[openssl-commits] [openssl] master update

Matt Caswell matt at openssl.org
Fri Sep 8 12:24:17 UTC 2017

The branch master has been updated
       via  bac6abe18d28373e0d2d0666c411020404197337 (commit)
      from  180794c54e98ae467c4ebced3737e1ede03e320a (commit)

- Log -----------------------------------------------------------------
commit bac6abe18d28373e0d2d0666c411020404197337
Author: Matt Caswell <matt at openssl.org>
Date:   Mon Sep 4 11:20:27 2017 +0100

    Allow an endpoint to read the alert data before closing the socket
    If an alert gets sent and then we close the connection immediately with
    data still in the input buffer then a TCP-RST gets sent. Some OSs
    immediately abandon data in their input buffer if a TCP-RST is received -
    meaning the alert data itself gets ditched. Sending a TCP-FIN before the
    TCP-RST seems to avoid this.
    This was causing test failures in MSYS2 builds.
    Reviewed-by: Rich Salz <rsalz at openssl.org>
    Reviewed-by: Ben Kaduk <kaduk at mit.edu>
    (Merged from https://github.com/openssl/openssl/pull/4333)


Summary of changes:
 apps/s_socket.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/apps/s_socket.c b/apps/s_socket.c
index 3bdb587..2f3e90b 100644
--- a/apps/s_socket.c
+++ b/apps/s_socket.c
@@ -221,6 +221,23 @@ int do_server(int *accept_sock, const char *host, const char *port,
             i = (*cb)(sock, type, protocol, context);
+            /*
+             * If we ended with an alert being sent, but still with data in the
+             * network buffer to be read, then calling BIO_closesocket() will
+             * result in a TCP-RST being sent. On some platforms (notably
+             * Windows) then this will result in the peer immediately abandoning
+             * the connection including any buffered alert data before it has
+             * had a chance to be read. Shutting down the sending side first,
+             * and then closing the socket sends TCP-FIN first followed by
+             * TCP-RST. This seems to allow the peer to read the alert data.
+             */
+#ifdef _WIN32
+# ifdef SD_SEND
+            shutdown(sock, SD_SEND);
+# endif
+#elif defined(SHUT_WR)
+            shutdown(sock, SHUT_WR);
         } else {
             i = (*cb)(asock, type, protocol, context);

More information about the openssl-commits mailing list