feat(kad): client mode (#1908)

Author: gmelodie

libp2p/protocols/kademlia.nim

@@ -78,6 +78,7 @@ proc new*(
     bootstrapNodes: seq[(PeerId, seq[MultiAddress])] = @[],
     config: KadDHTConfig = KadDHTConfig.new(),
     rng: ref HmacDrbgContext = newRng(),
+    client: bool = false,
 ): T {.raises: [].} =
   var rtable = RoutingTable.new(
     switch.peerInfo.peerId.toKey(),
@@ -94,40 +95,41 @@ proc new*(
   )
 
   kad.codec = KadCodec
-  kad.handler = proc(
-      conn: Connection, proto: string
-  ) {.async: (raises: [CancelledError]).} =
-    defer:
-      await conn.close()
-    while not conn.atEof:
-      let buf =
-        try:
-          await conn.readLp(MaxMsgSize)
-        except LPStreamEOFError:
+  if not client:
+    kad.handler = proc(
+        conn: Connection, proto: string
+    ) {.async: (raises: [CancelledError]).} =
+      defer:
+        await conn.close()
+      while not conn.atEof:
+        let buf =
+          try:
+            await conn.readLp(MaxMsgSize)
+          except LPStreamEOFError:
+            return
+          except LPStreamError as exc:
+            debug "Read error when handling kademlia RPC", conn = conn, err = exc.msg
+            return
+        let msg = Message.decode(buf).valueOr:
+          debug "Failed to decode message", err = error
           return
-        except LPStreamError as exc:
-          debug "Read error when handling kademlia RPC", conn = conn, err = exc.msg
+
+        case msg.msgType
+        of MessageType.findNode:
+          await kad.handleFindNode(conn, msg)
+        of MessageType.putValue:
+          await kad.handlePutValue(conn, msg)
+        of MessageType.getValue:
+          await kad.handleGetValue(conn, msg)
+        of MessageType.addProvider:
+          await kad.handleAddProvider(conn, msg)
+        of MessageType.getProviders:
+          await kad.handleGetProviders(conn, msg)
+        of MessageType.ping:
+          await kad.handlePing(conn, msg)
+        else:
+          error "Unhandled kad-dht message type", msg = msg
           return
-      let msg = Message.decode(buf).valueOr:
-        debug "Failed to decode message", err = error
-        return
-
-      case msg.msgType
-      of MessageType.findNode:
-        await kad.handleFindNode(conn, msg)
-      of MessageType.putValue:
-        await kad.handlePutValue(conn, msg)
-      of MessageType.getValue:
-        await kad.handleGetValue(conn, msg)
-      of MessageType.addProvider:
-        await kad.handleAddProvider(conn, msg)
-      of MessageType.getProviders:
-        await kad.handleGetProviders(conn, msg)
-      of MessageType.ping:
-        await kad.handlePing(conn, msg)
-      else:
-        error "Unhandled kad-dht message type", msg = msg
-        return
   return kad
 
 method start*(kad: KadDHT) {.async: (raises: [CancelledError]).} =

tests/kademlia/test_builder.nim

@@ -11,6 +11,7 @@
 
 import chronos
 import ../../libp2p/[switch, builders]
+import ../../libp2p/protocols/kademlia
 import ../tools/[unittest]
 import ./utils.nim
 
@@ -46,3 +47,35 @@ suite "KadDHT - Builder":
       await allFutures(switch1.stop(), switch2.stop())
     check:
       switch1.ms.handlers[1].protos[0] == "/ipfs/kad/1.0.0"
+
+  asyncTest "Use Kad as a client only":
+    var switch1 = SwitchBuilder
+      .new()
+      .withRng(newRng())
+      .withAddresses(@[MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet()])
+      .withTcpTransport()
+      .withMplex()
+      .withNoise()
+      .withKademlia()
+      .build()
+
+    var switch2 = SwitchBuilder
+      .new()
+      .withRng(newRng())
+      .withAddresses(@[MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet()])
+      .withTcpTransport()
+      .withMplex()
+      .withNoise()
+      .build()
+
+    let kad2 = KadDHT.new(
+      switch2,
+      bootstrapNodes = @[(switch1.peerInfo.peerId, switch1.peerInfo.addrs)],
+      client = true,
+    )
+
+    await allFutures(switch1.start(), switch2.start())
+    defer:
+      await allFutures(switch1.stop(), switch2.stop())
+
+    check (await kad2.putValue(kad2.rtable.selfId, @[1.byte, 2, 3, 4, 5])).isOk()