8000 support netmask/gateway for file plugin by skoef · Pull Request #147 · coredhcp/coredhcp · GitHub
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support netmask/gateway for file plugin #147

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support netmask/gateway for file plugin #147

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10 changes: 10 additions & 0 deletions cmds/coredhcp/config.yml.example
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Original file line number Diff line number Diff line change
Expand Up @@ -137,6 +137,16 @@ server4:
# The IP address should be one address where this server is reachable
- server_id: 10.10.10.1

# file serves leases defined in a static file, matching link-layer addresses to IPs
# - file: <file name> [autorefresh]
# The file format is one lease per line, "<hw address> <IPv4> [netmask [gateway]]"
# where the netmask and gateway are optional. These are particularly useful
# when not all static leases are from the same subnet and have different
# routers and netmasks.
# When the 'autorefresh' argument is given, the plugin will try to refresh
# the lease mapping during runtime whenever the lease file is updated.
- file: "leases.txt"

# dns advertises DNS resolvers usable by the clients on this network
# - dns: <IP address> <...IP addresses>
- dns: 8.8.8.8 8.8.4.4
Expand Down
132 changes: 64 additions & 68 deletions plugins/file/plugin.go
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8000
Original file line number Diff line number Diff line change
Expand Up @@ -4,11 +4,13 @@

// Package file enables static mapping of MAC <--> IP addresses.
// The mapping is stored in a text file, where each mapping is described by one line containing
// two fields separated by spaces: MAC address, and IP address. For example:
// at least two fields separated by spaces: MAC address, and IP address. IPv4 addresses
// can be followed by netmask and gateway address. For example:
//
// $ cat file_leases.txt
// 00:11:22:33:44:55 10.0.0.1
// 01:23:45:67:89:01 10.0.10.10
// 00:11:22:33:44:56 10.1.0.1 255.255.255.128 10.1.0.10
// 01:23:45:67:89:01 2001:db8::10:2
//
// To specify the plugin configuration in the server6/server4 sections of the config file, just
// pass the leases file name as plugin argument, e.g.:
Expand Down Expand Up @@ -40,6 +42,7 @@ import (
"github.com/coredhcp/coredhcp/handler"
"github.com/coredhcp/coredhcp/logger"
"github.com/coredhcp/coredhcp/plugins"
"github.com/coredhcp/coredhcp/plugins/netmask"
"github.com/fsnotify/fsnotify"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/insomniacslk/dhcp/dhcpv6"
Expand All @@ -58,86 +61,78 @@ var Plugin = plugins.Plugin{
Setup4: setup4,
}

// StaticRecord represents the data for a single static DHCP lease
type StaticRecord struct {
Address net.IP // IPv4 or IPv6 address
Netmask net.IPMask // for IPv4 records
Gateway net.IP // for IPv4 records
}

var recLock sync.RWMutex

// StaticRecords holds a MAC -> IP address mapping
var StaticRecords map[string]net.IP
// StaticRecords holds a MAC -> DHCP lease mapping
var StaticRecords map[string]StaticRecord

// DHCPv6Records and DHCPv4Records are mappings between MAC addresses in
// form of a string, to network configurations.
var (
DHCPv6Records map[string]net.IP
DHCPv4Records map[string]net.IP
)

// LoadDHCPv4Records loads the DHCPv4Records global map with records stored on
// the specified file. The records have to be one per line, a mac address and an
// IPv4 address.
func LoadDHCPv4Records(filename string) (map[string]net.IP, error) {
// loadDHCPRecords parses records stored on the specified file and returns a map
// of MAC address -> IPv4 or IPv6 leases. The records have to be one per line,
// a MAC address and an IPv4 or IPv6 address. For IPv4 records, an additional
// netmask and gateway address can be given as well.
func loadDHCPRecords(v6 bool, filename string) (map[string]StaticRecord, error) {
log.Infof("reading leases from %s", filename)
data, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
records := make(map[string]net.IP)
records := make(map[string]StaticRecord)
for _, lineBytes := range bytes.Split(data, []byte{'\n'}) {
line := string(lineBytes)
if len(line) == 0 {
continue
}
// parse config line
if strings.HasPrefix(line, "#") {
continue
}
tokens := strings.Fields(line)
if len(tokens) != 2 {
return nil, fmt.Errorf("malformed line, want 2 fields, got %d: %s", len(tokens), line)
if len(tokens) < 2 {
return nil, fmt.Errorf("malformed line, want at least 2 fields, got %d: %s", len(tokens), line)
}
// parse MAC address
hwaddr, err := net.ParseMAC(tokens[0])
if err != nil {
return nil, fmt.Errorf("malformed hardware address: %s", tokens[0])
}
// parse IP address
ipaddr := net.ParseIP(tokens[1])
if ipaddr.To4() == nil {
return nil, fmt.Errorf("expected an IPv4 address, got: %v", ipaddr)
if v6 && (ipaddr.To16() == nil || ipaddr.To4() != nil) {
return nil, fmt.Errorf("expected an IPv6 address, got: %v", tokens[1])
} else if !v6 && ipaddr.To4() == nil {
return nil, fmt.Errorf("expected an IPv4 address, got: %v", tokens[1])
}
records[hwaddr.String()] = ipaddr
}

return records, nil
}

// LoadDHCPv6Records loads the DHCPv6Records global map with records stored on
// the specified file. The records have to be one per line, a mac address and an
// IPv6 address.
func LoadDHCPv6Records(filename string) (map[string]net.IP, error) {
log.Infof("reading leases from %s", filename)
data, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
records := make(map[string]net.IP)
for _, lineBytes := range bytes.Split(data, []byte{'\n'}) {
line := string(lineBytes)
if len(line) == 0 {
continue
lease := StaticRecord{
Address: ipaddr,
}
if strings.HasPrefix(line, "#") {
continue
}
tokens := strings.Fields(line)
if len(tokens) != 2 {
return nil, fmt.Errorf("malformed line, want 2 fields, got %d: %s", len(tokens), line)
}
hwaddr, err := net.ParseMAC(tokens[0])
if err != nil {
return nil, fmt.Errorf("malformed hardware address: %s", tokens[0])

// parse netmask optionally for IPv4 records
if !v6 && len(tokens) > 2 {
lease.Netmask, err = netmask.ParseNetmask(tokens[2])
if err != nil {
return nil, err
}
}
ipaddr := net.ParseIP(tokens[1])
if ipaddr.To16() == nil || ipaddr.To4() != nil {
return nil, fmt.Errorf("expected an IPv6 address, got: %v", ipaddr)

// parse gateway optionally for IPv4 records
if !v6 && len(tokens) > 3 {
lease.Gateway = net.ParseIP(tokens[3])
if lease.Gateway.To4() == nil {
return nil, fmt.Errorf("expected an IPv4 address, got: %v", tokens[3])
}
}
records[hwaddr.String()] = ipaddr

records[hwaddr.String()] = lease
}

return records, nil
}

Expand All @@ -164,18 +159,18 @@ func Handler6(req, resp dhcpv6.DHCPv6) (dhcpv6.DHCPv6, bool) {
recLock.RLock()
defer recLock.RUnlock()

ipaddr, ok := StaticRecords[mac.String()]
lease, ok := StaticRecords[mac.String()]
if !ok {
log.Warningf("MAC address %s is unknown", mac.String())
return resp, false
}
log.Debugf("found IP address %s for MAC %s", ipaddr, mac.String())
log.Debugf("found IP address %s for MAC %s", lease.Address, mac.String())

resp.AddOption(&dhcpv6.OptIANA{
IaId: m.Options.OneIANA().IaId,
Options: dhcpv6.IdentityOptions{Options: []dhcpv6.Option{
&dhcpv6.OptIAAddress{
IPv6Addr: ipaddr,
IPv6Addr: lease.Address,
PreferredLifetime: 3600 * time.Second,
ValidLifetime: 3600 * time.Second,
},
Expand All @@ -189,13 +184,20 @@ func Handler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool) {
recLock.RLock()
defer recLock.RUnlock()

ipaddr, ok := StaticRecords[req.ClientHWAddr.String()]
lease, ok := StaticRecords[req.ClientHWAddr.String()]
if !ok {
log.Warningf("MAC address %s is unknown", req.ClientHWAddr.String())
return resp, false
}
resp.YourIPAddr = ipaddr
log.Debugf("found IP address %s for MAC %s", ipaddr, req.ClientHWAddr.String())
log.Debugf("found IP address %s for MAC %s", lease.Address, req.ClientHWAddr.String())

resp.YourIPAddr = lease.Address
if len(lease.Netmask) > 0 {
resp.Options.Update(dhcpv4.OptSubnetMask(lease.Netmask))
}
if lease.Gateway.To4() != nil {
resp.Options.Update(dhcpv4.OptRouter(lease.Gateway))
}
return resp, true
}

Expand All @@ -210,7 +212,6 @@ func setup4(args ...string) (handler.Handler4, error) {
}

func setupFile(v6 bool, args ...string) (handler.Handler6, handler.Handler4, error) {
var err error
if len(args) < 1 {
return nil, nil, errors.New("need a file name")
}
Expand All @@ -220,7 +221,7 @@ func setupFile(v6 bool, args ...string) (handler.Handler6, handler.Handler4, err
}

// load initial database from lease file
if err = loadFromFile(v6, filename); err != nil {
if err := loadFromFile(v6, filename); err != nil {
return nil, nil, err
}

Expand Down Expand Up @@ -259,16 +260,11 @@ func setupFile(v6 bool, args ...string) (handler.Handler6, handler.Handler4, err
}

func loadFromFile(v6 bool, filename string) error {
var err error
var records map[string]net.IP
var protver int
protver := 4
if v6 {
protver = 6
records, err = LoadDHCPv6Records(filename)
} else {
protver = 4
records, err = LoadDHCPv4Records(filename)
}
records, err := loadDHCPRecords(v6, filename)
if err != nil {
return fmt.Errorf("failed to load DHCPv%d records: %w", protver, err)
}
Expand Down
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