+static adns_status copy_cname_from_child(adns_query parent, adns_query child)
+{
+ adns_answer *pans = parent->answer, *cans = child->answer;
+ size_t n = strlen(cans->cname) + 1;
+
+ pans->cname = adns__alloc_preserved(parent, n);
+ if (!pans->cname) R_NOMEM;
+ memcpy(pans->cname, cans->cname, n);
+ return adns_s_ok;
+}
+
+static void icb_addr(adns_query parent, adns_query child)
+{
+ adns_state ads = parent->ads;
+ adns_answer *pans = parent->answer, *cans = child->answer;
+ struct timeval tvbuf;
+ adns_status err;
+ const struct timeval *now = 0;
+ adns_rrtype rrty[ADDR_MAXRRTYPES], ty;
+ byte *p;
+ adns_rr_addr *a;
+ int i, j, id;
+ size_t nrrty;
+
+ if (!(child->flags & adns__qf_addr_cname) &&
+ (parent->flags & adns__qf_addr_answer) &&
+ (!pans->cname != !cans->cname ||
+ (pans->cname && strcmp(pans->cname, pans->cname) != 0))) {
+ /* We've detected an inconsistency in CNAME records, and must deploy
+ * countermeasures.
+ */
+
+ if (!pans->cname) {
+ /* The child has a CNAME record, but the parent doesn't. We must
+ * discard all of the parent's addresses, and substitute the child's.
+ */
+
+ assert(pans->rrsz == cans->rrsz);
+ adns__free_interim(parent, pans->rrs.bytes);
+ adns__transfer_interim(child, parent, cans->rrs.bytes);
+ pans->rrs.bytes = cans->rrs.bytes;
+ pans->nrrs = cans->nrrs;
+ err = copy_cname_from_child(parent, child); if (err) goto x_err;
+ }
+
+ /* We've settled on the CNAME (now) associated with the parent, which
+ * already has appropriate address records. Build a query datagram for
+ * this name so that we can issue child queries for the missing address
+ * families. The child's vbuf looks handy for this.
+ */
+ err = adns__mkquery(ads, &child->vb, &id, pans->cname,
+ strlen(pans->cname), adns__findtype(adns_r_addr),
+ adns_r_addr, parent->flags);
+ if (err) goto x_err;
+
+ /* Work out which address rrtypes we want but don't have. */
+ addr_rrtypes(ads, pans->type, parent->flags, rrty, &nrrty);
+ for (i = 0, p = pans->rrs.bytes; i < pans->nrrs; i++, p += pans->rrsz) {
+ a = (adns_rr_addr *)p;
+ ty = 0;
+ switch (a->addr.sa.sa_family) {
+ case AF_INET: ty = adns_r_a; break;
+ case AF_INET6: ty = adns_r_aaaa; break;
+ }
+ assert(ty);
+ for (j = 0; j < nrrty && ty != (rrty[j] & adns_rrt_typemask); j++);
+ if (j < nrrty) rrty[j] = rrty[--nrrty];
+ }
+ assert(nrrty);
+
+ /* Now cancel the remaining children, and try again with the CNAME we've
+ * settled on.
+ */
+ adns__cancel_children(parent);
+ adns__must_gettimeofday(ads, &now, &tvbuf);
+ if (now) {
+ addr_subqueries(parent, *now, child->vb.buf,
+ child->vb.used, rrty, nrrty);
+ }
+ return;
+ }
+
+ if (cans->cname && !pans->cname) {
+ err = copy_cname_from_child(parent, child);
+ if (err) goto x_err;
+ }
+
+ if ((parent->flags & adns_qf_search) &&
+ !pans->cname && cans->status == adns_s_nxdomain) {
+ /* We're searching a list of suffixes, this is the first answer, and it
+ * tells us that the name doesn't exist. Try the next one.
+ */
+
+ if (parent->expires > child->expires) parent->expires = child->expires;
+ adns__cancel_children(parent);
+ adns__free_interim(parent, pans->rrs.bytes);
+ pans->rrs.bytes = 0; pans->nrrs = 0;
+ adns__must_gettimeofday(ads, &now, &tvbuf);
+ if (now) adns__search_next(ads, parent, *now);
+ return;
+ }
+
+ if (cans->status && cans->status != adns_s_nodata)
+ { err = cans->status; goto x_err; }
+
+ assert(pans->rrsz == cans->rrsz);
+ err = append_addrs(parent, child, pans->rrsz,
+ &pans->rrs.addr, &pans->nrrs,
+ cans->rrs.addr, cans->nrrs);
+ if (err) goto x_err;
+
+ if (parent->children.head) LIST_LINK_TAIL(ads->childw, parent);
+ else if (!pans->nrrs) adns__query_fail(parent, adns_s_nodata);
+ else adns__query_done(parent);
+ parent->flags |= adns__qf_addr_answer;
+ return;
+
+x_err:
+ adns__query_fail(parent, err);
+}
+