mirror of https://github.com/jetkvm/kvm.git
106 lines
2.9 KiB
Go
106 lines
2.9 KiB
Go
// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
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// SPDX-License-Identifier: MIT
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package dtls
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import (
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"crypto/rand"
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"github.com/pion/dtls/v3/pkg/protocol"
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"github.com/pion/dtls/v3/pkg/protocol/extension"
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"github.com/pion/dtls/v3/pkg/protocol/handshake"
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"github.com/pion/dtls/v3/pkg/protocol/recordlayer"
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)
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// RandomCIDGenerator is a random Connection ID generator where CID is the
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// specified size. Specifying a size of 0 will indicate to peers that sending a
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// Connection ID is not necessary.
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func RandomCIDGenerator(size int) func() []byte {
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return func() []byte {
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cid := make([]byte, size)
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if _, err := rand.Read(cid); err != nil {
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panic(err) //nolint -- nonrecoverable
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}
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return cid
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}
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}
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// OnlySendCIDGenerator enables sending Connection IDs negotiated with a peer,
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// but indicates to the peer that sending Connection IDs in return is not
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// necessary.
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func OnlySendCIDGenerator() func() []byte {
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return func() []byte {
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return nil
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}
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}
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// cidDatagramRouter extracts connection IDs from incoming datagram payloads and
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// uses them to route to the proper connection.
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// NOTE: properly routing datagrams based on connection IDs requires using
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// constant size connection IDs.
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func cidDatagramRouter(size int) func([]byte) (string, bool) {
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return func(packet []byte) (string, bool) {
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pkts, err := recordlayer.ContentAwareUnpackDatagram(packet, size)
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if err != nil || len(pkts) < 1 {
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return "", false
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}
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for _, pkt := range pkts {
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h := &recordlayer.Header{
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ConnectionID: make([]byte, size),
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}
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if err := h.Unmarshal(pkt); err != nil {
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continue
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}
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if h.ContentType != protocol.ContentTypeConnectionID {
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continue
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}
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return string(h.ConnectionID), true
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}
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return "", false
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}
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}
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// cidConnIdentifier extracts connection IDs from outgoing ServerHello records
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// and associates them with the associated connection.
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// NOTE: a ServerHello should always be the first record in a datagram if
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// multiple are present, so we avoid iterating through all packets if the first
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// is not a ServerHello.
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func cidConnIdentifier() func([]byte) (string, bool) { //nolint:cyclop
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return func(packet []byte) (string, bool) {
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pkts, err := recordlayer.UnpackDatagram(packet)
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if err != nil || len(pkts) < 1 {
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return "", false
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}
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var h recordlayer.Header
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if hErr := h.Unmarshal(pkts[0]); hErr != nil {
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return "", false
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}
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if h.ContentType != protocol.ContentTypeHandshake {
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return "", false
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}
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var hh handshake.Header
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var sh handshake.MessageServerHello
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for _, pkt := range pkts {
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if hhErr := hh.Unmarshal(pkt[recordlayer.FixedHeaderSize:]); hhErr != nil {
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continue
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}
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if err = sh.Unmarshal(pkt[recordlayer.FixedHeaderSize+handshake.HeaderLength:]); err == nil {
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break
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}
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}
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if err != nil {
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return "", false
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}
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for _, ext := range sh.Extensions {
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if e, ok := ext.(*extension.ConnectionID); ok {
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return string(e.CID), true
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}
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}
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return "", false
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}
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}
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