BUG#25444075 - YASSL REQUIRES FROM READ FUNCTION TO RETURN

               EWOULDBLOCK, VIO RETURNS ETIMEOUT.

Connection is invalidated when read timeout occurs and application uses
YaSSL.  The root cause is that yassl_recv emulates a blocking recv using the
vio_read. vio_read returns ETIMEOUT in case of a timeout. YaSSL considers
ETIMEOUT as a critical error causing subsequent read and writes to fail.
The fix remaps ETIMEOUT to EWOULDBLOCK in yassl_recv. This fix is provided
by Lukasz Kotula.

Author: thayumanavar77

vio/viossl.cc

@@ -167,7 +167,13 @@ static my_bool ssl_should_retry(Vio *vio, int ret,
   return should_retry;
 }
 
-
+#ifdef HAVE_YASSL
+size_t vio_ssl_read(Vio *vio, uchar *buf, size_t size)
+{
+  // YASSL maps ETIMEOUT to EWOULDBLOCK and hence no need for retry here.
+  return SSL_read(static_cast<SSL*>(vio->ssl_arg), buf, (int)size);
+}
+#else
 size_t vio_ssl_read(Vio *vio, uchar *buf, size_t size)
 {
   int ret;
@@ -180,14 +186,12 @@ size_t vio_ssl_read(Vio *vio, uchar *buf, size_t size)
   {
     enum enum_vio_io_event event;
 
-#ifndef HAVE_YASSL
     /*
       OpenSSL: check that the SSL thread's error queue is cleared. Otherwise
       SSL_read() returns an error from the error queue, when SSL_read() failed
       because it would block.
     */
     DBUG_ASSERT(ERR_peek_error() == 0);
-#endif
 
     ret= SSL_read(ssl, buf, (int)size);
 
@@ -205,7 +209,7 @@ size_t vio_ssl_read(Vio *vio, uchar *buf, size_t size)
 
   DBUG_RETURN(ret < 0 ? -1 : ret);
 }
-
+#endif
 
 size_t vio_ssl_write(Vio *vio, const uchar *buf, size_t size)
 {
@@ -251,8 +255,15 @@ extern "C" {
 /* Emulate a blocking recv() call with vio_read(). */
 static long yassl_recv(void *ptr, void *buf, size_t len)
 {
-  return static_cast<long>(vio_read(static_cast<Vio*>(ptr),
+  long result= static_cast<long>(vio_read(static_cast<Vio*>(ptr),
                                     static_cast<uchar*>(buf), len));
+  /*
+    YASSL considers ETIMEOUT as critical error. This causes
+    the connection to be invalidated.
+  */
+  if (result == -1 && vio_was_timeout(static_cast<Vio*>(ptr)))
+    errno= SOCKET_EWOULDBLOCK;
+  return result;
 }