From c0da582b227f311126e278b5553a7fa89c79b054 Mon Sep 17 00:00:00 2001
From: "Nathaniel J. Smith" <njs@pobox.com>
Date: Fri, 21 Sep 2018 21:44:12 -0700
Subject: [PATCH] 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
---
 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 e120a2f9adf22e..b4cafc15c5cdcb 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -1715,6 +1715,47 @@ def test_private_init(self):
         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 4750b930c64293..5b5d7dd445d27b 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -2583,9 +2583,9 @@ _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 */