Warren Young <warren@etr-usa.com>
AllPermissive 
Copying and distribution of this file, with or
        without modification, are permitted in any medium without royalty provided the copyright
        notice and this notice are preserved. Users of this software should generally follow the
        principles of the 
        MIT License includings its disclaimer. 
cryp.to ac-archive's Obsoleted (obsoleted)
This macro figures out what libraries are required on this platform
to link sockets programs. It's usually -lsocket and/or -lnsl or
neither. We test for all three combinations.
AC_DEFUN([ETR_SOCKET_NSL],
[
AC_CACHE_CHECK(for libraries containing socket functions,
ac_cv_socket_libs, [
        oCFLAGS=$CFLAGS
        AC_TRY_LINK([
                        #include <sys/types.h>
                        #include <sys/socket.h>
                        #include <netinet/in.h>
                        #include <arpa/inet.h>
                ],
                [
                        struct in_addr add;
                        int sd = socket(AF_INET, SOCK_STREAM, 0);
                        inet_ntoa(add);
                ],
                ac_cv_socket_libs=-lc, ac_cv_socket_libs=no)
        if test x"$ac_cv_socket_libs" = "xno"
        then
                CFLAGS="$oCFLAGS -lsocket"
                AC_TRY_LINK([
                                #include <sys/types.h>
                                #include <sys/socket.h>
                                #include <netinet/in.h>
                                #include <arpa/inet.h>
                        ],
                        [
                                struct in_addr add;
                                int sd = socket(AF_INET, SOCK_STREAM, 0);
                                inet_ntoa(add);
                        ],
                        ac_cv_socket_libs=-lsocket, ac_cv_socket_libs=no)
        fi
        if test x"$ac_cv_socket_libs" = "xno"
        then
                CFLAGS="$oCFLAGS -lsocket -lnsl"
                AC_TRY_LINK([
                                #include <sys/types.h>
                                #include <sys/socket.h>
                                #include <netinet/in.h>
                                #include <arpa/inet.h>
                        ],
                        [
                                struct in_addr add;
                                int sd = socket(AF_INET, SOCK_STREAM, 0);
                                inet_ntoa(add);
                        ],
                        ac_cv_socket_libs="-lsocket -lnsl", ac_cv_socket_libs=no)
        fi
        CFLAGS=$oCFLAGS
])
        if test x"$ac_cv_socket_libs" = "xno"
        then
                AC_MSG_ERROR([Cannot find socket libraries])
        elif test x"$ac_cv_socket_libs" = "x-lc"
        then
                ETR_SOCKET_LIBS=""
        else
                ETR_SOCKET_LIBS="$ac_cv_socket_libs"
        fi
        AC_SUBST(ETR_SOCKET_LIBS)
]) dnl ETR_SOCKET_NSL