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Pull request: 4745 Fix DHCP hostnames

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Merge in DNS/adguard-home from 4745-fix-dhcp-hostnames to master

Closes #4745.

Squashed commit of the following:

commit fe03c8eda6c8ee35a10eb5f5a8e4d4d0c7373246
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Aug 23 18:16:16 2022 +0300

    dhcpd: imp code, naming

commit 7a7129268917d99ba16781b7f2e9bfb7ae84ff3e
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Aug 23 18:10:12 2022 +0300

    dhcpd: add tests

commit bb14a4a62df1eed6492d30f622c3e22da9a6f4be
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Aug 23 14:58:29 2022 +0300

    dhcpd: imp code, docs

commit 2ada39f994cb9dbb2208d47a588eb72056bb5306
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Aug 23 14:44:35 2022 +0300

    all: log changes

commit cbd3ed254865921be09376097dac9f5926b2349a
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Aug 23 14:40:54 2022 +0300

    dhcpd: imp option 81

commit 64dabb52560f5edc08f17aadaa43172a5d74463d
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Aug 23 14:10:15 2022 +0300

    dhcpd: fix empty hostname in static lease

commit 0df5d10d0d94863b9bbab28129bcc3436fb71222
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Aug 23 13:34:31 2022 +0300

    dhcpd: report dupl hostnames of static lease
This commit is contained in:
Eugene Burkov
2022-08-23 18:22:49 +03:00
parent 307654f648
commit bdcf345155
3 changed files with 201 additions and 70 deletions
Download Patch File Download Diff File Expand all files Collapse all files

123
internal/dhcpd/v4.go
View File

@@ -20,6 +20,7 @@ import (
"github.com/go-ping/ping"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/insomniacslk/dhcp/dhcpv4/server4"
"golang.org/x/exp/slices"
//lint:ignore SA1019 See the TODO in go.mod.
"github.com/mdlayher/raw"
@@ -93,6 +94,9 @@ func (s *v4Server) validHostnameForClient(cliHostname string, ip net.IP) (hostna
if hostname == "" {
hostname = aghnet.GenerateHostname(ip)
} else if s.leaseHosts.Has(hostname) {
log.Info("dhcpv4: hostname %q already exists", hostname)
hostname = aghnet.GenerateHostname(ip)
}
err = netutil.ValidateDomainName(hostname)
@@ -252,11 +256,11 @@ func (s *v4Server) rmLeaseByIndex(i int) {
// Remove a dynamic lease with the same properties
// Return error if a static lease is found
func (s *v4Server) rmDynamicLease(lease *Lease) (err error) {
for i := 0; i < len(s.leases); i++ {
l := s.leases[i]
for i, l := range s.leases {
isStatic := l.IsStatic()
if bytes.Equal(l.HWAddr, lease.HWAddr) {
if l.IsStatic() {
if bytes.Equal(l.HWAddr, lease.HWAddr) || l.IP.Equal(lease.IP) {
if isStatic {
return errors.Error("static lease already exists")
}
@@ -268,20 +272,7 @@ func (s *v4Server) rmDynamicLease(lease *Lease) (err error) {
l = s.leases[i]
}
if l.IP.Equal(lease.IP) {
if l.IsStatic() {
return errors.Error("static lease already exists")
}
s.rmLeaseByIndex(i)
if i == len(s.leases) {
break
}
l = s.leases[i]
}
if l.Hostname == lease.Hostname {
if !isStatic && l.Hostname == lease.Hostname {
l.Hostname = ""
}
}
@@ -289,6 +280,10 @@ func (s *v4Server) rmDynamicLease(lease *Lease) (err error) {
return nil
}
// ErrDupHostname is returned by addLease when the added lease has a not empty
// non-unique hostname.
const ErrDupHostname = errors.Error("hostname is not unique")
// addLease adds a dynamic or static lease.
func (s *v4Server) addLease(l *Lease) (err error) {
r := s.conf.ipRange
@@ -304,13 +299,17 @@ func (s *v4Server) addLease(l *Lease) (err error) {
return fmt.Errorf("lease %s (%s) out of range, not adding", l.IP, l.HWAddr)
}
s.leases = append(s.leases, l)
s.leasedOffsets.set(offset, true)
if l.Hostname != "" {
if s.leaseHosts.Has(l.Hostname) {
return ErrDupHostname
}
s.leaseHosts.Add(l.Hostname)
}
s.leases = append(s.leases, l)
s.leasedOffsets.set(offset, true)
return nil
}
@@ -365,10 +364,11 @@ func (s *v4Server) AddStaticLease(l *Lease) (err error) {
return fmt.Errorf("validating hostname: %w", err)
}
// Don't check for hostname uniqueness, since we try to emulate
// dnsmasq here, which means that rmDynamicLease below will
// simply empty the hostname of the dynamic lease if there even
// is one.
// Don't check for hostname uniqueness, since we try to emulate dnsmasq
// here, which means that rmDynamicLease below will simply empty the
// hostname of the dynamic lease if there even is one. In case a static
// lease with the same name already exists, addLease will return an
// error and the lease won't be added.
l.Hostname = hostname
}
@@ -523,11 +523,7 @@ func (s *v4Server) findExpiredLease() int {
// reserveLease reserves a lease for a client by its MAC-address. It returns
// nil if it couldn't allocate a new lease.
func (s *v4Server) reserveLease(mac net.HardwareAddr) (l *Lease, err error) {
l = &Lease{
HWAddr: make([]byte, len(mac)),
}
copy(l.HWAddr, mac)
l = &Lease{HWAddr: slices.Clone(mac)}
l.IP = s.nextIP()
if l.IP == nil {
@@ -620,33 +616,25 @@ func (s *v4Server) processDiscover(req, resp *dhcpv4.DHCPv4) (l *Lease, err erro
return l, nil
}
type optFQDN struct {
name string
}
// OptionFQDN returns a DHCPv4 option for sending the FQDN to the client
// requested another hostname.
//
// See https://datatracker.ietf.org/doc/html/rfc4702.
func OptionFQDN(fqdn string) (opt dhcpv4.Option) {
optData := []byte{
// Set only S and O DHCP client FQDN option flags.
//
// See https://datatracker.ietf.org/doc/html/rfc4702#section-2.1.
1<<0 | 1<<1,
// The RCODE fields should be set to 0xFF in the server responses.
//
// See https://datatracker.ietf.org/doc/html/rfc4702#section-2.2.
0xFF,
0xFF,
}
optData = append(optData, fqdn...)
func (o *optFQDN) String() string {
return "optFQDN"
}
// flags[1]
// A-RR[1]
// PTR-RR[1]
// name[]
func (o *optFQDN) ToBytes() []byte {
b := make([]byte, 3+len(o.name))
i := 0
b[i] = 0x03 // f_server_overrides | f_server
i++
b[i] = 255 // A-RR
i++
b[i] = 255 // PTR-RR
i++
copy(b[i:], []byte(o.name))
return b
return dhcpv4.OptGeneric(dhcpv4.OptionFQDN, optData)
}
// checkLease checks if the pair of mac and ip is already leased. The mismatch
@@ -679,6 +667,8 @@ func (s *v4Server) checkLease(mac net.HardwareAddr, ip net.IP) (lease *Lease, mi
// processRequest is the handler for the DHCP Request request.
func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needsReply bool) {
mac := req.ClientHWAddr
// TODO(e.burkov): The IP address can only be requested in DHCPDISCOVER
// message.
reqIP := req.RequestedIPAddress()
if reqIP == nil {
reqIP = req.ClientIPAddr
@@ -711,24 +701,17 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, needs
if !lease.IsStatic() {
cliHostname := req.HostName()
hostname := s.validHostnameForClient(cliHostname, reqIP)
if hostname != lease.Hostname && s.leaseHosts.Has(hostname) {
log.Info("dhcpv4: hostname %q already exists", hostname)
lease.Hostname = ""
} else {
if lease.Hostname != hostname {
lease.Hostname = hostname
resp.UpdateOption(dhcpv4.OptHostName(hostname))
}
s.commitLease(lease)
} else if lease.Hostname != "" {
o := &optFQDN{
name: lease.Hostname,
}
fqdn := dhcpv4.Option{
Code: dhcpv4.OptionFQDN,
Value: o,
}
resp.UpdateOption(fqdn)
// 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))
}
resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeAck))
@@ -851,7 +834,7 @@ func (s *v4Server) process(req, resp *dhcpv4.DHCPv4) int {
// TODO(a.garipov): Refactor this into handlers.
var l *Lease
switch req.MessageType() {
switch mt := req.MessageType(); mt {
case dhcpv4.MessageTypeDiscover:
l, err = s.processDiscover(req, resp)
if err != nil {