c-ares
======

This package is based on ares 1.1.1 (written by Greg Hudson). Daniel Stenberg
decided to fork and release a separate project since the original ares author
didn't want the improvements that were vital for our use of it.

This package is dubbed 'c-ares' since Daniel wanted this for use within the
curl project (hence the letter C) and it makes a nice pun. c-ares is not API
compatible with ares: a new name makes that more obvious to the public.

The original libares was distributed at
ftp://athena-dist.mit.edu:pub/ATHENA/ares (which seems to not be alive
anymore).  A local copy of the original ares package is kept here:
https://c-ares.org/download/ares-1.1.1.tar.gz

# [![c-ares logo](https://c-ares.org/art/c-ares-logo.svg)](https://c-ares.org/)

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This is c-ares, an asynchronous resolver library.  It is intended for
applications which need to perform DNS queries without blocking, or need to
perform multiple DNS queries in parallel.  The primary examples of such
applications are servers which communicate with multiple clients and programs
with graphical user interfaces.

The full source code is available in the ['c-ares' release archives](https://c-ares.org/download/),
and in a git repository: https://github.com/c-ares/c-ares.  See the
[INSTALL.md](INSTALL.md) file for build information.

If you find bugs, correct flaws, have questions or have comments in general in
regard to c-ares (or by all means the original ares too), get in touch with us
on the c-ares mailing list: https://lists.haxx.se/listinfo/c-ares

c-ares is distributed under the MIT license.

You'll find all c-ares details and news here:
        https://c-ares.org/


## Notes for c-ares hackers

* The distributed `ares_build.h` file is only intended to be used on systems
  which can not run the also distributed configure script.

* The distributed `ares_build.h` file is generated as a copy of `ares_build.h.dist`
  when the c-ares source code distribution archive file is originally created.

* If you check out from git on a non-configure platform, you must run the
  appropriate `buildconf*` script to set up `ares_build.h` and other local files
  before being able to compile the library.

* On systems capable of running the `configure` script, the `configure` process
  will overwrite the distributed `ares_build.h` file with one that is suitable
  and specific to the library being configured and built, this new file is
  generated from the `ares_build.h.in` template file.

* If you intend to distribute an already compiled c-ares library you **MUST**
  also distribute along with it the generated `ares_build.h` which has been
  used to compile it. Otherwise, the library will be of no use for the users of
  the library that you have built. It is **your** responsibility to provide this
  file. No one at the c-ares project can know how you have built the library.

* File `ares_build.h` includes platform and configuration dependent info,
  and must not be modified by anyone. Configure script generates it for you.

* We cannot assume anything else but very basic compiler features being
  present. While c-ares requires an ANSI C compiler to build, some of the
  earlier ANSI compilers clearly can't deal with some preprocessor operators.

* Newlines must remain unix-style for older compilers' sake.

* Comments must be written in the old-style /* unnested C-fashion */

* Try to keep line lengths below 80 columns.

                          ___       __ _ _ __ ___  ___
                         / __| ___ / _` | '__/ _ \/ __|
                        | (_  |___| (_| | | |  __/\__ \
                         \___|     \__,_|_|  \___||___/


                How to build c-ares using MSVC or Visual Studio
               =================================================



  How to build using MSVC from the command line
  ---------------------------------------------

  Open a command prompt window and ensure that the environment is properly
  set up in order to use MSVC or Visual Studio compiler tools.

  Change to c-ares source folder where Makefile.msvc file is located and run:

  > nmake -f Makefile.msvc

  This will build all c-ares libraries as well as three sample programs.

  Once the above command has finished a new folder named MSVCXX will exist
  below the folder where makefile.msvc is found. The name of the folder
  depends on the MSVC compiler version being used to build c-ares.

  Below the MSVCXX folder there will exist four folders named 'cares',
  'ahost', and 'adig'. The 'cares' folder is the one that
  holds the c-ares libraries you have just generated, the other three
  hold sample programs that use the libraries.

  The above command builds four versions of the c-ares library, dynamic
  and static versions and each one in release and debug flavours. Each
  of these is found in folders named dll-release, dll-debug, lib-release,
  and lib-debug, which hang from the 'cares' folder mentioned above. Each
  sample program also has folders with the same names to reflect which
  library version it is using.


  How to install using MSVC from the command line
  -----------------------------------------------

  In order to allow easy usage of c-ares libraries it may be convenient to
  install c-ares libraries and header files to a common subdirectory tree.

  Once that c-ares libraries have been built using procedure described above,
  use same command prompt window to define environment variable INSTALL_DIR
  to designate the top subdirectory where installation of c-ares libraries and
  header files will be done.

  > set INSTALL_DIR=c:\c-ares

  Afterwards, run following command to actually perform the installation:

  > nmake -f Makefile.msvc install

  Installation procedure will copy c-ares libraries to subdirectory 'lib' and
  c-ares header files to subdirectory 'include' below the INSTALL_DIR subdir.

  When environment variable INSTALL_DIR is not defined, installation is done
  to c-ares source folder where Makefile.msvc file is located.



  Relationship between c-ares library file names and versions
  -----------------------------------------------------------

  c-ares static release library version files:

      libcares.lib -> static release library

  c-ares static debug library version files:

      libcaresd.lib -> static debug library

  c-ares dynamic release library version files:

      cares.dll -> dynamic release library
      cares.lib -> import library for the dynamic release library
      cares.exp -> export file for the dynamic release library

  c-ares dynamic debug library version files:

      caresd.dll -> dynamic debug library
      caresd.lib -> import library for the dynamic debug library
      caresd.exp -> export file for the dynamic debug library
      caresd.pdb -> debug symbol file for the dynamic debug library


  How to use c-ares static libraries
  ----------------------------------

  When using the c-ares static library in your program, you will have to
  define preprocessor symbol CARES_STATICLIB while building your program,
  otherwise you will get errors at linkage stage.


Have Fun!