Initalize TLS.Config when connecting to Redis with TLS (#1296)

* init TLS.Config when connecting to Redis with TLS

* don't overwrite TLS config if it exists

* add tests for Redis with TLS

* remove hardcoded certs

* add GenerateCert func

* use GenerateCert util func

* fix issue reported by go fmt

* limit return statements in GenerateCert

pkg/util/util.go

@@ -1,9 +1,15 @@
 package util
 
 import (
+	"crypto/rand"
+	"crypto/rsa"
 	"crypto/x509"
+	"crypto/x509/pkix"
 	"fmt"
 	"io/ioutil"
+	"math/big"
+	"net"
+	"time"
 )
 
 func GetCertPool(paths []string) (*x509.CertPool, error) {
@@ -23,3 +29,40 @@ func GetCertPool(paths []string) (*x509.CertPool, error) {
 	}
 	return pool, nil
 }
+
+// https://golang.org/src/crypto/tls/generate_cert.go as a function
+func GenerateCert() ([]byte, []byte, error) {
+	var err error
+
+	priv, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	keyBytes, err := x509.MarshalPKCS8PrivateKey(priv)
+	if err != nil {
+		return nil, keyBytes, err
+	}
+
+	serialNumber, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	if err != nil {
+		return nil, keyBytes, err
+	}
+
+	notBefore := time.Now()
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{"OAuth2 Proxy Test Suite"},
+		},
+		NotBefore: notBefore,
+		NotAfter:  notBefore.Add(time.Hour),
+		KeyUsage:  x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
+
+		ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+
+		IPAddresses: []net.IP{net.ParseIP("127.0.0.1")},
+	}
+	certBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
+	return certBytes, keyBytes, err
+}