Add SSL_SESSION_is_resumable() implementation shim

This commit adds SSL_SESSION_is_resumable() implementation if it is
missing.

(cherry picked from commit 35338b4105)

configure.ac

@@ -663,6 +663,7 @@ AC_CHECK_FUNCS([SSL_CTX_set_min_proto_version])
 AC_CHECK_FUNCS([SSL_CTX_up_ref])
 AC_CHECK_FUNCS([SSL_read_ex SSL_peek_ex SSL_write_ex])
 AC_CHECK_FUNCS([SSL_CTX_set1_cert_store X509_STORE_up_ref])
+AC_CHECK_FUNCS([SSL_SESSION_is_resumable])
 
 #
 # Check for algorithm support in OpenSSL

lib/isc/openssl_shim.c

@@ -196,3 +196,11 @@ SSL_CTX_set1_cert_store(SSL_CTX *ctx, X509_STORE *store) {
 }
 
 #endif /* !HAVE_SSL_CTX_SET1_CERT_STORE */
+
+#if !HAVE_SSL_SESSION_IS_RESUMABLE
+int
+SSL_SESSION_is_resumable(const SSL_SESSION *sess) {
+	return (!sess->not_resumable &&
+		(sess->session_id_length > 0 || sess->tlsext_ticklen > 0));
+}
+#endif /* HAVE_SSL_SESSION_IS_RESUMABLE */

lib/isc/openssl_shim.h

@@ -135,3 +135,8 @@ X509_STORE_up_ref(X509_STORE *v);
 void
 SSL_CTX_set1_cert_store(SSL_CTX *ctx, X509_STORE *store);
 #endif /* !HAVE_SSL_CTX_SET1_CERT_STORE */
+
+#if !HAVE_SSL_SESSION_IS_RESUMABLE
+int
+SSL_SESSION_is_resumable(const SSL_SESSION *s);
+#endif /* HAVE_SSL_SESSION_IS_RESUMABLE */