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42 lines
2.1 KiB
42 lines
2.1 KiB
21 years ago
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This is ares, an asynchronous resolver library. It is intended for
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applications which need to perform DNS queries without blocking, or
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need to perform multiple DNS queries in parallel. The primary
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examples of such applications are servers which communicate with
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multiple clients and programs with graphical user interfaces.
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This library implementation is not especially portable to crufty old
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systems like SunOS 4. It assumes a compiler which can handle ANSI C
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syntax, a system malloc which properly handles realloc(NULL, foo) and
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free(NULL), and a reasonably up-to-date <arpa/nameser.h>.
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I have attempted to preserve the externally visible behavior of the
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BIND resolver in nearly all respects. The API of the library is, of
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course, very different from the synchronous BIND API; instead of
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invoking a function like res_send() and getting a return value back
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indicating the number of bytes in the response, you invoke a function
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like ares_send() and give it a callback function to invoke when the
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response arrives. You then have to select() on the file descriptors
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indicated by ares_fds(), with a timeout given by ares_timeout(). You
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call ares_process() when select() returns.
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Some features are missing from the current version of ares, relative
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to the BIND resolver:
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* There is no IPV6 support.
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* There is no hostname verification.
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* There is no logging of unexpected events.
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* There is no debugging-oriented logging.
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* There is no YP support.
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libares requires an ANSI compiler to compile and use. To build the
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library, just run "./configure" and "make". To install it, run "make
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install". Run "./configure --help" to see a list of options you can
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provide to configure to change how the library builds. libares has no
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data files, so you can move the include file and library around freely
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without leaving behind any dependencies on old paths. Building the
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library will also build the "adig" program, a little toy for trying
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out the library. It doesn't get installed.
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libares is distributed at athena-dist.mit.edu:pub/ATHENA/ares. Please
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send bug reports and comments to ghudson@mit.edu.
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