crypto/tls: add SessionState.Extra

[gostls13.git] / src / crypto / tls / ticket.go

diff --git a/src/crypto/tls/ticket.go b/src/crypto/tls/ticket.go
index 2ea65a6b41272a785b71d0151f72add136ef45c0..24f6206fe114e20c131db60a643205976ca55489 100644 (file)
--- a/src/crypto/tls/ticket.go
+++ b/src/crypto/tls/ticket.go
@@ -33,6 +33,7 @@ type SessionState struct {
        //       uint16 cipher_suite;
        //       uint64 created_at;
        //       opaque secret<1..2^8-1>;
+       //       opaque extra<0..2^24-1>;
        //       CertificateEntry certificate_list<0..2^24-1>;
        //       select (SessionState.type) {
        //           case server: /* empty */;
@@ -50,6 +51,18 @@ type SessionState struct {
        //   } SessionState;
        //
 
+       // Extra is ignored by crypto/tls, but is encoded by [SessionState.Bytes]
+       // and parsed by [ParseSessionState].
+       //
+       // This allows [Config.UnwrapSession]/[Config.WrapSession] and
+       // [ClientSessionCache] implementations to store and retrieve additional
+       // data.
+       //
+       // If Extra is already set, the implementation must preserve the previous
+       // value across a round-trip, for example by appending and stripping a
+       // fixed-length suffix.
+       Extra []byte
+
        version     uint16
        isClient    bool
        cipherSuite uint16
@@ -90,6 +103,9 @@ func (s *SessionState) Bytes() ([]byte, error) {
        b.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
                b.AddBytes(s.secret)
        })
+       b.AddUint24LengthPrefixed(func(b *cryptobyte.Builder) {
+               b.AddBytes(s.Extra)
+       })
        marshalCertificate(&b, s.certificate())
        if s.isClient {
                b.AddUint24LengthPrefixed(func(b *cryptobyte.Builder) {
@@ -144,6 +160,7 @@ func ParseSessionState(data []byte) (*SessionState, error) {
                !s.ReadUint16(&ss.cipherSuite) ||
                !readUint64(&s, &ss.createdAt) ||
                !readUint8LengthPrefixed(&s, &ss.secret) ||
+               !readUint24LengthPrefixed(&s, &ss.Extra) ||
                len(ss.secret) == 0 ||
                !unmarshalCertificate(&s, &cert) {
                return nil, errors.New("tls: invalid session encoding")