[2.7] bpo-30622: Improve NPN support detection (GH-5859) (#5863)
The ssl module now detects missing NPN support in LibreSSL.
Co-Authored-By: Bernard Spil <brnrd@FreeBSD.org>
Signed-off-by: Christian Heimes <christian@python.org>.
(cherry picked from commit 6cdb7954b0a578d899e4b78b868ea59eef08480a)
Co-authored-by: Christian Heimes <christian@python.org>
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index f09f9c9..af66a58 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -127,6 +127,19 @@
# define HAVE_ALPN
#endif
+/* We cannot rely on OPENSSL_NO_NEXTPROTONEG because LibreSSL 2.6.1 dropped
+ * NPN support but did not set OPENSSL_NO_NEXTPROTONEG for compatibility
+ * reasons. The check for TLSEXT_TYPE_next_proto_neg works with
+ * OpenSSL 1.0.1+ and LibreSSL.
+ */
+#ifdef OPENSSL_NO_NEXTPROTONEG
+# define HAVE_NPN 0
+#elif defined(TLSEXT_TYPE_next_proto_neg)
+# define HAVE_NPN 1
+#else
+# define HAVE_NPN 0
+# endif
+
#ifndef INVALID_SOCKET /* MS defines this */
#define INVALID_SOCKET (-1)
#endif
@@ -285,7 +298,7 @@
typedef struct {
PyObject_HEAD
SSL_CTX *ctx;
-#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)
+#ifdef HAVE_NPN
unsigned char *npn_protocols;
int npn_protocols_len;
#endif
@@ -2195,7 +2208,7 @@
return NULL;
}
self->ctx = ctx;
-#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)
+#ifdef HAVE_NPN
self->npn_protocols = NULL;
#endif
#ifdef HAVE_ALPN
@@ -2273,7 +2286,7 @@
PyObject_GC_UnTrack(self);
context_clear(self);
SSL_CTX_free(self->ctx);
-#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)
+#ifdef HAVE_NPN
PyMem_FREE(self->npn_protocols);
#endif
#ifdef HAVE_ALPN
@@ -2303,7 +2316,7 @@
Py_RETURN_NONE;
}
-#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG) || defined(HAVE_ALPN)
+#if defined(HAVE_NPN) || defined(HAVE_ALPN)
static int
do_protocol_selection(int alpn, unsigned char **out, unsigned char *outlen,
const unsigned char *server_protocols, unsigned int server_protocols_len,
@@ -2329,7 +2342,7 @@
}
#endif
-#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)
+#ifdef HAVE_NPN
/* this callback gets passed to SSL_CTX_set_next_protos_advertise_cb */
static int
_advertiseNPN_cb(SSL *s,
@@ -2364,7 +2377,7 @@
static PyObject *
_set_npn_protocols(PySSLContext *self, PyObject *args)
{
-#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)
+#ifdef HAVE_NPN
Py_buffer protos;
if (!PyArg_ParseTuple(args, "s*:set_npn_protocols", &protos))
@@ -4373,7 +4386,7 @@
Py_INCREF(r);
PyModule_AddObject(m, "HAS_ECDH", r);
-#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)
+#ifdef HAVE_NPN
r = Py_True;
#else
r = Py_False;