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conn_id_manager.go
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conn_id_manager.go
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package quic
import (
"fmt"
"github.com/hugefiver/quic/internal/protocol"
"github.com/hugefiver/quic/internal/qerr"
"github.com/hugefiver/quic/internal/utils"
list "github.com/hugefiver/quic/internal/utils/linkedlist"
"github.com/hugefiver/quic/internal/wire"
)
type newConnID struct {
SequenceNumber uint64
ConnectionID protocol.ConnectionID
StatelessResetToken protocol.StatelessResetToken
}
type connIDManager struct {
queue list.List[newConnID]
handshakeComplete bool
activeSequenceNumber uint64
highestRetired uint64
activeConnectionID protocol.ConnectionID
activeStatelessResetToken *protocol.StatelessResetToken
// We change the connection ID after sending on average
// protocol.PacketsPerConnectionID packets. The actual value is randomized
// hide the packet loss rate from on-path observers.
rand utils.Rand
packetsSinceLastChange uint32
packetsPerConnectionID uint32
addStatelessResetToken func(protocol.StatelessResetToken)
removeStatelessResetToken func(protocol.StatelessResetToken)
queueControlFrame func(wire.Frame)
}
func newConnIDManager(
initialDestConnID protocol.ConnectionID,
addStatelessResetToken func(protocol.StatelessResetToken),
removeStatelessResetToken func(protocol.StatelessResetToken),
queueControlFrame func(wire.Frame),
) *connIDManager {
return &connIDManager{
activeConnectionID: initialDestConnID,
addStatelessResetToken: addStatelessResetToken,
removeStatelessResetToken: removeStatelessResetToken,
queueControlFrame: queueControlFrame,
}
}
func (h *connIDManager) AddFromPreferredAddress(connID protocol.ConnectionID, resetToken protocol.StatelessResetToken) error {
return h.addConnectionID(1, connID, resetToken)
}
func (h *connIDManager) Add(f *wire.NewConnectionIDFrame) error {
if err := h.add(f); err != nil {
return err
}
if h.queue.Len() >= protocol.MaxActiveConnectionIDs {
return &qerr.TransportError{ErrorCode: qerr.ConnectionIDLimitError}
}
return nil
}
func (h *connIDManager) add(f *wire.NewConnectionIDFrame) error {
// If the NEW_CONNECTION_ID frame is reordered, such that its sequence number is smaller than the currently active
// connection ID or if it was already retired, send the RETIRE_CONNECTION_ID frame immediately.
if f.SequenceNumber < h.activeSequenceNumber || f.SequenceNumber < h.highestRetired {
h.queueControlFrame(&wire.RetireConnectionIDFrame{
SequenceNumber: f.SequenceNumber,
})
return nil
}
// Retire elements in the queue.
// Doesn't retire the active connection ID.
if f.RetirePriorTo > h.highestRetired {
var next *list.Element[newConnID]
for el := h.queue.Front(); el != nil; el = next {
if el.Value.SequenceNumber >= f.RetirePriorTo {
break
}
next = el.Next()
h.queueControlFrame(&wire.RetireConnectionIDFrame{
SequenceNumber: el.Value.SequenceNumber,
})
h.queue.Remove(el)
}
h.highestRetired = f.RetirePriorTo
}
if f.SequenceNumber == h.activeSequenceNumber {
return nil
}
if err := h.addConnectionID(f.SequenceNumber, f.ConnectionID, f.StatelessResetToken); err != nil {
return err
}
// Retire the active connection ID, if necessary.
if h.activeSequenceNumber < f.RetirePriorTo {
// The queue is guaranteed to have at least one element at this point.
h.updateConnectionID()
}
return nil
}
func (h *connIDManager) addConnectionID(seq uint64, connID protocol.ConnectionID, resetToken protocol.StatelessResetToken) error {
// insert a new element at the end
if h.queue.Len() == 0 || h.queue.Back().Value.SequenceNumber < seq {
h.queue.PushBack(newConnID{
SequenceNumber: seq,
ConnectionID: connID,
StatelessResetToken: resetToken,
})
return nil
}
// insert a new element somewhere in the middle
for el := h.queue.Front(); el != nil; el = el.Next() {
if el.Value.SequenceNumber == seq {
if !el.Value.ConnectionID.Equal(connID) {
return fmt.Errorf("received conflicting connection IDs for sequence number %d", seq)
}
if el.Value.StatelessResetToken != resetToken {
return fmt.Errorf("received conflicting stateless reset tokens for sequence number %d", seq)
}
break
}
if el.Value.SequenceNumber > seq {
h.queue.InsertBefore(newConnID{
SequenceNumber: seq,
ConnectionID: connID,
StatelessResetToken: resetToken,
}, el)
break
}
}
return nil
}
func (h *connIDManager) updateConnectionID() {
h.queueControlFrame(&wire.RetireConnectionIDFrame{
SequenceNumber: h.activeSequenceNumber,
})
h.highestRetired = utils.Max(h.highestRetired, h.activeSequenceNumber)
if h.activeStatelessResetToken != nil {
h.removeStatelessResetToken(*h.activeStatelessResetToken)
}
front := h.queue.Remove(h.queue.Front())
h.activeSequenceNumber = front.SequenceNumber
h.activeConnectionID = front.ConnectionID
h.activeStatelessResetToken = &front.StatelessResetToken
h.packetsSinceLastChange = 0
h.packetsPerConnectionID = protocol.PacketsPerConnectionID/2 + uint32(h.rand.Int31n(protocol.PacketsPerConnectionID))
h.addStatelessResetToken(*h.activeStatelessResetToken)
}
func (h *connIDManager) Close() {
if h.activeStatelessResetToken != nil {
h.removeStatelessResetToken(*h.activeStatelessResetToken)
}
}
// is called when the server performs a Retry
// and when the server changes the connection ID in the first Initial sent
func (h *connIDManager) ChangeInitialConnID(newConnID protocol.ConnectionID) {
if h.activeSequenceNumber != 0 {
panic("expected first connection ID to have sequence number 0")
}
h.activeConnectionID = newConnID
}
// is called when the server provides a stateless reset token in the transport parameters
func (h *connIDManager) SetStatelessResetToken(token protocol.StatelessResetToken) {
if h.activeSequenceNumber != 0 {
panic("expected first connection ID to have sequence number 0")
}
h.activeStatelessResetToken = &token
h.addStatelessResetToken(token)
}
func (h *connIDManager) SentPacket() {
h.packetsSinceLastChange++
}
func (h *connIDManager) shouldUpdateConnID() bool {
if !h.handshakeComplete {
return false
}
// initiate the first change as early as possible (after handshake completion)
if h.queue.Len() > 0 && h.activeSequenceNumber == 0 {
return true
}
// For later changes, only change if
// 1. The queue of connection IDs is filled more than 50%.
// 2. We sent at least PacketsPerConnectionID packets
return 2*h.queue.Len() >= protocol.MaxActiveConnectionIDs &&
h.packetsSinceLastChange >= h.packetsPerConnectionID
}
func (h *connIDManager) Get() protocol.ConnectionID {
if h.shouldUpdateConnID() {
h.updateConnectionID()
}
return h.activeConnectionID
}
func (h *connIDManager) SetHandshakeComplete() {
h.handshakeComplete = true
}