Pull request: dhcpd: support decline and release msgs
Updates #3053. Squashed commit of the following: commit eb68a21436536d67b6d23873e6b6f291912bf3a1 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Fri May 14 18:58:15 2021 +0300 dhcpd: do not panic commit 423678934e736e842fc90042ee0037d1efa912ee Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Fri May 14 18:18:49 2021 +0300 dhcpd: support decline and release msgs
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Ainar Garipov
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c890f5c152
commit
9d788a2983
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@ -17,6 +17,10 @@ and this project adheres to
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## [v0.106.3] - 2021-05-17 (APPROX.)
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-->
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### Added
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- Support for DHCP `DECLINE` and `RELEASE` message types ([#3053]).
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### Fixed
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- DHCP leases validation ([#3107], [#3127]).
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@ -26,6 +30,7 @@ and this project adheres to
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- Disallowed domains are now case-insensitive ([#3115]).
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[#2875]: https://github.com/AdguardTeam/AdGuardHome/issues/2875
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[#3053]: https://github.com/AdguardTeam/AdGuardHome/issues/3053
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[#3064]: https://github.com/AdguardTeam/AdGuardHome/issues/3064
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[#3107]: https://github.com/AdguardTeam/AdGuardHome/issues/3107
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[#3115]: https://github.com/AdguardTeam/AdGuardHome/issues/3115
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@ -550,14 +550,30 @@ func (s *v4Server) commitLease(l *Lease) {
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s.conf.notify(LeaseChangedAdded)
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}
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// allocateLease allocates a new lease for the MAC address. If there are no IP
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// addresses left, both l and err are nil.
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func (s *v4Server) allocateLease(mac net.HardwareAddr) (l *Lease, err error) {
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for {
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l, err = s.reserveLease(mac)
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if err != nil {
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return nil, fmt.Errorf("reserving a lease: %w", err)
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} else if l == nil {
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return nil, nil
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}
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if s.addrAvailable(l.IP) {
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return l, nil
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}
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s.blocklistLease(l)
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}
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}
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// processDiscover is the handler for the DHCP Discover request.
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func (s *v4Server) processDiscover(req, resp *dhcpv4.DHCPv4) (l *Lease, err error) {
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mac := req.ClientHWAddr
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err = aghnet.ValidateHardwareAddress(mac)
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if err != nil {
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return nil, err
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}
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defer s.conf.notify(LeaseChangedDBStore)
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s.leasesLock.Lock()
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defer s.leasesLock.Unlock()
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@ -574,36 +590,15 @@ func (s *v4Server) processDiscover(req, resp *dhcpv4.DHCPv4) (l *Lease, err erro
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return l, nil
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}
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needsUpdate := false
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defer func() {
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if needsUpdate {
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s.conf.notify(LeaseChangedDBStore)
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}
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}()
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leaseReady := false
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for !leaseReady {
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l, err = s.reserveLease(mac)
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l, err = s.allocateLease(mac)
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if err != nil {
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return nil, fmt.Errorf("reserving a lease: %w", err)
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}
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if l == nil {
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return nil, err
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} else if l == nil {
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log.Debug("dhcpv4: no more ip addresses")
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return nil, nil
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}
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needsUpdate = true
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if s.addrAvailable(l.IP) {
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leaseReady = true
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} else {
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s.blocklistLease(l)
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l = nil
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}
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}
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resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeOffer))
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return l, nil
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@ -641,11 +636,6 @@ func (o *optFQDN) ToBytes() []byte {
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// processRequest is the handler for the DHCP Request request.
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func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needsReply bool) {
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mac := req.ClientHWAddr
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err := aghnet.ValidateHardwareAddress(mac)
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if err != nil {
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return nil, false
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}
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reqIP := req.RequestedIPAddress()
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if reqIP == nil {
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reqIP = req.ClientIPAddr
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@ -711,7 +701,7 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needs
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}
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s.commitLease(lease)
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} else if len(lease.Hostname) != 0 {
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} else if lease.Hostname != "" {
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o := &optFQDN{
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name: lease.Hostname,
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}
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@ -728,6 +718,107 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needs
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return lease, true
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}
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// processRequest is the handler for the DHCP Decline request.
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func (s *v4Server) processDecline(req, resp *dhcpv4.DHCPv4) (err error) {
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s.conf.notify(LeaseChangedDBStore)
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s.leasesLock.Lock()
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defer s.leasesLock.Unlock()
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mac := req.ClientHWAddr
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reqIP := req.RequestedIPAddress()
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if reqIP == nil {
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reqIP = req.ClientIPAddr
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}
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var oldLease *Lease
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for _, l := range s.leases {
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if bytes.Equal(l.HWAddr, mac) && l.IP.Equal(reqIP) {
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oldLease = l
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break
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}
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}
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if oldLease == nil {
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log.Info("dhcpv4: lease with ip %s for %s not found", reqIP, mac)
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return nil
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}
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err = s.rmDynamicLease(oldLease)
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if err != nil {
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return fmt.Errorf("removing old lease for %s: %w", mac, err)
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}
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newLease, err := s.allocateLease(mac)
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if err != nil {
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return fmt.Errorf("allocating new lease for %s: %w", mac, err)
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} else if newLease == nil {
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log.Info("dhcpv4: allocating new lease for %s: no more ip addresses", mac)
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resp.YourIPAddr = make([]byte, 4)
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resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeAck))
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return nil
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}
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newLease.Hostname = oldLease.Hostname
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newLease.Expiry = time.Now().Add(s.conf.leaseTime)
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err = s.addLease(newLease)
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if err != nil {
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return fmt.Errorf("adding new lease for %s: %w", mac, err)
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}
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log.Info("dhcpv4: changed ip from %s to %s for %s", reqIP, newLease.IP, mac)
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resp.YourIPAddr = make([]byte, 4)
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copy(resp.YourIPAddr, newLease.IP)
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resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeAck))
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return nil
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}
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// processRelease is the handler for the DHCP Release request.
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func (s *v4Server) processRelease(req, resp *dhcpv4.DHCPv4) (err error) {
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mac := req.ClientHWAddr
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reqIP := req.RequestedIPAddress()
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if reqIP == nil {
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reqIP = req.ClientIPAddr
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}
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// TODO(a.garipov): Add a separate notification type for dynamic lease
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// removal?
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defer s.conf.notify(LeaseChangedDBStore)
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n := 0
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s.leasesLock.Lock()
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defer s.leasesLock.Unlock()
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for _, l := range s.leases {
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if !bytes.Equal(l.HWAddr, mac) || !l.IP.Equal(reqIP) {
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continue
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}
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err = s.rmDynamicLease(l)
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if err != nil {
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err = fmt.Errorf("removing dynamic lease for %s: %w", mac, err)
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return
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}
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n++
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}
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log.Info("dhcpv4: released %d dynamic leases for %s", n, mac)
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resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeAck))
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return nil
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}
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// Find a lease associated with MAC and prepare response
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// Return 1: OK
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// Return 0: error; reply with Nak
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@ -737,6 +828,7 @@ func (s *v4Server) process(req, resp *dhcpv4.DHCPv4) int {
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resp.UpdateOption(dhcpv4.OptServerIdentifier(s.conf.dnsIPAddrs[0]))
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// TODO(a.garipov): Refactor this into handlers.
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var l *Lease
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switch req.MessageType() {
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case dhcpv4.MessageTypeDiscover:
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@ -759,10 +851,26 @@ func (s *v4Server) process(req, resp *dhcpv4.DHCPv4) int {
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}
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return -1 // drop packet
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}
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case dhcpv4.MessageTypeDecline:
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err = s.processDecline(req, resp)
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if err != nil {
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log.Error("dhcpv4: processing decline: %s", err)
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return 0
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}
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case dhcpv4.MessageTypeRelease:
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err = s.processRelease(req, resp)
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if err != nil {
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log.Error("dhcpv4: processing release: %s", err)
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return 0
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}
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}
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if l != nil {
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resp.YourIPAddr = make([]byte, 4)
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copy(resp.YourIPAddr, l.IP)
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}
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resp.UpdateOption(dhcpv4.OptIPAddressLeaseTime(s.conf.leaseTime))
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resp.UpdateOption(dhcpv4.OptRouter(s.conf.subnet.IP))
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@ -785,11 +893,13 @@ func (s *v4Server) packetHandler(conn net.PacketConn, peer net.Addr, req *dhcpv4
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switch req.MessageType() {
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case dhcpv4.MessageTypeDiscover,
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dhcpv4.MessageTypeRequest:
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//
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dhcpv4.MessageTypeRequest,
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dhcpv4.MessageTypeDecline,
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dhcpv4.MessageTypeRelease:
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// Go on.
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default:
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log.Debug("dhcpv4: unsupported message type %d", req.MessageType())
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return
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}
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