From b3c28ef2ea863c52db8ba2c65eeb88e470abb108 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Thu, 3 Sep 2020 10:52:52 +0700
Subject: [PATCH] generate a self-signed certificate for the handshake fuzzer

---
 fuzzing/handshake/fuzz.go         | 28 +++++++++++++++++++-----
 fuzzing/internal/helper/helper.go | 36 +++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/fuzzing/handshake/fuzz.go b/fuzzing/handshake/fuzz.go
index 6ca208744..71d814218 100644
--- a/fuzzing/handshake/fuzz.go
+++ b/fuzzing/handshake/fuzz.go
@@ -1,17 +1,34 @@
 package handshake
 
 import (
+	"crypto/rand"
+	"crypto/rsa"
 	"crypto/tls"
+	"crypto/x509"
 	"fmt"
+	"log"
 
 	"github.com/lucas-clemente/quic-go/fuzzing/internal/helper"
 	"github.com/lucas-clemente/quic-go/internal/handshake"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
-	"github.com/lucas-clemente/quic-go/internal/testdata"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/lucas-clemente/quic-go/internal/wire"
 )
 
+var cert *tls.Certificate
+var certPool *x509.CertPool
+
+func init() {
+	priv, err := rsa.GenerateKey(rand.Reader, 1024)
+	if err != nil {
+		log.Fatal(err)
+	}
+	cert, certPool, err = helper.GenerateCertificate(priv)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
 type messageType uint8
 
 // TLS handshake message types.
@@ -137,7 +154,7 @@ func Fuzz(data []byte) int {
 	clientConf := &tls.Config{
 		ServerName: "localhost",
 		NextProtos: []string{alpn},
-		RootCAs:    testdata.GetRootCA(),
+		RootCAs:    certPool,
 	}
 	if useSessionTicketCache {
 		clientConf.ClientSessionCache = tls.NewLRUClientSessionCache(5)
@@ -161,8 +178,6 @@ func Fuzz(data []byte) int {
 	)
 
 	sChunkChan, sInitialStream, sHandshakeStream := initStreams()
-	config := testdata.GetTLSConfig()
-	config.NextProtos = []string{alpn}
 	serverRunner := newRunner(&client, &server, "server")
 	server = handshake.NewCryptoSetupServer(
 		sInitialStream,
@@ -172,7 +187,10 @@ func Fuzz(data []byte) int {
 		nil,
 		&wire.TransportParameters{},
 		serverRunner,
-		config,
+		&tls.Config{
+			Certificates: []tls.Certificate{*cert},
+			NextProtos:   []string{alpn},
+		},
 		enable0RTTServer,
 		utils.NewRTTStats(),
 		nil,
diff --git a/fuzzing/internal/helper/helper.go b/fuzzing/internal/helper/helper.go
index 1513c3fa0..b4a4ed328 100644
--- a/fuzzing/internal/helper/helper.go
+++ b/fuzzing/internal/helper/helper.go
@@ -1,11 +1,18 @@
 package helper
 
 import (
+	"crypto"
+	"crypto/rand"
 	"crypto/sha1"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
 	"encoding/hex"
 	"io/ioutil"
+	"math/big"
 	"os"
 	"path/filepath"
+	"time"
 )
 
 // NthBit gets the n-th bit of a byte (counting starts at 0).
@@ -35,3 +42,32 @@ func WriteCorpusFile(path string, data []byte) error {
 func WriteCorpusFileWithPrefix(path string, data []byte, n int) error {
 	return WriteCorpusFile(path, append(make([]byte, n), data...))
 }
+
+// GenerateCertificate generates a self-signed certificate.
+// It returns the certificate and a x509.CertPool containing that certificate.
+func GenerateCertificate(priv crypto.Signer) (*tls.Certificate, *x509.CertPool, error) {
+	template := x509.Certificate{
+		SerialNumber:          big.NewInt(1),
+		Subject:               pkix.Name{Organization: []string{"quic-go fuzzer"}},
+		NotBefore:             time.Now().Add(-24 * time.Hour),
+		NotAfter:              time.Now().Add(30 * 24 * time.Hour),
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		DNSNames:              []string{"localhost"},
+		BasicConstraintsValid: true,
+	}
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, priv.Public(), priv)
+	if err != nil {
+		return nil, nil, err
+	}
+	cert, err := x509.ParseCertificate(derBytes)
+	if err != nil {
+		return nil, nil, err
+	}
+	certPool := x509.NewCertPool()
+	certPool.AddCert(cert)
+	return &tls.Certificate{
+		Certificate: [][]byte{derBytes},
+		PrivateKey:  priv,
+	}, certPool, nil
+}