> On Tue, Apr 13, 1999 at 12:00:00AM +0000, Andrew Cooke wrote:
>
> > I am reading across the network, using SSLeay-0.9.0.b, and have an
> > intermittent problem - the sending socket is being closed, but this is
> > not always being detected by the receiving SSL. In particular,
> >
> > SSL_read(ssl, buffer, length)
> >
> > is returning zero rather than -1.
>
> The return value zero means that the connection has been closed (well,
> unless you called read() with length == 0, which does not make too
> much sense). Look at s_client.c: First there's the call
>
> k = SSL_read(con, ...),
>
> and then there's
>
> switch (SSL_get_error(con, k)).
>
The notion is that we should be able to implement code that looks
like:
if (ssl_active_flag || tls_active_flag) {
int error;
if ( ssl_active_flag )
count = SSL_read(ssl_con, buf, sizeof(buf));
else
count = SSL_read(tls_con, buf, sizeof(buf));
switch ( SSL_get_error(ssl_active_flag?ssl_con:tls_con,count)) {
case SSL_ERROR_NONE:
if (count > 0) {
/* Reset buffer pointer. */
return(count); /* Return buffer count. */
} else if (count < 0) {
return(-1); /* Non-fatal error */
} else {
/* count == 0 : close connection */
netclos();
return(-2); /* Fatal Error */
}
case SSL_ERROR_WANT_WRITE:
case SSL_ERROR_WANT_READ:
return(-1); /* Non-fatal error */
case SSL_ERROR_SYSCALL:
switch (WSAGetLastError()) {
case WSAESHUTDOWN:
case WSAECONNABORTED:
netclos();
return(-2);
default: return(-1); /* Non-fatal error */
}
case SSL_ERROR_WANT_X509_LOOKUP:
case SSL_ERROR_SSL:
case SSL_ERROR_ZERO_RETURN:
default:
netclos();
return(-2);
}
}
Now on Windows NT SP4 this code does not detect the closing of the
socket by the peer. SSL_ERROR_ZERO_RETURN is never returned by
SSL_get_error(). When the peer closes the connection SSL_get_error()
starts to return SSL_ERROR_SSYCALL. But WSAGetLastError() returns
NO_ERROR (0).
If the application attempts to write using SSL_write() SSL_get_error()
returns SSL_ERROR_SYSCALL with WSAGetLastError() returning
WSAESHUTDOWN. Subsequent SSL_read() calls will produce a
WSAGetLastError() of WSAECONNABORTED.
If I am doing something wrong, please advise. Otherwise, I still
believe that there is something wrong in the code (at least on
Windows.)
Jeffrey Altman * Sr.Software Designer * Kermit-95 for Win32 and OS/2
The Kermit Project * Columbia University
612 West 115th St #716 * New York, NY * 10025
http://www.kermit-project.org/k95.html * [EMAIL PROTECTED]
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