feat: add waku_relay_get_connected_peers to libwaku (#3353)

library/libwaku.h

@@ -117,6 +117,11 @@ int waku_relay_get_num_connected_peers(void* ctx,
                            WakuCallBack callback,
                            void* userData);
 
+int waku_relay_get_connected_peers(void* ctx,
+                           const char* pubSubTopic,
+                           WakuCallBack callback,
+                           void* userData);
+
 int waku_relay_get_num_peers_in_mesh(void* ctx,
                            const char* pubSubTopic,
                            WakuCallBack callback,

library/libwaku.nim

@@ -429,6 +429,27 @@ proc waku_relay_get_num_connected_peers(
   initializeLibrary()
   checkLibwakuParams(ctx, callback, userData)
 
+  let pst = pubSubTopic.alloc()
+  defer:
+    deallocShared(pst)
+
+  handleRequest(
+    ctx,
+    RequestType.RELAY,
+    RelayRequest.createShared(RelayMsgType.NUM_CONNECTED_PEERS, pst),
+    callback,
+    userData,
+  )
+
+proc waku_relay_get_connected_peers(
+    ctx: ptr WakuContext,
+    pubSubTopic: cstring,
+    callback: WakuCallBack,
+    userData: pointer,
+): cint {.dynlib, exportc.} =
+  initializeLibrary()
+  checkLibwakuParams(ctx, callback, userData)
+
   let pst = pubSubTopic.alloc()
   defer:
     deallocShared(pst)

library/waku_thread/inter_thread_communication/requests/protocols/relay_request.nim

@@ -1,4 +1,4 @@
-import std/net
+import std/[net, sequtils, strutils]
 import chronicles, chronos, stew/byteutils, results
 import
   ../../../../../waku/waku_core/message/message,
@@ -8,12 +8,14 @@ import
   ../../../../../waku/waku_core/time, # Timestamp
   ../../../../../waku/waku_core/topics/pubsub_topic,
   ../../../../../waku/waku_relay/protocol,
+  ../../../../../waku/node/peer_manager,
   ../../../../alloc
 
 type RelayMsgType* = enum
   SUBSCRIBE
   UNSUBSCRIBE
   PUBLISH
+  NUM_CONNECTED_PEERS
   LIST_CONNECTED_PEERS
     ## to return the list of all connected peers to an specific pubsub topic
   LIST_MESH_PEERS
@@ -122,11 +124,17 @@ proc process*(
 
     let msgHash = computeMessageHash(pubSubTopic, msg).to0xHex
     return ok(msgHash)
-  of LIST_CONNECTED_PEERS:
+  of NUM_CONNECTED_PEERS:
     let numConnPeers = waku.node.wakuRelay.getNumConnectedPeers($self.pubsubTopic).valueOr:
-      error "LIST_CONNECTED_PEERS failed", error = error
+      error "NUM_CONNECTED_PEERS failed", error = error
       return err($error)
     return ok($numConnPeers)
+  of LIST_CONNECTED_PEERS:
+    let connPeers = waku.node.wakuRelay.getConnectedPeers($self.pubsubTopic).valueOr:
+      error "LIST_CONNECTED_PEERS failed", error = error
+      return err($error)
+    ## returns a comma-separated string of peerIDs
+    return ok(connPeers.mapIt($it).join(","))
   of LIST_MESH_PEERS:
     let numPeersInMesh = waku.node.wakuRelay.getNumPeersInMesh($self.pubsubTopic).valueOr:
       error "LIST_MESH_PEERS failed", error = error

waku/waku_relay/protocol.nim

@@ -539,22 +539,23 @@ proc publish*(
 
   return ok(relayedPeerCount)
 
-proc getNumConnectedPeers*(
+proc getConnectedPeers*(
     w: WakuRelay, pubsubTopic: PubsubTopic
-): Result[int, string] =
+): Result[seq[PeerId], string] =
-  ## Returns the number of connected peers and subscribed to the passed pubsub topic.
+  ## Returns the list of peerIds of connected peers and subscribed to the passed pubsub topic.
   ## The 'gossipsub' atribute is defined in the GossipSub ref object.
 
   if pubsubTopic == "":
     ## Return all the connected peers
-    var numConnPeers = 0
+    var peerIds = newSeq[PeerId]()
     for k, v in w.gossipsub:
-      numConnPeers.inc(v.len)
+      peerIds.add(toSeq(v).mapIt(it.peerId))
-    return ok(numConnPeers)
+      # alternatively: peerIds &= toSeq(v).mapIt(it.peerId)
+    return ok(peerIds)
 
   if not w.gossipsub.hasKey(pubsubTopic):
     return err(
-      "getNumConnectedPeers - there is no gossipsub peer for the given pubsub topic: " &
+      "getConnectedPeers - there is no gossipsub peer for the given pubsub topic: " &
         pubsubTopic
     )
 
@@ -562,8 +563,22 @@ proc getNumConnectedPeers*(
     w.gossipsub[pubsubTopic]
 
   let peers: HashSet[PubSubPeer] = peersRes.valueOr:
+    return
+      err("getConnectedPeers - exception accessing " & pubsubTopic & ": " & error.msg)
+
+  let peerIds = toSeq(peers).mapIt(it.peerId)
+  return ok(peerIds)
+
+proc getNumConnectedPeers*(
+    w: WakuRelay, pubsubTopic: PubsubTopic
+): Result[int, string] =
+  ## Returns the number of connected peers and subscribed to the passed pubsub topic.
+
+  ## Return all the connected peers
+  let peers = w.getConnectedPeers(pubsubTopic).valueOr:
     return err(
-      "getNumConnectedPeers - exception accessing " & pubsubTopic & ": " & error.msg
+      "getNumConnectedPeers - failed retrieving peers in mesh: " & pubsubTopic & ": " &
+        error
     )
 
   return ok(peers.len)