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* dhcp: refactor; log client's HW addr

This commit is contained in:
Simon Zolin 2019-02-28 18:24:01 +03:00
parent 10daf29e2f
commit 60fa3b2e95
1 changed files with 37 additions and 28 deletions
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65
dhcpd/dhcpd.go
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@ -126,6 +126,7 @@ func (s *Server) Start(config *ServerConfig) error {
if err != nil { if err != nil {
return wrapErrPrint(err, "Couldn't start listening socket on 0.0.0.0:67") return wrapErrPrint(err, "Couldn't start listening socket on 0.0.0.0:67")
} }
log.Info("DHCP: listening on 0.0.0.0:67")
s.conn = c s.conn = c
@ -213,7 +214,7 @@ func (s *Server) findFreeIP(hwaddr net.HardwareAddr) (net.IP, error) {
var foundIP net.IP var foundIP net.IP
for i := 0; i < dhcp4.IPRange(s.leaseStart, s.leaseStop); i++ { for i := 0; i < dhcp4.IPRange(s.leaseStart, s.leaseStop); i++ {
newIP := dhcp4.IPAdd(s.leaseStart, i) newIP := dhcp4.IPAdd(s.leaseStart, i)
foundHWaddr := s.getIPpool(newIP) foundHWaddr := s.findReservedHWaddr(newIP)
log.Tracef("tried IP %v, got hwaddr %v", newIP, foundHWaddr) log.Tracef("tried IP %v, got hwaddr %v", newIP, foundHWaddr)
if foundHWaddr != nil && len(foundHWaddr) != 0 { if foundHWaddr != nil && len(foundHWaddr) != 0 {
// if !bytes.Equal(foundHWaddr, hwaddr) { // if !bytes.Equal(foundHWaddr, hwaddr) {
@ -236,7 +237,7 @@ func (s *Server) findFreeIP(hwaddr net.HardwareAddr) (net.IP, error) {
return foundIP, nil return foundIP, nil
} }
func (s *Server) getIPpool(ip net.IP) net.HardwareAddr { func (s *Server) findReservedHWaddr(ip net.IP) net.HardwareAddr {
rawIP := []byte(ip) rawIP := []byte(ip)
IP4 := [4]byte{rawIP[0], rawIP[1], rawIP[2], rawIP[3]} IP4 := [4]byte{rawIP[0], rawIP[1], rawIP[2], rawIP[3]}
return s.IPpool[IP4] return s.IPpool[IP4]
@ -256,33 +257,22 @@ func (s *Server) unreserveIP(ip net.IP) {
// ServeDHCP handles an incoming DHCP request // ServeDHCP handles an incoming DHCP request
func (s *Server) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dhcp4.Options) dhcp4.Packet { func (s *Server) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dhcp4.Options) dhcp4.Packet {
log.Tracef("Got %v message", msgType) log.Tracef("Message from client %s: %d", p.CHAddr(), msgType)
log.Tracef("Leases:") log.Tracef("Leases:")
for i, lease := range s.leases { for i, lease := range s.leases {
log.Tracef("Lease #%d: hwaddr %s, ip %s, expiry %s", i, lease.HWAddr, lease.IP, lease.Expiry) log.Tracef("Lease #%d: hwaddr %s, ip %s, expiry %s", i, lease.HWAddr, lease.IP, lease.Expiry)
} }
log.Tracef("IP pool:")
for ip, hwaddr := range s.IPpool {
log.Tracef("IP pool entry %s -> %s", net.IPv4(ip[0], ip[1], ip[2], ip[3]), hwaddr)
}
switch msgType { switch msgType {
case dhcp4.Discover: // Broadcast Packet From Client - Can I have an IP? case dhcp4.Discover: // Broadcast Packet From Client - Can I have an IP?
// find a lease, but don't update lease time return s.handleDiscover(p, options)
log.Tracef("Got from client: Discover")
lease, err := s.reserveLease(p)
if err != nil {
log.Tracef("Couldn't find free lease: %s", err)
// couldn't find lease, don't respond
return nil
}
reply := dhcp4.ReplyPacket(p, dhcp4.Offer, s.ipnet.IP, lease.IP, s.leaseTime, s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList]))
log.Tracef("Replying with offer: offered IP %v for %v with options %+v", lease.IP, s.leaseTime, reply.ParseOptions())
return reply
case dhcp4.Request: // Broadcast From Client - I'll take that IP (Also start for renewals) case dhcp4.Request: // Broadcast From Client - I'll take that IP (Also start for renewals)
// start/renew a lease -- update lease time // start/renew a lease -- update lease time
// some clients (OSX) just go right ahead and do Request first from previously known IP, if they get NAK, they restart full cycle with Discover then Request // some clients (OSX) just go right ahead and do Request first from previously known IP, if they get NAK, they restart full cycle with Discover then Request
return s.handleDHCP4Request(p, options) return s.handleDHCP4Request(p, options)
case dhcp4.Decline: // Broadcast From Client - Sorry I can't use that IP case dhcp4.Decline: // Broadcast From Client - Sorry I can't use that IP
log.Tracef("Got from client: Decline") log.Tracef("Got from client: Decline")
@ -291,25 +281,43 @@ func (s *Server) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dh
case dhcp4.Inform: // From Client, I have this IP and there's nothing you can do about it case dhcp4.Inform: // From Client, I have this IP and there's nothing you can do about it
log.Tracef("Got from client: Inform") log.Tracef("Got from client: Inform")
// do nothing
// from server -- ignore those but enumerate just in case // from server -- ignore those but enumerate just in case
case dhcp4.Offer: // Broadcast From Server - Here's an IP case dhcp4.Offer: // Broadcast From Server - Here's an IP
log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: Offer") log.Printf("DHCP: received message from another server: Offer")
case dhcp4.ACK: // From Server, Yes you can have that IP case dhcp4.ACK: // From Server, Yes you can have that IP
log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: ACK") log.Printf("DHCP: received message from another server: ACK")
case dhcp4.NAK: // From Server, No you cannot have that IP case dhcp4.NAK: // From Server, No you cannot have that IP
log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: NAK") log.Printf("DHCP: received message from another server: NAK")
default: default:
log.Printf("Unknown DHCP packet detected, ignoring: %v", msgType) log.Printf("DHCP: unknown packet %v from client %s", msgType, p.CHAddr())
return nil return nil
} }
return nil return nil
} }
func (s *Server) handleDiscover(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet {
// find a lease, but don't update lease time
lease, err := s.reserveLease(p)
if err != nil {
log.Tracef("Couldn't find free lease: %s", err)
// couldn't find lease, don't respond
return nil
}
opt := s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList])
reply := dhcp4.ReplyPacket(p, dhcp4.Offer, s.ipnet.IP, lease.IP, s.leaseTime, opt)
log.Tracef("Replying with offer: offered IP %v for %v with options %+v", lease.IP, s.leaseTime, reply.ParseOptions())
return reply
}
func (s *Server) handleDHCP4Request(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet { func (s *Server) handleDHCP4Request(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet {
log.Tracef("Got from client: Request") server := options[dhcp4.OptionServerIdentifier]
if server, ok := options[dhcp4.OptionServerIdentifier]; ok && !net.IP(server).Equal(s.ipnet.IP) { if server != nil && !net.IP(server).Equal(s.ipnet.IP) {
log.Tracef("Request message not for this DHCP server (%v vs %v)", server, s.ipnet.IP) log.Tracef("Request message not for this DHCP server (%v vs %v)", server, s.ipnet.IP)
return nil // Message not for this dhcp server return nil // Message not for this dhcp server
} }
@ -341,7 +349,8 @@ func (s *Server) handleDHCP4Request(p dhcp4.Packet, options dhcp4.Options) dhcp4
// IP matches lease IP, nothing else to do // IP matches lease IP, nothing else to do
lease.Expiry = time.Now().Add(s.leaseTime) lease.Expiry = time.Now().Add(s.leaseTime)
log.Tracef("Replying with ACK: request IP matches lease IP, nothing else to do. IP %v for %v", lease.IP, p.CHAddr()) log.Tracef("Replying with ACK: request IP matches lease IP, nothing else to do. IP %v for %v", lease.IP, p.CHAddr())
return dhcp4.ReplyPacket(p, dhcp4.ACK, s.ipnet.IP, lease.IP, s.leaseTime, s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList])) opt := s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList])
return dhcp4.ReplyPacket(p, dhcp4.ACK, s.ipnet.IP, lease.IP, s.leaseTime, opt)
} }
// //
@ -350,7 +359,7 @@ func (s *Server) handleDHCP4Request(p dhcp4.Packet, options dhcp4.Options) dhcp4
log.Tracef("lease IP is different from requested IP: %s vs %s", lease.IP, reqIP) log.Tracef("lease IP is different from requested IP: %s vs %s", lease.IP, reqIP)
hwaddr := s.getIPpool(reqIP) hwaddr := s.findReservedHWaddr(reqIP)
if hwaddr == nil { if hwaddr == nil {
// not in pool, check if it's in DHCP range // not in pool, check if it's in DHCP range
if dhcp4.IPInRange(s.leaseStart, s.leaseStop, reqIP) { if dhcp4.IPInRange(s.leaseStart, s.leaseStop, reqIP) {
@ -379,7 +388,7 @@ func (s *Server) handleDHCP4Request(p dhcp4.Packet, options dhcp4.Options) dhcp4
return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil) return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
} }
// Leases returns the list of current DHCP leases // Leases returns the list of current DHCP leases (thread-safe)
func (s *Server) Leases() []*Lease { func (s *Server) Leases() []*Lease {
s.RLock() s.RLock()
result := s.leases result := s.leases