worley@compass.com (Dale Worley) (09/16/90)
This is to thank all the people who sent me information about rstatd and about using UDP connections in Perl: Larry Wall Carl Smith Vipin Samar Guy Harris Michael van Elst (and any I've forgotten!) My original idea was to have a program query all the hosts on our network to determine which were idle (according to some criterion). I want to know: load average, amount of virtual memory free, and keyboard idle time. Load average is available from rstatd, keyboard idle time is (probably) available from rusersd, and it seems that free virtual memory (printed by pstat -s) is probably not available from any daemon, unless I write my own. (While we're at it, is there any way to get the genuine keyboard idle time when SunTools is running? 'w' shows the console as being idle for a very long time, while input generated by a shelltool into its pty stimulated by '^[[11t' are recorded as if it is genuine input.) To interact with a UDP daemon in Perl, you need to open the connection with the UDP protocol, rather than TCP. Each print sends a UDP packet, and each read gets a UDP packet. You can also use send or recv without connecting the socket. RPC and XDR are described in Network Programming, chapters 5 and 6 (set I, vol. XI in the 4.0.3 documentation). Using the RPC protocol is much simpler than it appears from the manual: XDR is just a machine independent way to represent data structures. The basic rule is that integers are represented as four-byte network order integers (format N for pack and unpack). Also, don't forget that port 111 (a/k/a sunrpc) only handles portmapper requests -- you either have to ask the portmapper for the port of the service you want, or you have to ask the portmapper to forward the request for you (the approach taken by the code below). #!/usr/local/bin/perl ($host) = @ARGV; die "usage: $0 hostname\n" unless $host; $pat = 'S n C4 x8'; $stream = 1; $datagram = 2; $inet = 2; $tcp = 6; $udp = 17; ($name,$aliases,$port) = getservbyname('sunrpc','udp'); if ($host =~ /^\d+\./) { @bytes = split(/\./,$host); } else { ($name,$aliases,$addrtype,$length,@addrs) = gethostbyname($host); die "Can't lookup $host\n" unless $name; @bytes = unpack("C4",$addrs[0]); } $this = pack($pat,$inet,0, 0,0,0,0); $that = pack($pat,$inet,$port,@bytes); socket(S,2,$datagram,$udp) || die "socket: $!\n"; bind(S,$this) || die "bind: $!\n"; connect(S,$that) || die "connect: $!\n"; select(S); $| = 1; select(stdout); $| = 1; #while (1) { print S pack("N13", 1956, 0, 2, 100000, 2, 5, 0, 0, 0, 0, 100001, 3, 1); read(S, $_, 32767); @r = unpack("N" . length($_)/4, $_); #print join(' ', @r), "\n"; print $r[26]/256, ' ', $r[27]/256, ' ', $r[28]/256, "\n"; if ($r[0] != 1956) { die "xid error\n"; } elsif ($r[1] != 1) { die "Not a reply!\n"; } elsif ($r[2] == 1) { if ($r[3] == 0) { die "Rejected - RPC_MISMATCH\n"; } elsif ($r[3] == 1) { die "Rejected - AUTH_ERROR\n"; } else { die "Rejected - unknown code\n"; } } else { print '', (("SUCCESS", "PROG_UNAVAIL", "PROG_MISMATCH", "PROC_UNAVAIL", "GARBAGE_ARGS")[$r[5]]), "\n"; } Dale Worley Compass, Inc. worley@compass.com Oh, yeah -- the calling and returning data structures for the RPC daemons and the various code numbers are in the files /usr/include/rpcsvc/*.x.