Telescope

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

In features some expected stuff (tabs, bookmarks, history, client
certificates, …) with an UI that’s very much Emacs and w3m inspired,
and a privsep design.

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

other “smol internet” protocols
subscriptions
TOFU out-of-band verification and/or DANE
multiple UIs: at the moment it uses only ncurses, but telescope
shouldn’t be restricted to TTYs only!

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 means more choice for the users, and more stability for
the protocol too.

However, Telescope was ultimately written for fun, on a whim, just to
play with ncurses, libtls, async I/O 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 OpenBSD
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: reuse 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.

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 out-of-band verification though.

Building

Telescope depends on ncursesw, libtls or libretls, yacc/bison and
pkg-config. libgrapheme is an optional dependency:
there’s a bundled copy but it’s recommended to install it with a package
manager if available.

To build execute:

$ ./autogen.sh        # only from git checkouts
$ ./configure
$ make
$ sudo make install    # eventually

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
--with-libimsg: link with the imsg-compat library

The default-editor can be changed at build-time with the following option:

--with-default-editor: defaults to ed(1)

This is useful for distributions such as Debian, which prefers
sensible-editor(1) as a wrapper.

This feature is mostly useful with the mini-edit-external command in
telescope.

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.

Consider also joining the official
irc channel,
#telescope on libera.chat!

User files

Telescope stores user files according to the XDG Base Directory
Specification by default. The usage and contents of these files
are described in the man page, under “FILES”.

At the moment, 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
either under the ISC or is Public Domain, but some files under compat/
are 3-Clause BSD or MIT. See the first few lines of every file or
about:license inside telescope for the copyright information.