mdw@git.distorted.org.uk Git - adns/blob - README

   1
   2                                    GNU adns
   3
   4    Advanced, easy to use, asynchronous-capable DNS client library and
   5    utilities.
   6
   7    adns is a resolver library for C (and C++) programs, and a collection
   8    of useful DNS resolver utilities.
   9
  10 C library
  11
  12    In contrast with the standard interfaces, gethostbyname et al and
  13    libresolv, it has the following features:
  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
  25        an easy-to-use form, without getting in the way.
  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
  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.
  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.
  41
  42 DNS utility programs
  43
  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
  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
  55        can invoke and communicate with subprocesses. See the [1]adnshost
  56        usage message for a summary of its capabilities.
  57
  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
  70 Documentation
  71
  72    I'm afraid there is no manual yet. However, competent C programmers
  73    should be able to use the library based on the [2]commented adns.h
  74    header file, and the usage messages for the programs should be
  75    sufficient.
  76
  77 Feedback
  78
  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.
  81
  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
  86    adns-maint@chiark.greenend.org.uk.
  87
  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
  92    important bugs, new versions, etc. The bug reports address mentioned
  93    above is also a mailing list; feel free to subscribe to it.
  94
  95    There are [3]archives and subscription web pages, or you can subscribe
  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.
  99
 100 Download
 101
 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
 105        adnshost (currently there is no manual, sorry).
 106      * All versions released so far are also available via [8]anonymous
 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
 111        rsync.chiark.greenend.org.uk::ftp/users/ian/cvs-pub/adns (use FTP
 112        first to find your way around), or via [10]cvsweb.
 113      * This web page is maintained in [11]Savannah, where you can browse
 114        the [12]webpage CVS.
 115
 116    adns is also available from the [13]GNU Project FTP servers and their
 117    [14]mirrors.
 118
 119 Technical note
 120
 121    adns requires a real nameserver like [15]BIND or [16]Dents running on
 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.
 126
 127 References and related projects
 128
 129      * [17]Python bindings by Andy Dustman.
 130      * [18]Haskell bindings by Peter Simons.
 131      * [19]liboop event loop library (by Dan Egnor) has a built-in
 132        binding for adns.
 133      * [20]port to MS Visual Studio 6 C++ by Jarle Aase.
 134
 135 Copyright and licensing
 136
 137    adns is Copyright 1997-2005 Ian Jackson, Copyright 1999-2004 Tony
 138    Finch, and Copyright (C) 1991 Massachusetts Institute of Technology.
 139
 140    adns is free software; you can redistribute it and/or modify it under
 141    the terms of the GNU General Public License as published by the Free
 142    Software Foundation; either version 2 of the License, or (at your
 143    option) any later version.
 144
 145    This program and documentation is distributed in the hope that it will
 146    be useful, but without any warranty; without even the implied warranty
 147    of merchantability or fitness for a particular purpose. See the
 148    [21]GNU General Public License for more details.
 149
 150    You should have received a copy of the GNU General Public License
 151    along with adns, or one should be available above; if not, write to
 152    the [22]Free Software Foundation, 59 Temple Place - Suite 330, Boston,
 153    MA 02111-1307, USA, or email adns-maint@chiark.greenend.org.uk.
 154      _________________________________________________________________
 155
 156    [23]Ian Jackson / [24]adns-maint@chiark.greenend.org.uk; more [25]free
 157    software by me.
 158
 159    [26]GNU home page; [27]chiark home page; [28]site or mirror home page
 160
 161    This web page is Copyright (C)1996-2005 Ian Jackson. See the
 162    [29]Copyright/acknowledgements.
 163
 164    Use any browser - [30]Campaign for a non-browser-specific WWW
 165
 166 References
 167
 168    1. http://www.chiark.greenend.org.uk/~ian/adns/adnshost.txt
 169    2. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.txt
 170    3. http://www.chiark.greenend.org.uk/mailman/listinfo
 171    4. http://www.chiark.greenend.org.uk/~ian/adns/
 172    5. http://www.chiark.greenend.org.uk/~ian/adns/adns.tar.gz
 173    6. http://www.chiark.greenend.org.uk/~ian/adns/adns.h.txt
 174    7. http://www.chiark.greenend.org.uk/~ian/adns/adnshost.txt
 175    8. ftp://ftp.chiark.greenend.org.uk/users/ian/adns/
 176    9. http://www.chiark.greenend.org.uk/~ian/adns/ftp/
 177   10. http://www.chiark.greenend.org.uk/ucgi/~ijackson/cvsweb/adns/
 178   11. http://savannah.gnu.org/
 179   12. http://savannah.gnu.org/cgi-bin/viewcvs/software/adns/?cvsroot=www.gnu.org
 180   13. http://www.gnu.org/
 181   14. http://www.gnu.org/order/ftp.html
 182   15. http://www.isc.org/view.cgi?/products/BIND/index.phtml
 183   16. http://www.dents.org/
 184   17. http://dustman.net/andy/python/adns-python
 185   18. http://cryp.to/hsdns/
 186   19. http://liboop.ofb.net/ref
 187   20. http://adns.jgaa.com/
 188   21. http://www.chiark.greenend.org.uk/~ian/COPYING.txt
 189   22. http://www.fsf.org/
 190   23. http://www.chiark.greenend.org.uk/
 191   24. mailto:adns-maint@chiark.greenend.org.uk
 192   25. http://www.chiark.greenend.org.uk/~ian/software/
 193   26. http://www.gnu.org/
 194   27. http://www.chiark.greenend.org.uk/
 195   28. file://localhost/
 196   29. http://www.chiark.greenend.org.uk/~ian/sw-www-copy.html
 197   30. http://www.anybrowser.org/campaign/