chore: add parseDatagramDestination (#122)

quic/listener.nim

@@ -47,7 +47,7 @@ proc getOrCreateConnection*(
     rng: ref HmacDrbgContext,
 ): Opt[Connection] =
   var connection: Connection
-  let destination = parseDatagram(msg).destination
+  let destination = parseDatagramDestination(msg)
   if not listener.hasConnection(destination):
     if not shouldAccept(msg):
       return Opt.none(Connection)

quic/transport/ngtcp2/native.nim

@@ -7,7 +7,9 @@ import ./native/parsedatagram
 import ./native/picotls
 import ./native/certificateverifier
 
-export parseDatagram
+export parseDatagramInfo
+export parseDatagramDestination
+export shouldAccept
 export Ngtcp2Connection
 export newNgtcp2Client
 export newNgtcp2Server

quic/transport/ngtcp2/native/parsedatagram.nim

@@ -9,7 +9,7 @@ proc toConnectionId(p: ptr byte, length: uint): ConnectionId =
   copyMem(bytes.toPtr, p, length)
   ConnectionId(bytes)
 
-proc parseDatagram*(datagram: openArray[byte]): PacketInfo =
+proc parseDatagramInfo*(datagram: openArray[byte]): PacketInfo =
   var version: ngtcp2_version_cid
   checkResult ngtcp2_pkt_decode_version_cid(
     addr version, unsafeAddr datagram[0], datagram.len.uint, DefaultConnectionIdLength
@@ -20,6 +20,13 @@ proc parseDatagram*(datagram: openArray[byte]): PacketInfo =
     version: version.version.uint32,
   )
 
+proc parseDatagramDestination*(datagram: openArray[byte]): ConnectionId =
+  var version: ngtcp2_version_cid
+  checkResult ngtcp2_pkt_decode_version_cid(
+    addr version, unsafeAddr datagram[0], datagram.len.uint, DefaultConnectionIdLength
+  )
+  return toConnectionId(version.dcid, version.dcidlen)
+
 proc shouldAccept*(datagram: openArray[byte]): bool =
   var hd: ngtcp2_pkt_hd
   let ret = ngtcp2_accept(hd.unsafeAddr, datagram[0].unsafeAddr, datagram.len.uint)

quic/transport/ngtcp2/native/server.nim

@@ -105,15 +105,13 @@ proc newNgtcp2Server*(
   nConn.tlsContext = tlsContext
   nConn
 
-proc extractIds(datagram: openArray[byte]): tuple[source, dest: ngtcp2_cid] =
-  let info = parseDatagram(datagram)
-  (source: info.source.toCid, dest: info.destination.toCid)
-
 proc newNgtcp2Server*(
     tlsContext: PicoTLSContext,
     local, remote: TransportAddress,
     datagram: openArray[byte],
     rng: ref HmacDrbgContext,
 ): Ngtcp2Connection =
-  let (source, destination) = extractIds(datagram)
-  newNgtcp2Server(tlsContext, local, remote, source, destination, rng)
+  let info = parseDatagramInfo(datagram)
+  newNgtcp2Server(
+    tlsContext, local, remote, info.source.toCid, info.destination.toCid, rng
+  )

quic/transport/parsedatagram.nim

@@ -1,3 +1,5 @@
 import ./ngtcp2/native/parsedatagram
 
-export parseDatagram
+export parseDatagramInfo
+export parseDatagramDestination
+export shouldAccept

tests/quic/testParseDatagram.nim

@@ -1,31 +1,32 @@
 import std/unittest
 
 import ngtcp2
-import bearssl/rand
 import quic/helpers/rand
 import quic/transport/[packets, parsedatagram, version]
 
 suite "parse ngtcp2 packet info":
   var packet: Packet
   var datagram: array[4096, byte]
-  var rng: ref HmacDrbgContext
 
   setup:
+    let rng = newRng()
     packet = initialPacket(CurrentQuicVersion)
-    rng = newRng()
     packet.source = randomConnectionId(rng)
     packet.destination = randomConnectionId(rng)
     datagram = typeof(datagram).default
     datagram.write(packet)
 
   test "extracts destination id":
-    let info = parseDatagram(datagram)
+    let info = parseDatagramInfo(datagram)
     check info.destination == packet.destination
 
+    let destination = parseDatagramDestination(datagram)
+    check info.destination == destination
+
   test "extracts source id":
-    let info = parseDatagram(datagram)
+    let info = parseDatagramInfo(datagram)
     check info.source == packet.source
 
   test "extracts version":
-    let info = parseDatagram(datagram)
+    let info = parseDatagramInfo(datagram)
     check info.version == packet.initial.version