Add hysteria and acme TLS certificate issuer (#18)

* Add hysteria client/server
* Add acme TLS certificate issuer

inbound/tls_acme.go

@@ -0,0 +1,66 @@
+//go:build with_acme
+
+package inbound
+
+import (
+	"context"
+	"crypto/tls"
+	"strings"
+
+	"github.com/sagernet/certmagic"
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+type acmeWrapper struct {
+	ctx    context.Context
+	cfg    *certmagic.Config
+	domain []string
+}
+
+func (w *acmeWrapper) Start() error {
+	return w.cfg.ManageSync(w.ctx, w.domain)
+}
+
+func (w *acmeWrapper) Close() error {
+	w.cfg.Unmanage(w.domain)
+	return nil
+}
+
+func startACME(ctx context.Context, options option.InboundACMEOptions) (*tls.Config, adapter.Service, error) {
+	var acmeServer string
+	switch options.Provider {
+	case "", "letsencrypt":
+		acmeServer = certmagic.LetsEncryptProductionCA
+	case "zerossl":
+		acmeServer = certmagic.ZeroSSLProductionCA
+	default:
+		if !strings.HasPrefix(options.Provider, "https://") {
+			return nil, nil, E.New("unsupported acme provider: " + options.Provider)
+		}
+		acmeServer = options.Provider
+	}
+	var storage certmagic.Storage
+	if options.DataDirectory != "" {
+		storage = &certmagic.FileStorage{
+			Path: options.DataDirectory,
+		}
+	}
+	config := certmagic.New(certmagic.NewCache(certmagic.CacheOptions{}), certmagic.Config{
+		DefaultServerName: options.DefaultServerName,
+		Issuers: []certmagic.Issuer{
+			&certmagic.ACMEIssuer{
+				CA:                      acmeServer,
+				Email:                   options.Email,
+				Agreed:                  true,
+				DisableHTTPChallenge:    options.DisableHTTPChallenge,
+				DisableTLSALPNChallenge: options.DisableTLSALPNChallenge,
+				AltHTTPPort:             int(options.AlternativeHTTPPort),
+				AltTLSALPNPort:          int(options.AlternativeTLSPort),
+			},
+		},
+		Storage: storage,
+	})
+	return config.TLSConfig(), &acmeWrapper{ctx, config, options.Domain}, nil
+}