Add working cert authority and tls proxy

.gitignore

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+tlself

LICENSE

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+MIT License
+
+Copyright (c) 2018 Chris Cherry
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# tlself
+
+Lightweight, dynamic, and easy local HTTPS web development
+
+## Requirements
+
+* OSX
+
+## How?
+
+First, tlself creates a self-signed certificate authority. This newly created CA is added to the list of trusted cert roots on the system. This means that if that CA is used to sign some other TLS cert, it will be trusted, and not result in a warning in your local web browsers.
+
+tlself then starts a TCP proxy that listens on localhost:443 and, using SNI, dynamically creates TLS certificates for incoming requests signed by the trusted self signed root. Each request is them proxied to localhost:80, which is where your local development server can be listening. This results in any local development domain you are using showing as HTTPS trusted in the browser.
+
+## Configuration
+
+Both the listening and backend TCP connections are configurable.
+
+* `LISTEN` - The IP address and port that the proxy should listen on to make TLS connections, default is 127.0.0.1:443
+* `BACKEND` - The IP address and port that the proxy should send incoming unencrypted connections to, default is 127.0.0.1:80

cert_authority.go

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+package main
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"fmt"
+	"io/ioutil"
+	"math/big"
+	"net"
+	"os"
+	"time"
+)
+
+type rootCA struct {
+	cert     *x509.Certificate
+	key      *ecdsa.PrivateKey
+	children map[string]*tls.Certificate
+}
+
+func (ca rootCA) GetCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
+	if tlsCert, ok := ca.children[hello.ServerName]; ok {
+		return tlsCert, nil
+	}
+	cert, priv := ca.Cert(hello.ServerName)
+	tlsCert := &tls.Certificate{
+		Certificate: [][]byte{cert.Raw},
+		PrivateKey:  priv,
+	}
+	ca.children[hello.ServerName] = tlsCert
+
+	return tlsCert, nil
+}
+
+func (ca rootCA) Cert(domain string) (*x509.Certificate, *ecdsa.PrivateKey) {
+	privKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "unable to generate ecdsa key: %v", err)
+		os.Exit(2)
+	}
+	publicKey := &privKey.PublicKey
+
+	commonSubject := dummySubject(domain)
+
+	cert := x509.Certificate{
+		SerialNumber:          randSerial(),
+		Subject:               commonSubject,
+		NotAfter:              time.Now().AddDate(20, 0, 0),
+		BasicConstraintsValid: true,
+		IsCA:        false,
+		KeyUsage:    x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		DNSNames:    []string{domain},
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &cert, ca.cert, publicKey, ca.key)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to create certificate: %v", err)
+		os.Exit(2)
+	}
+
+	finalCert, err := x509.ParseCertificate(derBytes)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to parse created certificate: %v", err)
+		os.Exit(2)
+	}
+
+	return finalCert, privKey
+}
+
+func LoadOrCreateRootCA(certFile, keyFile string) rootCA {
+
+	certExists := false
+	keyExists := false
+
+	if _, err := os.Stat(certFile); err == nil {
+		certExists = true
+	}
+
+	if _, err := os.Stat(keyFile); err == nil {
+		keyExists = true
+	}
+
+	if certExists && keyExists {
+		return loadCA(certFile, keyFile)
+	}
+
+	// Clean up either file if it exists
+	_ = os.Remove(certFile)
+	_ = os.Remove(keyFile)
+
+	return createCA(certFile, keyFile)
+}
+
+func loadCA(certFile string, keyFile string) rootCA {
+
+	certBytes, err := ioutil.ReadFile(certFile)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error reading root cert file: %v", err)
+		os.Exit(2)
+	}
+
+	certBlock, _ := pem.Decode(certBytes)
+	if certBlock == nil {
+		fmt.Fprintf(os.Stderr, "Error decoding PEM of root cert file: %v", err)
+		os.Exit(2)
+	}
+
+	cert, err := x509.ParseCertificate(certBlock.Bytes)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error parsing root cert file: %v", err)
+		os.Exit(2)
+	}
+
+	keyBytes, err := ioutil.ReadFile(keyFile)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error reading root private key file: %v", err)
+		os.Exit(2)
+	}
+
+	keyBlock, _ := pem.Decode(keyBytes)
+	if keyBlock == nil {
+		fmt.Fprintf(os.Stderr, "Error decoding PEM of root private key file: %v", err)
+		os.Exit(2)
+	}
+
+	key, err := x509.ParseECPrivateKey(keyBlock.Bytes)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error parsing root private key file: %v", err)
+		os.Exit(2)
+	}
+
+	return rootCA{
+		cert:     cert,
+		children: make(map[string]*tls.Certificate, 10),
+		key:      key,
+	}
+}
+
+func createCA(certFile string, keyFile string) rootCA {
+	privKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Unable to generate ecdsa key for root cert: %v", err)
+		os.Exit(2)
+	}
+	publicKey := &privKey.PublicKey
+
+	commonSubject := dummySubject("tlself.root")
+
+	cert := x509.Certificate{
+		SerialNumber:          randSerial(),
+		Subject:               commonSubject,
+		NotAfter:              time.Now().AddDate(20, 0, 0),
+		MaxPathLen:            0,
+		MaxPathLenZero:        true,
+		BasicConstraintsValid: true,
+		IsCA:        true,
+		KeyUsage:    x509.KeyUsageCertSign | x509.KeyUsageCRLSign | x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		IPAddresses: []net.IP{net.ParseIP("127.0.0.1")},
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &cert, &cert, publicKey, privKey)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to create root certificate: %v", err)
+		os.Exit(2)
+	}
+
+	finalCert, err := x509.ParseCertificate(derBytes)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to parse created root certificate: %v", err)
+		os.Exit(2)
+	}
+
+	certOut, err := os.Create(certFile)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to open cert.pem for writing root cert: %v", err)
+		os.Exit(2)
+	}
+
+	err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error encoding root cert to pem block: %v", err)
+		os.Exit(2)
+	}
+
+	err = certOut.Close()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error closing root cert file: %v", err)
+		os.Exit(2)
+	}
+
+	keyOut, err := os.OpenFile(keyFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to open key.pem for writing root key: %v", err)
+		os.Exit(2)
+	}
+
+	err = pem.Encode(keyOut, pemBlockForKey(privKey))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error encoding root private key to pem block: %v", err)
+		os.Exit(2)
+	}
+
+	err = keyOut.Close()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error closing root private key file: %v", err)
+		os.Exit(2)
+	}
+
+	return rootCA{
+		cert:     finalCert,
+		children: make(map[string]*tls.Certificate, 10),
+		key:      privKey,
+	}
+}
+
+func pemBlockForKey(priv *ecdsa.PrivateKey) *pem.Block {
+	b, err := x509.MarshalECPrivateKey(priv)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "unable to marshal ECDSA private key: %v", err)
+		os.Exit(2)
+	}
+	return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
+}
+
+func dummySubject(common string) pkix.Name {
+	return pkix.Name{
+		CommonName:         common,
+		Organization:       []string{"No Corp"},
+		OrganizationalUnit: []string{"WWW"},
+		Locality:           []string{"YYY"},
+		Country:            []string{"QQQ"},
+		Province:           []string{"ZZZ"},
+	}
+}
+
+func randSerial() *big.Int {
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to generate serial number: %s", err)
+		os.Exit(2)
+	}
+	return serialNumber
+}