From: Richard Braakman <dark@xs4all.nl>
Message-Id: <199703160506.GAA04489@xs1.xs4all.nl>
Subject: nn dumps core if NNTPSERVER is invalid
To: bugs@bugs.debian.org
Date: Sun, 16 Mar 1997 06:06:08 +0100 (MET)
MIME-Version: 1.0
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Package: nn
Version: 6.5.0.b3.linux.1.1-01

When I start nn while the environment variable NNTPSERVER cannot be
found by gethostbyname(), it dumps core immediately.  I have traced
the problem to the function nntp_check() in nntp.c.  I quote it here.
The problem line has been marked with an arrow in the left margin.

/*
 * nntp_check: Find out whether we need to use NNTP.
 *
 *      This is done by comparing the NNTP servers name with whatever
 *      nn_gethostname() returns.
 *      use_nntp and news_active are initialised as a side effect.
 */

nntp_check()
{
    char host[128];
    const char *server_real_name;

    if (nntp_local_server) return;

    find_server();
    nn_gethostname(host, sizeof host);
    strncpy(host, (gethostbyname(host))->h_name, sizeof host);

--> server_real_name = (gethostbyname(nntp_server))->h_name;
    use_nntp = (strcmp(host, server_real_name) != 0);

    if (use_nntp) {
        freeobj(news_active);
#ifndef NOV
        news_active = mk_file_name(db_directory, "ACTIVE");
#else /* NOV */
        news_active = mk_file_name(nn_directory, "ACTIVE");
#endif /* NOV */
    }
}


The function gethostbyname() will return 0 if the lookup fails for any
reason.  The subsequent dereference will cause the program to dump
core.