxy servers are involved in forwarding a request, each proxy can add its own Forwarded header to the request. This allows for the capture of information about each intermediate node that the request passes through.

The ForwardedRequest class adds the Forwarded header to the request by implementing the process() method of the HttpRequestInterceptor interface. The method retrieves the ProtocolVersion and URIAuthority from the HttpContext. The ProtocolVersion is used to determine the proto key value and the URIAuthority is used to determine the host and port key values. The method also retrieves the EndpointDetails from the HttpContext, if it exists. The EndpointDetails is used to determine the by and for key values. If a Forwarded header already exists in the request, the existing header is not overwritten; instead, the new header value is appended to the existing header value, with a comma separator.

Since:

5.3

Field Summary

Fields

Modifier and Type	Field	Description
private static final String	FORWARDED_HEADER_NAME	The name of the header to set in the HTTP request.
static final HttpRequestInterceptor	INSTANCE	Singleton instance.

Constructor Summary

Constructors

Constructor	Description
ForwardedRequest()

Method Summary

Modifier and Type	Method	Description
void	process(HttpRequest request, EntityDetails entity, HttpContext localContext)	The process method adds a Forwarded header to an HTTP request containing information about the intermediate nodes that the request has passed through.

Methods inherited from class Object

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

Field Details

FORWARDED_HEADER_NAME

private static final String FORWARDED_HEADER_NAME

The name of the header to set in the HTTP request.

See Also:

• Constant Field Values

INSTANCE

public static final HttpRequestInterceptor INSTANCE

Singleton instance.

Constructor Details

ForwardedRequest

public ForwardedRequest()

Method Details

process

public void process(HttpRequest request,
 EntityDetails entity,
 HttpContext localContext)
             throws HttpException,
IOException

The process method adds a Forwarded header to an HTTP request containing information about the intermediate nodes that the request has passed through. If a Forwarded header already exists in the request, the new header value is appended to the existing header value, with a comma separator.

The method retrieves the ProtocolVersion and URIAuthority from the HttpContext. The ProtocolVersion is used to determine the proto key value and the URIAuthority is used to determine the host and port key values. The method also retrieves the EndpointDetails from the HttpContext, if it exists. The EndpointDetails is used to determine the by key value.

Specified by:

process in interface HttpRequestInterceptor

Parameters:

request - the HTTP request to which the Forwarded header is to be added (not null)

entity - the entity details of the request (can be null)

localContext - the HTTP context in which the request is being executed (not null)

Throws:

HttpException - if there is an error processing the request

IOException - if an IO error occurs while processing the request

ProtocolException - if the request authority is not specified