Refactor ban management behind BanMgr interface

Extract ban logic into a BanMgr interface with two implementations:
- BanFile: file-based YAML storage with support for IP, username, and
  nickname bans (backwards-compatible with legacy format)
- RedisBanMgr: Redis-backed implementation with permanent and temporary
  ban support, using fail-safe deny-on-error behavior

This replaces scattered Redis calls in API handlers, transaction
handlers, and server connection logic with unified interface calls,
removing the Redis dependency from the API server constructor and
enabling ban functionality for both file-only and Redis deployments.

1 files changed, 18 insertions, 22 deletions

diff --git a/hotline/server.go b/hotline/server.go
index d797c1e..545e84c 100644
--- a/hotline/server.go
+++ b/hotline/server.go
@@ -496,23 +496,17 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
 
 	// Check if remoteAddr is present in the ban list, we do this after we have the login name
 	ipAddr, _, _ := net.SplitHostPort(remoteAddr)
-	if s.Redis != nil {
-		// Redis-based ban check
-		bannedUser, _ := s.Redis.SIsMember(ctx, "mobius:banned:users", login).Result()
-		bannedIP, _ := s.Redis.SIsMember(ctx, "mobius:banned:ips", ipAddr).Result()
-		if bannedUser {
-			s.Redis.SAdd(ctx, "mobius:banned:ips", ipAddr)
-			sendBanMessage(rwc, "You are banned on this server")
-			s.Logger.Debug("Disconnecting banned user", "login", login, "ip", ipAddr)
-			return nil
-		}
-		if bannedIP {
-			sendBanMessage(rwc, "You are banned on this server")
-			s.Logger.Debug("Disconnecting banned IP", "ip", ipAddr)
-			return nil
-		}
-	} else {
-		// Fallback to in-memory ban list
+
+	// Check if user is banned
+	if s.BanList != nil && s.BanList.IsUsernameBanned(login) {
+		_ = s.BanList.Add(ipAddr, nil)
+		sendBanMessage(rwc, "You are banned on this server")
+		s.Logger.Debug("Disconnecting banned user", "login", login, "ip", ipAddr)
+		return nil
+	}
+
+	// Check if IP is banned
+	if s.BanList != nil {
 		if isBanned, banUntil := s.BanList.IsBanned(ipAddr); isBanned {
 			// permaban
 			if banUntil == nil {
@@ -531,16 +525,18 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
 
 	c := s.NewClientConn(rwc, remoteAddr)
 	// Add the client to the list of connected clients
+
+	// TODO: refactor this into a connection manager interface, maybe?
 	if s.Redis != nil {
-		s.Redis.SAdd(context.Background(), "mobius:online", login+"::"+ipAddr)
+		s.Redis.SAdd(context.Background(), RedisKeyOnline, login+"::"+ipAddr)
 	}
 
 	// Remove the client from the list of connected clients when they disconnect
 	defer func() {
 		if s.Redis != nil {
-			s.Redis.SRem(context.Background(), "mobius:online", login+"::"+ipAddr)
+			s.Redis.SRem(context.Background(), RedisKeyOnline, login+"::"+ipAddr)
 			if len(c.UserName) != 0 {
-				s.Redis.SRem(context.Background(), "mobius:online", login+":"+string(c.UserName)+":"+ipAddr)
+				s.Redis.SRem(context.Background(), RedisKeyOnline, login+":"+string(c.UserName)+":"+ipAddr)
 			}
 		}
 		c.Disconnect()
@@ -621,9 +617,9 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
 		// Update the Redis set with the new information
 		if s.Redis != nil && len(c.UserName) != 0 {
 			// Remove old entry (login::ip)
-			s.Redis.SRem(context.Background(), "mobius:online", login+"::"+ipAddr)
+			s.Redis.SRem(context.Background(), RedisKeyOnline, login+"::"+ipAddr)
 			// Add new entry with login, nickname, ip
-			s.Redis.SAdd(context.Background(), "mobius:online", login+":"+string(c.UserName)+":"+ipAddr)
+			s.Redis.SAdd(context.Background(), RedisKeyOnline, login+":"+string(c.UserName)+":"+ipAddr)
 		}
 
 		// Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this