resolv: Remove unsupported hook functions from the API [BZ #20016]

ChangeLog

@@ -1,3 +1,18 @@
+2016-09-21  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #20016]
+	* resolv/res_send.c (__libc_res_nsend): Remove USE_HOOK code.
+	* resolv/res_data.c (res_send_setqhook, res_send_setrhook):
+	Move ...
+	* resolv/compat-hooks.c (res_send_setqhook, res_send_setrhook):
+	... here, as compatibility symbols in a new file.
+	* resolv/Makefile (libresolv-routines): Add compat-hooks.
+	* resolv/res_init.c (__res_vinit): Adjust member names.
+	* include/resolv.h (res_send_setqhook, res_send_setrhook): Remove.
+	* resolv/resolv.h (res_sendhookact, res_send_qhook)
+	(res_send_rhook): Remove.
+	(struct __res_state): Rename qhook, rhook members.
+
 2016-09-21  Florian Weimer  <fweimer@redhat.com>
 
 	malloc: Use __libc_lock wrappers.

NEWS

@@ -56,6 +56,11 @@ Version 2.25
   meta-RR types is not officially standardized, subject to revision, and
   thus not suitable for encoding in a macro.
 
+* The types res_sendhookact, res_send_qhook, re_send_rhook, and the qhook
+  and rhook members of the res_state type in <resolv.h> have been removed.
+  The glibc stub resolver did not support these hooks, but the header file
+  did not reflect that.
+
 Security related changes:
 
   On ARM EABI (32-bit), generating a backtrace for execution contexts which

include/resolv.h

@@ -33,8 +33,6 @@ extern u_int32_t _getlong (const u_char *__src);
 extern u_int16_t _getshort (const u_char *__src);
 extern void res_pquery (const res_state __statp, const u_char *__msg,
 			int __len, FILE *__file);
-extern void res_send_setqhook (res_send_qhook __hook);
-extern void res_send_setrhook (res_send_rhook __hook);
 extern int res_ourserver_p (const res_state __statp,
 			    const struct sockaddr_in6 *__inp);
 extern void __res_iclose (res_state statp, bool free_addr);

resolv/Makefile

@@ -46,7 +46,7 @@ libresolv-routines := gethnamaddr res_comp res_debug	\
 		      res_data res_mkquery res_query res_send		\
 		      inet_net_ntop inet_net_pton inet_neta base64	\
 		      ns_parse ns_name ns_netint ns_ttl ns_print	\
-		      ns_samedomain ns_date
+		      ns_samedomain ns_date compat-hooks
 
 libanl-routines := gai_cancel gai_error gai_misc gai_notify gai_suspend \
 		   getaddrinfo_a

resolv/compat-hooks.c

@@ -0,0 +1,56 @@
+/* Compatibility functions for obsolete libresolv hooks.
+   Copyright (C) 1999-2016 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) 1995-1999 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 <resolv.h>
+
+#include <shlib-compat.h>
+
+#if SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_25)
+
+void
+attribute_compat_text_section
+res_send_setqhook(void *hook) {
+  _res.__glibc_unused_qhook = hook;
+}
+compat_symbol (libresolv, res_send_setqhook, res_send_setqhook, GLIBC_2_0);
+
+void
+attribute_compat_text_section
+res_send_setrhook(void *hook) {
+  _res.__glibc_unused_rhook = hook;
+}
+compat_symbol (libresolv, res_send_setrhook, res_send_setrhook, GLIBC_2_0);
+
+#endif

resolv/res_data.c

@@ -104,16 +104,6 @@ res_query(const char *name,	/* domain name */
 	return (res_nquery(&_res, name, class, type, answer, anslen));
 }
 
-void
-res_send_setqhook(res_send_qhook hook) {
-	_res.qhook = hook;
-}
-
-void
-res_send_setrhook(res_send_rhook hook) {
-	_res.rhook = hook;
-}
-
 int
 res_isourserver(const struct sockaddr_in *inp) {
 	return (res_ourserver_p(&_res, (const struct sockaddr_in6 *) inp));

resolv/res_init.c

@@ -144,8 +144,8 @@ __res_vinit(res_state statp, int preinit) {
 	statp->pfcode = 0;
 	statp->_vcsock = -1;
 	statp->_flags = 0;
-	statp->qhook = NULL;
+	statp->__glibc_unused_qhook = NULL;
-	statp->rhook = NULL;
+	statp->__glibc_unused_rhook = NULL;
 	statp->_u._ext.nscount = 0;
 	for (n = 0; n < MAXNS; n++)
 	    statp->_u._ext.nsaddrs[n] = NULL;

resolv/res_send.c

@@ -364,22 +364,6 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen,
 		return (-1);
 	}
 
-#ifdef USE_HOOKS
-	if (__glibc_unlikely (statp->qhook || statp->rhook))       {
-		if (anssiz < MAXPACKET && ansp) {
-			/* Always allocate MAXPACKET, callers expect
-			   this specific size.  */
-			u_char *buf = malloc (MAXPACKET);
-			if (buf == NULL)
-				return (-1);
-			memcpy (buf, ans, HFIXEDSZ);
-			*ansp = buf;
-			ans = buf;
-			anssiz = MAXPACKET;
-		}
-	}
-#endif
-
 	DprintQ((statp->options & RES_DEBUG) || (statp->pfcode & RES_PRF_QUERY),
 		(stdout, ";; res_send()\n"), buf, buflen);
 	v_circuit = ((statp->options & RES_USEVC)
@@ -468,47 +452,10 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen,
 	    {
 #ifdef DEBUG
 		char tmpbuf[40];
-#endif
-#if defined USE_HOOKS || defined DEBUG
 		struct sockaddr *nsap = get_nsaddr (statp, ns);
 #endif
 
 	    same_ns:
-#ifdef USE_HOOKS
-		if (__glibc_unlikely (statp->qhook != NULL))       {
-			int done = 0, loops = 0;
-
-			do {
-				res_sendhookact act;
-
-				struct sockaddr_in *nsap4;
-				nsap4 = (struct sockaddr_in *) nsap;
-				act = (*statp->qhook)(&nsap4, &buf, &buflen,
-						      ans, anssiz, &resplen);
-				nsap = (struct sockaddr_in6 *) nsap4;
-				switch (act) {
-				case res_goahead:
-					done = 1;
-					break;
-				case res_nextns:
-					__res_iclose(statp, false);
-					goto next_ns;
-				case res_done:
-					return (resplen);
-				case res_modified:
-					/* give the hook another try */
-					if (++loops < 42) /*doug adams*/
-						break;
-					/*FALLTHROUGH*/
-				case res_error:
-					/*FALLTHROUGH*/
-				default:
-					return (-1);
-				}
-			} while (!done);
-		}
-#endif
-
 		Dprint(statp->options & RES_DEBUG,
 		       (stdout, ";; Querying server (# %d) address = %s\n",
 			ns + 1, inet_ntop(nsap->sa_family,
@@ -571,38 +518,6 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen,
 		    (statp->options & RES_STAYOPEN) == 0) {
 			__res_iclose(statp, false);
 		}
-#ifdef USE_HOOKS
-		if (__glibc_unlikely (statp->rhook))       {
-			int done = 0, loops = 0;
-
-			do {
-				res_sendhookact act;
-
-				act = (*statp->rhook)((struct sockaddr_in *)
-						      nsap, buf, buflen,
-						      ans, anssiz, &resplen);
-				switch (act) {
-				case res_goahead:
-				case res_done:
-					done = 1;
-					break;
-				case res_nextns:
-					__res_iclose(statp, false);
-					goto next_ns;
-				case res_modified:
-					/* give the hook another try */
-					if (++loops < 42) /*doug adams*/
-						break;
-					/*FALLTHROUGH*/
-				case res_error:
-					/*FALLTHROUGH*/
-				default:
-					return (-1);
-				}
-			} while (!done);
-
-		}
-#endif
 		return (resplen);
  next_ns: ;
 	   } /*foreach ns*/

resolv/resolv.h

@@ -68,23 +68,6 @@
 #ifndef __res_state_defined
 # define __res_state_defined
 
-typedef enum { res_goahead, res_nextns, res_modified, res_done, res_error }
-	res_sendhookact;
-
-typedef res_sendhookact (*res_send_qhook) (struct sockaddr_in * const *__ns,
-					   const u_char **__query,
-					   int *__querylen,
-					   u_char *__ans,
-					   int __anssiz,
-					   int *__resplen);
-
-typedef res_sendhookact (*res_send_rhook) (const struct sockaddr_in *__ns,
-					   const u_char *__query,
-					   int __querylen,
-					   u_char *__ans,
-					   int __anssiz,
-					   int *__resplen);
-
 /*
  * Global defines and variables for resolver stub.
  */
@@ -123,8 +106,8 @@ struct __res_state {
 		u_int32_t	mask;
 	} sort_list[MAXRESOLVSORT];
 	/* 4 byte hole here on 64-bit architectures.  */
-	res_send_qhook qhook;		/* query hook */
+	void * __glibc_unused_qhook;
-	res_send_rhook rhook;		/* response hook */
+	void * __glibc_unused_rhook;
 	int	res_h_errno;		/* last one set for this context */
 	int	_vcsock;		/* PRIVATE: for res_send VC i/o */
 	u_int	_flags;			/* PRIVATE: see below */