chore: resolving DNS IP and publishing it when no extIp provided

apps/wakunode2/internal_config.nim

@@ -1,9 +1,12 @@
 import
+  chronicles,
+  chronos,
+  libp2p/crypto/crypto,
+  libp2p/multiaddress,
+  libp2p/nameresolving/dnsresolver,
   std/options,
-  stew/shims/net,
   stew/results,
-  libp2p/crypto/crypto,
-  libp2p/multiaddress
+  stew/shims/net
 import
   ../../waku/common/utils/nat,
   ../../waku/node/config,
@@ -18,6 +21,23 @@ proc validateExtMultiAddrs*(vals: seq[string]):
     multiaddrs.add(multiaddr)
   return ok(multiaddrs)
 
+proc dnsResolve*(domain: string, conf: WakuNodeConf): Future[Result[string, string]] {.async} =
+
+  # Use conf's DNS servers
+  var nameServers: seq[TransportAddress]
+  for ip in conf.dnsAddrsNameServers:
+    nameServers.add(initTAddress(ip, Port(53))) # Assume all servers use port 53
+
+  let dnsResolver = DnsResolver.new(nameServers)
+
+  # Resolve domain IP
+  let resolved = await dnsResolver.resolveIp(domain, 0.Port, Domain.AF_UNSPEC)
+
+  if resolved.len > 0:
+    return ok(resolved[0].host) # Use only first answer
+  else:
+    return err("Could not resolve IP from DNS: empty response")
+
 proc networkConfiguration*(conf: WakuNodeConf,
                            clientId: string,
                            ): NetConfigResult =
@@ -30,7 +50,7 @@ proc networkConfiguration*(conf: WakuNodeConf,
   if natRes.isErr():
     return err("failed to setup NAT: " & $natRes.error)
 
-  let (extIp, extTcpPort, _) = natRes.get()
+  var (extIp, extTcpPort, _) = natRes.get()
 
   let
     dns4DomainName = if conf.dns4DomainName != "": some(conf.dns4DomainName)
@@ -69,6 +89,18 @@ proc networkConfiguration*(conf: WakuNodeConf,
         relay = conf.relay
       )
 
+  # Resolve and use DNS domain IP
+  if dns4DomainName.isSome() and extIp.isNone():
+    try:
+      let dnsRes = waitFor dnsResolve(conf.dns4DomainName, conf)
+
+      if dnsRes.isErr():
+        return err($dnsRes.error) # Pass error down the stack
+
+      extIp = some(ValidIpAddress.init(dnsRes.get()))
+    except CatchableError:
+      return err("Could not update extIp to resolved DNS IP: " & getCurrentExceptionMsg())
+
   # Wrap in none because NetConfig does not have a default constructor
   # TODO: We could change bindIp in NetConfig to be something less restrictive
   # than ValidIpAddress, which doesn't allow default construction

tests/test_wakunode.nim

@@ -1,7 +1,7 @@
 {.used.}
 
 import
-  std/sequtils,
+  std/[sequtils,strutils],
   stew/byteutils,
   stew/shims/net as stewNet,
   testutils/unittests,
@@ -215,6 +215,65 @@ suite "WakuNode":
       node.announcedAddresses.len == 1
       node.announcedAddresses.contains(expectedDns4Addr)
 
+  asyncTest "Node uses dns4 resolved ip in announced addresses if no extIp is provided":
+    let
+      nodeKey = generateSecp256k1Key()
+      bindIp = ValidIpAddress.init("0.0.0.0")
+      bindPort = Port(0)
+
+      domainName = "status.im"
+      node = newTestWakuNode(
+        nodeKey,
+        bindIp, bindPort,
+        dns4DomainName = some(domainName))
+
+    var ipStr = ""
+    var enrIp = node.enr.tryGet("ip", array[4, byte])
+
+    if enrIp.isSome():
+        ipStr &= $ipv4(enrIp.get())
+
+    # Check that the IP filled is the one received by the DNS lookup
+    # As IPs may change, we check that it's not empty, not the 0 IP and not localhost
+    check:
+      ipStr.len() > 0
+      not ipStr.contains("0.0.0.0")
+      not ipStr.contains("127.0.0.1")
+
+  asyncTest "Node creation fails when invalid dns4 address is provided":
+    let
+      nodeKey = generateSecp256k1Key()
+      bindIp = ValidIpAddress.init("0.0.0.0")
+      bindPort = Port(0)
+
+      inexistentDomain = "thisdomain.doesnot.exist"
+      invalidDomain = ""
+      expectedError = "Could not resolve IP from DNS: empty response"
+
+    var inexistentDomainErr, invalidDomainErr: string = ""
+
+    # Create node with inexistent domain
+    try:
+      let node = newTestWakuNode(
+        nodeKey,
+        bindIp, bindPort,
+        dns4DomainName = some(inexistentDomain))
+    except Exception as e:
+      inexistentDomainErr = e.msg
+
+    # Create node with invalid domain
+    try:
+      let node = newTestWakuNode(
+        nodeKey,
+        bindIp, bindPort,
+        dns4DomainName = some(invalidDomain))
+    except Exception as e:
+      invalidDomainErr = e.msg
+
+    # Check that exceptions were raised in both cases
+    check:
+      inexistentDomainErr == expectedError
+      invalidDomainErr == expectedError
 
   asyncTest "Agent string is set and advertised correctly":
     let

tests/testlib/wakunode.nim

@@ -13,6 +13,8 @@ import
   ../../../waku/node/peer_manager,
   ../../../waku/waku_enr,
   ../../../waku/waku_discv5,
+  ../../apps/wakunode2/internal_config,
+  ../wakunode2/test_app,
   ./common
 
 
@@ -38,10 +40,29 @@ proc newTestWakuNode*(nodeKey: crypto.PrivateKey,
                       discv5UdpPort = none(Port),
                       agentString = none(string),
                       peerStoreCapacity = none(int)): WakuNode =
+
+  var resolvedExtIp = extIp
+
+  # Update extPort to default value if it's missing and there's an extIp or a DNS domain 
+  let extPort = if (extIp.isSome() or dns4DomainName.isSome()) and
+                extPort.isNone():
+                some(Port(60000))
+              else:
+                extPort
+
+  if dns4DomainName.isSome() and extIp.isNone():
+    let conf = defaultTestWakuNodeConf()
+    # If there's an error resolving the IP, an exception is thrown and test fails 
+    let dnsRes = waitFor dnsResolve(dns4DomainName.get(), conf)
+    if dnsRes.isErr():
+      raise newException(Defect, $dnsRes.error)
+    else:
+      resolvedExtIp = some(ValidIpAddress.init(dnsRes.get()))
+
   let netConfigRes = NetConfig.init(
     bindIp = bindIp,
     bindPort = bindPort,
-    extIp = extIp,
+    extIp = resolvedExtIp,
     extPort = extPort,
     extMultiAddrs = extMultiAddrs,
     wsBindPort = wsBindPort,

tests/wakunode2/test_app.nim

@@ -15,12 +15,13 @@ import
   ../testlib/common,
   ../testlib/wakucore
 
-proc defaultTestWakuNodeConf(): WakuNodeConf =
+proc defaultTestWakuNodeConf*(): WakuNodeConf =
   WakuNodeConf(
     listenAddress: ValidIpAddress.init("127.0.0.1"),
     rpcAddress: ValidIpAddress.init("127.0.0.1"),
     restAddress: ValidIpAddress.init("127.0.0.1"),
     metricsServerAddress: ValidIpAddress.init("127.0.0.1"),
+    dnsAddrsNameServers: @[ValidIpAddress.init("1.1.1.1"), ValidIpAddress.init("1.0.0.1")],
     nat: "any",
     maxConnections: 50,
     topics: @["/waku/2/default-waku/proto"],