This, uh, grew into something far bigger than expected, but it turns out, all of it was needed to eventually support this correctly.
- Adds configuration to client and server to set [SETTINGS_MAX_HEADER_LIST_SIZE](http://httpwg.org/specs/rfc7540.html#SETTINGS_MAX_HEADER_LIST_SIZE)
- If not set, a "sane default" of 16 MB is used (taken from golang's http2)
- Decoding header blocks now happens as they are received, instead of buffering up possibly forever until the last continuation frame is parsed.
- As each field is decoded, it's undecoded size is added to the total. Whenever a header block goes over the maximum size, the `frame` will be marked as such.
- Whenever a header block is deemed over max limit, decoding will still continue, but new fields will not be appended to `HeaderMap`. This is also can save wasted hashing.
- To protect against enormous string literals, such that they span multiple continuation frames, a check is made that the combined encoded bytes is less than the max allowed size. While technically not exactly what the spec suggests (counting decoded size instead), this should hopefully only happen when someone is indeed malicious. If found, a `GOAWAY` of `COMPRESSION_ERROR` is sent, and the connection shut down.
- After an oversize header block frame is finished decoding, the streams state machine will notice it is oversize, and handle that.
- If the local peer is a server, a 431 response is sent, as suggested by the spec.
- A `REFUSED_STREAM` reset is sent, since we cannot actually give the stream to the user.
- In order to be able to send both the 431 headers frame, and a reset frame afterwards, the scheduled `Canceled` machinery was made more general to a `Scheduled(Reason)` state instead.
Closes#18Closes#191
- Adds `max_frame_size` to client and server builders
- Pushes max_frame_size into Codec
- Detects when the Codec triggers an error from a frame too big
- Sends a GOAWAY when FRAME_SIZE_ERROR is encountered reading a frame
This change adds a .rustfmt.toml that includes ALL supported settings,
12 of which we have overridden to attempt to cater to our own
proclivities.
rustfmt is checked in the rust-nightly CI job.
This patch does a bunch of refactoring, mostly around error types, but it also
paves the way to allow `Codec` to be used standalone.
* `Codec` (and `FramedRead` / `FramedWrite`) is broken out into a codec module.
* An h2-codec crate is created that re-exports the frame and codec modules.
* New error types are introduced in the internals:
* `RecvError` represents errors caused by trying to receive a frame.
* `SendError` represents errors caused by trying to send a frame.
* `UserError` is an enum of potential errors caused by invalid usage
by the user of the lib.
* `ProtoError` is either a `Reason` or an `io::Error`. However it doesn't
specify connection or stream level.
* `h2::Error` is an opaque error type and is the only error type exposed
by the public API (used to be `ConnectionError`).
There are misc code changes to enable this as well. The biggest is a new "sink"
API for `Codec`. It provides buffer which queues up a frame followed by flush
which writes everything that is queued. This departs from the `Sink` trait in
order to provide more accurate error values. For example, buffer can never fail
(but it will panic if `poll_ready` is not called first).
