SSL_accept takes 200ms (c / openssl) - c++

Question

Is it normal that SSL_accept(ssl) takes 200 ms?
Running as a windows service, written in c++, using MFC and Boost. Running on an intel xeon e5620 2.4G, with 4GB memory, and Win 7 Pro.
Following is my code. I meanwhile suspected that maybe other methods before SSL_accept (SSL_CTX_* RAND_* etc) might consume long time , but I logged everthing and discovered that SSL_accept is eating all the time.
int verify_callback(int preverify_ok, X509_STORE_CTX *ctx)
{
return preverify_ok;
}
void somemethod() {
SSL *ssl = 0;
SSL_CTX *tlsctx = 0;
int ret_conn = -1;
tlsctx = SSL_CTX_new( SSLv23_method());
SSL_CTX_use_certificate_file(tlsctx, sCert , SSL_FILETYPE_PEM);
SSL_CTX_use_PrivateKey_file(tlsctx, sKey , SSL_FILETYPE_PEM);
RAND_write_file(sRandomPem);
int _rand_loaded = RAND_load_file(sRandomPem, -1 );
if(! SSL_CTX_load_verify_locations(tlsctx, sCACert, NULL))
{
// TODO // /* Handle error here */
}
SSL_CTX_set_verify( tlsctx, SSL_VERIFY_PEER, verify_callback );
ssl = SSL_new(tlsctx);
int _error = SSL_ERROR_WANT_READ;
int loopCount = 0;
// START MEASURING TIME FROM HERE
SSL_set_fd(ssl, _sck);
while(ret_conn != 1 )
{
loopCount++;
ret_conn = SSL_accept(ssl);
_error = SSL_get_error(ssl, ret_conn);
switch (_error)
{
case SSL_ERROR_NONE:
break;
case SSL_ERROR_WANT_WRITE:
break;
case SSL_ERROR_WANT_READ:
break;
case SSL_ERROR_WANT_X509_LOOKUP:
break;
case SSL_ERROR_SYSCALL:
break;
case SSL_ERROR_SSL:
break;
case SSL_ERROR_ZERO_RETURN:
break;
}
if( _error == SSL_ERROR_WANT_READ || _error == SSL_ERROR_WANT_WRITE)
{
Sleep(1);
} else
{
break;
}
}
if( ret_conn < 1)
{
Log("SSL_accept -1 ", ERR_error_string(_error, NULL));
return;
}
// MEASURING END HERE, takes ~200ms (on successfully accepting connection)
}

Answer 1

To my knowledge, SSL_accept is a blocking function, which waits for your client to connect. If your client connect 200 ms later than the beginning for the SSL_accept call, then you will measure that waiting time.