func setEntry(buf []byte, entry int, family int, tag uint16, netaddr net.IPNet, nexthop net.IP, metric int) {
offset := ripEntryOffset(entry)
netorder.WriteUint16(buf, offset, uint16(family))
netorder.WriteUint16(buf, offset+2, tag)
addr.WriteIPv4(buf, offset+4, netaddr.IP)
addr.WriteIPv4Mask(buf, offset+8, netaddr.Mask)
addr.WriteIPv4(buf, offset+12, nexthop)
netorder.WriteUint32(buf, offset+16, uint32(metric))
}
func query(hostPort string, nets []string) {
entries := len(nets)
bufSize := 4 + 20*entries
buf := make([]byte, bufSize, bufSize)
buf[0] = 1 // rip request
buf[1] = 2 // rip version
for i, n := range nets {
family := uint16(2) // AF_INET
f := strings.Split(n, ",")
if len(f) > 1 {
af, err := strconv.Atoi(f[1])
if err == nil {
family = uint16(af)
n = f[0]
} else {
fmt.Printf("could not solve address family: '%s': %v\n", n, err)
return
}
}
_, netaddr, err := net.ParseCIDR(n)
if err != nil {
fmt.Printf("could not solve network: '%s': %v\n", n, err)
return
}
offset := 4 + 20*i
netorder.WriteUint16(buf, offset, family)
netorder.WriteUint16(buf, offset+2, 0) // route tag
addr.WriteIPv4(buf, offset+4, netaddr.IP)
addr.WriteIPv4Mask(buf, offset+8, netaddr.Mask)
addr.WriteIPv4(buf, offset+12, net.IPv4(0, 0, 0, 0))
netorder.WriteUint32(buf, offset+16, 16) // metric
}
proto := "udp"
raddr, err := net.ResolveUDPAddr(proto, hostPort)
if err != nil {
fmt.Printf("could not solve udp endpoint: '%s': %v\n", hostPort, err)
return
}
conn, err := net.DialUDP(proto, nil, raddr)
if err != nil {
fmt.Printf("could not create connection for remote endpoint: %v: %v\n", raddr, err)
return
}
n, err := conn.Write(buf)
if err != nil {
fmt.Printf("could not send rip dgram: size=%d to %v: %v\n", len(buf), raddr, err)
return
}
if n != len(buf) {
fmt.Printf("partil write rip dgram: sent=%d size=%d to %v: %v\n", n, len(buf), raddr, err)
return
}
fmt.Printf("sent rip dgram: size=%d to %v\n", len(buf), raddr)
}