Add SSL_OP_ALLOW_CLIENT_RENEGOTIATION

Add -client_renegotiation flag support.  The -client_renegotiation flag is
equivalent to SSL_OP_ALLOW_CLIENT_RENEGOTIATION. Add support to the app,
the config code, and the documentation.

Add SSL_OP_ALLOW_CLIENT_RENEGOTIATION to the SSL tests. We don't need to
always enable it, but there are so many tests so this is the easiest thing
to do.

Add a test where client tries to renegotiate and it fails as expected. Add
a test where server tries to renegotiate and it succeeds. The second test
is supported by a new flag, -immediate_renegotiation, which is ignored on
the client.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15184)

1 files changed, 15 insertions, 12 deletions

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 047fa1a07d..ff13442e3b 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2277,39 +2277,42 @@ int SSL_get_key_update_type(const SSL *s)
     return s->key_update;
 }
 
-int SSL_renegotiate(SSL *s)
+/*
+ * Can we accept a renegotiation request?  If yes, set the flag and
+ * return 1 if yes. If not, raise error and return 0.
+ */
+static int can_renegotiate(const SSL *s)
 {
     if (SSL_IS_TLS13(s)) {
         ERR_raise(ERR_LIB_SSL, SSL_R_WRONG_SSL_VERSION);
         return 0;
     }
 
-    if ((s->options & SSL_OP_NO_RENEGOTIATION)) {
+    if ((s->options & SSL_OP_NO_RENEGOTIATION) != 0) {
         ERR_raise(ERR_LIB_SSL, SSL_R_NO_RENEGOTIATION);
         return 0;
     }
 
+    return 1;
+}
+
+int SSL_renegotiate(SSL *s)
+{
+    if (!can_renegotiate(s))
+        return 0;
+
     s->renegotiate = 1;
     s->new_session = 1;
-
     return s->method->ssl_renegotiate(s);
 }
 
 int SSL_renegotiate_abbreviated(SSL *s)
 {
-    if (SSL_IS_TLS13(s)) {
-        ERR_raise(ERR_LIB_SSL, SSL_R_WRONG_SSL_VERSION);
+    if (!can_renegotiate(s))
         return 0;
-    }
-
-    if ((s->options & SSL_OP_NO_RENEGOTIATION)) {
-        ERR_raise(ERR_LIB_SSL, SSL_R_NO_RENEGOTIATION);
-        return 0;
-    }
 
     s->renegotiate = 1;
     s->new_session = 0;
-
     return s->method->ssl_renegotiate(s);
 }