From c00f7037df3607c89323e68db3ab996b7df394de Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Fri, 21 Sep 2018 22:00:42 -0700
Subject: bpo-34759: Fix error handling in ssl 'unwrap()' (GH-9468)

OpenSSL follows the convention that whenever you call a function, it
returns an error indicator value; and if this value is negative, then
you need to go look at the actual error code to see what happened.

Commit c6fd1c1c3a introduced a small mistake in
_ssl__SSLSocket_shutdown_impl: instead of checking whether the error
indicator was negative, it started checking whether the actual error
code was negative, and it turns out that the error codes are never
negative. So the effect was that 'unwrap()' lost the ability to raise
SSL errors.

https://bugs.python.org/issue34759
(cherry picked from commit c0da582b227f311126e278b5553a7fa89c79b054)

Co-authored-by: Nathaniel J. Smith <njs@pobox.com>
---
 Lib/test/test_ssl.py | 41 +++++++++++++++++++++++++++++++++++++++++
 Modules/_ssl.c       |  4 ++--
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 49a4d72..4d5925a 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -1735,6 +1735,47 @@ class SSLObjectTests(unittest.TestCase):
         with self.assertRaisesRegex(TypeError, "public constructor"):
             ssl.SSLObject(bio, bio)
 
+    def test_unwrap(self):
+        client_ctx, server_ctx, hostname = testing_context()
+        c_in = ssl.MemoryBIO()
+        c_out = ssl.MemoryBIO()
+        s_in = ssl.MemoryBIO()
+        s_out = ssl.MemoryBIO()
+        client = client_ctx.wrap_bio(c_in, c_out, server_hostname=hostname)
+        server = server_ctx.wrap_bio(s_in, s_out, server_side=True)
+
+        # Loop on the handshake for a bit to get it settled
+        for _ in range(5):
+            try:
+                client.do_handshake()
+            except ssl.SSLWantReadError:
+                pass
+            if c_out.pending:
+                s_in.write(c_out.read())
+            try:
+                server.do_handshake()
+            except ssl.SSLWantReadError:
+                pass
+            if s_out.pending:
+                c_in.write(s_out.read())
+        # Now the handshakes should be complete (don't raise WantReadError)
+        client.do_handshake()
+        server.do_handshake()
+
+        # Now if we unwrap one side unilaterally, it should send close-notify
+        # and raise WantReadError:
+        with self.assertRaises(ssl.SSLWantReadError):
+            client.unwrap()
+
+        # But server.unwrap() does not raise, because it reads the client's
+        # close-notify:
+        s_in.write(c_out.read())
+        server.unwrap()
+
+        # And now that the client gets the server's close-notify, it doesn't
+        # raise either.
+        c_in.write(s_out.read())
+        client.unwrap()
 
 class SimpleBackgroundTests(unittest.TestCase):
     """Tests that connect to a simple server running in the background"""
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 7ff616e..faca3a2 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -2584,9 +2584,9 @@ _ssl__SSLSocket_shutdown_impl(PySSLSocket *self)
             break;
     }
 
-    if (err.ssl < 0) {
+    if (ret < 0) {
         Py_XDECREF(sock);
-        return PySSL_SetError(self, err.ssl, __FILE__, __LINE__);
+        return PySSL_SetError(self, ret, __FILE__, __LINE__);
     }
     if (sock)
         /* It's already INCREF'ed */
-- 
cgit v0.12