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fbe79811cf
In order to reduce the number of calls to the db we try to process as few channels as we can + try to not do extra work for each of them. - First fetch all the channels. Then, filter all the public ones and sort the potential candidates by remote balance. - Filter out each potential candidate as soon as possible. - Only check the alias if the channel supports scid aliases. - Because we sort the channels by remote balance, we will hit the target amount, if possible, as soon as we can. We do not want to leak information about our remote balances, so we shuffle the hop hints (the forced ones go always first) so the invoice receiver does not know which channels have more balance than others.
99 lines
2.9 KiB
Go
99 lines
2.9 KiB
Go
package lnwire
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import (
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"fmt"
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"io"
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"github.com/lightningnetwork/lnd/tlv"
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)
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const (
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// AliasScidRecordType is the type of the experimental record to denote
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// the alias being used in an option_scid_alias channel.
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AliasScidRecordType tlv.Type = 1
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)
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// ShortChannelID represents the set of data which is needed to retrieve all
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// necessary data to validate the channel existence.
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type ShortChannelID struct {
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// BlockHeight is the height of the block where funding transaction
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// located.
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//
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// NOTE: This field is limited to 3 bytes.
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BlockHeight uint32
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// TxIndex is a position of funding transaction within a block.
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//
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// NOTE: This field is limited to 3 bytes.
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TxIndex uint32
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// TxPosition indicating transaction output which pays to the channel.
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TxPosition uint16
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}
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// NewShortChanIDFromInt returns a new ShortChannelID which is the decoded
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// version of the compact channel ID encoded within the uint64. The format of
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// the compact channel ID is as follows: 3 bytes for the block height, 3 bytes
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// for the transaction index, and 2 bytes for the output index.
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func NewShortChanIDFromInt(chanID uint64) ShortChannelID {
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return ShortChannelID{
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BlockHeight: uint32(chanID >> 40),
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TxIndex: uint32(chanID>>16) & 0xFFFFFF,
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TxPosition: uint16(chanID),
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}
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}
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// ToUint64 converts the ShortChannelID into a compact format encoded within a
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// uint64 (8 bytes).
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func (c ShortChannelID) ToUint64() uint64 {
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// TODO(roasbeef): explicit error on overflow?
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return ((uint64(c.BlockHeight) << 40) | (uint64(c.TxIndex) << 16) |
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(uint64(c.TxPosition)))
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}
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// String generates a human-readable representation of the channel ID.
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func (c ShortChannelID) String() string {
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return fmt.Sprintf("%d:%d:%d", c.BlockHeight, c.TxIndex, c.TxPosition)
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}
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// Record returns a TLV record that can be used to encode/decode a
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// ShortChannelID to/from a TLV stream.
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func (c *ShortChannelID) Record() tlv.Record {
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return tlv.MakeStaticRecord(
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AliasScidRecordType, c, 8, EShortChannelID, DShortChannelID,
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)
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}
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// IsDefault returns true if the ShortChannelID represents the zero value for
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// its type.
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func (c ShortChannelID) IsDefault() bool {
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return c == ShortChannelID{}
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}
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// EShortChannelID is an encoder for ShortChannelID. It is exported so other
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// packages can use the encoding scheme.
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func EShortChannelID(w io.Writer, val interface{}, buf *[8]byte) error {
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if v, ok := val.(*ShortChannelID); ok {
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return tlv.EUint64T(w, v.ToUint64(), buf)
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}
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return tlv.NewTypeForEncodingErr(val, "lnwire.ShortChannelID")
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}
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// DShortChannelID is a decoder for ShortChannelID. It is exported so other
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// packages can use the decoding scheme.
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func DShortChannelID(r io.Reader, val interface{}, buf *[8]byte,
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l uint64) error {
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if v, ok := val.(*ShortChannelID); ok {
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var scid uint64
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err := tlv.DUint64(r, &scid, buf, 8)
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if err != nil {
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return err
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}
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*v = NewShortChanIDFromInt(scid)
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return nil
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}
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return tlv.NewTypeForDecodingErr(val, "lnwire.ShortChannelID", l, 8)
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}
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