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Pull request: * dhcpd: send secondary dns as well

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Merge in DNS/adguard-home from 1708-secondary-dns to master

Updates #1708.

Squashed commit of the following:

commit 4529452e31131763f00c9c834cc95638f1a3d142
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Nov 9 18:12:57 2020 +0300

    * dhcpd: send secondary dns as well
This commit is contained in:
Ainar Garipov 2020-11-09 19:27:04 +03:00
parent 1e583315a8
commit 3cc5bf210d
5 changed files with 152 additions and 85 deletions
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105
internal/dhcpd/check_other_dhcp.go
View file

@ -26,12 +26,16 @@ func CheckIfOtherDHCPServersPresentV4(ifaceName string) (bool, error) {
return false, fmt.Errorf("couldn't find interface by name %s: %w", ifaceName, err)
}
// get ipv4 address of an interface
ifaceIPNet := getIfaceIPv4(*iface)
ifaceIPNet, err := ifaceIPv4Addrs(iface)
if err != nil {
return false, fmt.Errorf("getting ipv4 addrs for iface %s: %w", ifaceName, err)
}
if len(ifaceIPNet) == 0 {
return false, fmt.Errorf("couldn't find IPv4 address of interface %s %+v", ifaceName, iface)
return false, fmt.Errorf("interface %s has no ipv4 addresses", ifaceName)
}
// TODO(a.garipov): Find out what this is about. Perhaps this
// information is outdated or at least incomplete.
if runtime.GOOS == "darwin" {
return false, fmt.Errorf("can't find DHCP server: not supported on macOS")
}
@ -82,46 +86,66 @@ func CheckIfOtherDHCPServersPresentV4(ifaceName string) (bool, error) {
}
for {
// wait for answer
log.Tracef("Waiting %v for an answer", defaultDiscoverTime)
// TODO: replicate dhclient's behaviour of retrying several times with progressively bigger timeouts
b := make([]byte, 1500)
_ = c.SetReadDeadline(time.Now().Add(defaultDiscoverTime))
n, _, err := c.ReadFrom(b)
if isTimeout(err) {
// timed out -- no DHCP servers
log.Debug("DHCPv4: didn't receive DHCP response")
return false, nil
}
if err != nil {
return false, fmt.Errorf("couldn't receive packet: %w", err)
}
log.Tracef("Received packet (%v bytes)", n)
response, err := dhcpv4.FromBytes(b[:n])
if err != nil {
log.Debug("DHCPv4: dhcpv4.FromBytes: %s", err)
ok, next, err := tryConn(req, c, iface)
if next {
continue
}
log.Debug("DHCPv4: received message from server: %s", response.Summary())
if !(response.OpCode == dhcpv4.OpcodeBootReply &&
response.HWType == iana.HWTypeEthernet &&
bytes.Equal(response.ClientHWAddr, iface.HardwareAddr) &&
bytes.Equal(response.TransactionID[:], req.TransactionID[:]) &&
response.Options.Has(dhcpv4.OptionDHCPMessageType)) {
log.Debug("DHCPv4: received message from server doesn't match our request")
continue
if ok {
return true, nil
}
if err != nil {
log.Debug("%s", err)
}
log.Tracef("The packet is from an active DHCP server")
// that's a DHCP server there
return true, nil
}
}
// TODO(a.garipov): Refactor further. Inspect error handling, remove the next
// parameter, address the TODO, etc.
func tryConn(req *dhcpv4.DHCPv4, c net.PacketConn, iface *net.Interface) (ok, next bool, err error) {
// TODO: replicate dhclient's behavior of retrying several times with
// progressively longer timeouts.
log.Tracef("waiting %v for an answer", defaultDiscoverTime)
b := make([]byte, 1500)
_ = c.SetReadDeadline(time.Now().Add(defaultDiscoverTime))
n, _, err := c.ReadFrom(b)
if err != nil {
if isTimeout(err) {
log.Debug("dhcpv4: didn't receive dhcp response")
return false, false, nil
}
return false, false, fmt.Errorf("receiving packet: %w", err)
}
log.Tracef("received packet, %d bytes", n)
response, err := dhcpv4.FromBytes(b[:n])
if err != nil {
log.Debug("dhcpv4: encoding: %s", err)
return false, true, err
}
log.Debug("dhcpv4: received message from server: %s", response.Summary())
if !(response.OpCode == dhcpv4.OpcodeBootReply &&
response.HWType == iana.HWTypeEthernet &&
bytes.Equal(response.ClientHWAddr, iface.HardwareAddr) &&
bytes.Equal(response.TransactionID[:], req.TransactionID[:]) &&
response.Options.Has(dhcpv4.OptionDHCPMessageType)) {
log.Debug("dhcpv4: received message from server doesn't match our request")
return false, true, nil
}
log.Tracef("the packet is from an active dhcp server")
return true, false, nil
}
// CheckIfOtherDHCPServersPresentV6 sends a DHCP request to the specified network interface,
// and waits for a response for a period defined by defaultDiscoverTime
func CheckIfOtherDHCPServersPresentV6(ifaceName string) (bool, error) {
@ -130,9 +154,12 @@ func CheckIfOtherDHCPServersPresentV6(ifaceName string) (bool, error) {
return false, fmt.Errorf("dhcpv6: net.InterfaceByName: %s: %w", ifaceName, err)
}
ifaceIPNet := getIfaceIPv6(*iface)
ifaceIPNet, err := ifaceIPv6Addrs(iface)
if err != nil {
return false, fmt.Errorf("getting ipv6 addrs for iface %s: %w", ifaceName, err)
}
if len(ifaceIPNet) == 0 {
return false, fmt.Errorf("dhcpv6: couldn't find IPv6 address of interface %s %+v", ifaceName, iface)
return false, fmt.Errorf("interface %s has no ipv6 addresses", ifaceName)
}
srcIP := ifaceIPNet[0]

2
internal/dhcpd/dhcp_http.go
View file

@ -335,7 +335,7 @@ func (s *Server) handleDHCPFindActiveServer(w http.ResponseWriter, r *http.Reque
foundVal := "no"
if found4 {
foundVal = "yes"
} else if err != nil {
} else if err4 != nil {
foundVal = "error"
othSrv["error"] = err4.Error()
}

20
internal/dhcpd/helpers.go
View file

@ -14,26 +14,6 @@ func isTimeout(err error) bool {
return operr.Timeout()
}
// Get IPv4 address list
func getIfaceIPv4(iface net.Interface) []net.IP {
addrs, err := iface.Addrs()
if err != nil {
return nil
}
var res []net.IP
for _, a := range addrs {
ipnet, ok := a.(*net.IPNet)
if !ok {
continue
}
if ipnet.IP.To4() != nil {
res = append(res, ipnet.IP.To4())
}
}
return res
}
func parseIPv4(text string) (net.IP, error) {
result := net.ParseIP(text)
if result == nil {

64
internal/dhcpd/v4.go
View file

@ -36,7 +36,7 @@ func (s *v4Server) WriteDiskConfig6(c *V6ServerConf) {
}
// Return TRUE if IP address is within range [start..stop]
func ip4InRange(start net.IP, stop net.IP, ip net.IP) bool {
func ip4InRange(start, stop, ip net.IP) bool {
if len(start) != 4 || len(stop) != 4 {
return false
}
@ -335,7 +335,7 @@ func (s *v4Server) commitLease(l *Lease) {
}
// Process Discover request and return lease
func (s *v4Server) processDiscover(req *dhcpv4.DHCPv4, resp *dhcpv4.DHCPv4) *Lease {
func (s *v4Server) processDiscover(req, resp *dhcpv4.DHCPv4) *Lease {
mac := req.ClientHWAddr
s.leasesLock.Lock()
@ -409,7 +409,7 @@ func (o *optFQDN) ToBytes() []byte {
// Process Request request and return lease
// Return false if we don't need to reply
func (s *v4Server) processRequest(req *dhcpv4.DHCPv4, resp *dhcpv4.DHCPv4) (*Lease, bool) {
func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (*Lease, bool) {
var lease *Lease
mac := req.ClientHWAddr
hostname := req.Options.Get(dhcpv4.OptionHostName)
@ -472,7 +472,7 @@ func (s *v4Server) processRequest(req *dhcpv4.DHCPv4, resp *dhcpv4.DHCPv4) (*Lea
// Return 1: OK
// Return 0: error; reply with Nak
// Return -1: error; don't reply
func (s *v4Server) process(req *dhcpv4.DHCPv4, resp *dhcpv4.DHCPv4) int {
func (s *v4Server) process(req, resp *dhcpv4.DHCPv4) int {
var lease *Lease
resp.UpdateOption(dhcpv4.OptServerIdentifier(s.conf.dnsIPAddrs[0]))
@ -554,24 +554,65 @@ func (s *v4Server) packetHandler(conn net.PacketConn, peer net.Addr, req *dhcpv4
}
}
// Start - start server
// ifaceIPv4Addrs returns the interface's IPv4 addresses.
func ifaceIPv4Addrs(iface *net.Interface) (ips []net.IP, err error) {
addrs, err := iface.Addrs()
if err != nil {
return nil, err
}
for _, a := range addrs {
ipnet, ok := a.(*net.IPNet)
if !ok {
continue
}
if ip := ipnet.IP.To4(); ip != nil {
ips = append(ips, ip)
}
}
return ips, nil
}
// Start starts the IPv4 DHCP server.
func (s *v4Server) Start() error {
if !s.conf.Enabled {
return nil
}
iface, err := net.InterfaceByName(s.conf.InterfaceName)
ifaceName := s.conf.InterfaceName
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
return fmt.Errorf("dhcpv4: Couldn't find interface by name %s: %w", s.conf.InterfaceName, err)
return fmt.Errorf("dhcpv4: finding interface %s by name: %w", ifaceName, err)
}
log.Debug("dhcpv4: starting...")
s.conf.dnsIPAddrs = getIfaceIPv4(*iface)
if len(s.conf.dnsIPAddrs) == 0 {
log.Debug("dhcpv4: no IPv6 address for interface %s", iface.Name)
return nil
dnsIPAddrs, err := ifaceIPv4Addrs(iface)
if err != nil {
return fmt.Errorf("dhcpv4: getting ipv4 addrs for iface %s: %w", ifaceName, err)
}
switch len(dnsIPAddrs) {
case 0:
log.Debug("dhcpv4: no ipv4 address for interface %s", iface.Name)
return nil
case 1:
// Some Android devices use 8.8.8.8 if there is no secondary DNS
// server. Fix that by setting the secondary DNS address to our
// address as well.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/1708.
log.Debug("dhcpv4: setting secondary dns ip to iself for interface %s", iface.Name)
dnsIPAddrs = append(dnsIPAddrs, dnsIPAddrs[0])
default:
// Go on.
}
s.conf.dnsIPAddrs = dnsIPAddrs
laddr := &net.UDPAddr{
IP: net.ParseIP("0.0.0.0"),
Port: dhcpv4.ServerPort,
@ -587,6 +628,7 @@ func (s *v4Server) Start() error {
err = s.srv.Serve()
log.Debug("dhcpv4: srv.Serve: %s", err)
}()
return nil
}

46
internal/dhcpd/v6.go
View file

@ -537,24 +537,25 @@ func (s *v6Server) packetHandler(conn net.PacketConn, peer net.Addr, req dhcpv6.
}
}
// Get IPv6 address list
func getIfaceIPv6(iface net.Interface) []net.IP {
// ifaceIPv6Addrs returns the interface's IPv6 addresses.
func ifaceIPv6Addrs(iface *net.Interface) (ips []net.IP, err error) {
addrs, err := iface.Addrs()
if err != nil {
return nil
return nil, err
}
var res []net.IP
for _, a := range addrs {
ipnet, ok := a.(*net.IPNet)
if !ok {
continue
}
if ipnet.IP.To4() == nil {
res = append(res, ipnet.IP)
if ip := ipnet.IP.To16(); ip != nil {
ips = append(ips, ip)
}
}
return res
return ips, nil
}
// initialize RA module
@ -578,23 +579,40 @@ func (s *v6Server) initRA(iface *net.Interface) error {
return s.ra.Init()
}
// Start - start server
// Start starts the IPv6 DHCP server.
func (s *v6Server) Start() error {
if !s.conf.Enabled {
return nil
}
iface, err := net.InterfaceByName(s.conf.InterfaceName)
ifaceName := s.conf.InterfaceName
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
return fmt.Errorf("couldn't find interface by name %s: %w", s.conf.InterfaceName, err)
return fmt.Errorf("dhcpv6: finding interface %s by name: %w", ifaceName, err)
}
s.conf.dnsIPAddrs = getIfaceIPv6(*iface)
if len(s.conf.dnsIPAddrs) == 0 {
log.Debug("DHCPv6: no IPv6 address for interface %s", iface.Name)
return nil
log.Debug("dhcpv4: starting...")
dnsIPAddrs, err := ifaceIPv6Addrs(iface)
if err != nil {
return fmt.Errorf("dhcpv6: getting ipv6 addrs for iface %s: %w", ifaceName, err)
}
switch len(dnsIPAddrs) {
case 0:
log.Debug("dhcpv6: no ipv6 address for interface %s", iface.Name)
return nil
case 1:
// See the comment in (*v4Server).Start.
log.Debug("dhcpv6: setting secondary dns ip to iself for interface %s", iface.Name)
dnsIPAddrs = append(dnsIPAddrs, dnsIPAddrs[0])
default:
// Go on.
}
s.conf.dnsIPAddrs = dnsIPAddrs
err = s.initRA(iface)
if err != nil {
return err