fix #1997 (#2088)

* Fix #1997 (allow the use of an external file for the email blacklist)
* Change config key names for blacklist (compatibility break)
* Accept globs rather than regexes for blacklist by default
* Blacklist comparison is now case-insensitive

default.yaml

@@ -418,8 +418,13 @@ accounts:
             #     username: "admin"
             #     password: "hunter2"
             #     implicit-tls: false # TLS from the first byte, typically on port 465
-            blacklist-regexes:
-            #    - ".*@mailinator.com"
+            # addresses that are not accepted for registration:
+            address-blacklist:
+            #    - "*@mailinator.com"
+            address-blacklist-syntax: "glob" # change to "regex" for regular expressions
+            # file of newline-delimited address blacklist entries in the above syntax;
+            # supersedes address-blacklist if set:
+            # address-blacklist-file: "/path/to/address-blacklist-file"
             timeout: 60s
             # email-based password reset:
             password-reset:

irc/email/email.go

@@ -4,10 +4,13 @@
 package email
 
 import (
+	"bufio"
 	"bytes"
 	"errors"
 	"fmt"
+	"io"
 	"net"
+	"os"
 	"regexp"
 	"strings"
 	"time"
@@ -23,6 +26,38 @@ var (
 	ErrNoMXRecord         = errors.New("Couldn't resolve MX record")
 )
 
+type BlacklistSyntax uint
+
+const (
+	BlacklistSyntaxGlob BlacklistSyntax = iota
+	BlacklistSyntaxRegexp
+)
+
+func blacklistSyntaxFromString(status string) (BlacklistSyntax, error) {
+	switch strings.ToLower(status) {
+	case "glob", "":
+		return BlacklistSyntaxGlob, nil
+	case "re", "regex", "regexp":
+		return BlacklistSyntaxRegexp, nil
+	default:
+		return BlacklistSyntaxRegexp, fmt.Errorf("Unknown blacklist syntax type `%s`", status)
+	}
+}
+
+func (bs *BlacklistSyntax) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var orig string
+	var err error
+	if err = unmarshal(&orig); err != nil {
+		return err
+	}
+	if result, err := blacklistSyntaxFromString(orig); err == nil {
+		*bs = result
+		return nil
+	} else {
+		return err
+	}
+}
+
 type MTAConfig struct {
 	Server      string
 	Port        int
@@ -43,7 +78,9 @@ type MailtoConfig struct {
 	VerifyMessageSubject   string `yaml:"verify-message-subject"`
 	DKIM                   DKIMConfig
 	MTAReal                MTAConfig       `yaml:"mta"`
-	BlacklistRegexes     []string  `yaml:"blacklist-regexes"`
+	AddressBlacklist       []string        `yaml:"address-blacklist"`
+	AddressBlacklistSyntax BlacklistSyntax `yaml:"address-blacklist-syntax"`
+	AddressBlacklistFile   string          `yaml:"address-blacklist-file"`
 	blacklistRegexes       []*regexp.Regexp
 	Timeout                time.Duration
 	PasswordReset          struct {
@@ -53,6 +90,44 @@ type MailtoConfig struct {
 	} `yaml:"password-reset"`
 }
 
+func (config *MailtoConfig) compileBlacklistEntry(source string) (re *regexp.Regexp, err error) {
+	if config.AddressBlacklistSyntax == BlacklistSyntaxGlob {
+		return utils.CompileGlob(source, false)
+	} else {
+		return regexp.Compile(fmt.Sprintf("^%s$", source))
+	}
+}
+
+func (config *MailtoConfig) processBlacklistFile(filename string) (result []*regexp.Regexp, err error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	reader := bufio.NewReader(f)
+	lineNo := 0
+	for {
+		line, err := reader.ReadString('\n')
+		lineNo++
+		line = strings.TrimSpace(line)
+		if line != "" && line[0] != '#' {
+			if compiled, compileErr := config.compileBlacklistEntry(line); compileErr == nil {
+				result = append(result, compiled)
+			} else {
+				return result, fmt.Errorf("Failed to compile line %d of blacklist-regex-file `%s`: %w", lineNo, line, compileErr)
+			}
+		}
+		switch err {
+		case io.EOF:
+			return result, nil
+		case nil:
+			continue
+		default:
+			return result, err
+		}
+	}
+}
+
 func (config *MailtoConfig) Postprocess(heloDomain string) (err error) {
 	if config.Sender == "" {
 		return errors.New("Invalid mailto sender address")
@@ -68,13 +143,21 @@ func (config *MailtoConfig) Postprocess(heloDomain string) (err error) {
 		config.HeloDomain = heloDomain
 	}
 
-	for _, reg := range config.BlacklistRegexes {
-		compiled, err := regexp.Compile(fmt.Sprintf("^%s$", reg))
+	if config.AddressBlacklistFile != "" {
+		config.blacklistRegexes, err = config.processBlacklistFile(config.AddressBlacklistFile)
+		if err != nil {
+			return err
+		}
+	} else if len(config.AddressBlacklist) != 0 {
+		config.blacklistRegexes = make([]*regexp.Regexp, 0, len(config.AddressBlacklist))
+		for _, reg := range config.AddressBlacklist {
+			compiled, err := config.compileBlacklistEntry(reg)
 			if err != nil {
 				return err
 			}
 			config.blacklistRegexes = append(config.blacklistRegexes, compiled)
 		}
+	}
 
 	if config.MTAConfig.Server != "" {
 		// smarthost, nothing more to validate
@@ -118,8 +201,9 @@ func ComposeMail(config MailtoConfig, recipient, subject string) (message bytes.
 }
 
 func SendMail(config MailtoConfig, recipient string, msg []byte) (err error) {
+	recipientLower := strings.ToLower(recipient)
 	for _, reg := range config.blacklistRegexes {
-		if reg.MatchString(recipient) {
+		if reg.MatchString(recipientLower) {
 			return ErrBlacklistedAddress
 		}
 	}

traditional.yaml

@@ -391,8 +391,13 @@ accounts:
             #     username: "admin"
             #     password: "hunter2"
             #     implicit-tls: false # TLS from the first byte, typically on port 465
-            blacklist-regexes:
-            #    - ".*@mailinator.com"
+            # addresses that are not accepted for registration:
+            address-blacklist:
+            #    - "*@mailinator.com"
+            address-blacklist-syntax: "glob" # change to "regex" for regular expressions
+            # file of newline-delimited address blacklist entries in the above syntax;
+            # supersedes address-blacklist if set:
+            # address-blacklist-file: "/path/to/address-blacklist-file"
             timeout: 60s
             # email-based password reset:
             password-reset: