feat: making dns discovery async (#3175)

apps/chat2/chat2.nim

@@ -439,7 +439,7 @@ proc processInput(rfd: AsyncFD, rng: ref HmacDrbgContext) {.async.} =
 
     var wakuDnsDiscovery = WakuDnsDiscovery.init(dnsDiscoveryUrl.get(), resolver)
     if wakuDnsDiscovery.isOk:
-      let discoveredPeers = wakuDnsDiscovery.get().findPeers()
+      let discoveredPeers = await wakuDnsDiscovery.get().findPeers()
       if discoveredPeers.isOk:
         info "Connecting to discovered peers"
         discoveredNodes = discoveredPeers.get()

apps/networkmonitor/networkmonitor.nim

@@ -355,7 +355,9 @@ proc crawlNetwork(
 
 proc retrieveDynamicBootstrapNodes(
     dnsDiscovery: bool, dnsDiscoveryUrl: string, dnsDiscoveryNameServers: seq[IpAddress]
-): Result[seq[RemotePeerInfo], string] =
+): Future[Result[seq[RemotePeerInfo], string]] {.async.} =
+  ## Retrieve dynamic bootstrap nodes (DNS discovery)
+
   if dnsDiscovery and dnsDiscoveryUrl != "":
     # DNS discovery
     debug "Discovering nodes using Waku DNS discovery", url = dnsDiscoveryUrl
@@ -369,14 +371,15 @@ proc retrieveDynamicBootstrapNodes(
     proc resolver(domain: string): Future[string] {.async, gcsafe.} =
       trace "resolving", domain = domain
       let resolved = await dnsResolver.resolveTxt(domain)
-      return resolved[0] # Use only first answer
+      if resolved.len > 0:
+        return resolved[0] # Use only first answer
 
     var wakuDnsDiscovery = WakuDnsDiscovery.init(dnsDiscoveryUrl, resolver)
     if wakuDnsDiscovery.isOk():
-      return wakuDnsDiscovery.get().findPeers().mapErr(
-          proc(e: cstring): string =
-            $e
-        )
+      return (await wakuDnsDiscovery.get().findPeers()).mapErr(
+        proc(e: cstring): string =
+          $e
+      )
     else:
       warn "Failed to init Waku DNS discovery"
 
@@ -385,11 +388,11 @@ proc retrieveDynamicBootstrapNodes(
 
 proc getBootstrapFromDiscDns(
     conf: NetworkMonitorConf
-): Result[seq[enr.Record], string] =
+): Future[Result[seq[enr.Record], string]] {.async.} =
   try:
     let dnsNameServers = @[parseIpAddress("1.1.1.1"), parseIpAddress("1.0.0.1")]
     let dynamicBootstrapNodesRes =
-      retrieveDynamicBootstrapNodes(true, conf.dnsDiscoveryUrl, dnsNameServers)
+      await retrieveDynamicBootstrapNodes(true, conf.dnsDiscoveryUrl, dnsNameServers)
     if not dynamicBootstrapNodesRes.isOk():
       error("failed discovering peers from DNS")
     let dynamicBootstrapNodes = dynamicBootstrapNodesRes.get()
@@ -412,7 +415,7 @@ proc getBootstrapFromDiscDns(
 
 proc initAndStartApp(
     conf: NetworkMonitorConf
-): Result[(WakuNode, WakuDiscoveryV5), string] =
+): Future[Result[(WakuNode, WakuDiscoveryV5), string]] {.async.} =
   let bindIp =
     try:
       parseIpAddress("0.0.0.0")
@@ -472,7 +475,7 @@ proc initAndStartApp(
     else:
       nodeRes.get()
 
-  var discv5BootstrapEnrsRes = getBootstrapFromDiscDns(conf)
+  var discv5BootstrapEnrsRes = await getBootstrapFromDiscDns(conf)
   if discv5BootstrapEnrsRes.isErr():
     error("failed discovering peers from DNS")
   var discv5BootstrapEnrs = discv5BootstrapEnrsRes.get()
@@ -604,7 +607,7 @@ when isMainModule:
   let restClient = clientRest.get()
 
   # start waku node
-  let nodeRes = initAndStartApp(conf)
+  let nodeRes = waitFor initAndStartApp(conf)
   if nodeRes.isErr():
     error "could not start node"
     quit 1

library/waku_thread/inter_thread_communication/requests/discovery_request.nim

@@ -80,10 +80,10 @@ proc destroyShared(self: ptr DiscoveryRequest) =
 
 proc retrieveBootstrapNodes(
     enrTreeUrl: string, ipDnsServer: string
-): Result[seq[string], string] =
+): Future[Result[seq[string], string]] {.async.} =
   let dnsNameServers = @[parseIpAddress(ipDnsServer)]
-  let discoveredPeers: seq[RemotePeerInfo] = retrieveDynamicBootstrapNodes(
-    true, enrTreeUrl, dnsNameServers
+  let discoveredPeers: seq[RemotePeerInfo] = (
+    await retrieveDynamicBootstrapNodes(true, enrTreeUrl, dnsNameServers)
   ).valueOr:
     return err("failed discovering peers from DNS: " & $error)
 
@@ -126,7 +126,9 @@ proc process*(
 
     return ok("discv5 stopped correctly")
   of GET_BOOTSTRAP_NODES:
-    let nodes = retrieveBootstrapNodes($self[].enrTreeUrl, $self[].nameDnsServer).valueOr:
+    let nodes = (
+      await retrieveBootstrapNodes($self[].enrTreeUrl, $self[].nameDnsServer)
+    ).valueOr:
       error "GET_BOOTSTRAP_NODES failed", error = error
       return err($error)
 

tests/test_waku_dnsdisc.nim

@@ -79,7 +79,7 @@ suite "Waku DNS Discovery":
 
     var wakuDnsDisc = WakuDnsDiscovery.init(location, resolver).get()
 
-    let res = wakuDnsDisc.findPeers()
+    let res = await wakuDnsDisc.findPeers()
 
     check:
       # We have discovered all three nodes

waku/discovery/waku_discv5.nim

@@ -448,5 +448,15 @@ proc updateBootstrapRecords*(
       return err("wrong enr given: " & enrWithoutQuotes)
 
   self.protocol.bootstrapRecords = newRecords
+  self.protocol.seedTable()
 
   return ok()
+
+proc updateBootstrapRecords*(
+    self: var WakuDiscoveryV5, updatedRecords: seq[enr.Record]
+): void =
+  self.protocol.bootstrapRecords = updatedRecords
+
+  # If we're updating the table with nodes that already existed, it will log an error when trying
+  # to add a bootstrap node that was already there. That's ok.
+  self.protocol.seedTable()

waku/discovery/waku_dnsdisc.nim

@@ -6,7 +6,7 @@
 ## EIP-1459 is defined in https://eips.ethereum.org/EIPS/eip-1459
 
 import
-  std/[options, net],
+  std/[options, net, sequtils],
   chronicles,
   chronos,
   metrics,
@@ -40,22 +40,23 @@ proc emptyResolver*(domain: string): Future[string] {.async, gcsafe.} =
   debug "Empty resolver called", domain = domain
   return ""
 
-proc findPeers*(wdd: var WakuDnsDiscovery): Result[seq[RemotePeerInfo], cstring] =
+proc findPeers*(
+    wdd: WakuDnsDiscovery
+): Future[Result[seq[RemotePeerInfo], cstring]] {.async.} =
   ## Find peers to connect to using DNS based discovery
 
   info "Finding peers using Waku DNS discovery"
 
   # Synchronise client tree using configured resolver
   var tree: Tree
   try:
-    tree = wdd.client.getTree(wdd.resolver)
-      # @TODO: this is currently a blocking operation to not violate memory safety
+    tree = (await syncTree(wdd.resolver, wdd.client.loc)).tryGet()
   except Exception:
     error "Failed to synchronise client tree"
     waku_dnsdisc_errors.inc(labelValues = ["tree_sync_failure"])
     return err("Node discovery failed")
 
-  let discoveredEnr = wdd.client.getNodeRecords()
+  let discoveredEnr = tree.getNodes().mapIt(it.record)
 
   if discoveredEnr.len > 0:
     info "Successfully discovered ENR", count = discoveredEnr.len
@@ -97,7 +98,7 @@ proc init*(
 
 proc retrieveDynamicBootstrapNodes*(
     dnsDiscovery: bool, dnsDiscoveryUrl: string, dnsDiscoveryNameServers: seq[IpAddress]
-): Result[seq[RemotePeerInfo], string] =
+): Future[Result[seq[RemotePeerInfo], string]] {.async.} =
   ## Retrieve dynamic bootstrap nodes (DNS discovery)
 
   if dnsDiscovery and dnsDiscoveryUrl != "":
@@ -113,14 +114,15 @@ proc retrieveDynamicBootstrapNodes*(
     proc resolver(domain: string): Future[string] {.async, gcsafe.} =
       trace "resolving", domain = domain
       let resolved = await dnsResolver.resolveTxt(domain)
-      return resolved[0] # Use only first answer
+      if resolved.len > 0:
+        return resolved[0] # Use only first answer
 
     var wakuDnsDiscovery = WakuDnsDiscovery.init(dnsDiscoveryUrl, resolver)
     if wakuDnsDiscovery.isOk():
-      return wakuDnsDiscovery.get().findPeers().mapErr(
-          proc(e: cstring): string =
-            $e
-        )
+      return (await wakuDnsDiscovery.get().findPeers()).mapErr(
+        proc(e: cstring): string =
+          $e
+      )
     else:
       warn "Failed to init Waku DNS discovery"
 

waku/factory/waku.nim

@@ -58,6 +58,7 @@ type Waku* = ref object
 
   wakuDiscv5*: WakuDiscoveryV5
   dynamicBootstrapNodes: seq[RemotePeerInfo]
+  dnsRetryLoopHandle: Future[void]
   discoveryMngr: DiscoveryManager
 
   node*: WakuNode
@@ -215,17 +216,6 @@ proc new*(T: type Waku, confCopy: var WakuNodeConf): Result[Waku, string] =
       return err("Failed to generate key: " & $keyRes.error)
     confCopy.nodekey = some(keyRes.get())
 
-  debug "Retrieve dynamic bootstrap nodes"
-  let dynamicBootstrapNodesRes = waku_dnsdisc.retrieveDynamicBootstrapNodes(
-    confCopy.dnsDiscovery, confCopy.dnsDiscoveryUrl, confCopy.dnsDiscoveryNameServers
-  )
-  if dynamicBootstrapNodesRes.isErr():
-    error "Retrieving dynamic bootstrap nodes failed",
-      error = dynamicBootstrapNodesRes.error
-    return err(
-      "Retrieving dynamic bootstrap nodes failed: " & dynamicBootstrapNodesRes.error
-    )
-
   var relay = newCircuitRelay(confCopy.isRelayClient)
 
   let nodeRes = setupNode(confCopy, rng, relay)
@@ -255,7 +245,6 @@ proc new*(T: type Waku, confCopy: var WakuNodeConf): Result[Waku, string] =
     rng: rng,
     key: confCopy.nodekey.get(),
     node: node,
-    dynamicBootstrapNodes: dynamicBootstrapNodesRes.get(),
     deliveryMonitor: deliveryMonitor,
   )
 
@@ -351,7 +340,57 @@ proc updateWaku(waku: ptr Waku): Result[void, string] =
 
   return ok()
 
-proc startWaku*(waku: ptr Waku): Future[Result[void, string]] {.async: (raises: []).} =
+proc startDnsDiscoveryRetryLoop(waku: ptr Waku): Future[void] {.async.} =
+  while true:
+    await sleepAsync(30.seconds)
+    let dynamicBootstrapNodesRes = await waku_dnsdisc.retrieveDynamicBootstrapNodes(
+      waku.conf.dnsDiscovery, waku.conf.dnsDiscoveryUrl,
+      waku.conf.dnsDiscoveryNameServers,
+    )
+    if dynamicBootstrapNodesRes.isErr():
+      error "Retrieving dynamic bootstrap nodes failed",
+        error = dynamicBootstrapNodesRes.error
+      continue
+
+    waku[].dynamicBootstrapNodes = dynamicBootstrapNodesRes.get()
+
+    if not waku[].wakuDiscv5.isNil():
+      let dynamicBootstrapEnrs = waku[].dynamicBootstrapNodes
+        .filterIt(it.hasUdpPort())
+        .mapIt(it.enr.get().toUri())
+      var discv5BootstrapEnrs: seq[enr.Record]
+      # parse enrURIs from the configuration and add the resulting ENRs to the discv5BootstrapEnrs seq
+      for enrUri in dynamicBootstrapEnrs:
+        addBootstrapNode(enrUri, discv5BootstrapEnrs)
+
+      waku[].wakuDiscv5.updateBootstrapRecords(
+        waku[].wakuDiscv5.protocol.bootstrapRecords & discv5BootstrapEnrs
+      )
+
+    info "Connecting to dynamic bootstrap peers"
+    try:
+      await connectToNodes(
+        waku[].node, waku[].dynamicBootstrapNodes, "dynamic bootstrap"
+      )
+    except CatchableError:
+      error "failed to connect to dynamic bootstrap nodes: " & getCurrentExceptionMsg()
+    return
+
+proc startWaku*(waku: ptr Waku): Future[Result[void, string]] {.async.} =
+  debug "Retrieve dynamic bootstrap nodes"
+
+  let dynamicBootstrapNodesRes = await waku_dnsdisc.retrieveDynamicBootstrapNodes(
+    waku.conf.dnsDiscovery, waku.conf.dnsDiscoveryUrl, waku.conf.dnsDiscoveryNameServers
+  )
+
+  if dynamicBootstrapNodesRes.isErr():
+    error "Retrieving dynamic bootstrap nodes failed",
+      error = dynamicBootstrapNodesRes.error
+    # Start Dns Discovery retry loop
+    waku[].dnsRetryLoopHandle = waku.startDnsDiscoveryRetryLoop()
+  else:
+    waku[].dynamicBootstrapNodes = dynamicBootstrapNodesRes.get()
+
   if not waku[].conf.discv5Only:
     (await startNode(waku.node, waku.conf, waku.dynamicBootstrapNodes)).isOkOr:
       return err("error while calling startNode: " & $error)
@@ -400,3 +439,6 @@ proc stop*(waku: Waku): Future[void] {.async: (raises: [Exception]).} =
 
   if not waku.node.isNil():
     await waku.node.stop()
+
+  if not waku.dnsRetryLoopHandle.isNil():
+    await waku.dnsRetryLoopHandle.cancelAndWait()