.. _protocol_client_http_custom_headers:

###################
Http Custom Headers
###################

Chained Final Info Headers
==========================

These headers are neither reset nor appended by intermediate proxies. This
means their values always come from the proxy closest to the final upstream.

X-VEY-Upstream-Id
-----------------

If this header is present, the response came from a remote peer. The value is
the corresponding *server_id*.

If this header appears in an error response, it indicates that the response was
generated by the server after the one identified by the same *server_id*. That
may be either the final upstream server or another proxy in the chain.

This header is controlled by http_proxy server option
:ref:`http_forward_mark_upstream <config_server_http_proxy_http_forward_mark_upstream>`.

X-VEY-Upstream-Addr
-------------------

If present, this header contains the remote address that the outermost proxy in
the chain is trying to connect to.

This header is controlled by http_proxy server option
:ref:`echo_chained_info <config_server_http_proxy_echo_chained_info>`.

X-VEY-Outgoing-Ip
-----------------

If present, this header contains the local bind IP used by the outermost proxy
in the chain when connecting to the remote peer.

This header is controlled by http_proxy server option
:ref:`echo_chained_info <config_server_http_proxy_echo_chained_info>`.

Local Info Headers
==================

Each proxy in the chain appends its own value. Values closer to the upstream
appear first.

X-VEY-Remote-Connection-Info
----------------------------

The value format:

::

    <server_id>[; bind=<bind_ip>][; remote=<remote_addr>][; local=<local_addr>][; expire=<expire_rfc3339>]

* bind_ip

  The IP address selected for binding before the connection is established.

* remote_addr

  The remote socket address selected before the connection is established.

* local_addr

  The local socket address actually bound after the connection is established.

* expire_rfc3339

  The expiration time of the remote peer. This field is not set when the remote
  side is the final upstream target.

This header is controlled by http_proxy server option :ref:`server_id <config_server_http_proxy_server_id>`.

X-VEY-Dynamic-Egress-Info
-------------------------

The value format:

::

    <server_id>[; isp=<isp>][; ip=<ip>][; area=<area>]

* isp

  ISP information for the egress IP address.

* ip

  The externally visible egress IP address.

* area

  Geographic area associated with the egress IP address. The format is a
  ``/``-separated string, for example ``中国/山东/济南``.