Open Radar

 
Area:
Networking

Summary:
When you call SecureTransport's SSLClose() method, it will send the close_notify alert
and then flag the connection as closed for reading and writing.

Subsequent calls to SSLRead() will immediately return errSSLClosedGraceful without
actually reading anything.

This is a problem if the remote sends a close_notify alert back - as required by
section 7.2.1 of the TLS 1.2 spec (RFC 5246) - and you want to reuse the underlying
transport.

Other TLS 1.2 implementations such as OpenSSL or BoringSSL allow reading after
shutdown - and the read returns "closed gracefully" after the close_notify reply has been
received.

Steps to Reproduce:
Use SecureTransport to establish a secure connection to a TLS 1.2 server.  Make sure that upon receiving a close_notify alert, the server send a close_notify back (SecureTransport does that).
Wait until the server has sent some data.
Call SSLClose(), then SSLRead().

Expected Results:
SSLClose() should only make the connection as closed for writing, but still allow reading.
SSLRead() should read everything the server sent - including the close_notify - then return errSSLClosedGraceful.

Observed Results:
SSLRead() returns immediately with errSSLClosedGraceful, without actually reading anything.

Version:
10.12.5

Notes:
This makes it impossible to reuse the underlying transport as there is no way of reading the server's (encrypted) close_notify reply.