From f4a6be2582b8dfe8adfa68da3dd8decf566b3983 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Fri, 1 Sep 2017 09:34:29 +0200
Subject: getaddrinfo: Fix error handling in gethosts [BZ #21915] [BZ #21922]

The old code uses errno as the primary indicator for success or
failure.  This is wrong because errno is only set for specific
combinations of the status return value and the h_errno variable.
---
 resolv/tst-resolv-basic.c | 78 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 55 insertions(+), 23 deletions(-)

(limited to 'resolv/tst-resolv-basic.c')

diff --git a/resolv/tst-resolv-basic.c b/resolv/tst-resolv-basic.c
index 64eedbbd81..66a0e8a165 100644
--- a/resolv/tst-resolv-basic.c
+++ b/resolv/tst-resolv-basic.c
@@ -50,7 +50,7 @@ response (const struct resolv_response_context *ctx,
     qname_compare = qname + 2;
   else
     qname_compare = qname;
-  enum {www, alias, nxdomain, long_name} requested_qname;
+  enum {www, alias, nxdomain, long_name, nodata} requested_qname;
   if (strcmp (qname_compare, "www.example") == 0)
     requested_qname = www;
   else if (strcmp (qname_compare, "alias.example") == 0)
@@ -59,6 +59,8 @@ response (const struct resolv_response_context *ctx,
     requested_qname = nxdomain;
   else if (strcmp (qname_compare, LONG_NAME) == 0)
     requested_qname = long_name;
+  else if (strcmp (qname_compare, "nodata.example") == 0)
+    requested_qname = nodata;
   else
     {
       support_record_failure ();
@@ -87,6 +89,8 @@ response (const struct resolv_response_context *ctx,
       resolv_response_close_record (b);
       resolv_response_open_record (b, "www.example", qclass, qtype, 0);
       break;
+    case nodata:
+      return;
     case nxdomain:
       FAIL_EXIT1 ("unreachable");
     }
@@ -267,6 +271,55 @@ test_bug_21295 (void)
     }
 }
 
+/* Run tests which do not expect any data.  */
+static void
+test_nodata_nxdomain (void)
+{
+  /* Iterate through different address families.  */
+  int families[] = { AF_UNSPEC, AF_INET, AF_INET6, -1 };
+  for (int i = 0; families[i] >= 0; ++i)
+    /* If do_tcp, prepend "t." to the name to trigger TCP
+       fallback.  */
+    for (int do_tcp = 0; do_tcp < 2; ++do_tcp)
+      /* If do_nxdomain, trigger an NXDOMAIN error (DNS failure),
+         otherwise use a NODATA response (empty but successful
+         answer).  */
+      for (int do_nxdomain = 0; do_nxdomain < 2; ++do_nxdomain)
+        {
+          int family = families[i];
+          char *name = xasprintf ("%s%s.example",
+                                  do_tcp ? "t." : "",
+                                  do_nxdomain ? "nxdomain" : "nodata");
+
+          if (family != AF_UNSPEC)
+            {
+              if (do_nxdomain)
+                check_h (name, family, "error: HOST_NOT_FOUND\n");
+              else
+                check_h (name, family, "error: NO_ADDRESS\n");
+            }
+
+          const char *expected;
+          if (do_nxdomain)
+            expected = "error: Name or service not known\n";
+          else
+            expected = "error: No address associated with hostname\n";
+
+          check_ai (name, "80", family, expected);
+
+          struct addrinfo hints =
+            {
+              .ai_family = family,
+              .ai_flags = AI_V4MAPPED | AI_ALL,
+            };
+          check_ai_hints (name, "80", hints, expected);
+          hints.ai_flags |= AI_CANONNAME;
+          check_ai_hints (name, "80", hints, expected);
+
+          free (name);
+        }
+}
+
 static int
 do_test (void)
 {
@@ -439,29 +492,8 @@ do_test (void)
             "address: DGRAM/UDP 2001:db8::4 80\n"
             "address: RAW/IP 2001:db8::4 80\n");
 
-  check_h ("nxdomain.example", AF_INET,
-           "error: HOST_NOT_FOUND\n");
-  check_h ("nxdomain.example", AF_INET6,
-           "error: HOST_NOT_FOUND\n");
-  check_ai ("nxdomain.example", "80", AF_UNSPEC,
-            "error: Name or service not known\n");
-  check_ai ("nxdomain.example", "80", AF_INET,
-            "error: Name or service not known\n");
-  check_ai ("nxdomain.example", "80", AF_INET6,
-            "error: Name or service not known\n");
-
-  check_h ("t.nxdomain.example", AF_INET,
-           "error: HOST_NOT_FOUND\n");
-  check_h ("t.nxdomain.example", AF_INET6,
-           "error: HOST_NOT_FOUND\n");
-  check_ai ("t.nxdomain.example", "80", AF_UNSPEC,
-            "error: Name or service not known\n");
-  check_ai ("t.nxdomain.example", "80", AF_INET,
-            "error: Name or service not known\n");
-  check_ai ("t.nxdomain.example", "80", AF_INET6,
-            "error: Name or service not known\n");
-
   test_bug_21295 ();
+  test_nodata_nxdomain ();
 
   resolv_test_end (aux);
 
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