From 8b4a1ca71361c14f19dd1fbd8549235d9df0a2bb Mon Sep 17 00:00:00 2001
From: Eugene Bujak <hmage@hmage.net>
Date: Fri, 28 Dec 2018 17:17:51 +0300
Subject: [PATCH] First implementation of DHCP server, compiles but not tested
yet.
---
config.go | 48 +----
dhcp.go | 36 +++-
dhcpd/check_other_dhcp.go | 143 ++++++++++++++
dhcpd/dhcpd.go | 389 ++++++++++++++++++++++++++++++++++++++
dhcpd/filter_conn.go | 62 ++++++
dhcpd/helpers.go | 101 ++++++++++
dhcpd/standalone/main.go | 111 +++++++++++
go.mod | 2 +
go.sum | 2 +
9 files changed, 847 insertions(+), 47 deletions(-)
create mode 100644 dhcpd/check_other_dhcp.go
create mode 100644 dhcpd/dhcpd.go
create mode 100644 dhcpd/filter_conn.go
create mode 100644 dhcpd/helpers.go
create mode 100644 dhcpd/standalone/main.go
diff --git a/config.go b/config.go
index 89ec9e20..15ecffc1 100644
--- a/config.go
+++ b/config.go
@@ -6,8 +6,8 @@ import (
"os"
"path/filepath"
"sync"
- "time"
+ "github.com/AdguardTeam/AdGuardHome/dhcpd"
"github.com/AdguardTeam/AdGuardHome/dnsfilter"
"github.com/AdguardTeam/AdGuardHome/dnsforward"
"gopkg.in/yaml.v2"
@@ -24,15 +24,15 @@ type configuration struct {
ourConfigFilename string // Config filename (can be overriden via the command line arguments)
ourBinaryDir string // Location of our directory, used to protect against CWD being somewhere else
- BindHost string `yaml:"bind_host"`
- BindPort int `yaml:"bind_port"`
- AuthName string `yaml:"auth_name"`
- AuthPass string `yaml:"auth_pass"`
- Language string `yaml:"language"` // two-letter ISO 639-1 language code
- DNS dnsConfig `yaml:"dns"`
- Filters []filter `yaml:"filters"`
- UserRules []string `yaml:"user_rules"`
- DHCP dhcpState `yaml:"dhcp"`
+ BindHost string `yaml:"bind_host"`
+ BindPort int `yaml:"bind_port"`
+ AuthName string `yaml:"auth_name"`
+ AuthPass string `yaml:"auth_pass"`
+ Language string `yaml:"language"` // two-letter ISO 639-1 language code
+ DNS dnsConfig `yaml:"dns"`
+ Filters []filter `yaml:"filters"`
+ UserRules []string `yaml:"user_rules"`
+ DHCP dhcpd.ServerConfig `yaml:"dhcp"`
sync.RWMutex `yaml:"-"`
@@ -50,31 +50,6 @@ type dnsConfig struct {
var defaultDNS = []string{"tls://1.1.1.1", "tls://1.0.0.1"}
-// field ordering is important -- yaml fields will mirror ordering from here
-type dhcpState struct {
- Config dhcpConfig
- Leases []dhcpLease
-}
-
-// field ordering is important -- yaml fields will mirror ordering from here
-type dhcpConfig struct {
- Enabled bool `json:"enabled" yaml:"enabled"`
- InterfaceName string `json:"interface_name" yaml:"interface_name"` // eth0, en0 and so on
- GatewayIP string `json:"gateway_ip" yaml:"gateway_ip"`
- SubnetMask string `json:"subnet_mask" yaml:"subnet_mask"`
- RangeStart string `json:"range_start" yaml:"range_start"`
- RangeEnd string `json:"range_end" yaml:"range_end"`
- LeaseDuration uint64 `json:"lease_duration" yaml:"lease_duration"` // in seconds
-}
-
-// field ordering is important -- yaml fields will mirror ordering from here
-type dhcpLease struct {
- HWAddr [6]byte `json:"mac" yaml:"hwaddr"`
- IP string `json:"ip"` // json by default keeps IP uppercase but we need lowercase
- Hostname string
- Expires time.Time
-}
-
// initialize to default values, will be changed later when reading config or parsing command line
var config = configuration{
ourConfigFilename: "AdGuardHome.yaml",
@@ -99,9 +74,6 @@ var config = configuration{
{Filter: dnsfilter.Filter{ID: 3}, Enabled: false, URL: "https://hosts-file.net/ad_servers.txt", Name: "hpHosts - Ad and Tracking servers only"},
{Filter: dnsfilter.Filter{ID: 4}, Enabled: false, URL: "http://www.malwaredomainlist.com/hostslist/hosts.txt", Name: "MalwareDomainList.com Hosts List"},
},
- DHCP: dhcpState{Config: dhcpConfig{
- LeaseDuration: 12 * 60 * 60, // in seconds
- }},
SchemaVersion: currentSchemaVersion,
}
diff --git a/dhcp.go b/dhcp.go
index eb30ab75..b86fa29c 100644
--- a/dhcp.go
+++ b/dhcp.go
@@ -2,15 +2,18 @@ package main
import (
"encoding/json"
- "math/rand"
"net"
"net/http"
+
+ "github.com/AdguardTeam/AdGuardHome/dhcpd"
)
+var dhcpServer = dhcpd.Server{}
+
func handleDHCPStatus(w http.ResponseWriter, r *http.Request) {
status := map[string]interface{}{
- "config": config.DHCP.Config,
- "leases": config.DHCP.Leases,
+ "config": config.DHCP,
+ "leases": dhcpServer.Leases(),
}
w.Header().Set("Content-Type", "application/json")
@@ -22,14 +25,24 @@ func handleDHCPStatus(w http.ResponseWriter, r *http.Request) {
}
func handleDHCPSetConfig(w http.ResponseWriter, r *http.Request) {
- newconfig := dhcpConfig{}
+ newconfig := dhcpd.ServerConfig{}
err := json.NewDecoder(r.Body).Decode(&newconfig)
if err != nil {
httpError(w, http.StatusBadRequest, "Failed to parse new DHCP config json: %s", err)
return
}
- config.DHCP.Config = newconfig
+ if newconfig.Enabled {
+ err := dhcpServer.Start(&newconfig)
+ if err != nil {
+ httpError(w, http.StatusBadRequest, "Failed to start DHCP server: %s", err)
+ return
+ }
+ }
+ if !newconfig.Enabled {
+ dhcpServer.Stop()
+ }
+ config.DHCP = newconfig
}
func handleDHCPInterfaces(w http.ResponseWriter, r *http.Request) {
@@ -93,13 +106,18 @@ func handleDHCPInterfaces(w http.ResponseWriter, r *http.Request) {
}
}
-// TODO: implement
+// implement
func handleDHCPFindActiveServer(w http.ResponseWriter, r *http.Request) {
- found := map[string]bool{
- "found": rand.Intn(2) == 1,
+ found, err := dhcpd.CheckIfOtherDHCPServersPresent(config.DHCP.InterfaceName)
+ result := map[string]interface{}{
+ "found": found,
+ }
+ if err != nil {
+ result["found"] = false
+ result["error"] = err
}
w.Header().Set("Content-Type", "application/json")
- err := json.NewEncoder(w).Encode(found)
+ err = json.NewEncoder(w).Encode(result)
if err != nil {
httpError(w, http.StatusInternalServerError, "Failed to marshal DHCP found json: %s", err)
return
diff --git a/dhcpd/check_other_dhcp.go b/dhcpd/check_other_dhcp.go
new file mode 100644
index 00000000..7aed85ce
--- /dev/null
+++ b/dhcpd/check_other_dhcp.go
@@ -0,0 +1,143 @@
+package dhcpd
+
+import (
+ "crypto/rand"
+ "encoding/binary"
+ "fmt"
+ "math"
+ "net"
+ "os"
+ "time"
+
+ "github.com/krolaw/dhcp4"
+)
+
+func CheckIfOtherDHCPServersPresent(ifaceName string) (bool, error) {
+ iface, err := net.InterfaceByName(ifaceName)
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't find interface by name %s", ifaceName)
+ }
+
+ // get ipv4 address of an interface
+ ifaceIPNet := getIfaceIPv4(iface)
+ if ifaceIPNet == nil {
+ return false, fmt.Errorf("Couldn't find IPv4 address of interface %s %+v", ifaceName, iface)
+ }
+
+ srcIP := ifaceIPNet.IP
+ src := net.JoinHostPort(srcIP.String(), "68")
+ dst := "255.255.255.255:67"
+
+ // form a DHCP request packet, try to emulate existing client as much as possible
+ xId := make([]byte, 8)
+ n, err := rand.Read(xId)
+ if n != 8 && err == nil {
+ err = fmt.Errorf("Generated less than 8 bytes")
+ }
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't generate 8 random bytes")
+ }
+ hostname, err := os.Hostname()
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't get hostname")
+ }
+ requestList := []byte{
+ byte(dhcp4.OptionSubnetMask),
+ byte(dhcp4.OptionClasslessRouteFormat),
+ byte(dhcp4.OptionRouter),
+ byte(dhcp4.OptionDomainNameServer),
+ byte(dhcp4.OptionDomainName),
+ byte(dhcp4.OptionDomainSearch),
+ 252, // private/proxy autodiscovery
+ 95, // LDAP
+ byte(dhcp4.OptionNetBIOSOverTCPIPNameServer),
+ byte(dhcp4.OptionNetBIOSOverTCPIPNodeType),
+ }
+ maxUDPsizeRaw := make([]byte, 2)
+ binary.BigEndian.PutUint16(maxUDPsizeRaw, 1500)
+ leaseTimeRaw := make([]byte, 4)
+ leaseTime := uint32(math.RoundToEven(time.Duration(time.Hour * 24 * 90).Seconds()))
+ binary.BigEndian.PutUint32(leaseTimeRaw, leaseTime)
+ options := []dhcp4.Option{
+ {dhcp4.OptionParameterRequestList, requestList},
+ {dhcp4.OptionMaximumDHCPMessageSize, maxUDPsizeRaw},
+ {dhcp4.OptionClientIdentifier, append([]byte{0x01}, iface.HardwareAddr...)},
+ {dhcp4.OptionIPAddressLeaseTime, leaseTimeRaw},
+ {dhcp4.OptionHostName, []byte(hostname)},
+ }
+ packet := dhcp4.RequestPacket(dhcp4.Discover, iface.HardwareAddr, nil, xId, false, options)
+
+ // resolve 0.0.0.0:68
+ udpAddr, err := net.ResolveUDPAddr("udp4", src)
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't resolve UDP address %s", src)
+ }
+ // spew.Dump(udpAddr, err)
+
+ if !udpAddr.IP.To4().Equal(srcIP) {
+ return false, wrapErrPrint(err, "Resolved UDP address is not %s", src)
+ }
+
+ // resolve 255.255.255.255:67
+ dstAddr, err := net.ResolveUDPAddr("udp4", dst)
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't resolve UDP address %s", dst)
+ }
+
+ // bind to 0.0.0.0:68
+ trace("Listening to udp4 %+v", udpAddr)
+ c, err := net.ListenPacket("udp4", src)
+ if c != nil {
+ defer c.Close()
+ }
+ // spew.Dump(c, err)
+ // spew.Printf("net.ListenUDP returned %v, %v\n", c, err)
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't listen to %s", src)
+ }
+
+ // send to 255.255.255.255:67
+ n, err = c.WriteTo(packet, dstAddr)
+ // spew.Dump(n, err)
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't send a packet to %s", dst)
+ }
+
+ // wait for answer
+ trace("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
+ return false, nil
+ }
+ if err != nil {
+ return false, wrapErrPrint(err, "Couldn't receive packet")
+ }
+ if n > 0 {
+ b = b[:n]
+ }
+ // spew.Dump(n, fromAddr, err, b)
+
+ if n < 240 {
+ // packet too small for dhcp
+ return false, wrapErrPrint(err, "got packet that's too small for DHCP")
+ }
+
+ response := dhcp4.Packet(b[:n])
+ if response.HLen() > 16 {
+ // invalid size
+ return false, wrapErrPrint(err, "got malformed packet with HLen() > 16")
+ }
+
+ parsedOptions := response.ParseOptions()
+ _, ok := parsedOptions[dhcp4.OptionDHCPMessageType]
+ if !ok {
+ return false, wrapErrPrint(err, "got malformed packet without DHCP message type")
+ }
+
+ // that's a DHCP server there
+ return true, nil
+}
diff --git a/dhcpd/dhcpd.go b/dhcpd/dhcpd.go
new file mode 100644
index 00000000..8dc500a1
--- /dev/null
+++ b/dhcpd/dhcpd.go
@@ -0,0 +1,389 @@
+package dhcpd
+
+import (
+ "bytes"
+ "fmt"
+ "log"
+ "net"
+ "time"
+
+ "github.com/krolaw/dhcp4"
+)
+
+const defaultDiscoverTime = time.Second * 3
+
+// field ordering is important -- yaml fields will mirror ordering from here
+type Lease struct {
+ hwaddr net.HardwareAddr `json:"mac" yaml:"hwaddr"`
+ ip net.IP `json:"ip"`
+ expiry time.Time `json:"expires"`
+}
+
+// field ordering is important -- yaml fields will mirror ordering from here
+type ServerConfig struct {
+ Enabled bool `json:"enabled" yaml:"enabled"`
+ InterfaceName string `json:"interface_name" yaml:"interface_name"` // eth0, en0 and so on
+ GatewayIP string `json:"gateway_ip" yaml:"gateway_ip"`
+ SubnetMask string `json:"subnet_mask" yaml:"subnet_mask"`
+ 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
+}
+
+type Server struct {
+ conn *filterConn // listening UDP socket
+
+ ipnet *net.IPNet // if interface name changes, this needs to be reset
+
+ // leases
+ leases []*Lease
+ leaseStart net.IP // parsed from config RangeStart
+ leaseStop net.IP // parsed from config RangeEnd
+ leaseTime time.Duration // parsed from config LeaseDuration
+ leaseOptions dhcp4.Options // parsed from config GatewayIP and SubnetMask
+
+ // IP address pool -- if entry is in the pool, then it's attached to a lease
+ IPpool map[[4]byte]net.HardwareAddr
+
+ ServerConfig
+}
+
+// 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 {
+ if config != nil {
+ s.ServerConfig = *config
+ }
+
+ iface, err := net.InterfaceByName(s.InterfaceName)
+ if err != nil {
+ s.closeConn() // in case it was already started
+ return wrapErrPrint(err, "Couldn't find interface by name %s", s.InterfaceName)
+ }
+
+ // get ipv4 address of an interface
+ s.ipnet = getIfaceIPv4(iface)
+ if s.ipnet == nil {
+ s.closeConn() // in case it was already started
+ return wrapErrPrint(err, "Couldn't find IPv4 address of interface %s %+v", s.InterfaceName, iface)
+ }
+
+ if s.LeaseDuration == 0 {
+ s.leaseTime = time.Hour * 2
+ s.LeaseDuration = uint(s.leaseTime.Seconds())
+ } else {
+ s.leaseTime = time.Second * time.Duration(s.LeaseDuration)
+ }
+
+ s.leaseStart, err = parseIPv4(s.RangeStart)
+ if err != nil {
+ s.closeConn() // in case it was already started
+ return wrapErrPrint(err, "Failed to parse range start address %s", s.RangeStart)
+ }
+
+ s.leaseStop, err = parseIPv4(s.RangeEnd)
+ if err != nil {
+ s.closeConn() // in case it was already started
+ return wrapErrPrint(err, "Failed to parse range end address %s", s.RangeEnd)
+ }
+
+ subnet, err := parseIPv4(s.SubnetMask)
+ if err != nil {
+ s.closeConn() // in case it was already started
+ return wrapErrPrint(err, "Failed to parse subnet mask %s", s.SubnetMask)
+ }
+
+ // if !bytes.Equal(subnet, s.ipnet.Mask) {
+ // s.closeConn() // in case it was already started
+ // return wrapErrPrint(err, "specified subnet mask %s does not meatch interface %s subnet mask %s", s.SubnetMask, s.InterfaceName, s.ipnet.Mask)
+ // }
+
+ router, err := parseIPv4(s.GatewayIP)
+ if err != nil {
+ s.closeConn() // in case it was already started
+ return wrapErrPrint(err, "Failed to parse gateway IP %s", s.GatewayIP)
+ }
+
+ s.leaseOptions = dhcp4.Options{
+ dhcp4.OptionSubnetMask: subnet,
+ dhcp4.OptionRouter: router,
+ dhcp4.OptionDomainNameServer: s.ipnet.IP,
+ }
+
+ // TODO: don't close if interface and addresses are the same
+ if s.conn != nil {
+ s.closeConn()
+ }
+
+ 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")
+ }
+
+ s.conn = c
+
+ go func() {
+ // operate on c instead of c.conn because c.conn can change over time
+ err := dhcp4.Serve(c, s)
+ if err != nil {
+ log.Printf("dhcp4.Serve() returned with error: %s", err)
+ }
+ c.Close() // in case Serve() exits for other reason than listening socket closure
+ }()
+
+ return nil
+}
+
+func (s *Server) Stop() error {
+ if s.conn == nil {
+ // nothing to do, return silently
+ return nil
+ }
+ err := s.closeConn()
+ if err != nil {
+ return wrapErrPrint(err, "Couldn't close UDP listening socket")
+ }
+
+ return nil
+}
+
+// closeConn will close the connection and set it to zero
+func (s *Server) closeConn() error {
+ if s.conn == nil {
+ return nil
+ }
+ err := s.conn.Close()
+ s.conn = nil
+ return err
+}
+
+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
+ // since we need to retain it we need to make our own copy
+ hwaddrCOW := p.CHAddr()
+ hwaddr := make(net.HardwareAddr, len(hwaddrCOW))
+ copy(hwaddr, hwaddrCOW)
+ foundLease := s.locateLease(p)
+ if foundLease != nil {
+ // trace("found lease for %s: %+v", hwaddr, foundLease)
+ return foundLease, nil
+ }
+ // not assigned a lease, create new one, find IP from LRU
+ trace("Lease not found for %s: creating new one", hwaddr)
+ ip, err := s.findFreeIP(p, hwaddr)
+ if err != nil {
+ return nil, wrapErrPrint(err, "Couldn't find free IP for the lease %s", hwaddr.String())
+ }
+ trace("Assigning to %s IP address %s", hwaddr, ip.String())
+ lease := &Lease{hwaddr: hwaddr, ip: ip}
+ s.leases = append(s.leases, lease)
+ return lease, nil
+}
+
+func (s *Server) locateLease(p dhcp4.Packet) *Lease {
+ hwaddr := p.CHAddr()
+ for i := range s.leases {
+ if bytes.Equal([]byte(hwaddr), []byte(s.leases[i].hwaddr)) {
+ // trace("bytes.Equal(%s, %s) returned true", hwaddr, s.leases[i].hwaddr)
+ return s.leases[i]
+ }
+ }
+ return nil
+}
+
+func (s *Server) findFreeIP(p dhcp4.Packet, hwaddr net.HardwareAddr) (net.IP, error) {
+ // if IP pool is nil, lazy initialize it
+ if s.IPpool == nil {
+ s.IPpool = make(map[[4]byte]net.HardwareAddr)
+ }
+
+ // go from start to end, find unreserved IP
+ 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)
+ trace("tried IP %v, got hwaddr %v", newIP, foundHWaddr)
+ if foundHWaddr != nil && len(foundHWaddr) != 0 {
+ // if !bytes.Equal(foundHWaddr, hwaddr) {
+ // trace("SHOULD NOT HAPPEN: hwaddr in IP pool %s is not equal to hwaddr in lease %s", foundHWaddr, hwaddr)
+ // }
+ trace("will try again")
+ continue
+ }
+ foundIP = newIP
+ break
+ }
+
+ if foundIP == nil {
+ // TODO: LRU
+ return nil, fmt.Errorf("Couldn't find free entry in IP pool")
+ }
+
+ s.reserveIP(foundIP, hwaddr)
+
+ return foundIP, nil
+}
+
+func (s *Server) getIPpool(ip net.IP) net.HardwareAddr {
+ rawIP := []byte(ip)
+ IP4 := [4]byte{rawIP[0], rawIP[1], rawIP[2], rawIP[3]}
+ return s.IPpool[IP4]
+}
+
+func (s *Server) reserveIP(ip net.IP, hwaddr net.HardwareAddr) {
+ rawIP := []byte(ip)
+ IP4 := [4]byte{rawIP[0], rawIP[1], rawIP[2], rawIP[3]}
+ s.IPpool[IP4] = hwaddr
+}
+
+func (s *Server) unreserveIP(ip net.IP) {
+ rawIP := []byte(ip)
+ IP4 := [4]byte{rawIP[0], rawIP[1], rawIP[2], rawIP[3]}
+ delete(s.IPpool, IP4)
+}
+
+func (s *Server) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dhcp4.Options) dhcp4.Packet {
+ trace("Got %v message", msgType)
+ trace("Leases:")
+ for i, lease := range s.leases {
+ trace("Lease #%d: hwaddr %s, ip %s, expiry %s", i, lease.hwaddr, lease.ip, lease.expiry)
+ }
+ trace("IP pool:")
+ for ip, hwaddr := range s.IPpool {
+ trace("IP pool entry %s -> %s", net.IPv4(ip[0], ip[1], ip[2], ip[3]), hwaddr)
+ }
+ // spew.Dump(s.leases, s.IPpool)
+ // log.Printf("Called with msgType = %v, options = %+v", msgType, options)
+ // spew.Dump(p)
+ // log.Printf("%14s %v", "p.Broadcast", p.Broadcast()) // false
+ // log.Printf("%14s %v", "p.CHAddr", p.CHAddr()) // 2c:f0:a2:f2:31:00
+ // log.Printf("%14s %v", "p.CIAddr", p.CIAddr()) // 0.0.0.0
+ // log.Printf("%14s %v", "p.Cookie", p.Cookie()) // [99 130 83 99]
+ // log.Printf("%14s %v", "p.File", p.File()) // []
+ // log.Printf("%14s %v", "p.Flags", p.Flags()) // [0 0]
+ // log.Printf("%14s %v", "p.GIAddr", p.GIAddr()) // 0.0.0.0
+ // log.Printf("%14s %v", "p.HLen", p.HLen()) // 6
+ // log.Printf("%14s %v", "p.HType", p.HType()) // 1
+ // log.Printf("%14s %v", "p.Hops", p.Hops()) // 0
+ // log.Printf("%14s %v", "p.OpCode", p.OpCode()) // BootRequest
+ // log.Printf("%14s %v", "p.Options", p.Options()) // [53 1 1 55 10 1 121 3 6 15 119 252 95 44 46 57 2 5 220 61 7 1 44 240 162 242 49 0 51 4 0 118 167 0 12 4 119 104 109 100 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
+ // log.Printf("%14s %v", "p.ParseOptions", p.ParseOptions()) // map[OptionParameterRequestList:[1 121 3 6 15 119 252 95 44 46] OptionDHCPMessageType:[1] OptionMaximumDHCPMessageSize:[5 220] OptionClientIdentifier:[1 44 240 162 242 49 0] OptionIPAddressLeaseTime:[0 118 167 0] OptionHostName:[119 104 109 100]]
+ // log.Printf("%14s %v", "p.SIAddr", p.SIAddr()) // 0.0.0.0
+ // log.Printf("%14s %v", "p.SName", p.SName()) // []
+ // log.Printf("%14s %v", "p.Secs", p.Secs()) // [0 8]
+ // log.Printf("%14s %v", "p.XId", p.XId()) // [211 184 20 44]
+ // log.Printf("%14s %v", "p.YIAddr", p.YIAddr()) // 0.0.0.0
+
+ switch msgType {
+ case dhcp4.Discover: // Broadcast Packet From Client - Can I have an IP?
+ // find a lease, but don't update lease time
+ trace("Got from client: Discover")
+ lease, err := s.reserveLease(p)
+ if err != nil {
+ trace("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]))
+ trace("Replying with offer: offered IP %v for %v with options %+v", lease.ip, s.leaseTime, reply.ParseOptions())
+ return reply
+ 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
+ trace("Got from client: Request")
+ if server, ok := options[dhcp4.OptionServerIdentifier]; ok && !net.IP(server).Equal(s.ipnet.IP) {
+ trace("Request message not for this DHCP server (%v vs %v)", p, server, s.ipnet.IP)
+ return nil // Message not for this dhcp server
+ }
+
+ reqIP := net.IP(options[dhcp4.OptionRequestedIPAddress])
+ if reqIP == nil {
+ reqIP = net.IP(p.CIAddr())
+ }
+
+ if reqIP.To4() == nil {
+ trace("Replying with NAK: request IP isn't valid IPv4: %s", reqIP)
+ return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
+ }
+
+ if reqIP.Equal(net.IPv4zero) {
+ trace("Replying with NAK: request IP is 0.0.0.0")
+ return dhcp4.ReplyPacket(p, dhcp4.NAK, s.ipnet.IP, nil, 0, nil)
+ }
+
+ trace("requested IP is %s", reqIP)
+ lease, err := s.reserveLease(p)
+ if err != nil {
+ trace("Couldn't find free lease: %s", err)
+ // couldn't find lease, don't respond
+ return nil
+ }
+
+ if lease.ip.Equal(reqIP) {
+ // IP matches lease IP, nothing else to do
+ lease.expiry = time.Now().Add(s.leaseTime)
+ trace("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]))
+ }
+
+ //
+ // requested IP different from lease
+ //
+
+ trace("lease IP is different from requested IP: %s vs %s", lease.ip, reqIP)
+
+ 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
+ trace("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]))
+ }
+ }
+
+ 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 {
+ trace("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
+ trace("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)
+ case dhcp4.Decline: // Broadcast From Client - Sorry I can't use that IP
+ trace("Got from client: Decline")
+
+ case dhcp4.Release: // From Client, I don't need that IP anymore
+ trace("Got from client: Release")
+
+ case dhcp4.Inform: // From Client, I have this IP and there's nothing you can do about it
+ trace("Got from client: Inform")
+ // do nothing
+
+ // 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")
+ case dhcp4.ACK: // From Server, Yes you can have that IP
+ log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: ACK")
+ case dhcp4.NAK: // From Server, No you cannot have that IP
+ log.Printf("SHOULD NOT HAPPEN -- FROM ANOTHER DHCP SERVER: NAK")
+ default:
+ log.Printf("Unknown DHCP packet detected, ignoring: %v", msgType)
+ return nil
+ }
+ return nil
+}
+
+func (s *Server) Leases() []*Lease {
+ return s.leases
+}
diff --git a/dhcpd/filter_conn.go b/dhcpd/filter_conn.go
new file mode 100644
index 00000000..cd943ab1
--- /dev/null
+++ b/dhcpd/filter_conn.go
@@ -0,0 +1,62 @@
+package dhcpd
+
+import (
+ "net"
+
+ "github.com/joomcode/errorx"
+ "golang.org/x/net/ipv4"
+)
+
+// TODO: on windows, controlmessage does not work, try to find out another way
+// https://github.com/golang/net/blob/master/ipv4/payload.go#L13
+
+type filterConn struct {
+ iface net.Interface
+ conn *ipv4.PacketConn
+ // cm *ipv4.ControlMessage
+}
+
+func newFilterConn(iface net.Interface, address string) (*filterConn, error) {
+ c, err := net.ListenPacket("udp4", address)
+ if err != nil {
+ return nil, errorx.Decorate(err, "Couldn't listen to %s on UDP4", address)
+ }
+
+ p := ipv4.NewPacketConn(c)
+ err = p.SetControlMessage(ipv4.FlagInterface, true)
+ if err != nil {
+ c.Close()
+ return nil, errorx.Decorate(err, "Couldn't set control message FlagInterface on connection")
+ }
+
+ return &filterConn{iface: iface, conn: p}, nil
+}
+
+func (f *filterConn) ReadFrom(b []byte) (int, net.Addr, error) {
+ for { // read until we find a suitable packet
+ n, cm, addr, err := f.conn.ReadFrom(b)
+ if err != nil {
+ return 0, addr, errorx.Decorate(err, "Error when reading from socket")
+ }
+ if cm == nil {
+ // no controlmessage was passed, so pass the packet to the caller
+ return n, addr, nil
+ }
+ if cm.IfIndex == f.iface.Index {
+ return n, addr, nil
+ }
+ // packet doesn't match criteria, drop it
+ }
+ return 0, nil, nil
+}
+
+func (f *filterConn) WriteTo(b []byte, addr net.Addr) (int, error) {
+ cm := ipv4.ControlMessage{
+ IfIndex: f.iface.Index,
+ }
+ return f.conn.WriteTo(b, &cm, addr)
+}
+
+func (f *filterConn) Close() error {
+ return f.conn.Close()
+}
diff --git a/dhcpd/helpers.go b/dhcpd/helpers.go
new file mode 100644
index 00000000..cf721f31
--- /dev/null
+++ b/dhcpd/helpers.go
@@ -0,0 +1,101 @@
+package dhcpd
+
+import (
+ "fmt"
+ "log"
+ "net"
+ "os"
+ "path"
+ "runtime"
+ "strings"
+
+ "github.com/joomcode/errorx"
+)
+
+func trace(format string, args ...interface{}) {
+ pc := make([]uintptr, 10) // at least 1 entry needed
+ runtime.Callers(2, pc)
+ f := runtime.FuncForPC(pc[0])
+ var buf strings.Builder
+ buf.WriteString(fmt.Sprintf("%s(): ", path.Base(f.Name())))
+ text := fmt.Sprintf(format, args...)
+ buf.WriteString(text)
+ if len(text) == 0 || text[len(text)-1] != '\n' {
+ buf.WriteRune('\n')
+ }
+ fmt.Fprint(os.Stderr, buf.String())
+}
+
+func isTimeout(err error) bool {
+ operr, ok := err.(*net.OpError)
+ if !ok {
+ return false
+ }
+ return operr.Timeout()
+}
+
+// return first IPv4 address of an interface, if there is any
+func getIfaceIPv4(iface *net.Interface) *net.IPNet {
+ ifaceAddrs, err := iface.Addrs()
+ if err != nil {
+ panic(err)
+ }
+
+ for _, addr := range ifaceAddrs {
+ ipnet, ok := addr.(*net.IPNet)
+ if !ok {
+ // not an IPNet, should not happen
+ log.Fatalf("SHOULD NOT HAPPEN: got iface.Addrs() element %s that is not net.IPNet", addr)
+ }
+
+ if ipnet.IP.To4() == nil {
+ log.Printf("Got IP that is not IPv4: %v", ipnet.IP)
+ continue
+ }
+
+ log.Printf("Got IP that is IPv4: %v", ipnet.IP)
+ return &net.IPNet{
+ IP: ipnet.IP.To4(),
+ Mask: ipnet.Mask,
+ }
+ }
+ return nil
+}
+
+func isConnClosed(err error) bool {
+ if err == nil {
+ return false
+ }
+ nerr, ok := err.(*net.OpError)
+ if !ok {
+ return false
+ }
+
+ if strings.Contains(nerr.Err.Error(), "use of closed network connection") {
+ return true
+ }
+
+ return false
+}
+
+func wrapErrPrint(err error, message string, args ...interface{}) error {
+ var errx error
+ if err == nil {
+ errx = fmt.Errorf(message, args...)
+ } else {
+ errx = errorx.Decorate(err, message, args...)
+ }
+ log.Println(errx.Error())
+ return errx
+}
+
+func parseIPv4(text string) (net.IP, error) {
+ result := net.ParseIP(text)
+ if result == nil {
+ return nil, fmt.Errorf("%s is not an IP address", text)
+ }
+ if result.To4() == nil {
+ return nil, fmt.Errorf("%s is not an IPv4 address", text)
+ }
+ return result.To4(), nil
+}
diff --git a/dhcpd/standalone/main.go b/dhcpd/standalone/main.go
new file mode 100644
index 00000000..f6dac3ac
--- /dev/null
+++ b/dhcpd/standalone/main.go
@@ -0,0 +1,111 @@
+package main
+
+import (
+ "log"
+ "net"
+ "os"
+ "os/signal"
+ "syscall"
+ "time"
+
+ "github.com/AdguardTeam/AdGuardHome/dhcpd"
+ "github.com/krolaw/dhcp4"
+)
+
+func main() {
+ if len(os.Args) < 2 {
+ log.Printf("Usage: %s <interface name>", os.Args[0])
+ os.Exit(64)
+ }
+
+ ifaceName := os.Args[1]
+ present, err := dhcpd.CheckIfOtherDHCPServersPresent(ifaceName)
+ if err != nil {
+ panic(err)
+ }
+ log.Printf("Found DHCP server? %v", present)
+ if present {
+ log.Printf("Will not start DHCP server because there's already running one on the network")
+ os.Exit(1)
+ }
+
+ iface, err := net.InterfaceByName(ifaceName)
+ if err != nil {
+ panic(err)
+ }
+
+ // get ipv4 address of an interface
+ ifaceIPNet := getIfaceIPv4(iface)
+ if ifaceIPNet == nil {
+ panic(err)
+ }
+
+ // append 10 to server's IP address as start
+ start := dhcp4.IPAdd(ifaceIPNet.IP, 10)
+ // lease range is 100 IP's, but TODO: don't go beyond end of subnet mask
+ stop := dhcp4.IPAdd(start, 100)
+
+ server := dhcpd.Server{}
+ config := dhcpd.ServerConfig{
+ InterfaceName: ifaceName,
+ RangeStart: start.String(),
+ RangeEnd: stop.String(),
+ SubnetMask: "255.255.255.0",
+ GatewayIP: "192.168.7.1",
+ }
+ log.Printf("Starting DHCP server")
+ err = server.Start(&config)
+ if err != nil {
+ panic(err)
+ }
+
+ time.Sleep(time.Second)
+ log.Printf("Stopping DHCP server")
+ err = server.Stop()
+ if err != nil {
+ panic(err)
+ }
+ log.Printf("Starting DHCP server")
+ err = server.Start(&config)
+ if err != nil {
+ panic(err)
+ }
+ log.Printf("Starting DHCP server while it's already running")
+ err = server.Start(&config)
+ if err != nil {
+ panic(err)
+ }
+ log.Printf("Now serving DHCP")
+ signal_channel := make(chan os.Signal)
+ signal.Notify(signal_channel, syscall.SIGINT, syscall.SIGTERM)
+ <-signal_channel
+
+}
+
+// return first IPv4 address of an interface, if there is any
+func getIfaceIPv4(iface *net.Interface) *net.IPNet {
+ ifaceAddrs, err := iface.Addrs()
+ if err != nil {
+ panic(err)
+ }
+
+ for _, addr := range ifaceAddrs {
+ ipnet, ok := addr.(*net.IPNet)
+ if !ok {
+ // not an IPNet, should not happen
+ log.Fatalf("SHOULD NOT HAPPEN: got iface.Addrs() element %s that is not net.IPNet", addr)
+ }
+
+ if ipnet.IP.To4() == nil {
+ log.Printf("Got IP that is not IPv4: %v", ipnet.IP)
+ continue
+ }
+
+ log.Printf("Got IP that is IPv4: %v", ipnet.IP)
+ return &net.IPNet{
+ IP: ipnet.IP.To4(),
+ Mask: ipnet.Mask,
+ }
+ }
+ return nil
+}
diff --git a/go.mod b/go.mod
index 36ddb6a2..bdc4c0d3 100644
--- a/go.mod
+++ b/go.mod
@@ -6,11 +6,13 @@ require (
github.com/ameshkov/dnscrypt v1.0.1
github.com/beefsack/go-rate v0.0.0-20180408011153-efa7637bb9b6
github.com/bluele/gcache v0.0.0-20171010155617-472614239ac7
+ github.com/davecgh/go-spew v1.1.1
github.com/go-ole/go-ole v1.2.1 // indirect
github.com/go-test/deep v1.0.1
github.com/gobuffalo/packr v1.19.0
github.com/jedisct1/go-dnsstamps v0.0.0-20180418170050-1e4999280f86
github.com/joomcode/errorx v0.1.0
+ github.com/krolaw/dhcp4 v0.0.0-20180925202202-7cead472c414
github.com/miekg/dns v1.1.1
github.com/patrickmn/go-cache v2.1.0+incompatible
github.com/pkg/errors v0.8.0
diff --git a/go.sum b/go.sum
index 1a32fbbb..4c18efc7 100644
--- a/go.sum
+++ b/go.sum
@@ -45,6 +45,8 @@ github.com/joomcode/errorx v0.1.0 h1:QmJMiI1DE1UFje2aI1ZWO/VMT5a32qBoXUclGOt8vsc
github.com/joomcode/errorx v0.1.0/go.mod h1:kgco15ekB6cs+4Xjzo7SPeXzx38PbJzBwbnu9qfVNHQ=
github.com/konsorten/go-windows-terminal-sequences v1.0.1 h1:mweAR1A6xJ3oS2pRaGiHgQ4OO8tzTaLawm8vnODuwDk=
github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/krolaw/dhcp4 v0.0.0-20180925202202-7cead472c414 h1:6wnYc2S/lVM7BvR32BM74ph7bPgqMztWopMYKgVyEho=
+github.com/krolaw/dhcp4 v0.0.0-20180925202202-7cead472c414/go.mod h1:0AqAH3ZogsCrvrtUpvc6EtVKbc3w6xwZhkvGLuqyi3o=
github.com/markbates/oncer v0.0.0-20181014194634-05fccaae8fc4 h1:Mlji5gkcpzkqTROyE4ZxZ8hN7osunMb2RuGVrbvMvCc=
github.com/markbates/oncer v0.0.0-20181014194634-05fccaae8fc4/go.mod h1:Ld9puTsIW75CHf65OeIOkyKbteujpZVXDpWK6YGZbxE=
github.com/miekg/dns v1.1.1 h1:DVkblRdiScEnEr0LR9nTnEQqHYycjkXW9bOjd+2EL2o=