support save certificate file

main.go

@@ -1,10 +1,17 @@
 package main
 
 import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"os"
+	"path"
 	"time"
 
 	"github.com/faceair/betproxy"
@@ -13,9 +20,10 @@ import (
 )
 
 func main() {
-	var host, gopath string
+	var host, capath, gopath string
 	var port int
-	flag.StringVar(&gopath, "gopath", os.Getenv("GOPATH"), "path to the git repository")
+	flag.StringVar(&capath, "capath", os.TempDir(), "path to save gotit certificate")
+	flag.StringVar(&gopath, "gopath", os.Getenv("GOPATH"), "path to save git repository")
 	flag.StringVar(&host, "host", "0.0.0.0", "proxy server host")
 	flag.IntVar(&port, "port", 0, "proxy server port")
 	flag.Parse()
@@ -25,7 +33,15 @@ func main() {
 		os.Exit(0)
 	}
 
-	tlsCfg, err := generateTLSCfg()
+	cacert, cakey, err := loadCA(capath)
+	if err != nil {
+		panic(err)
+	}
+	tlsCfg, err := mitm.NewConfig(cacert, cakey)
+	if err != nil {
+		panic(err)
+	}
+
 	if err != nil {
 		panic(err)
 	}
@@ -38,10 +54,78 @@ func main() {
 	log.Fatal(service.Listen())
 }
 
-func generateTLSCfg() (*mitm.Config, error) {
-	cacert, cakey, err := mitm.NewAuthority("betproxy", "betproxy", 10*365*24*time.Hour)
+func loadCA(capath string) (*x509.Certificate, *rsa.PrivateKey, error) {
+	certpath := path.Join(capath, "gotit.cert.pem")
+	keypath := path.Join(capath, "gotit.key.pem")
+
+	if _, err := os.Stat(certpath); os.IsNotExist(err) {
+		err := generateCA(capath, certpath, keypath)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+
+	cert, err := ioutil.ReadFile(certpath)
+	if err != nil {
+		return nil, nil, err
+	}
+	key, err := ioutil.ReadFile(keypath)
+	if err != nil {
+		return nil, nil, err
+	}
+	certBlock, _ := pem.Decode(cert)
+	if certBlock == nil {
+		return nil, nil, errors.New("Failed to decode ca certificate")
+	}
+	keyBlock, _ := pem.Decode(key)
+	if keyBlock == nil {
+		return nil, nil, errors.New("Failed to decode ca private key")
+	}
+	rawKey, err := x509.ParsePKCS1PrivateKey(keyBlock.Bytes)
+	if err != nil {
+		return nil, nil, err
+	}
+	rawCert, err := x509.ParseCertificate(certBlock.Bytes)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return rawCert, rawKey, nil
+}
+
+func generateCA(capath, certpath, keypath string) error {
+	err := os.MkdirAll(capath, os.ModePerm)
+	if err != nil {
+		return err
+	}
+
+	cacert, cakey, err := mitm.NewAuthority("gotit", "faceair", 10*365*24*time.Hour)
+	if err != nil {
+		return err
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, cacert, cacert, &cakey.PublicKey, cakey)
 	if err != nil {
-		return nil, err
+		return err
 	}
-	return mitm.NewConfig(cacert, cakey)
+	certOut, err := os.Create(certpath)
+	if err != nil {
+		return err
+	}
+	if err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
+		return err
+	}
+	if err = certOut.Close(); err != nil {
+		return err
+	}
+
+	keyOut, err := os.OpenFile(keypath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	if err != nil {
+		return err
+	}
+	if err = pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(cakey)}); err != nil {
+		return err
+	}
+
+	return keyOut.Close()
 }