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ignore management frames for a period after closing a connection #140

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merged 4 commits into from
Aug 31, 2018
Merged

ignore management frames for a period after closing a connection #140

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75253c8
added test to the case of receiving a ping frame after effectively cl…
HoneyryderChuck Aug 22, 2018
3f0cf83
added a timespan of 15 seconds under which one can still receive fram…
HoneyryderChuck Aug 22, 2018
445963b
changed spec description
HoneyryderChuck Aug 28, 2018
9224cee
testing also other control frames
HoneyryderChuck Aug 28, 2018
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5 changes: 5 additions & 0 deletions lib/http/2/connection.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,7 @@ def initialize(**settings)
@error = nil

@h2c_upgrade = nil
@closed_since = nil
end

def closed?
Expand Down Expand Up @@ -144,6 +145,7 @@ def goaway(error = :no_error, payload = nil)
send(type: :goaway, last_stream: last_stream,
error: error, payload: payload)
@state = :closed
@closed_since = Time.now
end

# Sends a WINDOW_UPDATE frame to the peer.
Expand Down Expand Up @@ -446,12 +448,15 @@ def connection_management(frame)
# the connection, although a new connection can be established
# for new streams.
@state = :closed
@closed_since = Time.now
emit(:goaway, frame[:last_stream], frame[:error], frame[:payload])
when :altsvc, :blocked
emit(frame[:type], frame)
else
connection_error
end
when :closed
connection_error if (Time.now - @closed_since) > 15
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Overall, what you wired up here makes sense. 👍

One question I have is.. Current logic will cover {settings, window_update, ping, goaway} connection management frames. What about other types of frames, do we need to do anything there? Per #139 (comment)...

After sending a GOAWAY frame, the sender can discard frames for
streams initiated by the receiver with identifiers higher than the
identified last stream. However, any frames that alter connection
state cannot be completely ignored. For instance, HEADERS,
PUSH_PROMISE, and CONTINUATION frames MUST be minimally processed to
ensure the state maintained for header compression is consistent (see
Section 4.3); similarly, DATA frames MUST be counted toward the
connection flow-control window. Failure to process these frames can
cause flow control or header compression state to become
unsynchronized.

Anything else / special we need to think about with respect to the above?

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I'd say it's already covered here, here or here.

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Fair enough. One corner case here is that we'll be ignoring all frames, irrespective of their ID being established before or after GOAWAY is emitted, but that's probably OK. If that surfaces as an issue, we can revisit.

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That is true, and I thought about that. One should throw protocol error for when a stream id is higher than the last stream id from the goaway frame. But I thought that was out of scope. Am I wrong?

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I think it's worth leaving a comment in the source, stating that we're not enforcing this behavior. I don't think we need to block this PR on implementing that though.

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after reading better, I think I advised for something which is not RFC-compliant. I think this PR covers everything necessary.

else
connection_error
end
Expand Down
7 changes: 7 additions & 0 deletions spec/connection_spec.rb
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Expand Up @@ -542,6 +542,13 @@
expect { @conn.new_stream }.to raise_error(ConnectionClosed)
end

it 'should not raise error when receiving connection management frames after closing' do
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"should not raise error when receiving connection management frames immediately after emitting goaway"?

Any merit in wiring up tests for one or two other types of frames?

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just added.

@conn.goaway
expect(@conn).to be_closed

expect { @conn << f.generate(PING.dup) }.not_to raise_error(ProtocolError)
end

it 'should process connection management frames after GOAWAY' do
@conn << f.generate(SETTINGS.dup)
@conn << f.generate(HEADERS.dup)
Expand Down