channeldb: add new AddrsForNode method

In this commit, we add a new AddrsForNode method. This method will allow
a wrapper sturct to implement the new chanbackup.LiveChannelSource
method which is required to implement the full SCB feature set.

channeldb/db.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"fmt"
+	"net"
 	"os"
 	"path/filepath"
 	"sync"
@@ -772,6 +773,59 @@ func (d *DB) PruneLinkNodes() error {
 	})
 }
 
+// AddrsForNode consults the graph and channel database for all addresses known
+// to the passed node public key.
+func (d *DB) AddrsForNode(nodePub *btcec.PublicKey) ([]net.Addr, error) {
+	var (
+		linkNode  *LinkNode
+		graphNode LightningNode
+	)
+
+	dbErr := d.View(func(tx *bbolt.Tx) error {
+		var err error
+
+		linkNode, err = fetchLinkNode(tx, nodePub)
+		if err != nil {
+			return err
+		}
+
+		// We'll also query the graph for this peer to see if they have
+		// any addresses that we don't currently have stored within the
+		// link node database.
+		nodes := tx.Bucket(nodeBucket)
+		if nodes == nil {
+			return ErrGraphNotFound
+		}
+		compressedPubKey := nodePub.SerializeCompressed()
+		graphNode, err = fetchLightningNode(nodes, compressedPubKey)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+	if dbErr != nil {
+		return nil, dbErr
+	}
+
+	// Now that we have both sources of addrs for this node, we'll use a
+	// map to de-duplicate any addresses between the two sources, and
+	// produce a final list of the combined addrs.
+	addrs := make(map[string]net.Addr)
+	for _, addr := range linkNode.Addresses {
+		addrs[addr.String()] = addr
+	}
+	for _, addr := range graphNode.Addresses {
+		addrs[addr.String()] = addr
+	}
+	dedupedAddrs := make([]net.Addr, 0, len(addrs))
+	for _, addr := range addrs {
+		dedupedAddrs = append(dedupedAddrs, addr)
+	}
+
+	return dedupedAddrs, nil
+}
+
 // syncVersions function is used for safe db version synchronization. It
 // applies migration functions to the current database and recovers the
 // previous state of db if at least one error/panic appeared during migration.

channeldb/db_test.go

@@ -2,10 +2,12 @@ package channeldb
 
 import (
 	"io/ioutil"
+	"net"
 	"os"
 	"path/filepath"
 	"testing"
 
+	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/lnwire"
 )
@@ -147,3 +149,64 @@ func TestFetchClosedChannelForID(t *testing.T) {
 		t.Fatalf("expected ErrClosedChannelNotFound, instead got: %v", err)
 	}
 }
+
+// TestAddrsForNode tests the we're able to properly obtain all the addresses
+// for a target node.
+func TestAddrsForNode(t *testing.T) {
+	t.Parallel()
+
+	cdb, cleanUp, err := makeTestDB()
+	if err != nil {
+		t.Fatalf("unable to make test database: %v", err)
+	}
+	defer cleanUp()
+
+	graph := cdb.ChannelGraph()
+
+	// We'll make a test vertex to insert into the database, as the source
+	// node, but this node will only have half the number of addresses it
+	// usually does.
+	testNode, err := createTestVertex(cdb)
+	if err != nil {
+		t.Fatalf("unable to create test node: %v", err)
+	}
+	testNode.Addresses = []net.Addr{testAddr}
+	if err := graph.SetSourceNode(testNode); err != nil {
+		t.Fatalf("unable to set source node: %v", err)
+	}
+
+	// Next, we'll make a link node with the same pubkey, but with an
+	// additional address.
+	nodePub, err := testNode.PubKey()
+	if err != nil {
+		t.Fatalf("unable to recv node pub: %v", err)
+	}
+	linkNode := cdb.NewLinkNode(
+		wire.MainNet, nodePub, anotherAddr,
+	)
+	if err := linkNode.Sync(); err != nil {
+		t.Fatalf("unable to sync link node: %v", err)
+	}
+
+	// Now that we've created a link node, as well as a vertex for the
+	// node, we'll query for all its addresses.
+	nodeAddrs, err := cdb.AddrsForNode(nodePub)
+	if err != nil {
+		t.Fatalf("unable to obtain node addrs: %v", err)
+	}
+
+	expectedAddrs := make(map[string]struct{})
+	expectedAddrs[testAddr.String()] = struct{}{}
+	expectedAddrs[anotherAddr.String()] = struct{}{}
+
+	// Finally, ensure that all the expected addresses are found.
+	if len(nodeAddrs) != len(expectedAddrs) {
+		t.Fatalf("expected %v addrs, got %v",
+			len(expectedAddrs), len(nodeAddrs))
+	}
+	for _, addr := range nodeAddrs {
+		if _, ok := expectedAddrs[addr.String()]; !ok {
+			t.Fatalf("unexpected addr: %v", addr)
+		}
+	}
+}

channeldb/nodes.go

@@ -62,13 +62,13 @@ type LinkNode struct {
 // NewLinkNode creates a new LinkNode from the provided parameters, which is
 // backed by an instance of channeldb.
 func (db *DB) NewLinkNode(bitNet wire.BitcoinNet, pub *btcec.PublicKey,
-	addr net.Addr) *LinkNode {
+	addrs ...net.Addr) *LinkNode {
 
 	return &LinkNode{
 		Network:     bitNet,
 		IdentityPub: pub,
 		LastSeen:    time.Now(),
-		Addresses:   []net.Addr{addr},
+		Addresses:   addrs,
 		db:          db,
 	}
 }
@@ -149,40 +149,44 @@ func (db *DB) deleteLinkNode(tx *bbolt.Tx, identity *btcec.PublicKey) error {
 // identity public key. If a particular LinkNode for the passed identity public
 // key cannot be found, then ErrNodeNotFound if returned.
 func (db *DB) FetchLinkNode(identity *btcec.PublicKey) (*LinkNode, error) {
-	var (
+	var linkNode *LinkNode
-		node *LinkNode
+	err := db.View(func(tx *bbolt.Tx) error {
-		err  error
+		node, err := fetchLinkNode(tx, identity)
-	)
+		if err != nil {
+			return err
+		}
 
-	err = db.View(func(tx *bbolt.Tx) error {
+		linkNode = node
-		// First fetch the bucket for storing node metadata, bailing
+		return nil
-		// out early if it hasn't been created yet.
+	})
+
+	return linkNode, err
+}
+
+func fetchLinkNode(tx *bbolt.Tx, targetPub *btcec.PublicKey) (*LinkNode, error) {
+	// First fetch the bucket for storing node metadata, bailing out early
+	// if it hasn't been created yet.
 	nodeMetaBucket := tx.Bucket(nodeInfoBucket)
 	if nodeMetaBucket == nil {
-			return ErrLinkNodesNotFound
+		return nil, ErrLinkNodesNotFound
 	}
 
-		// If a link node for that particular public key cannot be
+	// If a link node for that particular public key cannot be located,
-		// located, then exit early with an ErrNodeNotFound.
+	// then exit early with an ErrNodeNotFound.
-		pubKey := identity.SerializeCompressed()
+	pubKey := targetPub.SerializeCompressed()
 	nodeBytes := nodeMetaBucket.Get(pubKey)
 	if nodeBytes == nil {
-			return ErrNodeNotFound
+		return nil, ErrNodeNotFound
 	}
 
-		// Finally, decode an allocate a fresh LinkNode object to be
+	// Finally, decode and allocate a fresh LinkNode object to be returned
-		// returned to the caller.
+	// to the caller.
 	nodeReader := bytes.NewReader(nodeBytes)
-		node, err = deserializeLinkNode(nodeReader)
+	return deserializeLinkNode(nodeReader)
-		return err
-	})
-	if err != nil {
-		return nil, err
-	}
-
-	return node, nil
 }
 
+// TODO(roasbeef): update link node addrs in server upon connection
+
 // FetchAllLinkNodes starts a new database transaction to fetch all nodes with
 // whom we have active channels with.
 func (db *DB) FetchAllLinkNodes() ([]*LinkNode, error) {