The gai_strerror() function shall return a text string describing an
error value for the getaddrinfo() and getnameinfo() functions
listed in the <netdb.h> header.
When the ecode argument is one of the following values listed in the
the function return value shall point to a string describing the error. If the
argument is not one of those values, the function shall return a pointer to a
string whose contents indicate an unknown error.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html