Re: Asynchronous DNS name resolution / DNS timeouts


root wrote:
Sometimes I find that when DNS name resolution is not immediately
successful, gethostbyname() may block for unacceptable time, causing my
client program to become unresponsive. My question is, how should I
implement either DNS timeouts, or totally asynchronous DNS name
resolution? Do I need to write a proper DNS client from scratch from the
RFC? This is worse on some platforms than others.
Also gethostbyname() is poor because it is returning a pointer to static
data structure, and I currently must use mutexes to protect this call in
the multithreaded code. My code must be portable across HP/UX, Irix,
AIX, Linux, Solaris, Tru64, and Windows, so I have minimal choice about
what functions to use (gethostbyname_r() not supported on everything)

Try calling alarm() before the call to gethostbyname(), so that it is
interrupted when the alarm timeout reaches and SIGALRM is sent to your
application.

.

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