fix conversion of qtls.ClientHelloInfo in GetCertificate

internal/handshake/qtls.go

@@ -62,11 +62,7 @@ func tlsConfigToQtlsConfig(
 	var getConfigForClient func(ch *qtls.ClientHelloInfo) (*qtls.Config, error)
 	if c.GetConfigForClient != nil {
 		getConfigForClient = func(ch *qtls.ClientHelloInfo) (*qtls.Config, error) {
-			var chi *tls.ClientHelloInfo
-			if ch != nil {
-				chi = toTLSClientHelloInfo(ch)
-			}
-			tlsConf, err := c.GetConfigForClient(chi)
+			tlsConf, err := c.GetConfigForClient(toTLSClientHelloInfo(ch))
 			if err != nil {
 				return nil, err
 			}
@@ -76,6 +72,19 @@ func tlsConfigToQtlsConfig(
 			return tlsConfigToQtlsConfig(tlsConf, recordLayer, extHandler, rttStats, getDataForSessionState, setDataFromSessionState, accept0RTT, rejected0RTT, enable0RTT), nil
 		}
 	}
+	var getCertificate func(ch *qtls.ClientHelloInfo) (*qtls.Certificate, error)
+	if c.GetCertificate != nil {
+		getCertificate = func(ch *qtls.ClientHelloInfo) (*qtls.Certificate, error) {
+			cert, err := c.GetCertificate(toTLSClientHelloInfo(ch))
+			if err != nil {
+				return nil, err
+			}
+			if cert == nil {
+				return nil, nil
+			}
+			return (*qtls.Certificate)(unsafe.Pointer(cert)), nil
+		}
+	}
 	var csc qtls.ClientSessionCache
 	if c.ClientSessionCache != nil {
 		csc = newClientSessionCache(c.ClientSessionCache, rttStats, getDataForSessionState, setDataFromSessionState)
@@ -87,7 +96,7 @@ func tlsConfigToQtlsConfig(
 		// NameToCertificate is deprecated, but we still need to copy it if the user sets it.
 		//nolint:staticcheck
 		NameToCertificate:           *(*map[string]*qtls.Certificate)(unsafe.Pointer(&c.NameToCertificate)),
-		GetCertificate:              *(*func(*qtls.ClientHelloInfo) (*qtls.Certificate, error))(unsafe.Pointer(&c.GetCertificate)),
+		GetCertificate:              getCertificate,
 		GetClientCertificate:        *(*func(*qtls.CertificateRequestInfo) (*qtls.Certificate, error))(unsafe.Pointer(&c.GetClientCertificate)),
 		GetConfigForClient:          getConfigForClient,
 		VerifyPeerCertificate:       c.VerifyPeerCertificate,

internal/handshake/qtls_test.go

@@ -132,6 +132,47 @@ var _ = Describe("qtls.Config generation", func() {
 		})
 	})
 
+	Context("GetCertificate callback", func() {
+		It("returns a certificate", func() {
+			tlsConf := &tls.Config{
+				GetCertificate: func(*tls.ClientHelloInfo) (*tls.Certificate, error) {
+					return &tls.Certificate{Certificate: [][]byte{[]byte("foo"), []byte("bar")}}, nil
+				},
+			}
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsCert, err := qtlsConf.GetCertificate(nil)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(qtlsCert).ToNot(BeNil())
+			Expect(qtlsCert.Certificate).To(Equal([][]byte{[]byte("foo"), []byte("bar")}))
+		})
+
+		It("doesn't set it if absent", func() {
+			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			Expect(qtlsConf.GetCertificate).To(BeNil())
+		})
+
+		It("returns errors", func() {
+			tlsConf := &tls.Config{
+				GetCertificate: func(*tls.ClientHelloInfo) (*tls.Certificate, error) {
+					return nil, errors.New("test")
+				},
+			}
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			_, err := qtlsConf.GetCertificate(nil)
+			Expect(err).To(MatchError("test"))
+		})
+
+		It("returns nil when the callback returns nil", func() {
+			tlsConf := &tls.Config{
+				GetCertificate: func(*tls.ClientHelloInfo) (*tls.Certificate, error) {
+					return nil, nil
+				},
+			}
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			Expect(qtlsConf.GetCertificate(nil)).To(BeNil())
+		})
+	})
+
 	Context("ClientSessionCache", func() {
 		It("doesn't set if absent", func() {
 			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)

internal/handshake/unsafe.go

@@ -81,6 +81,9 @@ type qtlsClientHelloInfo struct {
 }
 
 func toTLSClientHelloInfo(chi *qtls.ClientHelloInfo) *tls.ClientHelloInfo {
+	if chi == nil {
+		return nil
+	}
 	qtlsCHI := (*qtlsClientHelloInfo)(unsafe.Pointer(chi))
 	var config *tls.Config
 	if qtlsCHI.config != nil {