cwinfo/yggdrasil-go
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change how nonce is tracked, so we allow packets if we've recently received a highest nonce ever, but don't bother tracking all received nonce values, this means duplicate packets are possible but only for a small window of time (and significantly reduces memory usage per session)

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This commit is contained in:
Arceliar 2019-08-31 17:39:05 -05:00
parent 0806f3e6ea
commit cabdc27a54
1 changed files with 33 additions and 74 deletions
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45
src/yggdrasil/session.go
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@ -6,7 +6,6 @@ package yggdrasil
import (
"bytes"
"container/heap"
"sync"
"time"
@ -20,21 +19,6 @@ import (
// Duration that we keep track of old nonces per session, to allow some out-of-order packet delivery
const nonceWindow = time.Second
// A heap of nonces, used with a map[nonce]time to allow out-of-order packets a little time to arrive without rejecting them
type nonceHeap []crypto.BoxNonce
func (h nonceHeap) Len() int { return len(h) }
func (h nonceHeap) Less(i, j int) bool { return h[i].Minus(&h[j]) < 0 }
func (h nonceHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
func (h *nonceHeap) Push(x interface{}) { *h = append(*h, x.(crypto.BoxNonce)) }
func (h *nonceHeap) Pop() interface{} {
l := len(*h)
var n crypto.BoxNonce
n, *h = (*h)[l-1], (*h)[:l-1]
return n
}
func (h nonceHeap) peek() *crypto.BoxNonce { return &h[0] }
// All the information we know about an active session.
// This includes coords, permanent and ephemeral keys, handles and nonces, various sorts of timing information for timeout and maintenance, and some metadata for the admin API.
type sessionInfo struct {
@ -51,8 +35,6 @@ type sessionInfo struct {
theirHandle crypto.Handle //
myHandle crypto.Handle //
theirNonce crypto.BoxNonce //
theirNonceHeap nonceHeap // priority queue to keep track of the lowest nonce we recently accepted
theirNonceMap map[crypto.BoxNonce]time.Time // time we added each nonce to the heap
myNonce crypto.BoxNonce //
theirMTU uint16 //
myMTU uint16 //
@ -105,8 +87,6 @@ func (s *sessionInfo) _update(p *sessionPing) bool {
s.theirHandle = p.Handle
s.sharedSesKey = *crypto.GetSharedKey(&s.mySesPriv, &s.theirSesPub)
s.theirNonce = crypto.BoxNonce{}
s.theirNonceHeap = nil
s.theirNonceMap = make(map[crypto.BoxNonce]time.Time)
}
if p.MTU >= 1280 || p.MTU == 0 {
s.theirMTU = p.MTU
@ -420,36 +400,16 @@ func (sinfo *sessionInfo) _nonceIsOK(theirNonce *crypto.BoxNonce) bool {
// This is newer than the newest nonce we've seen
return true
}
if len(sinfo.theirNonceHeap) > 0 {
if theirNonce.Minus(sinfo.theirNonceHeap.peek()) > 0 {
if _, isIn := sinfo.theirNonceMap[*theirNonce]; !isIn {
// This nonce is recent enough that we keep track of older nonces, but it's not one we've seen yet
return true
}
}
}
return false
return time.Since(sinfo.time) < nonceWindow
}
// Updates the nonce mask by (possibly) shifting the bitmask and setting the bit corresponding to this nonce to 1, and then updating the most recent nonce
func (sinfo *sessionInfo) _updateNonce(theirNonce *crypto.BoxNonce) {
// Start with some cleanup
for len(sinfo.theirNonceHeap) > 64 {
if time.Since(sinfo.theirNonceMap[*sinfo.theirNonceHeap.peek()]) < nonceWindow {
// This nonce is still fairly new, so keep it around
break
}
// TODO? reallocate the map in some cases, to free unused map space?
delete(sinfo.theirNonceMap, *sinfo.theirNonceHeap.peek())
heap.Pop(&sinfo.theirNonceHeap)
}
if theirNonce.Minus(&sinfo.theirNonce) > 0 {
// This nonce is the newest we've seen, so make a note of that
sinfo.theirNonce = *theirNonce
sinfo.time = time.Now()
}
// Add it to the heap/map so we know not to allow it again
heap.Push(&sinfo.theirNonceHeap, *theirNonce)
sinfo.theirNonceMap[*theirNonce] = time.Now()
}
// Resets all sessions to an uninitialized state.
@ -515,7 +475,6 @@ func (sinfo *sessionInfo) _recvPacket(p *wire_trafficPacket) {
return
}
sinfo._updateNonce(&p.Nonce)
sinfo.time = time.Now()
sinfo.bytesRecvd += uint64(len(bs))
sinfo.conn.recvMsg(sinfo, bs)
}