Automatically serve API on https with self-signed cert

pkg/util/crypto.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"fmt"
+	"io/ioutil"
+	"math/big"
+	"net"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// GenerateSelfSignedCert creates a self-signed certificate and key for the given host.
+// Host may be an IP or a DNS name
+// The certificate will be created with file mode 0644. The key will be created with file mode 0600.
+// If the certificate or key files already exist, they will be overwritten.
+// Any parent directories of the certPath or keyPath will be created as needed with file mode 0755.
+func GenerateSelfSignedCert(host, certPath, keyPath string) error {
+	priv, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		return err
+	}
+
+	template := x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		Subject: pkix.Name{
+			CommonName: fmt.Sprintf("%s@%d", host, time.Now().Unix()),
+		},
+		NotBefore: time.Now(),
+		NotAfter:  time.Now().Add(time.Hour * 24 * 365),
+
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+	}
+
+	if ip := net.ParseIP(host); ip != nil {
+		template.IPAddresses = append(template.IPAddresses, ip)
+	} else {
+		template.DNSNames = append(template.DNSNames, host)
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
+	if err != nil {
+		return err
+	}
+
+	// Generate cert
+	certBuffer := bytes.Buffer{}
+	if err := pem.Encode(&certBuffer, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
+		return err
+	}
+
+	// Generate key
+	keyBuffer := bytes.Buffer{}
+	if err := pem.Encode(&keyBuffer, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)}); err != nil {
+		return err
+	}
+
+	// Write cert
+	if err := os.MkdirAll(filepath.Dir(certPath), os.FileMode(0755)); err != nil {
+		return err
+	}
+	if err := ioutil.WriteFile(certPath, certBuffer.Bytes(), os.FileMode(0644)); err != nil {
+		return err
+	}
+
+	// Write key
+	if err := os.MkdirAll(filepath.Dir(keyPath), os.FileMode(0755)); err != nil {
+		return err
+	}
+	if err := ioutil.WriteFile(keyPath, keyBuffer.Bytes(), os.FileMode(0600)); err != nil {
+		return err
+	}
+
+	return nil
+}