# purr-c

This is a pure C client for the
[PurritoBin](https://github.com/PurritoBin/PurritoBin) pastebin server, and uses
PurritoBin's author's instance in <https://bsd.ac> by default.

It was written as an exercise in learning network and crypto libraries, and uses
[BearSSL](https://www.bearssl.org/) for symmetric encryption (supported by
PurritoBin's online interface as well as its [suggested
clients](https://github.com/PurritoBin/PurritoBin/tree/master/clients)) and SSL
interaction with the server. For now, it also depends on
[s6-networking](http://skarnet.org/software/s6-networking/)'s `sbearssl` library
for certificate parsing.
[libbaseencode](https://github.com/paolostivanin/libbaseencode) has been
vendored in (can be found in `external/libbaseencode`), but has also gone
through some changes, namely removing null-byte checking from the base64
encoding function and adding an output length parameter to the base64 decoding
function.

The code has a few instances of `// TODO: remove hack` comments and the like,
which I hope to get to someday.

## Usage

Usage information can be viewed with `purr -h`.

## Build dependencies

The build dependencies are the ones listed above: BearSSL and s6-networking, as
well as GNU Make and a C compiler. This currently depends on Linux's
`getrandom(2)` function, but I plan on adding at least an `arc4random_buf(3)`
implementation.

## Acknowledgements

- Thomas Pornin for BearSSL
- Laurent Bercot for s6-networking
- epsilon-0 for PurritoBin (and the valuable help while I was testing this
   program)
- paolostivanin for libbaseencode