feat: add initial implementation of osiris, the TLS terminator for Anubis

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

cmd/osiris/internal/config/domain.go

@@ -0,0 +1,65 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+
+	"golang.org/x/net/idna"
+)
+
+var (
+	ErrInvalidDomainName      = errors.New("domain: name is invalid")
+	ErrInvalidDomainTLSConfig = errors.New("domain: TLS config is invalid")
+	ErrInvalidURL             = errors.New("invalid URL")
+	ErrInvalidURLScheme       = errors.New("URL has invalid scheme")
+)
+
+type Domain struct {
+	Name         string `hcl:"name,label"`
+	TLS          TLS    `hcl:"tls,block"`
+	Target       string `hcl:"target"`
+	HealthTarget string `hcl:"health_target"`
+}
+
+func (d Domain) Valid() error {
+	var errs []error
+
+	if _, err := idna.Lookup.ToASCII(d.Name); err != nil {
+		errs = append(errs, fmt.Errorf("%w %q: %w", ErrInvalidDomainName, d.Name, err))
+	}
+
+	if err := d.TLS.Valid(); err != nil {
+		errs = append(errs, fmt.Errorf("%w: %w", ErrInvalidDomainTLSConfig, err))
+	}
+
+	if err := isURLValid(d.Target); err != nil {
+		errs = append(errs, fmt.Errorf("target has %w %q: %w", ErrInvalidURL, d.Target, err))
+	}
+
+	if err := isURLValid(d.HealthTarget); err != nil {
+		errs = append(errs, fmt.Errorf("health_target has %w %q: %w", ErrInvalidURL, d.HealthTarget, err))
+	}
+
+	if len(errs) != 0 {
+		return errors.Join(errs...)
+	}
+
+	return nil
+}
+
+func isURLValid(input string) error {
+	u, err := url.Parse(input)
+	if err != nil {
+		return err
+	}
+
+	switch u.Scheme {
+	case "http", "https", "h2c", "unix":
+		// do nothing
+	default:
+		return fmt.Errorf("%w %s has scheme %s (want http, https, h2c, unix)", ErrInvalidURLScheme, input, u.Scheme)
+	}
+
+	return nil
+}