ipn/ipnlocal: update PeerByID to return SelfNode and rename it to NodeByID (#16096)

Like NodeByKey, add an if stmt for checking the NodeId is SelfNode.

Updates #16052

Signed-off-by: Jerry Yan <792602257@qq.com>

ipn/ipnlocal/drive.go

@@ -318,7 +318,7 @@ func (b *LocalBackend) driveRemotesFromPeers(nm *netmap.NetworkMap) []*drive.Rem
 				// - They are online
 				// - They are allowed to share at least one folder with us
 				cn := b.currentNode()
-				peer, ok := cn.PeerByID(peerID)
+				peer, ok := cn.NodeByID(peerID)
 				if !ok {
 					return false
 				}

ipn/ipnlocal/local.go

@@ -1391,7 +1391,7 @@ func profileFromView(v tailcfg.UserProfileView) tailcfg.UserProfile {
 func (b *LocalBackend) WhoIsNodeKey(k key.NodePublic) (n tailcfg.NodeView, u tailcfg.UserProfile, ok bool) {
 	cn := b.currentNode()
 	if nid, ok := cn.NodeByKey(k); ok {
-		if n, ok := cn.PeerByID(nid); ok {
+		if n, ok := cn.NodeByID(nid); ok {
 			up, ok := cn.NetMap().UserProfiles[n.User()]
 			u = profileFromView(up)
 			return n, u, ok
@@ -1457,13 +1457,9 @@ func (b *LocalBackend) WhoIs(proto string, ipp netip.AddrPort) (n tailcfg.NodeVi
 	if nm == nil {
 		return failf("no netmap")
 	}
-	n, ok = cn.PeerByID(nid)
+	n, ok = cn.NodeByID(nid)
 	if !ok {
-		// Check if this the self-node, which would not appear in peers.
-		if !nm.SelfNode.Valid() || nid != nm.SelfNode.ID() {
-			return zero, u, false
-		}
-		n = nm.SelfNode
+	    return zero, u, false
 	}
 	up, ok := cn.UserByID(n.User())
 	if !ok {
@@ -1968,7 +1964,7 @@ func (b *LocalBackend) UpdateNetmapDelta(muts []netmap.NodeMutation) (handled bo
 			if !ok || mo.Online {
 				continue
 			}
-			n, ok := cn.PeerByID(m.NodeIDBeingMutated())
+			n, ok := cn.NodeByID(m.NodeIDBeingMutated())
 			if !ok || n.StableID() != exitNodeID {
 				continue
 			}
@@ -7724,7 +7720,7 @@ func (b *LocalBackend) srcIPHasCapForFilter(srcIP netip.Addr, cap tailcfg.NodeCa
 	if !ok {
 		return false
 	}
-	n, ok := cn.PeerByID(nodeID)
+	n, ok := cn.NodeByID(nodeID)
 	if !ok {
 		return false
 	}

ipn/ipnlocal/local_test.go

@@ -1005,7 +1005,7 @@ func TestUpdateNetmapDelta(t *testing.T) {
 		},
 	}
 	for _, want := range wants {
-		gotv, ok := b.currentNode().PeerByID(want.ID)
+		gotv, ok := b.currentNode().NodeByID(want.ID)
 		if !ok {
 			t.Errorf("netmap.Peer %v missing from b.profile.Peers", want.ID)
 			continue

ipn/ipnlocal/node_backend.go

@@ -206,9 +206,14 @@ func (nb *nodeBackend) NodeByKey(k key.NodePublic) (_ tailcfg.NodeID, ok bool) {
 	return 0, false
 }
 
-func (nb *nodeBackend) PeerByID(id tailcfg.NodeID) (_ tailcfg.NodeView, ok bool) {
+func (nb *nodeBackend) NodeByID(id tailcfg.NodeID) (_ tailcfg.NodeView, ok bool) {
 	nb.mu.Lock()
 	defer nb.mu.Unlock()
+	if nb.netMap != nil {
+		if self := nb.netMap.SelfNode; self.Valid() && self.ID() == id {
+			return self, true
+		}
+	}
 	n, ok := nb.peers[id]
 	return n, ok
 }