dline: Prevent opers from banning themselves

irc/dline.go

 	return false, nil
 }
 
-// DLINE [duration] <ip>/<net> [ON <server>] [reason [| oper reason]]
+// DLINE [MYSELF] [duration] <ip>/<net> [ON <server>] [reason [| oper reason]]
 func dlineHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
 	// check oper permissions
 	if !client.class.Capabilities["oper:local_ban"] {
 
 	currentArg := 0
 
+	// when setting a ban that covers the oper's current connection, we require them to say
+	// "DLINE MYSELF" so that we're sure they really mean it.
+	var dlineMyself bool
+	if len(msg.Params) > currentArg+1 && strings.ToLower(msg.Params[currentArg]) == "myself" {
+		dlineMyself = true
+		currentArg++
+	}
+
 	// duration
 	duration, err := time.ParseDuration(msg.Params[currentArg])
 	durationIsUsed := err == nil
 
 	if hostNet == nil {
 		hostString = hostAddr.String()
+		if !dlineMyself && hostAddr.Equal(net.ParseIP(IPString(client.socket.conn.RemoteAddr()))) {
+			client.Send(nil, server.name, ERR_UNKNOWNERROR, client.nick, msg.Command, "This ban matches you. To DLINE yourself, you must pass use the command:  /DLINE MYSELF <arguments>")
+			return false
+		}
 	} else {
 		hostString = hostNet.String()
+		if !dlineMyself && hostNet.Contains(net.ParseIP(IPString(client.socket.conn.RemoteAddr()))) {
+			client.Send(nil, server.name, ERR_UNKNOWNERROR, client.nick, msg.Command, "This ban matches you. To DLINE yourself, you must pass use the command:  /DLINE MYSELF <arguments>")
+			return false
+		}
 	}
 
 	// check remote

irc/help.go

 	},
 	"dline": {
 		oper: true,
-		text: `DLINE [duration] <ip>/<net> [ON <server>] [reason [| oper reason]]
+		text: `DLINE [MYSELF] [duration] <ip>/<net> [ON <server>] [reason [| oper reason]]
 
 Bans an IP address or network from connecting to the server. If the duration is
 given then only for that long. The reason is shown to the user themselves, but
 
 Bans are saved across subsequent launches of the server.
 
+"MYSELF" is required when the DLINE matches the address the person applying it is connected
+from. If "MYSELF" is not given, trying to DLINE yourself will result in an error.
+
 [duration] can be of the following forms:
 	10h 8m 13s
 
 	127.0.0.1/8
 	8.8.8.8/24
 
+ON <server> specifies that the ban is to be set on that specific server.
+
 [reason] and [oper reason], if they exist, are separated by a vertical bar (|).`,
 	},
 	"help": {