mirror of
https://github.com/lightning/bolts.git
synced 2025-01-18 13:22:35 +01:00
Amend: Make pull request changes; re-structure requirements; correct grammar
Implement changes requested by @rustyrussell: wording change, structure requirements according to whether nodes are sending or receiving; Correct grammar, punctuation, capitalization, and style for correctness, concision, clarity, comprehension, and consistency;
This commit is contained in:
Landon Mutch
parent
2f6a629a03
commit
2d829756e1
161
01-messaging.md
161
01-messaging.md
@ -4,7 +4,7 @@
|
||||
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 is 9735. This corresponds to hexadecimal `0x2607`, the Unicode code point for LIGHTNING.<sup>[1](#reference-1)</sup>
|
||||
The default TCP port is 9735. This corresponds to hexadecimal `0x2607`: the Unicode code point for LIGHTNING.<sup>[1](#reference-1)</sup>
|
||||
|
||||
All data fields are big-endian unless otherwise specified.
|
||||
|
||||
@ -22,12 +22,12 @@ All data fields are big-endian unless otherwise specified.
|
||||
|
||||
## Connection Handling and Multiplexing
|
||||
|
||||
Implementations MUST use one connection per peer, channel messages (which include a channel id) are multiplexed over this single connection.
|
||||
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:
|
||||
After decryption, all Lightning messages are of the form:
|
||||
|
||||
1. `type`: 2 byte big-endian field indicating the type of message.
|
||||
2. `payload`: variable length payload which comprises the remainder of
|
||||
@ -35,15 +35,16 @@ After decryption, all lightning messages are of the form:
|
||||
|
||||
The `type` field indicates how to interpret the `payload` field.
|
||||
The format for each individual type is specified in 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 type follows the _it's ok to be odd_ rule, so nodes MAY send <i>odd</i>-numbered types without ascertaining that the recipient understands it.
|
||||
|
||||
A node:
|
||||
- MUST NOT send an evenly-typed message not listed here without prior negotiation.
|
||||
- when receives message of unknown type
|
||||
- if that type is odd
|
||||
- MUST ignore the received message.
|
||||
- otherwise type is even
|
||||
- MUST fail the channels.
|
||||
A sending node:
|
||||
- MUST NOT send an evenly-typed message not listed here, without prior negotiation.
|
||||
|
||||
A receiving node:
|
||||
- upon receiving a message of <i>odd</i>, unknown type:
|
||||
- MUST ignore the received message.
|
||||
- upon receiving a message of <i>even</i>, unknown type:
|
||||
- MUST fail the channels.
|
||||
|
||||
The messages are grouped logically into 4 groups, ordered by their most significant set bit:
|
||||
|
||||
@ -52,11 +53,11 @@ The messages are grouped logically into 4 groups, ordered by their most signific
|
||||
- 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. These are described in [BOLT #2](02-peer-protocol.md).
|
||||
- Routing (types `256`-`511`): node and channel announcements, as well as any active route exploration. These are described in [BOLT #7](07-routing-gossip.md).
|
||||
|
||||
The size of the message is required to fit into a 2 byte unsigned int by the transport layer, therefore the maximum possible size is 65535 bytes.
|
||||
The size of the message is required to fit into a 2 byte unsigned int by the transport layer; therefore, the maximum possible size is 65535 bytes.
|
||||
|
||||
A node:
|
||||
A receiving node:
|
||||
- MUST ignore any additional data within a message, beyond the length it expects for that type.
|
||||
- if it receives a known message with insufficient length for the contents
|
||||
- upon receiving a known message with insufficient length for the contents:
|
||||
- MUST fail the channels.
|
||||
|
||||
### Rationale
|
||||
@ -69,12 +70,12 @@ 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 "ignore
|
||||
without negotiation or special coding in clients. The "ignore
|
||||
additional data" rule similarly allows for future expansion.
|
||||
|
||||
Implementations may prefer to have message data aligned on an 8 byte
|
||||
boundary (the largest natural alignment requirement of any type here),
|
||||
but adding a 6 byte padding after the type field was considered
|
||||
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.
|
||||
|
||||
@ -83,7 +84,7 @@ a buffer with 6 bytes of pre-padding.
|
||||
### 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 global and local features. Each feature is generally represented in `globalfeatures` or `localfeatures` 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.
|
||||
[BOLT #9](09-features.md) specifies lists of global and local features. Each feature is generally represented in `globalfeatures` or `localfeatures` by 2 bits. The least-significant bit is numbered 0, which is <i>even</i>, and the next most significant bit is numbered 1, which is <i>odd</i>.
|
||||
|
||||
Both fields `globalfeatures` and `localfeatures` MUST be padded to bytes with zeros.
|
||||
|
||||
@ -98,40 +99,35 @@ The 2 byte `gflen` and `lflen` fields indicate the number of bytes in the immedi
|
||||
|
||||
#### Requirements
|
||||
|
||||
Each node:
|
||||
- MUST send `init` as the first lightning message for any connection.
|
||||
- MUST wait to receive `init` before sending any other messages.
|
||||
|
||||
The sending node:
|
||||
- SHOULD use the minimum lengths required to represent the feature fields.
|
||||
- MUST set feature bits as defined in [BOLT #9](09-features.md)
|
||||
- MUST send `init` as the first Lightning message for any connection.
|
||||
- SHOULD use the minimum lengths required to represent the feature fields.
|
||||
- MUST set feature bits as defined in [BOLT #9](09-features.md).
|
||||
- MUST set to zero any feature bits that are not defined.
|
||||
|
||||
The receiving node:
|
||||
- MUST wait to receive `init` before sending any other messages.
|
||||
- MUST respond to known feature bits as specified in [BOLT #9](09-features.md).
|
||||
- for unknown feature bits which are non-zero:
|
||||
- if the bit number is odd
|
||||
- MUST ignore the bit.
|
||||
- otherwise the bit number is even
|
||||
- MUST fail the connection.
|
||||
- upon receiving <i>odd</i> feature bits which are non-zero:
|
||||
- MUST ignore the bit.
|
||||
- upon receiving <i>even</i> feature bits which are non-zero:
|
||||
- MUST fail the connection.
|
||||
|
||||
|
||||
#### Rationale
|
||||
|
||||
This semantic allows future incompatible changes and/or backward
|
||||
compatible changes. Bits should generally be assigned in pairs, so
|
||||
that optional features can later become compulsory.
|
||||
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, where features are incompatible.
|
||||
|
||||
The feature masks are split into local features, which only affect the
|
||||
protocol between these two nodes, and global features, which can affect
|
||||
HTLCs and thus are also advertised to other nodes.
|
||||
The feature masks are split into local features (which only affect the
|
||||
protocol between these two nodes) and global features (which can affect
|
||||
HTLCs) and are thus also advertised to other nodes.
|
||||
|
||||
### The `error` Message
|
||||
|
||||
For simplicity of diagnosis, it is often useful to tell the peer that something is incorrect.
|
||||
For simplicity of diagnosis, it's often useful to tell a peer that something is incorrect.
|
||||
|
||||
1. type: 17 (`error`)
|
||||
2. data:
|
||||
@ -143,42 +139,47 @@ The 2-byte `len` field indicates the number of bytes in the immediately followin
|
||||
|
||||
#### Requirements
|
||||
|
||||
The channel is referred to by `channel_id`, unless `channel_id` is zero (ie. all bytes are zero), in which case it refers to all channels.
|
||||
The channel is referred to by `channel_id`, unless `channel_id` is zero (i.e. all bytes are zero), in which case it refers to all channels.
|
||||
|
||||
The funding node:
|
||||
- for all error messages sent before (and including) the `funding_created` message
|
||||
- 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
|
||||
- for all error messages sent before (and not including) the `funding_signed` message:
|
||||
- MUST use `temporary_channel_id` in lieu of `channel_id`.
|
||||
|
||||
A node:
|
||||
A sending node:
|
||||
- when sending `error`:
|
||||
- MUST fail the channel referred to by the error message.
|
||||
- SHOULD send `error` for protocol violations or internal errors which make channels unusable or further communication unusable.
|
||||
- MAY send an empty `data` field.
|
||||
- SHOULD include the raw, hex-encoded transaction in reply to a `funding_created`, `funding_signed`, `closing_signed`, or `commitment_signed` message when failure was caused by an invalid signature check.
|
||||
- when sending or receiving `error`
|
||||
- MUST fail the channel referred to by the error message
|
||||
- when `channel_id` is zero
|
||||
- MUST fail all channels
|
||||
- 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.
|
||||
- when `channel_id` is zero:
|
||||
- MUST fail all channels,
|
||||
- and MUST close the connection.
|
||||
- MUST set `len` equal to the length of `data`.
|
||||
- MUST set `len` equal to the length of `data`.
|
||||
|
||||
The receiving node:
|
||||
- if no existing channel is referred to by the message
|
||||
- upon receiving `error`:
|
||||
- MUST fail the channel referred to by the error message.
|
||||
- if no existing channel is referred to by the message:
|
||||
- MUST ignore the message.
|
||||
- MUST truncate `len` to the remainder of the packet if it is larger.
|
||||
- SHOULD only print out `data` verbatim if the string is composed solely of printable ASCII characters (For reference: the printable character set includes byte values 32 through 127, inclusive).
|
||||
- if it's larger:
|
||||
- MUST truncate `len` to the remainder of the packet.
|
||||
- if the string is composed solely of printable ASCII characters (For reference: the printable character set includes byte values 32 through 127, inclusive):
|
||||
- SHOULD only print out `data` verbatim.
|
||||
|
||||
#### Rationale
|
||||
|
||||
There are unrecoverable errors which require an abort of conversations;
|
||||
if the connection is simply dropped then the peer may retry the
|
||||
if the connection is simply dropped, then the peer may retry the
|
||||
connection. It's also useful to describe protocol violations for
|
||||
diagnosis, as it indicates that one peer has a bug.
|
||||
diagnosis, as this indicates that one peer has a bug.
|
||||
|
||||
It may be wise not to distinguish errors in production settings, lest
|
||||
it leak information, thus the optional `data` field.
|
||||
it leak information — hence, the optional `data` field.
|
||||
|
||||
## Control Messages
|
||||
|
||||
@ -195,7 +196,7 @@ application level. Such messages also allow obfuscation of traffic patterns.
|
||||
* [`byteslen`:`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
|
||||
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.
|
||||
@ -207,46 +208,50 @@ included within the data payload of the `pong` message.
|
||||
|
||||
#### Requirements
|
||||
|
||||
A node:
|
||||
- when sending `pong` or `ping`:
|
||||
- SHOULD set `ignored` to zeroes
|
||||
- but MUST NOT set `ignored` to sensitive data such as secrets or portions of initialized
|
||||
A node sending a `ping` message:
|
||||
- SHOULD set `ignored` to zeros,
|
||||
- but MUST NOT set `ignored` to sensitive data such as secrets or portions of initialized
|
||||
memory.
|
||||
- SHOULD NOT send `ping` messages more often than once every 30 seconds
|
||||
- MAY terminate the network connection if it does not receive a corresponding
|
||||
`pong`
|
||||
- if it doesn't receive a corresponding `pong`:
|
||||
- MAY terminate the network connection,
|
||||
- and MUST NOT fail the channels in this case.
|
||||
- SHOULD NOT send `ping` messages more often than once every 30 seconds.
|
||||
|
||||
A node sending a `pong` message:
|
||||
- SHOULD set `ignored` to zeros,
|
||||
- but MUST NOT set `ignored` to sensitive data such as secrets or portions of initialized
|
||||
memory.
|
||||
|
||||
A node receiving a `ping` message:
|
||||
- SHOULD fail the channels if it has received significantly in excess of one `ping` per 30 seconds
|
||||
- if `num_pong_bytes` is less than 65532
|
||||
- MUST respond by sending a `pong` message, with `byteslen` equal to `num_pong_bytes`
|
||||
- otherwise
|
||||
- SHOULD fail the channels if it has received significantly in excess of one `ping` per 30 seconds.
|
||||
- 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 <b>not</b> less than 65532):
|
||||
- it MUST ignore the `ping`.
|
||||
|
||||
A node receiving a `pong` message:
|
||||
- MAY fail the channels, if `byteslen` does not
|
||||
correspond to any `ping` `num_pong_bytes` value it has sent.
|
||||
- if `byteslen` does not correspond to any `ping`'s `num_pong_bytes` value it has sent:
|
||||
- MAY fail the channels.
|
||||
|
||||
### 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
|
||||
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 very long lived, as payment
|
||||
channels have an indefinite lifetime. However, it's likely that for a
|
||||
significant portion of the life-time of a connection, no new data will be
|
||||
exchanged. Additionally, on several platforms it's possible that Lightning
|
||||
clients will be put to sleep without prior warning. As a result, we use a
|
||||
distinct ping message in order to probe for the liveness of the connection on
|
||||
the other side as well as to keep the established connection active.
|
||||
significant portion of the lifetime of a connection, no new data will be
|
||||
exchanged. Also, on several platforms it's possible that Lightning
|
||||
clients will be put to sleep without prior warning. Hence, we use a
|
||||
distinct `ping` message, 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
|
||||
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
|
||||
@ -256,7 +261,7 @@ 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 (eg. sending odd unknown message types, or padding
|
||||
of incoming traffic flooding (e.g. sending <i>odd</i> unknown message types, or padding
|
||||
every message maximally).
|
||||
|
||||
Finally, the usage of periodic `ping` messages serves to promote frequent key
|
||||
@ -265,7 +270,7 @@ rotations as specified within [BOLT #8](https://github.com/lightningnetwork/ligh
|
||||
|
||||
## Acknowledgments
|
||||
|
||||
TODO(roasbeef); fin
|
||||
[ TODO: (roasbeef); fin ]
|
||||
|
||||
|
||||
## References
|
||||
@ -273,7 +278,7 @@ TODO(roasbeef); fin
|
||||
|
||||
## Authors
|
||||
|
||||
FIXME
|
||||
[ FIXME: Insert Author List ]
|
||||
|
||||
|
||||
<br>
|
||||
|
||||
Loading…
Reference in New Issue
Block a user