Fix session ticket and SNI

When session tickets are used, it's possible that SNI might swtich the
SSL_CTX on an SSL. Normally, this is not a problem, because the
initial_ctx/session_ctx are used for all session ticket/id processes.

However, when the SNI callback occurs, it's possible that the callback
may update the options in the SSL from the SSL_CTX, and this could
cause SSL_OP_NO_TICKET to be set. If this occurs, then two bad things
can happen:

1. The session ticket TLSEXT may not be written when the ticket expected
flag is set. The state machine transistions to writing the ticket, and
the client responds with an error as its not expecting a ticket.
2. When creating the session ticket, if the ticket key cb returns 0
the crypto/hmac contexts are not initialized, and the code crashes when
trying to encrypt the session ticket.

To fix 1, if the ticket TLSEXT is not written out, clear the expected
ticket flag.
To fix 2, consider a return of 0 from the ticket key cb a recoverable
error, and write a 0 length ticket and continue. The client-side code
can explicitly handle this case.

Fix these two cases, and add unit test code to validate ticket behavior.

Reviewed-by: Emilia Käsper <emilia@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1098)

1 files changed, 17 insertions, 0 deletions

diff --git a/test/ssl_test_ctx.h b/test/ssl_test_ctx.h
index fe928075c6..e7570856b1 100644
--- a/test/ssl_test_ctx.h
+++ b/test/ssl_test_ctx.h
@@ -26,6 +26,18 @@ typedef enum {
     SSL_TEST_VERIFY_REJECT_ALL
 } ssl_verify_callback_t;
 
+typedef enum {
+    SSL_TEST_SERVERNAME_SERVER1 = 0, /* Default */
+    SSL_TEST_SERVERNAME_SERVER2
+} ssl_servername_t;
+
+typedef enum {
+    SSL_TEST_SESSION_TICKET_IGNORE = 0, /* Default */
+    SSL_TEST_SESSION_TICKET_YES,
+    SSL_TEST_SESSION_TICKET_NO,
+    SSL_TEST_SESSION_TICKET_BROKEN, /* Special test */
+} ssl_session_ticket_expected_t;
+
 typedef struct ssl_test_ctx {
     /* Test expectations. */
     /* Defaults to SUCCESS. */
@@ -41,12 +53,17 @@ typedef struct ssl_test_ctx {
     int protocol;
     /* One of a number of predefined custom callbacks. */
     ssl_verify_callback_t client_verify_callback;
+    /* One of a number of predefined server names use by the client */
+    ssl_servername_t servername;
+    ssl_session_ticket_expected_t session_ticket_expected;
 } SSL_TEST_CTX;
 
 const char *ssl_test_result_name(ssl_test_result_t result);
 const char *ssl_alert_name(int alert);
 const char *ssl_protocol_name(int protocol);
 const char *ssl_verify_callback_name(ssl_verify_callback_t verify_callback);
+const char *ssl_servername_name(ssl_servername_t server);
+const char *ssl_session_ticket_expected_name(ssl_session_ticket_expected_t server);
 
 /*
  * Load the test case context from |conf|.