mirror of https://github.com/status-im/nim-eth.git
Improve uTP decoded packet logs + style and comment clean-up (#593)
* Improve uTP decoded packet logs + style and comment clean-up * Don't test for the exact error strings in uTP decode + clean-up
This commit is contained in:
Kim De Mey
GitHub
parent
72c9858927
commit
29b14749fa
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@ -1,9 +1,12 @@
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# Copyright (c) 2020-2021 Status Research & Development GmbH
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# Copyright (c) 2020-2023 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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# uTP packet format as specified in:
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# https://www.bittorrent.org/beps/bep_0029.html
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{.push raises: [Defect].}
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import
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@ -37,14 +40,9 @@ type
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extension*: uint8
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connectionId*: uint16
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timestamp*: MicroSeconds
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# This is the difference between the local time, at the time the last packet
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# was received, and the timestamp in this last received packet
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timestampDiff*: MicroSeconds
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# The window size is the number of bytes currently in-flight, i.e. sent but not acked
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# When sending packets, this should be set to the number of bytes left in the socket's receive buffer.
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wndSize*: uint32
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seqNr*: uint16
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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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@ -59,22 +57,21 @@ type
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moment*: Moment
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timestamp*: uint32
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# Important timing assumptions for utp protocol here:
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# Important timing assumptions for uTP protocol here:
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# 1. Microsecond precisions
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# 2. Monotonicity
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# Reference lib have a lot of checks to assume that this is monotonic on
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# Reference lib has a lot of checks to assume that this is monotonic on
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# every system, and warnings when monotonic clock is not available.
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proc getMonoTimestamp*(): TimeStampInfo =
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let currentMoment = Moment.now()
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# Casting this value from int64 to uin32, my lead to some sudden spikes in
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# timestamp numeric values i.e it is possible that timestamp can suddenly change
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# from 4294967296 to for example 10, this may lead to sudden spikes in
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# calculated delays
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# uTP implementation is resistant to those spikes are as it keeps history of
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# few last delays on uses smallest one for calculating ledbat window.
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# so any outlier huge value will be ignored
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#
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# Casting this value from int64 to uint32, may lead to some sudden spikes in
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# timestamp numeric values, i.e it is possible that the timestamp will
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# suddenly change from 4294967296 to for example 10. This may lead to sudden
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# spikes in calculated delays.
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# The uTP implementation is resistant to those spikes are as it keeps a
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# history of several last delays and uses the smallest one for calculating
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# the ledbat window, thus any outlier value will be ignored.
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let timestamp = uint32((currentMoment - zeroMoment).microseconds())
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TimeStampInfo(moment: currentMoment, timestamp: timestamp)
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@ -86,7 +83,7 @@ proc randUint16*(rng: var HmacDrbgContext): uint16 =
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proc randUint32*(rng: var HmacDrbgContext): uint32 =
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uint32(rand(rng, int(high(uint32))))
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proc encodeTypeVer(h: PacketHeaderV1): uint8 =
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func encodeTypeVer(h: PacketHeaderV1): uint8 =
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var typeVer = 0'u8
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let typeOrd = uint8(ord(h.pType))
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typeVer = (typeVer and 0xf0) or (h.version and 0xf)
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@ -109,7 +106,7 @@ proc encodeHeaderStream(s: var OutputStream, h: PacketHeaderV1) =
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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 selective ack
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# writing always 0 as there are no other extensions (only selective 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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@ -130,14 +127,14 @@ 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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proc decodePacket*(bytes: openArray[byte]): Result[Packet, string] =
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func decodePacket*(bytes: openArray[byte]): Result[Packet, string] =
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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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return err("Invalid header size")
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let version = bytes[0] and 0xf
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if version != protocolVersion:
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return err("invalid packet version")
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return err("Invalid packet version")
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var kind: PacketType
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if not checkedEnumAssign(kind, (bytes[0] shr 4)):
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@ -162,30 +159,35 @@ proc decodePacket*(bytes: openArray[byte]): Result[Packet, string] =
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)
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if extensionByte == 0:
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# packet without any extensions
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# packet without 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[minimalHeaderSize..^1]
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return ok(Packet(header: header, eack: none[SelectiveAckExtension](), payload: payload))
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return ok(Packet(
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header: header,
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eack: none[SelectiveAckExtension](),
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payload: payload))
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else:
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# packet with selective ack extension
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# packet with the 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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return err("Packet too short for selective ack extension: " &
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"len = " & $receivedBytesLength)
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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, specification 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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# The byte for nextExtension must be 0 as selective ack is currently the
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# only supported extension.
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# For extLength, the specification states that it must be at least 4, and
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# in multiples of 4. However, the reference implementation always uses a 4
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# bytes bit mask, which makes sense as a 4 byte bit mask is able to ack
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# 32 packets in the future, which is sounds 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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return err("Bad format of selective ack extension: " &
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"extension = " & $nextExtension & " len = " & $extLength)
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let extension = SelectiveAckExtension(
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acks: toArray(4, bytes.toOpenArray(22, 25))
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@ -199,19 +201,21 @@ proc decodePacket*(bytes: openArray[byte]): Result[Packet, string] =
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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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## filled right before sending, so when re-sending the packet we would like to update
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## it without decoding and re-encoding the packet once again
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proc modifyTimeStampAndAckNr*(
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packetBytes: var seq[byte], newTimestamp: uint32, newAckNr: uint16) =
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## Modifies timestamp and ack nr of already encoded packets. These fields
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## must be filled right before sending, so when re-sending the packet they
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## can be updated without decoding and re-encoding the packet.
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doAssert(len(packetBytes) >= minimalHeaderSize)
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packetBytes[4..7] = toBytesBE(newTimestamp)
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packetBytes[18..19] = toBytesBE(newAckNr)
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# connectionId - should be random not already used number
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# bufferSize - should be pre configured initial buffer size for socket
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# SYN packets are special, and should have the receive ID in the connid field,
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# instead of conn_id_send.
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proc synPacket*(seqNr: uint16, rcvConnectionId: uint16, bufferSize: uint32): Packet =
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proc synPacket*(
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seqNr: uint16, rcvConnectionId: uint16, bufferSize: uint32): Packet =
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# rcvConnectionId - should be a random, not already used, number
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# bufferSize - should be a pre-configured initial buffer size for the socket
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# SYN packets are special and have the conn_id_recv in the conn_id field,
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# instead of conn_id_send.
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let h = PacketHeaderV1(
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pType: ST_SYN,
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version: protocolVersion,
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@ -221,8 +225,7 @@ proc synPacket*(seqNr: uint16, rcvConnectionId: uint16, bufferSize: uint32): Pac
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timestampDiff: 0'u32,
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wndSize: bufferSize,
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seqNr: seqNr,
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# Initially we did not receive any acks
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ackNr: 0'u16
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ackNr: 0'u16 # At start, no acks have been received
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)
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Packet(header: h, eack: none[SelectiveAckExtension](), payload: @[])
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@ -267,8 +270,7 @@ proc dataPacket*(
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let h = PacketHeaderV1(
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pType: ST_DATA,
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version: protocolVersion,
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# data packets always have extension field set to 0
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extension: 0'u8,
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extension: 0'u8, # data packets always have extension field set to 0
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connectionId: sndConnectionId,
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timestamp: getMonoTimestamp().timestamp,
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timestampDiff: timestampDiff,
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@ -279,16 +281,16 @@ proc dataPacket*(
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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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proc resetPacket*(
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seqNr: uint16, sndConnectionId: uint16, ackNr: uint16): Packet =
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let h = PacketHeaderV1(
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pType: ST_RESET,
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version: protocolVersion,
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# data packets always have extension field set to 0
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extension: 0'u8,
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extension: 0'u8, # reset packets always have extension field set to 0
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connectionId: sndConnectionId,
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timestamp: getMonoTimestamp().timestamp,
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# reset packet informs remote about lack of state for given connection, therefore
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# we do not inform remote about its delay.
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# reset packet informs remote about lack of state for given connection,
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# therefore the remote is not informed about its delay.
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timestampDiff: 0,
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wndSize: 0,
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seqNr: seqNr,
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@ -307,8 +309,7 @@ proc finPacket*(
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let h = PacketHeaderV1(
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pType: ST_FIN,
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version: protocolVersion,
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# fin packets always have extension field set to 0
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extension: 0'u8,
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extension: 0'u8, # fin packets always have extension field set to 0
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connectionId: sndConnectionId,
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timestamp: getMonoTimestamp().timestamp,
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timestampDiff: timestampDiff,
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@ -1,4 +1,4 @@
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# Copyright (c) 2020-2021 Status Research & Development GmbH
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# Copyright (c) 2020-2023 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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@ -14,9 +14,10 @@ import
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suite "uTP Packet Encoding":
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test "Encode/decode SYN packet":
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let synPacket = synPacket(5, 10, 20)
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let encoded = encodePacket(synPacket)
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let decoded = decodePacket(encoded)
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let
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synPacket = synPacket(5, 10, 20)
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encoded = encodePacket(synPacket)
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decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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@ -24,13 +25,13 @@ suite "uTP Packet Encoding":
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let synPacketDec = decoded.get()
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check:
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synPacketDec == synPacket
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check 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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let
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finPacket = finPacket(5, 10, 20, 30, 40)
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encoded = encodePacket(finPacket)
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decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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@ -38,13 +39,13 @@ suite "uTP Packet Encoding":
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let finPacketDec = decoded.get()
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check:
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finPacketDec == finPacket
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check 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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let
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resetPacket = resetPacket(5, 10, 20)
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encoded = encodePacket(resetPacket)
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decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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@ -52,13 +53,13 @@ suite "uTP Packet Encoding":
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let resetPacketDec = decoded.get()
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check:
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resetPacketDec == resetPacket
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check 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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let
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ackPacket = ackPacket(5, 10, 20, 30, 40)
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encoded = encodePacket(ackPacket)
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decoded = decodePacket(encoded)
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check:
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len(encoded) == 20
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@ -66,14 +67,14 @@ suite "uTP Packet Encoding":
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let ackPacketDec = decoded.get()
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check:
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ackPacketDec == ackPacket
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check 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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let
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bitMask: array[4, byte] = [1'u8, 2, 3, 4]
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ackPacket = ackPacket(5, 10, 20, 30, 40, some(bitMask))
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encoded = encodePacket(ackPacket)
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decoded = decodePacket(encoded)
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check:
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len(encoded) == 26
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@ -89,38 +90,29 @@ suite "uTP Packet Encoding":
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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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block: # nextExtension to non zero
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var encoded = encodePacket(ackPacket)
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encoded[20] = 1
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let err = decodePacket(encoded)
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check err.isErr()
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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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block: # len of extension to value different than 4
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var encoded = encodePacket(ackPacket)
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encoded[21] = 7
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let err = decodePacket(encoded)
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check err.isErr()
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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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block: # delete last byte, now packet is too short
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var encoded = encodePacket(ackPacket)
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encoded.del(encoded.high)
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let err = decodePacket(encoded)
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check err.isErr()
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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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block: # change extension field to something other than 0 or 1
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var encoded = encodePacket(ackPacket)
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encoded[1] = 2
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let err = decodePacket(encoded)
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check: err.isErr()
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test "Decode STATE packet":
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# Packet obtained by interaction with c reference implementation
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@ -129,8 +121,7 @@ suite "uTP Packet Encoding":
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0x0, 0x0, 0x0, 0x10, 0x0, 0x0, 0x41, 0xA7, 0x00, 0x01]
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let decoded = decodePacket(pack)
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check:
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decoded.isOk()
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check decoded.isOk()
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let packet = decoded.get()
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@ -146,11 +137,12 @@ suite "uTP Packet Encoding":
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packet.header.ackNr == 1
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test "Modify timestamp of encoded packet":
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let synPacket = synPacket(5, 10, 20)
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let initialTimestamp = synPacket.header.timestamp
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let initialAckNr = synPacket.header.ackNr
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let modifiedTimeStamp = initialTimestamp + 120324
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let modifiedAckNr = initialAckNr + 20
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let
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synPacket = synPacket(5, 10, 20)
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initialTimestamp = synPacket.header.timestamp
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initialAckNr = synPacket.header.ackNr
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modifiedTimeStamp = initialTimestamp + 120324
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modifiedAckNr = initialAckNr + 20
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var encoded = encodePacket(synPacket)
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modifyTimeStampAndAckNr(encoded, modifiedTimeStamp, modifiedAckNr)
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