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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package dtls
import (
"sync"
"github.com/pion/dtls/v3/pkg/crypto/prf"
"github.com/pion/dtls/v3/pkg/protocol/handshake"
)
type handshakeCacheItem struct {
typ handshake.Type
isClient bool
epoch uint16
messageSequence uint16
data []byte
}
type handshakeCachePullRule struct {
typ handshake.Type
epoch uint16
isClient bool
optional bool
}
type handshakeCache struct {
cache []*handshakeCacheItem
mu sync.Mutex
}
func newHandshakeCache() *handshakeCache {
return &handshakeCache{}
}
func (h *handshakeCache) push(data []byte, epoch, messageSequence uint16, typ handshake.Type, isClient bool) {
h.mu.Lock()
defer h.mu.Unlock()
h.cache = append(h.cache, &handshakeCacheItem{
data: append([]byte{}, data...),
epoch: epoch,
messageSequence: messageSequence,
typ: typ,
isClient: isClient,
})
}
// returns a list handshakes that match the requested rules
// the list will contain null entries for rules that can't be satisfied
// multiple entries may match a rule, but only the last match is returned (ie ClientHello with cookies).
func (h *handshakeCache) pull(rules ...handshakeCachePullRule) []*handshakeCacheItem {
h.mu.Lock()
defer h.mu.Unlock()
out := make([]*handshakeCacheItem, len(rules))
for i, r := range rules {
for _, c := range h.cache {
if c.typ == r.typ && c.isClient == r.isClient && c.epoch == r.epoch {
switch {
case out[i] == nil:
out[i] = c
case out[i].messageSequence < c.messageSequence:
out[i] = c
}
}
}
}
return out
}
// fullPullMap pulls all handshakes between rules[0] to rules[len(rules)-1] as map.
//
//nolint:cyclop
func (h *handshakeCache) fullPullMap(
startSeq int,
cipherSuite CipherSuite,
rules ...handshakeCachePullRule,
) (int, map[handshake.Type]handshake.Message, bool) {
h.mu.Lock()
defer h.mu.Unlock()
ci := make(map[handshake.Type]*handshakeCacheItem)
for _, rule := range rules {
var item *handshakeCacheItem
for _, c := range h.cache {
if c.typ == rule.typ && c.isClient == rule.isClient && c.epoch == rule.epoch {
switch {
case item == nil:
item = c
case item.messageSequence < c.messageSequence:
item = c
}
}
}
if !rule.optional && item == nil {
// Missing mandatory message.
return startSeq, nil, false
}
ci[rule.typ] = item
}
out := make(map[handshake.Type]handshake.Message)
seq := startSeq
ok := false
for _, r := range rules {
typ := r.typ
i := ci[typ]
if i == nil {
continue
}
var keyExchangeAlgorithm CipherSuiteKeyExchangeAlgorithm
if cipherSuite != nil {
keyExchangeAlgorithm = cipherSuite.KeyExchangeAlgorithm()
}
rawHandshake := &handshake.Handshake{
KeyExchangeAlgorithm: keyExchangeAlgorithm,
}
if err := rawHandshake.Unmarshal(i.data); err != nil {
return startSeq, nil, false
}
if uint16(seq) != rawHandshake.Header.MessageSequence { //nolint:gosec // G115
// There is a gap. Some messages are not arrived.
return startSeq, nil, false
}
seq++
ok = true
out[typ] = rawHandshake.Message
}
if !ok {
return seq, nil, false
}
return seq, out, true
}
// pullAndMerge calls pull and then merges the results, ignoring any null entries.
func (h *handshakeCache) pullAndMerge(rules ...handshakeCachePullRule) []byte {
merged := []byte{}
for _, p := range h.pull(rules...) {
if p != nil {
merged = append(merged, p.data...)
}
}
return merged
}
// sessionHash returns the session hash for Extended Master Secret support
// https://tools.ietf.org/html/draft-ietf-tls-session-hash-06#section-4
func (h *handshakeCache) sessionHash(hf prf.HashFunc, epoch uint16, additional ...[]byte) ([]byte, error) {
merged := []byte{}
// Order defined by https://tools.ietf.org/html/rfc5246#section-7.3
handshakeBuffer := h.pull(
handshakeCachePullRule{handshake.TypeClientHello, epoch, true, false},
handshakeCachePullRule{handshake.TypeServerHello, epoch, false, false},
handshakeCachePullRule{handshake.TypeCertificate, epoch, false, false},
handshakeCachePullRule{handshake.TypeServerKeyExchange, epoch, false, false},
handshakeCachePullRule{handshake.TypeCertificateRequest, epoch, false, false},
handshakeCachePullRule{handshake.TypeServerHelloDone, epoch, false, false},
handshakeCachePullRule{handshake.TypeCertificate, epoch, true, false},
handshakeCachePullRule{handshake.TypeClientKeyExchange, epoch, true, false},
)
for _, p := range handshakeBuffer {
if p == nil {
continue
}
merged = append(merged, p.data...)
}
for _, a := range additional {
merged = append(merged, a...)
}
hash := hf()
if _, err := hash.Write(merged); err != nil {
return []byte{}, err
}
return hash.Sum(nil), nil
}
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