changes to OPER command

* Impose a throttle on OPER attempts regardless of whether they caused a
  password check.
* Never disconnect the client on a failed attempt, even if there was a
  password check.
* Change error numeric to ERR_NOOPERHOST
* Explicit information about the failure in the server log (copying Insp)

Fixes #2296.

default.yaml

@@ -358,6 +358,10 @@ server:
     secure-nets:
         # - "10.0.0.0/8"
 
+    # allow attempts to OPER with a password at most this often. default to
+    # 10 seconds when unset.
+    oper-throttle: 10s
+
     # Ergo will write files to disk under certain circumstances, e.g.,
     # CPU profiling or data export. by default, these files will be written
     # to the working directory. set this to customize:

docs/MANUAL.md

@@ -527,7 +527,7 @@ If your client or bot is failing to connect to Ergo, here are some things to che
 
 ## Why can't I oper?
 
-If you try to oper unsuccessfully, Ergo will disconnect you from the network. If you're unable to oper, here are some things to double-check:
+If your `OPER` command fails, check your server logs for more information. Here are some general issues to double-check:
 
 1. Did you correctly generate the hashed password with `ergo genpasswd`?
 1. Did you add the password hash to the correct config file, then save the file?

irc/client.go

@@ -189,6 +189,8 @@ type Session struct {
 	fakelag              Fakelag
 	deferredFakelagCount int
 
+	lastOperAttempt time.Time
+
 	certfp     string
 	peerCerts  []*x509.Certificate
 	sasl       saslStatus

irc/config.go

@@ -599,6 +599,7 @@ type Config struct {
 		Cloaks                   cloaks.CloakConfig              `yaml:"ip-cloaking"`
 		SecureNetDefs            []string                        `yaml:"secure-nets"`
 		secureNets               []net.IPNet
+		OperThrottle             time.Duration `yaml:"oper-throttle"`
 		supportedCaps            *caps.Set
 		supportedCapsWithoutSTS  *caps.Set
 		capValues                caps.Values
@@ -1480,6 +1481,10 @@ func LoadConfig(filename string) (config *Config, err error) {
 		config.Server.supportedCaps.Disable(caps.SASL)
 	}
 
+	if config.Server.OperThrottle <= 0 {
+		config.Server.OperThrottle = 10 * time.Second
+	}
+
 	if err := config.Accounts.OAuth2.Postprocess(); err != nil {
 		return nil, err
 	}

irc/handlers.go

@@ -2545,8 +2545,19 @@ func operHandler(server *Server, client *Client, msg ircmsg.Message, rb *Respons
 		return false
 	}
 
+	config := server.Config()
+	now := time.Now()
+	nextAllowableAttempt := rb.session.lastOperAttempt.Add(config.Server.OperThrottle)
+	if now.Before(nextAllowableAttempt) {
+		timeLeft := nextAllowableAttempt.Sub(now).Round(time.Millisecond)
+		rb.Add(nil, server.name, ERR_NOOPERHOST, client.Nick(), fmt.Sprintf(client.t("You must wait %v before issuing OPER again"), timeLeft))
+		return false
+	}
+
+	rb.session.lastOperAttempt = now
+
 	// must pass at least one check, and all enabled checks
-	var checkPassed, checkFailed, passwordFailed bool
+	var checkPassed, checkFailed, certFailed, passwordFailed bool
 	oper := server.GetOperator(msg.Params[0])
 	if oper != nil {
 		if oper.Certfp != "" {
@@ -2554,11 +2565,13 @@ func operHandler(server *Server, client *Client, msg ircmsg.Message, rb *Respons
 				checkPassed = true
 			} else {
 				checkFailed = true
+				certFailed = true
 			}
 		}
 		if !checkFailed && oper.Pass != nil {
 			if len(msg.Params) == 1 {
 				checkFailed = true
+				passwordFailed = true
 			} else if bcrypt.CompareHashAndPassword(oper.Pass, []byte(msg.Params[1])) != nil {
 				checkFailed = true
 				passwordFailed = true
@@ -2569,14 +2582,21 @@ func operHandler(server *Server, client *Client, msg ircmsg.Message, rb *Respons
 	}
 
 	if !checkPassed || checkFailed {
-		rb.Add(nil, server.name, ERR_PASSWDMISMATCH, client.Nick(), client.t("Password incorrect"))
-		// #951: only disconnect them if we actually tried to check a password for them
-		if passwordFailed {
-			client.Quit(client.t("Password incorrect"), rb.session)
-			return true
+		rb.Add(nil, server.name, ERR_NOOPERHOST, client.Nick(), client.t("OPER failed; check the server logs for details."))
+
+		// hopefully not too spammy given the throttling:
+		if oper == nil {
+			server.logger.Info("opers", "OPER failed with invalid oper name", msg.Params[0])
+		} else if certFailed {
+			server.logger.Info("opers", "OPER attempt for", msg.Params[0], "failed with invalid certfp")
+		} else if passwordFailed {
+			server.logger.Info("opers", "OPER attempt for", msg.Params[0], "failed with invalid password")
 		} else {
-			return false
+			// should not be possible given config validation
+			server.logger.Info("opers", "OPER attempt for", msg.Params[0], "failed with invalid config")
 		}
+
+		return false
 	}
 
 	if oper != nil {

traditional.yaml

@@ -330,6 +330,10 @@ server:
     secure-nets:
         # - "10.0.0.0/8"
 
+    # allow attempts to OPER with a password at most this often. default to
+    # 10 seconds when unset.
+    oper-throttle: 10s
+
     # Ergo will write files to disk under certain circumstances, e.g.,
     # CPU profiling or data export. by default, these files will be written
     # to the working directory. set this to customize: