Dr. Stephen Henson wrote:
On Wed, Sep 12, 2007, Jim Marshall wrote:
I have setup my BIO to be non-blocking in my server. In my server I want
to use 'select' to detect when there is a connection available, but for
some reason it is not working. either select returns '-1' with errno set
to EINTR or select returns 0, but it has not waited for 2 seconds for a
connection. Maybe someone can give me an idea what I am doing wrong?
here is the code I am using:
void startListening(BIO* sock) {
int acceptSock = BIO_get_fd(sock, NULL);
int waitVal = 0;
fd_set rfds, wfds, efds;
struct timeval tv;
/* Wait up to two seconds. */
tv.tv_sec = 2;
tv.tv_usec = 0;
/* This is just one of the tests I have tried */
FD_ZERO(&rfds);
FD_SET(acceptSock, &rfds);
FD_ZERO(&wfds);
FD_SET(acceptSock, &wfds);
FD_ZERO(&rfds);
FD_SET(acceptSock, &efds);
do {
/* see if we have any activity on the socket */
waitVal = select(acceptSock, &rfds, &wfds, &efds, &tv);
if (waitVal < 0)
{
char* err = strerror(errno);
printf("select error: %s\n", err);
fflush(stdout);
return;
} if (waitVal > 0) {
BIO_do_accept(sock)
handleAccept(sock);
}
} while (waitVal == 0);
...
}
If I change this code to do a 'BIO_do_accept' and the call 'sleep(1)'
when 'BIO_do_accept' returns -1 and errno is EAGAIN it seems to work
fine. But that means my server could be sleeping when a request come in.
Any thoughts?
Thanks
Jim
p.s.
The BIO passed into the function above is created like this:
ret = BIO_new_accept(hostString);
if (ret != NULL)
{
/* set the accept socket to non-blocking */
BIO_set_nbio_accept(ret, 1);
/* set sockets created from this accept socket to
non-blocking */
BIO_set_nbio(ret, 1);
BIO_set_bind_mode(ret, BIO_BIND_REUSEADDR);
/* bind & listen */
val = BIO_do_accept(ret)
...
it is returned to a calling function which in turn calls startListening.
Well you should loop round calling BIO_do_accept() in the startListening()
function and not call it outside. Check the return value and if >0 a
connection has occurred and you can process it.
If <=0 check the status with BIO_should_retry() if that returns 0 some error
has occurred.
If BIO_should_retry() is true get the fd from the BIO and wait for a
connection condition: what you wait for depends on the OS but select (or
similar) for a read condition is typical.
Steve.
--
Dr Stephen N. Henson. Email, S/MIME and PGP keys: see homepage
OpenSSL project core developer and freelance consultant.
Funding needed! Details on homepage.
Homepage: http://www.drh-consultancy.demon.co.uk
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Hi Steve,
Thanks again for your help. What you suggested is very similar to what
I was doing orginally (although I was using errno and not
BIO_should_retry). When the code is setup as you describe (see code
below) what happens is that the first couple of times the 'select' call
is made it returns with a -1 with errno set to EINTR. If I let it
continue it does this like 4 times and then select 'seems' to start
working, in that it will actually timeout (wait 2 seconds before
returning). However client connections are never detected. For example
if I connect with the openssl command line tool, the tool says
"CONNECTED(00000003)"
But select just continues to return 0 (and the app pauses for 2 seconds
at a time).
void startListening(BIO* sock)
{
int acceptRet = -1;
acceptRet = BIO_do_accept(sock);
if (acceptRet > 0)
{
BIO* client = NULL;
SSL* ssl = NULL;
client = BIO_pop(sock);
BIO_set_nbio_accept(client, 1);
ssl = SSL_new(gCtx);
if (ssl != NULL)
{
SSL_set_bio(ssl, client, client);
SSL_set_accept_state(ssl);
starthandler(ssl))
} else {
handleSSLError("SSL_startListening");
}
} else {
if (BIO_should_retry(sock) == 0)
{
int reason = 0;
(void) BIO_get_retry_BIO(sock, &reason);
printf("SSL_startListening: BIO_do_accept returned %d,
error: %s",
reason, strerror(reason));
} else {
int waitVal = 0;
acceptRet = BIO_get_fd(sock, NULL);
do {
fd_set fds;
struct timeval tv;
/* Wait up to two seconds. */
tv.tv_sec = 2;
tv.tv_usec = 0;
/* Watch the socket to see when it has input. */
FD_ZERO(&fds);
FD_SET(acceptRet, &fds);
/* see if we have any activity on the socket */
waitVal = select(acceptRet, &fds, NULL, NULL, &tv);
if (waitVal < 0)
{
char* err = strerror(errno);
printf("select error: %s\n", err);
fflush(stdout);
if (errno != EINTR) return;
}
} while (waitVal == 0);
}
}
}
Note if I change the final else clause to just do a "Sleep(1)" I can
accept connections no problem.
I appreciate any feedback. I'm sure I'm doing something wrong...
Thanks
Jim
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