feat: gateway support for tar.gz

[hacdias]

Built on top of #9029 and adds tar.gz format.

The official MIME Type for .gz is application/gzip. However, that makes it harder for us to distinguish what type of file it is. Therefore, I appended +gzip to the MIME Type of the TAR.

License: MIT
Signed-off-by: Henrique Dias hacdias@gmail.com

[Jorropo]

I don't like that such CPU hogging feature (file compression) is accessible on the gateway using the default config.
I think this would be an easly exploitable DOS vector. (create a file with the same hard to compress (/dev/urandom data) 1MiB leaves, repeated over and over, since this will keep reading the data from the data store it would be mostly network free and be focused on compressing, using lots of CPU)

I would like this more if it was dynamically scaling the compression level based on the CPU load.
But I feel like this is asking for a lot.

[Jorropo]

Also if someone cared about that, I think they are running a gateway seriously, and if they are, they are using a reverse proxy for TLS.

Can't they just configure the reverse proxy to handle compression ?

[hacdias]

That's a valid point @Jorropo! However, this gateway feature is also available via the public API (see also #7746), e.g.:

https://gateway.ipfs.io/api/v0/get?arg=QmYwAPJzv5CZsnA625s3Xf2nemtYgPpHdWEz79ojWnPbdG&compression=true&archive=true

I don't mind keeping #9029 only.

[Jorropo]

api/v0 😞

I don't really mind if it's there but I think it should be optional. (I guess that a comment for the spec PR.)

Also I think it should be generalised.
If this gets in, there is no reason to not compress cars too. (but that a comment for opening a new issue)

[lidel]

Let's park this until we agree on specs in ipfs/specs#288.
DoS concerns make this a good candidate for testing RFC process. 🥳

@hacdias when writing RFC for that PR, it would be useful to mention the concerns around .tar.gz variant in "Alternatives" and "Security" sections.

My hot take is that .tar from #9029 is fine, but .tar.gz from this PR comes with too much risk, but let's discuss that in ipfs/specs around RFC. 🙏

[lidel]

Closing as we decided to only do TAR (compression can happen at transport layer).
Specs in ipfs/specs#288, impl. in #9029 – lets continue there 👍