fix #1020

conventional.yaml

@@ -330,6 +330,10 @@ accounts:
     # PASS as well, so it can be configured to authenticate with SASL only.
     skip-server-password: false
 
+    # enable login to accounts via the PASS command, e.g., PASS account:password
+    # this is sometimes useful for compatibility with old clients that don't support SASL
+    login-via-pass-command: false
+
     # require-sasl controls whether clients are required to have accounts
     # (and sign into them using SASL) to connect to the server
     require-sasl:

irc/client.go

@@ -97,6 +97,15 @@ func (s *saslStatus) Clear() {
 	*s = saslStatus{}
 }
 
+// what stage the client is at w.r.t. the PASS command:
+type serverPassStatus uint
+
+const (
+	serverPassUnsent serverPassStatus = iota
+	serverPassSuccessful
+	serverPassFailed
+)
+
 // Session is an individual client connection to the server (TCP connection
 // and associated per-connection data, such as capabilities). There is a
 // many-one relationship between sessions and clients.
@@ -117,9 +126,9 @@ type Session struct {
 	deferredFakelagCount int
 	destroyed            uint32
 
-	certfp          string
-	sasl            saslStatus
-	sentPassCommand bool
+	certfp     string
+	sasl       saslStatus
+	passStatus serverPassStatus
 
 	batchCounter uint32
 
@@ -510,7 +519,7 @@ const (
 func (client *Client) isAuthorized(config *Config, session *Session) AuthOutcome {
 	saslSent := client.account != ""
 	// PASS requirement
-	if (config.Server.passwordBytes != nil) && !session.sentPassCommand && !(config.Accounts.SkipServerPassword && saslSent) {
+	if (config.Server.passwordBytes != nil) && session.passStatus != serverPassSuccessful && !(config.Accounts.SkipServerPassword && saslSent) {
 		return authFailPass
 	}
 	// Tor connections may be required to authenticate with SASL

irc/config.go

@@ -254,12 +254,13 @@ type AccountConfig struct {
 		Exempted     []string
 		exemptedNets []net.IPNet
 	} `yaml:"require-sasl"`
-	DefaultUserModes   *string `yaml:"default-user-modes"`
-	defaultUserModes   modes.ModeChanges
-	LDAP               ldap.ServerConfig
-	LoginThrottling    ThrottleConfig `yaml:"login-throttling"`
-	SkipServerPassword bool           `yaml:"skip-server-password"`
-	NickReservation    struct {
+	DefaultUserModes    *string `yaml:"default-user-modes"`
+	defaultUserModes    modes.ModeChanges
+	LDAP                ldap.ServerConfig
+	LoginThrottling     ThrottleConfig `yaml:"login-throttling"`
+	SkipServerPassword  bool           `yaml:"skip-server-password"`
+	LoginViaPassCommand bool           `yaml:"login-via-pass-command"`
+	NickReservation     struct {
 		Enabled                bool
 		AdditionalNickLimit    int `yaml:"additional-nick-limit"`
 		Method                 NickEnforcementMethod
@@ -1078,6 +1079,9 @@ func LoadConfig(filename string) (config *Config, err error) {
 		if err != nil {
 			return nil, err
 		}
+		if config.Accounts.LoginViaPassCommand && !config.Accounts.SkipServerPassword {
+			return nil, errors.New("Using a server password and login-via-pass-command requires skip-server-password as well")
+		}
 	}
 
 	if config.Accounts.Registration.BcryptCost == 0 {

irc/handlers.go

@@ -2159,16 +2159,45 @@ func passHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 		rb.Add(nil, server.name, ERR_ALREADYREGISTRED, client.nick, client.t("You may not reregister"))
 		return false
 	}
+	if rb.session.passStatus != serverPassUnsent {
+		return false
+	}
+
+	password := msg.Params[0]
+	config := server.Config()
+
+	if config.Accounts.LoginViaPassCommand {
+		colonIndex := strings.IndexByte(password, ':')
+		if colonIndex != -1 && client.Account() == "" {
+			// TODO consolidate all login throttle checks into AccountManager
+			throttled, _ := client.loginThrottle.Touch()
+			if !throttled {
+				account, accountPass := password[:colonIndex], password[colonIndex+1:]
+				err := server.accounts.AuthenticateByPassphrase(client, account, accountPass)
+				if err == nil {
+					sendSuccessfulAccountAuth(client, rb, false, true)
+					// login-via-pass-command entails that we do not need to check
+					// an actual server password (either no password or skip-server-password)
+					rb.session.passStatus = serverPassSuccessful
+					return false
+				}
+			}
+		}
+	}
+
+	serverPassword := config.Server.passwordBytes
 
 	// if no password exists, skip checking
-	serverPassword := server.Config().Server.passwordBytes
 	if serverPassword == nil {
 		return false
 	}
 
 	// check the provided password
-	password := []byte(msg.Params[0])
-	rb.session.sentPassCommand = bcrypt.CompareHashAndPassword(serverPassword, password) == nil
+	if bcrypt.CompareHashAndPassword(serverPassword, []byte(password)) == nil {
+		rb.session.passStatus = serverPassSuccessful
+	} else {
+		rb.session.passStatus = serverPassFailed
+	}
 
 	// if they failed the check, we'll bounce them later when they try to complete registration
 	return false

oragono.yaml

@@ -351,6 +351,10 @@ accounts:
     # PASS as well, so it can be configured to authenticate with SASL only.
     skip-server-password: false
 
+    # enable login to accounts via the PASS command, e.g., PASS account:password
+    # this is sometimes useful for compatibility with old clients that don't support SASL
+    login-via-pass-command: false
+
     # require-sasl controls whether clients are required to have accounts
     # (and sign into them using SASL) to connect to the server
     require-sasl: