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// Copyright 2018-present the CoreDHCP Authors. All rights reserved
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
package rangeplugin
import (
"database/sql"
"encoding/binary"
"errors"
"fmt"
"net"
"sync"
"time"
"github.com/coredhcp/coredhcp/handler"
"github.com/coredhcp/coredhcp/logger"
"github.com/coredhcp/coredhcp/plugins"
"github.com/coredhcp/coredhcp/plugins/allocators"
"github.com/coredhcp/coredhcp/plugins/allocators/bitmap"
"github.com/insomniacslk/dhcp/dhcpv4"
)
var log = logger.GetLogger("plugins/range")
// Plugin wraps plugin registration information
var Plugin = plugins.Plugin{
Name: "range",
Setup4: setupRange,
}
//Record holds an IP lease record
type Record struct {
IP net.IP
expires int
hostname string
}
// PluginState is the data held by an instance of the range plugin
type PluginState struct {
// Rough lock for the whole plugin, we'll get better performance once we use leasestorage
sync.Mutex
// Recordsv4 holds a MAC -> IP address and lease time mapping
Recordsv4 map[string]*Record
LeaseTime time.Duration
leasedb *sql.DB
allocator allocators.Allocator
}
// Handler4 handles DHCPv4 packets for the range plugin
func (p *PluginState) Handler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool) {
p.Lock()
defer p.Unlock()
record, ok := p.Recordsv4[req.ClientHWAddr.String()]
hostname := req.HostName()
if !ok {
// Allocating new address since there isn't one allocated
log.Printf("MAC address %s is new, leasing new IPv4 address", req.ClientHWAddr.String())
ip, err := p.allocator.Allocate(net.IPNet{})
if err != nil {
log.Errorf("Could not allocate IP for MAC %s: %v", req.ClientHWAddr.String(), err)
return nil, true
}
rec := Record{
IP: ip.IP.To4(),
expires: int(time.Now().Add(p.LeaseTime).Unix()),
hostname: hostname,
}
err = p.saveIPAddress(req.ClientHWAddr, &rec)
if err != nil {
log.Errorf("SaveIPAddress for MAC %s failed: %v", req.ClientHWAddr.String(), err)
}
p.Recordsv4[req.ClientHWAddr.String()] = &rec
record = &rec
} else {
// Ensure we extend the existing lease at least past when the one we're giving expires
expiry := time.Unix(int64(record.expires), 0)
if expiry.Before(time.Now().Add(p.LeaseTime)) {
record.expires = int(time.Now().Add(p.LeaseTime).Round(time.Second).Unix())
record.hostname = hostname
err := p.saveIPAddress(req.ClientHWAddr, record)
if err != nil {
log.Errorf("Could not persist lease for MAC %s: %v", req.ClientHWAddr.String(), err)
}
}
}
resp.YourIPAddr = record.IP
resp.Options.Update(dhcpv4.OptIPAddressLeaseTime(p.LeaseTime.Round(time.Second)))
log.Printf("found IP address %s for MAC %s", record.IP, req.ClientHWAddr.String())
return resp, false
}
func setupRange(args ...string) (handler.Handler4, error) {
var (
err error
p PluginState
)
if len(args) < 4 {
return nil, fmt.Errorf("invalid number of arguments, want: 4 (file name, start IP, end IP, lease time), got: %d", len(args))
}
filename := args[0]
if filename == "" {
return nil, errors.New("file name cannot be empty")
}
ipRangeStart := net.ParseIP(args[1])
if ipRangeStart.To4() == nil {
return nil, fmt.Errorf("invalid IPv4 address: %v", args[1])
}
ipRangeEnd := net.ParseIP(args[2])
if ipRangeEnd.To4() == nil {
return nil, fmt.Errorf("invalid IPv4 address: %v", args[2])
}
if binary.BigEndian.Uint32(ipRangeStart.To4()) > binary.BigEndian.Uint32(ipRangeEnd.To4()) {
return nil, errors.New("start of IP range has to be lower than or equal to the end of an IP range")
}
p.allocator, err = bitmap.NewIPv4Allocator(ipRangeStart, ipRangeEnd)
if err != nil {
return nil, fmt.Errorf("could not create an allocator: %w", err)
}
p.LeaseTime, err = time.ParseDuration(args[3])
if err != nil {
return nil, fmt.Errorf("invalid lease duration: %v", args[3])
}
if err := p.registerBackingDB(filename); err != nil {
return nil, fmt.Errorf("could not setup lease storage: %w", err)
}
p.Recordsv4, err = loadRecords(p.leasedb)
if err != nil {
return nil, fmt.Errorf("could not load records from file: %v", err)
}
log.Printf("Loaded %d DHCPv4 leases from %s", len(p.Recordsv4), filename)
for _, v := range p.Recordsv4 {
ip, err := p.allocator.Allocate(net.IPNet{IP: v.IP})
if err != nil {
return nil, fmt.Errorf("failed to re-allocate leased ip %v: %v", v.IP.String(), err)
}
if ip.IP.String() != v.IP.String() {
return nil, fmt.Errorf("allocator did not re-allocate requested leased ip %v: %v", v.IP.String(), ip.String())
}
}
return p.Handler4, nil
}
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