autoproxy(n)             HTTP protocol helper modules             autoproxy(n)



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NAME
       autoproxy - Automatic HTTP proxy usage and authentication

SYNOPSIS
       package require Tcl  8.2

       package require http  ?2.0?

       package require autoproxy  ?1.5.1?

       ::autoproxy::init

       ::autoproxy::cget -option

       ::autoproxy::configure ?-option value?

       ::autoproxy::tls_connect args

       ::autoproxy::tunnel_connect args

       ::autoproxy::tls_socket args

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DESCRIPTION
       This package attempts to automate the use of HTTP proxy servers in Tcl
       HTTP client code. It tries to initialize the web access settings from
       system standard locations and can be configured to negotiate
       authentication with the proxy if required.

       On Unix the standard for identifying the local HTTP proxy server seems
       to be to use the environment variable http_proxy or ftp_proxy and
       no_proxy to list those domains to be excluded from proxying.  On
       Windows we can retrieve the Internet Settings values from the registry
       to obtain pretty much the same information.  With this information we
       can setup a suitable filter procedure for the Tcl http package and
       arrange for automatic use of the proxy.

       There seem to be a number of ways that the http_proxy environment
       variable may be set up. Either a plain host:port or more commonly a URL
       and sometimes the URL may contain authentication parameters or these
       may be requested from the user or provided via http_proxy_user and
       http_proxy_pass. This package attempts to deal with all these schemes.
       It will do it's best to get the required parameters from the
       environment or registry and if it fails can be reconfigured.

COMMANDS
       ::autoproxy::init
              Initialize the autoproxy package from system resources. Under
              unix this means we look for environment variables. Under windows
              we look for the same environment variables but also look at the
              registry settings used by Internet Explorer.

       ::autoproxy::cget -option
              Retrieve individual package configuration options. See OPTIONS.

       ::autoproxy::configure ?-option value?
              Configure the autoproxy package. Calling configure with no
              options will return a list of all option names and values.  See
              OPTIONS.

       ::autoproxy::tls_connect args
              Connect to a secure socket through a proxy. HTTP proxy servers
              permit the use of the CONNECT HTTP command to open a link
              through the proxy to the target machine. This function hides the
              details. For use with the http package see tls_socket.

              The args list may contain any of the tls package options but
              must end with the host and port as the last two items.

       ::autoproxy::tunnel_connect args
              Connect to a target host throught a proxy. This uses the same
              CONNECT HTTP command as the tls_connect but does not promote the
              link security once the connection is established.

              The args list may contain any of the tls package options but
              must end with the host and port as the last two items.

              Note that many proxy servers will permit CONNECT calls to a
              limited set of ports - typically only port 443 (the secure HTTP
              port).

       ::autoproxy::tls_socket args
              This function is to be used to register a proxy-aware secure
              socket handler for the https protocol. It may only be used with
              the Tcl http package and should be registered using the
              http::register command (see the examples below). The job of
              actually creating the tunnelled connection is done by the
              tls_connect command and this may be used when not registering
              with the http package.

OPTIONS
       -host hostname

       -proxy_host hostname
              Set the proxy hostname. This is normally set up by init but may
              be configured here as well.

       -port number

       -proxy_port number
              Set the proxy port number. This is normally set up by init.
              e.g. configure -port 3128

       -no_proxy list
              You may manipulate the no_proxy list that was setup by init. The
              value of this option is a tcl list of strings that are matched
              against the http request host using the tcl string match
              command. Therefore glob patterns are permitted.  For instance,
              configure -no_proxy *.localdomain

       -authProc procedure
              This option may be used to set an application defined procedure
              to be called when configure -basic is called with either no or
              insufficient authentication details. This can be used to present
              a dialog to the user to request the additional information.

       -basic Following options are for configuring the Basic authentication
              scheme parameters. See Basic Authentication.

BASIC AUTHENTICATION
       Basic is the simplest and most commonly use HTTP proxy authentication
       scheme. It is described in (1 section 11) and also in (2). It offers no
       privacy whatsoever and its use should be discouraged in favour of more
       secure alternatives like Digest. To perform Basic authentication the
       client base64 encodes the username and plaintext password separated by
       a colon. This encoded text is prefixed with the word "Basic" and a
       space.

       The following options exists for this scheme:

       -username name
              The username required to authenticate with the configured proxy.

       -password password
              The password required for the username specified.

       -realm realm
              This option is not used.

EXAMPLES
              package require autoproxy
              autoproxy::init
              autoproxy::configure -basic -username ME -password SEKRET
              set tok [http::geturl http://wiki.tcl.tk/]
              http::data $tok



              package require http
              package require tls
              package require autoproxy
              autoproxy::init
              http::register https 443 autoproxy::tls_socket
              set tok [http::geturl https://www.example.com/]


REFERENCES
       [1]    Berners-Lee, T., Fielding R. and Frystyk, H.  "Hypertext
              Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996,
              (http://www.rfc-editor.org/rfc/rfc1945.txt)

       [2]    Franks, J. et al.  "HTTP Authentication: Basic and Digest Access
              Authentication", RFC 2617, June 1999 (http://www.rfc-
              editor.org/rfc/rfc2617.txt)

BUGS
       At this time only Basic authentication (1) (2) is supported. It is
       planned to add support for Digest (2) and NTLM in the future.

AUTHORS
       Pat Thoyts

BUGS, IDEAS, FEEDBACK
       This document, and the package it describes, will undoubtedly contain
       bugs and other problems.  Please report such in the category http ::
       autoproxy of the Tcllib SF Trackers
       [http://sourceforge.net/tracker/?group_id=12883].  Please also report
       any ideas for enhancements you may have for either package and/or
       documentation.

SEE ALSO
       http(n)

KEYWORDS
       authentication, http, proxy

CATEGORY
       Networking



http                                 1.5.1                        autoproxy(n)
