X-Git-Url: https://git.distorted.org.uk/~mdw/adns/blobdiff_plain/da234f9fe6d3391530bcb1fe632f1164cf0ad9dc..4d6b3d18f00854d227660e42bd4006322673f420:/src/types.c

diff --git a/src/types.c b/src/types.c
index 4b2a526..d53fe3e 100644
--- a/src/types.c
+++ b/src/types.c
@@ -378,6 +378,27 @@ static unsigned addr_rrtypeflag(adns_rrtype type) {
   return i < addr_nrrtypes ? 1 << i : 0;
 }
 
+/* About CNAME handling in addr queries.
+ *
+ * A user-level addr query is translated into a number of protocol-level
+ * queries, and its job is to reassemble the results.  This gets tricky if
+ * the answers aren't consistent.  In particular, if the answers report
+ * inconsistent indirection via CNAME records (e.g., different CNAMEs, or
+ * some indirect via a CNAME, and some don't) then we have trouble.
+ *
+ * Once we've received an answer, even if it was NODATA, we set
+ * adns__qf_addr_answer on the parent query.  This will let us detect a
+ * conflict between a no-CNAME-with-NODATA reply and a subsequent CNAME.
+ *
+ * If we detect a conflict of any kind, then at least one answer came back
+ * with a CNAME record, so we pick the first such answer (somewhat
+ * arbitrarily) as being the `right' canonical name, and set this in the
+ * parent query's answer->cname slot.  We discard address records from the
+ * wrong name.  And finally we cancel the outstanding child queries, and
+ * resubmit address queries for the address families we don't yet have, with
+ * adns__qf_addr_cname set so that we know that we're in the fixup state.
+ */
+
 static adns_status pap_addr(const parseinfo *pai, int rrty, size_t rrsz,
 			    int *cbyte_io, int max, adns_rr_addr *storeto) {
   const byte *dgram= pai->dgram;
@@ -498,7 +519,26 @@ static unsigned addr_rrtypes(adns_state ads, adns_rrtype type,
   /* Return a mask of addr_rf_... flags indicating which address families are
    * wanted, given a query type and flags.
    */
-  return addr_rf_a;
+
+  adns_queryflags permitaf= 0;
+  unsigned want= 0;
+
+  if (!(type & adns__qtf_bigaddr))
+    qf= (qf & ~adns_qf_want_allaf) | adns_qf_want_ipv4;
+  else {
+    if (!(qf & adns_qf_want_allaf)) {
+      qf |= (type & adns__qtf_manyaf) ?
+	adns_qf_want_allaf : adns_qf_want_ipv4;
+    }
+    if (ads->iflags & adns_if_permit_ipv4) permitaf |= adns_qf_want_ipv4;
+    if (ads->iflags & adns_if_permit_ipv6) permitaf |= adns_qf_want_ipv6;
+    if (qf & permitaf) qf &= permitaf | ~adns_qf_want_allaf;
+  }
+
+  if (qf & adns_qf_want_ipv4) want |= addr_rf_a;
+  if (qf & adns_qf_want_ipv6) want |= addr_rf_aaaa;
+
+  return want;
 }
 
 static void icb_addr(adns_query parent, adns_query child);
@@ -520,13 +560,11 @@ static void addr_subqueries(adns_query qu, struct timeval now,
     err= adns__mkquery_frdgram(qu->ads, &qu->vb, &id, qd_dgram,qd_dglen,
 			       DNS_HDRSIZE, addr_all_rrtypes[i], qf);
     if (err) goto x_error;
-    err= adns__internal_submit(qu->ads, &cqu, &tinfo_addrsub,
+    err= adns__internal_submit(qu->ads, &cqu, qu, &tinfo_addrsub,
 			       addr_all_rrtypes[i] | qtf,
 			       &qu->vb, id, qf, now, &ctx);
     if (err) goto x_error;
     cqu->answer->rrsz= qu->answer->rrsz;
-    cqu->parent= qu;
-    LIST_LINK_TAIL_PART(qu->children, cqu,siblings.);
   }
   qu->state= query_childw;
   LIST_LINK_TAIL(qu->ads->childw, qu);
@@ -560,12 +598,10 @@ static adns_status addr_submit(adns_query parent, adns_query *query_r,
 
   ctx->tinfo.addr.want= want;
   ctx->tinfo.addr.have= 0;
-  err= adns__internal_submit(ads, &qu, adns__findtype(adns_r_addr),
+  err= adns__internal_submit(ads, &qu, parent, adns__findtype(adns_r_addr),
 			     type, qumsg_vb, id, flags, now, ctx);
   if (err) return err;
 
-  qu->parent= parent;
-  LIST_LINK_TAIL_PART(parent->children, qu, siblings.);
   *query_r= qu;
   return adns_s_ok;
 }
@@ -617,9 +653,55 @@ static void icb_addr(adns_query parent, adns_query child) {
   adns_answer *pans= parent->answer, *cans= child->answer;
   struct timeval now;
   adns_status err;
+  adns_queryflags qf;
+  int id;
 
   propagate_ttl(parent, child);
 
+  if (!(child->flags & adns__qf_addr_cname) &&
+      (parent->flags & adns__qf_addr_answer) &&
+      (!!pans->cname != !!cans->cname ||
+       (pans->cname && strcmp(pans->cname, cans->cname)))) {
+    /* 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;
+      parent->ctx.tinfo.addr.have= 0;
+      done_addr_type(parent, cans->type);
+      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), &tinfo_addrsub,
+		       adns_r_addr, parent->flags);
+    if (err) goto x_err;
+
+    /* Now cancel the remaining children, and try again with the CNAME we've
+     * settled on.
+     */
+    adns__cancel_children(parent);
+    if (gettimeofday(&now, 0)) goto x_gtod;
+    qf= adns__qf_addr_cname;
+    if (!(parent->flags & adns_qf_cname_loose)) qf |= adns_qf_cname_forbid;
+    addr_subqueries(parent, now, qf, child->vb.buf, child->vb.used);
+    return;
+  }
+
   if (cans->cname && !pans->cname) {
     err= copy_cname_from_child(parent, child);
     if (err) goto x_err;
@@ -652,6 +734,7 @@ static void icb_addr(adns_query parent, adns_query child) {
   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_gtod:
@@ -863,7 +946,8 @@ static adns_status pap_hostaddr(const parseinfo *pai, int *cbyte_io,
   ctx.callback= icb_hostaddr;
   ctx.pinfo.hostaddr= rrp;
   
-  nflags= adns_qf_quoteok_query | (pai->qu->flags & adns_qf_ipv6_mapv4);
+  nflags= adns_qf_quoteok_query | (pai->qu->flags & (adns_qf_want_allaf |
+						     adns_qf_ipv6_mapv4));
   if (!(pai->qu->flags & adns_qf_cname_loose)) nflags |= adns_qf_cname_forbid;
   
   st= addr_submit(pai->qu, &nqu, &pai->qu->vb, id, want,
@@ -1122,13 +1206,12 @@ static adns_status pa_ptr(const parseinfo *pai, int dmstart,
   ctx.callback= icb_ptr;
   memset(&ctx.pinfo,0,sizeof(ctx.pinfo));
   memset(&ctx.tinfo,0,sizeof(ctx.tinfo));
-  st= adns__internal_submit(pai->ads, &nqu, adns__findtype(rrtype),
+  st= adns__internal_submit(pai->ads, &nqu, pai->qu,
+			    adns__findtype(rrtype),
 			    rrtype, &pai->qu->vb, id,
 			    adns_qf_quoteok_query, pai->now, &ctx);
   if (st) return st;
 
-  nqu->parent= pai->qu;
-  LIST_LINK_TAIL_PART(pai->qu->children,nqu,siblings.);
   return adns_s_ok;
 }