resolv: Remove support for RES_USE_INET6 and the inet6 option

This functionality was deprecated in glibc 2.25.

This commit only includes the core changes to remove the
functionality.  It does not remove the RES_USE_INET6 handling in the
individual NSS service modules and the res_use_inet6 function.
These changes will happen in future commits.

15 files changed, 61 insertions, 680 deletions

diff --git a/ChangeLog b/ChangeLog
index 5ad8875464..bc43b72067 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,40 @@
+2019-04-08  Florian Weimer  <fweimer@redhat.com>
+
+	resolv: Remove support for RES_USE_INET6 and the inet6 option.
+	* nscd/aicache.c (addhstaiX): Do not disable RES_USE_INET6.
+	* nscd/nscd_gehst_r.c (__nscd_gethostbyname_r): Always use
+	GETHOSTBYNAME.
+	* resolv/Makefile (tests): Remove tst-res_use_inet6.
+	(tests-internal): Update justification for tst-resolv-res_init,
+	tst-resolv-res_init-thread.
+	(tst-res_use_inet6): Remove target.
+	(CFLAGS-tst-res_use_inet6.c): Do not set variable.
+	* resolv/res_debug.c (p_option): Remove "inet6" support.
+	* resolv/res_init.c (res_setoptions): Likewise.
+	* resolv/res_use_inet6.h: Remove file.
+	* resolv/resolv-internal.h (DEPRECATED_RES_USE_INET6): Remove
+	definition.
+	(res_use_inet6): Always return false.
+	* resolv/resolv.h (RES_USE_INET6): Remove definition.
+	* resolv/resolv_context.h: Adjust file comment.
+	(struct resolv_context): Update comment on __next field.
+	(__resolv_context_put): Update comment.
+	* resolv/tst-res_use_inet6.c: Remove file.
+	* resolv/tst-resolv-res_init-skeleton.c (print_resp): Remove
+	"inet6" support.
+	(test_cases): Adjust test case.
+	* resolv/tst-resolv-threads.c (byname_inet6) Remove function.
+	(thread_byname2_af_inet6): Use old byname_inet6 code.
+	(thread_byname_inet6, thread_byname2_af_inet6): Remove functions.
+	(gai): Remove do_inet6 argument.
+	(thread_gai_inet, thread_gai_inet6, thread_gai_unspec): Adjust.
+	(thread_gai_inet_inet6, thread_gai_inet6_inet6)
+	(thread_gai_unspec_inet6): Remove functions.
+	(do_test): Adjust thread_funcs.
+	* sysdeps/posix/getaddrinfo.c (gethosts): Do not restore
+	RES_USE_INET6 flag.
+	(gaih_inet): Do not disable RES_USE_INET6 flag.
+
 2019-04-05  Anton Youdkevitch <anton.youdkevitch@bell-sw.com>
 
 	* sysdeps/aarch64/multiarch/memcpy_thunderx2.S: Cleanup branching
diff --git a/NEWS b/NEWS
index 4ad1ae65af..53011b61e1 100644
--- a/NEWS
+++ b/NEWS
@@ -35,6 +35,9 @@ Deprecated and removed features, and other changes affecting compatibility:
 * The obsolete and never-implemented XSI STREAMS header files <stropts.h>
   and <sys/stropts.h> have been removed.
 
+* Support for the "inet6" option in /etc/resolv.conf and the RES_USE_INET6
+  resolver flag (deprecated in glibc 2.25) have been removed.
+
 Changes to build and runtime requirements:
 
 * GCC 6.2 or later is required to build the GNU C Library.
diff --git a/nscd/aicache.c b/nscd/aicache.c
index cf9b91d149..5b94e2aa9e 100644
--- a/nscd/aicache.c
+++ b/nscd/aicache.c
@@ -27,7 +27,6 @@
 #include <sys/mman.h>
 #include <resolv/resolv-internal.h>
 #include <resolv/resolv_context.h>
-#include <resolv/res_use_inet6.h>
 #include <scratch_buffer.h>
 
 #include "dbg_log.h"
@@ -100,12 +99,8 @@ addhstaiX (struct database_dyn *db, int fd, request_header *req,
     no_more = 0;
   nip = hosts_database;
 
-  /* Initialize configurations.  If we are looking for both IPv4 and
-     IPv6 address we don't want the lookup functions to automatically
-     promote IPv4 addresses to IPv6 addresses.  Therefore, use the
-     _no_inet6 variant.  */
+  /* Initialize configurations.  */
   struct resolv_context *ctx = __resolv_context_get ();
-  bool enable_inet6 = __resolv_context_disable_inet6 (ctx);
   if (ctx == NULL)
     no_more = 1;
 
@@ -513,7 +508,6 @@ next_nip:
    }
 
  out:
-  __resolv_context_enable_inet6 (ctx, enable_inet6);
   __resolv_context_put (ctx);
 
   if (dataset != NULL && !alloca_used)
diff --git a/nscd/nscd_gethst_r.c b/nscd/nscd_gethst_r.c
index 97c6190c95..f4c5849862 100644
--- a/nscd/nscd_gethst_r.c
+++ b/nscd/nscd_gethst_r.c
@@ -40,11 +40,7 @@ __nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,
 			char *buffer, size_t buflen, struct hostent **result,
 			int *h_errnop)
 {
-  request_type reqtype;
-
-  reqtype = res_use_inet6 () ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
-
-  return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
+  return nscd_gethst_r (name, strlen (name) + 1, GETHOSTBYNAME, resultbuf,
 			buffer, buflen, result, h_errnop);
 }
 
diff --git a/resolv/Makefile b/resolv/Makefile
index ebe1b733f2..3f84443742 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -52,7 +52,6 @@ tests += \
   tst-ns_name_pton \
   tst-res_hconf_reorder \
   tst-res_hnok \
-  tst-res_use_inet6 \
   tst-resolv-basic \
   tst-resolv-binary \
   tst-resolv-edns \
@@ -70,13 +69,10 @@ tests += \
   tst-resolv-ai_idn-nolibidn2 \
   tst-resolv-canonname \
 
-# uses DEPRECATED_RES_USE_INET6 from <resolv-internal.h>.
+# Needs resolv_context.
 tests-internal += \
   tst-resolv-res_init \
   tst-resolv-res_init-thread \
-
-# Needs resolv_context.
-tests-internal += \
   tst-resolv-res_ninit \
   tst-resolv-threads \
 
@@ -175,7 +171,6 @@ $(objpfx)mtrace-tst-resolv-res_ninit.out: $(objpfx)tst-resolv-res_ninit.out
 
 $(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-ai_idn: \
   $(libdl) $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-ai_idn-latin1: \
@@ -211,7 +206,3 @@ $(objpfx)tst-ns_name_compress: $(objpfx)libresolv.so
 $(objpfx)tst-ns_name_pton: $(objpfx)libresolv.so
 $(objpfx)tst-res_hnok: $(objpfx)libresolv.so
 $(objpfx)tst-p_secstodate: $(objpfx)libresolv.so
-
-
-# This test case uses the deprecated RES_USE_INET6 resolver option.
-CFLAGS-tst-res_use_inet6.c += -Wno-error
diff --git a/resolv/res_debug.c b/resolv/res_debug.c
index 7681ad4639..e4664c1da6 100644
--- a/resolv/res_debug.c
+++ b/resolv/res_debug.c
@@ -607,7 +607,6 @@ p_option(u_long option) {
 	case RES_INSECURE1:	return "insecure1";
 	case RES_INSECURE2:	return "insecure2";
 	case RES_NOALIASES:	return "noaliases";
-	case DEPRECATED_RES_USE_INET6:	return "inet6";
 	case RES_ROTATE:	return "rotate";
 	case RES_USE_EDNS0:	return "edns0";
 	case RES_SNGLKUP:	return "single-request";
diff --git a/resolv/res_init.c b/resolv/res_init.c
index 265e3cc6e3..936fbcb7bd 100644
--- a/resolv/res_init.c
+++ b/resolv/res_init.c
@@ -672,7 +672,6 @@ res_setoptions (struct resolv_conf_parser *parser, const char *options)
             unsigned long int flag;
           } options[] = {
 #define STRnLEN(str) str, sizeof (str) - 1
-            { STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },
             { STRnLEN ("rotate"), 0, RES_ROTATE },
             { STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
             { STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
diff --git a/resolv/res_use_inet6.h b/resolv/res_use_inet6.h
deleted file mode 100644
index a4ed9c34bb..0000000000
--- a/resolv/res_use_inet6.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/* Support functions for handling RES_USE_INET6 in getaddrinfo/nscd.
-   Copyright (C) 2017-2019 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/>.  */
-
-#ifndef _RES_USE_INET6_H
-#define _RES_USE_INET6_H
-
-#include <resolv/resolv_context.h>
-#include <resolv/resolv-internal.h>
-
-/* Ensure that RES_USE_INET6 is disabled in *CTX.  Return true if
-   __resolv_context_enable_inet6 below should enable RES_USE_INET6
-   again.  */
-static inline bool
-__resolv_context_disable_inet6 (struct resolv_context *ctx)
-{
-  if (ctx != NULL && ctx->resp->options & DEPRECATED_RES_USE_INET6)
-    {
-      ctx->resp->options &= ~DEPRECATED_RES_USE_INET6;
-      return true;
-    }
-  else
-    return false;
-}
-
-/* If ENABLE, re-enable RES_USE_INET6 in *CTX.  To be paired with
-   __resolv_context_disable_inet6.  */
-static inline void
-__resolv_context_enable_inet6 (struct resolv_context *ctx, bool enable)
-{
-  if (ctx != NULL && enable)
-    ctx->resp->options |= DEPRECATED_RES_USE_INET6;
-}
-
-#endif
diff --git a/resolv/resolv-internal.h b/resolv/resolv-internal.h
index 1500adc607..3aca6804f4 100644
--- a/resolv/resolv-internal.h
+++ b/resolv/resolv-internal.h
@@ -27,15 +27,12 @@
 #define RES_F_CONN      0x00000002 /* Socket is connected.  */
 #define RES_F_EDNS0ERR  0x00000004 /* EDNS0 caused errors.  */
 
-
-/* Internal version of RES_USE_INET6 which does not trigger a
-   deprecation warning.  */
-#define DEPRECATED_RES_USE_INET6 0x00002000
-
+/* Legacy function.  This needs to be removed once all NSS modules
+   have been adjusted.  */
 static inline bool
 res_use_inet6 (void)
 {
-  return _res.options & DEPRECATED_RES_USE_INET6;
+  return false;
 }
 
 enum
diff --git a/resolv/resolv.h b/resolv/resolv.h
index 80a523e5e4..ad053d9d14 100644
--- a/resolv/resolv.h
+++ b/resolv/resolv.h
@@ -118,8 +118,6 @@ struct res_sym {
 #define	RES_INSECURE1	0x00000400	/* type 1 security disabled */
 #define	RES_INSECURE2	0x00000800	/* type 2 security disabled */
 #define	RES_NOALIASES	0x00001000	/* shuts off HOSTALIASES feature */
-#define	RES_USE_INET6	\
-  __glibc_macro_warning ("RES_USE_INET6 is deprecated") 0x00002000
 #define RES_ROTATE	0x00004000	/* rotate ns list after each query */
 #define	RES_NOCHECKNAME \
   __glibc_macro_warning ("RES_NOCHECKNAME is deprecated") 0x00008000
diff --git a/resolv/resolv_context.h b/resolv/resolv_context.h
index a4d97738a7..b1114343e6 100644
--- a/resolv/resolv_context.h
+++ b/resolv/resolv_context.h
@@ -26,9 +26,7 @@
    allocating a new context.  This prevents unexpected reloading of
    the resolver configuration.  Care is taken to keep the context in
    sync with the thread-local _res object.  (This does not happen with
-   __resolv_context_get_override, and __resolv_context_get_no_inet6 may
-   also interpose another context object if RES_USE_INET6 needs to be
-   disabled.)
+   __resolv_context_get_override.)
 
    In contrast to struct __res_state, struct resolv_context is not
    affected by ABI compatibility concerns.
@@ -62,8 +60,8 @@ struct resolv_context
   size_t __refcount;            /* Count of reusages by the get functions.  */
   bool __from_res;              /* True if created from _res.  */
 
-  /* If RES_USE_INET6 was disabled at this level, this field points to
-     the previous context.  */
+  /* Single-linked list of resolver contexts.  Used for memory
+     deallocation on thread cancellation.  */
   struct resolv_context *__next;
 };
 
@@ -75,8 +73,7 @@ struct resolv_context *__resolv_context_get (void)
 libc_hidden_proto (__resolv_context_get)
 
 /* Deallocate the temporary resolver context.  Converse of
-   __resolv_context_get.  Restore the RES_USE_INET6 flag if necessary.
-   Do nothing if CTX is NULL.  */
+   __resolv_context_get.  Do nothing if CTX is NULL.  */
 void __resolv_context_put (struct resolv_context *ctx);
 libc_hidden_proto (__resolv_context_put)
 
diff --git a/resolv/tst-res_use_inet6.c b/resolv/tst-res_use_inet6.c
deleted file mode 100644
index 65145b7b1f..0000000000
--- a/resolv/tst-res_use_inet6.c
+++ /dev/null
@@ -1,509 +0,0 @@
-/* Basic functionality tests for inet6 option processing.
-   Copyright (C) 2016-2019 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 <ctype.h>
-#include <netdb.h>
-#include <resolv.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>
-#include <support/xthread.h>
-
-/* Handle IPv4 reverse lookup responses.  Product a PTR record
-   A-B-C-D.v4.example.  */
-static void
-response_ptr_v4 (const struct resolv_response_context *ctx,
-                 struct resolv_response_builder *b,
-                 const char *qname, uint16_t qclass, uint16_t qtype)
-{
-  int bytes[4];
-  int offset = -1;
-  TEST_VERIFY (sscanf (qname, "%d.%d.%d.%d.in-addr.arpa%n",
-                       bytes + 0, bytes + 1, bytes + 2, bytes + 3,
-                       &offset) == 4);
-  TEST_VERIFY (offset == strlen (qname));
-  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);
-  char *name = xasprintf ("%d-%d-%d-%d.v4.example",
-                          bytes[3], bytes[2], bytes[1], bytes[0]);
-  resolv_response_add_name (b, name);
-  free (name);
-  resolv_response_close_record (b);
-}
-
-/* Handle IPv6 reverse lookup responses.  Produce a PTR record
-   <32 hex digits>.v6.example. */
-static void
-response_ptr_v6 (const struct resolv_response_context *ctx,
-                 struct resolv_response_builder *b,
-                 const char *qname, uint16_t qclass, uint16_t qtype)
-{
-
-  TEST_VERIFY_EXIT (strlen (qname) > 64);
-
-  char bytes[33];
-  for (int i = 0; i < 64; ++i)
-    if ((i % 2) == 0)
-      {
-        TEST_VERIFY (isxdigit ((unsigned char) qname[i]));
-        bytes[31 - i / 2] = qname[i];
-      }
-    else
-      TEST_VERIFY_EXIT (qname[i] == '.');
-  bytes[32] = '\0';
-
-    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);
-  char *name = xasprintf ("%s.v6.example", bytes);
-  resolv_response_add_name (b, name);
-  free (name);
-  resolv_response_close_record (b);
-}
-
-/* Produce a response based on QNAME: Certain characters in the first
-   label of QNAME trigger the inclusion of resource records:
-
-   'a'   A record (IPv4 address)
-   'q'   AAAA record (quad A record, IPv6 address)
-   'p'   PTR record
-   'm'   record type must match QTYPE (no additional records)
-   '6'   stop flag processing if QTYPE == AAAA
-
-   For 'a' and 'q', QTYPE is ignored for record type selection if 'm'
-   is not specified.
-
-   in-addr.arpa and ip6.arpa queries are handled separately in
-   response_ptr_v4 and response_ptr_v6.  */
-static void
-response (const struct resolv_response_context *ctx,
-          struct resolv_response_builder *b,
-          const char *qname, uint16_t qclass, uint16_t qtype)
-{
-  if (strstr (qname, ".in-addr.arpa") != NULL)
-    return response_ptr_v4 (ctx, b, qname, qclass, qtype);
-  else if (strstr (qname, ".ip6.arpa") != NULL)
-    return response_ptr_v6 (ctx, b, qname, qclass, qtype);
-
-  bool include_a = false;
-  bool include_aaaa = false;
-  bool include_match = false;
-  bool include_ptr = false;
-  for (const char *p = qname; *p != '.' && *p != '\0'; ++p)
-    {
-      if (*p == 'a')
-        include_a = true;
-      else if (*p == 'q')
-        include_aaaa = true;
-      else if (*p == 'm')
-        include_match = true;
-      else if (*p == 'p')
-        include_ptr = true;
-      else if (*p == '6' && qtype == T_AAAA)
-        break;
-    }
-  if (include_match)
-    {
-      if (qtype == T_A)
-        include_aaaa = false;
-      else if (qtype == T_AAAA)
-        include_a = false;
-    }
-
-  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);
-    }
-  if (include_ptr)
-    {
-      resolv_response_open_record (b, qname, qclass, T_PTR, 0);
-      resolv_response_add_name (b, "ptr-target.example");
-      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 ("qam.example", "80", &hints, &ai);
-    check_addrinfo ("getaddrinfo AF_UNSPEC qam.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 ("am.example", "80", &hints, &ai);
-    check_addrinfo ("getaddrinfo AF_UNSPEC am.example", ai, ret,
-                    "address: STREAM/TCP 192.0.2.17 80\n");
-    if (ret == 0)
-      freeaddrinfo (ai);
-    ret = getaddrinfo ("qa.example", "80", &hints, &ai);
-    /* Combined A/AAAA responses currently result in address
-       duplication.  */
-    check_addrinfo ("getaddrinfo AF_UNSPEC qa.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 ("qam.example", "80", &hints, &ai);
-    check_addrinfo ("getaddrinfo AF_INET qam.example", ai, ret,
-                    "address: STREAM/TCP 192.0.2.17 80\n");
-    if (ret == 0)
-      freeaddrinfo (ai);
-    ret = getaddrinfo ("am.example", "80", &hints, &ai);
-    check_addrinfo ("getaddrinfo AF_INET am.example", ai, ret,
-                    "address: STREAM/TCP 192.0.2.17 80\n");
-    if (ret == 0)
-      freeaddrinfo (ai);
-    ret = getaddrinfo ("qa.example", "80", &hints, &ai);
-    check_addrinfo ("getaddrinfo AF_INET qa.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 ("qa.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 ("am.example", "80", &hints, &ai);
-    check_addrinfo ("getaddrinfo AF_INET6 am.example", ai, ret,
-                    "error: No address associated with hostname\n");
-    if (ret == 0)
-      freeaddrinfo (ai);
-    ret = getaddrinfo ("qam.example", "80", &hints, &ai);
-    check_addrinfo ("getaddrinfo AF_INET6 qam.example", ai, ret,
-                    "address: STREAM/TCP 2001:db8::1 80\n");
-    if (ret == 0)
-      freeaddrinfo (ai);
-  }
-}
-
-/* Test gethostbyaddr and getnameinfo.  The results are independent of
-   RES_USE_INET6.  */
-static void
-test_reverse (void)
-{
-  {
-    char ipv4[4] = { 192, 0, 2, 17 };
-    check_hostent ("gethostbyaddr AF_INET",
-                   gethostbyaddr (ipv4, sizeof (ipv4), AF_INET),
-                   "name: 192-0-2-17.v4.example\n"
-                   "address: 192.0.2.17\n");
-  }
-  {
-    char ipv6[16]
-      = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
-    check_hostent ("gethostbyaddr AF_INET",
-                   gethostbyaddr (ipv6, sizeof (ipv6), AF_INET6),
-                   "name: 20010db8000000000000000000000001.v6.example\n"
-                   "address: 2001:db8::1\n");
-  }
-
-  {
-    struct sockaddr_in addr =
-      {
-        .sin_family = AF_INET,
-        .sin_addr = { .s_addr = htonl (0xc0000211) },
-        .sin_port = htons (80)
-      };
-    char host[NI_MAXHOST];
-    char service[NI_MAXSERV];
-    int ret = getnameinfo ((struct sockaddr *) &addr, sizeof (addr),
-                           host, sizeof (host), service, sizeof (service),
-                           NI_NUMERICSERV);
-    TEST_VERIFY (ret == 0);
-    TEST_VERIFY (strcmp (host, "192-0-2-17.v4.example") == 0);
-    TEST_VERIFY (strcmp (service, "80") == 0);
-  }
-  {
-    char ipv6[16]
-      = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
-    struct sockaddr_in6 addr =
-      {
-        .sin6_family = AF_INET6,
-        .sin6_port = htons (80),
-      };
-    TEST_VERIFY (sizeof (ipv6) == sizeof (addr.sin6_addr));
-    memcpy (&addr.sin6_addr, ipv6, sizeof (addr.sin6_addr));
-    char host[NI_MAXHOST];
-    char service[NI_MAXSERV];
-    int ret = getnameinfo ((struct sockaddr *) &addr, sizeof (addr),
-                           host, sizeof (host), service, sizeof (service),
-                           NI_NUMERICSERV);
-    TEST_VERIFY (ret == 0);
-    TEST_VERIFY
-      (strcmp (host, "20010db8000000000000000000000001.v6.example") == 0);
-    TEST_VERIFY (strcmp (service, "80") == 0);
-  }
-}
-
-/* Test that gethostbyname2 is mostly not influenced by
-   RES_USE_INET6.  */
-static void
-test_get2_any (void)
-{
-  check_hostent ("gethostbyname2 AF_INET am.example",
-                 gethostbyname2 ("am.example", AF_INET),
-                 "name: am.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname2 AF_INET a.example",
-                 gethostbyname2 ("a.example", AF_INET),
-                 "name: a.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname2 AF_INET qm.example",
-                 gethostbyname2 ("qm.example", AF_INET),
-                 "error: NO_ADDRESS\n");
-  check_hostent ("gethostbyname2 AF_INET q.example",
-                 gethostbyname2 ("q.example", AF_INET),
-                 "error: NO_RECOVERY\n");
-  check_hostent ("gethostbyname2 AF_INET qam.example",
-                 gethostbyname2 ("qam.example", AF_INET),
-                 "name: qam.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname2 AF_INET qa.example",
-                 gethostbyname2 ("qa.example", AF_INET),
-                 "name: qa.example\n"
-                 "address: 192.0.2.17\n");
-
-  check_hostent ("gethostbyname2 AF_INET6 qm.example",
-                 gethostbyname2 ("qm.example", AF_INET6),
-                 "name: qm.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname2 AF_INET6 q.example",
-                 gethostbyname2 ("q.example", AF_INET6),
-                 "name: q.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname2 AF_INET6 qam.example",
-                 gethostbyname2 ("qam.example", AF_INET6),
-                 "name: qam.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname2 AF_INET6 qa.example",
-                 gethostbyname2 ("qa.example", AF_INET6),
-                 "name: qa.example\n"
-                 "address: 2001:db8::1\n");
-  /* Additional AF_INET6 tests depend on RES_USE_INET6; see below.  */
-
-  test_reverse ();
-}
-
-/* gethostbyname2 tests with RES_USE_INET6 disabled.  */
-static void
-test_get2_no_inet6 (void)
-{
-  test_get2_any ();
-
-  check_hostent ("gethostbyname2 AF_INET6 am.example",
-                 gethostbyname2 ("am.example", AF_INET6),
-                 "error: NO_ADDRESS\n");
-  check_hostent ("gethostbyname2 AF_INET6 a.example",
-                 gethostbyname2 ("a.example", AF_INET6),
-                 "error: NO_RECOVERY\n");
-}
-
-/* gethostbyname2 tests with RES_USE_INET6 enabled.  */
-static void
-test_get2_inet6 (void)
-{
-  test_get2_any ();
-
-  check_hostent ("gethostbyname2 AF_INET6 am.example",
-                 gethostbyname2 ("am.example", AF_INET6),
-                 "name: am.example\n"
-                 "address: ::ffff:192.0.2.17\n");
-  check_hostent ("gethostbyname2 AF_INET6 a.example",
-                 gethostbyname2 ("a.example", AF_INET6),
-                 "error: NO_RECOVERY\n");
-}
-
-/* Collection of tests which assume no RES_USE_INET6 flag.  */
-static void
-test_no_inet6 (void)
-{
-  check_hostent ("gethostbyname (\"a.example\")",
-                 gethostbyname ("a.example"),
-                 "name: a.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname (\"qa.example\")",
-                 gethostbyname ("qa.example"),
-                 "name: qa.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname (\"am.example\")",
-                 gethostbyname ("am.example"),
-                 "name: am.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname (\"amp.example\")",
-                 gethostbyname ("amp.example"),
-                 "name: amp.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname (\"qam.example\")",
-                 gethostbyname ("qam.example"),
-                 "name: qam.example\n"
-                 "address: 192.0.2.17\n");
-  check_hostent ("gethostbyname (\"q.example\")",
-                 gethostbyname ("q.example"),
-                 "error: NO_RECOVERY\n");
-  check_hostent ("gethostbyname (\"qm.example\")",
-                 gethostbyname ("qm.example"),
-                 "error: NO_ADDRESS\n");
-  test_get2_no_inet6 ();
-  test_get2_no_inet6 ();
-  test_gai ();
-  test_get2_no_inet6 ();
-  test_get2_no_inet6 ();
-}
-
-static void *
-threadfunc (void *ignored)
-{
-  struct resolv_test *obj = resolv_test_start
-    ((struct resolv_redirect_config)
-     {
-       .response_callback = response
-     });
-
-  TEST_VERIFY ((_res.options & RES_USE_INET6) == 0);
-  test_no_inet6 ();
-
-  _res.options |= RES_USE_INET6;
-  check_hostent ("gethostbyname (\"a.inet6.example\")",
-                 gethostbyname ("a.inet6.example"),
-                 "error: NO_RECOVERY\n");
-  check_hostent ("gethostbyname (\"am.inet6.example\")",
-                 gethostbyname ("am.inet6.example"),
-                 "name: am.inet6.example\n"
-                 "address: ::ffff:192.0.2.17\n");
-  check_hostent ("gethostbyname (\"qa.inet6.example\")",
-                 gethostbyname ("qa.inet6.example"),
-                 "name: qa.inet6.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname (\"qam.inet6.example\")",
-                 gethostbyname ("qam.inet6.example"),
-                 "name: qam.inet6.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname (\"q.inet6.example\")",
-                 gethostbyname ("q.inet6.example"),
-                 "name: q.inet6.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname (\"qm.inet6.example\")",
-                 gethostbyname ("qm.inet6.example"),
-                 "name: qm.inet6.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname (\"amp.inet6.example\")",
-                 gethostbyname ("amp.inet6.example"),
-                 "error: NO_RECOVERY\n");
-  check_hostent ("gethostbyname (\"qmp.inet6.example\")",
-                 gethostbyname ("qmp.inet6.example"),
-                 "name: qmp.inet6.example\n"
-                 "address: 2001:db8::1\n");
-  check_hostent ("gethostbyname (\"ap.inet6.example\")",
-                 gethostbyname ("ap.inet6.example"),
-                 "error: NO_RECOVERY\n");
-  check_hostent ("gethostbyname (\"6ap.inet6.example\")",
-                 gethostbyname ("6ap.inet6.example"),
-                 "name: 6ap.inet6.example\n"
-                 "address: ::ffff:192.0.2.17\n");
-  check_hostent ("gethostbyname (\"am6p.inet6.example\")",
-                 gethostbyname ("am6p.inet6.example"),
-                 "name: am6p.inet6.example\n"
-                 "address: ::ffff:192.0.2.17\n");
-  check_hostent ("gethostbyname (\"qp.inet6.example\")",
-                 gethostbyname ("qp.inet6.example"),
-                 "name: qp.inet6.example\n"
-                 "address: 2001:db8::1\n");
-  test_get2_inet6 ();
-  test_get2_inet6 ();
-  test_gai ();
-  test_get2_inet6 ();
-  test_get2_inet6 ();
-
-  TEST_VERIFY (_res.options & RES_USE_INET6);
-  _res.options &= ~RES_USE_INET6;
-  test_no_inet6 ();
-
-  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-res_init-skeleton.c b/resolv/tst-resolv-res_init-skeleton.c
index e8acebcd5f..678f396c4c 100644
--- a/resolv/tst-resolv-res_init-skeleton.c
+++ b/resolv/tst-resolv-res_init-skeleton.c
@@ -24,7 +24,6 @@
 #include <errno.h>
 #include <gnu/lib-names.h>
 #include <netdb.h>
-#include <resolv/resolv-internal.h> /* For DEPRECATED_RES_USE_INET6.  */
 #include <resolv/resolv_context.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -120,7 +119,6 @@ print_resp (FILE *fp, res_state resp)
         if (resp->retry != RES_DFLRETRY)
           fprintf (fp, " attempts:%d", resp->retry);
         print_option_flag (fp, &options, RES_USEVC, "use-vc");
-        print_option_flag (fp, &options, DEPRECATED_RES_USE_INET6, "inet6");
         print_option_flag (fp, &options, RES_ROTATE, "rotate");
         print_option_flag (fp, &options, RES_USE_EDNS0, "edns0");
         print_option_flag (fp, &options, RES_SNGLKUP,
@@ -560,7 +558,7 @@ struct test_case test_cases[] =
      "nameserver 192.0.2.1\n"
      "nameserver ::1\n"
      "nameserver 192.0.2.2\n",
-     .expected = "options ndots:3 timeout:19 attempts:5 inet6 edns0\n"
+     .expected = "options ndots:3 timeout:19 attempts:5 edns0\n"
      "search corp.example.com example.com\n"
      "; search[0]: corp.example.com\n"
      "; search[1]: example.com\n"
diff --git a/resolv/tst-resolv-threads.c b/resolv/tst-resolv-threads.c
index 52ab92b580..7e87e641cc 100644
--- a/resolv/tst-resolv-threads.c
+++ b/resolv/tst-resolv-threads.c
@@ -276,19 +276,12 @@ thread_byname2 (void *closure)
   return byname (true);
 }
 
-/* Call gethostbyname_r with RES_USE_INET6 (if do_2 is false), or
-   gethostbyname_r with AF_INET6 (if do_2 is true).  */
+/* Test gethostbyname2_r with AF_INET6.  */
 static void *
-byname_inet6 (bool do_2)
+thread_byname2_af_inet6 (void *closure)
 {
   int this_thread = get_thread_number ();
   xpthread_barrier_wait (&barrier);
-  if (!do_2)
-    {
-      res_init ();
-      _res.options |= DEPRECATED_RES_USE_INET6;
-      TEST_VERIFY (strcmp (_res.defdname, "example.com") == 0);
-    }
   for (int i = 0; i < queries_per_thread; ++i)
     {
       char qname[100];
@@ -298,46 +291,19 @@ byname_inet6 (bool do_2)
       char buf[1000];
       struct hostent *e = NULL;
       int herrno;
-      int ret;
-      if (do_2)
-        ret = gethostbyname2_r (qname, AF_INET6, &storage, buf, sizeof (buf),
-                                &e, &herrno);
-      else
-        ret = gethostbyname_r (qname, &storage, buf, sizeof (buf),
-                               &e, &herrno);
-      check_hostent (__func__,
-                     do_2 ? "gethostbyname2_r" : "gethostbyname_r",
-                     qname, ret, e, AF_INET6, i);
+      int ret = gethostbyname2_r (qname, AF_INET6, &storage, buf, sizeof (buf),
+                                  &e, &herrno);
+      check_hostent (__func__, "gethostbyname2_r", qname, ret, e, AF_INET6, i);
     }
   return NULL;
 }
 
-/* Test gethostbyname_r with AF_INET6.  */
-static void *
-thread_byname_inet6 (void *closure)
-{
-  return byname_inet6 (false);
-}
-
-/* Test gethostbyname2_r with AF_INET6.  */
-static void *
-thread_byname2_af_inet6 (void *closure)
-{
-  return byname_inet6 (true);
-}
-
 /* Run getaddrinfo tests for FAMILY.  */
 static void *
-gai (int family, bool do_inet6)
+gai (int family)
 {
   int this_thread = get_thread_number ();
   xpthread_barrier_wait (&barrier);
-  if (do_inet6)
-    {
-      res_init ();
-      _res.options |= DEPRECATED_RES_USE_INET6;
-      check_have_conf ();
-    }
   for (int i = 0; i < queries_per_thread; ++i)
     {
       char qname[100];
@@ -362,42 +328,21 @@ gai (int family, bool do_inet6)
 static void *
 thread_gai_inet (void *closure)
 {
-  return gai (AF_INET, false);
+  return gai (AF_INET);
 }
 
 /* Test getaddrinfo with AF_INET6.  */
 static void *
 thread_gai_inet6 (void *closure)
 {
-  return gai (AF_INET6, false);
+  return gai (AF_INET6);
 }
 
 /* Test getaddrinfo with AF_UNSPEC.  */
 static void *
 thread_gai_unspec (void *closure)
 {
-  return gai (AF_UNSPEC, false);
-}
-
-/* Test getaddrinfo with AF_INET.  */
-static void *
-thread_gai_inet_inet6 (void *closure)
-{
-  return gai (AF_INET, true);
-}
-
-/* Test getaddrinfo with AF_INET6.  */
-static void *
-thread_gai_inet6_inet6 (void *closure)
-{
-  return gai (AF_INET6, true);
-}
-
-/* Test getaddrinfo with AF_UNSPEC.  */
-static void *
-thread_gai_unspec_inet6 (void *closure)
-{
-  return gai (AF_UNSPEC, true);
+  return gai (AF_UNSPEC);
 }
 
 /* Description of the chroot environment used to run the tests.  */
@@ -451,7 +396,7 @@ do_test (void)
        .server_address_overrides = server_addresses,
      });
 
-  enum { thread_count = 10 };
+  enum { thread_count = 6 };
   xpthread_barrier_init (&barrier, NULL, thread_count + 1);
   pthread_t threads[thread_count];
   typedef void *(*thread_func) (void *);
@@ -459,14 +404,10 @@ do_test (void)
     {
       thread_byname,
       thread_byname2,
-      thread_byname_inet6,
       thread_byname2_af_inet6,
       thread_gai_inet,
       thread_gai_inet6,
       thread_gai_unspec,
-      thread_gai_inet_inet6,
-      thread_gai_inet6_inet6,
-      thread_gai_unspec_inet6,
     };
   for (int i = 0; i < thread_count; ++i)
     threads[i] = xpthread_create (NULL, thread_funcs[i], NULL);
diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index aa054b620f..f212d1c601 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -61,7 +61,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <nss.h>
 #include <resolv/resolv-internal.h>
 #include <resolv/resolv_context.h>
-#include <resolv/res_use_inet6.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdio_ext.h>
@@ -255,7 +254,6 @@ convert_hostent_to_gaih_addrtuple (const struct addrinfo *req,
 	break;								      \
       if (!scratch_buffer_grow (tmpbuf))				      \
 	{								      \
-	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);	      \
 	  __resolv_context_put (res_ctx);				      \
 	  result = -EAI_MEMORY;						      \
 	  goto free_and_return;						      \
@@ -266,7 +264,6 @@ convert_hostent_to_gaih_addrtuple (const struct addrinfo *req,
     {									      \
       if (h_errno == NETDB_INTERNAL)					      \
 	{								      \
-	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);	      \
 	  __resolv_context_put (res_ctx);				      \
 	  result = -EAI_SYSTEM;						      \
 	  goto free_and_return;						      \
@@ -280,7 +277,6 @@ convert_hostent_to_gaih_addrtuple (const struct addrinfo *req,
     {									      \
       if (!convert_hostent_to_gaih_addrtuple (req, _family, &th, &addrmem))   \
 	{								      \
-	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);	      \
 	  __resolv_context_put (res_ctx);				      \
 	  result = -EAI_SYSTEM;						      \
 	  goto free_and_return;						      \
@@ -558,7 +554,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
 	  enum nss_status status = NSS_STATUS_UNAVAIL;
 	  int no_more;
 	  struct resolv_context *res_ctx = NULL;
-	  bool res_enable_inet6 = false;
 
 	  /* If we do not have to look for IPv6 addresses or the canonical
 	     name, use the simple, old functions, which do not support
@@ -749,7 +744,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
 	     addresses to IPv6 addresses, so we use the no_inet6
 	     function variant.  */
 	  res_ctx = __resolv_context_get ();
-	  res_enable_inet6 = __resolv_context_disable_inet6 (res_ctx);
 	  if (res_ctx == NULL)
 	    no_more = 1;
 
@@ -785,8 +779,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
 
 		      if (!scratch_buffer_grow (tmpbuf))
 			{
-			  __resolv_context_enable_inet6
-			    (res_ctx, res_enable_inet6);
 			  __resolv_context_put (res_ctx);
 			  result = -EAI_MEMORY;
 			  goto free_and_return;
@@ -886,8 +878,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
 			      canonbuf = getcanonname (nip, at, name);
 			      if (canonbuf == NULL)
 				{
-				  __resolv_context_enable_inet6
-				    (res_ctx, res_enable_inet6);
 				  __resolv_context_put (res_ctx);
 				  result = -EAI_MEMORY;
 				  goto free_and_return;
@@ -932,7 +922,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
 		nip = nip->next;
 	    }
 
-	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);
 	  __resolv_context_put (res_ctx);
 
 	  /* If we have a failure which sets errno, report it using