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



____________________________________________________________________________________________________________

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

____________________________________________________________________________________________________________

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 pack-age package
       age 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 -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 pro-tocol. protocol.
              tocol.  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 com-mand. command.
              mand. 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://source -
       forge.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)