dname.c

/*
 * Part of DNS zone file validator `validns`.
 *
 * Copyright 2011-2014 Anton Berezin <tobez@tobez.org>
 * Modified BSD license.
 * (See LICENSE file in the distribution.)
 *
 */
#include <sys/types.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "common.h"
#include "textparse.h"
#include "mempool.h"
#include "carp.h"
#include "rr.h"

/* DNAMEs are described in http://tools.ietf.org/html/rfc2672 */

static struct rr *dname_parse(char *name, long ttl, int type, char *s)
{
    struct rr_dname *rr = getmem(sizeof(*rr));

    rr->target = extract_name(&s, "dname target", 0);
    if (!rr->target)
        return NULL;
    if (*s) {
        return bitch("garbage after valid DNAME data");
    }

    return store_record(type, name, ttl, rr);
}

static char* dname_human(struct rr *rrv)
{
    RRCAST(dname);
    return rr->target;
}

static struct binary_data dname_wirerdata(struct rr *rrv)
{
    RRCAST(dname);
    return name2wire_name(rr->target);
}

static void* dname_validate_set(struct rr_set *rr_set)
{
    struct rr *rr;
    struct rr_set *suspect;
    int count;
    struct named_rr *named_rr, *next_named_rr;

    if (G.opt.policy_checks[POLICY_DNAME]) {
        named_rr = rr_set->named_rr;
        rr = rr_set->tail;
        if (rr_set->count > 1)
            return moan(rr->file_name, rr->line, "multiple DNAMEs");
        /* This check is already handled by "CNAME and other data" in cname.c *
        another_set = find_rr_set_in_named_rr(named_rr, T_CNAME);
        if (another_set)
            return moan(rr->file_name, rr->line, "DNAME cannot co-exist with a CNAME");
        */
        next_named_rr = find_next_named_rr(named_rr);
        /* handle http://tools.ietf.org/html/rfc5155#section-10.2 case */
        if (next_named_rr && next_named_rr->parent == named_rr && (named_rr->flags & NAME_FLAG_APEX)) {
            count = get_rr_set_count(next_named_rr);
            if (count > 0) {
                suspect = find_rr_set_in_named_rr(next_named_rr, T_RRSIG);
                if (suspect)    count--;
                suspect = find_rr_set_in_named_rr(next_named_rr, T_NSEC3);
                if (suspect)    count--;
                if (count == 0)
                    next_named_rr = find_next_named_rr(next_named_rr);
            }
        }
        if (next_named_rr && next_named_rr->parent == named_rr)
            return moan(rr->file_name, rr->line,
                        "DNAME must not have any children (but %s exists)",
                        next_named_rr->name);
    }
    return NULL;
}

struct rr_methods dname_methods = { dname_parse, dname_human, dname_wirerdata, dname_validate_set, NULL };