initial import from /x/ monorepo

Signed-off-by: Xe Iaso <me@xeiaso.net>

cmd/anubis/internal/config/config.go

@@ -0,0 +1,99 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+)
+
+type Rule string
+
+const (
+	RuleUnknown   = ""
+	RuleAllow     = "ALLOW"
+	RuleDeny      = "DENY"
+	RuleChallenge = "CHALLENGE"
+)
+
+type Bot struct {
+	Name           string  `json:"name"`
+	UserAgentRegex *string `json:"user_agent_regex"`
+	PathRegex      *string `json:"path_regex"`
+	Action         Rule    `json:"action"`
+}
+
+var (
+	ErrNoBotRulesDefined                 = errors.New("config: must define at least one (1) bot rule")
+	ErrBotMustHaveName                   = errors.New("config.Bot: must set name")
+	ErrBotMustHaveUserAgentOrPath        = errors.New("config.Bot: must set either user_agent_regex, path_regex")
+	ErrBotMustHaveUserAgentOrPathNotBoth = errors.New("config.Bot: must set either user_agent_regex, path_regex, and not both")
+	ErrUnknownAction                     = errors.New("config.Bot: unknown action")
+	ErrInvalidUserAgentRegex             = errors.New("config.Bot: invalid user agent regex")
+	ErrInvalidPathRegex                  = errors.New("config.Bot: invalid path regex")
+)
+
+func (b Bot) Valid() error {
+	var errs []error
+
+	if b.Name == "" {
+		errs = append(errs, ErrBotMustHaveName)
+	}
+
+	if b.UserAgentRegex == nil && b.PathRegex == nil {
+		errs = append(errs, ErrBotMustHaveUserAgentOrPath)
+	}
+
+	if b.UserAgentRegex != nil && b.PathRegex != nil {
+		errs = append(errs, ErrBotMustHaveUserAgentOrPathNotBoth)
+	}
+
+	if b.UserAgentRegex != nil {
+		if _, err := regexp.Compile(*b.UserAgentRegex); err != nil {
+			errs = append(errs, ErrInvalidUserAgentRegex, err)
+		}
+	}
+
+	if b.PathRegex != nil {
+		if _, err := regexp.Compile(*b.PathRegex); err != nil {
+			errs = append(errs, ErrInvalidPathRegex, err)
+		}
+	}
+
+	switch b.Action {
+	case RuleAllow, RuleChallenge, RuleDeny:
+		// okay
+	default:
+		errs = append(errs, fmt.Errorf("%w: %q", ErrUnknownAction, b.Action))
+	}
+
+	if len(errs) != 0 {
+		return fmt.Errorf("config: bot entry for %q is not valid:\n%w", b.Name, errors.Join(errs...))
+	}
+
+	return nil
+}
+
+type Config struct {
+	Bots  []Bot `json:"bots"`
+	DNSBL bool  `json:"dnsbl"`
+}
+
+func (c Config) Valid() error {
+	var errs []error
+
+	if len(c.Bots) == 0 {
+		errs = append(errs, ErrNoBotRulesDefined)
+	}
+
+	for _, b := range c.Bots {
+		if err := b.Valid(); err != nil {
+			errs = append(errs, err)
+		}
+	}
+
+	if len(errs) != 0 {
+		return fmt.Errorf("config is not valid:\n%w", errors.Join(errs...))
+	}
+
+	return nil
+}