89 lines
2.0 KiB
Go
89 lines
2.0 KiB
Go
package node
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import (
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"errors"
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"net/netip"
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"time"
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"unsafe"
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)
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var errMalformedPacket = errors.New("malformed packet")
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const (
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packetTypePing = iota + 1
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packetTypePong
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)
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// ----------------------------------------------------------------------------
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type controlPacket struct {
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SrcIP byte
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RemoteAddr netip.AddrPort
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Payload any
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}
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// ----------------------------------------------------------------------------
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// A pingPacket is sent from a node acting as a client, to a node acting
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// as a server. It always contains the shared key the client is expecting
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// to use for data encryption with the server.
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type pingPacket struct {
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SentAt int64 // UnixMilli.
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SharedKey [32]byte
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}
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func newPingPacket(sharedKey []byte) (pp pingPacket) {
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pp.SentAt = time.Now().UnixMilli()
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copy(pp.SharedKey[:], sharedKey)
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return
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}
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func (p pingPacket) Marshal(buf []byte) []byte {
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buf = buf[:41]
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buf[0] = packetTypePing
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*(*uint64)(unsafe.Pointer(&buf[1])) = uint64(p.SentAt)
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copy(buf[9:41], p.SharedKey[:])
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return buf
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}
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func parsePingPacket(buf []byte) (p pingPacket, err error) {
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if len(buf) != 41 {
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return p, errMalformedPacket
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}
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p.SentAt = *(*int64)(unsafe.Pointer(&buf[1]))
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copy(p.SharedKey[:], buf[9:41])
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return
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}
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// ----------------------------------------------------------------------------
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// A pongPacket is sent by a node in a server role in response to a pingPacket.
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type pongPacket struct {
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SentAt int64 // UnixMilli.
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RecvdAt int64 // UnixMilli.
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}
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func newPongPacket(sentAt int64) (pp pongPacket) {
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pp.SentAt = sentAt
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pp.RecvdAt = time.Now().UnixMilli()
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return
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}
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func (p pongPacket) Marshal(buf []byte) []byte {
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buf = buf[:17]
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buf[0] = packetTypePong
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*(*uint64)(unsafe.Pointer(&buf[1])) = uint64(p.SentAt)
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*(*uint64)(unsafe.Pointer(&buf[9])) = uint64(p.RecvdAt)
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return buf
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}
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func parsePongPacket(buf []byte) (p pongPacket, err error) {
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if len(buf) != 17 {
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return p, errMalformedPacket
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}
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p.SentAt = *(*int64)(unsafe.Pointer(&buf[1]))
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p.RecvdAt = *(*int64)(unsafe.Pointer(&buf[9]))
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return
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}
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