(ITS#7937) back-sock does not flush data to socket

[pdg@uow.edu.au]

Full_Name: Peter Gray
Version: 2.4.39
OS: solaris 10
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (130.130.37.84)


The code in back-sock seems to have an error.

It opens a socket, converts the socket fd to a FILE *, and uses fprintf to send
data to the socket. For example, from search.c:


        fprintf( fp, "SEARCH\n" );
        fprintf( fp, "msgid: %ld\n", (long) op->o_msgid );
        sock_print_conn( fp, op->o_conn, si );
        sock_print_suffixes( fp, op->o_bd );
        fprintf( fp, "base: %s\n", op->o_req_dn.bv_val );
        fprintf( fp, "scope: %d\n", op->oq_search.rs_scope );
        fprintf( fp, "deref: %d\n", op->oq_search.rs_deref );
        fprintf( fp, "sizelimit: %d\n", op->oq_search.rs_slimit );
        fprintf( fp, "timelimit: %d\n", op->oq_search.rs_tlimit );
        fprintf( fp, "filter: %s\n", op->_s_search.rs_filterstr.bv_val );
        fprintf( fp, "attrsonly: %d\n", op->oq_search.rs_attrsonly ? 1 : 0 );
        fprintf( fp, "attrs:%s", op->oq_search.rs_attrs == NULL ? " all" : ""
);
        for ( an = op->oq_search.rs_attrs; an && an->an_name.bv_val; an++ ) {
                fprintf( fp, " %s", an->an_name.bv_val );
        }
        fprintf( fp, "\n\n" );  /* end of attr line plus blank line */

        /* read in the results and send them along */
        rs->sr_attrs = op->oq_search.rs_attrs;
        sock_read_and_send_results( op, rs, fp );

However, it fails to flush the stream, so in sock_read_and_send_results when it
issues a read from the socket, the data written has not been seen by the socket
endpoint. 

This results in deadlock when slapd is waiting on the read, and the daemon on
the other end of the socket is waiting on the ldap query.

My fix is to call fflush as the first operation on sock_read_and_send_results
and this worked fine.

Here is the diff.
*** .snapshot/nightly.0/result.c        Sun Jan 26 00:36:15 2014
--- result.c    Thu Sep 11 11:25:07 2014
***************
*** 48,53 ****
--- 48,54 ----
        char    line[BUFSIZ];
        char    ebuf[128];
  
+       (void) fflush(fp);
        /* read in the result and send it along */
        buf = (char *) ch_malloc( BUFSIZ );
        buf[0] = '\0';