From 206dcead747e04e97c0d9c54d77cf0b5e4636f7a Mon Sep 17 00:00:00 2001

From: Melvyn Sopacua <melvyn-sopacua@users.noreply.github.com>

Date: Mon, 4 Sep 2017 23:35:15 +0200

Subject: [PATCH] [2.7] bpo-30622: Change NPN detection: (GH-2079)

* Change NPN detection:

Version breakdown, support disabled (pre-patch/post-patch):

- pre-1.0.1: OPENSSL_NPN_NEGOTIATED will not be defined -> False/False

- 1.0.1 and 1.0.2: OPENSSL_NPN_NEGOTIATED will not be defined ->

False/False

- 1.1.0+: OPENSSL_NPN_NEGOTIATED will be defined and

OPENSSL_NO_NEXTPROTONEG will be defined -> True/False

Version breakdown support enabled (pre-patch/post-patch):

- pre-1.0.1: OPENSSL_NPN_NEGOTIATED will not be defined -> False/False

- 1.0.1 and 1.0.2: OPENSSL_NPN_NEGOTIATED will be defined and

OPENSSL_NO_NEXTPROTONEG will not be defined -> True/True

- 1.1.0+: OPENSSL_NPN_NEGOTIATED will be defined and

OPENSSL_NO_NEXTPROTONEG will not be defined -> True/True

* Refine NPN guard:

- If NPN is disabled, but ALPN is available we need our callback

- Make clinic's ssl behave the same way

This created a working ssl module for me, with NPN disabled and ALPN

enabled for OpenSSL 1.1.0f.

Concerns to address:

The initial commit for NPN support into OpenSSL [1], had the

OPENSSL_NPN_* variables defined inside the OPENSSL_NO_NEXTPROTONEG

guard. The question is if that ever made it into a release.

This would need an ugly hack, something like:

	GH-if defined(OPENSSL_NO_NEXTPROTONEG) && \

		!defined(OPENSSL_NPN_NEGOTIATED)

	GH-	define OPENSSL_NPN_UNSUPPORTED 0

	GH-	define OPENSSL_NPN_NEGOTIATED 1

	GH-	define OPENSSL_NPN_NO_OVERLAP 2

	GH-endif

[1] https://github.com/openssl/openssl/commit/68b33cc5c7.

(cherry picked from commit b2d096bd2a5ff86e53c25d00ee5fa097b36bf1d8)

---

 Modules/_ssl.c | 16 +++++++++-------

 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/Modules/_ssl.c b/Modules/_ssl.c

index 213c7d21510..832b5f96bff 100644

--- Modules/_ssl.c.orig

+++ Modules/_ssl.c

@@ -280,7 +280,7 @@ static unsigned int _ssl_locks_count = 0;

 typedef struct {

     PyObject_HEAD

     SSL_CTX *ctx;

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

     unsigned char *npn_protocols;

     int npn_protocols_len;

 #endif

@@ -1502,7 +1502,7 @@ static PyObject *PySSL_version(PySSLSocket *self)

     return PyUnicode_FromString(version);

 }

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

 static PyObject *PySSL_selected_npn_protocol(PySSLSocket *self) {

     const unsigned char *out;

     unsigned int outlen;

@@ -2030,7 +2030,7 @@ static PyMethodDef PySSLMethods[] = {

      PySSL_peercert_doc},

     {"cipher", (PyCFunction)PySSL_cipher, METH_NOARGS},

     {"version", (PyCFunction)PySSL_version, METH_NOARGS},

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

     {"selected_npn_protocol", (PyCFunction)PySSL_selected_npn_protocol, METH_NOARGS},

 #endif

 #ifdef HAVE_ALPN

@@ -2140,7 +2140,7 @@ context_new(PyTypeObject *type, PyObject *args, PyObject *kwds)

         return NULL;

     }

     self->ctx = ctx;

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

     self->npn_protocols = NULL;

 #endif

 #ifdef HAVE_ALPN

@@ -2218,7 +2218,7 @@ context_dealloc(PySSLContext *self)

     PyObject_GC_UnTrack(self);

     context_clear(self);

     SSL_CTX_free(self->ctx);

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

     PyMem_FREE(self->npn_protocols);

 #endif

 #ifdef HAVE_ALPN

@@ -2248,7 +2248,7 @@ set_ciphers(PySSLContext *self, PyObject *args)

     Py_RETURN_NONE;

 }

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG) || 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,

@@ -2272,7 +2272,9 @@ do_protocol_selection(int alpn, unsigned char **out, unsigned char *outlen,

     return SSL_TLSEXT_ERR_OK;

 }

+#endif

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

 /* this callback gets passed to SSL_CTX_set_next_protos_advertise_cb */

 static int

 _advertiseNPN_cb(SSL *s,

@@ -2307,7 +2309,7 @@ _selectNPN_cb(SSL *s,

 static PyObject *

 _set_npn_protocols(PySSLContext *self, PyObject *args)

 {

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

     Py_buffer protos;

     if (!PyArg_ParseTuple(args, "s*:set_npn_protocols", &protos))

@@ -4305,7 +4307,7 @@ init_ssl(void)

     Py_INCREF(r);

     PyModule_AddObject(m, "HAS_ECDH", r);

-#ifdef OPENSSL_NPN_NEGOTIATED

+#if defined(OPENSSL_NPN_NEGOTIATED) && !defined(OPENSSL_NO_NEXTPROTONEG)

     r = Py_True;

 #else

     r = Py_False;