From 8313a787d770ac1d7ddafcbc41b13e7fb5841eae Mon Sep 17 00:00:00 2001 From: Benjamin Kaduk Date: Tue, 7 Feb 2017 16:23:16 -0600 Subject: Allow an ALPN callback to pretend to not exist RFC 7301 mandates that the server SHALL respond with a fatal "no_application_protocol" alert when there is no overlap between the client's supplied list and the server's list of supported protocols. In commit 062178678f5374b09f00d70796f6e692e8775aca we changed from ignoring non-success returns from the supplied alpn_select_cb() to treating such non-success returns as indicative of non-overlap and sending the fatal alert. In effect, this is using the presence of an alpn_select_cb() as a proxy to attempt to determine whether the application has configured a list of supported protocols. However, there may be cases in which an application's architecture leads it to supply an alpn_select_cb() but have that callback be configured to take no action on connections that do not have ALPN configured; returning SSL_TLSEXT_ERR_NOACK from the callback would be the natural way to do so. Unfortunately, the aforementioned behavior change also treated SSL_TLSEXT_ERR_NOACK as indicative of no overlap and terminated the connection; this change supplies special handling for SSL_TLSEXT_ERR_NOACK returns from the callback. In effect, it provides a way for a callback to obtain the behavior that would have occurred if no callback was registered at all, which was not possible prior to this change. Reviewed-by: Matt Caswell Reviewed-by: Rich Salz (Merged from https://github.com/openssl/openssl/pull/2570) --- test/handshake_helper.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'test/handshake_helper.c') diff --git a/test/handshake_helper.c b/test/handshake_helper.c index 47af3fe396..94fa5c578f 100644 --- a/test/handshake_helper.c +++ b/test/handshake_helper.c @@ -413,7 +413,7 @@ static int server_alpn_cb(SSL *s, const unsigned char **out, *out = tmp_out; /* Unlike NPN, we don't tolerate a mismatch. */ return ret == OPENSSL_NPN_NEGOTIATED ? SSL_TLSEXT_ERR_OK - : SSL_TLSEXT_ERR_NOACK; + : SSL_TLSEXT_ERR_ALERT_FATAL; } #ifndef OPENSSL_NO_SRP -- cgit v1.2.3