'\"
'\" Generated from file 'autoproxy\&.man' by tcllib/doctools with format 'nroff'
'\"
.TH "autoproxy" n 1\&.6 tcllib "HTTP protocol helper modules"
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.BS
.SH NAME
autoproxy \- Automatic HTTP proxy usage and authentication
.SH SYNOPSIS
package require \fBTcl  8\&.2\fR
.sp
package require \fBhttp  ?2\&.0?\fR
.sp
package require \fBautoproxy  ?1\&.6?\fR
.sp
\fB::autoproxy::init\fR
.sp
\fB::autoproxy::cget\fR \fI-option\fR
.sp
\fB::autoproxy::configure\fR ?-option \fIvalue\fR?
.sp
\fB::autoproxy::tls_connect\fR \fIargs\fR
.sp
\fB::autoproxy::tunnel_connect\fR \fIargs\fR
.sp
\fB::autoproxy::tls_socket\fR \fIargs\fR
.sp
.BE
.SH DESCRIPTION
.PP
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\&.
.PP
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\&.
.PP
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\&.
.SH "TLS SECURITY CONSIDERATIONS"
This package uses the \fBTLS\fR package to handle the security
for \fBhttps\fR urls and other socket connections\&.
.PP
Policy decisions like the set of protocols to support and what
ciphers to use are not the responsibility of \fBTLS\fR, nor of
this package itself however\&.
Such decisions are the responsibility of whichever application is
using the package, and are likely influenced by the set of servers
the application will talk to as well\&.
.PP
For example, in light of the recent
\fIPOODLE attack\fR [http://googleonlinesecurity\&.blogspot\&.co\&.uk/2014/10/this-poodle-bites-exploiting-ssl-30\&.html] discovered by Google many servers will disable support
for the SSLv3 protocol\&.
To handle this change the applications using \fBTLS\fR must be
patched, and not this package, nor \fBTLS\fR itself\&.
Such a patch may be as simple as generally activating \fBtls1\fR
support, as shown in the example below\&.
.CS


    package require tls
    tls::init -tls1 1 ;# forcibly activate support for the TLS1 protocol

    \&.\&.\&. your own application code \&.\&.\&.

.CE
.SH COMMANDS
.TP
\fB::autoproxy::init\fR
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\&.
.TP
\fB::autoproxy::cget\fR \fI-option\fR
Retrieve individual package configuration options\&. See \fBOPTIONS\fR\&.
.TP
\fB::autoproxy::configure\fR ?-option \fIvalue\fR?
Configure the autoproxy package\&. Calling \fBconfigure\fR with no
options will return a list of all option names and values\&.
See \fBOPTIONS\fR\&.
.TP
\fB::autoproxy::tls_connect\fR \fIargs\fR
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 \fBtls_socket\fR\&.
.sp
The \fIargs\fR list may contain any of the \fBtls\fR package options but
must end with the host and port as the last two items\&.
.TP
\fB::autoproxy::tunnel_connect\fR \fIargs\fR
Connect to a target host throught a proxy\&. This uses the same CONNECT
HTTP command as the \fBtls_connect\fR but does not promote the link
security once the connection is established\&.
.sp
The \fIargs\fR list may contain any of the \fBtls\fR package options but
must end with the host and port as the last two items\&.
.sp
Note that many proxy servers will permit CONNECT calls to a limited
set of ports - typically only port 443 (the secure HTTP port)\&.
.TP
\fB::autoproxy::tls_socket\fR \fIargs\fR
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\&.
.PP
.SH OPTIONS
.TP
\fB-host\fR hostname
.TP
\fB-proxy_host\fR hostname
Set the proxy hostname\&. This is normally set up by \fBinit\fR but may
be configured here as well\&.
.TP
\fB-port\fR number
.TP
\fB-proxy_port\fR number
Set the proxy port number\&. This is normally set up by \fBinit\fR\&.
e\&.g\&. \fBconfigure\fR \fB-port\fR \fI3128\fR
.TP
\fB-no_proxy\fR list
You may manipulate the \fBno_proxy\fR list that was setup by
\fBinit\fR\&. The value of this option is a tcl list of
strings that are matched against the http request host using the tcl
\fBstring match\fR command\&. Therefore glob patterns are permitted\&.
For instance, \fBconfigure\fR \fB-no_proxy\fR \fI*\&.localdomain\fR
.TP
\fB-authProc\fR procedure
This option may be used to set an application defined procedure to be
called when \fBconfigure\fR \fB-basic\fR 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\&.
.TP
\fB-basic\fR
Following options are for configuring the Basic authentication
scheme parameters\&. See \fBBasic Authentication\fR\&.
To unset the proxy authentication information retained from a previous
call of this function either "--" or no additional parameters can be
supplied\&. This will remove the existing authentication information\&.
.PP
.SH "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\&.
.PP
The following options exists for this scheme:
.TP
\fB-username\fR name
The username required to authenticate with the configured proxy\&.
.TP
\fB-password\fR password
The password required for the username specified\&.
.TP
\fB-realm\fR realm
This option is not used by this package but may be used in requesting
authentication details from the user\&.
.TP
\fB--\fR
The end-of-options indicator may be used alone to unset any
authentication details currently enabled\&.
.PP
.SH EXAMPLES
.PP
.CS


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

.CE
.CS


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/]

.CE
.SH REFERENCES
.IP [1]
Berners-Lee, T\&., Fielding R\&. and Frystyk, H\&.
"Hypertext Transfer Protocol -- HTTP/1\&.0",
RFC 1945, May 1996,
(\fIhttp://www\&.rfc-editor\&.org/rfc/rfc1945\&.txt\fR)
.IP [2]
Franks, J\&. et al\&.
"HTTP Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999
(\fIhttp://www\&.rfc-editor\&.org/rfc/rfc2617\&.txt\fR)
.PP
.SH 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\&.
.SH AUTHORS
Pat Thoyts
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIhttp :: autoproxy\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH "SEE ALSO"
http(n)
.SH KEYWORDS
authentication, http, proxy
.SH CATEGORY
Networking