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| author | Nikos Mavrogiannopoulos <nmav@redhat.com> | 2018-05-10 14:25:12 +0200 |
|---|---|---|
| committer | Nikos Mavrogiannopoulos <nmav@gnutls.org> | 2018-05-26 04:12:03 +0000 |
| commit | aed3ac3a2dd976bbdef4705d7caa3db2b9239c79 (patch) | |
| tree | 566ec9fbd056f5f0c762800ff15abecaf369f0a5 | |
| parent | b31203552840cc7f3a66a18780bb785d0d6e963c (diff) | |
| download | gnutls-aed3ac3a2dd976bbdef4705d7caa3db2b9239c79.tar.gz | |
psk_ke_modes: introduce psk_ke_modes_is_required() and update doc
This adds a helper function to be extended when session resumption
is added, and clarifies why we send a prioritized list on ke modes.
Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>
Signed-off-by: Ander Juaristi <a@juaristi.eus>
| -rw-r--r-- | lib/ext/psk_ke_modes.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/lib/ext/psk_ke_modes.c b/lib/ext/psk_ke_modes.c index af136fd3ca..0da358fcd7 100644 --- a/lib/ext/psk_ke_modes.c +++ b/lib/ext/psk_ke_modes.c @@ -28,6 +28,21 @@ #define PSK_KE 0 #define PSK_DHE_KE 1 +static bool +psk_ke_modes_is_required(gnutls_session_t session) +{ + gnutls_psk_client_credentials_t cred; + + if (session->internals.priorities->have_psk) { + cred = (gnutls_psk_client_credentials_t) + _gnutls_get_cred(session, GNUTLS_CRD_PSK); + if (cred && _gnutls_have_psk_credentials(cred)) + return 1; + } + + return 0; +} + /* * We only support ECDHE-authenticated PSKs. * The client just sends a "psk_key_exchange_modes" extension @@ -38,7 +53,6 @@ psk_ke_modes_send_params(gnutls_session_t session, gnutls_buffer_t extdata) { int ret; - gnutls_psk_client_credentials_t cred; const version_entry_st *vers; uint8_t data[2]; unsigned pos, i; @@ -46,19 +60,21 @@ psk_ke_modes_send_params(gnutls_session_t session, unsigned have_psk = 0; /* Server doesn't send psk_key_exchange_modes */ - if (session->security_parameters.entity == GNUTLS_SERVER || - !session->internals.priorities->have_psk) + if (session->security_parameters.entity == GNUTLS_SERVER) return 0; - cred = (gnutls_psk_client_credentials_t) - _gnutls_get_cred(session, GNUTLS_CRD_PSK); - if (cred == NULL || _gnutls_have_psk_credentials(cred) == 0) + if (!psk_ke_modes_is_required(session)) return 0; vers = _gnutls_version_max(session); if (!vers || !vers->tls13_sem) return 0; + /* We send the list prioritized according to our preferences as a convention + * (used throughout the protocol), even if the protocol doesn't mandate that + * for this particular message. That way we can keep the TLS 1.2 semantics/ + * prioritization when negotiating PSK or DHE-PSK. Receiving servers would + * very likely respect our prioritization if they parse the message serially. */ pos = 0; for (i=0;i<session->internals.priorities->_kx.algorithms;i++) { if (session->internals.priorities->_kx.priority[i] == GNUTLS_KX_PSK && !have_psk) { |