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 -optionname

       ::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 envi-
       ronment 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 -optionname
	      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-edi-
	      tor.org/rfc/rfc1945.txt)

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