mirror of https://github.com/status-im/nim-eth.git
Handle packets with selective acks (#451)
* Handle packets with selective acks
This commit is contained in:
KonradStaniec
GitHub
parent
5655bd035c
commit
0cfe7df817
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@ -17,8 +17,10 @@ export results
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const
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minimalHeaderSize = 20
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minimalHeaderSizeWithSelectiveAck = 26
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protocolVersion = 1
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zeroMoment = Moment.init(0, Nanosecond)
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acksArrayLength: uint8 = 4
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type
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PacketType* = enum
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@ -46,8 +48,12 @@ type
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# sequence number the sender of the packet last received in the other direction
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ackNr*: uint16
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SelectiveAckExtension = object
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acks: array[acksArrayLength, byte]
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Packet* = object
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header*: PacketHeaderV1
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eack*: Option[SelectiveAckExtension]
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payload*: seq[uint8]
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TimeStampInfo* = object
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@ -102,10 +108,22 @@ proc encodeHeaderStream(s: var OutputStream, h: PacketHeaderV1) =
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# This should not happen in case of in-memory streams
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raiseAssert e.msg
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proc encodeExtensionStream(s: var OutputStream, e: SelectiveAckExtension) =
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try:
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# writing 0 as there is not further extensions after selectiv ack
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s.write(0'u8)
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s.write(acksArrayLength)
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s.write(e.acks)
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except IOError as e:
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# This should not happen in case of in-memory streams
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raiseAssert e.msg
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proc encodePacket*(p: Packet): seq[byte] =
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var s = memoryOutput().s
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try:
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encodeHeaderStream(s, p.header)
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if (p.eack.isSome()):
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encodeExtensionStream(s, p.eack.unsafeGet())
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if (len(p.payload) > 0):
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s.write(p.payload)
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s.getOutput()
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@ -113,9 +131,9 @@ proc encodePacket*(p: Packet): seq[byte] =
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# This should not happen in case of in-memory streams
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raiseAssert e.msg
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# TODO for now we do not handle extensions
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proc decodePacket*(bytes: openArray[byte]): Result[Packet, string] =
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if len(bytes) < minimalHeaderSize:
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let receivedBytesLength = len(bytes)
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if receivedBytesLength < minimalHeaderSize:
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return err("invalid header size")
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let version = bytes[0] and 0xf
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@ -126,11 +144,16 @@ proc decodePacket*(bytes: openArray[byte]): Result[Packet, string] =
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if not checkedEnumAssign(kind, (bytes[0] shr 4)):
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return err("Invalid message type")
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let extensionByte = bytes[1]
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if (not (extensionByte == 0 or extensionByte == 1)):
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return err("Invalid extension type")
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let header =
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PacketHeaderV1(
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pType: kind,
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version: version,
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extension: bytes[1],
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extension: extensionByte,
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connection_id: fromBytesBE(uint16, bytes.toOpenArray(2, 3)),
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timestamp: fromBytesBE(uint32, bytes.toOpenArray(4, 7)),
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timestamp_diff: fromBytesBE(uint32, bytes.toOpenArray(8, 11)),
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@ -139,13 +162,43 @@ proc decodePacket*(bytes: openArray[byte]): Result[Packet, string] =
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ack_nr: fromBytesBE(uint16, bytes.toOpenArray(18, 19)),
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)
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let payload =
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if (len(bytes) == 20):
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@[]
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else:
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bytes[20..^1]
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if extensionByte == 0:
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# packet without any extensions
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let payload =
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if (receivedBytesLength == minimalHeaderSize):
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@[]
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else:
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bytes[20..^1]
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ok(Packet(header: header, payload: payload))
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return ok(Packet(header: header, eack: none[SelectiveAckExtension](), payload: payload))
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else:
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# packet with selective ack extension
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if (receivedBytesLength < minimalHeaderSizeWithSelectiveAck):
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return err("Packet too short for selective ack extension")
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let nextExtension = bytes[20]
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let extLength = bytes[21]
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# As selective ack is only supported extension the byte for nextExtension
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# must be equal to 0.
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# As for extLength, specificaiton says that it must be at least 4, and in multiples of 4
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# but reference implementation always uses 4 bytes bit mask which makes sense
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# as 4byte bit mask is able to ack 32 packets in the future which is more than enough
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if (nextExtension != 0 or extLength != 4):
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return err("Bad format of selective ack extension")
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let extension = SelectiveAckExtension(
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acks: [bytes[22], bytes[23], bytes[24], bytes[25]]
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)
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let payload =
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if (receivedBytesLength == minimalHeaderSizeWithSelectiveAck):
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@[]
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else:
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bytes[26..^1]
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return ok(Packet(header: header, eack: some(extension), payload: payload))
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proc modifyTimeStampAndAckNr*(packetBytes: var seq[byte], newTimestamp: uint32, newAckNr: uint16) =
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## Modifies timestamp and ack nr of already encoded packets. Those fields should be
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@ -163,7 +216,6 @@ proc synPacket*(seqNr: uint16, rcvConnectionId: uint16, bufferSize: uint32): Pac
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let h = PacketHeaderV1(
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pType: ST_SYN,
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version: protocolVersion,
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# TODO for we do not handle extensions
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extension: 0'u8,
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connectionId: rcvConnectionId,
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timestamp: getMonoTimestamp().timestamp,
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@ -174,14 +226,27 @@ proc synPacket*(seqNr: uint16, rcvConnectionId: uint16, bufferSize: uint32): Pac
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ackNr: 0'u16
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)
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Packet(header: h, payload: @[])
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Packet(header: h, eack: none[SelectiveAckExtension](), payload: @[])
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proc ackPacket*(
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seqNr: uint16,
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sndConnectionId: uint16,
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ackNr: uint16,
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bufferSize: uint32,
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timestampDiff: uint32,
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acksBitmask: Option[array[4, byte]] = none[array[4, byte]]()
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): Packet =
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let (extensionByte, extensionData) =
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if acksBitmask.isSome():
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(1'u8, some(SelectiveAckExtension(acks: acksBitmask.unsafeGet())))
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else:
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(0'u8, none[SelectiveAckExtension]())
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proc ackPacket*(seqNr: uint16, sndConnectionId: uint16, ackNr: uint16, bufferSize: uint32, timestampDiff: uint32): Packet =
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let h = PacketHeaderV1(
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pType: ST_STATE,
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version: protocolVersion,
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# TODO Handle selective acks
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extension: 0'u8,
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extension: extensionByte,
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connectionId: sndConnectionId,
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timestamp: getMonoTimestamp().timestamp,
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timestampDiff: timestampDiff,
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@ -190,7 +255,8 @@ proc ackPacket*(seqNr: uint16, sndConnectionId: uint16, ackNr: uint16, bufferSiz
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ackNr: ackNr
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)
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Packet(header: h, payload: @[])
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Packet(header: h, eack: extensionData, payload: @[])
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proc dataPacket*(
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seqNr: uint16,
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@ -213,7 +279,7 @@ proc dataPacket*(
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ackNr: ackNr
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)
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Packet(header: h, payload: payload)
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Packet(header: h, eack: none[SelectiveAckExtension](), payload: payload)
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proc resetPacket*(seqNr: uint16, sndConnectionId: uint16, ackNr: uint16): Packet =
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let h = PacketHeaderV1(
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@ -231,7 +297,7 @@ proc resetPacket*(seqNr: uint16, sndConnectionId: uint16, ackNr: uint16): Packet
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ackNr: ackNr
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)
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Packet(header: h, payload: @[])
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Packet(header: h, eack: none[SelectiveAckExtension](), payload: @[])
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proc finPacket*(
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seqNr: uint16,
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@ -253,4 +319,4 @@ proc finPacket*(
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ackNr: ackNr
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)
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Packet(header: h, payload: @[])
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Packet(header: h, eack: none[SelectiveAckExtension](), payload: @[])
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@ -7,6 +7,7 @@
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{.used.}
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import
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std/options,
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unittest2,
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../../eth/utp/packets,
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../../eth/keys
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@ -21,8 +22,109 @@ suite "Utp packets encoding/decoding":
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let decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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decoded.isOk()
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synPacket == decoded.get()
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let synPacketDec = decoded.get()
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check:
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synPacketDec == synPacket
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test "Encode/decode fin packet":
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let finPacket = finPacket(5, 10, 20, 30, 40)
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let encoded = encodePacket(finPacket)
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let decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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decoded.isOk()
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let finPacketDec = decoded.get()
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check:
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finPacketDec == finPacket
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test "Encode/decode reset packet":
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let resetPacket = resetPacket(5, 10, 20)
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let encoded = encodePacket(resetPacket)
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let decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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decoded.isOk()
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let resetPacketDec = decoded.get()
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check:
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resetPacketDec == resetPacket
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test "Encode/decode ack packet without extensions":
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let ackPacket = ackPacket(5, 10, 20, 30, 40)
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let encoded = encodePacket(ackPacket)
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let decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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decoded.isOk()
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let ackPacketDec = decoded.get()
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check:
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ackPacketDec == ackPacket
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test "Encode/decode ack packet with extensions":
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let bitMask: array[4, byte] = [1'u8, 2, 3, 4]
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let ackPacket = ackPacket(5, 10, 20, 30, 40, some(bitMask))
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let encoded = encodePacket(ackPacket)
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let decoded = decodePacket(encoded)
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check:
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len(encoded) == 26
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decoded.isOk()
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let ackPacketDec = decoded.get()
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check:
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ackPacketDec == ackPacket
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ackPacketDec.eack.isSome()
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test "Fail to decode packet with malformed extensions":
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let bitMask: array[4, byte] = [1'u8, 2, 3, 4]
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let ackPacket = ackPacket(5, 10, 20, 30, 40, some(bitMask))
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var encoded1 = encodePacket(ackPacket)
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# change nextExtension to non zero
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encoded1[20] = 1
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let err1 = decodePacket(encoded1)
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check:
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err1.isErr()
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err1.error() == "Bad format of selective ack extension"
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var encoded2 = encodePacket(ackPacket)
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# change len of extension to value different than 4
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encoded2[21] = 7
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let err2 = decodePacket(encoded2)
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check:
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err2.isErr()
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err2.error() == "Bad format of selective ack extension"
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var encoded3 = encodePacket(ackPacket)
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# delete last byte, now packet is to short
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encoded3.del(encoded3.high)
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let err3 = decodePacket(encoded3)
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check:
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err3.isErr()
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err3.error() == "Packet too short for selective ack extension"
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var encoded4 = encodePacket(ackPacket)
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# change change extension field to something other than 0 or 1
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encoded4[1] = 2
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let err4 = decodePacket(encoded4)
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check:
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err4.isErr()
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err4.error() == "Invalid extension type"
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test "Decode state packet":
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# Packet obtained by interaction with c reference implementation
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