From 2d8be01db9ff7955081a37a0fefab990f8edaa12 Mon Sep 17 00:00:00 2001
From: Ludovic Chenut <ludovic@status.im>
Date: Mon, 12 Dec 2022 17:50:18 +0100
Subject: [PATCH] AutoRelay first commit

---
 libp2p/connmanager.nim                      |  7 ++
 libp2p/protocols/connectivity/autorelay.nim | 94 +++++++++++++++++++++
 libp2p/switch.nim                           | 25 ++++++
 3 files changed, 126 insertions(+)
 create mode 100644 libp2p/protocols/connectivity/autorelay.nim

diff --git a/libp2p/connmanager.nim b/libp2p/connmanager.nim
index b7ac3d87a..f26664a34 100644
--- a/libp2p/connmanager.nim
+++ b/libp2p/connmanager.nim
@@ -110,6 +110,13 @@ proc new*(C: type ConnManager,
 proc connCount*(c: ConnManager, peerId: PeerId): int =
   c.conns.getOrDefault(peerId).len
 
+proc connectedPeers*(c: ConnManager, dir: Direction): seq[PeerId] =
+  var peers = newSeq[PeerId]();
+  for peerId, conns in c.conns:
+    if conns.anyIt(it.dir == dir):
+      peers.add(peerId)
+  return peers
+
 proc addConnEventHandler*(c: ConnManager,
                           handler: ConnEventHandler,
                           kind: ConnEventKind) =
diff --git a/libp2p/protocols/connectivity/autorelay.nim b/libp2p/protocols/connectivity/autorelay.nim
new file mode 100644
index 000000000..bd7b20504
--- /dev/null
+++ b/libp2p/protocols/connectivity/autorelay.nim
@@ -0,0 +1,94 @@
+# Nim-LibP2P
+# Copyright (c) 2022 Status Research & Development GmbH
+# Licensed under either of
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+# at your option.
+# This file may not be copied, modified, or distributed except according to
+# those terms.
+
+when (NimMajor, NimMinor) < (1, 4):
+  {.push raises: [Defect].}
+else:
+  {.push raises: [].}
+
+import chronos, chronicles, times, tables, sequtils, options
+import ../../switch,
+       relay/[client, utils]
+
+logScope:
+  topics = "libp2p autorelay"
+
+type
+  OnReservationHandler = proc (ma: MultiAddress): Future[void] {.gcsafe, raises: [Defect].}
+
+  AutoRelay* = ref object of Service
+    running: bool
+    runner: Future[void]
+    client: RelayClient
+    npeers: int
+    peers: Table[PeerId, Future[void]]
+    onReservation: OnReservationHandler
+
+proc reserveAndUpdate(self: AutoRelay, peerId: PeerId) {.async.} =
+  while self.running:
+    let
+      rsvp = await self.client.reserve(peerId).wait(chronos.seconds(5))
+      relayedAddr = MultiAddress.init("").tryGet() # TODO
+#      relayedAddr = MultiAddress.init($(rsvp.addrs[0]) & "/p2p-circuit/p2p/" &
+#                              $(switch.peerInfo.peerId).tryGet()
+    await self.onReservation(relayedAddr)
+    await sleepAsync chronos.seconds(rsvp.expire.int64 - times.now().utc.toTime.toUnix)
+
+method setup*(self: AutoRelay, switch: Switch) {.async, gcsafe.} =
+  if self.inUse:
+    warn "Autorelay setup has already been called"
+    return
+  self.inUse = true
+  proc handlePeer(peerId: PeerId, event: PeerEvent) {.async.} =
+    if event.kind == Left and peerId in self.peers:
+      self.peers[peerId].cancel()
+
+method innerRun(self: AutoRelay, switch: Switch) {.async, gcsafe.} =
+  while true:
+    # Remove peers that failed
+    var peersToRemove: seq[PeerId]
+    for k, v in self.peers:
+      if v.failed():
+        peersToRemove.add(k)
+    for k in peersToRemove:
+      self.peers.del(k)
+
+    # Get all connected peers
+    let rng = newRng()
+    var connectedPeers = switch.connectedPeers(Direction.Out)
+    connectedPeers.keepItIf(RelayV2HopCodec in switch.peerStore[ProtoBook][it])
+    rng.shuffle(connectedPeers)
+
+    for peerId in switch.connectedPeers(Direction.Out):
+      if self.peers.len() >= self.npeers:
+        break
+      if RelayV2HopCodec in switch.peerStore[ProtoBook][peerId]:
+        self.peers[peerId] = self.reserveAndUpdate(peerId)
+    let peersFutures = toSeq(self.peers.values())
+    # await race(peersFutures) TODO
+
+method run*(self: AutoRelay, switch: Switch) {.async, gcsafe.} =
+  if self.running:
+    trace "Autorelay is already running"
+    return
+  self.running = true
+  self.runner = self.innerRun(switch)
+
+method stop*(self: AutoRelay, switch: Switch) {.async, gcsafe.} =
+  if not self.inUse:
+    warn "service is already stopped"
+  self.inUse = false
+  self.running = false
+  self.runner.cancel()
+
+method new(T: typedesc[AutoRelay],
+           npeers: int,
+           client: RelayClient,
+           onReservation: OnReservationHandler): T =
+  T(npeers: npeers, client: client, onReservation: onReservation)
diff --git a/libp2p/switch.nim b/libp2p/switch.nim
index b6fc22fec..c6fb0865b 100644
--- a/libp2p/switch.nim
+++ b/libp2p/switch.nim
@@ -74,6 +74,25 @@ type
       peerStore*: PeerStore
       nameResolver*: NameResolver
       started: bool
+      services*: seq[Service]
+
+    Service* = ref object of RootObj
+      inUse*: bool
+
+method setup*(self: Service, switch: Switch) {.base, async, gcsafe, public.} =
+  if self.inUse:
+    warn "service setup has already been called"
+    return
+  self.inUse = true
+
+method run*(self: Service, switch: Switch) {.base, async, gcsafe, public.} =
+  doAssert(false, "Not implemented!")
+
+method stop*(self: Service, switch: Switch) {.base, async, gcsafe, public.} =
+  if not self.inUse:
+    warn "service is already stopped"
+    return
+  self.inUse = false
 
 proc addConnEventHandler*(s: Switch,
                           handler: ConnEventHandler,
@@ -108,6 +127,12 @@ method addTransport*(s: Switch, t: Transport) =
   s.transports &= t
   s.dialer.addTransport(t)
 
+method addService*(switch: Switch, service: Service) =
+  switch.services.add(service)
+
+proc connectedPeers*(s: Switch, dir: Direction): seq[PeerId] =
+  s.connManager.connectedPeers(dir)
+
 proc isConnected*(s: Switch, peerId: PeerId): bool {.public.} =
   ## returns true if the peer has one or more
   ## associated connections