resolv: Add beginnings of a libresolv test suite

7 files changed, 1542 insertions, 1 deletions

diff --git a/resolv/Makefile b/resolv/Makefile
index bd086e0e7d..5eb10e38af 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -39,7 +39,16 @@ extra-libs := libresolv libnss_dns
 ifeq ($(have-thread-library),yes)
 extra-libs += libanl
 routines += gai_sigqueue
-tests += tst-res_hconf_reorder
+
+tests += \
+  tst-bug18665 \
+  tst-bug18665-tcp \
+  tst-res_hconf_reorder \
+  tst-res_use_inet6 \
+  tst-resolv-basic \
+  tst-resolv-network \
+  tst-resolv-search \
+
 endif
 extra-libs-others = $(extra-libs)
 libresolv-routines := res_comp res_debug \
@@ -108,3 +117,10 @@ tst-leaks2-ENV = MALLOC_TRACE=$(objpfx)tst-leaks2.mtrace
 $(objpfx)mtrace-tst-leaks2.out: $(objpfx)tst-leaks2.out
 	$(common-objpfx)malloc/mtrace $(objpfx)tst-leaks2.mtrace > $@; \
 	$(evaluate-test)
+
+$(objpfx)tst-bug18665-tcp: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-bug18665: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-res_use_inet6: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-resolv-basic: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-resolv-network: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-resolv-search: $(objpfx)libresolv.so $(shared-thread-library)
diff --git a/resolv/tst-bug18665-tcp.c b/resolv/tst-bug18665-tcp.c
new file mode 100644
index 0000000000..fcd3bafdc0
--- /dev/null
+++ b/resolv/tst-bug18665-tcp.c
@@ -0,0 +1,229 @@
+/* Test __libc_res_nsend buffer mismanagement, basic TCP coverage.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <netdb.h>
+#include <resolv.h>
+#include <stdio.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/xthread.h>
+#include <support/xmemstream.h>
+
+static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+
+static int initial_address_count = 1;
+static int subsequent_address_count = 2000;
+static int response_number = 0;
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  TEST_VERIFY_EXIT (qname != NULL);
+
+  /* If not using TCP, just force its use.  */
+  if (!ctx->tcp)
+    {
+      struct resolv_response_flags flags = {.tc = true};
+      resolv_response_init (b, flags);
+      resolv_response_add_question (b, qname, qclass, qtype);
+      return;
+    }
+
+  struct resolv_response_flags flags = {};
+  resolv_response_init (b, flags);
+  resolv_response_add_question (b, qname, qclass, qtype);
+
+  resolv_response_section (b, ns_s_an);
+
+  /* The number of addresses (in the additional section) for the name
+     server record (in the authoritative section).  */
+  int address_count;
+  xpthread_mutex_lock (&lock);
+  ++response_number;
+  if (response_number == 1)
+    address_count = initial_address_count;
+  else if (response_number == 2)
+    {
+      address_count = 0;
+      resolv_response_drop (b);
+      resolv_response_close (b);
+    }
+  else
+    address_count = subsequent_address_count;
+  xpthread_mutex_unlock (&lock);
+
+  /* Only add the address record to the answer section if we requested
+     any name server addresses.  */
+  if (address_count > 0)
+    {
+      resolv_response_open_record (b, qname, qclass, qtype, 0);
+      switch (qtype)
+        {
+        case T_A:
+          {
+            char ipv4[4] = {10, response_number >> 8, response_number, 0};
+            ipv4[3] = 2 * ctx->tcp + 4 * ctx->server_index;
+            resolv_response_add_data (b, &ipv4, sizeof (ipv4));
+          }
+          break;
+        case T_AAAA:
+          {
+            char ipv6[16]
+              = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0,
+                 response_number >> 8, response_number, 0, 0};
+            ipv6[15] = 2 * ctx->tcp + 4 * ctx->server_index;
+            resolv_response_add_data (b, &ipv6, sizeof (ipv6));
+          }
+          break;
+        default:
+          support_record_failure ();
+          printf ("error: unexpected QTYPE: %s/%u/%u\n",
+                  qname, qclass, qtype);
+        }
+      resolv_response_close_record (b);
+
+      /* Add the name server record.  */
+      resolv_response_section (b, ns_s_ns);
+      resolv_response_open_record (b, "example", C_IN, T_NS, 0);
+      resolv_response_add_name (b, "ns.example");
+      resolv_response_close_record (b);
+
+      /* Increase the response size with name server addresses.  These
+         addresses are not copied out of nss_dns, and thus do not
+         trigger getaddrinfo retries with a larger buffer, making
+         testing more predictable.  */
+      resolv_response_section (b, ns_s_ar);
+      for (int i = 1; i <= address_count; ++i)
+        {
+          resolv_response_open_record (b, "ns.example", qclass, qtype, 0);
+          switch (qtype)
+            {
+            case T_A:
+              {
+                char ipv4[4] = {response_number, i >> 8, i, 0};
+                ipv4[3] = 2 * ctx->tcp + 4 * ctx->server_index;
+                resolv_response_add_data (b, &ipv4, sizeof (ipv4));
+              }
+              break;
+            case T_AAAA:
+              {
+                char ipv6[16]
+                  = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0,
+                     response_number >> 8, response_number,
+                     i >> 8, i, 0, 0};
+                ipv6[15] = 2 * ctx->tcp + 4 * ctx->server_index;
+                resolv_response_add_data (b, &ipv6, sizeof (ipv6));
+              }
+              break;
+            default:
+              support_record_failure ();
+              printf ("error: unexpected QTYPE: %s/%u/%u\n",
+                      qname, qclass, qtype);
+            }
+          resolv_response_close_record (b);
+        }
+    }
+}
+
+static char *
+expected_result (unsigned port, unsigned response_number)
+{
+  struct xmemstream mem;
+  xopen_memstream (&mem);
+  /* We fail the second TCP query to the first server by closing the
+     connection immediately, without returning any data.  This should
+     cause failover to the second server.  */
+  int server_index = 1;
+  fprintf (mem.out, "address: STREAM/TCP 10.%u.%u.%u %u\n",
+           (response_number >> 8) & 0xff, response_number & 0xff,
+           2 + 4 * server_index, port);
+  fprintf (mem.out, "address: STREAM/TCP 2001:db8::%x:%x %u\n",
+           (response_number + 1) & 0xffff,
+           2 + 4 * server_index, port);
+  xfclose_memstream (&mem);
+  return mem.buffer;
+}
+
+static void
+test_different_sizes (void)
+{
+  struct addrinfo hints =
+    {
+      .ai_family = AF_UNSPEC,
+      .ai_socktype = SOCK_STREAM,
+      .ai_protocol = IPPROTO_TCP,
+    };
+  struct addrinfo *ai;
+  char *expected;
+  int ret;
+
+  /* This magic number produces a response size close to 2048
+     bytes.  */
+  initial_address_count = 124;
+  response_number = 0;
+
+  ret = getaddrinfo ("www.example", "80", &hints, &ai);
+  expected = expected_result (80, 3);
+  check_addrinfo ("www.example:80", ai, ret, expected);
+  if (ret == 0)
+    freeaddrinfo (ai);
+  free (expected);
+
+  response_number = 0;
+  ret = getaddrinfo ("www123.example", "80", &hints, &ai);
+  if (ret == 0)
+    freeaddrinfo (ai);
+
+  response_number = 0;
+  ret = getaddrinfo ("www1234.example", "80", &hints, &ai);
+  if (ret == 0)
+    freeaddrinfo (ai);
+
+  response_number = 0;
+  ret = getaddrinfo ("www12345.example", "80", &hints, &ai);
+  if (ret == 0)
+    freeaddrinfo (ai);
+}
+
+static int
+do_test (void)
+{
+  struct resolv_test *obj = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response
+     });
+
+  test_different_sizes ();
+
+  _res.options |= RES_SNGLKUP;
+  test_different_sizes ();
+
+  _res.options |= RES_SNGLKUPREOP;
+  test_different_sizes ();
+
+  resolv_test_end (obj);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/resolv/tst-bug18665.c b/resolv/tst-bug18665.c
new file mode 100644
index 0000000000..2d0cdb2a96
--- /dev/null
+++ b/resolv/tst-bug18665.c
@@ -0,0 +1,138 @@
+/* Test for __libc_res_nsend buffer mismanagent (bug 18665), UDP case.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <netdb.h>
+#include <resolv.h>
+#include <stdio.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/resolv_test.h>
+#include <support/xthread.h>
+
+static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+
+static int initial_address_count;
+static int response_count;
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  TEST_VERIFY_EXIT (qname != NULL);
+  struct resolv_response_flags flags = {};
+  resolv_response_init (b, flags);
+  resolv_response_add_question (b, qname, qclass, qtype);
+
+  resolv_response_section (b, ns_s_an);
+
+  /* Add many A/AAAA records to the second response.  */
+  int address_count;
+  xpthread_mutex_lock (&lock);
+  if (response_count == 0)
+    address_count = initial_address_count;
+  else
+    address_count = 2000;
+  ++response_count;
+  xpthread_mutex_unlock (&lock);
+
+  for (int i = 0; i < address_count; ++i)
+    {
+      resolv_response_open_record (b, qname, qclass, qtype, 0);
+      switch (qtype)
+        {
+        case T_A:
+          {
+            char ipv4[4] = {10, i >> 8, i, 0};
+            ipv4[3] = 2 * ctx->tcp + 4 * ctx->server_index;
+            resolv_response_add_data (b, &ipv4, sizeof (ipv4));
+          }
+          break;
+        case T_AAAA:
+          {
+            char ipv6[16]
+              = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                 i >> 8, i, 0};
+            ipv6[15] = 2 * ctx->tcp + 4 * ctx->server_index;
+            resolv_response_add_data (b, &ipv6, sizeof (ipv6));
+          }
+          break;
+        default:
+          support_record_failure ();
+          printf ("error: unexpected QTYPE: %s/%u/%u\n",
+                  qname, qclass, qtype);
+        }
+      resolv_response_close_record (b);
+    }
+}
+
+static void
+test_different_sizes (void)
+{
+  struct addrinfo hints = { .ai_family = AF_UNSPEC, };
+  struct addrinfo *ai;
+  int ret;
+
+  /* This magic number produces a response size close to 2048
+     bytes.  */
+  initial_address_count = 126;
+  response_count = 0;
+
+  ret = getaddrinfo ("www.example", "80", &hints, &ai);
+  if (ret == 0)
+    freeaddrinfo (ai);
+
+  response_count = 0;
+  ret = getaddrinfo ("www123.example", "80", &hints, &ai);
+  if (ret == 0)
+    freeaddrinfo (ai);
+
+  response_count = 0;
+  ret = getaddrinfo ("www1234.example", "80", &hints, &ai);
+  if (ret == 0)
+    freeaddrinfo (ai);
+
+  response_count = 0;
+  ret = getaddrinfo ("www12345.example", "80", &hints, &ai);
+  if (ret == 0)
+    freeaddrinfo (ai);
+}
+
+static int
+do_test (void)
+{
+  struct resolv_test *obj = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response
+     });
+
+  test_different_sizes ();
+
+  _res.options |= RES_SNGLKUP;
+  test_different_sizes ();
+
+  _res.options |= RES_SNGLKUPREOP;
+  test_different_sizes ();
+
+  resolv_test_end (obj);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/resolv/tst-res_use_inet6.c b/resolv/tst-res_use_inet6.c
new file mode 100644
index 0000000000..5ed0ad0dc4
--- /dev/null
+++ b/resolv/tst-res_use_inet6.c
@@ -0,0 +1,201 @@
+/* Basic functionality tests for inet6 option processing.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <netdb.h>
+#include <resolv.h>
+#include <string.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/xthread.h>
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  bool include_both =  strcmp (qname, "both.example") == 0;
+  bool include_a = qtype == T_A || include_both;
+  bool include_aaaa = qtype == T_AAAA || include_both;
+
+  resolv_response_init (b, (struct resolv_response_flags) {});
+  resolv_response_add_question (b, qname, qclass, qtype);
+  resolv_response_section (b, ns_s_an);
+  if (include_a)
+    {
+      char ipv4[4] = {192, 0, 2, 17};
+      resolv_response_open_record (b, qname, qclass, T_A, 0);
+      resolv_response_add_data (b, &ipv4, sizeof (ipv4));
+      resolv_response_close_record (b);
+    }
+  if (include_aaaa)
+    {
+        char ipv6[16]
+          = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+        resolv_response_open_record (b, qname, qclass, T_AAAA, 0);
+        resolv_response_add_data (b, &ipv6, sizeof (ipv6));
+        resolv_response_close_record (b);
+    }
+}
+
+/* Test that getaddrinfo is not influenced by RES_USE_INET6.  */
+static void
+test_gai (void)
+{
+  {
+    struct addrinfo hints =
+      {
+        .ai_family = AF_UNSPEC,
+        .ai_socktype = SOCK_STREAM,
+        .ai_protocol = IPPROTO_TCP,
+      };
+    struct addrinfo *ai;
+    int ret = getaddrinfo ("www1.example", "80", &hints, &ai);
+    check_addrinfo ("getaddrinfo AF_UNSPEC www1.example", ai, ret,
+                    "address: STREAM/TCP 192.0.2.17 80\n"
+                    "address: STREAM/TCP 2001:db8::1 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+    ret = getaddrinfo ("both.example", "80", &hints, &ai);
+    /* Combined A/AAAA responses currently result in address
+       duplication.  */
+    check_addrinfo ("getaddrinfo AF_UNSPEC both.example", ai, ret,
+                    "address: STREAM/TCP 192.0.2.17 80\n"
+                    "address: STREAM/TCP 192.0.2.17 80\n"
+                    "address: STREAM/TCP 2001:db8::1 80\n"
+                    "address: STREAM/TCP 2001:db8::1 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+  }
+  {
+    struct addrinfo hints =
+      {
+        .ai_family = AF_INET,
+        .ai_socktype = SOCK_STREAM,
+        .ai_protocol = IPPROTO_TCP,
+      };
+    struct addrinfo *ai;
+    int ret = getaddrinfo ("www1.example", "80", &hints, &ai);
+    check_addrinfo ("getaddrinfo AF_INET www1.example", ai, ret,
+                    "address: STREAM/TCP 192.0.2.17 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+    ret = getaddrinfo ("both.example", "80", &hints, &ai);
+    check_addrinfo ("getaddrinfo AF_INET both.example", ai, ret,
+                    "address: STREAM/TCP 192.0.2.17 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+  }
+  {
+    struct addrinfo hints =
+      {
+        .ai_family = AF_INET6,
+        .ai_socktype = SOCK_STREAM,
+        .ai_protocol = IPPROTO_TCP,
+      };
+    struct addrinfo *ai;
+    int ret = getaddrinfo ("www1.example", "80", &hints, &ai);
+    check_addrinfo ("getaddrinfo (AF_INET6)", ai, ret,
+                    "address: STREAM/TCP 2001:db8::1 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+    ret = getaddrinfo ("both.example", "80", &hints, &ai);
+    check_addrinfo ("getaddrinfo AF_INET6 both.example", ai, ret,
+                    "address: STREAM/TCP 2001:db8::1 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+  }
+}
+
+/* Test that gethostbyname2 is not influenced by RES_USE_INET6.  */
+static void
+test_get2 (void)
+{
+  check_hostent ("gethostbyname2 AF_INET www1.example",
+                 gethostbyname2 ("www1.example", AF_INET),
+                 "name: www1.example\n"
+                 "address: 192.0.2.17\n");
+  check_hostent ("gethostbyname2 AF_INET both.example",
+                 gethostbyname2 ("both.example", AF_INET),
+                 "name: both.example\n"
+                 "address: 192.0.2.17\n");
+
+  check_hostent ("gethostbyname2 AF_INET6 www1.example",
+                 gethostbyname2 ("www1.example", AF_INET6),
+                 "name: www1.example\n"
+                 "address: 2001:db8::1\n");
+  check_hostent ("gethostbyname2 AF_INET6 both.example",
+                 gethostbyname2 ("both.example", AF_INET6),
+                 "name: both.example\n"
+                 "address: 2001:db8::1\n");
+}
+
+static void *
+threadfunc (void *ignored)
+{
+  struct resolv_test *obj = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response
+     });
+
+  check_hostent ("gethostbyname (\"www1.example\")",
+                 gethostbyname ("www1.example"),
+                 "name: www1.example\n"
+                 "address: 192.0.2.17\n");
+  check_hostent ("gethostbyname (\"both.example\")",
+                 gethostbyname ("both.example"),
+                 "name: both.example\n"
+                 "address: 192.0.2.17\n");
+  test_get2 ();
+  test_gai ();
+
+  _res.options |= RES_USE_INET6;
+  check_hostent ("gethostbyname (\"www1.example\")",
+                 gethostbyname ("www1.example"),
+                 "name: www1.example\n"
+                 "address: 2001:db8::1\n");
+  check_hostent ("gethostbyname (\"both.example\")",
+                 gethostbyname ("both.example"),
+                 "name: both.example\n"
+                 "address: 2001:db8::1\n");
+  test_get2 ();
+  test_gai ();
+
+  resolv_test_end (obj);
+
+  return NULL;
+}
+
+static int
+do_test (void)
+{
+  resolv_test_init ();
+
+  /* Attempt to run on a non-main thread first.  */
+  {
+    pthread_t thr = xpthread_create (NULL, threadfunc, NULL);
+    xpthread_join (thr);
+  }
+
+  /* Try the main thread next.  */
+  threadfunc (NULL);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/resolv/tst-resolv-basic.c b/resolv/tst-resolv-basic.c
new file mode 100644
index 0000000000..78c581df1d
--- /dev/null
+++ b/resolv/tst-resolv-basic.c
@@ -0,0 +1,315 @@
+/* Test basic nss_dns functionality and the resolver test harness itself.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/support.h>
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  TEST_VERIFY_EXIT (qname != NULL);
+
+  /* The "t." prefix can be used to request TCP fallback.  */
+  bool force_tcp;
+  if (strncmp ("t.", qname, 2) == 0)
+    force_tcp = true;
+  else
+    force_tcp = false;
+  const char *qname_compare;
+  if (force_tcp)
+    qname_compare = qname + 2;
+  else
+    qname_compare = qname;
+  enum {www, alias, nxdomain} requested_qname;
+  if (strcmp (qname_compare, "www.example") == 0)
+    requested_qname = www;
+  else if (strcmp (qname_compare, "alias.example") == 0)
+    requested_qname = alias;
+  else if (strcmp (qname_compare, "nxdomain.example") == 0)
+    requested_qname = nxdomain;
+  else
+    {
+      support_record_failure ();
+      printf ("error: unexpected QNAME: %s\n", qname);
+      return;
+    }
+  TEST_VERIFY_EXIT (qclass == C_IN);
+  struct resolv_response_flags flags = {.tc = force_tcp && !ctx->tcp};
+  if (requested_qname == nxdomain)
+    flags.rcode = 3;            /* NXDOMAIN */
+  resolv_response_init (b, flags);
+  resolv_response_add_question (b, qname, qclass, qtype);
+  if (requested_qname == nxdomain || flags.tc)
+    return;
+
+  resolv_response_section (b, ns_s_an);
+  switch (requested_qname)
+    {
+    case www:
+      resolv_response_open_record (b, qname, qclass, qtype, 0);
+      break;
+    case alias:
+      resolv_response_open_record (b, qname, qclass, T_CNAME, 0);
+      resolv_response_add_name (b, "www.example");
+      resolv_response_close_record (b);
+      resolv_response_open_record (b, "www.example", qclass, qtype, 0);
+      break;
+    case nxdomain:
+      FAIL_EXIT1 ("unreachable");
+    }
+  switch (qtype)
+    {
+    case T_A:
+      {
+        char ipv4[4] = {192, 0, 2, 17};
+        ipv4[3] += requested_qname + 2 * ctx->tcp + 4 * ctx->server_index;
+        resolv_response_add_data (b, &ipv4, sizeof (ipv4));
+      }
+      break;
+    case T_AAAA:
+      {
+        char ipv6[16]
+          = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+        ipv6[15] += requested_qname + 2 * ctx->tcp + 4 * ctx->server_index;
+        resolv_response_add_data (b, &ipv6, sizeof (ipv6));
+      }
+      break;
+    default:
+      support_record_failure ();
+      printf ("error: unexpected QTYPE: %s/%u/%u\n",
+              qname, qclass, qtype);
+    }
+  resolv_response_close_record (b);
+}
+
+static void
+check_h (const char *name, int family, const char *expected)
+{
+  if (family == AF_INET)
+    {
+      char *query = xasprintf ("gethostbyname (\"%s\")", name);
+      check_hostent (query, gethostbyname (name), expected);
+      free (query);
+    }
+  {
+    char *query = xasprintf ("gethostbyname2 (\"%s\", %d)", name, family);
+    check_hostent (query, gethostbyname2 (name, family), expected);
+    free (query);
+  }
+
+  bool too_small = true;
+  for (unsigned int offset = 0; offset < 8; ++offset)
+    for (unsigned int size = 1; too_small; ++size)
+      {
+        char *buf = xmalloc (offset + size);
+        too_small = false;
+
+        struct hostent hostbuf;
+        struct hostent *result;
+        int herror;
+        if (family == AF_INET)
+          {
+            char *query = xasprintf ("gethostbyname (\"%s\") %u/%u",
+                                     name, offset, size);
+            int ret = gethostbyname_r
+              (name, &hostbuf, buf + offset, size, &result, &herror);
+            if (ret == 0)
+              {
+                h_errno = herror;
+                check_hostent (query, result, expected);
+              }
+            else if (ret == ERANGE)
+              too_small = true;
+            else
+              {
+                errno = ret;
+                FAIL_EXIT1 ("gethostbyname_r: %m");
+              }
+            free (query);
+            memset (buf, 0, offset + size);
+          }
+        char *query = xasprintf ("gethostbyname2 (\"%s\", %d) %u/%u",
+                                 name, family, offset, size);
+        int ret = gethostbyname2_r
+          (name, family, &hostbuf, buf + offset, size, &result, &herror);
+        if (ret == 0)
+          {
+            h_errno = herror;
+            check_hostent (query, result, expected);
+          }
+        else if (ret == ERANGE)
+          too_small = true;
+        else
+          {
+            errno = ret;
+            FAIL_EXIT1 ("gethostbyname_r: %m");
+          }
+        free (buf);
+        free (query);
+      }
+}
+
+static void
+check_ai (const char *name, const char *service,
+          int family, const char *expected)
+{
+  struct addrinfo hints = {.ai_family = family};
+  struct addrinfo *ai;
+  char *query = xasprintf ("%s:%s [%d]", name, service, family);
+  int ret = getaddrinfo (name, service, &hints, &ai);
+  check_addrinfo (query, ai, ret, expected);
+  if (ret == 0)
+    freeaddrinfo (ai);
+  free (query);
+}
+
+static int
+do_test (void)
+{
+  struct resolv_test *aux = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response,
+     });
+
+  check_h ("www.example", AF_INET,
+           "name: www.example\n"
+           "address: 192.0.2.17\n");
+  check_h ("alias.example", AF_INET,
+           "name: www.example\n"
+           "alias: alias.example\n"
+           "address: 192.0.2.18\n");
+  check_h ("www.example", AF_INET6,
+           "name: www.example\n"
+           "address: 2001:db8::1\n");
+  check_h ("alias.example", AF_INET6,
+           "name: www.example\n"
+           "alias: alias.example\n"
+           "address: 2001:db8::2\n");
+  check_ai ("www.example", "80", AF_UNSPEC,
+            "address: STREAM/TCP 192.0.2.17 80\n"
+            "address: DGRAM/UDP 192.0.2.17 80\n"
+            "address: RAW/IP 192.0.2.17 80\n"
+            "address: STREAM/TCP 2001:db8::1 80\n"
+            "address: DGRAM/UDP 2001:db8::1 80\n"
+            "address: RAW/IP 2001:db8::1 80\n");
+  check_ai ("alias.example", "80", AF_UNSPEC,
+            "address: STREAM/TCP 192.0.2.18 80\n"
+            "address: DGRAM/UDP 192.0.2.18 80\n"
+            "address: RAW/IP 192.0.2.18 80\n"
+            "address: STREAM/TCP 2001:db8::2 80\n"
+            "address: DGRAM/UDP 2001:db8::2 80\n"
+            "address: RAW/IP 2001:db8::2 80\n");
+  check_ai ("www.example", "80", AF_INET,
+            "address: STREAM/TCP 192.0.2.17 80\n"
+            "address: DGRAM/UDP 192.0.2.17 80\n"
+            "address: RAW/IP 192.0.2.17 80\n");
+  check_ai ("alias.example", "80", AF_INET,
+            "address: STREAM/TCP 192.0.2.18 80\n"
+            "address: DGRAM/UDP 192.0.2.18 80\n"
+            "address: RAW/IP 192.0.2.18 80\n");
+  check_ai ("www.example", "80", AF_INET6,
+            "address: STREAM/TCP 2001:db8::1 80\n"
+            "address: DGRAM/UDP 2001:db8::1 80\n"
+            "address: RAW/IP 2001:db8::1 80\n");
+  check_ai ("alias.example", "80", AF_INET6,
+            "address: STREAM/TCP 2001:db8::2 80\n"
+            "address: DGRAM/UDP 2001:db8::2 80\n"
+            "address: RAW/IP 2001:db8::2 80\n");
+
+  check_h ("t.www.example", AF_INET,
+           "name: t.www.example\n"
+           "address: 192.0.2.19\n");
+  check_h ("t.alias.example", AF_INET,
+           "name: www.example\n"
+           "alias: t.alias.example\n"
+           "address: 192.0.2.20\n");
+  check_h ("t.www.example", AF_INET6,
+           "name: t.www.example\n"
+           "address: 2001:db8::3\n");
+  check_h ("t.alias.example", AF_INET6,
+           "name: www.example\n"
+           "alias: t.alias.example\n"
+           "address: 2001:db8::4\n");
+  check_ai ("t.www.example", "80", AF_UNSPEC,
+            "address: STREAM/TCP 192.0.2.19 80\n"
+            "address: DGRAM/UDP 192.0.2.19 80\n"
+            "address: RAW/IP 192.0.2.19 80\n"
+            "address: STREAM/TCP 2001:db8::3 80\n"
+            "address: DGRAM/UDP 2001:db8::3 80\n"
+            "address: RAW/IP 2001:db8::3 80\n");
+  check_ai ("t.alias.example", "80", AF_UNSPEC,
+            "address: STREAM/TCP 192.0.2.20 80\n"
+            "address: DGRAM/UDP 192.0.2.20 80\n"
+            "address: RAW/IP 192.0.2.20 80\n"
+            "address: STREAM/TCP 2001:db8::4 80\n"
+            "address: DGRAM/UDP 2001:db8::4 80\n"
+            "address: RAW/IP 2001:db8::4 80\n");
+  check_ai ("t.www.example", "80", AF_INET,
+            "address: STREAM/TCP 192.0.2.19 80\n"
+            "address: DGRAM/UDP 192.0.2.19 80\n"
+            "address: RAW/IP 192.0.2.19 80\n");
+  check_ai ("t.alias.example", "80", AF_INET,
+            "address: STREAM/TCP 192.0.2.20 80\n"
+            "address: DGRAM/UDP 192.0.2.20 80\n"
+            "address: RAW/IP 192.0.2.20 80\n");
+  check_ai ("t.www.example", "80", AF_INET6,
+            "address: STREAM/TCP 2001:db8::3 80\n"
+            "address: DGRAM/UDP 2001:db8::3 80\n"
+            "address: RAW/IP 2001:db8::3 80\n");
+  check_ai ("t.alias.example", "80", AF_INET6,
+            "address: STREAM/TCP 2001:db8::4 80\n"
+            "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");
+
+  resolv_test_end (aux);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/resolv/tst-resolv-network.c b/resolv/tst-resolv-network.c
new file mode 100644
index 0000000000..f2485277be
--- /dev/null
+++ b/resolv/tst-resolv-network.c
@@ -0,0 +1,299 @@
+/* Test getnetbyname and getnetbyaddr.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <netdb.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/support.h>
+#include <support/xmemstream.h>
+
+static void
+send_ptr (struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype,
+          const char *alias)
+{
+  resolv_response_init (b, (struct resolv_response_flags) {});
+  resolv_response_add_question (b, qname, qclass, qtype);
+  resolv_response_section (b, ns_s_an);
+  resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+  resolv_response_add_name (b, alias);
+  resolv_response_close_record (b);
+}
+
+static void
+handle_code (const struct resolv_response_context *ctx,
+             struct resolv_response_builder *b,
+             const char *qname, uint16_t qclass, uint16_t qtype,
+             int code)
+{
+  switch (code)
+    {
+    case 1:
+      send_ptr (b, qname, qclass, qtype, "1.in-addr.arpa");
+      break;
+    case 2:
+      send_ptr (b, qname, qclass, qtype, "2.1.in-addr.arpa");
+      break;
+    case 3:
+      send_ptr (b, qname, qclass, qtype, "3.2.1.in-addr.arpa");
+      break;
+    case 4:
+      send_ptr (b, qname, qclass, qtype, "4.3.2.1.in-addr.arpa");
+      break;
+    case 5:
+      /* Test multiple PTR records.  */
+      resolv_response_init (b, (struct resolv_response_flags) {});
+      resolv_response_add_question (b, qname, qclass, qtype);
+      resolv_response_section (b, ns_s_an);
+      resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+      resolv_response_add_name (b, "127.in-addr.arpa");
+      resolv_response_close_record (b);
+      resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+      resolv_response_add_name (b, "0.in-addr.arpa");
+      resolv_response_close_record (b);
+      break;
+    case 6:
+      /* Test skipping of RRSIG record.  */
+      resolv_response_init (b, (struct resolv_response_flags) { });
+      resolv_response_add_question (b, qname, qclass, qtype);
+      resolv_response_section (b, ns_s_an);
+
+      resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+      resolv_response_add_name (b, "127.in-addr.arpa");
+      resolv_response_close_record (b);
+
+      resolv_response_open_record (b, qname, qclass, 46 /* RRSIG */, 0);
+      {
+        char buf[500];
+        memset (buf, 0x3f, sizeof (buf));
+        resolv_response_add_data (b, buf, sizeof (buf));
+      }
+      resolv_response_close_record (b);
+
+      resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+      resolv_response_add_name (b, "0.in-addr.arpa");
+      resolv_response_close_record (b);
+      break;
+    case 7:
+      /* Test CNAME handling.  */
+      resolv_response_init (b, (struct resolv_response_flags) { });
+      resolv_response_add_question (b, qname, qclass, qtype);
+      resolv_response_section (b, ns_s_an);
+      resolv_response_open_record (b, qname, qclass, T_CNAME, 0);
+      resolv_response_add_name (b, "cname.example");
+      resolv_response_close_record (b);
+      resolv_response_open_record (b, "cname.example", qclass, T_PTR, 0);
+      resolv_response_add_name (b, "4.3.2.1.in-addr.arpa");
+      resolv_response_close_record (b);
+      break;
+
+    case 100:
+      resolv_response_init (b, (struct resolv_response_flags) { .rcode = 0, });
+      resolv_response_add_question (b, qname, qclass, qtype);
+      break;
+    case 101:
+      resolv_response_init (b, (struct resolv_response_flags)
+                            { .rcode = NXDOMAIN, });
+      resolv_response_add_question (b, qname, qclass, qtype);
+      break;
+    case 102:
+      resolv_response_init (b, (struct resolv_response_flags) {.rcode = SERVFAIL});
+      resolv_response_add_question (b, qname, qclass, qtype);
+      break;
+    case 103:
+      /* Check response length matching.  */
+      if (!ctx->tcp)
+        {
+          resolv_response_init (b, (struct resolv_response_flags) {.tc = true});
+          resolv_response_add_question (b, qname, qclass, qtype);
+        }
+      else
+        {
+          resolv_response_init (b, (struct resolv_response_flags) {.ancount = 1});
+          resolv_response_add_question (b, qname, qclass, qtype);
+          resolv_response_section (b, ns_s_an);
+          resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+          resolv_response_add_name (b, "127.in-addr.arpa");
+          resolv_response_close_record (b);
+          resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+          resolv_response_add_name (b, "example");
+          resolv_response_close_record (b);
+
+          resolv_response_open_record (b, qname, qclass, T_PTR, 0);
+          size_t to_fill = 65535 - resolv_response_length (b)
+            - 2 /* length, "n" */ - 2 /* compression reference */
+            - 2 /* RR type */;
+          for (size_t i = 0; i < to_fill; ++i)
+            resolv_response_add_data (b, "", 1);
+          resolv_response_close_record (b);
+          resolv_response_add_name (b, "n.example");
+          uint16_t rrtype = htons (T_PTR);
+          resolv_response_add_data (b, &rrtype, sizeof (rrtype));
+        }
+      break;
+    default:
+      FAIL_EXIT1 ("invalid QNAME: %s (code %d)", qname, code);
+    }
+}
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  int code;
+  if (strstr (qname, "in-addr.arpa") == NULL)
+    {
+      char *tail;
+      if (sscanf (qname, "code%d.%ms", &code, &tail) != 2
+          || strcmp (tail, "example") != 0)
+        FAIL_EXIT1 ("invalid QNAME: %s", qname);
+      free (tail);
+      handle_code (ctx, b, qname, qclass, qtype, code);
+    }
+  else
+    {
+      /* Reverse lookup.  */
+      int components[4];
+      char *tail;
+      if (sscanf (qname, "%d.%d.%d.%d.%ms",
+                  components, components + 1, components + 2, components + 3,
+                  &tail) != 5
+          || strcmp (tail, "in-addr.arpa") != 0)
+        FAIL_EXIT1 ("invalid QNAME: %s", qname);
+      free (tail);
+      handle_code (ctx, b, qname, qclass, qtype, components[3]);
+    }
+}
+
+static void
+check_reverse (int code, const char *expected)
+{
+  char *query = xasprintf ("code=%d", code);
+  check_netent (query, getnetbyaddr (code, AF_INET), expected);
+  free (query);
+}
+
+/* Test for CVE-2016-3075.  */
+static void
+check_long_name (void)
+{
+  struct xmemstream mem;
+  xopen_memstream (&mem);
+
+  char label[65];
+  memset (label, 'x', 63);
+  label[63] = '.';
+  label[64] = '\0';
+  for (unsigned i = 0; i < 64 * 1024 * 1024 / strlen (label); ++i)
+    fprintf (mem.out, "%s", label);
+
+  xfclose_memstream (&mem);
+
+  check_netent ("long name", getnetbyname (mem.buffer),
+                "error: NO_RECOVERY\n");
+
+  free (mem.buffer);
+}
+
+int
+main (void)
+{
+  struct resolv_test *obj = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response
+     });
+
+  /* Lookup by name, success cases.  */
+  check_netent ("code1.example", getnetbyname ("code1.example"),
+                "alias: 1.in-addr.arpa\n"
+                "net: 0x00000001\n");
+  check_netent ("code2.example", getnetbyname ("code2.example"),
+                "alias: 2.1.in-addr.arpa\n"
+                "net: 0x00000102\n");
+  check_netent ("code3.example", getnetbyname ("code3.example"),
+                "alias: 3.2.1.in-addr.arpa\n"
+                "net: 0x00010203\n");
+  check_netent ("code4.example", getnetbyname ("code4.example"),
+                "alias: 4.3.2.1.in-addr.arpa\n"
+                "net: 0x01020304\n");
+  check_netent ("code5.example", getnetbyname ("code5.example"),
+                "alias: 127.in-addr.arpa\n"
+                "alias: 0.in-addr.arpa\n"
+                "net: 0x0000007f\n");
+  check_netent ("code6.example", getnetbyname ("code6.example"),
+                "alias: 127.in-addr.arpa\n"
+                "alias: 0.in-addr.arpa\n"
+                "net: 0x0000007f\n");
+  check_netent ("code7.example", getnetbyname ("code7.example"),
+                "alias: 4.3.2.1.in-addr.arpa\n"
+                "net: 0x01020304\n");
+
+  /* Lookup by name, failure cases.  */
+  check_netent ("code100.example", getnetbyname ("code100.example"),
+                "error: NO_ADDRESS\n");
+  check_netent ("code101.example", getnetbyname ("code101.example"),
+                "error: HOST_NOT_FOUND\n");
+  check_netent ("code102.example", getnetbyname ("code102.example"),
+                "error: TRY_AGAIN\n");
+  check_netent ("code103.example", getnetbyname ("code103.example"),
+                "error: NO_RECOVERY\n");
+
+  /* Lookup by address, success cases.  */
+  check_reverse (1,
+                 "name: 1.in-addr.arpa\n"
+                 "net: 0x00000001\n");
+  check_reverse (2,
+                 "name: 2.1.in-addr.arpa\n"
+                 "net: 0x00000002\n");
+  check_reverse (3,
+                 "name: 3.2.1.in-addr.arpa\n"
+                 "net: 0x00000003\n");
+  check_reverse (4,
+                 "name: 4.3.2.1.in-addr.arpa\n"
+                 "net: 0x00000004\n");
+  check_reverse (5,
+                 "name: 127.in-addr.arpa\n"
+                 "alias: 0.in-addr.arpa\n"
+                 "net: 0x00000005\n");
+  check_reverse (6,
+                 "name: 127.in-addr.arpa\n"
+                 "alias: 0.in-addr.arpa\n"
+                 "net: 0x00000006\n");
+  check_reverse (7,
+                 "name: 4.3.2.1.in-addr.arpa\n"
+                 "net: 0x00000007\n");
+
+  /* Lookup by address, failure cases.  */
+  check_reverse (100,
+                 "error: NO_ADDRESS\n");
+  check_reverse (101,
+                 "error: HOST_NOT_FOUND\n");
+  check_reverse (102,
+                 "error: TRY_AGAIN\n");
+  check_reverse (103,
+                 "error: NO_RECOVERY\n");
+
+  check_long_name ();
+
+  resolv_test_end (obj);
+}
diff --git a/resolv/tst-resolv-search.c b/resolv/tst-resolv-search.c
new file mode 100644
index 0000000000..d95f9d9601
--- /dev/null
+++ b/resolv/tst-resolv-search.c
@@ -0,0 +1,343 @@
+/* Test search/default domain name behavior.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <resolv.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/support.h>
+#include <support/xmemstream.h>
+
+struct item
+{
+  const char *name;
+  int response;
+};
+
+const struct item items[] =
+  {
+    {"hostname.usersys.example.com", 1},
+    {"hostname.corp.example.com", 1},
+    {"hostname.example.com", 1},
+
+    {"mail.corp.example.com", 1},
+    {"mail.example.com", 1},
+
+    {"file.corp.example.com", 2},
+    {"file.corp", 1},
+    {"file.example.com", 1},
+    {"servfail-usersys.usersys.example.com", -ns_r_servfail},
+    {"servfail-usersys.corp.example.com", 1},
+    {"servfail-usersys.example.com", 1},
+    {"servfail-corp.usersys.example.com", 1},
+    {"servfail-corp.corp.example.com", -ns_r_servfail},
+    {"servfail-corp.example.com", 1},
+    {"www.example.com", 1},
+    {"large.example.com", 200},
+
+    /* Test query amplification with a SERVFAIL response combined with
+       a large RRset.  */
+    {"large-servfail.usersys.example.com", -ns_r_servfail},
+    {"large-servfail.example.com", 2000},
+    {}
+  };
+
+enum
+  {
+    name_not_found = -1,
+    name_no_data = -2
+  };
+
+static int
+find_name (const char *name)
+{
+  for (int i = 0; items[i].name != NULL; ++i)
+    {
+      if (strcmp (name, items[i].name) == 0)
+        return i;
+    }
+  if (strcmp (name, "example.com") == 0
+      || strcmp (name, "usersys.example.com") == 0
+      || strcmp (name, "corp.example.com") == 0)
+    return name_no_data;
+  return name_not_found;
+}
+
+static int rcode_override_server_index = -1;
+static int rcode_override;
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  if (ctx->server_index == rcode_override_server_index)
+    {
+      struct resolv_response_flags flags = {.rcode = rcode_override};
+      resolv_response_init (b, flags);
+      resolv_response_add_question (b, qname, qclass, qtype);
+      return;
+    }
+
+  int index = find_name (qname);
+  struct resolv_response_flags flags = {};
+  if (index == name_not_found)
+    flags.rcode = ns_r_nxdomain;
+  else if (index >= 0 && items[index].response < 0)
+    flags.rcode = -items[index].response;
+  else if (index >= 0 && items[index].response > 5 && !ctx->tcp)
+    /* Force TCP if more than 5 addresses where requested.  */
+    flags.tc = true;
+  resolv_response_init (b, flags);
+  resolv_response_add_question (b, qname, qclass, qtype);
+
+  if (flags.tc || index < 0 || items[index].response < 0)
+    return;
+
+  resolv_response_section (b, ns_s_an);
+
+  for (int i = 0; i < items[index].response; ++i)
+    {
+      resolv_response_open_record (b, qname, qclass, qtype, 0);
+
+      switch (qtype)
+        {
+        case T_A:
+          {
+            char addr[4] = {10, index, i >> 8, i};
+            resolv_response_add_data (b, addr, sizeof (addr));
+          }
+          break;
+        case T_AAAA:
+          {
+            char addr[16]
+              = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0,
+                 0, index + 1, (i + 1) >> 8, i + 1};
+            resolv_response_add_data (b, addr, sizeof (addr));
+          }
+          break;
+        default:
+          support_record_failure ();
+          printf ("error: unexpected QTYPE: %s/%u/%u\n",
+                  qname, qclass, qtype);
+        }
+      resolv_response_close_record (b);
+    }
+}
+
+enum output_format
+  {
+    format_get, format_gai
+  };
+
+static void
+format_expected_1 (FILE *out, int family, enum output_format format, int index)
+{
+  for (int i = 0; i < items[index].response; ++i)
+    {
+      char address[200];
+      switch (family)
+        {
+        case AF_INET:
+          snprintf (address, sizeof (address), "10.%d.%d.%d",
+                    index, (i >> 8) & 0xff, i & 0xff);
+          break;
+        case AF_INET6:
+          snprintf (address, sizeof (address), "2001:db8::%x:%x",
+                    index + 1, i + 1);
+          break;
+        default:
+          FAIL_EXIT1 ("unreachable");
+        }
+
+      switch (format)
+        {
+        case format_get:
+          fprintf (out, "address: %s\n", address);
+          break;
+        case format_gai:
+          fprintf (out, "address: STREAM/TCP %s 80\n", address);
+        }
+    }
+}
+
+static char *
+format_expected (const char *fqdn, int family, enum output_format format)
+{
+  int index = find_name (fqdn);
+  TEST_VERIFY_EXIT (index >= 0);
+  struct xmemstream stream;
+  xopen_memstream (&stream);
+
+  TEST_VERIFY_EXIT (items[index].response >= 0);
+  if (format == format_get)
+    fprintf (stream.out, "name: %s\n", items[index].name);
+  if (family == AF_INET || family == AF_UNSPEC)
+    format_expected_1 (stream.out, AF_INET, format, index);
+  if (family == AF_INET6 || family == AF_UNSPEC)
+    format_expected_1 (stream.out, AF_INET6, format, index);
+
+  xfclose_memstream (&stream);
+  return stream.buffer;
+}
+
+static void
+do_get (const char *name, const char *fqdn, int family)
+{
+  char *expected = format_expected (fqdn, family, format_get);
+  if (family == AF_INET)
+    {
+      char *query = xasprintf ("gethostbyname (\"%s\")", name);
+      check_hostent (query, gethostbyname (name), expected);
+      free (query);
+    }
+  char *query = xasprintf ("gethostbyname2 (\"%s\", %d)", name, family);
+  check_hostent (query, gethostbyname2 (name, family), expected);
+
+  /* Test res_search.  */
+  int qtype;
+  switch (family)
+    {
+    case AF_INET:
+      qtype = T_A;
+      break;
+    case AF_INET6:
+      qtype = T_AAAA;
+      break;
+    default:
+      qtype = -1;
+    }
+  if (qtype >= 0)
+    {
+      int sz = 512;
+      unsigned char *response = xmalloc (sz);
+      int ret = res_search (name, C_IN, qtype, response, sz);
+      TEST_VERIFY_EXIT (ret >= 0);
+      if (ret > sz)
+        {
+          /* Truncation.  Retry with a larger buffer.  */
+          sz = 65535;
+          unsigned char *newptr = xrealloc (response, sz);
+          response = newptr;
+
+          ret = res_search (name, C_IN, qtype, response, sz);
+          TEST_VERIFY_EXIT (ret >= 0);
+          TEST_VERIFY_EXIT (ret < sz);
+        }
+      check_dns_packet (query, response, ret, expected);
+      free (response);
+    }
+
+  free (query);
+  free (expected);
+}
+
+static void
+do_gai (const char *name, const char *fqdn, int family)
+{
+  struct addrinfo hints =
+    {
+      .ai_family = family,
+      .ai_protocol = IPPROTO_TCP,
+      .ai_socktype = SOCK_STREAM
+    };
+  struct addrinfo *ai;
+  char *query = xasprintf ("%s:80 [%d]", name, family);
+  int ret = getaddrinfo (name, "80", &hints, &ai);
+  char *expected = format_expected (fqdn, family, format_gai);
+  check_addrinfo (query, ai, ret, expected);
+  if (ret == 0)
+    freeaddrinfo (ai);
+  free (expected);
+  free (query);
+}
+
+static void
+do_both (const char *name, const char *fqdn)
+{
+  do_get (name, fqdn, AF_INET);
+  do_get (name, fqdn, AF_INET6);
+  do_gai (name, fqdn, AF_INET);
+  do_gai (name, fqdn, AF_INET6);
+  do_gai (name, fqdn, AF_UNSPEC);
+}
+
+static void
+do_test_all (bool unconnectable_server)
+{
+  struct resolv_redirect_config config =
+    {
+      .response_callback = response,
+      .search = {"usersys.example.com", "corp.example.com", "example.com"},
+    };
+  struct resolv_test *obj = resolv_test_start (config);
+
+  if (unconnectable_server)
+    {
+      /* 255.255.255.255 results in an immediate connect failure.  The
+         next server will supply the answer instead.  This is a
+         triggering condition for bug 19791.  */
+      _res.nsaddr_list[0].sin_addr.s_addr = -1;
+      _res.nsaddr_list[0].sin_port = htons (53);
+    }
+
+  do_both ("file", "file.corp.example.com");
+  do_both ("www", "www.example.com");
+  do_both ("servfail-usersys", "servfail-usersys.corp.example.com");
+  do_both ("servfail-corp", "servfail-corp.usersys.example.com");
+  do_both ("large", "large.example.com");
+  do_both ("large-servfail", "large-servfail.example.com");
+  do_both ("file.corp", "file.corp");
+
+  /* Check that SERVFAIL and REFUSED responses do not alter the search
+     path resolution.  */
+  rcode_override_server_index = 0;
+  rcode_override = ns_r_servfail;
+  do_both ("hostname", "hostname.usersys.example.com");
+  do_both ("large", "large.example.com");
+  do_both ("large-servfail", "large-servfail.example.com");
+  rcode_override = ns_r_refused;
+  do_both ("hostname", "hostname.usersys.example.com");
+  do_both ("large", "large.example.com");
+  do_both ("large-servfail", "large-servfail.example.com");
+  /* Likewise, but with an NXDOMAIN for the first search path
+     entry.  */
+  rcode_override = ns_r_servfail;
+  do_both ("mail", "mail.corp.example.com");
+  rcode_override = ns_r_refused;
+  do_both ("mail", "mail.corp.example.com");
+  /* Likewise, but with ndots handling.  */
+  rcode_override = ns_r_servfail;
+  do_both ("file.corp", "file.corp");
+  rcode_override = ns_r_refused;
+  do_both ("file.corp", "file.corp");
+
+  resolv_test_end (obj);
+}
+
+static int
+do_test (void)
+{
+  for (int unconnectable_server = 0; unconnectable_server < 2;
+       ++unconnectable_server)
+    do_test_all (unconnectable_server);
+  return 0;
+}
+
+#include <support/test-driver.c>