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keep track of recent nonces with a heap and a map instead of a fixed-size bitmask

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Arceliar 2019-08-16 18:37:16 -05:00
parent fdac8932a8
commit 03b8af9f1a
1 changed files with 83 additions and 48 deletions
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131
src/yggdrasil/session.go
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@ -6,6 +6,7 @@ package yggdrasil
import (
"bytes"
"container/heap"
"errors"
"sync"
"time"
@ -15,42 +16,62 @@ import (
"github.com/yggdrasil-network/yggdrasil-go/src/util"
)
// 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
// Less is backwards so the oldest node is the highest priority for Pop
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[len(h)-1] }
// 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 {
mutex sync.Mutex // Protects all of the below, use it any time you read/chance the contents of a session
core *Core //
reconfigure chan chan error //
theirAddr address.Address //
theirSubnet address.Subnet //
theirPermPub crypto.BoxPubKey //
theirSesPub crypto.BoxPubKey //
mySesPub crypto.BoxPubKey //
mySesPriv crypto.BoxPrivKey //
sharedSesKey crypto.BoxSharedKey // derived from session keys
theirHandle crypto.Handle //
myHandle crypto.Handle //
theirNonce crypto.BoxNonce //
theirNonceMask uint64 //
myNonce crypto.BoxNonce //
theirMTU uint16 //
myMTU uint16 //
wasMTUFixed bool // Was the MTU fixed by a receive error?
timeOpened time.Time // Time the sessino was opened
time time.Time // Time we last received a packet
mtuTime time.Time // time myMTU was last changed
pingTime time.Time // time the first ping was sent since the last received packet
pingSend time.Time // time the last ping was sent
coords []byte // coords of destination
reset bool // reset if coords change
tstamp int64 // ATOMIC - tstamp from their last session ping, replay attack mitigation
bytesSent uint64 // Bytes of real traffic sent in this session
bytesRecvd uint64 // Bytes of real traffic received in this session
init chan struct{} // Closed when the first session pong arrives, used to signal that the session is ready for initial use
cancel util.Cancellation // Used to terminate workers
fromRouter chan wire_trafficPacket // Received packets go here, to be decrypted by the session
recv chan []byte // Decrypted packets go here, picked up by the associated Conn
send chan FlowKeyMessage // Packets with optional flow key go here, to be encrypted and sent
mutex sync.Mutex // Protects all of the below, use it any time you read/chance the contents of a session
core *Core //
reconfigure chan chan error //
theirAddr address.Address //
theirSubnet address.Subnet //
theirPermPub crypto.BoxPubKey //
theirSesPub crypto.BoxPubKey //
mySesPub crypto.BoxPubKey //
mySesPriv crypto.BoxPrivKey //
sharedSesKey crypto.BoxSharedKey // derived from session keys
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 //
wasMTUFixed bool // Was the MTU fixed by a receive error?
timeOpened time.Time // Time the sessino was opened
time time.Time // Time we last received a packet
mtuTime time.Time // time myMTU was last changed
pingTime time.Time // time the first ping was sent since the last received packet
pingSend time.Time // time the last ping was sent
coords []byte // coords of destination
reset bool // reset if coords change
tstamp int64 // ATOMIC - tstamp from their last session ping, replay attack mitigation
bytesSent uint64 // Bytes of real traffic sent in this session
bytesRecvd uint64 // Bytes of real traffic received in this session
init chan struct{} // Closed when the first session pong arrives, used to signal that the session is ready for initial use
cancel util.Cancellation // Used to terminate workers
fromRouter chan wire_trafficPacket // Received packets go here, to be decrypted by the session
recv chan []byte // Decrypted packets go here, picked up by the associated Conn
send chan FlowKeyMessage // Packets with optional flow key go here, to be encrypted and sent
}
func (sinfo *sessionInfo) doFunc(f func()) {
@ -87,7 +108,8 @@ func (s *sessionInfo) update(p *sessionPing) bool {
s.theirHandle = p.Handle
s.sharedSesKey = *crypto.GetSharedKey(&s.mySesPriv, &s.theirSesPub)
s.theirNonce = crypto.BoxNonce{}
s.theirNonceMask = 0
s.theirNonceHeap = nil
s.theirNonceMap = make(map[crypto.BoxNonce]time.Time)
}
if p.MTU >= 1280 || p.MTU == 0 {
s.theirMTU = p.MTU
@ -400,27 +422,40 @@ func (sinfo *sessionInfo) getMTU() uint16 {
// Checks if a packet's nonce is recent enough to fall within the window of allowed packets, and not already received.
func (sinfo *sessionInfo) nonceIsOK(theirNonce *crypto.BoxNonce) bool {
// The bitmask is to allow for some non-duplicate out-of-order packets
diff := theirNonce.Minus(&sinfo.theirNonce)
if diff > 0 {
if theirNonce.Minus(&sinfo.theirNonce) > 0 {
// This is newer than the newest nonce we've seen
return true
}
return ^sinfo.theirNonceMask&(0x01<<uint64(-diff)) != 0
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
}
// 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) {
// Shift nonce mask if needed
// Set bit
diff := theirNonce.Minus(&sinfo.theirNonce)
if diff > 0 {
// This nonce is newer, so shift the window before setting the bit, and update theirNonce in the session info.
sinfo.theirNonceMask <<= uint64(diff)
sinfo.theirNonceMask &= 0x01
sinfo.theirNonce = *theirNonce
} else {
// This nonce is older, so set the bit but do not shift the window.
sinfo.theirNonceMask &= 0x01 << uint64(-diff)
// 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
}
// 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.