Limited cipher suite set in tls.Config to one which supports both Golang and iOS

cmd/pulse/main.go

@@ -357,7 +357,8 @@ func pulseMain() {
 	}
 
 	// The TLS configuration is used for both the listening socket and outgoing
-	// connections.
+	// connections. Includes a set of cipher suites supported by both Golang
+	// and iOS.
 
 	tlsCfg := &tls.Config{
 		Certificates:           []tls.Certificate{cert},
@@ -367,6 +368,14 @@ func pulseMain() {
 		SessionTicketsDisabled: true,
 		InsecureSkipVerify:     true,
 		MinVersion:             tls.VersionTLS12,
+		CipherSuites: []uint16{
+			tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+			tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+			tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+		},
 	}
 
 	// If the read or write rate should be limited, set up a rate limiter for it.