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