credentials/tls: Use Go cipher suites to find TLS suite string name (#6709)

Author: bcr

credentials/tls.go

@@ -44,10 +44,25 @@ func (t TLSInfo) AuthType() string {
 	return "tls"
 }
 
+// cipherSuiteLookup returns the string version of a TLS cipher suite ID.
+func cipherSuiteLookup(cipherSuiteID uint16) string {
+	for _, s := range tls.CipherSuites() {
+		if s.ID == cipherSuiteID {
+			return s.Name
+		}
+	}
+	for _, s := range tls.InsecureCipherSuites() {
+		if s.ID == cipherSuiteID {
+			return s.Name
+		}
+	}
+	return fmt.Sprintf("unknown ID: %v", cipherSuiteID)
+}
+
 // GetSecurityValue returns security info requested by channelz.
 func (t TLSInfo) GetSecurityValue() ChannelzSecurityValue {
 	v := &TLSChannelzSecurityValue{
-		StandardName: cipherSuiteLookup[t.State.CipherSuite],
+		StandardName: cipherSuiteLookup(t.State.CipherSuite),
 	}
 	// Currently there's no way to get LocalCertificate info from tls package.
 	if len(t.State.PeerCertificates) > 0 {
@@ -205,32 +220,3 @@ type TLSChannelzSecurityValue struct {
 	LocalCertificate  []byte
 	RemoteCertificate []byte
 }
-
-var cipherSuiteLookup = map[uint16]string{
-	tls.TLS_RSA_WITH_RC4_128_SHA:                "TLS_RSA_WITH_RC4_128_SHA",
-	tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA:           "TLS_RSA_WITH_3DES_EDE_CBC_SHA",
-	tls.TLS_RSA_WITH_AES_128_CBC_SHA:            "TLS_RSA_WITH_AES_128_CBC_SHA",
-	tls.TLS_RSA_WITH_AES_256_CBC_SHA:            "TLS_RSA_WITH_AES_256_CBC_SHA",
-	tls.TLS_RSA_WITH_AES_128_GCM_SHA256:         "TLS_RSA_WITH_AES_128_GCM_SHA256",
-	tls.TLS_RSA_WITH_AES_256_GCM_SHA384:         "TLS_RSA_WITH_AES_256_GCM_SHA384",
-	tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA:        "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA:    "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA:    "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA:          "TLS_ECDHE_RSA_WITH_RC4_128_SHA",
-	tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA:     "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA:      "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:      "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256:   "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
-	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384:   "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
-	tls.TLS_FALLBACK_SCSV:                       "TLS_FALLBACK_SCSV",
-	tls.TLS_RSA_WITH_AES_128_CBC_SHA256:         "TLS_RSA_WITH_AES_128_CBC_SHA256",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256",
-	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256:   "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256",
-	tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305:    "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305",
-	tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305:  "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305",
-	tls.TLS_AES_128_GCM_SHA256:                  "TLS_AES_128_GCM_SHA256",
-	tls.TLS_AES_256_GCM_SHA384:                  "TLS_AES_256_GCM_SHA384",
-	tls.TLS_CHACHA20_POLY1305_SHA256:            "TLS_CHACHA20_POLY1305_SHA256",
-}