This introduces rate limits for the `ChannelReader` to limit DDoS attacks and
attempts to upload repositories that are larger than a node is will to permit.
The limiter sets the total number of bytes it is will to accept in a single
exchange, defaulting to 500MB. This means that initial fetches will prevent
large repositories, but is plenty for new packfile data to be sent in subsequent
fetch exchanges.
The limit can be configured within the node's config file, under the limits.
To avoid buffering large amounts of data in the process, we set the
worker channel size to `64`. Keep in mind that this is one
`ChannelEvent`, not one byte. `ChannelEvent::Data` can already contain
an arbitrary amount of data via its `Vec<u8>`, but in practice the
maximum is 8192, due to the use of `io::copy`.
We also remove an unused function, and move the flushing to the
`ChannelFlushWriter`.
This prevents potential memory leaks. We also ensure that sends fail
instead of blocking, in case the channels are full.
Additionally, we add some metrics to report on channel size.
From empirical testing, the `FETCH_TIMEOUT` can be set to a lower value of 3s.
For a repository that is about 300MiB, the process will successfully send all
packfile bytes and the references will be written.
The `--timeout` option is also used in the `git-upload-pack` process for good
measure.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
Wire up the `radicle-fetch` crate to the fetch logic in the
`radicle-node` worker.
Any required traits for storage, identity, tracking, and transport
used by `radicle-fetch`.
The worker adds a new module to run the `git upload-pack` process and
pipes the `stdout`/`stdin` to the respective channels.
The `Worker` type required adding a `FetchConfig` to easily allow the
configuration of fetches and passing the signer and tracking store
location through to the fetch `Handle`.
The channels code is adapted to have a new writer that always flushes
when a call to `write_all` is made. This is necessary since the
Gitoxide code never calls `flush`, and so it will hang since no data
is sent until `flush` is called.
Since `UserInfo` is used to set up a newly cloned repository, this
changed some of the SHA1 hashes output in the CLI test examples. It
was also necessary to update the CLI's clone code to be deterministic
in its output for tests.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
It's currently possible for a channel to be blocked forever while
waiting for data, if the remote peer keeps the connection alive.
This can occupy a worker indefinitely.
With these timeouts, we ensure that workers exit if there is no
activity after a certain amount of time.
To improve the reliability and flexibility of the protocol, we introduce
multiplexing over peer connections. This involves a new `Frame` type
that carries a stream-id and payload.
Three stream types are made available:
1. Control
2. Gossip
3. Git
This change brings the following improvements:
* Removed need to queue fetch requests
* Removed need to queue gossip messages
* Removed need for `Fetch` and `FetchOk` messages
* Service doesn't need to know about inbound fetches
* Removed one round-trip for fetch negotiation
* Removed special `done` git packet
* Removed session logic and state around Git/Fetch protocols
* Removed code around upgrading/downgrading transport
* Worker in responder mode is able to process any number of fetches
* Connections support any number of concurrent fetches
We had to introduce a few extra things however to make it all work:
* A `VarInt` type for variable-length integers, since we want the frames
to be lightweight.
* A custom "tunnel" implementation, since we couldn't use the existing
one anymore.
Overall the change removes more complexity than it adds, while improving
the protocol along the way.
Fintan Halpenny
cloudhead
Alexis Sellier