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 -option
::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 -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.
-
-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 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.
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/]
-
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)
-
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
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)
http, proxy, authentication