libp2p-dht/codexdht/private/eth/p2p/discoveryv5/sessions.nim

63 lines
2.1 KiB
Nim

# codex-dht - Codex DHT
# Copyright (c) 2022 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
#
## Session cache as mentioned at
## https://github.com/ethereum/devp2p/blob/master/discv5/discv5-theory.md#session-cache
##
{.push raises: [Defect].}
import
std/options,
stint, stew/endians2, stew/shims/net,
node, lru
export lru
const
aesKeySize* = 128 div 8
keySize = sizeof(NodeId) +
16 + # max size of ip address (ipv6)
2 # Sizeof port
type
AesKey* = array[aesKeySize, byte]
SessionKey* = array[keySize, byte]
SessionValue* = array[sizeof(AesKey) + sizeof(AesKey), byte]
Sessions* = LRUCache[SessionKey, SessionValue]
func makeKey(id: NodeId, address: Address): SessionKey =
var pos = 0
result[pos ..< pos+sizeof(id)] = toBytes(id)
pos.inc(sizeof(id))
case address.ip.family
of IpAddressFamily.IpV4:
result[pos ..< pos+sizeof(address.ip.address_v4)] = address.ip.address_v4
of IpAddressFamily.IpV6:
result[pos ..< pos+sizeof(address.ip.address_v6)] = address.ip.address_v6
pos.inc(sizeof(address.ip.address_v6))
result[pos ..< pos+sizeof(address.port)] = toBytes(address.port.uint16)
func store*(s: var Sessions, id: NodeId, address: Address, r, w: AesKey) =
var value: array[sizeof(r) + sizeof(w), byte]
value[0 .. 15] = r
value[16 .. ^1] = w
s.put(makeKey(id, address), value)
func load*(s: var Sessions, id: NodeId, address: Address, r, w: var AesKey): bool =
let res = s.get(makeKey(id, address))
if res.isSome():
let val = res.get()
copyMem(addr r[0], unsafeAddr val[0], sizeof(r))
copyMem(addr w[0], unsafeAddr val[sizeof(r)], sizeof(w))
return true
else:
return false
func del*(s: var Sessions, id: NodeId, address: Address) =
s.del(makeKey(id, address))