It seems to me that when the Curl_Send function
returns 0, then either the openssl statemachine had returned
SSL_ERROR_WANT_READ or
SSL_ERROR_WANT_WRITE.

  rc = SSL_write(conn->ssl[sockindex].handle, mem, memlen);

  if(rc < 0) {
    err = SSL_get_error(conn->ssl[sockindex].handle, rc);

    switch(err) {
    case SSL_ERROR_WANT_READ:
    case SSL_ERROR_WANT_WRITE:
      /* The operation did not complete; the same TLS/SSL I/O function
         should be called again later. This is basicly an EWOULDBLOCK
         equivalent. */
      return 0;

Depending on that one must select for reading or writing,
(in a loop), but how?

http://www.openssl.org/docs/ssl/SSL_get_error.html
Received on 2009-08-19