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BOLT #1: Base Protocol

Overview

This protocol assumes an underlying authenticated and ordered transport mechanism that takes care of framing individual messages. BOLT #8 specifies the canonical transport layer used in Lightning, though it can be replaced by any transport that fulfills the above guarantees.

The default TCP port depends on the network used. The most common networks are:

  • Bitcoin mainet with port number 9735 or the corresponding hexadecimal 0x2607;
  • Bitcoin testnet with port number 19735 (0x4D17);
  • Bitcoin signet with port number 39735 (0xF87).

The Unicode code point for LIGHTNING 1, and the port convention try to follow the Bitcoin Core convention.

All data fields are unsigned big-endian unless otherwise specified.

Table of Contents

Connection Handling and Multiplexing

Implementations MUST use a single connection per peer; channel messages (which include a channel ID) are multiplexed over this single connection.

Lightning Message Format

After decryption, all Lightning messages are of the form:

  1. type: a 2-byte big-endian field indicating the type of message
  2. payload: a variable-length payload that comprises the remainder of the message and that conforms to a format matching the type
  3. extension: an optional TLV stream

The type field indicates how to interpret the payload field. The format for each individual type is defined by a specification in this repository. The type follows the it's ok to be odd rule, so nodes MAY send odd-numbered types without ascertaining that the recipient understands it.

The messages are grouped logically into five groups, ordered by the most significant bit that is set:

  • Setup & Control (types 0-31): messages related to connection setup, control, supported features, and error reporting (described below)
  • Channel (types 32-127): messages used to setup and tear down micropayment channels (described in BOLT #2)
  • Commitment (types 128-255): messages related to updating the current commitment transaction, which includes adding, revoking, and settling HTLCs as well as updating fees and exchanging signatures (described in BOLT #2)
  • Routing (types 256-511): messages containing node and channel announcements, as well as any active route exploration (described in BOLT #7)
  • Custom (types 32768-65535): experimental and application-specific messages

The size of the message is required by the transport layer to fit into a 2-byte unsigned int; therefore, the maximum possible size is 65535 bytes.

A sending node:

  • MUST NOT send an evenly-typed message not listed here without prior negotiation.
  • MUST NOT send evenly-typed TLV records in the extension without prior negotiation.
  • that negotiates an option in this specification:
    • MUST include all the fields annotated with that option.
  • When defining custom messages:
    • SHOULD pick a random type to avoid collision with other custom types.
    • SHOULD pick a type that doesn't conflict with other experiments listed in this issue.
    • SHOULD pick an odd type identifiers when regular nodes should ignore the additional data.
    • SHOULD pick an even type identifiers when regular nodes should reject the message and close the connection.

A receiving node:

  • upon receiving a message of odd, unknown type:
    • MUST ignore the received message.
  • upon receiving a message of even, unknown type:
    • MUST close the connection.
    • MAY fail the channels.
  • upon receiving a known message with insufficient length for the contents:
    • MUST close the connection.
    • MAY fail the channels.
  • upon receiving a message with an extension:
    • MAY ignore the extension.
    • Otherwise, if the extension is invalid:
      • MUST close the connection.
      • MAY fail the channels.

Rationale

By default SHA2 and Bitcoin public keys are both encoded as big endian, thus it would be unusual to use a different endian for other fields.

Length is limited to 65535 bytes by the cryptographic wrapping, and messages in the protocol are never more than that length anyway.

The it's ok to be odd rule allows for future optional extensions without negotiation or special coding in clients. The extension field similarly allows for future expansion by letting senders include additional TLV data. Note that an extension field can only be added when the message payload doesn't already fill the 65535 bytes maximum length.

Implementations may prefer to have message data aligned on an 8-byte boundary (the largest natural alignment requirement of any type here); however, adding a 6-byte padding after the type field was considered wasteful: alignment may be achieved by decrypting the message into a buffer with 6-bytes of pre-padding.

Type-Length-Value Format

Throughout the protocol, a TLV (Type-Length-Value) format is used to allow for the backwards-compatible addition of new fields to existing message types.

A tlv_record represents a single field, encoded in the form:

  • [bigsize: type]
  • [bigsize: length]
  • [length: value]

A tlv_stream is a series of (possibly zero) tlv_records, represented as the concatenation of the encoded tlv_records. When used to extend existing messages, a tlv_stream is typically placed after all currently defined fields.

The type is encoded using the BigSize format. It functions as a message-specific, 64-bit identifier for the tlv_record determining how the contents of value should be decoded. type identifiers below 2^16 are reserved for use in this specification. type identifiers greater than or equal to 2^16 are available for custom records. Any record not defined in this specification is considered a custom record. This includes experimental and application-specific messages.

The length is encoded using the BigSize format signaling the size of value in bytes.

The value depends entirely on the type, and should be encoded or decoded according to the message-specific format determined by type.

Requirements

The sending node:

  • MUST order tlv_records in a tlv_stream by strictly-increasing type, hence MUST not produce more than a single TLV record with the same type
  • MUST minimally encode type and length.
  • When defining custom record type identifiers:
    • SHOULD pick random type identifiers to avoid collision with other custom types.
    • SHOULD pick odd type identifiers when regular nodes should ignore the additional data.
    • SHOULD pick even type identifiers when regular nodes should reject the full tlv stream containing the custom record.
  • SHOULD NOT use redundant, variable-length encodings in a tlv_record.

The receiving node:

  • if zero bytes remain before parsing a type:
    • MUST stop parsing the tlv_stream.
  • if a type or length is not minimally encoded:
    • MUST fail to parse the tlv_stream.
  • if decoded types are not strictly-increasing (including situations when two or more occurrences of the same type are met):
    • MUST fail to parse the tlv_stream.
  • if length exceeds the number of bytes remaining in the message:
    • MUST fail to parse the tlv_stream.
  • if type is known:
    • MUST decode the next length bytes using the known encoding for type.
    • if length is not exactly equal to that required for the known encoding for type:
      • MUST fail to parse the tlv_stream.
    • if variable-length fields within the known encoding for type are not minimal:
      • MUST fail to parse the tlv_stream.
  • otherwise, if type is unknown:
    • if type is even:
      • MUST fail to parse the tlv_stream.
    • otherwise, if type is odd:
      • MUST discard the next length bytes.

Rationale

The primary advantage in using TLV is that a reader is able to ignore new fields that it does not understand, since each field carries the exact size of the encoded element. Without TLV, even if a node does not wish to use a particular field, the node is forced to add parsing logic for that field in order to determine the offset of any fields that follow.

The strict monotonicity constraint ensures that all types are unique and can appear at most once. Fields that map to complex objects, e.g. vectors, maps, or structs, should do so by defining the encoding such that the object is serialized within a single tlv_record. The uniqueness constraint, among other things, enables the following optimizations:

  • canonical ordering is defined independent of the encoded values.
  • canonical ordering can be known at compile-time, rather than being determined dynamically at the time of encoding.
  • verifying canonical ordering requires less state and is less-expensive.
  • variable-size fields can reserve their expected size up front, rather than appending elements sequentially and incurring double-and-copy overhead.

The use of a bigsize for type and length permits a space savings for small types or short values. This potentially leaves more space for application data over the wire or in an onion payload.

All types must appear in increasing order to create a canonical encoding of the underlying tlv_records. This is crucial when computing signatures over a tlv_stream, as it ensures verifiers will be able to recompute the same message digest as the signer. Note that the canonical ordering over the set of fields can be enforced even if the verifier does not understand what the fields contain.

Writers should avoid using redundant, variable-length encodings in a tlv_record since this results in encoding the length twice and complicates computing the outer length. As an example, when writing a variable length byte array, the value should contain only the raw bytes and forgo an additional internal length since the tlv_record already carries the number of bytes that follow. On the other hand, if a tlv_record contains multiple, variable-length elements then this would not be considered redundant, and is needed to allow the receiver to parse individual elements from value.

Fundamental Types

Various fundamental types are referred to in the message specifications:

  • byte: an 8-bit byte
  • u16: a 2 byte unsigned integer
  • u32: a 4 byte unsigned integer
  • u64: an 8 byte unsigned integer

For the final value in TLV records, truncated integers may be used. Leading zeros in truncated integers MUST be omitted:

  • tu16: a 0 to 2 byte truncated unsigned integer
  • tu32: a 0 to 4 byte truncated unsigned integer
  • tu64: a 0 to 8 byte truncated unsigned integer

When used to encode amounts, the previous fields MUST comply with the upper bound of 21 million BTC:

  • satoshi amounts MUST be at most 0x000775f05a074000
  • milli-satoshi amounts MUST be at most 0x1d24b2dfac520000

The following convenience types are also defined:

  • chain_hash: a 32-byte chain identifier (see BOLT #0)
  • channel_id: a 32-byte channel_id (see BOLT #2)
  • sha256: a 32-byte SHA2-256 hash
  • signature: a 64-byte bitcoin Elliptic Curve signature
  • point: a 33-byte Elliptic Curve point (compressed encoding as per SEC 1 standard)
  • short_channel_id: an 8 byte value identifying a channel (see BOLT #7)
  • bigsize: a variable-length, unsigned integer similar to Bitcoin's CompactSize encoding, but big-endian. Described in BigSize.

Setup Messages

The init Message

Once authentication is complete, the first message reveals the features supported or required by this node, even if this is a reconnection.

BOLT #9 specifies lists of features. Each feature is generally represented by 2 bits. The least-significant bit is numbered 0, which is even, and the next most significant bit is numbered 1, which is odd. For historical reasons, features are divided into global and local feature bitmasks.

The features field MUST be padded to bytes with 0s.

  1. type: 16 (init)

  2. data:

    • [u16:gflen]
    • [gflen*byte:globalfeatures]
    • [u16:flen]
    • [flen*byte:features]
    • [init_tlvs:tlvs]

  3. tlv_stream: init_tlvs

  4. types:

    1. type: 1 (networks)
    2. data:
      • [...*chain_hash:chains]
    3. type: 3 (remote_addr)
    4. data:
      • [...*byte:data]

The optional networks indicates the chains the node is interested in. The optional remote_addr can be used to circumvent NAT issues.

Requirements

The sending node:

  • MUST send init as the first Lightning message for any connection.
  • MUST set feature bits as defined in BOLT #9.
  • MUST set any undefined feature bits to 0.
  • SHOULD NOT set features greater than 13 in globalfeatures.
  • SHOULD use the minimum length required to represent the features field.
  • SHOULD set networks to all chains it will gossip or open channels for.
  • SHOULD set remote_addr to reflect the remote IP address (and port) of an incoming connection, if the node is the receiver and the connection was done via IP.
  • if it sets remote_addr:
    • MUST set it to a valid address descriptor (1 byte type and data) as described in BOLT 7.
    • SHOULD NOT set private addresses as remote_addr.

The receiving node:

  • MUST wait to receive init before sending any other messages.
  • MUST combine (logical OR) the two feature bitmaps into one logical features map.
  • MUST respond to known feature bits as specified in BOLT #9.
  • upon receiving unknown odd feature bits that are non-zero:
    • MUST ignore the bit.
  • upon receiving unknown even feature bits that are non-zero:
    • MUST close the connection.
  • upon receiving networks containing no common chains
    • MAY close the connection.
  • if the feature vector does not set all known, transitive dependencies:
    • MUST close the connection.
  • MAY use the remote_addr to update its node_announcement

Rationale

There used to be two feature bitfields here, but for backwards compatibility they're now combined into one.

This semantic allows both future incompatible changes and future backward compatible changes. Bits should generally be assigned in pairs, in order that optional features may later become compulsory.

Nodes wait for receipt of the other's features to simplify error diagnosis when features are incompatible.

Since all networks share the same port, but most implementations only support a single network, the networks fields avoids nodes erroneously believing they will receive updates about their preferred network, or that they can open channels.

The error and warning Messages

For simplicity of diagnosis, it's often useful to tell a peer that something is incorrect.

  1. type: 17 (error)

  2. data:

    • [channel_id:channel_id]
    • [u16:len]
    • [len*byte:data]

  3. type: 1 (warning)

  4. data:

    • [channel_id:channel_id]
    • [u16:len]
    • [len*byte:data]

Requirements

The channel is referred to by channel_id, unless channel_id is 0 (i.e. all bytes are 0), in which case it refers to all channels.

The funding node:

  • for all error messages sent before (and including) the funding_created message:
    • MUST use temporary_channel_id in lieu of channel_id.

The fundee node:

  • for all error messages sent before (and not including) the funding_signed message:
    • MUST use temporary_channel_id in lieu of channel_id.

A sending node:

  • SHOULD send error for protocol violations or internal errors that make channels unusable or that make further communication unusable.
  • SHOULD send error with the unknown channel_id in reply to messages of type 32-255 related to unknown channels.
  • when sending error:
    • MUST fail the channel(s) referred to by the error message.
    • MAY set channel_id to all zero to indicate all channels.
  • when sending warning:
    • MAY set channel_id to all zero if the warning is not related to a specific channel.
  • MAY send an empty data field.
  • when failure was caused by an invalid signature check:
    • SHOULD include the raw, hex-encoded transaction in reply to a funding_created, funding_signed, closing_signed, or commitment_signed message.

The receiving node:

  • upon receiving error:
    • if channel_id is all zero:
      • MUST fail all channels with the sending node.
    • otherwise:
      • MUST fail the channel referred to by channel_id, if that channel is with the sending node.
  • upon receiving warning:
    • SHOULD log the message for later diagnosis.
    • MAY attempt shutdown if permitted at this point.
  • if no existing channel is referred to by channel_id:
    • MUST ignore the message.
  • if data is not composed solely of printable ASCII characters (For reference: the printable character set includes byte values 32 through 126, inclusive):
    • SHOULD NOT print out data verbatim.

Rationale

There are unrecoverable errors that require an abort of conversations; if the connection is simply dropped, then the peer may retry the connection. It's also useful to describe protocol violations for diagnosis, as this indicates that one peer has a bug.

On the other hand, overuse of error messages has lead to implementations ignoring them (to avoid an otherwise expensive channel break), so the "warning" message was added to allow some degree of retry or recovery for spurious errors.

It may be wise not to distinguish errors in production settings, lest it leak information — hence, the optional data field.

Control Messages

The ping and pong Messages

In order to allow for the existence of long-lived TCP connections, at times it may be required that both ends keep alive the TCP connection at the application level. Such messages also allow obfuscation of traffic patterns.

  1. type: 18 (ping)
  2. data:
    • [u16:num_pong_bytes]
    • [u16:byteslen]
    • [byteslen*byte:ignored]

The pong message is to be sent whenever a ping message is received. It serves as a reply and also serves to keep the connection alive, while explicitly notifying the other end that the receiver is still active. Within the received ping message, the sender will specify the number of bytes to be included within the data payload of the pong message.

  1. type: 19 (pong)
  2. data:
    • [u16:byteslen]
    • [byteslen*byte:ignored]

Requirements

A node sending a ping message:

  • SHOULD set ignored to 0s.
  • MUST NOT set ignored to sensitive data such as secrets or portions of initialized memory.
  • if it doesn't receive a corresponding pong:
    • MAY close the network connection,
      • and MUST NOT fail the channels in this case.

A node sending a pong message:

  • SHOULD set ignored to 0s.
  • MUST NOT set ignored to sensitive data such as secrets or portions of initialized memory.

A node receiving a ping message:

  • if num_pong_bytes is less than 65532:
    • MUST respond by sending a pong message, with byteslen equal to num_pong_bytes.
  • otherwise (num_pong_bytes is not less than 65532):
    • MUST ignore the ping.

A node receiving a pong message:

  • if byteslen does not correspond to any ping's num_pong_bytes value it has sent:
    • MAY close the connection.

Rationale

The largest possible message is 65535 bytes; thus, the maximum sensible byteslen is 65531 — in order to account for the type field (pong) and the byteslen itself. This allows a convenient cutoff for num_pong_bytes to indicate that no reply should be sent.

Connections between nodes within the network may be long lived, as payment channels have an indefinite lifetime. However, it's likely that no new data will be exchanged for a significant portion of a connection's lifetime. Also, on several platforms it's possible that Lightning clients will be put to sleep without prior warning. Hence, a distinct ping message is used, in order to probe for the liveness of the connection on the other side, as well as to keep the established connection active.

Additionally, the ability for a sender to request that the receiver send a response with a particular number of bytes enables nodes on the network to create synthetic traffic. Such traffic can be used to partially defend against packet and timing analysis — as nodes can fake the traffic patterns of typical exchanges without applying any true updates to their respective channels.

When combined with the onion routing protocol defined in BOLT #4, careful statistically driven synthetic traffic can serve to further bolster the privacy of participants within the network.

Limited precautions are recommended against ping flooding, however some latitude is given because of network delays. Note that there are other methods of incoming traffic flooding (e.g. sending odd unknown message types, or padding every message maximally).

Finally, the usage of periodic ping messages serves to promote frequent key rotations as specified within BOLT #8.

Appendix A: BigSize Test Vectors

The following test vectors can be used to assert the correctness of a BigSize implementation used in the TLV format. The format is identical to the CompactSize encoding used in bitcoin, but replaces the little-endian encoding of multi-byte values with big-endian.

Values encoded with BigSize will produce an encoding of either 1, 3, 5, or 9 bytes depending on the size of the integer. The encoding is a piece-wise function that takes a uint64 value x and produces:

        uint8(x)                if x < 0xfd
        0xfd + be16(uint16(x))  if x < 0x10000
        0xfe + be32(uint32(x))  if x < 0x100000000
        0xff + be64(x)          otherwise.

Here + denotes concatenation and be16, be32, and be64 produce a big-endian encoding of the input for 16, 32, and 64-bit integers, respectively.

A value is said to be minimally encoded if it could not be encoded using fewer bytes. For example, a BigSize encoding that occupies 5 bytes but whose value is less than 0x10000 is not minimally encoded. All values decoded with BigSize should be checked to ensure they are minimally encoded.

BigSize Decoding Tests

The following is an example of how to execute the BigSize decoding tests.

func testReadBigSize(t *testing.T, test bigSizeTest) {
        var buf [8]byte 
        r := bytes.NewReader(test.Bytes)
        val, err := tlv.ReadBigSize(r, &buf)
        if err != nil && err.Error() != test.ExpErr {
                t.Fatalf("expected decoding error: %v, got: %v",
                        test.ExpErr, err)
        }

        // If we expected a decoding error, there's no point checking the value.
        if test.ExpErr != "" {
                return
        }

        if val != test.Value {
                t.Fatalf("expected value: %d, got %d", test.Value, val)
        }
}

A correct implementation should pass against these test vectors:

[
    {
        "name": "zero",
        "value": 0,
        "bytes": "00"
    },
    {
        "name": "one byte high",
        "value": 252,
        "bytes": "fc"
    },
    {
        "name": "two byte low",
        "value": 253,
        "bytes": "fd00fd"
    },
    {
        "name": "two byte high",
        "value": 65535,
        "bytes": "fdffff"
    },
    {
        "name": "four byte low",
        "value": 65536,
        "bytes": "fe00010000"
    },
    {
        "name": "four byte high",
        "value": 4294967295,
        "bytes": "feffffffff"
    },
    {
        "name": "eight byte low",
        "value": 4294967296,
        "bytes": "ff0000000100000000"
    },
    {
        "name": "eight byte high",
        "value": 18446744073709551615,
        "bytes": "ffffffffffffffffff"
    },
    {
        "name": "two byte not canonical",
        "value": 0,
        "bytes": "fd00fc",
        "exp_error": "decoded bigsize is not canonical"
    },
    {
        "name": "four byte not canonical",
        "value": 0,
        "bytes": "fe0000ffff",
        "exp_error": "decoded bigsize is not canonical"
    },
    {
        "name": "eight byte not canonical",
        "value": 0,
        "bytes": "ff00000000ffffffff",
        "exp_error": "decoded bigsize is not canonical"
    },
    {
        "name": "two byte short read",
        "value": 0,
        "bytes": "fd00",
        "exp_error": "unexpected EOF"
    },
    {
        "name": "four byte short read",
        "value": 0,
        "bytes": "feffff",
        "exp_error": "unexpected EOF"
    },
    {
        "name": "eight byte short read",
        "value": 0,
        "bytes": "ffffffffff",
        "exp_error": "unexpected EOF"
    },
    {
        "name": "one byte no read",
        "value": 0,
        "bytes": "",
        "exp_error": "EOF"
    },
    {
        "name": "two byte no read",
        "value": 0,
        "bytes": "fd",
        "exp_error": "unexpected EOF"
    },
    {
        "name": "four byte no read",
        "value": 0,
        "bytes": "fe",
        "exp_error": "unexpected EOF"
    },
    {
        "name": "eight byte no read",
        "value": 0,
        "bytes": "ff",
        "exp_error": "unexpected EOF"
    }
]

BigSize Encoding Tests

The following is an example of how to execute the BigSize encoding tests.

func testWriteBigSize(t *testing.T, test bigSizeTest) {
        var (
                w   bytes.Buffer
                buf [8]byte
        )
        err := tlv.WriteBigSize(&w, test.Value, &buf)
        if err != nil {
                t.Fatalf("unable to encode %d as bigsize: %v",
                        test.Value, err)
        }

        if bytes.Compare(w.Bytes(), test.Bytes) != 0 {
                t.Fatalf("expected bytes: %v, got %v",
                        test.Bytes, w.Bytes())
        }
}

A correct implementation should pass against the following test vectors:

[
    {
        "name": "zero",
        "value": 0,
        "bytes": "00"
    },
    {
        "name": "one byte high",
        "value": 252,
        "bytes": "fc"
    },
    {
        "name": "two byte low",
        "value": 253,
        "bytes": "fd00fd"
    },
    {
        "name": "two byte high",
        "value": 65535,
        "bytes": "fdffff"
    },
    {
        "name": "four byte low",
        "value": 65536,
        "bytes": "fe00010000"
    },
    {
        "name": "four byte high",
        "value": 4294967295,
        "bytes": "feffffffff"
    },
    {
        "name": "eight byte low",
        "value": 4294967296,
        "bytes": "ff0000000100000000"
    },
    {
        "name": "eight byte high",
        "value": 18446744073709551615,
        "bytes": "ffffffffffffffffff"
    }
]

Appendix B: Type-Length-Value Test Vectors

The following tests assume that two separate TLV namespaces exist: n1 and n2.

The n1 namespace supports the following TLV types:

  1. tlv_stream: n1
  2. types:
    1. type: 1 (tlv1)
    2. data:
    • [tu64:amount_msat]
    1. type: 2 (tlv2)
    2. data:
    • [short_channel_id:scid]
    1. type: 3 (tlv3)
    2. data:
    • [point:node_id]
    • [u64:amount_msat_1]
    • [u64:amount_msat_2]
    1. type: 254 (tlv4)
    2. data:
    • [u16:cltv_delta]

The n2 namespace supports the following TLV types:

  1. tlv_stream: n2
  2. types:
    1. type: 0 (tlv1)
    2. data:
    • [tu64:amount_msat]
    1. type: 11 (tlv2)
    2. data:
    • [tu32:cltv_expiry]

TLV Decoding Failures

The following TLV streams in any namespace should trigger a decoding failure:

  1. Invalid stream: 0xfd

  2. Reason: type truncated

  3. Invalid stream: 0xfd01

  4. Reason: type truncated

  5. Invalid stream: 0xfd0001 00

  6. Reason: not minimally encoded type

  7. Invalid stream: 0xfd0101

  8. Reason: missing length

  9. Invalid stream: 0x0f fd

  10. Reason: (length truncated)

  11. Invalid stream: 0x0f fd26

  12. Reason: (length truncated)

  13. Invalid stream: 0x0f fd2602

  14. Reason: missing value

  15. Invalid stream: 0x0f fd0001 00

  16. Reason: not minimally encoded length

  17. Invalid stream: 0x0f fd0201 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

  18. Reason: value truncated

The following TLV streams in either namespace should trigger a decoding failure:

  1. Invalid stream: 0x12 00

  2. Reason: unknown even type.

  3. Invalid stream: 0xfd0102 00

  4. Reason: unknown even type.

  5. Invalid stream: 0xfe01000002 00

  6. Reason: unknown even type.

  7. Invalid stream: 0xff0100000000000002 00

  8. Reason: unknown even type.

The following TLV streams in namespace n1 should trigger a decoding failure:

  1. Invalid stream: 0x01 09 ffffffffffffffffff

  2. Reason: greater than encoding length for n1s tlv1.

  3. Invalid stream: 0x01 01 00

  4. Reason: encoding for n1s tlv1s amount_msat is not minimal

  5. Invalid stream: 0x01 02 0001

  6. Reason: encoding for n1s tlv1s amount_msat is not minimal

  7. Invalid stream: 0x01 03 000100

  8. Reason: encoding for n1s tlv1s amount_msat is not minimal

  9. Invalid stream: 0x01 04 00010000

  10. Reason: encoding for n1s tlv1s amount_msat is not minimal

  11. Invalid stream: 0x01 05 0001000000

  12. Reason: encoding for n1s tlv1s amount_msat is not minimal

  13. Invalid stream: 0x01 06 000100000000

  14. Reason: encoding for n1s tlv1s amount_msat is not minimal

  15. Invalid stream: 0x01 07 00010000000000

  16. Reason: encoding for n1s tlv1s amount_msat is not minimal

  17. Invalid stream: 0x01 08 0001000000000000

  18. Reason: encoding for n1s tlv1s amount_msat is not minimal

  19. Invalid stream: 0x02 07 01010101010101

  20. Reason: less than encoding length for n1s tlv2.

  21. Invalid stream: 0x02 09 010101010101010101

  22. Reason: greater than encoding length for n1s tlv2.

  23. Invalid stream: 0x03 21 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb

  24. Reason: less than encoding length for n1s tlv3.

  25. Invalid stream: 0x03 29 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb0000000000000001

  26. Reason: less than encoding length for n1s tlv3.

  27. Invalid stream: 0x03 30 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb000000000000000100000000000001

  28. Reason: less than encoding length for n1s tlv3.

  29. Invalid stream: 0x03 31 043da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb00000000000000010000000000000002

  30. Reason: n1s node_id is not a valid point.

  31. Invalid stream: 0x03 32 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb0000000000000001000000000000000001

  32. Reason: greater than encoding length for n1s tlv3.

  33. Invalid stream: 0xfd00fe 00

  34. Reason: less than encoding length for n1s tlv4.

  35. Invalid stream: 0xfd00fe 01 01

  36. Reason: less than encoding length for n1s tlv4.

  37. Invalid stream: 0xfd00fe 03 010101

  38. Reason: greater than encoding length for n1s tlv4.

  39. Invalid stream: 0x00 00

  40. Reason: unknown even field for n1s namespace.

TLV Decoding Successes

The following TLV streams in either namespace should correctly decode, and be ignored:

  1. Valid stream: 0x

  2. Explanation: empty message

  3. Valid stream: 0x21 00

  4. Explanation: Unknown odd type.

  5. Valid stream: 0xfd0201 00

  6. Explanation: Unknown odd type.

  7. Valid stream: 0xfd00fd 00

  8. Explanation: Unknown odd type.

  9. Valid stream: 0xfd00ff 00

  10. Explanation: Unknown odd type.

  11. Valid stream: 0xfe02000001 00

  12. Explanation: Unknown odd type.

  13. Valid stream: 0xff0200000000000001 00

  14. Explanation: Unknown odd type.

The following TLV streams in n1 namespace should correctly decode, with the values given here:

  1. Valid stream: 0x01 00

  2. Values: tlv1 amount_msat=0

  3. Valid stream: 0x01 01 01

  4. Values: tlv1 amount_msat=1

  5. Valid stream: 0x01 02 0100

  6. Values: tlv1 amount_msat=256

  7. Valid stream: 0x01 03 010000

  8. Values: tlv1 amount_msat=65536

  9. Valid stream: 0x01 04 01000000

  10. Values: tlv1 amount_msat=16777216

  11. Valid stream: 0x01 05 0100000000

  12. Values: tlv1 amount_msat=4294967296

  13. Valid stream: 0x01 06 010000000000

  14. Values: tlv1 amount_msat=1099511627776

  15. Valid stream: 0x01 07 01000000000000

  16. Values: tlv1 amount_msat=281474976710656

  17. Valid stream: 0x01 08 0100000000000000

  18. Values: tlv1 amount_msat=72057594037927936

  19. Valid stream: 0x02 08 0000000000000226

  20. Values: tlv2 scid=0x0x550

  21. Valid stream: 0x03 31 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb00000000000000010000000000000002

  22. Values: tlv3 node_id=023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb amount_msat_1=1 amount_msat_2=2

  23. Valid stream: 0xfd00fe 02 0226

  24. Values: tlv4 cltv_delta=550

TLV Stream Decoding Failure

Any appending of an invalid stream to a valid stream should trigger a decoding failure.

Any appending of a higher-numbered valid stream to a lower-numbered valid stream should not trigger a decoding failure.

In addition, the following TLV streams in namespace n1 should trigger a decoding failure:

  1. Invalid stream: 0x02 08 0000000000000226 01 01 2a

  2. Reason: valid TLV records but invalid ordering

  3. Invalid stream: 0x02 08 0000000000000231 02 08 0000000000000451

  4. Reason: duplicate TLV type

  5. Invalid stream: 0x1f 00 0f 01 2a

  6. Reason: valid (ignored) TLV records but invalid ordering

  7. Invalid stream: 0x1f 00 1f 01 2a

  8. Reason: duplicate TLV type (ignored)

The following TLV stream in namespace n2 should trigger a decoding failure:

  1. Invalid stream: 0xffffffffffffffffff 00 00 00
  2. Reason: valid TLV records but invalid ordering

Appendix C: Message Extension

This section contains examples of valid and invalid extensions on the init message. The base init message (without extensions) for these examples is 0x001000000000 (all features turned off).

The following init messages are valid:

  • 0x001000000000: no extension provided
  • 0x001000000000c9012acb0104: the extension contains two unknown odd TLV records (with types 0xc9 and 0xcb)

The following init messages are invalid:

  • 0x00100000000001: the extension is present but truncated
  • 0x001000000000ca012a: the extension contains unknown even TLV records (assuming that TLV type 0xca is unknown)
  • 0x001000000000c90101c90102: the extension TLV stream is invalid (duplicate TLV record type 0xc9)

Note that when messages are signed, the extension is part of the signed bytes. Nodes should store the extension bytes even if they don't understand them to be able to correctly verify signatures.

Acknowledgments

[ TODO: (roasbeef); fin ]

References

  1. http://www.unicode.org/charts/PDF/U2600.pdf

Authors

[ FIXME: Insert Author List ]

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.