resolv: Move dn_expand to its own file and into libc

And reformat to GNU style.

This switches back to the dn_expand name for the ABI symbol and turns
__dn_expand into a compatibility symbol.  With the improved namespace
management in current glibc, it is no longer necessary to use a
private namespace symbol.  To avoid old code binding to a
GLIBC_PRIVATE symbol by accident, use __libc_dn_expand for the
internal symbol name.

The symbols dn_expand, __dnexpand were moved using
scripts/move-symbol-to-libc.py, followed by an adjustment to make
dn_expand the only GLIBC_2.34 symbol.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

11 files changed, 134 insertions, 44 deletions

diff --git a/resolv/Makefile b/resolv/Makefile
index 64600ab845..3e7de81fb5 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -28,6 +28,7 @@ headers	:= resolv.h bits/types/res_state.h \
 	   sys/bitypes.h
 
 routines := \
+  dn_expand \
   herror \
   inet_addr \
   inet_ntop \
diff --git a/resolv/Versions b/resolv/Versions
index a676be2e42..4a9203042f 100644
--- a/resolv/Versions
+++ b/resolv/Versions
@@ -3,6 +3,7 @@ libc {
     __h_errno_location;
     __res_randomid;
     _res;
+    dn_expand;
     h_errlist;
     h_nerr;
     herror;
@@ -10,6 +11,7 @@ libc {
     res_init;
   }
   GLIBC_2.2 {
+    __dn_expand;
     __res_init;
     __res_nclose;
     __res_ninit;
@@ -40,6 +42,7 @@ libc {
     gai_suspend;
     getaddrinfo_a;
 %endif
+    dn_expand;
     ns_name_compress;
     ns_name_ntop;
     ns_name_pack;
@@ -55,6 +58,7 @@ libc {
     __h_errno;
     __inet_aton_exact;
     __inet_pton_length;
+    __libc_dn_expand;
     __ns_name_compress;
     __ns_name_ntop;
     __ns_name_pack;
@@ -120,7 +124,6 @@ libresolv {
     _res_opcodes;
     _res_resultcodes;
     _sethtent;
-    dn_expand;
     inet_net_ntop;
     inet_net_pton;
     inet_neta;
@@ -135,7 +138,6 @@ libresolv {
     res_send_setrhook;
   }
   GLIBC_2.2 {
-    __dn_expand;
     __res_hostalias;
     __res_mkquery;
     __res_nmkquery;
diff --git a/resolv/compat-gethnamaddr.c b/resolv/compat-gethnamaddr.c
index 0e24dcbbcc..1c630fcb3d 100644
--- a/resolv/compat-gethnamaddr.c
+++ b/resolv/compat-gethnamaddr.c
@@ -179,7 +179,7 @@ getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 		__set_h_errno (NO_RECOVERY);
 		return (NULL);
 	}
-	n = dn_expand(answer->buf, eom, cp, bp, buflen);
+	n = __libc_dn_expand (answer->buf, eom, cp, bp, buflen);
 	if ((n < 0) || !(*name_ok)(bp)) {
 		__set_h_errno (NO_RECOVERY);
 		return (NULL);
@@ -210,7 +210,7 @@ getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 	haveanswer = 0;
 	had_error = 0;
 	while (ancount-- > 0 && cp < eom && !had_error) {
-		n = dn_expand(answer->buf, eom, cp, bp, buflen);
+		n = __libc_dn_expand (answer->buf, eom, cp, bp, buflen);
 		if ((n < 0) || !(*name_ok)(bp)) {
 			had_error++;
 			continue;
@@ -233,7 +233,8 @@ getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 			if (ap >= &host_aliases[MAXALIASES-1])
 				continue;
-			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
+			n = __libc_dn_expand (answer->buf, eom, cp,
+					      tbuf, sizeof tbuf);
 			if ((n < 0) || !(*name_ok)(tbuf)) {
 				had_error++;
 				continue;
@@ -265,7 +266,8 @@ getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 			continue;
 		}
 		if (qtype == T_PTR && type == T_CNAME) {
-			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
+			n = __libc_dn_expand (answer->buf, eom, cp,
+					      tbuf, sizeof tbuf);
 			if (n < 0 || !res_dnok(tbuf)) {
 				had_error++;
 				continue;
@@ -302,7 +304,8 @@ getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 				cp += n;
 				continue;	/* XXX - had_error++ ? */
 			}
-			n = dn_expand(answer->buf, eom, cp, bp, buflen);
+			n = __libc_dn_expand (answer->buf, eom, cp,
+					      bp, buflen);
 			if ((n < 0) || !res_hnok(bp)) {
 				had_error++;
 				break;
diff --git a/resolv/dn_expand.c b/resolv/dn_expand.c
new file mode 100644
index 0000000000..0235b34eb4
--- /dev/null
+++ b/resolv/dn_expand.c
@@ -0,0 +1,112 @@
+/* Expanding a compressed DNS domain name to its presentation form.
+   Copyright (C) 1995-2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+/*
+ * Copyright (c) 1985, 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.
+ */
+
+/*
+ * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
+ *
+ * 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.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
+ * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
+ * CONSORTIUM 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.
+ */
+
+#include <arpa/nameser.h>
+#include <resolv.h>
+#include <shlib-compat.h>
+
+/* Expand compressed domain name COMP_DN to full domain name.  MSG is
+   a pointer to the beginning of the message, EOMORIG points to the
+   first location after the message, EXP_DN is a pointer to a buffer
+   of size LENGTH for the result.  Returns size of compressed name or
+   -1 if there was an error.  */
+int
+___dn_expand (const unsigned char *msg, const unsigned char *eom,
+              const unsigned char *src, char *dst, int dstsiz)
+{
+  int n = __ns_name_uncompress (msg, eom, src, dst, (size_t) dstsiz);
+  if (n > 0 && dst[0] == '.')
+    dst[0] = '\0';
+  return n;
+}
+versioned_symbol (libc, ___dn_expand, dn_expand, GLIBC_2_34);
+versioned_symbol (libc, ___dn_expand, __libc_dn_expand, GLIBC_PRIVATE);
+libc_hidden_ver (___dn_expand, __libc_dn_expand);
+
+#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2)
+compat_symbol (libresolv, ___dn_expand, dn_expand, GLIBC_2_0);
+#endif
+#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
+compat_symbol (libresolv, ___dn_expand, __dn_expand, GLIBC_2_2);
+#endif
diff --git a/resolv/ns_parse.c b/resolv/ns_parse.c
index 863b20a9f7..8ae72e7e1f 100644
--- a/resolv/ns_parse.c
+++ b/resolv/ns_parse.c
@@ -154,8 +154,8 @@ ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 	}
 
 	/* Do the parse. */
-	b = dn_expand(handle->_msg, handle->_eom,
-		      handle->_msg_ptr, rr->name, NS_MAXDNAME);
+	b = __libc_dn_expand (handle->_msg, handle->_eom,
+			      handle->_msg_ptr, rr->name, NS_MAXDNAME);
 	if (b < 0)
 		return (-1);
 	handle->_msg_ptr += b;
diff --git a/resolv/ns_print.c b/resolv/ns_print.c
index d61f5044b1..9a9602d74c 100644
--- a/resolv/ns_print.c
+++ b/resolv/ns_print.c
@@ -693,7 +693,7 @@ addname(const u_char *msg, size_t msglen,
 	char *save_buf = *buf;
 	int n;
 
-	n = dn_expand(msg, msg + msglen, *pp, *buf, *buflen);
+	n = __libc_dn_expand (msg, msg + msglen, *pp, *buf, *buflen);
 	if (n < 0)
 		goto enospc;	/*%< Guess. */
 	newlen = prune_origin(*buf, origin);
diff --git a/resolv/nss_dns/dns-canon.c b/resolv/nss_dns/dns-canon.c
index 1cdc9a86c9..b7340d7b9e 100644
--- a/resolv/nss_dns/dns-canon.c
+++ b/resolv/nss_dns/dns-canon.c
@@ -125,8 +125,8 @@ _nss_dns_getcanonname_r (const char *name, char *buffer, size_t buflen,
 	      if (type == qtypes[i])
 		{
 		  /* We found the record.  */
-		  s = __dn_expand (ansp.buf->buf, endptr, namestart,
-				   buffer, buflen);
+		  s = __libc_dn_expand (ansp.buf->buf, endptr, namestart,
+					buffer, buflen);
 		  if (s < 0)
 		    {
 		      if (errno != EMSGSIZE)
diff --git a/resolv/res_comp.c b/resolv/res_comp.c
index c53788643a..42e73a1f00 100644
--- a/resolv/res_comp.c
+++ b/resolv/res_comp.c
@@ -93,25 +93,6 @@
 #include <unistd.h>
 
 /*
- * Expand compressed domain name 'comp_dn' to full domain name.
- * 'msg' is a pointer to the beginning of the message,
- * 'eomorig' points to the first location after the message,
- * 'exp_dn' is a pointer to a buffer of size 'length' for the result.
- * Return size of compressed name or -1 if there was an error.
- */
-int
-dn_expand(const u_char *msg, const u_char *eom, const u_char *src,
-	  char *dst, int dstsiz)
-{
-	int n = ns_name_uncompress(msg, eom, src, dst, (size_t)dstsiz);
-
-	if (n > 0 && dst[0] == '.')
-		dst[0] = '\0';
-	return (n);
-}
-libresolv_hidden_def (dn_expand)
-
-/*
  * Pack domain name 'exp_dn' in presentation form into 'comp_dn'.
  * Return the size of the compressed name or -1.
  * 'length' is the size of the array pointed to by 'comp_dn'.
@@ -268,11 +249,3 @@ void __putshort(uint16_t src, u_char *dst) { ns_put16(src, dst); }
 libresolv_hidden_def (__putshort)
 uint32_t _getlong(const u_char *src) { return (ns_get32(src)); }
 uint16_t _getshort(const u_char *src) { return (ns_get16(src)); }
-
-
-#include <shlib-compat.h>
-
-#if SHLIB_COMPAT(libresolv, GLIBC_2_0, GLIBC_2_2)
-# undef dn_expand
-weak_alias (__dn_expand, dn_expand);
-#endif
diff --git a/resolv/res_debug.c b/resolv/res_debug.c
index 844269cffa..030df0aa90 100644
--- a/resolv/res_debug.c
+++ b/resolv/res_debug.c
@@ -335,7 +335,7 @@ p_cdnname(const u_char *cp, const u_char *msg, int len, FILE *file) {
 	char name[MAXDNAME];
 	int n;
 
-	if ((n = dn_expand(msg, msg + len, cp, name, sizeof name)) < 0)
+	if ((n = __libc_dn_expand (msg, msg + len, cp, name, sizeof name)) < 0)
 		return (NULL);
 	if (name[0] == '\0')
 		putc('.', file);
@@ -359,7 +359,7 @@ p_fqnname (const u_char *cp, const u_char *msg, int msglen, char *name,
 {
 	int n, newlen;
 
-	if ((n = dn_expand(msg, cp + msglen, cp, name, namelen)) < 0)
+	if ((n = __libc_dn_expand (msg, cp + msglen, cp, name, namelen)) < 0)
 		return (NULL);
 	newlen = strlen(name);
 	if (newlen == 0 || name[newlen - 1] != '.') {
diff --git a/resolv/res_send.c b/resolv/res_send.c
index a70f3dec05..b6139c7d62 100644
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -268,7 +268,7 @@ res_nameinquery(const char *name, int type, int class,
 		char tname[MAXDNAME+1];
 		int n, ttype, tclass;
 
-		n = dn_expand(buf, eom, cp, tname, sizeof tname);
+		n = __libc_dn_expand (buf, eom, cp, tname, sizeof tname);
 		if (n < 0)
 			return (-1);
 		cp += n;
@@ -381,7 +381,7 @@ res_queriesmatch(const u_char *buf1, const u_char *eom1,
 		char tname[MAXDNAME+1];
 		int n, ttype, tclass;
 
-		n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
+		n = __libc_dn_expand (buf1, eom1, cp, tname, sizeof tname);
 		if (n < 0)
 			return (-1);
 		cp += n;
diff --git a/resolv/resolv.h b/resolv/resolv.h
index 02a35173e9..7232d81a3b 100644
--- a/resolv/resolv.h
+++ b/resolv/resolv.h
@@ -212,7 +212,6 @@ __END_DECLS
 #define b64_pton		__b64_pton
 #define dn_comp			__dn_comp
 #define dn_count_labels		__dn_count_labels
-#define dn_expand		__dn_expand
 #define dn_skipname		__dn_skipname
 #define fp_resstat		__fp_resstat
 #define loc_aton		__loc_aton