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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package dtls
/*
DTLS messages are grouped into a series of message flights, according
to the diagrams below. Although each flight of messages may consist
of a number of messages, they should be viewed as monolithic for the
purpose of timeout and retransmission.
https://tools.ietf.org/html/rfc4347#section-4.2.4
Message flights for full handshake:
Client Server
------ ------
Waiting Flight 0
ClientHello --------> Flight 1
<------- HelloVerifyRequest Flight 2
ClientHello --------> Flight 3
ServerHello \
Certificate* \
ServerKeyExchange* Flight 4
CertificateRequest* /
<-------- ServerHelloDone /
Certificate* \
ClientKeyExchange \
CertificateVerify* Flight 5
[ChangeCipherSpec] /
Finished --------> /
[ChangeCipherSpec] \ Flight 6
<-------- Finished /
Message flights for session-resuming handshake (no cookie exchange):
Client Server
------ ------
Waiting Flight 0
ClientHello --------> Flight 1
ServerHello \
[ChangeCipherSpec] Flight 4b
<-------- Finished /
[ChangeCipherSpec] \ Flight 5b
Finished --------> /
[ChangeCipherSpec] \ Flight 6
<-------- Finished /
*/
type flightVal uint8
const (
flight0 flightVal = iota + 1
flight1
flight2
flight3
flight4
flight4b
flight5
flight5b
flight6
)
func (f flightVal) String() string { //nolint:cyclop
switch f {
case flight0:
return "Flight 0"
case flight1:
return "Flight 1"
case flight2:
return "Flight 2"
case flight3:
return "Flight 3"
case flight4:
return "Flight 4"
case flight4b:
return "Flight 4b"
case flight5:
return "Flight 5"
case flight5b:
return "Flight 5b"
case flight6:
return "Flight 6"
default:
return "Invalid Flight"
}
}
func (f flightVal) isLastSendFlight() bool {
return f == flight6 || f == flight5b
}
func (f flightVal) isLastRecvFlight() bool {
return f == flight5 || f == flight4b
}
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