AdGuardHome/internal/aghnet/ipset_linux.go

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//go:build linux
// +build linux
package aghnet
import (
"fmt"
"net"
"strings"
"sync"
"github.com/AdguardTeam/golibs/errors"
"github.com/digineo/go-ipset/v2"
"github.com/mdlayher/netlink"
"github.com/ti-mo/netfilter"
)
// How to test on a real Linux machine:
//
// 1. Run:
//
// sudo ipset create example_set hash:ip family ipv4
//
// 2. Run:
//
// sudo ipset list example_set
//
// The Members field should be empty.
//
// 3. Add the line "example.com/example_set" to your AdGuardHome.yaml.
//
// 4. Start AdGuardHome.
//
// 5. Make requests to example.com and its subdomains.
//
// 6. Run:
//
// sudo ipset list example_set
//
// The Members field should contain the resolved IP addresses.
// newIpsetMgr returns a new Linux ipset manager.
func newIpsetMgr(ipsetConf []string) (set IpsetManager, err error) {
dial := func(pf netfilter.ProtoFamily, conf *netlink.Config) (conn ipsetConn, err error) {
return ipset.Dial(pf, conf)
}
return newIpsetMgrWithDialer(ipsetConf, dial)
}
// ipsetConn is the ipset conn interface.
type ipsetConn interface {
Add(name string, entries ...*ipset.Entry) (err error)
Close() (err error)
Header(name string) (p *ipset.HeaderPolicy, err error)
}
// ipsetDialer creates an ipsetConn.
type ipsetDialer func(pf netfilter.ProtoFamily, conf *netlink.Config) (conn ipsetConn, err error)
// ipsetProps contains one Linux Netfilter ipset properties.
type ipsetProps struct {
name string
family netfilter.ProtoFamily
}
// unit is a convenient alias for struct{}.
type unit = struct{}
// ipsetMgr is the Linux Netfilter ipset manager.
type ipsetMgr struct {
nameToIpset map[string]ipsetProps
domainToIpsets map[string][]ipsetProps
dial ipsetDialer
// mu protects all properties below.
mu *sync.Mutex
// TODO(a.garipov): Currently, the ipset list is static, and we don't
// read the IPs already in sets, so we can assume that all incoming IPs
// are either added to all corresponding ipsets or not. When that stops
// being the case, for example if we add dynamic reconfiguration of
// ipsets, this map will need to become a per-ipset-name one.
addedIPs map[[16]byte]unit
ipv4Conn ipsetConn
ipv6Conn ipsetConn
}
// dialNetfilter establishes connections to Linux's netfilter module.
func (m *ipsetMgr) dialNetfilter(conf *netlink.Config) (err error) {
// The kernel API does not actually require two sockets but package
// github.com/digineo/go-ipset does.
//
// TODO(a.garipov): Perhaps we can ditch package ipset altogether and
// just use packages netfilter and netlink.
m.ipv4Conn, err = m.dial(netfilter.ProtoIPv4, conf)
if err != nil {
return fmt.Errorf("dialing v4: %w", err)
}
m.ipv6Conn, err = m.dial(netfilter.ProtoIPv6, conf)
if err != nil {
return fmt.Errorf("dialing v6: %w", err)
}
return nil
}
// parseIpsetConfig parses one ipset configuration string.
func parseIpsetConfig(confStr string) (hosts, ipsetNames []string, err error) {
confStr = strings.TrimSpace(confStr)
hostsAndNames := strings.Split(confStr, "/")
if len(hostsAndNames) != 2 {
return nil, nil, fmt.Errorf("invalid value %q: expected one slash", confStr)
}
hosts = strings.Split(hostsAndNames[0], ",")
ipsetNames = strings.Split(hostsAndNames[1], ",")
if len(ipsetNames) == 0 {
return nil, nil, nil
}
for i := range ipsetNames {
ipsetNames[i] = strings.TrimSpace(ipsetNames[i])
if len(ipsetNames[i]) == 0 {
return nil, nil, fmt.Errorf("invalid value %q: empty ipset name", confStr)
}
}
for i := range hosts {
hosts[i] = strings.ToLower(strings.TrimSpace(hosts[i]))
}
return hosts, ipsetNames, nil
}
// ipsetProps returns the properties of an ipset with the given name.
func (m *ipsetMgr) ipsetProps(name string) (set ipsetProps, err error) {
// The family doesn't seem to matter when we use a header query, so
// query only the IPv4 one.
//
// TODO(a.garipov): Find out if this is a bug or a feature.
var res *ipset.HeaderPolicy
res, err = m.ipv4Conn.Header(name)
if err != nil {
return set, err
}
if res == nil || res.Family == nil {
return set, errors.Error("empty response or no family data")
}
family := netfilter.ProtoFamily(res.Family.Value)
if family != netfilter.ProtoIPv4 && family != netfilter.ProtoIPv6 {
return set, fmt.Errorf("unexpected ipset family %d", family)
}
return ipsetProps{
name: name,
family: family,
}, nil
}
// ipsets returns currently known ipsets.
func (m *ipsetMgr) ipsets(names []string) (sets []ipsetProps, err error) {
for _, name := range names {
set, ok := m.nameToIpset[name]
if ok {
sets = append(sets, set)
continue
}
set, err = m.ipsetProps(name)
if err != nil {
return nil, fmt.Errorf("querying ipset %q: %w", name, err)
}
m.nameToIpset[name] = set
sets = append(sets, set)
}
return sets, nil
}
// newIpsetMgrWithDialer returns a new Linux ipset manager using the provided
// dialer.
func newIpsetMgrWithDialer(ipsetConf []string, dial ipsetDialer) (mgr IpsetManager, err error) {
defer func() { err = errors.Annotate(err, "ipset: %w") }()
m := &ipsetMgr{
mu: &sync.Mutex{},
nameToIpset: make(map[string]ipsetProps),
domainToIpsets: make(map[string][]ipsetProps),
dial: dial,
addedIPs: make(map[[16]byte]unit),
}
err = m.dialNetfilter(&netlink.Config{})
if err != nil {
return nil, fmt.Errorf("dialing netfilter: %w", err)
}
for i, confStr := range ipsetConf {
var hosts, ipsetNames []string
hosts, ipsetNames, err = parseIpsetConfig(confStr)
if err != nil {
return nil, fmt.Errorf("config line at idx %d: %w", i, err)
}
var ipsets []ipsetProps
ipsets, err = m.ipsets(ipsetNames)
if err != nil {
return nil, fmt.Errorf(
"getting ipsets from config line at idx %d: %w",
i,
err,
)
}
for _, host := range hosts {
m.domainToIpsets[host] = append(m.domainToIpsets[host], ipsets...)
}
}
return m, nil
}
// lookupHost find the ipsets for the host, taking subdomain wildcards into
// account.
func (m *ipsetMgr) lookupHost(host string) (sets []ipsetProps) {
// Search for matching ipset hosts starting with most specific domain.
// We could use a trie here but the simple, inefficient solution isn't
// that expensive: ~10 ns for TLD + SLD vs. ~140 ns for 10 subdomains on
// an AMD Ryzen 7 PRO 4750U CPU; ~120 ns vs. ~ 1500 ns on a Raspberry
// Pi's ARMv7 rev 4 CPU.
for i := 0; ; i++ {
host = host[i:]
sets = m.domainToIpsets[host]
if sets != nil {
return sets
}
i = strings.Index(host, ".")
if i == -1 {
break
}
}
// Check the root catch-all one.
return m.domainToIpsets[""]
}
// addIPs adds the IP addresses for the host to the ipset. set must be same
// family as set's family.
func (m *ipsetMgr) addIPs(host string, set ipsetProps, ips []net.IP) (n int, err error) {
if len(ips) == 0 {
return 0, nil
}
var entries []*ipset.Entry
var newAddedIPs [][16]byte
for _, ip := range ips {
var iparr [16]byte
copy(iparr[:], ip.To16())
if _, added := m.addedIPs[iparr]; added {
continue
}
entries = append(entries, ipset.NewEntry(ipset.EntryIP(ip)))
newAddedIPs = append(newAddedIPs, iparr)
}
n = len(entries)
if n == 0 {
return 0, nil
}
var conn ipsetConn
switch set.family {
case netfilter.ProtoIPv4:
conn = m.ipv4Conn
case netfilter.ProtoIPv6:
conn = m.ipv6Conn
default:
return 0, fmt.Errorf("unexpected family %s for ipset %q", set.family, set.name)
}
err = conn.Add(set.name, entries...)
if err != nil {
return 0, fmt.Errorf("adding %q%s to ipset %q: %w", host, ips, set.name, err)
}
// Only add these to the cache once we're sure that all of them were
// actually sent to the ipset.
for _, iparr := range newAddedIPs {
m.addedIPs[iparr] = unit{}
}
return n, nil
}
// addToSets adds the IP addresses to the corresponding ipset.
func (m *ipsetMgr) addToSets(
host string,
ip4s []net.IP,
ip6s []net.IP,
sets []ipsetProps,
) (n int, err error) {
for _, set := range sets {
var nn int
switch set.family {
case netfilter.ProtoIPv4:
nn, err = m.addIPs(host, set, ip4s)
if err != nil {
return n, err
}
case netfilter.ProtoIPv6:
nn, err = m.addIPs(host, set, ip6s)
if err != nil {
return n, err
}
default:
return n, fmt.Errorf("unexpected family %s for ipset %q", set.family, set.name)
}
n += nn
}
return n, nil
}
// Add implements the IpsetManager interface for *ipsetMgr
func (m *ipsetMgr) Add(host string, ip4s, ip6s []net.IP) (n int, err error) {
m.mu.Lock()
defer m.mu.Unlock()
sets := m.lookupHost(host)
if len(sets) == 0 {
return 0, nil
}
return m.addToSets(host, ip4s, ip6s, sets)
}
// Close implements the IpsetManager interface for *ipsetMgr.
func (m *ipsetMgr) Close() (err error) {
m.mu.Lock()
defer m.mu.Unlock()
var errs []error
// Close both and collect errors so that the errors from closing one
// don't interfere with closing the other.
err = m.ipv4Conn.Close()
if err != nil {
errs = append(errs, err)
}
err = m.ipv6Conn.Close()
if err != nil {
errs = append(errs, err)
}
if len(errs) != 0 {
return errors.List("closing ipsets", errs...)
}
return nil
}