I didn't meant blocking as setblocking(True). I use select/poll but I can't use returned value from send() immediately since in Windows there are often needed more send rounds to actually know how much data was sent.

E.g. in Linux I know it after the first call:

  sslsock.write("abcd") -> returns 2
  poll(sslsock)
  sslsock.write("cd")

in Windows I must do:

  sslsock.write("abcd") -> raises SSLError
  poll(sslsock)
  sslsock.write("abcd") -> returns 4

As I wrote it might be inconsistency in OpenSSL and not in Python's wrapper.