c-ares
======

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, and in a
git repository: http://github.com/bagder/c-ares

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: http://cool.haxx.se/mailman/listinfo/c-ares

c-ares is of course distributed under the same MIT-style license as the
original ares.

You'll find all c-ares details and news here:

        http://c-ares.haxx.se/


NOTES FOR C-ARES HACKERS

The following notes apply to c-ares version 1.7.0 and later.

* 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 of compiling 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 */

c-ares
======

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

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

The original libares was distributed at athena-dist.mit.edu:pub/ATHENA/ares.

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                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', 'acountry', 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.


  How to build using Visual Studio 6 IDE
  --------------------------------------

  A VC++ 6.0 reference workspace (vc6aws.dsw) is available within the 'vc'
  folder to allow proper building of the library and sample programs.

  1) Open the vc6aws.dsw workspace with MSVC6's IDE.
  2) Select 'Build' from top menu.
  3) Select 'Batch Build' from dropdown menu.
  4) Make sure that the sixteen project configurations are 'checked'.
  5) Click on the 'Build' button.
  6) Once the sixteen project configurations are built you are done.

  Dynamic and static c-ares libraries are built in debug and release flavours,
  and can be located each one in its own subdirectory, dll-debug, dll-release,
  lib-debug and lib-release, all of them below the 'vc\cares' subdirectory.

  In the same way four executable versions of each sample program are built,
  each using its respective library. The resulting sample executables are
  located in its own subdirectory, dll-debug, dll-release, lib-debug and
  lib-release, below the 'vc\acountry', 'vc\adig' and 'vc\ahost'folders.

  These reference VC++ 6.0 configurations are generated using the dynamic CRT.


  How to build using Visual Studio 2003 or newer IDE
  --------------------------------------------------

  First you have to convert the VC++ 6.0 reference workspace and project files
  to the Visual Studio IDE version you are using, following next steps:

  1) Open vc\vc6aws.dsw with VS20XX.
  2) Allow VS20XX to update all projects and workspaces.
  3) Save ALL and close VS20XX.
  4) Open vc\vc6aws.sln with VS20XX.
  5) Select batch build, check 'all' projects and click 'build' button.

  Same comments relative to generated files and folders as done above for
  Visual Studio 6 IDE apply here.


  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!