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[adns] / README
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44d8654a 1
88eae90a 2 GNU adns
4f3f9880 3
2e036093 4 Advanced, easy to use, asynchronous-capable DNS client library and
5 utilities.
4f3f9880 6
aa958273 7 adns is a resolver library for C (and C++) programs, and a collection
4b84c25d 8 of useful DNS resolver utilities.
9
10C library
11
12 In contrast with the standard interfaces, gethostbyname et al and
13 libresolv, it has the following features:
44d8654a 14 * It is reasonably easy to use for simple programs which just want
15 to translate names to addresses, look up MX records, etc.
16 * It can be used in an asynchronous, non-blocking, manner. Many
17 queries can be handled simultaneously.
18 * Responses are decoded automatically into a natural representation
19 for a C program - there is no need to deal with DNS packet
20 formats.
21 * Sanity checking (eg, name syntax checking, reverse/forward
22 correspondence, CNAME pointing to CNAME) is performed
23 automatically.
24 * Time-to-live, CNAME and other similar information is returned in
4f3f9880 25 an easy-to-use form, without getting in the way.
44d8654a 26 * There is no global state in the library; resolver state is an
27 opaque data structure which the client creates explicitly. A
28 program can have several instances of the resolver.
29 * Errors are reported to the application in a way that distinguishes
30 the various causes of failure properly.
31 * Understands conventional resolv.conf, but this can overridden by
32 environment variables.
33 * Flexibility. For example, the application can tell adns to: ignore
aa958273 34 environment variables (for setuid programs), disable hostname
35 syntax sanity checks to return arbitrary data, override or ignore
36 resolv.conf in favour of supplied configuration, etc.
44d8654a 37 * Believed to be correct ! For example, will correctly back off to
38 TCP in case of long replies or queries, or to other nameservers if
39 several are available. It has sensible handling of bad responses
40 etc.
4f3f9880 41
aa958273 42DNS utility programs
43
2e036093 44 adns also comes with a number of utility programs for use from the
45 command line and in scripts:
46 * adnslogres is a much faster version of Apache's logresolv program.
47 * adnsresfilter is a filter which copies its input to its output,
48 replacing IP addresses by the corresponding names, without unduly
49 delaying the output. For example, you can usefully pipe the output
50 of netstat -n, tcpdump -ln, and the like, into it.
51 * adnshost is a general-purpose DNS lookup utility which can be used
aa958273 52 easily in from the command line and from shell scripts to do
53 simple lookups. In a more advanced mode it can be used as a
54 general-purpose DNS helper program for scripting languages which
9a42a2c4 55 can invoke and communicate with subprocesses. See the [1]adnshost
56 usage message for a summary of its capabilities.
2e036093 57
a2638561 58Documentation
59
60 I'm afraid there is no manual yet. However, competent C programmers
9a42a2c4 61 should be able to use the library based on the [2]commented adns.h
aa958273 62 header file, and the usage messages for the programs should be
63 sufficient.
4f3f9880 64
65Feedback
66
0db612f3 67 I'd be pleased if you would let me know if you're using my library in
68 your project, and what you think of it.
69
70 If you are subscribed to adns-discuss please send feedback, including
71 bug reports, there; otherwise send mail to
72 adns-bugreports@chiark.greenend.org.uk. If you'd prefer that your
73 message wasn't forwarded to the adns-bugreports list, send it to
aa958273 74 adns-maint@chiark.greenend.org.uk.
4f3f9880 75
76Mailinglists
77
78 I have set up mailinglists adns-announce and adns-discuss. The
79 announcements list is moderated and will contain only announcements of
9a42a2c4 80 important bugs, new versions, etc. The bug reports address mentioned
4f3f9880 81 above is also a mailing list; feel free to subscribe to it.
82
9a42a2c4 83 There are [3]archives and subscription web pages, or you can subscribe
4f3f9880 84 by sending mail containing the word `subscribe' to
85 adns-announce-REQUEST@chiark.greenend.org.uk or
86 adns-discuss-REQUEST@chiark.greenend.org.uk.
87
88Download
89
9a42a2c4 90 Available for download from [4]chiark.greenend.org.uk are:
91 * The [5]current release as a gzipped tarfile.
92 * [6]adns.h API header file with comments, and [7]usage message for
4b84c25d 93 adnshost (currently there is no manual, sorry).
9a42a2c4 94 * All versions released so far are also available via [8]anonymous
95 FTP and [9]HTTP,
88eae90a 96 * A mirror of my CVS repository is available via rsync from
97 rsync.chiark.greenend.org.uk::ftp/users/ian/cvs-pub/adns (use FTP
9a42a2c4 98 first to find your way around), or via [10]cvsweb.
4f3f9880 99
9a42a2c4 100 adns is also available from the [11]GNU Project FTP servers and their
101 [12]mirrors.
102
103Technical note
104
105 adns requires a real nameserver like [13]BIND or [14]Dents running on
106 the same system or a nearby one, which must be willing to provide
107 `recursive service'. I.e., adns is a `stub resolver'. All properly
108 configured UN*X and GNU systems will already have such nameserver(s);
109 they are usually listed in /etc/resolv.conf.
4f3f9880 110
111Copyright and licensing
112
4b84c25d 113 adns is Copyright 1997-2000 Ian Jackson, Copyright 1999-2000 Tony
114 Finch, and Copyright (C) 1991 Massachusetts Institute of Technology.
4f3f9880 115
116 adns is free software; you can redistribute it and/or modify it under
117 the terms of the GNU General Public License as published by the Free
118 Software Foundation; either version 2 of the License, or (at your
119 option) any later version.
120
121 This program and documentation is distributed in the hope that it will
122 be useful, but without any warranty; without even the implied warranty
a2638561 123 of merchantability or fitness for a particular purpose. See the
4b84c25d 124 [15]GNU General Public License for more details.
4f3f9880 125
126 You should have received a copy of the GNU General Public License
127 along with adns, or one should be available above; if not, write to
4b84c25d 128 the [16]Free Software Foundation, 59 Temple Place - Suite 330, Boston,
4f3f9880 129 MA 02111-1307, USA, or email adns-maint@chiark.greenend.org.uk.
130 _________________________________________________________________
131
4b84c25d 132 [17]Ian Jackson / [18]adns-maint@chiark.greenend.org.uk; more [19]free
4f3f9880 133 software by me.
134
4b84c25d 135 [20]GNU home page; [21]chiark home page; [22]site or mirror home page
4f3f9880 136
89435c42 137 This web page is Copyright (C)1996-2000 Ian Jackson. See the
4b84c25d 138 [23]Copyright/acknowledgements.
4f3f9880 139
4b84c25d 140 Use any browser - [24]Campaign for a non-browser-specific WWW
4f3f9880 141
142References
143
9a42a2c4 144 1. http://www.chiark.greenend.org.uk/~ian/adns/adnshost.txt
145 2. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.txt
146 3. http://www.chiark.greenend.org.uk/mailman/listinfo
147 4. http://www.chiark.greenend.org.uk/~ian/adns/
148 5. http://www.chiark.greenend.org.uk/~ian/adns/adns.tar.gz
149 6. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.txt
150 7. http://www.chiark.greenend.org.uk/~ian/adns/adnsresfilter.txt
151 8. ftp://ftp.chiark.greenend.org.uk/users/ian/adns/
152 9. http://www.chiark.greenend.org.uk/~/ian/adns/ftp/
153 10. http://www.chiark.greenend.org.uk/ucgi/~ijackson/cvsweb/adns/
154 11. http://www.gnu.org/
155 12. http://www.gnu.org/order/ftp.html
156 13. http://www.isc.org/view.cgi?/products/BIND/index.phtml
157 14. http://www.dents.org/
4b84c25d 158 15. http://www.chiark.greenend.org.uk/~ian/COPYING.txt
159 16. http://www.fsf.org/
160 17. http://www.chiark.greenend.org.uk/
161 18. mailto:adns-maint@chiark.greenend.org.uk
162 19. http://www.chiark.greenend.org.uk/~ian/software/
163 20. http://www.gnu.org/
164 21. http://www.chiark.greenend.org.uk/
165 22. file://localhost/
166 23. http://www.chiark.greenend.org.uk/~ian/sw-www-copy.html
167 24. http://www.anybrowser.org/campaign/