Pull request: dhcpd: refactor validations
Updates #3107. Updates #3127. Squashed commit of the following: commit ad64472566ecd1b0864212cd2644a57439aceb85 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Thu May 13 14:45:21 2021 +0300 dhcpd: refactor validations
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Ainar Garipov
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1b789b5f81
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c890f5c152
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@ -19,6 +19,7 @@ and this project adheres to
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### Fixed
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- DHCP leases validation ([#3107], [#3127]).
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- Local PTR request recursion in Docker containers ([#3064]).
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- Ignoring client-specific filtering settings when filtering is disabled in
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general settings ([#2875]).
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@ -26,7 +27,9 @@ and this project adheres to
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[#2875]: https://github.com/AdguardTeam/AdGuardHome/issues/2875
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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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[#3127]: https://github.com/AdguardTeam/AdGuardHome/issues/3127
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@ -73,42 +73,26 @@ func normalizeHostname(hostname string) (norm string, err error) {
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return norm, nil
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}
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// validHostnameForClient accepts the hostname sent by the client and returns
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// either a normalized version of that hostname or a new hostname generated from
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// the client's IP address. If this new hostname is different from the provided
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// previous hostname, additional uniqueness check is performed.
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//
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// hostname is always a non-empty valid hostname. If err is not nil, it
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// describes the issues encountered when normalizing cliHostname.
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func (s *v4Server) validHostnameForClient(
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cliHostname string,
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prevHostname string,
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ip net.IP,
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) (hostname string, err error) {
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hostname, err = normalizeHostname(cliHostname)
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if err == nil && hostname != "" {
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err = aghnet.ValidateDomainName(hostname)
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if err != nil {
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// Go on and assign a hostname made from the IP below,
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// returning the error that we've got.
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hostname = ""
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} else if hostname != prevHostname && s.leaseHosts.Has(hostname) {
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// Go on and assign a unique hostname made from the IP
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// below, returning the error about uniqueness.
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err = agherr.Error("hostname exists")
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hostname = ""
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}
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// validHostnameForClient accepts the hostname sent by the client and its IP and
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// returns either a normalized version of that hostname, or a new hostname
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// generated from the IP address, or an empty string.
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func (s *v4Server) validHostnameForClient(cliHostname string, ip net.IP) (hostname string) {
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hostname, err := normalizeHostname(cliHostname)
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if err != nil {
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log.Info("dhcpv4: %s", err)
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}
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if hostname == "" {
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hostname = aghnet.GenerateHostname(ip)
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}
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if hostname != cliHostname {
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log.Info("dhcpv4: normalized hostname %q into %q", cliHostname, hostname)
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err = aghnet.ValidateDomainName(hostname)
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if err != nil {
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log.Info("dhcpv4: %s", err)
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hostname = ""
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}
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return hostname, err
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return hostname
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}
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// ResetLeases - reset leases
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@ -124,15 +108,7 @@ func (s *v4Server) ResetLeases(leases []*Lease) {
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s.leases = nil
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for _, l := range leases {
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l.Hostname, err = s.validHostnameForClient(l.Hostname, l.Hostname, l.IP)
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if err != nil {
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log.Info(
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"dhcpv4: warning: previous hostname %q is invalid: %s",
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l.Hostname,
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err,
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)
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}
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l.Hostname = s.validHostnameForClient(l.Hostname, l.IP)
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err = s.addLease(l)
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if err != nil {
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// TODO(a.garipov): Wrap and bubble up the error.
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@ -287,6 +263,15 @@ func (s *v4Server) rmDynamicLease(lease *Lease) (err error) {
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}
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s.rmLeaseByIndex(i)
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if i == len(s.leases) {
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break
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}
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l = s.leases[i]
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}
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if l.Hostname == lease.Hostname {
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l.Hostname = ""
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}
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}
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@ -352,22 +337,25 @@ func (s *v4Server) AddStaticLease(l Lease) (err error) {
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return err
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}
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var hostname string
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hostname, err = normalizeHostname(l.Hostname)
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if err != nil {
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return err
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}
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if l.Hostname != "" {
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var hostname string
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hostname, err = normalizeHostname(l.Hostname)
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if err != nil {
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return err
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}
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err = aghnet.ValidateDomainName(hostname)
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if err != nil {
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return fmt.Errorf("validating hostname: %w", err)
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}
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err = aghnet.ValidateDomainName(hostname)
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if err != nil {
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return fmt.Errorf("validating hostname: %w", err)
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}
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if s.leaseHosts.Has(hostname) {
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return agherr.Error("hostname exists")
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}
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// Don't check for hostname uniqueness, since we try to emulate
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// dnsmasq here, which means that rmDynamicLease below will
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// simply empty the hostname of the dynamic lease if there even
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// is one.
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l.Hostname = hostname
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l.Hostname = hostname
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}
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// Perform the following actions in an anonymous function to make sure
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// that the lock gets unlocked before the notification step.
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@ -553,7 +541,10 @@ func (s *v4Server) commitLease(l *Lease) {
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defer s.leasesLock.Unlock()
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s.conf.notify(LeaseChangedDBStore)
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s.leaseHosts.Add(l.Hostname)
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if l.Hostname != "" {
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s.leaseHosts.Add(l.Hostname)
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}
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}()
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s.conf.notify(LeaseChangedAdded)
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@ -647,7 +638,7 @@ func (o *optFQDN) ToBytes() []byte {
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return b
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}
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// processDiscover is the handler for the DHCP Request request.
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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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@ -662,13 +653,13 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needs
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sid := req.ServerIdentifier()
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if len(sid) != 0 && !sid.Equal(s.conf.dnsIPAddrs[0]) {
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log.Debug("dhcpv4: bad OptionServerIdentifier in request message for %s", mac)
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log.Debug("dhcpv4: bad OptionServerIdentifier in req msg for %s", mac)
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return nil, false
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}
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if ip4 := reqIP.To4(); ip4 == nil {
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log.Debug("dhcpv4: bad OptionRequestedIPAddress in request message for %s", mac)
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log.Debug("dhcpv4: bad OptionRequestedIPAddress in req msg for %s", mac)
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return nil, false
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}
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@ -685,15 +676,17 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needs
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if l.IP.Equal(reqIP) {
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lease = l
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} else {
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log.Debug(
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`dhcpv4: mismatched OptionRequestedIPAddress `+
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`in request message for %s`,
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mac,
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)
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mismatch = true
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return
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}
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log.Debug(
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`dhcpv4: mismatched OptionRequestedIPAddress in req msg for %s`,
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mac,
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)
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mismatch = true
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return
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}
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}()
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@ -709,13 +702,12 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needs
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if !lease.IsStatic() {
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cliHostname := req.HostName()
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lease.Hostname, err = s.validHostnameForClient(cliHostname, lease.Hostname, reqIP)
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if err != nil {
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log.Info(
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"dhcpv4: warning: client hostname %q is invalid: %s",
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cliHostname,
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err,
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)
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hostname := s.validHostnameForClient(cliHostname, reqIP)
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if hostname != lease.Hostname && s.leaseHosts.Has(hostname) {
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log.Info("dhcpv4: hostname %q already exists", hostname)
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lease.Hostname = ""
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} else {
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lease.Hostname = hostname
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}
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s.commitLease(lease)
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