# Telescope

Telescope is a Emacs/w3m-inspired browser for the "small internet"
that supports Gemini, Gopher and Finger.

Features:

 - tabs
 - bookmarks
 - privsep
 - minibuffer live narrowing
 - multiple protocols support
 - fully customizable

There are still various things missing or, if you prefer, various
things that you can help develop :)

 - subscriptions
 - tofu oob verification
 - client certificates
 - add other GUIs: at the moment it uses only ncurses, but telescope
   shouldn't be restricted to TTYs only!

[![asciicast](https://asciinema.org/a/426862.svg)](https://asciinema.org/a/426862)


## Why yet another browser?

One of the great virtues of Gemini is its simplicity.  It means that
writing browsers or server is easy and thus a plethora of those
exists.  I myself routinely switch between a couple of them, depending
on my mood.

More browsers brings more stability as it became more difficult to
change the protocol, too.

However, Telescope was ultimately written for fun, on a whim, just to
play with ncurses, libtls, libevent and the macros from `sys/queue.h`,
but I'd like to finish it into a complete Gemini browser.


## Goals

 - Fun: hacking on Telescope should be fun.
 - Clean: write readable and clean code mostly following the style(9)
   guideline.  Don't become a kitchen sink.
 - Secure: write secure code with privilege separation to mitigate the
   security risks of possible bugs.
 - Fast: it features a modern, fast, event-based asynchronous I/O
   model.
 - Cooperation: re-use existing conventions to allow inter-operations
   and easy migrations from/to other clients.


## TOFU

Telescope aims to use the "Trust, but Verify (where appropriate)"
approach outlined here:
[gemini://thfr.info/gemini/modified-trust-verify.gmi](gemini://thfr.info/gemini/modified-trust-verify.gmi).

The idea is to define three level of verification for a certificate:

 - **untrusted**: the server fingerprint does NOT match the stored
   value
 - **trusted**: the server fingerprint matches the stored one
 - **verified**: the fingerprint matches and has been verified
   out-of-band by the client.

Most of the time, the `trusted` level is enough, but where is
appropriate users should be able to verify out-of-band the
certificate.

At the moment there is no UI for oob-verification though.


## Building

Telescope depends on ncursesw, libtls (from either LibreSSL or
libretls), libevent (either v1 or v2) and pkg-config.
[libgrapheme][libgrapheme] is an optional dependency: there's a
bundled copy but it's reccomended to install it if available. When
building from a git checkout, yacc (or bison) is also needed.

To build from a release tarball just execute:

	$ ./configure
	$ make
	$ sudo make install

The configure script has optional support for building with libraries
provided by your distribution instead of using the bundled versions:

 - `--with-libbsd`: link with [libbsd][libbsd]
 - `--with-libimsg`: link with the [imsg-compat][imsg-compat] library

If you want to build from the git checkout, something that's
discouraged for users that don't intend to hack on telescope

	$ ./autogen.sh
	$ ./configure
	$ make
	$ sudo make install	# eventually

Please keep in mind that the main branch, from time to time, may be
accidentally broken on some platforms.  Telescope is developed
primarily on OpenBSD/amd64 and commits on the main branch don't get
always tested in other OSes.  Before tagging a release however, a
comprehensive testing on various platforms is done to ensure
everything is working as intended.

[libbsd]:	https://libbsd.freedesktop.org
[imsg-compat]:	https://github.com/bsd-ac/imsg-compat
[libgrapheme]:	https://libs.suckless.org/libgrapheme/


## Contributing

Any form of contribution is appreciated, not only patches or bug
reports: feel free to open an issue or send an email to
`telescope@omarpolo.com`.

If you have a sample configuration, custom theme, a script or anything
that could be helpful to others, consider adding it to the `contrib`
directory.


## User files

Telescope stores user files according to the [XDG Base Directory
Specification][xdg] by default.  The usage and contents of these files
are described in [the man page](telescope.1), under "FILES".

Only one instance of Telescope can be running at time per user.


## License

Telescope is distributed under a BSD-style licence.  The main code is
under the ISC but for files under `compat/` it varies.

`data/emoji.txt` is copyright © 1991-2021 Unicode, Inc. and
distributed under the [UNICODE, Inc license
agreement][unicode-license].


[unicode-license]: https://www.unicode.org/license.html
[xdg]: https://specifications.freedesktop.org/basedir-spec/latest/