Add ACME EAB support

docs/configuration/shared/tls.md

@@ -21,7 +21,11 @@
     "disable_http_challenge": false,
     "disable_tls_alpn_challenge": false,
     "alternative_http_port": 0,
-    "alternative_tls_port": 0
+    "alternative_tls_port": 0,
+    "external_account": {
+      "key_id": "",
+      "mac_key": ""
+    }
   }
 }
 ```
@@ -205,4 +209,23 @@ succeed.
 
 ### Reload
 
-For server configuration, certificate and key will be automatically reloaded if modified.
+For server configuration, certificate and key will be automatically reloaded if modified.
+
+#### external_account
+
+EAB (External Account Binding) contains information necessary to bind or map an ACME account to some other account known
+by the CA.
+
+External account bindings are "used to associate an ACME account with an existing account in a non-ACME system, such as
+a CA customer database.
+
+To enable ACME account binding, the CA operating the ACME server needs to provide the ACME client with a MAC key and a
+key identifier, using some mechanism outside of ACME. §7.3.4
+
+#### external_account.key_id
+
+The key identifier.
+
+#### external_account.mac_key
+
+The MAC key.

go.mod

@@ -15,6 +15,7 @@ require (
 	github.com/gorilla/websocket v1.5.0
 	github.com/hashicorp/yamux v0.1.1
 	github.com/logrusorgru/aurora v2.0.3+incompatible
+	github.com/mholt/acmez v1.0.4
 	github.com/oschwald/maxminddb-golang v1.10.0
 	github.com/pires/go-proxyproto v0.6.2
 	github.com/sagernet/certmagic v0.0.0-20220819042630-4a57f8b6853a
@@ -51,7 +52,6 @@ require (
 	github.com/marten-seemann/qpack v0.2.1 // indirect
 	github.com/marten-seemann/qtls-go1-18 v0.1.2 // indirect
 	github.com/marten-seemann/qtls-go1-19 v0.1.0 // indirect
-	github.com/mholt/acmez v1.0.4 // indirect
 	github.com/nxadm/tail v1.4.8 // indirect
 	github.com/onsi/ginkgo v1.16.5 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect

inbound/tls_acme.go

@@ -11,6 +11,8 @@ import (
 	"github.com/sagernet/sing-box/adapter"
 	"github.com/sagernet/sing-box/option"
 	E "github.com/sagernet/sing/common/exceptions"
+
+	"github.com/mholt/acmez/acme"
 )
 
 type acmeWrapper struct {
@@ -53,17 +55,19 @@ func startACME(ctx context.Context, options option.InboundACMEOptions) (*tls.Con
 		DefaultServerName: options.DefaultServerName,
 		Storage:           storage,
 	}
-	config.Issuers = []certmagic.Issuer{
-		certmagic.NewACMEIssuer(config, certmagic.ACMEIssuer{
-			CA:                      acmeServer,
-			Email:                   options.Email,
-			Agreed:                  true,
-			DisableHTTPChallenge:    options.DisableHTTPChallenge,
-			DisableTLSALPNChallenge: options.DisableTLSALPNChallenge,
-			AltHTTPPort:             int(options.AlternativeHTTPPort),
-			AltTLSALPNPort:          int(options.AlternativeTLSPort),
-		}),
+	acmeConfig := certmagic.ACMEIssuer{
+		CA:                      acmeServer,
+		Email:                   options.Email,
+		Agreed:                  true,
+		DisableHTTPChallenge:    options.DisableHTTPChallenge,
+		DisableTLSALPNChallenge: options.DisableTLSALPNChallenge,
+		AltHTTPPort:             int(options.AlternativeHTTPPort),
+		AltTLSALPNPort:          int(options.AlternativeTLSPort),
+	}
+	if options.ExternalAccount != nil {
+		acmeConfig.ExternalAccount = (*acme.EAB)(options.ExternalAccount)
 	}
+	config.Issuers = []certmagic.Issuer{certmagic.NewACMEIssuer(config, acmeConfig)}
 	config = certmagic.New(certmagic.NewCache(certmagic.CacheOptions{
 		GetConfigForCert: func(certificate certmagic.Certificate) (*certmagic.Config, error) {
 			return config, nil

option/tls.go

@@ -20,18 +20,6 @@ type InboundTLSOptions struct {
 	ACME            *InboundACMEOptions `json:"acme,omitempty"`
 }
 
-type InboundACMEOptions struct {
-	Domain                  Listable[string] `json:"domain,omitempty"`
-	DataDirectory           string           `json:"data_directory,omitempty"`
-	DefaultServerName       string           `json:"default_server_name,omitempty"`
-	Email                   string           `json:"email,omitempty"`
-	Provider                string           `json:"provider,omitempty"`
-	DisableHTTPChallenge    bool             `json:"disable_http_challenge,omitempty"`
-	DisableTLSALPNChallenge bool             `json:"disable_tls_alpn_challenge,omitempty"`
-	AlternativeHTTPPort     uint16           `json:"alternative_http_port,omitempty"`
-	AlternativeTLSPort      uint16           `json:"alternative_tls_port,omitempty"`
-}
-
 type OutboundTLSOptions struct {
 	Enabled         bool             `json:"enabled,omitempty"`
 	DisableSNI      bool             `json:"disable_sni,omitempty"`

option/tls_acme.go

@@ -0,0 +1,19 @@
+package option
+
+type InboundACMEOptions struct {
+	Domain                  Listable[string]            `json:"domain,omitempty"`
+	DataDirectory           string                      `json:"data_directory,omitempty"`
+	DefaultServerName       string                      `json:"default_server_name,omitempty"`
+	Email                   string                      `json:"email,omitempty"`
+	Provider                string                      `json:"provider,omitempty"`
+	DisableHTTPChallenge    bool                        `json:"disable_http_challenge,omitempty"`
+	DisableTLSALPNChallenge bool                        `json:"disable_tls_alpn_challenge,omitempty"`
+	AlternativeHTTPPort     uint16                      `json:"alternative_http_port,omitempty"`
+	AlternativeTLSPort      uint16                      `json:"alternative_tls_port,omitempty"`
+	ExternalAccount         *ACMEExternalAccountOptions `json:"external_account,omitempty"`
+}
+
+type ACMEExternalAccountOptions struct {
+	KeyID  string `json:"key_id,omitempty"`
+	MACKey string `json:"mac_key,omitempty"`
+}