[glibc/release/2.34/master] nss_dns: Remove remnants of IPv6 address mapping

[glibc/release/2.34/master] nss_dns: Remove remnants of IPv6 address mapping

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=7267341ec1b5c591c2e7946d0604d3cf1423db7d

commit 7267341ec1b5c591c2e7946d0604d3cf1423db7d
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Aug 30 10:02:49 2022 +0200

    nss_dns: Remove remnants of IPv6 address mapping
    
    res_use_inet6 always returns false since commit 3f8b44be0a658266adff5
    ("resolv: Remove support for RES_USE_INET6 and the inet6 option").
    
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
    (cherry picked from commit a7fc30b522a0cd7c8c5e7e285b9531b704e02f04)

Diff:
---
 resolv/README             |  3 --
 resolv/mapv4v6addr.h      | 69 --------------------------------------
 resolv/mapv4v6hostent.h   | 84 -----------------------------------------------
 resolv/nss_dns/dns-host.c | 54 +++++-------------------------
 4 files changed, 9 insertions(+), 201 deletions(-)

diff --git a/resolv/README b/resolv/README
index 514e9bb617..2146bc3b27 100644
--- a/resolv/README
+++ b/resolv/README
@@ -146,6 +146,3 @@ res_libc.c is home-brewn, although parts of it are taken from res_data.c.
 
 res_hconf.c and res_hconf.h were contributed by David Mosberger, and
 do not come from BIND.
-
-The files gethnamaddr.c, mapv4v6addr.h and mapv4v6hostent.h are
-leftovers from BIND 4.9.7.
diff --git a/resolv/mapv4v6addr.h b/resolv/mapv4v6addr.h
deleted file mode 100644
index 7f85f7d5e3..0000000000
--- a/resolv/mapv4v6addr.h
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
- * ++Copyright++ 1985, 1988, 1993
- * -
- * Copyright (c) 1985, 1988, 1993
- *    The Regents of the University of California.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * -
- * Portions Copyright (c) 1993 by Digital Equipment Corporation.
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies, and that
- * the name of Digital Equipment Corporation not be used in advertising or
- * publicity pertaining to distribution of the document or software without
- * specific, written prior permission.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
- * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
- * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
- * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
- * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
- * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
- * SOFTWARE.
- * -
- * --Copyright--
- */
-
-#include <string.h>
-#include <arpa/nameser.h>
-
-static void
-map_v4v6_address (const char *src, char *dst)
-{
-  u_char *p = (u_char *) dst;
-  int i;
-
-  /* Move the IPv4 part to the right position.  */
-  memcpy (dst + 12, src, INADDRSZ);
-
-  /* Mark this ipv6 addr as a mapped ipv4. */
-  for (i = 0; i < 10; i++)
-    *p++ = 0x00;
-  *p++ = 0xff;
-  *p = 0xff;
-}
diff --git a/resolv/mapv4v6hostent.h b/resolv/mapv4v6hostent.h
deleted file mode 100644
index c11038adf3..0000000000
--- a/resolv/mapv4v6hostent.h
+++ /dev/null
@@ -1,84 +0,0 @@
-/*
- * ++Copyright++ 1985, 1988, 1993
- * -
- * Copyright (c) 1985, 1988, 1993
- *    The Regents of the University of California.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * -
- * Portions Copyright (c) 1993 by Digital Equipment Corporation.
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies, and that
- * the name of Digital Equipment Corporation not be used in advertising or
- * publicity pertaining to distribution of the document or software without
- * specific, written prior permission.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
- * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
- * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
- * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
- * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
- * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
- * SOFTWARE.
- * -
- * --Copyright--
- */
-
-#include <arpa/nameser.h>
-#include <sys/socket.h>
-
-typedef union {
-    int32_t al;
-    char ac;
-} align;
-
-static int
-map_v4v6_hostent (struct hostent *hp, char **bpp, int *lenp)
-{
-  char **ap;
-
-  if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
-    return 0;
-  hp->h_addrtype = AF_INET6;
-  hp->h_length = IN6ADDRSZ;
-  for (ap = hp->h_addr_list; *ap; ap++)
-    {
-      int i = sizeof (align) - ((u_long) *bpp % sizeof (align));
-
-      if (*lenp < (i + IN6ADDRSZ))
-	/* Out of memory.  */
-	return 1;
-      *bpp += i;
-      *lenp -= i;
-      map_v4v6_address (*ap, *bpp);
-      *ap = *bpp;
-      *bpp += IN6ADDRSZ;
-      *lenp -= IN6ADDRSZ;
-    }
-  return 0;
-}
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index baca22c4c2..ecbe2736a4 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -88,10 +88,6 @@
 #include <resolv/resolv-internal.h>
 #include <resolv/resolv_context.h>
 
-/* Get implementations of some internal functions.  */
-#include <resolv/mapv4v6addr.h>
-#include <resolv/mapv4v6hostent.h>
-
 #define RESOLVSORT
 
 #if PACKETSZ > 65536
@@ -117,7 +113,7 @@ static enum nss_status getanswer_r (struct resolv_context *ctx,
 				    const char *qname, int qtype,
 				    struct hostent *result, char *buffer,
 				    size_t buflen, int *errnop, int *h_errnop,
-				    int map, int32_t *ttlp, char **canonp);
+				    int32_t *ttlp, char **canonp);
 static enum nss_status getanswer_ptr (unsigned char *packet, size_t packetlen,
 				      struct alloc_buffer *abuf,
 				      char **hnamep, int *errnop,
@@ -190,7 +186,6 @@ gethostbyname3_context (struct resolv_context *ctx,
   char tmp[NS_MAXDNAME];
   int size, type, n;
   const char *cp;
-  int map = 0;
   int olderr = errno;
   enum nss_status status;
 
@@ -251,32 +246,12 @@ gethostbyname3_context (struct resolv_context *ctx,
 	*errnop = EAGAIN;
       else
 	__set_errno (olderr);
-
-      /* If we are looking for an IPv6 address and mapping is enabled
-	 by having the RES_USE_INET6 bit in _res.options set, we try
-	 another lookup.  */
-      if (af == AF_INET6 && res_use_inet6 ())
-	n = __res_context_search (ctx, name, C_IN, T_A, host_buffer.buf->buf,
-				  host_buffer.buf != orig_host_buffer
-				  ? MAXPACKET : 1024, &host_buffer.ptr,
-				  NULL, NULL, NULL, NULL);
-
-      if (n < 0)
-	{
-	  if (host_buffer.buf != orig_host_buffer)
-	    free (host_buffer.buf);
-	  return status;
-	}
-
-      map = 1;
-
-      result->h_addrtype = AF_INET;
-      result->h_length = INADDRSZ;
     }
+  else
+    status = getanswer_r
+      (ctx, host_buffer.buf, n, name, type, result, buffer, buflen,
+       errnop, h_errnop, ttlp, canonp);
 
-  status = getanswer_r
-    (ctx, host_buffer.buf, n, name, type, result, buffer, buflen,
-     errnop, h_errnop, map, ttlp, canonp);
   if (host_buffer.buf != orig_host_buffer)
     free (host_buffer.buf);
   return status;
@@ -322,13 +297,8 @@ _nss_dns_gethostbyname_r (const char *name, struct hostent *result,
       *h_errnop = NETDB_INTERNAL;
       return NSS_STATUS_UNAVAIL;
     }
-  status = NSS_STATUS_NOTFOUND;
-  if (res_use_inet6 ())
-    status = gethostbyname3_context (ctx, name, AF_INET6, result, buffer,
-				     buflen, errnop, h_errnop, NULL, NULL);
-  if (status == NSS_STATUS_NOTFOUND)
-    status = gethostbyname3_context (ctx, name, AF_INET, result, buffer,
-				     buflen, errnop, h_errnop, NULL, NULL);
+  status = gethostbyname3_context (ctx, name, AF_INET, result, buffer,
+				   buflen, errnop, h_errnop, NULL, NULL);
   __resolv_context_put (ctx);
   return status;
 }
@@ -627,7 +597,7 @@ static enum nss_status
 getanswer_r (struct resolv_context *ctx,
 	     const querybuf *answer, int anslen, const char *qname, int qtype,
 	     struct hostent *result, char *buffer, size_t buflen,
-	     int *errnop, int *h_errnop, int map, int32_t *ttlp, char **canonp)
+	     int *errnop, int *h_errnop, int32_t *ttlp, char **canonp)
 {
   struct host_data
   {
@@ -643,7 +613,6 @@ getanswer_r (struct resolv_context *ctx,
   char *bp, **ap, **hap;
   char tbuf[MAXDNAME];
   u_char packtmp[NS_MAXCDNAME];
-  int have_to_map = 0;
   uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
   buffer += pad;
   buflen = buflen > pad ? buflen - pad : 0;
@@ -824,9 +793,7 @@ getanswer_r (struct resolv_context *ctx,
 	  continue;
 	}
 
-      if (type == T_A && qtype == T_AAAA && map)
-	have_to_map = 1;
-      else if (__glibc_unlikely (type != qtype))
+      if (__glibc_unlikely (type != qtype))
 	{
 	  cp += n;
 	  continue;			/* XXX - had_error++ ? */
@@ -923,9 +890,6 @@ getanswer_r (struct resolv_context *ctx,
 	  linebuflen -= n;
 	}
 
-      if (have_to_map)
-	if (map_v4v6_hostent (result, &bp, &linebuflen))
-	  goto too_small;
       *h_errnop = NETDB_SUCCESS;
       return NSS_STATUS_SUCCESS;
     }