[PATCH COMMITTED] hesiod: Always use thread-local resolver state [BZ #19573]

[fweimer at redhat dot com (Florian Weimer)]

The Hesiod implementation imported into glibc was enhanced
to support caller-supplied resolver states.  But its only
consumer is nss_hesiod, and it supplies the thread-local
resolver state.  Therefore, this commit changes the Hesiod
implementation to use the thread-local resolver state (_res)
directly.  This fixes bug 19573 because the Hesiod
implementation no longer has to initialize and free any
resolver state.

To avoid any risk of interposition of ABI-incompatible Hesiod
function implementations, this commit marks the Hesiod functions
as hidden.  (They were already hidden using a linker version
script.)

2016-05-02  Florian Weimer  <fweimer@redhat.com>

	[BZ #19573]
	* hesiod/Makefile (libnss_hesiod-routines): Remove hesiod-init.
	* hesiod/nss_hesiod/hesiod-init.c: Remove file.
	* hesiod/nss_hesiod/nss_hesiod.h: Likewise.
	* hesiod/hesiod.h (__hesiod_res_get, __hesiod_res_set): Remove.
	(hesiod_init, hesiod_end, hesiod_to_bind, hesiod_resolve)
	(hesiod_free_list): Mark as hidden.
	* hesiod/hesiod_p (struct hesiod_p): Remove res, free_res,
	res_set, res_get.
	* hesiod/hesiod.c: Remove unnecessary forward declarations.
	(init, __hesiod_res_get, __hesiod_res_set): Remove.
	(hesiod_init): Remove obsolete res_ninit call.
	(hesiod_end): Do not free resolver state.  Do not invoke callback.
	(hesiod_bind): Do not call init.
	(get_txt_records): Use res_mkquery, res_send instead of
	res_nmkquery, res_nsend.
	* hesiod/nss_hesiod/hesiod-grp.c (lookup): Call hesiod_init
	instead of _nss_hesiod_init.
	(_nss_hesiod_initgroups_dyn): Likewise.
	* hesiod/nss_hesiod/hesiod-proto.c (lookup): Likewise.
	* hesiod/nss_hesiod/hesiod-pwd.c (lookup): Likewise.
	* hesiod/nss_hesiod/hesiod-service.c (lookup): Likewise.

diff --git a/hesiod/Makefile b/hesiod/Makefile
index d68a859..2d1966c 100644
--- a/hesiod/Makefile
+++ b/hesiod/Makefile
@@ -28,7 +28,7 @@ extra-libs-others = $(extra-libs)
 subdir-dirs = nss_hesiod
 vpath %.c nss_hesiod
 
-libnss_hesiod-routines	:= hesiod hesiod-grp hesiod-init hesiod-proto \
+libnss_hesiod-routines	:= hesiod hesiod-grp hesiod-proto \
 			   hesiod-pwd hesiod-service
 # Build only shared library
 libnss_hesiod-inhibit-o	= $(filter-out .os,$(object-suffixes))
diff --git a/hesiod/hesiod.c b/hesiod/hesiod.c
index 1869e52..6ecbad1 100644
--- a/hesiod/hesiod.c
+++ b/hesiod/hesiod.c
@@ -1,3 +1,20 @@
+/* Copyright (C) 1997-2016 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/>.  */
+
 /*
  * Copyright (c) 1996,1999 by Internet Software Consortium.
  *
@@ -47,18 +64,9 @@
 
 /* Forward */
 
-int		hesiod_init(void **context);
-void		hesiod_end(void *context);
-char *		hesiod_to_bind(void *context, const char *name,
-			       const char *type);
-char **		hesiod_resolve(void *context, const char *name,
-			       const char *type);
-void		hesiod_free_list(void *context, char **list);
-
 static int	parse_config_file(struct hesiod_p *ctx, const char *filename);
 static char **	get_txt_records(struct hesiod_p *ctx, int class,
 				const char *name);
-static int	init(struct hesiod_p *ctx);
 
 /* Public */
 
@@ -77,7 +85,6 @@ hesiod_init(void **context) {
 
 	ctx->LHS = NULL;
 	ctx->RHS = NULL;
-	ctx->res = NULL;
 	/* Set default query classes. */
 	ctx->classes[0] = C_IN;
 	ctx->classes[1] = C_HS;
@@ -114,11 +121,6 @@ hesiod_init(void **context) {
 		goto cleanup;
 	}
 
-#if 0
-	if (res_ninit(ctx->res) < 0)
-		goto cleanup;
-#endif
-
 	*context = ctx;
 	return (0);
 
@@ -135,12 +137,8 @@ hesiod_end(void *context) {
 	struct hesiod_p *ctx = (struct hesiod_p *) context;
 	int save_errno = errno;
 
-	if (ctx->res)
-		res_nclose(ctx->res);
 	free(ctx->RHS);
 	free(ctx->LHS);
-	if (ctx->res && ctx->free_res)
-		(*ctx->free_res)(ctx->res);
 	free(ctx);
 	__set_errno(save_errno);
 }
@@ -215,10 +213,6 @@ hesiod_resolve(void *context, const char *name, const char *type) {
 
 	if (bindname == NULL)
 		return (NULL);
-	if (init(ctx) == -1) {
-		free(bindname);
-		return (NULL);
-	}
 
 	retvec = get_txt_records(ctx, ctx->classes[0], bindname);
 
@@ -348,13 +342,13 @@ get_txt_records(struct hesiod_p *ctx, int class, const char *name) {
 	/*
 	 * Construct the query and send it.
 	 */
-	n = res_nmkquery(ctx->res, QUERY, name, class, T_TXT, NULL, 0,
+	n = res_mkquery(QUERY, name, class, T_TXT, NULL, 0,
 			 NULL, qbuf, MAX_HESRESP);
 	if (n < 0) {
 		__set_errno(EMSGSIZE);
 		return (NULL);
 	}
-	n = res_nsend(ctx->res, qbuf, n, abuf, MAX_HESRESP);
+	n = res_send(qbuf, n, abuf, MAX_HESRESP);
 	if (n < 0) {
 		__set_errno(ECONNREFUSED);
 		return (NULL);
@@ -447,44 +441,3 @@ get_txt_records(struct hesiod_p *ctx, int class, const char *name) {
 	free(list);
 	return (NULL);
 }
-
-struct __res_state *
-__hesiod_res_get(void *context) {
-	struct hesiod_p *ctx = context;
-
-	if (!ctx->res) {
-		struct __res_state *res;
-		res = (struct __res_state *)calloc(1, sizeof *res);
-		if (res == NULL)
-			return (NULL);
-		__hesiod_res_set(ctx, res, free);
-	}
-
-	return (ctx->res);
-}
-
-void
-__hesiod_res_set(void *context, struct __res_state *res,
-		 void (*free_res)(void *)) {
-	struct hesiod_p *ctx = context;
-
-	if (ctx->res && ctx->free_res) {
-		res_nclose(ctx->res);
-		(*ctx->free_res)(ctx->res);
-	}
-
-	ctx->res = res;
-	ctx->free_res = free_res;
-}
-
-static int
-init(struct hesiod_p *ctx) {
-
-	if (!ctx->res && !__hesiod_res_get(ctx))
-		return (-1);
-
-	if (__res_maybe_init (ctx->res, 0) == -1)
-		return (-1);
-
-	return (0);
-}
diff --git a/hesiod/hesiod.h b/hesiod/hesiod.h
index cb742b0..c4f5356 100644
--- a/hesiod/hesiod.h
+++ b/hesiod/hesiod.h
@@ -1,3 +1,20 @@
+/* Copyright (C) 1997-2016 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/>.  */
+
 /*
  * Copyright (c) 1996,1999 by Internet Software Consortium.
  *
@@ -22,15 +39,12 @@
 #ifndef _HESIOD_H_INCLUDED
 #define _HESIOD_H_INCLUDED
 
-int		hesiod_init (void **context);
-void		hesiod_end (void *context);
+int		hesiod_init (void **context) attribute_hidden;
+void		hesiod_end (void *context) attribute_hidden;
 char *		hesiod_to_bind (void *context, const char *name,
-				const char *type);
+				const char *type) attribute_hidden;
 char **		hesiod_resolve (void *context, const char *name,
-				const char *type);
-void		hesiod_free_list (void *context, char **list);
-struct __res_state * __hesiod_res_get (void *context);
-void		__hesiod_res_set (void *context, struct __res_state *,
-				  void (*)(void *));
+				const char *type) attribute_hidden;
+void		hesiod_free_list (void *context, char **list) attribute_hidden;
 
 #endif /*_HESIOD_H_INCLUDED*/
diff --git a/hesiod/hesiod_p.h b/hesiod/hesiod_p.h
index 0c00c58..859a8df 100644
--- a/hesiod/hesiod_p.h
+++ b/hesiod/hesiod_p.h
@@ -1,3 +1,20 @@
+/* Copyright (C) 1997-2016 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/>.  */
+
 /*
  * Copyright (c) 1996,1999 by Internet Software Consortium.
  *
@@ -31,11 +48,6 @@
 struct hesiod_p {
 	char *		LHS;		/* normally ".ns" */
 	char *		RHS;		/* AKA the default hesiod domain */
-	struct __res_state * res;	/* resolver context */
-	void		(*free_res)(void *);
-	void		(*res_set)(struct hesiod_p *, struct __res_state *,
-				   void (*)(void *));
-	struct __res_state * (*res_get)(struct hesiod_p *);
 	int		classes[2];	/* The class search order. */
 };
 
diff --git a/hesiod/nss_hesiod/hesiod-grp.c b/hesiod/nss_hesiod/hesiod-grp.c
index 7e4ecb4..944e5e0 100644
--- a/hesiod/nss_hesiod/hesiod-grp.c
+++ b/hesiod/nss_hesiod/hesiod-grp.c
@@ -26,8 +26,6 @@
 #include <string.h>
 #include <sys/param.h>
 
-#include "nss_hesiod.h"
-
 /* Get the declaration of the parser function.  */
 #define ENTNAME grent
 #define STRUCTURE group
@@ -58,8 +56,7 @@ lookup (const char *name, const char *type, struct group *grp,
   size_t len;
   int olderr = errno;
 
-  context = _nss_hesiod_init ();
-  if (context == NULL)
+  if (hesiod_init (&context) < 0)
     return NSS_STATUS_UNAVAIL;
 
   list = hesiod_resolve (context, name, type);
@@ -179,8 +176,7 @@ _nss_hesiod_initgroups_dyn (const char *user, gid_t group, long int *start,
   gid_t *groups = *groupsp;
   int save_errno;
 
-  context = _nss_hesiod_init ();
-  if (context == NULL)
+  if (hesiod_init (&context) < 0)
     return NSS_STATUS_UNAVAIL;
 
   list = hesiod_resolve (context, user, "grplist");
diff --git a/hesiod/nss_hesiod/hesiod-init.c b/hesiod/nss_hesiod/hesiod-init.c
deleted file mode 100644
index 2315040..0000000
--- a/hesiod/nss_hesiod/hesiod-init.c
+++ /dev/null
@@ -1,38 +0,0 @@
-/* Copyright (C) 2000-2016 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 2000.
-
-   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 <sys/cdefs.h>		/* Needs to come before <hesiod.h>.  */
-#include <hesiod.h>
-#include <resolv.h>
-#include <stddef.h>
-
-#include "nss_hesiod.h"
-
-void *
-_nss_hesiod_init (void)
-{
-  void *context;
-
-  if (hesiod_init (&context) == -1)
-    return NULL;
-
-  /* Use the default (per-thread) resolver state.  */
-  __hesiod_res_set (context, &_res, NULL);
-
-  return context;
-}
diff --git a/hesiod/nss_hesiod/hesiod-proto.c b/hesiod/nss_hesiod/hesiod-proto.c
index 3c59e73..8a13bba 100644
--- a/hesiod/nss_hesiod/hesiod-proto.c
+++ b/hesiod/nss_hesiod/hesiod-proto.c
@@ -25,8 +25,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "nss_hesiod.h"
-
 /* Declare a parser for Hesiod protocol entries.  Although the format
    of the entries is identical to those in /etc/protocols, here is no
    predefined parser for us to use.  */
@@ -68,8 +66,7 @@ lookup (const char *name, const char *type, struct protoent *proto,
   int found;
   int olderr = errno;
 
-  context = _nss_hesiod_init ();
-  if (context == NULL)
+  if (hesiod_init (&context) < 0)
     return NSS_STATUS_UNAVAIL;
 
   list = hesiod_resolve (context, name, type);
diff --git a/hesiod/nss_hesiod/hesiod-pwd.c b/hesiod/nss_hesiod/hesiod-pwd.c
index 1ddf3e3..c119167 100644
--- a/hesiod/nss_hesiod/hesiod-pwd.c
+++ b/hesiod/nss_hesiod/hesiod-pwd.c
@@ -24,8 +24,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "nss_hesiod.h"
-
 /* Get the declaration of the parser function.  */
 #define ENTNAME pwent
 #define STRUCTURE passwd
@@ -56,8 +54,7 @@ lookup (const char *name, const char *type, struct passwd *pwd,
   size_t len;
   int olderr = errno;
 
-  context = _nss_hesiod_init ();
-  if (context == NULL)
+  if (hesiod_init (&context) < 0)
     return NSS_STATUS_UNAVAIL;
 
   list = hesiod_resolve (context, name, type);
diff --git a/hesiod/nss_hesiod/hesiod-service.c b/hesiod/nss_hesiod/hesiod-service.c
index 756345f..2df9cbb 100644
--- a/hesiod/nss_hesiod/hesiod-service.c
+++ b/hesiod/nss_hesiod/hesiod-service.c
@@ -25,8 +25,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "nss_hesiod.h"
-
 /* Hesiod uses a format for service entries that differs from the
    traditional format.  We therefore declare our own parser.  */
 
@@ -69,8 +67,7 @@ lookup (const char *name, const char *type, const char *protocol,
   int found;
   int olderr = errno;
 
-  context = _nss_hesiod_init ();
-  if (context == NULL)
+  if (hesiod_init (&context) < 0)
     return NSS_STATUS_UNAVAIL;
 
   list = hesiod_resolve (context, name, type);
diff --git a/hesiod/nss_hesiod/nss_hesiod.h b/hesiod/nss_hesiod/nss_hesiod.h
deleted file mode 100644
index a6ed8ee..0000000
--- a/hesiod/nss_hesiod/nss_hesiod.h
+++ /dev/null
@@ -1,20 +0,0 @@
-/* Copyright (C) 2000-2016 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 2000.
-
-   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/>.  */
-
-/* Initialize a Hesiod context.  */
-extern void *_nss_hesiod_init (void);