diff options
Diffstat (limited to 'src/vendor/golang.org/x/net/quic/path.go')
| -rw-r--r-- | src/vendor/golang.org/x/net/quic/path.go | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/vendor/golang.org/x/net/quic/path.go b/src/vendor/golang.org/x/net/quic/path.go new file mode 100644 index 0000000000..5170562c74 --- /dev/null +++ b/src/vendor/golang.org/x/net/quic/path.go @@ -0,0 +1,87 @@ +// Copyright 2024 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package quic + +import "time" + +type pathState struct { + // Response to a peer's PATH_CHALLENGE. + // This is not a sentVal, because we don't resend lost PATH_RESPONSE frames. + // We only track the most recent PATH_CHALLENGE. + // If the peer sends a second PATH_CHALLENGE before we respond to the first, + // we'll drop the first response. + sendPathResponse pathResponseType + data pathChallengeData +} + +// pathChallengeData is data carried in a PATH_CHALLENGE or PATH_RESPONSE frame. +type pathChallengeData [64 / 8]byte + +type pathResponseType uint8 + +const ( + pathResponseNotNeeded = pathResponseType(iota) + pathResponseSmall // send PATH_RESPONSE, do not expand datagram + pathResponseExpanded // send PATH_RESPONSE, expand datagram to 1200 bytes +) + +func (c *Conn) handlePathChallenge(_ time.Time, dgram *datagram, data pathChallengeData) { + // A PATH_RESPONSE is sent in a datagram expanded to 1200 bytes, + // except when this would exceed the anti-amplification limit. + // + // Rather than maintaining anti-amplification state for each path + // we may be sending a PATH_RESPONSE on, follow the following heuristic: + // + // If we receive a PATH_CHALLENGE in an expanded datagram, + // respond with an expanded datagram. + // + // If we receive a PATH_CHALLENGE in a non-expanded datagram, + // then the peer is presumably blocked by its own anti-amplification limit. + // Respond with a non-expanded datagram. Receiving this PATH_RESPONSE + // will validate the path to the peer, remove its anti-amplification limit, + // and permit it to send a followup PATH_CHALLENGE in an expanded datagram. + // https://www.rfc-editor.org/rfc/rfc9000.html#section-8.2.1 + if len(dgram.b) >= smallestMaxDatagramSize { + c.path.sendPathResponse = pathResponseExpanded + } else { + c.path.sendPathResponse = pathResponseSmall + } + c.path.data = data +} + +func (c *Conn) handlePathResponse(now time.Time, _ pathChallengeData) { + // "If the content of a PATH_RESPONSE frame does not match the content of + // a PATH_CHALLENGE frame previously sent by the endpoint, + // the endpoint MAY generate a connection error of type PROTOCOL_VIOLATION." + // https://www.rfc-editor.org/rfc/rfc9000.html#section-19.18-4 + // + // We never send PATH_CHALLENGE frames. + c.abort(now, localTransportError{ + code: errProtocolViolation, + reason: "PATH_RESPONSE received when no PATH_CHALLENGE sent", + }) +} + +// appendPathFrames appends path validation related frames to the current packet. +// If the return value pad is true, then the packet should be padded to 1200 bytes. +func (c *Conn) appendPathFrames() (pad, ok bool) { + if c.path.sendPathResponse == pathResponseNotNeeded { + return pad, true + } + // We're required to send the PATH_RESPONSE on the path where the + // PATH_CHALLENGE was received (RFC 9000, Section 8.2.2). + // + // At the moment, we don't support path migration and reject packets if + // the peer changes its source address, so just sending the PATH_RESPONSE + // in a regular datagram is fine. + if !c.w.appendPathResponseFrame(c.path.data) { + return pad, false + } + if c.path.sendPathResponse == pathResponseExpanded { + pad = true + } + c.path.sendPathResponse = pathResponseNotNeeded + return pad, true +} |