4 Advanced, easy to use, asynchronous-capable DNS client library.
6 adns is a resolver library for C (and C++) programs. In contrast with
7 the existing interfaces, gethostbyname et al and libresolv, it has the
9 * It is reasonably easy to use for simple programs which just want
10 to translate names to addresses, look up MX records, etc.
11 * It can be used in an asynchronous, non-blocking, manner. Many
12 queries can be handled simultaneously.
13 * Responses are decoded automatically into a natural representation
14 for a C program - there is no need to deal with DNS packet
16 * Sanity checking (eg, name syntax checking, reverse/forward
17 correspondence, CNAME pointing to CNAME) is performed
19 * Time-to-live, CNAME and other similar information is returned in
20 an easy-to-use form, without getting in the way.
21 * There is no global state in the library; resolver state is an
22 opaque data structure which the client creates explicitly. A
23 program can have several instances of the resolver.
24 * Errors are reported to the application in a way that distinguishes
25 the various causes of failure properly.
26 * Understands conventional resolv.conf, but this can overridden by
27 environment variables.
28 * Flexibility. For example, the application can tell adns to: ignore
29 environment variables (for setuid programs), disable sanity checks
30 eg to return arbitrary data, override or ignore resolv.conf in
31 favour of supplied configuration, etc.
32 * Believed to be correct ! For example, will correctly back off to
33 TCP in case of long replies or queries, or to other nameservers if
34 several are available. It has sensible handling of bad responses
39 I hope that future versions may also have the following features:
40 * The library will be useable by threads in a multithreaded program
41 in a natural way. It will multiplex many threads' queries through
42 a single query socket.
43 * Limited caching behaviour.
46 (Technical note: adns requires a real nameserver like BIND or [1]Dents
47 running on the same system or a nearby one, which must be willing to
48 provide `recursive service'. I.e., adns is a `stub resolver'. All
49 properly configured UN*X and GNU systems will already have such
50 nameserver(s); they are usually listed in /etc/resolv.conf.)
54 I'm afraid there is no manual yet. However, competent C programmers
55 should be able to use the library based on the commented [2]adns.h
56 header file (from version 0.1).
60 If you are subscribed to adns-discuss please send bug reports there;
61 otherwise mail them to adns-bugreports@chiark.greenend.org.uk.
65 I have set up mailinglists adns-announce and adns-discuss. The
66 announcements list is moderated and will contain only announcements of
67 important bugs, new versions, &c. The bug reports address mentioned
68 above is also a mailing list; feel free to subscribe to it.
70 There are [3]archives and subscription web pages, or you can subscribe
71 by sending mail containing the word `subscribe' to
72 adns-announce-REQUEST@chiark.greenend.org.uk or
73 adns-discuss-REQUEST@chiark.greenend.org.uk.
77 Available for download from [4]chiark.greenend.org.uk are:
78 * The [5]current pre-release version as a gzipped tarfile.
79 * [6]adns.h API header file with comments (currently there is no
81 * All versions released so far are also available via [7]anonymous
84 adns is also available from the [8]GNU Project FTP servers and their
87 Copyright and licensing
89 adns is Copyright 1997-1999 Ian Jackson.
91 adns is free software; you can redistribute it and/or modify it under
92 the terms of the GNU General Public License as published by the Free
93 Software Foundation; either version 2 of the License, or (at your
94 option) any later version.
96 This program and documentation is distributed in the hope that it will
97 be useful, but without any warranty; without even the implied warranty
98 of merchantability or fitness for a particular purpose. See the
99 [10]GNU General Public License for more details.
101 You should have received a copy of the GNU General Public License
102 along with adns, or one should be available above; if not, write to
103 the [11]Free Software Foundation, 59 Temple Place - Suite 330, Boston,
104 MA 02111-1307, USA, or email adns-maint@chiark.greenend.org.uk.
105 _________________________________________________________________
107 [12]Ian Jackson / [13]adns-maint@chiark.greenend.org.uk; more [14]free
110 [15]GNU home page; [16]chiark home page; [17]site or mirror home page
112 This web page is Copyright (C)1996-1999 Ian Jackson. See the
113 [18]Copyright/acknowledgements.
115 Use any browser - [19]Campaign for a non-browser-specific WWW
119 1. http://www.dents.org/
120 2. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.0.1.txt
121 3. http://www.chiark.greenend.org.uk/mailman/listinfo
122 4. http://www.chiark.greenend.org.uk/~ian/adns/
123 5. http://www.chiark.greenend.org.uk/~ian/adns/adns.tar.gz
124 6. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.0.1.txt
125 7. ftp://ftp.chiark.greenend.org.uk/users/ian/adns/
126 8. http://www.gnu.org/
127 9. http://www.gnu.org/order/ftp.html
128 10. http://www.chiark.greenend.org.uk/~ian/COPYING.txt
129 11. http://www.fsf.org/
130 12. http://www.chiark.greenend.org.uk/
131 13. mailto:adns-maint@chiark.greenend.org.uk
132 14. http://www.chiark.greenend.org.uk/~ian/software/
133 15. http://www.gnu.org/
134 16. http://www.chiark.greenend.org.uk/
135 17. http://www.chiark.greenend.org.uk/
136 18. http://www.chiark.greenend.org.uk/~ian/sw-www-copy.html
137 19. http://www.anybrowser.org/campaign/