lnd.xprv/watchtower/wtdb/tower.go
Wilmer Paulino 1d73a6564f
watchtower: extend client databse with CRUD operations for towers
These operations are currently unused, but will be integrated into the
TowerClient at a later point as future preparation for the
WatchtowerClient RPC subserver, which will allow users to add, remove,
and list the watchtowers currntly in use.
2019-07-30 15:13:23 -07:00

112 lines
3.3 KiB
Go

package wtdb
import (
"io"
"net"
"github.com/btcsuite/btcd/btcec"
"github.com/lightningnetwork/lnd/lnwire"
)
// TowerID is a unique 64-bit identifier allocated to each unique watchtower.
// This allows the client to conserve on-disk space by not needing to always
// reference towers by their pubkey.
type TowerID uint64
// TowerIDFromBytes constructs a TowerID from the provided byte slice. The
// argument must have at least 8 bytes, and should contain the TowerID in
// big-endian byte order.
func TowerIDFromBytes(towerIDBytes []byte) TowerID {
return TowerID(byteOrder.Uint64(towerIDBytes))
}
// Bytes encodes a TowerID into an 8-byte slice in big-endian byte order.
func (id TowerID) Bytes() []byte {
var buf [8]byte
byteOrder.PutUint64(buf[:], uint64(id))
return buf[:]
}
// Tower holds the necessary components required to connect to a remote tower.
// Communication is handled by brontide, and requires both a public key and an
// address.
type Tower struct {
// ID is a unique ID for this record assigned by the database.
ID TowerID
// IdentityKey is the public key of the remote node, used to
// authenticate the brontide transport.
IdentityKey *btcec.PublicKey
// Addresses is a list of possible addresses to reach the tower.
Addresses []net.Addr
}
// AddAddress adds the given address to the tower's in-memory list of addresses.
// If the address's string is already present, the Tower will be left
// unmodified. Otherwise, the adddress is prepended to the beginning of the
// Tower's addresses, on the assumption that it is fresher than the others.
//
// NOTE: This method is NOT safe for concurrent use.
func (t *Tower) AddAddress(addr net.Addr) {
// Ensure we don't add a duplicate address.
addrStr := addr.String()
for _, existingAddr := range t.Addresses {
if existingAddr.String() == addrStr {
return
}
}
// Add this address to the front of the list, on the assumption that it
// is a fresher address and will be tried first.
t.Addresses = append([]net.Addr{addr}, t.Addresses...)
}
// RemoveAddress removes the given address from the tower's in-memory list of
// addresses. If the address doesn't exist, then this will act as a NOP.
func (t *Tower) RemoveAddress(addr net.Addr) {
addrStr := addr.String()
for i, address := range t.Addresses {
if address.String() != addrStr {
continue
}
t.Addresses = append(t.Addresses[:i], t.Addresses[i+1:]...)
return
}
}
// LNAddrs generates a list of lnwire.NetAddress from a Tower instance's
// addresses. This can be used to have a client try multiple addresses for the
// same Tower.
//
// NOTE: This method is NOT safe for concurrent use.
func (t *Tower) LNAddrs() []*lnwire.NetAddress {
addrs := make([]*lnwire.NetAddress, 0, len(t.Addresses))
for _, addr := range t.Addresses {
addrs = append(addrs, &lnwire.NetAddress{
IdentityKey: t.IdentityKey,
Address: addr,
})
}
return addrs
}
// Encode writes the Tower to the passed io.Writer. The TowerID is not
// serialized, since it acts as the key.
func (t *Tower) Encode(w io.Writer) error {
return WriteElements(w,
t.IdentityKey,
t.Addresses,
)
}
// Decode reads a Tower from the passed io.Reader. The TowerID is meant to be
// decoded from the key.
func (t *Tower) Decode(r io.Reader) error {
return ReadElements(r,
&t.IdentityKey,
&t.Addresses,
)
}