glibc/resolv
Florian Weimer 20be978f05 resolv: Do not install libnss_dns.a, libnss_dns.so
Fixes commit e1fcf21474 ("resolv: Move nss_dns into libc").
2021-07-20 12:29:27 +02:00
..
arpa resolv: Deprecate legacy interfaces in libresolv 2021-07-19 07:55:42 +02:00
bits/types resolv: Introduce struct resolv_conf with extended resolver state 2017-07-03 20:57:28 +02:00
nss_dns resolv: Move nss_dns into libc 2021-07-19 07:56:57 +02:00
sys
tst-leaks2.root/etc Use libnss_files.so for tests posix/bug-ga2 and resolv/tst-leaks2 [BZ #26821] 2020-11-23 10:51:24 +01:00
base64.c Convert 703 function definitions to prototype style. 2015-10-16 20:21:49 +00:00
compat-gethnamaddr.c resolv: Move dn_expand to its own file and into libc 2021-07-19 07:56:21 +02:00
compat-hooks.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
Depend hurd: Add hurd thread library 2018-04-02 01:44:14 +02:00
dn_comp.c resolv: Move dn_comp to its own file and into libc 2021-07-19 07:56:21 +02:00
dn_expand.c resolv: Move dn_expand to its own file and into libc 2021-07-19 07:56:21 +02:00
dn_skipname.c resolv: Move dn_skipname to its own file and into libc 2021-07-19 07:56:21 +02:00
gai_cancel.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
gai_error.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
gai_misc.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
gai_misc.h resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
gai_notify.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
gai_sigqueue.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
gai_suspend.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
getaddrinfo_a.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
herror.c Consolidate non cancellable writev call 2017-08-21 15:37:45 -03:00
inet_addr.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
inet_net_ntop.c resolv: Remove SCCS and RCS keywords 2016-04-28 12:53:49 +02:00
inet_net_pton.c resolv: Remove SCCS and RCS keywords 2016-04-28 12:53:49 +02:00
inet_neta.c Consistently use uintN_t not u_intN_t everywhere. 2017-08-07 19:55:34 +00:00
inet_ntop.c resolv: Remove internal_function attribute 2017-08-31 16:07:52 +02:00
inet_pton.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
libanl-compat.c resolv: Move libanl into libc (if libpthread is in libc) 2021-07-02 11:45:00 +02:00
Makefile resolv: Do not install libnss_dns.a, libnss_dns.so 2021-07-20 12:29:27 +02:00
mapv4v6addr.h . 2007-07-31 13:33:18 +00:00
mapv4v6hostent.h Handle running out of buffer space with IPv6 mapping enabled. 2009-11-10 07:36:50 -08:00
netdb.h y2038: Add support for 64-bit time on legacy ABIs 2021-06-15 10:42:11 -03:00
ns_date.c Consistently use uintN_t not u_intN_t everywhere. 2017-08-07 19:55:34 +00:00
ns_makecanon.c resolv: Move ns_makecanon into its own file, and into libc 2021-07-19 07:56:21 +02:00
ns_name_compress.c resolv: Move ns_name_compress into its own file and into libc 2021-07-19 07:56:21 +02:00
ns_name_ntop.c resolv: Move ns_name_ntop to its own file and into libc 2021-07-15 08:39:31 +02:00
ns_name_pack.c resolv: Move ns_name_pack into its own file and into libc 2021-07-19 07:56:21 +02:00
ns_name_pton.c resolv: Move ns_name_pton into its own file and into libc 2021-07-19 07:56:21 +02:00
ns_name_skip.c resolv: Move ns_name_skip to its own file and into libc (bug 28091) 2021-07-19 07:56:13 +02:00
ns_name_uncompress.c resolv: Move ns_name_uncompress into its own file and into libc 2021-07-19 07:56:21 +02:00
ns_name_unpack.c resolv: Move ns_name_unpack to its own file and into libc 2021-07-15 09:00:27 +02:00
ns_name.c resolv: Move ns_name_compress into its own file and into libc 2021-07-19 07:56:21 +02:00
ns_netint.c resolv: Remove SCCS and RCS keywords 2016-04-28 12:53:49 +02:00
ns_parse.c resolv: Move dn_expand to its own file and into libc 2021-07-19 07:56:21 +02:00
ns_print.c resolv: Move ns_samename into its own file, and into libc 2021-07-19 07:56:21 +02:00
ns_samedomain.c resolv: Move ns_samename into its own file, and into libc 2021-07-19 07:56:21 +02:00
ns_samename.c resolv: Move ns_samename into its own file, and into libc 2021-07-19 07:56:21 +02:00
ns_ttl.c Add fall-through comments. 2019-02-12 10:30:34 +00:00
nsap_addr.c resolv: Remove SCCS and RCS keywords 2016-04-28 12:53:49 +02:00
nss_dns_functions.c nss: Directly load nss_dns, without going through dlsym/dlopen 2021-07-19 07:56:57 +02:00
README resolv: Remove unused resolv/res_debug.h header file 2017-06-30 11:31:29 +02:00
res_context_hostalias.c resolv: Move __res_context_hostalias into its own file and into libc 2021-07-19 07:56:21 +02:00
res_data.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
res_debug.c resolv: Move dn_expand to its own file and into libc 2021-07-19 07:56:21 +02:00
res_enable_icmp.c resolv: Move res_send, res_nsend into libc 2021-07-19 07:56:45 +02:00
res_get_nsaddr.c resolv: Move __res_get_nsaddr to its own file and into libc 2021-07-19 07:56:21 +02:00
res_hconf.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
res_hconf.h Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
res_hostalias.c resolv: Move res_hostalias into its own file, along with hostalias 2021-07-19 07:56:21 +02:00
res_init.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
res_isourserver.c resolv: Move res_isourserver to its own file and reformat to GNU style 2021-07-19 07:56:21 +02:00
res_libc.c Force building with -fno-common 2021-07-09 20:09:14 +02:00
res_mkquery.c resolv: Move res_mkquery, res_nmkquery into libc 2021-07-19 07:56:57 +02:00
res_nameinquery.c resolv: Move res_nameinquery to its own file and into libc 2021-07-19 07:56:21 +02:00
res_queriesmatch.c resolv: Move res_queriesmatch to its own file and into libc 2021-07-19 07:56:21 +02:00
res_query.c resolv: Move res_query functions into libc 2021-07-19 07:56:57 +02:00
res_randomid.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
res_send.c resolv: Move res_send, res_nsend into libc 2021-07-19 07:56:45 +02:00
res-close.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
res-name-checking.c resolv: Rename res_comp.c to res-name-checking.c and move into libc 2021-07-19 07:56:21 +02:00
res-putget.c resolv: Move _getlong, _getshort, __putlong, __putshort to res-putget 2021-07-19 07:56:21 +02:00
res-state.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
resolv_conf.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
resolv_conf.h Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
resolv_context.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
resolv_context.h Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
resolv-deprecated.c resolv: Move res_queriesmatch to its own file and into libc 2021-07-19 07:56:21 +02:00
resolv-internal.h resolv: Move res_query functions into libc 2021-07-19 07:56:57 +02:00
resolv.h resolv: Move res_query functions into libc 2021-07-19 07:56:57 +02:00
tst-aton.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-bug18665-tcp.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-bug18665.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-inet_aton_exact.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-inet_ntop.c Modify several tests to use test-skeleton.c 2014-11-05 15:24:08 +05:30
tst-inet_pton.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-leaks2.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-leaks.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-no-libidn2.c Switch IDNA implementation to libidn2 [BZ #19728] [BZ #19729] [BZ #22247] 2018-05-23 15:27:24 +02:00
tst-ns_name_compress.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-ns_name_pton.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-ns_name.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-ns_name.data Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-p_secstodate.c resolv: tst-p_secstodate can be a regular test 2021-03-09 21:07:24 +01:00
tst-res_hconf_reorder.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-res_hnok.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-ai_idn-common.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-ai_idn-latin1.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-ai_idn-nolibidn2.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-ai_idn.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-basic.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-binary.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-canonname.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-edns.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-network.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-nondecimal.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-qtypes.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-res_init-multi.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-res_init-skeleton.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-res_init-thread.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-res_init.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-res_ninit.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-rotate.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-search.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-threads.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-trailing.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-trustad.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
tst-resolv-txnid-collision.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
Versions resolv: Move nss_dns into libc 2021-07-19 07:56:57 +02:00

The resolver in the GNU C Library
*********************************

Starting with version 2.2, the resolver in the GNU C Library comes
from BIND 8.  Only a subset of the src/lib/resolv part of libbind is
included here; basically the parts that are needed to provide the
functionality present in the resolver from BIND 4.9.7 that was
included in the previous release of the GNU C Library, augmented by
the parts needed to provide thread-safety.  This means that support
for things as dynamic DNS updates and TSIG keys isn't included.  If
you need those facilities, please take a look at the full BIND
distribution.


Differences
===========

The resolver in the GNU C Library still differs from what's in BIND
8.2.3-T5B:

* The RES_DEBUG option (`options debug' in /etc/resolv.conf) has been
  disabled.

* The resolver in glibc allows underscores in domain names.

* The <resolv.h> header in glibc includes <netinet/in.h> and
  <arpa/nameser.h> to make it self-contained.

* The `res_close' function in glibc only tries to close open files
  referenced through `_res' if the RES_INIT bit is set in
  `_res.options'.  This fixes a potential security bug with programs
  that bogusly call `res_close' without initialising the resolver
  state first.  Note that the thread-safe `res_nclose' still doesn't
  check the RES_INIT bit.  By the way, you're not really supposed to
  call `res_close/res_nclose' directly.

* The resolver in glibc can connect to a nameserver over IPv6.  Just
  specify the IPv6 address in /etc/resolv.conf.  You cannot change the
  address of an IPv6 nameserver dynamically in your program though.


Using the resolver in multi-threaded code
=========================================

The traditional resolver interfaces `res_query', `res_search',
`res_mkquery', `res_send' and `res_init', used a static (global)
resolver state stored in the `_res' structure.  Therefore, these
interfaces are not thread-safe.  Therefore, BIND 8.2 introduced a set
of "new" interfaces `res_nquery', `res_nsearch', `res_nmkquery',
`res_nsend' and `res_ninit' that take a `res_state' as their first
argument, so you can use a per-thread resolver state.  In glibc, when
you link with -lpthread, such a per-thread resolver state is already
present.  It can be accessed using `_res', which has been redefined as
a macro, in a similar way to what has been done for the `errno' and
`h_errno' variables.  This per-thread resolver state is also used for
the `gethostby*' family of functions, which means that for example
`gethostbyname_r' is now fully thread-safe and re-entrant.  The
traditional resolver interfaces however, continue to use a single
resolver state and are therefore still thread-unsafe.  The resolver
state is the same resolver state that is used for the initial ("main")
thread.

This has the following consequences for existing binaries and source
code:

* Single-threaded programs will continue to work.  There should be no
  user-visible changes when you recompile them.

* Multi-threaded programs that use the traditional resolver interfaces
  in the "main" thread should continue to work, except that they no
  longer see any changes in the global resolver state caused by calls
  to, for example, `gethostbyname' in other threads.  Again there
  should be no user-visible changes when you recompile these programs.

* Multi-threaded programs that use the traditional resolver interfaces
  in more than one thread should be just as buggy as before (there are
  no problems if you use proper locking of course).  If you recompile
  these programs, manipulating the _res structure in threads other
  than the "main" thread will seem to have no effect though.

* In Multi-threaded that manipulate the _res structure, calls to
  functions like `gethostbyname' in threads other than the "main"
  thread won't be influenced by the those changes anymore.

We recommend to use the new thread-safe interfaces in new code, since
the traditional interfaces have been deprecated by the BIND folks.
For compatibility with other (older) systems you might want to
continue to use those interfaces though.


Using the resolver in C++ code
==============================

There resolver contains some hooks which will allow the user to
install some callback functions that make it possible to filter DNS
requests and responses.  Although we do not encourage you to make use
of this facility at all, C++ developers should realise that it isn't
safe to throw exceptions from such callback functions.


Source code
===========

The following files come from the BIND distribution (currently version
8.2.3-T5B):

src/include/
  arpa/nameser.h
  arpa/nameser_compat.h
  resolv.h

src/lib/resolv/
  herror.c
  res_comp.c
  res_data.c
  res_debug.c
  res_init.c
  res_mkquery.c
  res_query.c
  res_send.c

src/lib/nameser/
  ns_name.c
  ns_netint.c
  ns_parse.c
  ns_print.c
  ns_samedomain.c
  ns_ttl.c

src/lib/inet/
  inet_addr.c
  inet_net_ntop.c
  inet_net_pton.c
  inet_neta.c
  inet_ntop.c
  inet_pton.c
  nsap_addr.c

src/lib/isc/
  base64.c

Some of these files have been optimised a bit, and adaptations have
been made to make them fit in with the rest of glibc.

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.