add DHT storage (addValue/getValue) functionality

this is a minimal implementation, with lots of
work still needed.

Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>

libp2pdht/dht.nim

@@ -1,4 +1,6 @@
 import
-  ./dht/[providers_encoding, providers_messages]
+  ./dht/[providers_encoding, providers_messages],
+  ./dht/[value_encoding, value_messages]
 
-export providers_encoding, providers_messages
+export providers_encoding, providers_messages
+export value_encoding, value_messages

libp2pdht/dht/value_encoding.nim

@@ -0,0 +1,77 @@
+import
+  ../discv5/[node],
+  libp2p/protobuf/minprotobuf,
+  ./value_messages
+
+func getField(pb: ProtoBuffer, field: int,
+               nid: var NodeId): ProtoResult[bool] {.inline.} =
+  ## Read ``NodeId`` from ProtoBuf's message and validate it
+  var buffer: seq[byte]
+  let res = ? pb.getField(field, buffer)
+  if not(res):
+    ok(false)
+  else:
+    nid = readUintBE[256](buffer)
+    ok(true)
+
+func write(pb: var ProtoBuffer, field: int, nid: NodeId) =
+  ## Write NodeId value ``nodeid`` to object ``pb`` using ProtoBuf's encoding.
+  write(pb, field, nid.toBytesBE())
+
+proc decode*(
+  T: typedesc[AddValueMessage],
+  buffer: openArray[byte]): Result[AddValueMessage, ProtoError] =
+
+  let pb = initProtoBuffer(buffer)
+  var msg = AddValueMessage()
+
+  ? pb.getRequiredField(1, msg.cId)
+  ? pb.getRequiredField(2, msg.value)
+
+  ok(msg)
+
+proc encode*(msg: AddValueMessage): seq[byte] =
+  var pb = initProtoBuffer()
+
+  pb.write(1, msg.cId)
+  pb.write(2, msg.value)
+
+  pb.finish()
+  pb.buffer
+
+proc decode*(
+  T: typedesc[GetValueMessage],
+  buffer: openArray[byte]): Result[GetValueMessage, ProtoError] =
+
+  let pb = initProtoBuffer(buffer)
+  var msg = GetValueMessage()
+
+  ? pb.getRequiredField(1, msg.cId)
+
+  ok(msg)
+
+proc encode*(msg: GetValueMessage): seq[byte] =
+  var pb = initProtoBuffer()
+
+  pb.write(1, msg.cId)
+
+  pb.finish()
+  pb.buffer
+
+proc decode*(
+  T: typedesc[ValueMessage],
+  buffer: openArray[byte]): Result[ValueMessage, ProtoError] =
+
+  let pb = initProtoBuffer(buffer)
+  var msg = ValueMessage()
+  ? pb.getRequiredField(1, msg.value)
+
+  ok(msg)
+
+proc encode*(msg: ValueMessage): seq[byte] =
+  var pb = initProtoBuffer()
+
+  pb.write(1, msg.value)
+
+  pb.finish()
+  pb.buffer

libp2pdht/dht/value_messages.nim

@@ -0,0 +1,14 @@
+import
+  ../discv5/[node]
+
+type
+  AddValueMessage* = object
+    cId*: NodeId
+    value*: seq[byte]
+
+  GetValueMessage* = object
+    cId*: NodeId
+
+  ValueMessage* = object
+    #total*: uint32
+    value*: seq[byte]

libp2pdht/private/eth/p2p/discoveryv5/messages.nim

@@ -17,9 +17,11 @@ import
   bearssl/rand,
   ./spr,
   ./node,
-  ../../../../dht/providers_messages
+  ../../../../dht/providers_messages,
+  ../../../../dht/value_messages
 
 export providers_messages
+export value_messages
 
 type
   MessageKind* {.pure.} = enum
@@ -41,6 +43,9 @@ type
     addProvider = 0x0B
     getProviders = 0x0C
     providers = 0x0D
+    addValue = 0x0E
+    getValue = 0x0F
+    respValue = 0x10
     findNodeFast = 0x83
 
   RequestId* = object
@@ -79,7 +84,8 @@ type
 
   SomeMessage* = PingMessage or PongMessage or FindNodeMessage or NodesMessage or
     TalkReqMessage or TalkRespMessage or AddProviderMessage or GetProvidersMessage or
-    ProvidersMessage or FindNodeFastMessage
+    ProvidersMessage or FindNodeFastMessage or
+    AddValueMessage or GetValueMessage or ValueMessage
 
   Message* = object
     reqId*: RequestId
@@ -112,6 +118,12 @@ type
       getProviders*: GetProvidersMessage
     of providers:
       provs*: ProvidersMessage
+    of addValue:
+      addValue*: AddValueMessage
+    of getValue:
+      getValue*: GetValueMessage
+    of respValue:
+      value*: ValueMessage
     else:
       discard
 
@@ -126,6 +138,9 @@ template messageKind*(T: typedesc[SomeMessage]): MessageKind =
   elif T is AddProviderMessage: MessageKind.addProvider
   elif T is GetProvidersMessage: MessageKind.getProviders
   elif T is ProvidersMessage: MessageKind.providers
+  elif T is AddValueMessage: MessageKind.addValue
+  elif T is GetValueMessage: MessageKind.getValue
+  elif T is ValueMessage: MessageKind.respValue
 
 proc hash*(reqId: RequestId): Hash =
   hash(reqId.id)

libp2pdht/private/eth/p2p/discoveryv5/messages_encoding.nim

@@ -14,7 +14,8 @@ import
   libp2p/routing_record,
   libp2p/signed_envelope,
   "."/[messages, spr, node],
-  ../../../../dht/providers_encoding
+  ../../../../dht/providers_encoding,
+  ../../../../dht/value_encoding
 
 from stew/objects import checkedEnumAssign
 
@@ -434,6 +435,30 @@ proc decodeMessage*(body: openArray[byte]): DecodeResult[Message] =
     else:
       return err("Unable to decode ProvidersMessage")
 
+  of addValue:
+    let res = AddValueMessage.decode(encoded)
+    if res.isOk:
+      message.addValue = res.get
+      return ok(message)
+    else:
+      return err "Unable to decode AddValueMessage"
+
+  of getValue:
+    let res = GetValueMessage.decode(encoded)
+    if res.isOk:
+      message.getValue = res.get
+      return ok(message)
+    else:
+      return err("Unable to decode GetValueMessage")
+
+  of respValue:
+    let res = ValueMessage.decode(encoded)
+    if res.isOk:
+      message.value = res.get
+      return ok(message)
+    else:
+      return err("Unable to decode ValueMessage")
+
   of regTopic, ticket, regConfirmation, topicQuery:
     # We just pass the empty type of this message without attempting to
     # decode, so that the protocol knows what was received.

libp2pdht/private/eth/p2p/discoveryv5/protocol.nim

@@ -172,6 +172,7 @@ type
     talkProtocols*: Table[seq[byte], TalkProtocol] # TODO: Table is a bit of
     rng*: ref HmacDrbgContext
     providers: ProvidersManager
+    valueStore: Table[NodeId, seq[byte]]
 
   TalkProtocolHandler* = proc(p: TalkProtocol, request: seq[byte], fromId: NodeId, fromUdpAddress: Address): seq[byte]
     {.gcsafe, raises: [Defect].}
@@ -397,6 +398,38 @@ proc handleGetProviders(
   let response = ProvidersMessage(total: 1, provs: provs.get)
   d.sendResponse(fromId, fromAddr, response, reqId)
 
+proc addValueLocal(p: Protocol, cId: NodeId, value: seq[byte]) {.async.} =
+  trace "adding value to local db", n = p.localNode, cId, value
+
+  p.valueStore[cId] = value
+
+proc handleAddValue(
+  d: Protocol,
+  fromId: NodeId,
+  fromAddr: Address,
+  addValue: AddValueMessage,
+  reqId: RequestId) =
+  asyncSpawn d.addValueLocal(addValue.cId, addValue.value)
+
+proc handleGetValue(
+  d: Protocol,
+  fromId: NodeId,
+  fromAddr: Address,
+  getValue: GetValueMessage,
+  reqId: RequestId) {.async.} =
+
+  try:
+    let value = d.valueStore[getValue.cId]
+    trace "retrieved value from local db", n = d.localNode, cID = getValue.cId, value
+    ##TODO: handle multiple messages?
+    let response = ValueMessage(value: value)
+    d.sendResponse(fromId, fromAddr, response, reqId)
+
+  except KeyError:
+    # should we respond here? I would say so
+    trace "no value in local db", n = d.localNode, cID = getValue.cId
+    # TODO: add noValue response
+
 proc handleMessage(d: Protocol, srcId: NodeId, fromAddr: Address,
     message: Message) =
   case message.kind
@@ -419,6 +452,13 @@ proc handleMessage(d: Protocol, srcId: NodeId, fromAddr: Address,
   of getProviders:
     discovery_message_requests_incoming.inc()
     asyncSpawn d.handleGetProviders(srcId, fromAddr, message.getProviders, message.reqId)
+  of addValue:
+    discovery_message_requests_incoming.inc()
+    #discovery_message_requests_incoming.inc(labelValues = ["no_response"])
+    d.handleAddValue(srcId, fromAddr, message.addValue, message.reqId)
+  of getValue:
+    discovery_message_requests_incoming.inc()
+    asyncSpawn d.handleGetValue(srcId, fromAddr, message.getValue, message.reqId)
   of regTopic, topicQuery:
     discovery_message_requests_incoming.inc()
     discovery_message_requests_incoming.inc(labelValues = ["no_response"])
@@ -807,6 +847,92 @@ proc getProviders*(
 
   return ok res
 
+proc addValue*(
+    d: Protocol,
+    cId: NodeId,
+    value: seq[byte]): Future[seq[Node]] {.async.} =
+
+  var res = await d.lookup(cId)
+  trace "lookup returned:", res
+  # TODO: lookup is specified as not returning local, even if that is the closest. Is this OK?
+  if res.len == 0:
+      res.add(d.localNode)
+  for toNode in res:
+    if toNode != d.localNode:
+      let reqId = RequestId.init(d.rng[])
+      d.sendRequest(toNode, AddValueMessage(cId: cId, value: value), reqId)
+    else:
+      asyncSpawn d.addValueLocal(cId, value)
+
+  return res
+
+proc sendGetValue(d: Protocol, toNode: Node,
+                       cId: NodeId): Future[DiscResult[ValueMessage]]
+                       {.async.} =
+  let msg = GetValueMessage(cId: cId)
+  trace "sendGetValue", toNode, msg
+
+  let
+    resp = await d.waitResponse(toNode, msg)
+
+  if resp.isSome():
+    if resp.get().kind == MessageKind.respValue:
+      d.routingTable.setJustSeen(toNode)
+      return ok(resp.get().value)
+    else:
+      # TODO: do we need to do something when there is an invalid response?
+      d.replaceNode(toNode)
+      discovery_message_requests_outgoing.inc(labelValues = ["invalid_response"])
+      return err("Invalid response to GetValue message")
+  else:
+    # TODO: do we need to do something when there is no response?
+    d.replaceNode(toNode)
+    discovery_message_requests_outgoing.inc(labelValues = ["no_response"])
+    return err("GetValue response message not received in time")
+
+proc getValue*(
+    d: Protocol,
+    cId: NodeId,
+    timeout: Duration = 5000.milliseconds # TODO: not used?
+  ): Future[DiscResult[seq[byte]]] {.async.} =
+
+  # # What value do we know about?
+  # var res = await d.getProvidersLocal(cId, maxitems)
+  # trace "local providers:", prov = res.mapIt(it)
+
+  let nodesNearby = await d.lookup(cId)
+  trace "nearby:", nodesNearby
+  var providersFut: seq[Future[DiscResult[ValueMessage]]]
+  for n in nodesNearby:
+    if n != d.localNode:
+      providersFut.add(d.sendGetValue(n, cId))
+
+  while providersFut.len > 0:
+    let providersMsg = await one(providersFut)
+    # trace "Got providers response", providersMsg
+
+    let index = providersFut.find(providersMsg)
+    if index != -1:
+      providersFut.del(index)
+
+    let providersMsg2 = await providersMsg
+
+    let providersMsgRes = providersMsg.read
+    if providersMsgRes.isOk:
+      let value = providersMsgRes.get.value
+      var res = value
+      # TODO: validate result before accepting as the right one
+      # TODO: cancel pending futures!
+      return ok res
+    else:
+      error "Sending of GetValue message failed", error = providersMsgRes.error
+      # TODO: should we consider this as an error result if all GetProviders
+      # requests fail??
+
+  trace "getValue returned no result", cId
+
+  return err "getValue failed"
+
 proc query*(d: Protocol, target: NodeId, k = BUCKET_SIZE): Future[seq[Node]]
     {.async.} =
   ## Query k nodes for the given target, returns all nodes found, including the