From 413b26a719d402a30e61c8f93cf7cbf2f19375e3 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Sun, 17 May 2020 19:38:29 +0000
Subject:  Fix resolveq_aaaaa

 If s6dns_resolveq_aaaaa gets nodata on the AAAA query for a
qualified domain, it will now wait for the answer to the A query
on the same qualified domain before returning.

 Even if it gets nodata, it still means that the domain exists, so
it will not wait for results from other qualification attempts.
---
 src/libs6dns/s6dns_message_parse.c  |  4 ++-
 src/libs6dns/s6dns_resolveq.c       |  2 ++
 src/libs6dns/s6dns_resolveq_aaaaa.c | 50 ++++++++++++++++++++++---------------
 3 files changed, 35 insertions(+), 21 deletions(-)

(limited to 'src/libs6dns')

diff --git a/src/libs6dns/s6dns_message_parse.c b/src/libs6dns/s6dns_message_parse.c
index 06b7677..4aaee9a 100644
--- a/src/libs6dns/s6dns_message_parse.c
+++ b/src/libs6dns/s6dns_message_parse.c
@@ -10,6 +10,7 @@ int s6dns_message_parse (s6dns_message_header_t *h, char const *packet, unsigned
   s6dns_message_counts_t counts ;
   unsigned int pos ;
   unsigned int section ;
+  int gotans ;
   if (!s6dns_message_parse_init(h, &counts, packet, packetlen, &pos)) return 0 ;
   switch (h->rcode)
   {
@@ -21,6 +22,7 @@ int s6dns_message_parse (s6dns_message_header_t *h, char const *packet, unsigned
     case 5 : return (errno = ECONNREFUSED, 0) ;
     default: return (errno = EIO, 0) ;
   }
+  gotans = !!counts.an ;
   section = s6dns_message_parse_skipqd(&counts, packet, packetlen, &pos) ;
   while (section)
   {
@@ -33,5 +35,5 @@ int s6dns_message_parse (s6dns_message_header_t *h, char const *packet, unsigned
     }
     section = s6dns_message_parse_next(&counts, &rr, packet, packetlen, &pos) ;
   }
-  return 1 ;
+  return 1 + gotans ;
 }
diff --git a/src/libs6dns/s6dns_resolveq.c b/src/libs6dns/s6dns_resolveq.c
index a2933ee..3c1d22c 100644
--- a/src/libs6dns/s6dns_resolveq.c
+++ b/src/libs6dns/s6dns_resolveq.c
@@ -1,7 +1,9 @@
 /* ISC license. */
 
 #include <errno.h>
+
 #include <skalibs/error.h>
+
 #include <s6-dns/s6dns-domain.h>
 #include <s6-dns/s6dns-message.h>
 #include <s6-dns/s6dns-engine.h>
diff --git a/src/libs6dns/s6dns_resolveq_aaaaa.c b/src/libs6dns/s6dns_resolveq_aaaaa.c
index f990a7c..460956e 100644
--- a/src/libs6dns/s6dns_resolveq_aaaaa.c
+++ b/src/libs6dns/s6dns_resolveq_aaaaa.c
@@ -13,7 +13,19 @@
 #include <s6-dns/s6dns-engine.h>
 #include <s6-dns/s6dns-resolve.h>
 
-#define d_ip46full_from_ip(i, s, h) ((h) ? ip46full_from_ip6(i, s) : ip46full_from_ip4(i, s))
+static int addit (genalloc *ips, char const *s, size_t len, int is6)
+{
+  size_t base = genalloc_len(ip46full_t, ips) ;
+  size_t n = len >> (is6 ? 4 : 2) ;
+  ip46full_t *p ;
+  if (!genalloc_readyplus(ip46full_t, ips, n)) return 0 ;
+  p = genalloc_s(ip46full_t, ips) + base ;
+  for (size_t i = 0 ; i < n ; i++)
+    if (is6) ip46full_from_ip6(p + i, s + (i << 4)) ;
+    else ip46full_from_ip4(p + i, s + (i << 2)) ;
+  genalloc_setlen(ip46full_t, ips, base + n) ;
+  return 1 ;
+}
 
 int s6dns_resolveq_aaaaa_r (genalloc *ips, char const *name, size_t len, s6dns_rci_t const *rci, s6dns_debughook_t const *dbh, tain_t const *deadline, tain_t *stamp)
 {
@@ -22,6 +34,8 @@ int s6dns_resolveq_aaaaa_r (genalloc *ips, char const *name, size_t len, s6dns_r
   unsigned int best = 0 ;
   unsigned int n ;
   int e = 0 ;
+  int ans = 0 ;
+  int pinned = 0 ;
   unsigned int i = 0 ;
   {
     s6dns_domain_t domains[rci->rulesnum] ;
@@ -54,12 +68,19 @@ int s6dns_resolveq_aaaaa_r (genalloc *ips, char const *name, size_t len, s6dns_r
       {
         s6dns_message_header_t h ;
         int r ;
+        if (pinned && !(best & 1)) goto end ;
         if (best >= n << 1) goto notfound ;
         if (error_isagain(dtl[best].status)) break ;
         if (dtl[best].status) { errno = dtl[best].status ; goto err ; }
         r = s6dns_message_parse(&h, s6dns_engine_packet(dtl + best), s6dns_engine_packetlen(dtl + best), (best & 1) ? &s6dns_message_parse_answer_a : s6dns_message_parse_answer_aaaa, &data) ;
         if (r < 0) goto err ;
-        else if (r) goto found ;
+        else if (r)
+        {
+          if (!addit(ips, data.s, data.len, !(best & 1))) goto err ;
+          if (r > 1) ans |= 1 + !(best & 1) ;
+          data.len = 0 ;
+          pinned = 1 ;
+        }
         else switch (errno)
         {
           case EBUSY :
@@ -74,25 +95,14 @@ int s6dns_resolveq_aaaaa_r (genalloc *ips, char const *name, size_t len, s6dns_r
     }
   }
 
- found:
-  s6dns_engine_freen(dtl, n<<1) ;
-  {
-    size_t len = data.len >> ((best & 1) ? 2 : 4) ;
-    size_t i = 0 ;
-    size_t base = genalloc_len(ip46full_t, ips) ;
-    if (!genalloc_readyplus(ip46full_t, ips, len)) return -1 ;
-    for (; i < len ; i++)
-      d_ip46full_from_ip(genalloc_s(ip46full_t, ips) + base + i, data.s + (i << ((best & 1) ? 2 : 4)), !(best & 1)) ;
-    genalloc_setlen(ip46full_t, ips, base + len) ;
-  }
-  stralloc_free(&data) ;
-  return 1 ;
-
  notfound:
-  s6dns_engine_freen(dtl, n<<1) ;
-  return (errno = e, 0) ;
-
+  errno = e ;
+  ans = 0 ;
+  goto end ;
  err:
+  ans = -1 ;
+ end:
+  stralloc_free(&data) ;
   s6dns_engine_freen(dtl, n<<1) ;
-  return -1 ;
+  return ans ;
 }
-- 
cgit v1.2.3