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dhcpd: imp code
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@EugeneOne1
EugeneOne1 committed Aug 30, 2022
1 parent 9fe3019 commit fafbc2e
Showing 1 changed file with 60 additions and 55 deletions.
115 changes: 60 additions & 55 deletions internal/dhcpd/v4.go
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Original file line number Diff line number Diff line change
Expand Up @@ -542,24 +542,18 @@ func (s *v4Server) reserveLease(mac net.HardwareAddr) (l *Lease, err error) {
return l, nil
}

// commitLease refreshes the l's values. A non-empty prevName will be removed
// from the known hostnames registry.
// commitLease refreshes l's values. A non-empty prevName will be removed from
// the known hostnames registry.
func (s *v4Server) commitLease(l *Lease, prevName string) {
l.Expiry = time.Now().Add(s.conf.leaseTime)

func() {
s.leasesLock.Lock()
defer s.leasesLock.Unlock()

s.conf.notify(LeaseChangedDBStore)
s.conf.notify(LeaseChangedDBStore)

if prevName != "" && prevName != l.Hostname {
s.leaseHosts.Del(prevName)
}
if l.Hostname != "" {
s.leaseHosts.Add(l.Hostname)
}
}()
l.Expiry = time.Now().Add(s.conf.leaseTime)
if prevName != "" && prevName != l.Hostname {
s.leaseHosts.Del(prevName)
}
if l.Hostname != "" {
s.leaseHosts.Add(l.Hostname)
}

s.conf.notify(LeaseChangedAdded)
}
Expand Down Expand Up @@ -669,11 +663,8 @@ func (s *v4Server) checkLease(mac net.HardwareAddr, ip net.IP) (lease *Lease, mi
// setHostname sets the unique hostname, either requested or generated, to the
// lease and to the DHCP response if the one is requested. It returns the
// previous value of the lease's hostname.
func (s *v4Server) setHostname(req, resp *dhcpv4.DHCPv4, lease *Lease) (prev string) {
func (s *v4Server) setHostname(lease *Lease, hostname string) (prev string) {
prev = lease.Hostname

hostname := req.HostName()
requested := hostname != "" || req.ParameterRequestList().Has(dhcpv4.OptionHostName)
hostname = s.validHostnameForClient(hostname, lease.IP)

if s.leaseHosts.Has(hostname) {
Expand All @@ -690,17 +681,17 @@ func (s *v4Server) setHostname(req, resp *dhcpv4.DHCPv4, lease *Lease) (prev str
lease.Hostname = hostname
}

if requested {
resp.UpdateOption(dhcpv4.OptHostName(lease.Hostname))
}

return prev
}

// processSelecting handles the DHCPREQUEST generated during SELECTING state.
func (s *v4Server) processSelecting(req *dhcpv4.DHCPv4, sid net.IP) (l *Lease, needsReply bool) {
// Client inserts the address of the selected server in 'server identifier',
// 'ciaddr' MUST be zero.
func (s *v4Server) processSelecting(
req *dhcpv4.DHCPv4,
reqIP net.IP,
sid net.IP,
) (l *Lease, needsReply bool) {
// Client inserts the address of the selected server in server identifier,
// ciaddr MUST be zero.
mac := req.ClientHWAddr
if !sid.Equal(s.conf.dnsIPAddrs[0]) {
log.Debug("dhcpv4: bad server identifier in req msg for %s: %s", mac, sid)
Expand All @@ -714,7 +705,6 @@ func (s *v4Server) processSelecting(req *dhcpv4.DHCPv4, sid net.IP) (l *Lease, n

// 'requested IP address' MUST be filled in with the yiaddr value from the
// chosen DHCPOFFER.
reqIP := req.RequestedIPAddress()
if ip4 := reqIP.To4(); ip4 == nil {
log.Debug("dhcpv4: bad requested address in req msg for %s: %s", mac, reqIP)

Expand All @@ -735,15 +725,13 @@ func (s *v4Server) processSelecting(req *dhcpv4.DHCPv4, sid net.IP) (l *Lease, n
func (s *v4Server) processInitReboot(req *dhcpv4.DHCPv4, reqIP net.IP) (l *Lease, needsReply bool) {
mac := req.ClientHWAddr

// 'requested IP address' option MUST be filled in with client's notion of
// its previously assigned address.
if ip4 := reqIP.To4(); ip4 == nil {
log.Debug("dhcpv4: bad requested address in req msg for %s: %s", mac, reqIP)

return nil, false
}

// 'ciaddr' MUST be zero. The client is seeking to verify a previously
// ciaddr MUST be zero. The client is seeking to verify a previously
// allocated, cached configuration.
if ciaddr := req.ClientIPAddr; ciaddr != nil && !ciaddr.IsUnspecified() {
log.Debug("dhcpv4: non-zero ciaddr in init-reboot req msg for %s", mac)
Expand Down Expand Up @@ -778,7 +766,7 @@ func (s *v4Server) processInitReboot(req *dhcpv4.DHCPv4, reqIP net.IP) (l *Lease
func (s *v4Server) processRenew(req *dhcpv4.DHCPv4) (l *Lease, needsReply bool) {
mac := req.ClientHWAddr

// 'ciaddr' MUST be filled in with client's IP address.
// ciaddr MUST be filled in with client's IP address.
ciaddr := req.ClientIPAddr
if ciaddr == nil || ciaddr.IsUnspecified() || ciaddr.To4() == nil {
log.Debug("dhcpv4: bad ciaddr in renew req msg for %s", mac)
Expand All @@ -803,39 +791,54 @@ func (s *v4Server) processRenew(req *dhcpv4.DHCPv4) (l *Lease, needsReply bool)
// processRequest is the handler for a DHCPREQUEST message.
//
// See https://datatracker.ietf.org/doc/html/rfc2131#section-4.3.2.
func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (l *Lease, needsReply bool) {
if sid := req.ServerIdentifier(); sid != nil && !sid.IsUnspecified() {
// If the DHCPREQUEST message contains a 'server identifier' option, the
func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needsReply bool) {
switch reqIP, sid := req.RequestedIPAddress(), req.ServerIdentifier(); {
case sid != nil && !sid.IsUnspecified():
// If the DHCPREQUEST message contains a server identifier option, the
// message is in response to a DHCPOFFER message. Otherwise, the
// message is a request to verify or extend an existing lease.
l, needsReply = s.processSelecting(req, sid)
} else if reqIP := req.RequestedIPAddress(); reqIP != nil && !reqIP.IsUnspecified() {
// The DHCPREQUEST generated during INIT-REBOOT state must not contain a
// 'requested IP address' option.
l, needsReply = s.processInitReboot(req, reqIP)
} else {
// 'server identifier' MUST NOT be filled in, 'requested IP address'
// option MUST NOT be filled in.
l, needsReply = s.processRenew(req)
lease, needsReply = s.processSelecting(req, reqIP, sid)
case reqIP != nil && !reqIP.IsUnspecified():
// Requested IP address option MUST be filled in with client's notion of
// its previously assigned address.
lease, needsReply = s.processInitReboot(req, reqIP)
default:
// Server identifier MUST NOT be filled in, requested IP address option
// MUST NOT be filled in.
lease, needsReply = s.processRenew(req)
}

if l == nil {
if lease == nil {
return nil, needsReply
}

if !l.IsStatic() {
prev := s.setHostname(req, resp, l)
s.commitLease(l, prev)
} else if l.Hostname != "" {
// TODO(e.burkov): This option is used to update the server's DNS
// mapping. The option should only be answered when it has been
// requested.
resp.UpdateOption(OptionFQDN(l.Hostname))
resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeAck))

hostname := req.HostName()
isRequested := hostname != "" || req.ParameterRequestList().Has(dhcpv4.OptionHostName)

s.leasesLock.Lock()
defer s.leasesLock.Unlock()

if lease.IsStatic() {
if lease.Hostname != "" {
// TODO(e.burkov): This option is used to update the server's DNS
// mapping. The option should only be answered when it has been
// requested.
resp.UpdateOption(OptionFQDN(lease.Hostname))
}

return lease, needsReply
}

resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeAck))
prev := s.setHostname(lease, hostname)
s.commitLease(lease, prev)

return l, needsReply
if isRequested {
resp.UpdateOption(dhcpv4.OptHostName(lease.Hostname))
}

return lease, needsReply
}

// processRequest is the handler for the DHCP Decline request.
Expand Down Expand Up @@ -939,6 +942,8 @@ func (s *v4Server) processRelease(req, resp *dhcpv4.DHCPv4) (err error) {
return nil
}

// func (s *v4Server) processByMsgType(req, resp *dhcpv4.DHCPv4) (l *Lease, )

// Find a lease associated with MAC and prepare response
// Return 1: OK
// Return 0: error; reply with Nak
Expand Down

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