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







autoproxy - Automatic HTTP proxy usage and authentication








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












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.









  
::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.











  

  

  

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

  

  

  

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

  

  
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

  

  
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.

  

  
Following options are for configuring the Basic authentication scheme
      parameters. See 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:



  

  
The username required to authenticate with the configured proxy.

  

  
The password required for the username specified.

  

  
This option is not used.










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/]










  
[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)










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








Pat Thoyts








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.








http(n)








authentication, http, proxy








Networking







  

    1.5.1
    http