Re: netgroup limits on -current ... [mountd(8)]

On Tue, Feb 21, 2006 at 12:24:35PM +1030, Wilkinson, Alex wrote:
	> OS: FreeBSD 7.0-CURRENT #24: Thu Feb 16 12:28:58 CST 2006
	> 
	> Hi all,
	> 
	> We are currently experiencing problems with FreeBSD -CURRENT and mountd(8).
	> When we export a filesystem via NFS to a netgroup with a 'large' number of hosts
	> in it we get all sorts of truncation. There looks like a limit on the number of
	> hosts in a netgroup FreeBSD's mountd(8) can export to. e.g.
	> 
	> NFS Export
	> ----------
	> 
	> /export/home/username my_netgroup
	> 
	> mountd(8) In Debugging Mode
	> ---------------------------
	> 
	> Feb 21 12:10:49 host mountd[83451]: can't get address info for host hostname.dsto.defence.g
	> Feb 21 12:10:49 host mountd[83451]: bad host host.dsto.defence.g in netgroup my_netgroup, skipping
	> 
	> This happens as mountd(8) builds its exports list via:
	> 
	> mountd: getting export list
	> mountd: got line /export/home/username my_netgroup
	> mountd: making new ep fs=0x4297314f,0x57f85ac
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> got host host.dsto.defence.gov.au
	> 
	> ...
	> 
	> relevant code producing this error:
	> 
	> /usr/src/usr.sbin/mountd
	> 
	>    get_host(cp, grp, tgrp)
	>            char *cp;
	>            struct grouplist *grp;
	>            struct grouplist *tgrp;
	>    {
	>            struct grouplist *checkgrp;
	>            struct addrinfo *ai, *tai, hints;
	>            int ecode;
	>            char host[NI_MAXHOST];
	> 
	>            if (grp->gr_type != GT_NULL) {
	>                    syslog(LOG_ERR, "Bad netgroup type for ip host %s", cp);
	>                    return (1);
	>            }
	>            memset(&hints, 0, sizeof hints);
	>            hints.ai_flags = AI_CANONNAME;
	>            hints.ai_protocol = IPPROTO_UDP;
	>            ecode = getaddrinfo(cp, NULL, &hints, &ai);
	>            if (ecode != 0) {
	>                    syslog(LOG_ERR,"can't get address info for host %s", cp);
	>                    return 1;
	>            }
	>            grp->gr_ptr.gt_addrinfo = ai;
	>            while (ai != NULL) {
	>                    if (ai->ai_canonname == NULL) {
	>                            if (getnameinfo(ai->ai_addr, ai->ai_addrlen, host,
	>                                sizeof host, NULL, 0, NI_NUMERICHOST) != 0)
	>                                    strlcpy(host, "?", sizeof(host));
	>                            ai->ai_canonname = strdup(host);
	>                            ai->ai_flags |= AI_CANONNAME;
	>                    }
	>                    if (debug)
	>                            fprintf(stderr, "got host %s\n", ai->ai_canonname);
	>                    /*
	>                     * Sanity check: make sure we don't already have an entry
	>                     * for this host in the grouplist.
	>                     */
	>                    for (checkgrp = tgrp; checkgrp != NULL;
	>                        checkgrp = checkgrp->gr_next) {
	>                            if (checkgrp->gr_type != GT_HOST)
	>                                    continue;
	>                            for (tai = checkgrp->gr_ptr.gt_addrinfo; tai != NULL;
	>                                tai = tai->ai_next) {
	>                                    if (sacmp(tai->ai_addr, ai->ai_addr, NULL) != 0)
	>                                            continue;
	>                                    if (debug)
	>                                            fprintf(stderr,
	>                                                "ignoring duplicate host %s\n",
	>                                                ai->ai_canonname);
	>                                    grp->gr_type = GT_IGNORE;
	>                                    return (0);
	>                            }
	>                    }
	>                    ai = ai->ai_next;
	>            }
	> 
	> 
	> Can someone please tell me if there is a limit on the number characters or hosts
	> that mountd(8) can build an export list from ? And if so can we increase it ?
	> 
	> Cheers
	> 
	>  - aW

This reminds me of an old problem I had on a solaris 2.5.1 -- it was not possible
to have a "large" number of hosts in the netgroup and (thus) in the export list.
The solution was to split the large netgroup into a number of smaller netgroups,
and then combine them into a large netgroup using the smaller netgroups' names.
We did that with a C program, you could also do that in a script.

The problem was a limit of 255 characters on the length of the 
netgroup list.

I still have the program if you are interested.

-- 
Vladimir