lnd.xprv/lnwire/node_announcement.go

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package lnwire
import (
"bytes"
"fmt"
"image/color"
"io"
"io/ioutil"
"net"
"unicode/utf8"
)
// ErrUnknownAddrType is an error returned if we encounter an unknown address type
// when parsing addresses.
type ErrUnknownAddrType struct {
addrType addressType
}
// Error returns a human readable string describing the error.
//
// NOTE: implements the error interface.
func (e ErrUnknownAddrType) Error() string {
return fmt.Sprintf("unknown address type: %v", e.addrType)
}
// ErrInvalidNodeAlias is an error returned if a node alias we parse on the
// wire is invalid, as in it has non UTF-8 characters.
type ErrInvalidNodeAlias struct{}
// Error returns a human readable string describing the error.
//
// NOTE: implements the error interface.
func (e ErrInvalidNodeAlias) Error() string {
return "node alias has non-utf8 characters"
}
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// NodeAlias is a hex encoded UTF-8 string that may be displayed as an
// alternative to the node's ID. Notice that aliases are not unique and may be
// freely chosen by the node operators.
type NodeAlias [32]byte
// NewNodeAlias creates a new instance of a NodeAlias. Verification is
// performed on the passed string to ensure it meets the alias requirements.
func NewNodeAlias(s string) (NodeAlias, error) {
var n NodeAlias
if len(s) > 32 {
return n, fmt.Errorf("alias too large: max is %v, got %v", 32,
len(s))
}
if !utf8.ValidString(s) {
return n, &ErrInvalidNodeAlias{}
}
copy(n[:], []byte(s))
return n, nil
}
// String returns a utf8 string representation of the alias bytes.
func (n NodeAlias) String() string {
// Trim trailing zero-bytes for presentation
return string(bytes.Trim(n[:], "\x00"))
}
// NodeAnnouncement message is used to announce the presence of a Lightning
// node and also to signal that the node is accepting incoming connections.
// Each NodeAnnouncement authenticating the advertised information within the
// announcement via a signature using the advertised node pubkey.
type NodeAnnouncement struct {
// Signature is used to prove the ownership of node id.
Signature Sig
// Features is the list of protocol features this node supports.
Features *RawFeatureVector
// Timestamp allows ordering in the case of multiple announcements.
Timestamp uint32
// NodeID is a public key which is used as node identification.
NodeID [33]byte
// RGBColor is used to customize their node's appearance in maps and
// graphs
RGBColor color.RGBA
// Alias is used to customize their node's appearance in maps and
// graphs
Alias NodeAlias
// Address includes two specification fields: 'ipv6' and 'port' on
// which the node is accepting incoming connections.
Addresses []net.Addr
// ExtraOpaqueData is the set of data that was appended to this
// message, some of which we may not actually know how to iterate or
// parse. By holding onto this data, we ensure that we're able to
// properly validate the set of signatures that cover these new fields,
// and ensure we're able to make upgrades to the network in a forwards
// compatible manner.
ExtraOpaqueData []byte
}
// A compile time check to ensure NodeAnnouncement implements the
// lnwire.Message interface.
var _ Message = (*NodeAnnouncement)(nil)
// Decode deserializes a serialized NodeAnnouncement stored in the passed
// io.Reader observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
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func (a *NodeAnnouncement) Decode(r io.Reader, pver uint32) error {
err := ReadElements(r,
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&a.Signature,
&a.Features,
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&a.Timestamp,
&a.NodeID,
&a.RGBColor,
&a.Alias,
&a.Addresses,
)
if err != nil {
return err
}
// Now that we've read out all the fields that we explicitly know of,
// we'll collect the remainder into the ExtraOpaqueData field. If there
// aren't any bytes, then we'll snip off the slice to avoid carrying
// around excess capacity.
a.ExtraOpaqueData, err = ioutil.ReadAll(r)
if err != nil {
return err
}
if len(a.ExtraOpaqueData) == 0 {
a.ExtraOpaqueData = nil
}
return nil
}
// Encode serializes the target NodeAnnouncement into the passed io.Writer
// observing the protocol version specified.
//
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func (a *NodeAnnouncement) Encode(w io.Writer, pver uint32) error {
return WriteElements(w,
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a.Signature,
a.Features,
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a.Timestamp,
a.NodeID,
a.RGBColor,
a.Alias,
a.Addresses,
a.ExtraOpaqueData,
)
}
// MsgType returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
func (a *NodeAnnouncement) MsgType() MessageType {
return MsgNodeAnnouncement
}
// MaxPayloadLength returns the maximum allowed payload size for this message
// observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
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func (a *NodeAnnouncement) MaxPayloadLength(pver uint32) uint32 {
return 65533
}
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// DataToSign returns the part of the message that should be signed.
func (a *NodeAnnouncement) DataToSign() ([]byte, error) {
// We should not include the signatures itself.
var w bytes.Buffer
err := WriteElements(&w,
a.Features,
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a.Timestamp,
a.NodeID,
a.RGBColor,
a.Alias[:],
a.Addresses,
a.ExtraOpaqueData,
)
if err != nil {
return nil, err
}
return w.Bytes(), nil
}