test: Correct the server and client certificates used in dialer_test.go

internal/cloudsql/instance_test.go

@@ -150,19 +150,6 @@ func TestConnectionInfoTLSConfig(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	// Now self sign the server's cert
-	// TODO: this also should return structured data and handle the PEM
-	// encoding elsewhere
-	certBytes, err := mock.SelfSign(i.Cert, i.Key)
-	if err != nil {
-		t.Fatal(err)
-	}
-	b, _ = pem.Decode(certBytes)
-	serverCACert, err := x509.ParseCertificate(b.Bytes)
-	if err != nil {
-		t.Fatal(err)
-	}
-
 	// Assemble a connection info with the raw and parsed client cert
 	// and the self-signed server certificate
 	ci := ConnectionInfo{
@@ -172,7 +159,7 @@ func TestConnectionInfoTLSConfig(t *testing.T) {
 			PrivateKey:  RSAKey,
 			Leaf:        clientCert,
 		},
-		ServerCACert: []*x509.Certificate{serverCACert},
+		ServerCACert: []*x509.Certificate{i.Cert},
 		DBVersion:    "doesn't matter here",
 		Expiration:   clientCert.NotAfter,
 	}
@@ -198,7 +185,7 @@ func TestConnectionInfoTLSConfig(t *testing.T) {
 	}
 
 	verifyPeerCert := got.VerifyPeerCertificate
-	err = verifyPeerCert([][]byte{serverCACert.Raw}, nil)
+	err = verifyPeerCert([][]byte{i.Cert.Raw}, nil)
 	if err != nil {
 		t.Fatalf("expected to verify peer cert, got error: %v", err)
 	}

internal/mock/certs.go

@@ -0,0 +1,310 @@
+// Copyright 2025 Google LLC
+
+// 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
+
+//     https://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 mock
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha1"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/binary"
+	"encoding/pem"
+	"math/big"
+	"time"
+)
+
+func name(cn string) pkix.Name {
+	return pkix.Name{
+		Country:      []string{"US"},
+		Organization: []string{"Google\\, Inc"},
+		CommonName:   cn,
+	}
+}
+
+// "C=US,O=Google\\, Inc,CN=Google Cloud SQL Root CA"
+var serverCaSubject = name("Google Cloud SQL Root CA")
+var intermediateCaSubject = name("Google Cloud SQL Intermediate CA")
+var signingCaSubject = name("Google Cloud SQL Signing CA foo:baz")
+var instanceWithCnSubject = name("myProject:myInstance")
+
+// TLSCertificates generates an accurate reproduction of the TLS certificates
+// used by Cloud SQL. This was translated to Go from the Java connector.
+//
+// From the cloud-sql-jdbc-socket-factory project:
+// core/src/test/java/com/google/cloud/sql/core/TestCertificateGenerator.java
+type TLSCertificates struct {
+	clientCertExpires time.Time
+	projectName       string
+	instanceName      string
+	sans              []string
+
+	serverCaKey             *rsa.PrivateKey
+	serverIntermediateCaKey *rsa.PrivateKey
+	clientSigningCaKey      *rsa.PrivateKey
+
+	serverCaCert               *x509.Certificate
+	serverIntermediateCaCert   *x509.Certificate
+	clientSigningCACertificate *x509.Certificate
+
+	serverKey            *rsa.PrivateKey
+	serverCert           *x509.Certificate
+	casServerCertificate *x509.Certificate
+}
+
+func mustGenerateKey() *rsa.PrivateKey {
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		panic(err)
+	}
+	return key
+}
+
+// newTLSCertificates creates a new instance of the TLSCertificates.
+func newTLSCertificates(projectName, instanceName string, sans []string, clientCertExpires time.Time) *TLSCertificates {
+	c := &TLSCertificates{
+		clientCertExpires: clientCertExpires,
+		projectName:       projectName,
+		instanceName:      instanceName,
+		sans:              sans,
+	}
+	c.rotateCA()
+	return c
+}
+
+// generateSKI Generate public key id. Certificates need to include
+// the key id to make the certificate chain work.
+func generateSKI(pub *rsa.PublicKey) []byte {
+	bs := make([]byte, 8)
+	binary.LittleEndian.PutUint64(bs, uint64(pub.E))
+
+	hasher := sha1.New()
+	hasher.Write(bs)
+	if pub.N != nil {
+		hasher.Write(pub.N.Bytes())
+	}
+	ski := hasher.Sum(nil)
+
+	return ski
+}
+
+// mustBuildRootCertificate produces a self-signed certificate.
+// or panics - use only for testing.
+func mustBuildRootCertificate(subject pkix.Name, k *rsa.PrivateKey) *x509.Certificate {
+
+	sn, err := rand.Int(rand.Reader, big.NewInt(1000))
+	if err != nil {
+		panic(err)
+	}
+
+	cert := &x509.Certificate{
+		SerialNumber:          sn,
+		SubjectKeyId:          generateSKI(&k.PublicKey),
+		Subject:               subject,
+		NotBefore:             time.Now(),
+		NotAfter:              time.Now().AddDate(1, 0, 0),
+		IsCA:                  true,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
+		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
+		BasicConstraintsValid: true,
+	}
+
+	certDerBytes, err := x509.CreateCertificate(rand.Reader, cert, cert, &k.PublicKey, k)
+	c, err := x509.ParseCertificate(certDerBytes)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}
+
+// mustBuildSignedCertificate produces a certificate for Subject that is signed
+// by the issuer.
+func mustBuildSignedCertificate(
+	isCa bool,
+	subject pkix.Name,
+	subjectPublicKey *rsa.PrivateKey,
+	certificateIssuer pkix.Name,
+	issuerPrivateKey *rsa.PrivateKey,
+	notAfter time.Time,
+	subjectAlternativeNames []string) *x509.Certificate {
+
+	sn, err := rand.Int(rand.Reader, big.NewInt(1000))
+	if err != nil {
+		panic(err)
+	}
+
+	cert := &x509.Certificate{
+		SerialNumber:          sn,
+		Subject:               subject,
+		SubjectKeyId:          generateSKI(&subjectPublicKey.PublicKey),
+		AuthorityKeyId:        generateSKI(&issuerPrivateKey.PublicKey),
+		Issuer:                certificateIssuer,
+		NotBefore:             time.Now(),
+		NotAfter:              notAfter,
+		IsCA:                  isCa,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
+		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
+		BasicConstraintsValid: true,
+		DNSNames:              subjectAlternativeNames,
+	}
+
+	certDerBytes, err := x509.CreateCertificate(rand.Reader, cert, cert, &subjectPublicKey.PublicKey, issuerPrivateKey)
+	c, err := x509.ParseCertificate(certDerBytes)
+	if err != nil {
+		panic(err)
+	}
+	return c
+
+}
+
+// toPEMFormat Converts an array of certificates to PEM format.
+func toPEMFormat(certs ...*x509.Certificate) ([]byte, error) {
+	certPEM := new(bytes.Buffer)
+
+	for _, cert := range certs {
+		err := pem.Encode(certPEM, &pem.Block{
+			Type:  "CERTIFICATE",
+			Bytes: cert.Raw,
+		})
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return certPEM.Bytes(), nil
+}
+
+// signWithClientKey produces a PEM encoded certificate client certificate
+// containing the clientKey public key, signed by the client CA certificate.
+func (ct *TLSCertificates) signWithClientKey(clientKey *rsa.PublicKey) ([]byte, error) {
+	notAfter := ct.clientCertExpires
+	if ct.clientCertExpires.IsZero() {
+		notAfter = time.Now().Add(1 * time.Hour)
+	}
+
+	// Create a signed cert from the client's public key.
+	cert := &x509.Certificate{ // TODO: Validate this format vs API
+		SerialNumber: &big.Int{},
+		Subject: pkix.Name{
+			Country:      []string{"US"},
+			Organization: []string{"Google, Inc"},
+			CommonName:   "Google Cloud SQL Client",
+		},
+		NotBefore:             time.Now(),
+		NotAfter:              notAfter,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
+		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
+		BasicConstraintsValid: true,
+	}
+	certBytes, err := x509.CreateCertificate(rand.Reader, cert, ct.clientSigningCACertificate, clientKey, ct.clientSigningCaKey)
+	if err != nil {
+		return nil, err
+	}
+	certPEM := new(bytes.Buffer)
+	err = pem.Encode(certPEM, &pem.Block{
+		Type:  "CERTIFICATE",
+		Bytes: certBytes,
+	})
+	if err != nil {
+		return nil, err
+	}
+	return certPEM.Bytes(), nil
+}
+
+// generateServerCertWithCn generates a server certificate for legacy
+// GOOGLE_MANAGED_INTERNAL_CA mode where the instance name is in the CN.
+func (ct *TLSCertificates) generateServerCertWithCn(cn string) *x509.Certificate {
+	return mustBuildSignedCertificate(
+		false,
+		name(cn),
+		ct.serverKey,
+		serverCaSubject,
+		ct.serverCaKey,
+		time.Now().Add(1*time.Hour), nil)
+}
+
+// serverChain creates a []tls.Certificate for use with a TLS server socket.
+// serverCAMode controls whether this returns a legacy or CAS server
+// certificate.
+func (ct *TLSCertificates) serverChain(serverCAMode string) []tls.Certificate {
+	// if this server is running in legacy mode
+	if serverCAMode == "" || serverCAMode == "GOOGLE_MANAGED_INTERNAL_CA" {
+		return []tls.Certificate{{
+			Certificate: [][]byte{ct.serverCert.Raw, ct.serverCaCert.Raw},
+			PrivateKey:  ct.serverKey,
+			Leaf:        ct.serverCert,
+		}}
+	}
+
+	return []tls.Certificate{{
+		Certificate: [][]byte{ct.casServerCertificate.Raw, ct.serverIntermediateCaCert.Raw, ct.serverCaCert.Raw},
+		PrivateKey:  ct.serverKey,
+		Leaf:        ct.casServerCertificate,
+	}}
+
+}
+func (ct *TLSCertificates) clientCAPool() *x509.CertPool {
+	clientCa := x509.NewCertPool()
+	clientCa.AddCert(ct.clientSigningCACertificate)
+	return clientCa
+}
+
+func (ct *TLSCertificates) rotateClientCA() {
+	ct.clientSigningCaKey = mustGenerateKey()
+	ct.clientSigningCACertificate = mustBuildRootCertificate(signingCaSubject, ct.clientSigningCaKey)
+}
+
+func (ct *TLSCertificates) rotateCA() {
+	oneYear := time.Now().AddDate(1, 0, 0)
+	ct.serverCaKey = mustGenerateKey()
+	ct.clientSigningCaKey = mustGenerateKey()
+	ct.serverKey = mustGenerateKey()
+	ct.serverIntermediateCaKey = mustGenerateKey()
+
+	ct.serverCaCert = mustBuildRootCertificate(serverCaSubject, ct.serverCaKey)
+
+	ct.serverIntermediateCaCert =
+		mustBuildSignedCertificate(
+			true,
+			intermediateCaSubject,
+			ct.serverIntermediateCaKey,
+			serverCaSubject,
+			ct.serverCaKey,
+			oneYear,
+			nil)
+
+	ct.casServerCertificate =
+		mustBuildSignedCertificate(
+			false,
+			name(""),
+			ct.serverKey,
+			intermediateCaSubject,
+			ct.serverIntermediateCaKey,
+			oneYear,
+			ct.sans)
+
+	ct.serverCert = mustBuildSignedCertificate(
+		false,
+		name(ct.projectName+":"+ct.instanceName),
+		ct.serverKey,
+		serverCaSubject,
+		ct.serverCaKey,
+		oneYear,
+		nil)
+
+	ct.rotateClientCA()
+}