| 1 | <html><head><title>adns - advanced, alternative, asynchronous resolver</title> |
| 2 | <link rev="made" href="mailto:adns-maint@chiark.greenend.org.uk"> |
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| 4 | </head> |
| 5 | <body> |
| 6 | <h1>GNU adns</h1> |
| 7 | |
| 8 | <strong>Advanced, easy to use, asynchronous-capable DNS client |
| 9 | library and utilities.</strong> |
| 10 | |
| 11 | <!-- Note: this file must contain portable HTML ! --> |
| 12 | <!-- --> |
| 13 | <!-- It is served on the GNU site and also from my own system, --> |
| 14 | <!-- under the URL http://www.chiark.greenend.org.uk/adns/ --> |
| 15 | <!-- Please ensure that all links continine to be correct --> |
| 16 | <!-- both for www.gnu.org and chiark. --> |
| 17 | <!-- --> |
| 18 | |
| 19 | <p> |
| 20 | |
| 21 | adns is a resolver library for C (and C++) programs, and a collection |
| 22 | of useful DNS resolver utilities. |
| 23 | |
| 24 | |
| 25 | <h2>C library</h2> |
| 26 | |
| 27 | In contrast with the standard interfaces, gethostbyname et al and |
| 28 | libresolv, it has the following features: |
| 29 | |
| 30 | <ul> |
| 31 | |
| 32 | <li>It is reasonably easy to use for simple programs which just want |
| 33 | to translate names to addresses, look up MX records, etc. |
| 34 | |
| 35 | <li>It can be used in an asynchronous, non-blocking, manner. Many |
| 36 | queries can be handled simultaneously. |
| 37 | |
| 38 | <li>Responses are decoded automatically into a natural representation |
| 39 | for a C program - there is no need to deal with DNS packet and RRDATA |
| 40 | formats. |
| 41 | |
| 42 | <li>Sanity checking (eg, name syntax checking, reverse/forward |
| 43 | correspondence, CNAME pointing to CNAME) is performed automatically |
| 44 | by default. |
| 45 | |
| 46 | <li>Time-to-live, CNAME and other similar information is returned in |
| 47 | an easy-to-use form, without getting in the way. |
| 48 | |
| 49 | <li>There is no global state in the library; resolver state is an |
| 50 | opaque data structure which the client creates explicitly. A program |
| 51 | can have several instances of the resolver. |
| 52 | |
| 53 | <li>Errors are reported to the application in a way that distinguishes |
| 54 | the various causes of failure properly. |
| 55 | |
| 56 | <li>adns understands conventional resolv.conf, but this can overridden |
| 57 | by environment variables. |
| 58 | |
| 59 | <li>Flexibility. For example, the application can tell adns to: |
| 60 | ignore environment variables (for setuid programs), disable hostname |
| 61 | syntax sanity checks to return arbitrary data, override or ignore |
| 62 | resolv.conf in favour of supplied configuration, etc. |
| 63 | |
| 64 | <li>Believed to be correct ! For example, will correctly back off to |
| 65 | TCP in case of long replies or queries, or to other nameservers if |
| 66 | several are available. It has sensible handling of bad responses etc. |
| 67 | |
| 68 | </ul> |
| 69 | |
| 70 | <h2>DNS utility programs</h2> |
| 71 | |
| 72 | adns also comes with a number of utility programs for use from the |
| 73 | command line and in scripts: |
| 74 | |
| 75 | <ul> |
| 76 | |
| 77 | <li><code>adnslogres</code> is a much faster version of Apache's |
| 78 | logresolv program. |
| 79 | |
| 80 | <li><code>adnsresfilter</code> is a filter which copies its input to |
| 81 | its output, replacing IP addresses by the corresponding names, without |
| 82 | unduly delaying the output. For example, you can usefully pipe the |
| 83 | output of netstat -n, tcpdump -ln, and the like, into it. |
| 84 | |
| 85 | <li><code>adnshost</code> is a general-purpose DNS lookup utility |
| 86 | which can be used easily in from the command line and from shell |
| 87 | scripts to do simple lookups. In a more advanced mode it can be used |
| 88 | as a general-purpose DNS helper program for scripting languages which |
| 89 | can invoke and communicate with subprocesses. See the |
| 90 | <A href="http://www.chiark.greenend.org.uk/~ian/adns/docs/adnshost.txt">adnshost |
| 91 | usage message</A> for a summary of its capabilities. |
| 92 | |
| 93 | </ul> |
| 94 | |
| 95 | <h2>Documentation</h2> |
| 96 | |
| 97 | I'm afraid there is no manual yet. However, competent C programmers |
| 98 | should be able to use the library based on the |
| 99 | <A href="http://www.chiark.greenend.org.uk/~ian/adns/docs/adns.h.txt">commented |
| 100 | adns.h header file</A>, and the usage messages for the programs should |
| 101 | be sufficient. |
| 102 | |
| 103 | <h2>Feedback</h2> |
| 104 | |
| 105 | I'd be pleased if you would let me know if you're using my library in |
| 106 | your project, and what you think of it. |
| 107 | |
| 108 | <p> |
| 109 | |
| 110 | Bug reports should be reported to the |
| 111 | <a href="http://debbugs.gnu.org/">GNU Debbugs</a>. Send an email |
| 112 | to <code>submit@debbugs.gnu.org</code> and at the top of your email, |
| 113 | in a paragraph of its own, write the single line |
| 114 | <pre> |
| 115 | Package: adns |
| 116 | </pre> |
| 117 | Your bug report will be published via to the adns-discuss list. |
| 118 | |
| 119 | <p> |
| 120 | |
| 121 | Feedback and discussion takes place on the <code>adns-discuss</code> |
| 122 | list. You can mail me privately |
| 123 | at <code>ijackson@chiark.greenend.org.uk</code>. |
| 124 | |
| 125 | <h2>Mailinglists</h2> |
| 126 | |
| 127 | I have set up mailinglists <code>adns-announce</code> and |
| 128 | <code>adns-discuss</code>. The announcements list is moderated and |
| 129 | will contain only announcements of important bugs, new versions, etc. |
| 130 | |
| 131 | <p> |
| 132 | |
| 133 | There are |
| 134 | <A href="http://www.chiark.greenend.org.uk/mailman/listinfo">archives |
| 135 | and subscription web pages</A>, or you can subscribe by sending mail |
| 136 | containing the word `subscribe' to |
| 137 | <code>adns-announce-REQUEST@chiark.greenend.org.uk</code> or |
| 138 | <code>adns-discuss-REQUEST@chiark.greenend.org.uk</code>. |
| 139 | |
| 140 | <h2>Documentation</h2> |
| 141 | |
| 142 | <ul> |
| 143 | <li><A href="http://www.chiark.greenend.org.uk/~ian/adns/docs/adns.h.txt">adns.h |
| 144 | API header file with documentation comments</A> |
| 145 | <li><A href="http://www.chiark.greenend.org.uk/~ian/adns/docs/adnshost.txt">usage |
| 146 | message for adnshost</A> |
| 147 | </ul> |
| 148 | |
| 149 | <h2>Download and source code</h2> |
| 150 | |
| 151 | <ul> |
| 152 | <li>The <A href="http://www.chiark.greenend.org.uk/~ian/adns/adns.tar.gz">current |
| 153 | release</A> as a gzipped tarfile. |
| 154 | <li><A href="http://www.chiark.greenend.org.uk/~ian/adns/ftp/">Previous |
| 155 | versions</A> and other files (including OpenPGP signatures). |
| 156 | <li><A href="http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git/adns.git/">master |
| 157 | git (version control) repository browser</a>. |
| 158 | </ul> |
| 159 | |
| 160 | adns is also available from the |
| 161 | <A href="http://www.gnu.org/">GNU Project</A> FTP servers and their |
| 162 | <A href="http://www.gnu.org/order/ftp.html">mirrors</A>. |
| 163 | |
| 164 | <h2>Installation note</h2> |
| 165 | |
| 166 | adns requires a real nameserver like BIND running on the same system |
| 167 | or a nearby one, which must be willing to provide `recursive service'. |
| 168 | I.e., adns is a `stub resolver'. |
| 169 | |
| 170 | <p> |
| 171 | adns requires that your real nameserver is on the same machine, or |
| 172 | connected via a secure network, so that an attacker cannot fake the |
| 173 | replies to adns's queries. |
| 174 | |
| 175 | <h2>References and related projects</h2> |
| 176 | |
| 177 | <ul> |
| 178 | <li><a href="http://code.google.com/p/adns-python">Python bindings</a> |
| 179 | by Andy Dustman. |
| 180 | <!-- <li><a href="http://cryp.to/hsdns/">Haskell bindings</a> |
| 181 | by Peter Simons. --> |
| 182 | <li><a href="http://www.lysator.liu.se/liboop/">liboop event loop library</a> |
| 183 | has a built-in binding for adns. |
| 184 | <li><a href="http://adns.jgaa.com/">port to MS Visual Studio 6 C++</a> |
| 185 | by Jarle Aase. |
| 186 | </ul> |
| 187 | |
| 188 | <h2>Copyright and licensing</h2> |
| 189 | |
| 190 | <kbd>adns</kbd> is Copyright 1997-2000,2003,2006,2014 Ian Jackson, |
| 191 | Copyright 2014 Mark Wooding, Copyright 1999-2000,2003,2006 Tony Finch, |
| 192 | and Copyright (C) 1991 Massachusetts Institute of Technology. |
| 193 | |
| 194 | <p> |
| 195 | |
| 196 | <kbd>adns</kbd> is free software; you can redistribute it and/or modify |
| 197 | it under the terms of the GNU General Public License as published by |
| 198 | the Free Software Foundation; either version 3 of the License, or (at |
| 199 | your option) any later version. |
| 200 | |
| 201 | <p> |
| 202 | |
| 203 | This program and documentation is distributed in the hope that it will |
| 204 | be useful, but <em>without any warranty</em>; without even the implied |
| 205 | warranty of <em>merchantability</em> or <em>fitness for a particular |
| 206 | purpose</em>. See the |
| 207 | <A href="http://www.chiark.greenend.org.uk/~ian/adns/docs/COPYING.txt">GNU |
| 208 | General Public License</A> for more details. |
| 209 | |
| 210 | <p> |
| 211 | |
| 212 | You should have received a copy of the GNU General Public License |
| 213 | along with <kbd>adns</kbd>, or one should be available above; if not, |
| 214 | write to the <A href="http://www.fsf.org/">Free Software Foundation</A> |
| 215 | or email <code>ijackson@chiark.greenend.org.uk</code>. |
| 216 | |
| 217 | <p> |
| 218 | |
| 219 | <hr> |
| 220 | Ian Jackson / <tt>ijackson@chiark.greenend.org.uk</tt>. |
| 221 | <p> |
| 222 | |
| 223 | <A href="http://www.gnu.org/">GNU home page</A>; |
| 224 | <A href="http://www.chiark.greenend.org.uk/">chiark home page</A>; |
| 225 | <A href="/">site or mirror home page</A> |
| 226 | <p> |
| 227 | |
| 228 | This web page is Copyright (C)1996-2005,2014 Ian Jackson. See the |
| 229 | <A href="http://www.chiark.greenend.org.uk/~ian/sw-www-copy.html">Copyright/acknowledgements</A>. |
| 230 | |
| 231 | </body> |
| 232 | </html> |