44d8654a |
1 | |
88eae90a |
2 | GNU adns |
b1098573 |
3 | |
2e036093 |
4 | Advanced, easy to use, asynchronous-capable DNS client library and |
5 | utilities. |
b1098573 |
6 | |
aa958273 |
7 | adns is a resolver library for C (and C++) programs, and a collection |
4b84c25d |
8 | of useful DNS resolver utilities. |
b1098573 |
9 | |
4b84c25d |
10 | C 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. |
b1098573 |
41 | |
aa958273 |
42 | DNS 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. |
b1098573 |
57 | |
40180701 |
58 | Forthcoming: |
59 | |
60 | I hope that future versions may also have the following features: |
61 | * The library should be useable by threads in a multithreaded |
62 | program in a natural way. It should multiplex many threads' |
63 | queries through a single query socket. |
64 | * IPv6 support. |
65 | * Some kind of awareness of DNSSEC. |
66 | * Possibly some very limited caching behaviour. |
67 | * There was, at one point, a draft native Perl interface from Tony |
68 | Finch. |
69 | |
a2638561 |
70 | Documentation |
71 | |
72 | I'm afraid there is no manual yet. However, competent C programmers |
9a42a2c4 |
73 | should be able to use the library based on the [2]commented adns.h |
aa958273 |
74 | header file, and the usage messages for the programs should be |
75 | sufficient. |
b1098573 |
76 | |
4f3f9880 |
77 | Feedback |
78 | |
0db612f3 |
79 | I'd be pleased if you would let me know if you're using my library in |
80 | your project, and what you think of it. |
b1098573 |
81 | |
0db612f3 |
82 | If you are subscribed to adns-discuss please send feedback, including |
83 | bug reports, there; otherwise send mail to |
84 | adns-bugreports@chiark.greenend.org.uk. If you'd prefer that your |
85 | message wasn't forwarded to the adns-bugreports list, send it to |
aa958273 |
86 | adns-maint@chiark.greenend.org.uk. |
b1098573 |
87 | |
4f3f9880 |
88 | Mailinglists |
89 | |
90 | I have set up mailinglists adns-announce and adns-discuss. The |
91 | announcements list is moderated and will contain only announcements of |
9a42a2c4 |
92 | important bugs, new versions, etc. The bug reports address mentioned |
4f3f9880 |
93 | above is also a mailing list; feel free to subscribe to it. |
b1098573 |
94 | |
9a42a2c4 |
95 | There are [3]archives and subscription web pages, or you can subscribe |
4f3f9880 |
96 | by sending mail containing the word `subscribe' to |
97 | adns-announce-REQUEST@chiark.greenend.org.uk or |
98 | adns-discuss-REQUEST@chiark.greenend.org.uk. |
b1098573 |
99 | |
4f3f9880 |
100 | Download |
101 | |
9a42a2c4 |
102 | Available for download from [4]chiark.greenend.org.uk are: |
103 | * The [5]current release as a gzipped tarfile. |
104 | * [6]adns.h API header file with comments, and [7]usage message for |
4b84c25d |
105 | adnshost (currently there is no manual, sorry). |
9a42a2c4 |
106 | * All versions released so far are also available via [8]anonymous |
40180701 |
107 | FTP and [9]HTTP. |
108 | |
109 | You can also access the project CVS repositories: |
110 | * A mirror of the source code repository is available via rsync from |
88eae90a |
111 | rsync.chiark.greenend.org.uk::ftp/users/ian/cvs-pub/adns (use FTP |
9a42a2c4 |
112 | first to find your way around), or via [10]cvsweb. |
40180701 |
113 | * This web page is maintained in [11]Savannah, where you can browse |
114 | the [12]webpage CVS. |
b1098573 |
115 | |
40180701 |
116 | adns is also available from the [13]GNU Project FTP servers and their |
117 | [14]mirrors. |
b1098573 |
118 | |
9a42a2c4 |
119 | Technical note |
120 | |
40180701 |
121 | adns requires a real nameserver like [15]BIND or [16]Dents running on |
9a42a2c4 |
122 | the same system or a nearby one, which must be willing to provide |
123 | `recursive service'. I.e., adns is a `stub resolver'. All properly |
124 | configured UN*X and GNU systems will already have such nameserver(s); |
125 | they are usually listed in /etc/resolv.conf. |
b1098573 |
126 | |
127 | References and related projects |
128 | |
40180701 |
129 | There is a [17]port to MS Visual Studio 6 C++ by Jarle Aase. |
b1098573 |
130 | |
4f3f9880 |
131 | Copyright and licensing |
132 | |
40180701 |
133 | adns is Copyright 1997-2001 Ian Jackson, Copyright 1999-2000 Tony |
4b84c25d |
134 | Finch, and Copyright (C) 1991 Massachusetts Institute of Technology. |
b1098573 |
135 | |
4f3f9880 |
136 | adns is free software; you can redistribute it and/or modify it under |
137 | the terms of the GNU General Public License as published by the Free |
138 | Software Foundation; either version 2 of the License, or (at your |
139 | option) any later version. |
b1098573 |
140 | |
4f3f9880 |
141 | This program and documentation is distributed in the hope that it will |
142 | be useful, but without any warranty; without even the implied warranty |
a2638561 |
143 | of merchantability or fitness for a particular purpose. See the |
40180701 |
144 | [18]GNU General Public License for more details. |
b1098573 |
145 | |
4f3f9880 |
146 | You should have received a copy of the GNU General Public License |
147 | along with adns, or one should be available above; if not, write to |
40180701 |
148 | the [19]Free Software Foundation, 59 Temple Place - Suite 330, Boston, |
4f3f9880 |
149 | MA 02111-1307, USA, or email adns-maint@chiark.greenend.org.uk. |
150 | _________________________________________________________________ |
b1098573 |
151 | |
40180701 |
152 | [20]Ian Jackson / [21]adns-maint@chiark.greenend.org.uk; more [22]free |
4f3f9880 |
153 | software by me. |
b1098573 |
154 | |
40180701 |
155 | [23]GNU home page; [24]chiark home page; [25]site or mirror home page |
b1098573 |
156 | |
40180701 |
157 | This web page is Copyright (C)1996-2001 Ian Jackson. See the |
158 | [26]Copyright/acknowledgements. |
b1098573 |
159 | |
40180701 |
160 | Use any browser - [27]Campaign for a non-browser-specific WWW |
4f3f9880 |
161 | |
162 | References |
163 | |
9a42a2c4 |
164 | 1. http://www.chiark.greenend.org.uk/~ian/adns/adnshost.txt |
165 | 2. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.txt |
166 | 3. http://www.chiark.greenend.org.uk/mailman/listinfo |
167 | 4. http://www.chiark.greenend.org.uk/~ian/adns/ |
168 | 5. http://www.chiark.greenend.org.uk/~ian/adns/adns.tar.gz |
169 | 6. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.txt |
8a5e5147 |
170 | 7. http://www.chiark.greenend.org.uk/~ian/adns/adnshost.txt |
9a42a2c4 |
171 | 8. ftp://ftp.chiark.greenend.org.uk/users/ian/adns/ |
abf5f52c |
172 | 9. http://www.chiark.greenend.org.uk/~ian/adns/ftp/ |
9a42a2c4 |
173 | 10. http://www.chiark.greenend.org.uk/ucgi/~ijackson/cvsweb/adns/ |
40180701 |
174 | 11. http://savannah.gnu.org/ |
175 | 12. http://savannah.gnu.org/cgi-bin/viewcvs/software/adns/?cvsroot=www.gnu.org |
176 | 13. http://www.gnu.org/ |
177 | 14. http://www.gnu.org/order/ftp.html |
178 | 15. http://www.isc.org/view.cgi?/products/BIND/index.phtml |
179 | 16. http://www.dents.org/ |
180 | 17. http://adns.jgaa.com/ |
181 | 18. http://www.chiark.greenend.org.uk/~ian/COPYING.txt |
182 | 19. http://www.fsf.org/ |
183 | 20. http://www.chiark.greenend.org.uk/ |
184 | 21. mailto:adns-maint@chiark.greenend.org.uk |
185 | 22. http://www.chiark.greenend.org.uk/~ian/software/ |
186 | 23. http://www.gnu.org/ |
187 | 24. http://www.chiark.greenend.org.uk/ |
188 | 25. file://localhost/ |
189 | 26. http://www.chiark.greenend.org.uk/~ian/sw-www-copy.html |
190 | 27. http://www.anybrowser.org/campaign/ |