chiark / gitweb /
finalise 0.5
[adns] / README
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44d8654a 1
4f3f9880 2 adns
3
44d8654a 4 Advanced, easy to use, asynchronous-capable DNS client library.
4f3f9880 5
44d8654a 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
8 following features:
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
15 formats.
16 * Sanity checking (eg, name syntax checking, reverse/forward
17 correspondence, CNAME pointing to CNAME) is performed
18 automatically.
19 * Time-to-live, CNAME and other similar information is returned in
4f3f9880 20 an easy-to-use form, without getting in the way.
44d8654a 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
4f3f9880 31 favour of supplied configuration, etc.
44d8654a 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
35 etc.
4f3f9880 36
44d8654a 37Forthcoming:
4f3f9880 38
44d8654a 39 I hope that future versions may also have the following features:
0db612f3 40 * The library should be useable by threads in a multithreaded
41 program in a natural way. It should multiplex many threads'
42 queries through a single query socket.
44d8654a 43 * IPv6 support.
0db612f3 44 * Some kind of awareness of DNSSEC.
45 * Possibly some very limited caching behaviour.
4f3f9880 46
a2638561 47 (Technical note: adns requires a real nameserver like BIND or [1]Dents
48 running on the same system or a nearby one, which must be willing to
49 provide `recursive service'. I.e., adns is a `stub resolver'. All
50 properly configured UN*X and GNU systems will already have such
51 nameserver(s); they are usually listed in /etc/resolv.conf.)
52
53Documentation
54
55 I'm afraid there is no manual yet. However, competent C programmers
56 should be able to use the library based on the commented [2]adns.h
0db612f3 57 header file (from version 0.3).
4f3f9880 58
59Feedback
60
0db612f3 61 I'd be pleased if you would let me know if you're using my library in
62 your project, and what you think of it.
63
64 If you are subscribed to adns-discuss please send feedback, including
65 bug reports, there; otherwise send mail to
66 adns-bugreports@chiark.greenend.org.uk. If you'd prefer that your
67 message wasn't forwarded to the adns-bugreports list, send it to
68 adns-maint@chiark.greendend.org.uk.
4f3f9880 69
70Mailinglists
71
72 I have set up mailinglists adns-announce and adns-discuss. The
73 announcements list is moderated and will contain only announcements of
74 important bugs, new versions, &c. The bug reports address mentioned
75 above is also a mailing list; feel free to subscribe to it.
76
a2638561 77 There are [3]archives and subscription web pages, or you can subscribe
4f3f9880 78 by sending mail containing the word `subscribe' to
79 adns-announce-REQUEST@chiark.greenend.org.uk or
80 adns-discuss-REQUEST@chiark.greenend.org.uk.
81
82Download
83
a2638561 84 Available for download from [4]chiark.greenend.org.uk are:
85 * The [5]current pre-release version as a gzipped tarfile.
86 * [6]adns.h API header file with comments (currently there is no
87 manual, sorry).
88 * All versions released so far are also available via [7]anonymous
89 FTP.
4f3f9880 90
a2638561 91 adns is also available from the [8]GNU Project FTP servers and their
92 [9]mirrors.
4f3f9880 93
94Copyright and licensing
95
96 adns is Copyright 1997-1999 Ian Jackson.
97
98 adns is free software; you can redistribute it and/or modify it under
99 the terms of the GNU General Public License as published by the Free
100 Software Foundation; either version 2 of the License, or (at your
101 option) any later version.
102
103 This program and documentation is distributed in the hope that it will
104 be useful, but without any warranty; without even the implied warranty
a2638561 105 of merchantability or fitness for a particular purpose. See the
106 [10]GNU General Public License for more details.
4f3f9880 107
108 You should have received a copy of the GNU General Public License
109 along with adns, or one should be available above; if not, write to
a2638561 110 the [11]Free Software Foundation, 59 Temple Place - Suite 330, Boston,
4f3f9880 111 MA 02111-1307, USA, or email adns-maint@chiark.greenend.org.uk.
112 _________________________________________________________________
113
a2638561 114 [12]Ian Jackson / [13]adns-maint@chiark.greenend.org.uk; more [14]free
4f3f9880 115 software by me.
116
a2638561 117 [15]GNU home page; [16]chiark home page; [17]site or mirror home page
4f3f9880 118
119 This web page is Copyright (C)1996-1999 Ian Jackson. See the
a2638561 120 [18]Copyright/acknowledgements.
4f3f9880 121
a2638561 122 Use any browser - [19]Campaign for a non-browser-specific WWW
4f3f9880 123
124References
125
a2638561 126 1. http://www.dents.org/
0db612f3 127 2. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.0.3.txt
a2638561 128 3. http://www.chiark.greenend.org.uk/mailman/listinfo
129 4. http://www.chiark.greenend.org.uk/~ian/adns/
130 5. http://www.chiark.greenend.org.uk/~ian/adns/adns.tar.gz
0db612f3 131 6. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.0.3.txt
a2638561 132 7. ftp://ftp.chiark.greenend.org.uk/users/ian/adns/
133 8. http://www.gnu.org/
134 9. http://www.gnu.org/order/ftp.html
135 10. http://www.chiark.greenend.org.uk/~ian/COPYING.txt
136 11. http://www.fsf.org/
137 12. http://www.chiark.greenend.org.uk/
138 13. mailto:adns-maint@chiark.greenend.org.uk
139 14. http://www.chiark.greenend.org.uk/~ian/software/
140 15. http://www.gnu.org/
141 16. http://www.chiark.greenend.org.uk/
142 17. http://www.chiark.greenend.org.uk/
143 18. http://www.chiark.greenend.org.uk/~ian/sw-www-copy.html
144 19. http://www.anybrowser.org/campaign/