mkcerts: Clean up and rename to be nicer

mkcerts/certs.go

@@ -17,8 +17,8 @@ import (
 	"time"
 )
 
-// CreateCert creates a testing ECDSA certificate, outputting the cert and key at the given filenames.
-func CreateCert(orgName string, host string, certFilename string, keyFilename string) error {
+// CreateCertBytes creates a testing ECDSA certificate, returning the cert and key bytes.
+func CreateCertBytes(orgName string, host string) (certBytes []byte, keyBytes []byte, err error) {
 	validFrom := time.Now()
 	validFor := 365 * 24 * time.Hour
 	notAfter := validFrom.Add(validFor)
@@ -28,7 +28,7 @@ func CreateCert(orgName string, host string, certFilename string, keyFilename st
 	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
 	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
 	if err != nil {
-		return fmt.Errorf("failed to generate serial number: %s", err)
+		return nil, nil, fmt.Errorf("failed to generate serial number: %s", err)
 	}
 
 	template := x509.Certificate{
@@ -54,26 +54,47 @@ func CreateCert(orgName string, host string, certFilename string, keyFilename st
 
 	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
 	if err != nil {
-		return fmt.Errorf("Failed to create certificate: %s", err.Error())
+		return nil, nil, fmt.Errorf("Failed to create certificate: %s", err.Error())
+	}
+
+	certBytes = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
+
+	b, err := x509.MarshalECPrivateKey(priv)
+	if err != nil {
+		return nil, nil, fmt.Errorf("Unable to marshal ECDSA private key: %v", err.Error())
+	}
+	pemBlock := pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
+	keyBytes = pem.EncodeToMemory(&pemBlock)
+	return certBytes, keyBytes, nil
+}
+
+// CreateCert creates a testing ECDSA certificate, outputting the cert and key at the given filenames.
+func CreateCert(orgName string, host string, certFilename string, keyFilename string) error {
+	certBytes, keyBytes, err := CreateCertBytes(orgName, host)
+
+	if err != nil {
+		return err
 	}
 
 	certOut, err := os.Create(certFilename)
 	if err != nil {
 		return fmt.Errorf("failed to open %s for writing: %s", certFilename, err.Error())
 	}
-	pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
-	certOut.Close()
+	defer certOut.Close()
+	_, err = certOut.Write(certBytes)
+	if err != nil {
+		return fmt.Errorf("failed to write out cert file %s: %s", certFilename, err.Error())
+	}
 
 	keyOut, err := os.OpenFile(keyFilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 	if err != nil {
 		return fmt.Errorf("failed to open %s for writing: %s", keyFilename, err.Error())
 	}
-	b, err := x509.MarshalECPrivateKey(priv)
+	defer keyOut.Close()
+	_, err = keyOut.Write(keyBytes)
 	if err != nil {
-		return fmt.Errorf("Unable to marshal ECDSA private key: %v", err.Error())
+		return fmt.Errorf("failed to write out key file %s: %s", keyFilename, err.Error())
 	}
-	pemBlock := pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
-	pem.Encode(keyOut, &pemBlock)
-	keyOut.Close()
+
 	return nil
 }