Add session ticket support for server

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 02a4760..c139fb5 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -397,6 +397,7 @@
     return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
 }
 
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
 MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_select_ciphersuite_for_resumption(
                mbedtls_ssl_context *ssl,
@@ -406,15 +407,51 @@
                uint16_t *selected_ciphersuite,
                const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info )
 {
-    ((void) ssl);
-    ((void) session);
-    ((void) cipher_suites);
-    ((void) cipher_suites_end);
+
     *selected_ciphersuite = 0;
     *selected_ciphersuite_info = NULL;
-    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+    for( const unsigned char *p = cipher_suites; p < cipher_suites_end; p += 2 )
+    {
+        uint16_t cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 );
+        const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
+
+        if( cipher_suite != session->ciphersuite )
+            continue;
+
+        ciphersuite_info = ssl_tls13_validate_peer_ciphersuite( ssl,
+                                                                cipher_suite );
+        if( ciphersuite_info == NULL )
+            continue;
+
+        *selected_ciphersuite = session->ciphersuite;
+        *selected_ciphersuite_info = ciphersuite_info;
+
+        return( 0 );
+
+    }
+
+    return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_session_copy( mbedtls_ssl_session *dst,
+                                   mbedtls_ssl_session *src )
+{
+    dst->endpoint = src->endpoint;
+    dst->ciphersuite = src->ciphersuite;
+    dst->ticket_age_add = src->ticket_age_add;
+    dst->ticket_flags = src->ticket_flags;
+    dst->resumption_key_len = src->resumption_key_len;
+    if( src->resumption_key_len == 0 )
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    memcpy( dst->resumption_key, src->resumption_key, src->resumption_key_len );
+#if defined(MBEDTLS_HAVE_TIME)
+    dst->start = src->start;
+#endif
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
 /* Parser for pre_shared_key extension in client hello
  *    struct {
  *        opaque identity<1..2^16-1>;
@@ -484,17 +521,23 @@
     {
         const unsigned char *identity;
         size_t identity_len;
+        uint32_t obfuscated_ticket_age;
         const unsigned char *binder;
         size_t binder_len;
         int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
         int psk_type;
         uint16_t cipher_suite;
         const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+        mbedtls_ssl_session session;
+        memset( &session, 0, sizeof( session ) );
+#endif
 
         MBEDTLS_SSL_CHK_BUF_READ_PTR( p_identity_len, identities_end, 2 + 1 + 4 );
         identity_len = MBEDTLS_GET_UINT16_BE( p_identity_len, 0 );
         identity = p_identity_len + 2;
         MBEDTLS_SSL_CHK_BUF_READ_PTR( identity, identities_end, identity_len + 4 );
+        obfuscated_ticket_age = MBEDTLS_GET_UINT32_BE( identity , identity_len );
         p_identity_len += identity_len + 6;
 
         MBEDTLS_SSL_CHK_BUF_READ_PTR( p_binder_len, binders_end, 1 + 32 );
@@ -508,7 +551,8 @@
             continue;
 
         ret = ssl_tls13_offered_psks_check_identity_match(
-                                    ssl, identity, identity_len, &psk_type );
+                  ssl, identity, identity_len, obfuscated_ticket_age,
+                  &session, &psk_type );
         if( ret != SSL_TLS1_3_OFFERED_PSK_MATCH )
             continue;
 
@@ -521,9 +565,13 @@
                             &cipher_suite, &ciphersuite_info );
                 break;
             case MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION:
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
                 ret = ssl_tls13_select_ciphersuite_for_resumption(
-                            ssl, ciphersuites, ciphersuites_end, NULL,
+                            ssl, ciphersuites, ciphersuites_end, &session,
                             &cipher_suite, &ciphersuite_info );
+#else
+                ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+#endif
                 break;
             default:
                 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
@@ -547,6 +595,9 @@
             /* For security reasons, the handshake should be aborted when we
              * fail to validate a binder value. See RFC 8446 section 4.2.11.2
              * and appendix E.6. */
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+            mbedtls_ssl_session_free( &session );
+#endif
             MBEDTLS_SSL_DEBUG_MSG( 3, ( "Invalid binder." ) );
             MBEDTLS_SSL_DEBUG_RET( 1,
                 "ssl_tls13_offered_psks_check_binder_match" , ret );
@@ -559,11 +610,24 @@
         matched_identity = identity_id;
 
         /* Update handshake parameters */
-        ssl->session_negotiate->ciphersuite = cipher_suite;
         ssl->handshake->ciphersuite_info = ciphersuite_info;
-        MBEDTLS_SSL_DEBUG_MSG( 2, ( "overwrite ciphersuite: %04x - %s",
-                                    cipher_suite, ciphersuite_info->name ) );
-
+        if( psk_type == MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL )
+        {
+            ssl->session_negotiate->ciphersuite = cipher_suite;
+           MBEDTLS_SSL_DEBUG_MSG( 2, ( "overwrite ciphersuite: %04x - %s",
+                                        cipher_suite,
+                                        ciphersuite_info->name ) );
+        }
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+        else
+        if( psk_type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION )
+        {
+            ret = ssl_tls13_session_copy(ssl->session_negotiate, &session );
+            mbedtls_ssl_session_free( &session );
+            if( ret != 0 )
+                return( ret );
+        }
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
     }
 
     if( p_identity_len != identities_end || p_binder_len != binders_end )