344 lines
12 KiB
Nim
344 lines
12 KiB
Nim
# Nimbus
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# Copyright (c) 2022 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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{.push raises: [Defect].}
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import
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std/sequtils,
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chronos, stew/[byteutils, leb128], chronicles,
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eth/utp/utp_discv5_protocol,
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# even though utp_discv5_protocol exports this, import is still needed,
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# perhaps protocol.Protocol type of usage?
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eth/p2p/discoveryv5/protocol,
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./messages
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export utp_discv5_protocol
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logScope:
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topics = "portal_stream"
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const
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utpProtocolId* = "utp".toBytes()
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defaultConnectionTimeout = 5.seconds
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defaultContentReadTimeout = 2.seconds
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# TalkReq message is used as transport for uTP. It is assumed here that Portal
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# protocol messages were exchanged before sending uTP over discv5 data. This
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# means that a session is established and that the discv5 messages send are
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# discv5 ordinary message packets, for which below calculation applies.
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talkReqOverhead =
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16 + # IV size
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55 + # header size
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1 + # talkReq msg id
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3 + # rlp encoding outer list, max length will be encoded in 2 bytes
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9 + # request id (max = 8) + 1 byte from rlp encoding byte string
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len(utpProtocolId) + 1 + # + 1 is necessary due to rlp encoding of byte string
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3 + # rlp encoding response byte string, max length in 2 bytes
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16 # HMAC
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utpHeaderOverhead = 20
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maxUtpPayloadSize* = maxDiscv5PacketSize - talkReqOverhead - utpHeaderOverhead
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type
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ContentRequest = object
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connectionId: uint16
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nodeId: NodeId
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content: seq[byte]
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timeout: Moment
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ContentOffer = object
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connectionId: uint16
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nodeId: NodeId
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contentKeys: ContentKeysList
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timeout: Moment
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ContentHandlerCallback* = proc(
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stream: PortalStream, contentKeys: ContentKeysList,
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content: seq[seq[byte]]) {.gcsafe, raises: [Defect].}
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PortalStream* = ref object
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transport: UtpDiscv5Protocol
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# TODO:
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# Decide on what's the better collection to use and set some limits in them
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# on how many uTP transfers allowed to happen concurrently.
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# Either set some limit, and drop whatever comes next. Unsure how to
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# communicate that with the peer however. Or have some more async waiting
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# until a spot becomes free, like with an AsyncQueue. Although the latter
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# probably can not be used here directly. This system however does needs
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# some agreement on timeout values of how long a uTP socket may be
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# "listening" before it times out because of inactivity.
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# Or, depending on the direction, it might also depend on the time out
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# values of the discovery v5 talkresp message.
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# TODO: Should the content key also be stored to be able to validate the
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# received data?
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contentRequests: seq[ContentRequest]
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contentOffers: seq[ContentOffer]
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connectionTimeout: Duration
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contentReadTimeout*: Duration
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rng: ref HmacDrbgContext
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udata: pointer
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contentHandler: ContentHandlerCallback
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proc pruneAllowedConnections(stream: PortalStream) =
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# Prune requests and offers that didn't receive a connection request
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# before `connectionTimeout`.
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let now = Moment.now()
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stream.contentRequests.keepIf(proc(x: ContentRequest): bool =
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x.timeout > now)
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stream.contentOffers.keepIf(proc(x: ContentOffer): bool =
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x.timeout > now)
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proc getUserData*[T](stream: PortalStream): T =
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## Obtain user data stored in ``stream`` object.
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cast[T](stream.udata)
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proc addContentOffer*(
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stream: PortalStream, nodeId: NodeId, contentKeys: ContentKeysList): Bytes2 =
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stream.pruneAllowedConnections()
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# TODO: Should we check if `NodeId` & `connectionId` combo already exists?
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# What happens if we get duplicates?
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var connectionId: Bytes2
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stream.rng[].generate(connectionId)
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# uTP protocol uses BE for all values in the header, incl. connection id.
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let id = uint16.fromBytesBE(connectionId)
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let contentOffer = ContentOffer(
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connectionId: id,
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nodeId: nodeId,
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contentKeys: contentKeys,
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timeout: Moment.now() + stream.connectionTimeout)
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stream.contentOffers.add(contentOffer)
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return connectionId
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proc addContentRequest*(
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stream: PortalStream, nodeId: NodeId, content: seq[byte]): Bytes2 =
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stream.pruneAllowedConnections()
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# TODO: Should we check if `NodeId` & `connectionId` combo already exists?
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# What happens if we get duplicates?
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var connectionId: Bytes2
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stream.rng[].generate(connectionId)
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# uTP protocol uses BE for all values in the header, incl. connection id.
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let id = uint16.fromBytesBE(connectionId)
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let contentRequest = ContentRequest(
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connectionId: id,
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nodeId: nodeId,
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content: content,
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timeout: Moment.now() + stream.connectionTimeout)
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stream.contentRequests.add(contentRequest)
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return connectionId
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proc connectTo*(
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stream: PortalStream,
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nodeAddress: NodeAddress,
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connectionId: uint16):
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Future[Result[UtpSocket[NodeAddress], string]] {.async.} =
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let connectFut = stream.transport.connectTo(nodeAddress, connectionId)
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# using yield, not await, as await does not play nice with cancellation
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# interacting with async procs which allocates some resource
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yield connectFut
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var socketRes: ConnectionResult[NodeAddress]
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if connectFut.completed():
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socketRes = connectFut.read()
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else:
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raise connectFut.error
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if socketRes.isErr():
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case socketRes.error.kind
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of SocketAlreadyExists:
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# This means that there is already a socket to this nodeAddress with given
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# connection id. It probably means that a peersent us a connection id
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# which is already in use..
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# For now just fail the connection and return an error. Another strategy
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# to consider would be to check what is the connection status, and then
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# re-use it, or close it and retry connection.
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let msg = "Socket to " & $nodeAddress & "with connection id: " &
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$connectionId & " already exists"
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return err(msg)
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of ConnectionTimedOut:
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# Another strategy for handling this error would be to retry connecting a
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# few times before giving up. But we know (as we control the uTP impl)
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# that this error will only occur when a SYN packet was re-sent 3 times
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# and failed to be acked. This should be enough of indication that the
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# remote host is not reachable.
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let msg = "uTP timeout while trying to connect to " & $nodeAddress
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return err(msg)
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let socket = socketRes.get()
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return ok(socket)
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proc writeContentRequest(
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socket: UtpSocket[NodeAddress], stream: PortalStream,
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request: ContentRequest) {.async.} =
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let dataWritten = await socket.write(request.content)
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if dataWritten.isErr():
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debug "Error writing requested data", error = dataWritten.error
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await socket.closeWait()
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proc readVarint(socket: UtpSocket[NodeAddress]):
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Future[Opt[uint32]] {.async.} =
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var
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buffer: array[5, byte]
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for i in 0..<len(buffer):
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let dataRead = await socket.read(1)
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if dataRead.len() == 0:
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return err()
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buffer[i] = dataRead[0]
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let (lenU32, bytesRead) = fromBytes(uint32, buffer.toOpenArray(0, i), Leb128)
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if bytesRead > 0:
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return ok(lenU32)
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elif bytesRead == 0:
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continue
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else:
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return err()
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proc readContentItem(socket: UtpSocket[NodeAddress]):
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Future[Opt[seq[byte]]] {.async.} =
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let len = await socket.readVarint()
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if len.isOk():
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let contentItem = await socket.read(len.get())
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if contentItem.len() == len.get().int:
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return ok(contentItem)
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else:
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return err()
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else:
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return err()
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proc readContentOffer(
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socket: UtpSocket[NodeAddress], stream: PortalStream,
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offer: ContentOffer) {.async.} =
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# Read number of content items according to amount of ContentKeys accepted.
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# This will either end with a FIN, or because the read action times out or
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# because the number of expected items was read (if this happens and no FIN
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# was received yet, a FIN will be send from this side).
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# None of this means that the contentItems are valid, further validation is
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# required.
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# Socket will be closed when this call ends.
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# TODO: Currently reading from the socket 1 item at a time, and validating
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# items at later time. Uncertain what is best approach here (mostly from a
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# security PoV), e.g. other options such as reading all content from socket at
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# once, then processing the individual content items. Or reading and
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# validating one per time.
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let amount = offer.contentKeys.len()
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var contentItems: seq[seq[byte]]
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for i in 0..<amount:
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let contentItemFut = socket.readContentItem()
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if await contentItemFut.withTimeout(stream.contentReadTimeout):
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let contentItem = contentItemFut.read
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if contentItem.isOk():
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contentItems.add(contentItem.get())
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else:
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# Invalid data, stop reading content, but still process data received
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# so far.
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debug "Reading content item failed, content offer failed"
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break
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else:
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# Read timed out, stop further reading, but still process data received
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# so far.
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debug "Reading data from socket timed out, content offer failed"
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break
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if socket.atEof():
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# Destroy socket and not closing as we already received FIN. Closing would
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# send also a FIN from our side, see also:
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# https://github.com/status-im/nim-eth/blob/b2dab4be0839c95ca2564df9eacf81995bf57802/eth/utp/utp_socket.nim#L1223
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await socket.destroyWait()
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else:
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# This means FIN didn't arrive yet, perhaps it got dropped but it might also
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# be still in flight. Closing the socket (= sending FIN) ourselves.
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# Not waiting here for its ACK however, so no `closeWait`
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socket.close()
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if not stream.contentHandler.isNil():
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stream.contentHandler(stream, offer.contentKeys, contentItems)
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proc new*(
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T: type PortalStream,
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contentHandler: ContentHandlerCallback,
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udata: ref,
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connectionTimeout = defaultConnectionTimeout,
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contentReadTimeout = defaultContentReadTimeout,
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rng = newRng()): T =
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GC_ref(udata)
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let
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stream = PortalStream(
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contentHandler: contentHandler,
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udata: cast[pointer](udata),
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connectionTimeout: connectionTimeout,
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contentReadTimeout: contentReadTimeout,
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rng: rng)
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stream
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func setTransport*(stream: PortalStream, transport: UtpDiscv5Protocol) =
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stream.transport = transport
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# TODO: I think I'd like it more if we weren't to capture the stream.
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proc registerIncomingSocketCallback*(
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streams: seq[PortalStream]): AcceptConnectionCallback[NodeAddress] =
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return (
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proc(server: UtpRouter[NodeAddress], socket: UtpSocket[NodeAddress]): Future[void] =
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for stream in streams:
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# Note: Connection id of uTP SYN is different from other packets, it is
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# actually the peers `send_conn_id`, opposed to `receive_conn_id` for all
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# other packets.
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for i, request in stream.contentRequests:
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if request.connectionId == socket.connectionId and
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request.nodeId == socket.remoteAddress.nodeId:
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let fut = socket.writeContentRequest(stream, request)
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stream.contentRequests.del(i)
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return fut
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for i, offer in stream.contentOffers:
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if offer.connectionId == socket.connectionId and
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offer.nodeId == socket.remoteAddress.nodeId:
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let fut = socket.readContentOffer(stream, offer)
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stream.contentOffers.del(i)
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return fut
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# TODO: Is there a scenario where this can happen,
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# considering `allowRegisteredIdCallback`? If not, doAssert?
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var fut = newFuture[void]("fluffy.AcceptConnectionCallback")
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fut.complete()
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return fut
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)
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proc allowedConnection(
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stream: PortalStream, address: NodeAddress, connectionId: uint16): bool =
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return
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stream.contentRequests.any(
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proc (x: ContentRequest): bool =
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x.connectionId == connectionId and x.nodeId == address.nodeId) or
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stream.contentOffers.any(
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proc (x: ContentOffer): bool =
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x.connectionId == connectionId and x.nodeId == address.nodeId)
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proc allowRegisteredIdCallback*(
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streams: seq[PortalStream]): AllowConnectionCallback[NodeAddress] =
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return (
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proc(r: UtpRouter[NodeAddress], remoteAddress: NodeAddress, connectionId: uint16): bool =
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for stream in streams:
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# stream.pruneAllowedConnections()
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if allowedConnection(stream, remoteAddress, connectionId):
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return true
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)
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