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Merge with master

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This commit is contained in:
Andrey Meshkov
2019-03-22 10:36:48 +03:00
parent bd31151c1f 5b417d9f17
commit 7ebfaccc6e
76 changed files with 3489 additions and 1135 deletions
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355
dhcpd/dhcpd.go
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@@ -4,11 +4,13 @@ import (
"bytes"
"fmt"
"net"
"strings"
"sync"
"time"
"github.com/hmage/golibs/log"
"github.com/AdguardTeam/golibs/log"
"github.com/krolaw/dhcp4"
ping "github.com/sparrc/go-ping"
)
const defaultDiscoverTime = time.Second * 3
@@ -32,6 +34,10 @@ type ServerConfig struct {
RangeStart string `json:"range_start" yaml:"range_start"`
RangeEnd string `json:"range_end" yaml:"range_end"`
LeaseDuration uint `json:"lease_duration" yaml:"lease_duration"` // in seconds
// IP conflict detector: time (ms) to wait for ICMP reply.
// 0: disable
ICMPTimeout uint `json:"icmp_timeout_msec" yaml:"icmp_timeout_msec"`
}
// Server - the current state of the DHCP server
@@ -40,6 +46,11 @@ type Server struct {
ipnet *net.IPNet // if interface name changes, this needs to be reset
cond *sync.Cond // Synchronize worker thread with main thread
mutex sync.Mutex // Mutex for 'cond'
running bool // Set if the worker thread is running
stopping bool // Set if the worker thread should be stopped
// leases
leases []*Lease
leaseStart net.IP // parsed from config RangeStart
@@ -54,6 +65,16 @@ type Server struct {
sync.RWMutex
}
// Print information about the available network interfaces
func printInterfaces() {
ifaces, _ := net.Interfaces()
var buf strings.Builder
for i := range ifaces {
buf.WriteString(fmt.Sprintf("\"%s\", ", ifaces[i].Name))
}
log.Info("Available network interfaces: %s", buf.String())
}
// Start will listen on port 67 and serve DHCP requests.
// Even though config can be nil, it is not optional (at least for now), since there are no default values (yet).
func (s *Server) Start(config *ServerConfig) error {
@@ -64,6 +85,7 @@ func (s *Server) Start(config *ServerConfig) error {
iface, err := net.InterfaceByName(s.InterfaceName)
if err != nil {
s.closeConn() // in case it was already started
printInterfaces()
return wrapErrPrint(err, "Couldn't find interface by name %s", s.InterfaceName)
}
@@ -122,20 +144,27 @@ func (s *Server) Start(config *ServerConfig) error {
s.closeConn()
}
s.dbLoad()
c, err := newFilterConn(*iface, ":67") // it has to be bound to 0.0.0.0:67, otherwise it won't see DHCP discover/request packets
if err != nil {
return wrapErrPrint(err, "Couldn't start listening socket on 0.0.0.0:67")
}
log.Info("DHCP: listening on 0.0.0.0:67")
s.conn = c
s.cond = sync.NewCond(&s.mutex)
s.running = true
go func() {
// operate on c instead of c.conn because c.conn can change over time
err := dhcp4.Serve(c, s)
if err != nil {
if err != nil && !s.stopping {
log.Printf("dhcp4.Serve() returned with error: %s", err)
}
c.Close() // in case Serve() exits for other reason than listening socket closure
s.running = false
s.cond.Signal()
}()
return nil
@@ -147,11 +176,23 @@ func (s *Server) Stop() error {
// nothing to do, return silently
return nil
}
s.stopping = true
err := s.closeConn()
if err != nil {
return wrapErrPrint(err, "Couldn't close UDP listening socket")
}
// We've just closed the listening socket.
// Worker thread should exit right after it tries to read from the socket.
s.mutex.Lock()
for s.running {
s.cond.Wait()
}
s.mutex.Unlock()
s.dbStore()
return nil
}
@@ -165,6 +206,7 @@ func (s *Server) closeConn() error {
return err
}
// Reserve a lease for the client
func (s *Server) reserveLease(p dhcp4.Packet) (*Lease, error) {
// WARNING: do not remove copy()
// the given hwaddr by p.CHAddr() in the packet survives only during ServeDHCP() call
@@ -172,27 +214,39 @@ func (s *Server) reserveLease(p dhcp4.Packet) (*Lease, error) {
hwaddrCOW := p.CHAddr()
hwaddr := make(net.HardwareAddr, len(hwaddrCOW))
copy(hwaddr, hwaddrCOW)
foundLease := s.locateLease(p)
if foundLease != nil {
// log.Tracef("found lease for %s: %+v", hwaddr, foundLease)
return foundLease, nil
}
// not assigned a lease, create new one, find IP from LRU
hostname := p.ParseOptions()[dhcp4.OptionHostName]
lease := &Lease{HWAddr: hwaddr, Hostname: string(hostname)}
log.Tracef("Lease not found for %s: creating new one", hwaddr)
ip, err := s.findFreeIP(hwaddr)
if err != nil {
return nil, wrapErrPrint(err, "Couldn't find free IP for the lease %s", hwaddr.String())
i := s.findExpiredLease()
if i < 0 {
return nil, wrapErrPrint(err, "Couldn't find free IP for the lease %s", hwaddr.String())
}
log.Tracef("Assigning IP address %s to %s (lease for %s expired at %s)",
s.leases[i].IP, hwaddr, s.leases[i].HWAddr, s.leases[i].Expiry)
lease.IP = s.leases[i].IP
s.Lock()
s.leases[i] = lease
s.Unlock()
s.reserveIP(lease.IP, hwaddr)
return lease, nil
}
log.Tracef("Assigning to %s IP address %s", hwaddr, ip.String())
hostname := p.ParseOptions()[dhcp4.OptionHostName]
lease := &Lease{HWAddr: hwaddr, IP: ip, Hostname: string(hostname)}
lease.IP = ip
s.Lock()
s.leases = append(s.leases, lease)
s.Unlock()
return lease, nil
}
func (s *Server) locateLease(p dhcp4.Packet) *Lease {
// Find a lease for the client
func (s *Server) findLease(p dhcp4.Packet) *Lease {
hwaddr := p.CHAddr()
for i := range s.leases {
if bytes.Equal([]byte(hwaddr), []byte(s.leases[i].HWAddr)) {
@@ -203,6 +257,17 @@ func (s *Server) locateLease(p dhcp4.Packet) *Lease {
return nil
}
// Find an expired lease and return its index or -1
func (s *Server) findExpiredLease() int {
now := time.Now().Unix()
for i, lease := range s.leases {
if lease.Expiry.Unix() <= now {
return i
}
}
return -1
}
func (s *Server) findFreeIP(hwaddr net.HardwareAddr) (net.IP, error) {
// if IP pool is nil, lazy initialize it
if s.IPpool == nil {
@@ -213,13 +278,12 @@ func (s *Server) findFreeIP(hwaddr net.HardwareAddr) (net.IP, error) {
var foundIP net.IP
for i := 0; i < dhcp4.IPRange(s.leaseStart, s.leaseStop); i++ {
newIP := dhcp4.IPAdd(s.leaseStart, i)
foundHWaddr := s.getIPpool(newIP)
foundHWaddr := s.findReservedHWaddr(newIP)
log.Tracef("tried IP %v, got hwaddr %v", newIP, foundHWaddr)
if foundHWaddr != nil && len(foundHWaddr) != 0 {
// if !bytes.Equal(foundHWaddr, hwaddr) {
// log.Tracef("SHOULD NOT HAPPEN: hwaddr in IP pool %s is not equal to hwaddr in lease %s", foundHWaddr, hwaddr)
// }
log.Tracef("will try again")
continue
}
foundIP = newIP
@@ -236,7 +300,7 @@ func (s *Server) findFreeIP(hwaddr net.HardwareAddr) (net.IP, error) {
return foundIP, nil
}
func (s *Server) getIPpool(ip net.IP) net.HardwareAddr {
func (s *Server) findReservedHWaddr(ip net.IP) net.HardwareAddr {
rawIP := []byte(ip)
IP4 := [4]byte{rawIP[0], rawIP[1], rawIP[2], rawIP[3]}
return s.IPpool[IP4]
@@ -256,133 +320,230 @@ func (s *Server) unreserveIP(ip net.IP) {
// ServeDHCP handles an incoming DHCP request
func (s *Server) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dhcp4.Options) dhcp4.Packet {
log.Tracef("Got %v message", msgType)
log.Tracef("Leases:")
for i, lease := range s.leases {
log.Tracef("Lease #%d: hwaddr %s, ip %s, expiry %s", i, lease.HWAddr, lease.IP, lease.Expiry)
}
log.Tracef("IP pool:")
for ip, hwaddr := range s.IPpool {
log.Tracef("IP pool entry %s -> %s", net.IPv4(ip[0], ip[1], ip[2], ip[3]), hwaddr)
}
s.printLeases()
switch msgType {
case dhcp4.Discover: // Broadcast Packet From Client - Can I have an IP?
// find a lease, but don't update lease time
log.Tracef("Got from client: Discover")
lease, err := s.reserveLease(p)
if err != nil {
log.Tracef("Couldn't find free lease: %s", err)
// couldn't find lease, don't respond
return nil
}
reply := dhcp4.ReplyPacket(p, dhcp4.Offer, s.ipnet.IP, lease.IP, s.leaseTime, s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList]))
log.Tracef("Replying with offer: offered IP %v for %v with options %+v", lease.IP, s.leaseTime, reply.ParseOptions())
return reply
return s.handleDiscover(p, options)
case dhcp4.Request: // Broadcast From Client - I'll take that IP (Also start for renewals)
// start/renew a lease -- update lease time
// some clients (OSX) just go right ahead and do Request first from previously known IP, if they get NAK, they restart full cycle with Discover then Request
return s.handleDHCP4Request(p, options)
case dhcp4.Decline: // Broadcast From Client - Sorry I can't use that IP
log.Tracef("Got from client: Decline")
return s.handleDecline(p, options)
case dhcp4.Release: // From Client, I don't need that IP anymore
log.Tracef("Got from client: Release")
return s.handleRelease(p, options)
case dhcp4.Inform: // From Client, I have this IP and there's nothing you can do about it
log.Tracef("Got from client: Inform")
// do nothing
return s.handleInform(p, options)
// from server -- ignore those but enumerate just in case
case dhcp4.Offer: // Broadcast From Server - Here's an IP
log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: Offer")
log.Printf("DHCP: received message from %s: Offer", p.CHAddr())
case dhcp4.ACK: // From Server, Yes you can have that IP
log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: ACK")
log.Printf("DHCP: received message from %s: ACK", p.CHAddr())
case dhcp4.NAK: // From Server, No you cannot have that IP
log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: NAK")
log.Printf("DHCP: received message from %s: NAK", p.CHAddr())
default:
log.Printf("Unknown DHCP packet detected, ignoring: %v", msgType)
log.Printf("DHCP: unknown packet %v from %s", msgType, p.CHAddr())
return nil
}
return nil
}
// Send ICMP to the specified machine
// Return TRUE if it doesn't reply, which probably means that the IP is available
func (s *Server) addrAvailable(target net.IP) bool {
if s.ICMPTimeout == 0 {
return true
}
pinger, err := ping.NewPinger(target.String())
if err != nil {
log.Error("ping.NewPinger(): %v", err)
return true
}
pinger.SetPrivileged(true)
pinger.Timeout = time.Duration(s.ICMPTimeout) * time.Millisecond
pinger.Count = 1
reply := false
pinger.OnRecv = func(pkt *ping.Packet) {
// log.Tracef("Received ICMP Reply from %v", target)
reply = true
}
log.Tracef("Sending ICMP Echo to %v", target)
pinger.Run()
if reply {
log.Info("DHCP: IP conflict: %v is already used by another device", target)
return false
}
log.Tracef("ICMP procedure is complete: %v", target)
return true
}
// Add the specified IP to the black list for a time period
func (s *Server) blacklistLease(lease *Lease) {
hw := make(net.HardwareAddr, 6)
s.reserveIP(lease.IP, hw)
s.Lock()
lease.HWAddr = hw
lease.Hostname = ""
lease.Expiry = time.Now().Add(s.leaseTime)
s.Unlock()
}
// Return TRUE if DHCP packet is correct
func isValidPacket(p dhcp4.Packet) bool {
hw := p.CHAddr()
zeroes := make([]byte, len(hw))
if bytes.Equal(hw, zeroes) {
log.Tracef("Packet has empty CHAddr")
return false
}
return true
}
func (s *Server) handleDiscover(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet {
// find a lease, but don't update lease time
var lease *Lease
var err error
reqIP := net.IP(options[dhcp4.OptionRequestedIPAddress])
hostname := p.ParseOptions()[dhcp4.OptionHostName]
log.Tracef("Message from client: Discover. ReqIP: %s HW: %s Hostname: %s",
reqIP, p.CHAddr(), hostname)
if !isValidPacket(p) {
return nil
}
lease = s.findLease(p)
for lease == nil {
lease, err = s.reserveLease(p)
if err != nil {
log.Error("Couldn't find free lease: %s", err)
return nil
}
if !s.addrAvailable(lease.IP) {
s.blacklistLease(lease)
lease = nil
continue
}
break
}
opt := s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList])
reply := dhcp4.ReplyPacket(p, dhcp4.Offer, s.ipnet.IP, lease.IP, s.leaseTime, opt)
log.Tracef("Replying with offer: offered IP %v for %v with options %+v", lease.IP, s.leaseTime, reply.ParseOptions())
return reply
}
func (s *Server) handleDHCP4Request(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet {
log.Tracef("Got from client: Request")
if server, ok := options[dhcp4.OptionServerIdentifier]; ok && !net.IP(server).Equal(s.ipnet.IP) {
var lease *Lease
reqIP := net.IP(options[dhcp4.OptionRequestedIPAddress])
log.Tracef("Message from client: Request. IP: %s ReqIP: %s HW: %s",
p.CIAddr(), reqIP, p.CHAddr())
if !isValidPacket(p) {
return nil
}
server := options[dhcp4.OptionServerIdentifier]
if server != nil && !net.IP(server).Equal(s.ipnet.IP) {
log.Tracef("Request message not for this DHCP server (%v vs %v)", server, s.ipnet.IP)
return nil // Message not for this dhcp server
}
reqIP := net.IP(options[dhcp4.OptionRequestedIPAddress])
if reqIP == nil {
reqIP = p.CIAddr()
}
if reqIP.To4() == nil {
log.Tracef("Replying with NAK: request IP isn't valid IPv4: %s", reqIP)
} else if reqIP == nil || reqIP.To4() == nil {
log.Tracef("Requested IP isn't a valid IPv4: %s", reqIP)
return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
}
if reqIP.Equal(net.IPv4zero) {
log.Tracef("Replying with NAK: request IP is 0.0.0.0")
lease = s.findLease(p)
if lease == nil {
log.Tracef("Lease for %s isn't found", p.CHAddr())
return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
}
log.Tracef("requested IP is %s", reqIP)
lease, err := s.reserveLease(p)
if err != nil {
log.Tracef("Couldn't find free lease: %s", err)
// couldn't find lease, don't respond
return nil
if !lease.IP.Equal(reqIP) {
log.Tracef("Lease for %s doesn't match requested/client IP: %s vs %s",
lease.HWAddr, lease.IP, reqIP)
return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
}
if lease.IP.Equal(reqIP) {
// IP matches lease IP, nothing else to do
lease.Expiry = time.Now().Add(s.leaseTime)
log.Tracef("Replying with ACK: request IP matches lease IP, nothing else to do. IP %v for %v", lease.IP, p.CHAddr())
return dhcp4.ReplyPacket(p, dhcp4.ACK, s.ipnet.IP, lease.IP, s.leaseTime, s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList]))
}
lease.Expiry = time.Now().Add(s.leaseTime)
log.Tracef("Replying with ACK. IP: %s HW: %s Expire: %s",
lease.IP, lease.HWAddr, lease.Expiry)
opt := s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList])
return dhcp4.ReplyPacket(p, dhcp4.ACK, s.ipnet.IP, lease.IP, s.leaseTime, opt)
}
//
// requested IP different from lease
//
func (s *Server) handleInform(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet {
log.Tracef("Message from client: Inform. IP: %s HW: %s",
p.CIAddr(), p.CHAddr())
log.Tracef("lease IP is different from requested IP: %s vs %s", lease.IP, reqIP)
return nil
}
hwaddr := s.getIPpool(reqIP)
if hwaddr == nil {
// not in pool, check if it's in DHCP range
if dhcp4.IPInRange(s.leaseStart, s.leaseStop, reqIP) {
// okay, we can give it to our client -- it's in our DHCP range and not taken, so let them use their IP
log.Tracef("Replying with ACK: request IP %v is not taken, so assigning lease IP %v to it, for %v", reqIP, lease.IP, p.CHAddr())
s.unreserveIP(lease.IP)
lease.IP = reqIP
s.reserveIP(reqIP, p.CHAddr())
lease.Expiry = time.Now().Add(s.leaseTime)
return dhcp4.ReplyPacket(p, dhcp4.ACK, s.ipnet.IP, lease.IP, s.leaseTime, s.leaseOptions.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList]))
func (s *Server) handleRelease(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet {
log.Tracef("Message from client: Release. IP: %s HW: %s",
p.CIAddr(), p.CHAddr())
return nil
}
func (s *Server) handleDecline(p dhcp4.Packet, options dhcp4.Options) dhcp4.Packet {
reqIP := net.IP(options[dhcp4.OptionRequestedIPAddress])
log.Tracef("Message from client: Decline. IP: %s HW: %s",
reqIP, p.CHAddr())
return nil
}
// Leases returns the list of current DHCP leases (thread-safe)
func (s *Server) Leases() []Lease {
var result []Lease
now := time.Now().Unix()
s.RLock()
for _, lease := range s.leases {
if lease.Expiry.Unix() > now {
result = append(result, *lease)
}
}
if hwaddr != nil && !bytes.Equal(hwaddr, lease.HWAddr) {
log.Printf("SHOULD NOT HAPPEN: IP pool hwaddr does not match lease hwaddr: %s vs %s", hwaddr, lease.HWAddr)
}
// requsted IP is not sufficient, reply with NAK
if hwaddr != nil {
log.Tracef("Replying with NAK: request IP %s is taken, asked by %v", reqIP, p.CHAddr())
return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
}
// requested IP is outside of DHCP range
log.Tracef("Replying with NAK: request IP %s is outside of DHCP range [%s, %s], asked by %v", reqIP, s.leaseStart, s.leaseStop, p.CHAddr())
return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
}
// Leases returns the list of current DHCP leases
func (s *Server) Leases() []*Lease {
s.RLock()
result := s.leases
s.RUnlock()
return result
}
// Print information about the current leases
func (s *Server) printLeases() {
log.Tracef("Leases:")
for i, lease := range s.leases {
log.Tracef("Lease #%d: hwaddr %s, ip %s, expiry %s",
i, lease.HWAddr, lease.IP, lease.Expiry)
}
}
// Reset internal state
func (s *Server) reset() {
s.Lock()
s.leases = nil
s.Unlock()
s.IPpool = make(map[[4]byte]net.HardwareAddr)
}