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package network // import "collectd.org/network"
import (
"log"
"net"
"collectd.org/api"
)
// ListenAndWrite listens on the provided UDP address, parses the received
// packets and writes them to the provided api.Writer.
// This is a convenience function for a minimally configured server. If you
// need more control, see the "Server" type below.
func ListenAndWrite(address string, d api.Writer) error {
srv := &Server{
Addr: address,
Writer: d,
}
return srv.ListenAndWrite()
}
// Server holds parameters for running a collectd server.
type Server struct {
Addr string // UDP address to listen on.
Writer api.Writer // Object used to send incoming ValueLists to.
BufferSize uint16 // Maximum packet size to accept.
PasswordLookup PasswordLookup // User to password lookup.
SecurityLevel SecurityLevel // Minimal required security level
// Interface is the name of the interface to use when subscribing to a
// multicast group. Has no effect when using unicast.
Interface string
}
// ListenAndWrite listens on the provided UDP address, parses the received
// packets and writes them to the provided api.Writer.
func (srv *Server) ListenAndWrite() error {
addr := srv.Addr
if addr == "" {
addr = ":" + DefaultService
}
laddr, err := net.ResolveUDPAddr("udp", srv.Addr)
if err != nil {
return err
}
var sock *net.UDPConn
if laddr.IP.IsMulticast() {
var ifi *net.Interface
if srv.Interface != "" {
if ifi, err = net.InterfaceByName(srv.Interface); err != nil {
return err
}
}
sock, err = net.ListenMulticastUDP("udp", ifi, laddr)
} else {
sock, err = net.ListenUDP("udp", laddr)
}
if err != nil {
return err
}
defer sock.Close()
if srv.BufferSize <= 0 {
srv.BufferSize = DefaultBufferSize
}
buf := make([]byte, srv.BufferSize)
popts := ParseOpts{
PasswordLookup: srv.PasswordLookup,
SecurityLevel: srv.SecurityLevel,
}
for {
n, err := sock.Read(buf)
if err != nil {
return err
}
valueLists, err := Parse(buf[:n], popts)
if err != nil {
log.Printf("error while parsing: %v", err)
continue
}
go dispatch(valueLists, srv.Writer)
}
}
func dispatch(valueLists []api.ValueList, d api.Writer) {
for _, vl := range valueLists {
if err := d.Write(vl); err != nil {
log.Printf("error while dispatching: %v", err)
}
}
}
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