Make queryRandom async and add exports (#431)

queryRandom was currently only async for the `enrField` version.
However the basic queryRandom is also exported and thus gets
changed so it can be properly used as async proc.

Also added exports for the modules of which objects are used in
the discovery public API.

eth/p2p/discoveryv5/protocol.nim

@@ -76,13 +76,13 @@
 import
   std/[tables, sets, options, math, sequtils, algorithm],
   stew/shims/net as stewNet, json_serialization/std/net,
-  stew/endians2, chronicles, chronos, stint, bearssl, metrics,
+  stew/[endians2, results], chronicles, chronos, stint, bearssl, metrics,
   ".."/../[rlp, keys, async_utils],
   "."/[messages, encoding, node, routing_table, enr, random2, sessions, ip_vote, nodes_verification]
 
 import nimcrypto except toHex
 
-export options
+export options, results, node, enr
 
 declareCounter discovery_message_requests_outgoing,
   "Discovery protocol outgoing message requests", labels = ["response"]
@@ -422,8 +422,10 @@ proc receive*(d: Protocol, a: Address, packet: openArray[byte]) =
       # In that case we can add/update it to the routing table.
       if packet.node.isSome():
         let node = packet.node.get()
-        # Not filling table with nodes without correct IP in the ENR
-        # TODO: Should we care about this???
+        # Lets not add nodes without correct IP in the ENR to the routing table.
+        # The ENR could contain bogus IPs and although they would get removed
+        # on the next revalidation, one could spam these as the handshake
+        # message occurs on (first) incoming messages.
         if node.address.isSome() and a == node.address.get():
           if d.addNode(node):
             trace "Added new node to routing table after handshake", node
@@ -716,9 +718,9 @@ proc query*(d: Protocol, target: NodeId, k = BUCKET_SIZE): Future[seq[Node]]
   d.lastLookup = now(chronos.Moment)
   return queryBuffer
 
-proc queryRandom*(d: Protocol): Future[seq[Node]] =
+proc queryRandom*(d: Protocol): Future[seq[Node]] {.async.} =
   ## Perform a query for a random target, return all nodes discovered.
-  d.query(NodeId.random(d.rng[]))
+  return await d.query(NodeId.random(d.rng[]))
 
 proc queryRandom*(d: Protocol, enrField: (string, seq[byte])):
     Future[seq[Node]] {.async.} =