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@documentencoding UTF-8
@settitle tofuproxy

@copying
Copyright @copyright{} 2021 @email{stargrave@@stargrave.org, Sergey Matveev}
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@node Top
@top tofuproxy

@itemize

@item I am tired that various HTTPS clients (like browsers and feed
aggregators) use various TLS libraries with different features. NSS,
GnuTLS, OpenSSL... All of them sucks, comparing to Go's @code{crypto/tls}.

@item I tired that everyone provides very limited certificates trust
management capabilities, like either certificate or SPKI
@url{https://en.wikipedia.org/wiki/Certificate_pinning, pinning} with
@url{https://en.wikipedia.org/wiki/Trust_on_first_use, TOFU}. Even my
beloved @url{https://en.wikipedia.org/wiki/Xombrero, Xombrero} browser
still pins only the whole certificate, but its public key would be much
more sufficient and convenient to work with.

@item I am tired that many clients provides very few information about
certificates and connections at all.

@item I hate that hardly anyone can control (no automatic silent
transparent following) HTTP redirections. Although Firefox had proper
extensions for that.

@item I am sick of tiny control on URLs. The best you can is to use some
kind of @url{https://en.wikipedia.org/wiki/Privoxy, Privoxy}, but it is
not friendly with TLS connections, obviously.

@item Hardly anyone does
@url{https://en.wikipedia.org/wiki/DNS-based_Authentication_of_Named_Entities, DANE}
checks.

@item And there is insanity of downloading fonts.
Why the hell people just do not send PostScript documents instead!?

@item And wonderful @url{http://jpegxl.info/, JPEG XL} image format is
not supported by most browsers. Even pretty old
@url{https://developers.google.com/speed/webp, WebP} is not supported
everywhere. @url{https://aomediacodec.github.io/av1-avif/, AVIF} would
be useful too.

@end itemize

That is why I wrote @command{tofuproxy} -- pure Go HTTP proxy, MitMing
all HTTPS connections on the fly. It is written for my personal needs
exclusively, so many features are just directly hard-coded, instead of
creating some kind of complex configuration framework.

@itemize

@item Effective responses proxying, without storing them in the memory first.

@item TLS connection between client and @command{tofuproxy} has the
    proper hostname set in ephemeral on-the-fly generated certificate.

@item @code{HEAD} method for Xombrero is forbidden, as it loves it too much.

@item @code{www.reddit.com} is redirected to @code{old.reddit.com}.

@item @url{https://habr.com/ru/all/, Хабр}'s resolution reduced images
    are redirected to their full size variants.

@item Various spying domains (advertisement, tracking counters) are denied.

@item Web fonts downloads are forbidden.

@item Permanent HTTP redirects are replaced with HTML page with the link.

@item Temporary HTTP redirects are replaced with HTML too, if it is
    neither @url{https://newsboat.org/, Newsboat} nor image paths.

@item WebP images, if it is not Xombrero, is transcoded to PNG.

@item JPEG XL and AVIF images are transparently transcoded to PNG too.

@item Default Go's checks are applied to all certificates. If they pass,
    then certificate chain is saved on the disk. Future connections are
    compared against it, warning you about SPKI change and waiting for
    your decision either to accept new chain (possibly once per
    session), or reject it.

@item Even when native Go's checks are failed, you can still make a
    decision to forcefully trust the domain.

@item Optionally DANE-EE check is also made for each domain you visit.

@item TLS session resumption and keep-alives are also supported.

@item And Go itself tries also to act as a
@url{https://http2.github.io/, HTTP/2} client too.

@end itemize

@include usage.texi

@node TODO
@unnumbered TODO

What I am planning possibly to do? Just brainstorming:

@itemize

@item HTTP authorization dialog.

@item TLS client certificates usage capability.

@end itemize