accessman: only check ban score for restricted peers

If a peer has, or used to have a channel with us there's no need to
check for the ban score.

Author: yyforyongyu

accessman.go

@@ -93,27 +93,9 @@ func (a *accessMan) assignPeerPerms(remotePub *btcec.PublicKey) (
 	// Default is restricted unless the below filters say otherwise.
 	access := peerStatusRestricted
 
-	shouldDisconnect, err := a.cfg.shouldDisconnect(remotePub)
-	if err != nil {
-		acsmLog.ErrorS(ctx, "Error checking disconnect status", err)
-
-		// Access is restricted here.
-		return access, err
-	}
-
-	if shouldDisconnect {
-		acsmLog.WarnS(ctx, "Peer is banned, assigning restricted access",
-			ErrGossiperBan)
-
-		// Access is restricted here.
-		return access, ErrGossiperBan
-	}
-
 	// Lock banScoreMtx for reading so that we can update the banning maps
 	// below.
 	a.banScoreMtx.RLock()
-	defer a.banScoreMtx.RUnlock()
-
 	if count, found := a.peerCounts[peerMapKey]; found {
 		if count.HasOpenOrClosedChan {
 			acsmLog.DebugS(ctx, "Peer has open/closed channel, "+
@@ -127,23 +109,45 @@ func (a *accessMan) assignPeerPerms(remotePub *btcec.PublicKey) (
 			access = peerStatusTemporary
 		}
 	}
+	a.banScoreMtx.RUnlock()
+
+	// Exit early if the peer status is no longer restricted.
+	if access != peerStatusRestricted {
+		return access, nil
+	}
+
+	// Check whether this peer is banned.
+	shouldDisconnect, err := a.cfg.shouldDisconnect(remotePub)
+	if err != nil {
+		acsmLog.ErrorS(ctx, "Error checking disconnect status", err)
+
+		// Access is restricted here.
+		return access, err
+	}
+
+	if shouldDisconnect {
+		acsmLog.WarnS(ctx, "Peer is banned, assigning restricted access",
+			ErrGossiperBan)
+
+		// Access is restricted here.
+		return access, ErrGossiperBan
+	}
 
 	// If we've reached this point and access hasn't changed from
 	// restricted, then we need to check if we even have a slot for this
 	// peer.
-	if access == peerStatusRestricted {
-		acsmLog.DebugS(ctx, "Peer has no channels, assigning "+
-			"restricted access")
+	acsmLog.DebugS(ctx, "Peer has no channels, assigning restricted access")
 
-		if a.numRestricted >= a.cfg.maxRestrictedSlots {
-			acsmLog.WarnS(ctx, "No more restricted slots "+
-				"available, denying peer",
-				ErrNoMoreRestrictedAccessSlots,
-				"num_restricted", a.numRestricted,
-				"max_restricted", a.cfg.maxRestrictedSlots)
+	a.banScoreMtx.RLock()
+	defer a.banScoreMtx.RUnlock()
 
-			return access, ErrNoMoreRestrictedAccessSlots
-		}
+	if a.numRestricted >= a.cfg.maxRestrictedSlots {
+		acsmLog.WarnS(ctx, "No more restricted slots available, "+
+			"denying peer", ErrNoMoreRestrictedAccessSlots,
+			"num_restricted", a.numRestricted, "max_restricted",
+			a.cfg.maxRestrictedSlots)
+
+		return access, ErrNoMoreRestrictedAccessSlots
 	}
 
 	return access, nil