# BOLT #1: Base Protocol ## Overview This protocol assumes an underlying authenticated and ordered transport mechanism that takes care of framing individual messages. [BOLT #8](08-transport.md) 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](#reference-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](#connection-handling-and-multiplexing) * [Lightning Message Format](#lightning-message-format) * [Type-Length-Value Format](#type-length-value-format) * [Fundamental Types](#fundamental-types) * [Setup Messages](#setup-messages) * [The `init` Message](#the-init-message) * [The `error` and `warning` Messages](#the-error-and-warning-messages) * [Control Messages](#control-messages) * [The `ping` and `pong` Messages](#the-ping-and-pong-messages) * [Appendix A: BigSize Test Vectors](#appendix-a-bigsize-test-vectors) * [Appendix B: Type-Length-Value Test Vectors](#appendix-b-type-length-value-test-vectors) * [Appendix C: Message Extension](#appendix-c-message-extension) * [Acknowledgments](#acknowledgments) * [References](#references) * [Authors](#authors) ## 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](#type-length-value-format) 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](02-peer-protocol.md)) - 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](02-peer-protocol.md)) - Routing (types `256`-`511`): messages containing node and channel announcements, as well as any active route exploration (described in [BOLT #7](07-routing-gossip.md)) - 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](https://github.com/lightningnetwork/lightning-rfc/issues/716). - 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_record`s, represented as the concatenation of the encoded `tlv_record`s. 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_record`s 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 `type`s 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 `type`s 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 `value`s. - 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 `type`s or short `value`s. This potentially leaves more space for application data over the wire or in an onion payload. All `type`s must appear in increasing order to create a canonical encoding of the underlying `tlv_record`s. 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](00-introduction.md#glossary-and-terminology-guide)) * `channel_id`: a 32-byte channel_id (see [BOLT #2](02-peer-protocol.md#definition-of-channel-id)) * `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](http://www.secg.org/sec1-v2.pdf#subsubsection.2.3.3)) * `short_channel_id`: an 8 byte value identifying a channel (see [BOLT #7](07-routing-gossip.md#definition-of-short-channel-id)) * `bigsize`: a variable-length, unsigned integer similar to Bitcoin's CompactSize encoding, but big-endian. Described in [BigSize](#appendix-a-bigsize-test-vectors). ## 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](09-features.md) 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`] 1. `tlv_stream`: `init_tlvs` 2. types: 1. type: 1 (`networks`) 2. data: * [`...*chain_hash`:`chains`] 1. type: 3 (`remote_addr`) 2. 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](09-features.md). - 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](07-routing-gossip.md#the-node_announcement-message). - 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](09-features.md). - 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`] 1. type: 1 (`warning`) 2. 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](04-onion-routing.md), 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](08-transport.md). ## 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. ```golang 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: ```json [ { "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. ```golang 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: ```json [ { "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 1. Invalid stream: 0xfd01 2. Reason: type truncated 1. Invalid stream: 0xfd0001 00 2. Reason: not minimally encoded type 1. Invalid stream: 0xfd0101 2. Reason: missing length 1. Invalid stream: 0x0f fd 2. Reason: (length truncated) 1. Invalid stream: 0x0f fd26 2. Reason: (length truncated) 1. Invalid stream: 0x0f fd2602 2. Reason: missing value 1. Invalid stream: 0x0f fd0001 00 2. Reason: not minimally encoded length 1. Invalid stream: 0x0f fd0201 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 2. 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. 1. Invalid stream: 0xfd0102 00 2. Reason: unknown even type. 1. Invalid stream: 0xfe01000002 00 2. Reason: unknown even type. 1. Invalid stream: 0xff0100000000000002 00 2. 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 `n1`s `tlv1`. 1. Invalid stream: 0x01 01 00 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x01 02 0001 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x01 03 000100 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x01 04 00010000 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x01 05 0001000000 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x01 06 000100000000 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x01 07 00010000000000 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x01 08 0001000000000000 2. Reason: encoding for `n1`s `tlv1`s `amount_msat` is not minimal 1. Invalid stream: 0x02 07 01010101010101 2. Reason: less than encoding length for `n1`s `tlv2`. 1. Invalid stream: 0x02 09 010101010101010101 2. Reason: greater than encoding length for `n1`s `tlv2`. 1. Invalid stream: 0x03 21 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb 2. Reason: less than encoding length for `n1`s `tlv3`. 1. Invalid stream: 0x03 29 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb0000000000000001 2. Reason: less than encoding length for `n1`s `tlv3`. 1. Invalid stream: 0x03 30 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb000000000000000100000000000001 2. Reason: less than encoding length for `n1`s `tlv3`. 1. Invalid stream: 0x03 31 043da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb00000000000000010000000000000002 2. Reason: `n1`s `node_id` is not a valid point. 1. Invalid stream: 0x03 32 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb0000000000000001000000000000000001 2. Reason: greater than encoding length for `n1`s `tlv3`. 1. Invalid stream: 0xfd00fe 00 2. Reason: less than encoding length for `n1`s `tlv4`. 1. Invalid stream: 0xfd00fe 01 01 2. Reason: less than encoding length for `n1`s `tlv4`. 1. Invalid stream: 0xfd00fe 03 010101 2. Reason: greater than encoding length for `n1`s `tlv4`. 1. Invalid stream: 0x00 00 2. Reason: unknown even field for `n1`s 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 1. Valid stream: 0x21 00 2. Explanation: Unknown odd type. 1. Valid stream: 0xfd0201 00 2. Explanation: Unknown odd type. 1. Valid stream: 0xfd00fd 00 2. Explanation: Unknown odd type. 1. Valid stream: 0xfd00ff 00 2. Explanation: Unknown odd type. 1. Valid stream: 0xfe02000001 00 2. Explanation: Unknown odd type. 1. Valid stream: 0xff0200000000000001 00 2. 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 1. Valid stream: 0x01 01 01 2. Values: `tlv1` `amount_msat`=1 1. Valid stream: 0x01 02 0100 2. Values: `tlv1` `amount_msat`=256 1. Valid stream: 0x01 03 010000 2. Values: `tlv1` `amount_msat`=65536 1. Valid stream: 0x01 04 01000000 2. Values: `tlv1` `amount_msat`=16777216 1. Valid stream: 0x01 05 0100000000 2. Values: `tlv1` `amount_msat`=4294967296 1. Valid stream: 0x01 06 010000000000 2. Values: `tlv1` `amount_msat`=1099511627776 1. Valid stream: 0x01 07 01000000000000 2. Values: `tlv1` `amount_msat`=281474976710656 1. Valid stream: 0x01 08 0100000000000000 2. Values: `tlv1` `amount_msat`=72057594037927936 1. Valid stream: 0x02 08 0000000000000226 2. Values: `tlv2` `scid`=0x0x550 1. Valid stream: 0x03 31 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb00000000000000010000000000000002 2. Values: `tlv3` `node_id`=023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb `amount_msat_1`=1 `amount_msat_2`=2 1. Valid stream: 0xfd00fe 02 0226 2. 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 1. Invalid stream: 0x02 08 0000000000000231 02 08 0000000000000451 2. Reason: duplicate TLV type 1. Invalid stream: 0x1f 00 0f 01 2a 2. Reason: valid (ignored) TLV records but invalid ordering 1. Invalid stream: 0x1f 00 1f 01 2a 2. 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](https://i.creativecommons.org/l/by/4.0/88x31.png "License CC-BY")
This work is licensed under a [Creative Commons Attribution 4.0 International License](http://creativecommons.org/licenses/by/4.0/).