AdGuardHome/internal/aghnet/systemresolvers_others.go

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//go:build !windows
// +build !windows
package aghnet
import (
"context"
"fmt"
"net"
"strings"
"sync"
"time"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/netutil"
"github.com/AdguardTeam/golibs/stringutil"
)
// defaultHostGen is the default method of generating host for Refresh.
func defaultHostGen() (host string) {
// TODO(e.burkov): Use strings.Builder.
return fmt.Sprintf("test%d.org", time.Now().UnixNano())
}
// systemResolvers is a default implementation of SystemResolvers interface.
type systemResolvers struct {
resolver *net.Resolver
hostGenFunc HostGenFunc
// addrs is the set that contains cached local resolvers' addresses.
addrs *stringutil.Set
addrsLock sync.RWMutex
}
const (
// errBadAddrPassed is returned when dialFunc can't parse an IP address.
errBadAddrPassed errors.Error = "the passed string is not a valid IP address"
// errFakeDial is an error which dialFunc is expected to return.
errFakeDial errors.Error = "this error signals the successful dialFunc work"
// errUnexpectedHostFormat is returned by validateDialedHost when the host has
// more than one percent sign.
errUnexpectedHostFormat errors.Error = "unexpected host format"
)
Pull request: 2704 local addresses vol.2 Merge in DNS/adguard-home from 2704-local-addresses-vol.2 to master Updates #2704. Updates #2829. Squashed commit of the following: commit 507d038c2709de59246fc0b65c3c4ab8e38d1990 Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Mar 31 14:33:05 2021 +0300 aghtest: fix file name commit 8e19f99337bee1d88ad6595adb96f9bb23fa3c41 Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Mar 31 14:06:43 2021 +0300 aghnet: rm redundant mutexes commit 361fa418b33ed160ca20862be1c455ab9378c03f Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Mar 31 13:45:30 2021 +0300 all: fix names, docs commit 14034f4f0230d7aaa3645054946ae5c278089a99 Merge: 35e265cc a72ce1cf Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Mar 31 13:38:15 2021 +0300 Merge branch 'master' into 2704-local-addresses-vol.2 commit 35e265cc8cd308ef1fda414b58c0217cb5f258e4 Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Mar 31 13:33:35 2021 +0300 aghnet: imp naming commit 7a7edac7208a40697d7bc50682b923a144e28e2b Author: Eugene Burkov <e.burkov@adguard.com> Date: Tue Mar 30 20:59:54 2021 +0300 changelog: oops, nope yet commit d26a5d2513daf662ac92053b5e235189a64cc022 Author: Eugene Burkov <e.burkov@adguard.com> Date: Tue Mar 30 20:55:53 2021 +0300 all: some renaming for the glory of semantics commit 9937fa619452b0742616217b975e3ff048d58acb Author: Eugene Burkov <e.burkov@adguard.com> Date: Mon Mar 29 15:34:42 2021 +0300 all: log changes commit d8d9e6dfeea8474466ee25f27021efdd3ddb1592 Author: Eugene Burkov <e.burkov@adguard.com> Date: Fri Mar 26 18:32:23 2021 +0300 all: imp localresolver, imp cutting off own addresses commit 344140df449b85925f19b460fd7dc7c08e29c35a Author: Eugene Burkov <e.burkov@adguard.com> Date: Fri Mar 26 14:53:33 2021 +0300 all: imp code quality commit 1c5c0babec73b125044e23dd3aa75d8eefc19b28 Author: Eugene Burkov <e.burkov@adguard.com> Date: Thu Mar 25 20:44:08 2021 +0300 all: fix go.mod commit 0b9fb3c2369a752e893af8ddc45a86bb9fb27ce5 Author: Eugene Burkov <e.burkov@adguard.com> Date: Thu Mar 25 20:38:51 2021 +0300 all: add error handling commit a7a2e51f57fc6f8f74b95a264ad345cd2a9e026e Merge: c13be634 27f4f052 Author: Eugene Burkov <e.burkov@adguard.com> Date: Thu Mar 25 19:48:36 2021 +0300 Merge branch 'master' into 2704-local-addresses-vol.2 commit c13be634f47bcaed9320a732a51c0e4752d0dad0 Author: Eugene Burkov <e.burkov@adguard.com> Date: Thu Mar 25 18:52:28 2021 +0300 all: cover rdns with tests, imp aghnet functionality commit 48bed9025944530c613ee53e7961d6d5fbabf8be Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Mar 24 20:18:07 2021 +0300 home: make rdns great again commit 1dbacfc8d5b6895807797998317fe3cc814617c1 Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Mar 24 16:07:52 2021 +0300 all: imp external client restriction commit 1208a319a7f4ffe7b7fa8956f245d7a19437c0a4 Author: Eugene Burkov <e.burkov@adguard.com> Date: Mon Mar 22 15:26:45 2021 +0300 all: finish local ptr processor commit c8827fc3db289e1a5d7a11d057743bab39957b02 Author: Eugene Burkov <e.burkov@adguard.com> Date: Tue Mar 2 13:41:22 2021 +0300 all: imp ipdetector, add local ptr processor
2021-03-31 13:00:47 +01:00
func (sr *systemResolvers) refresh() (err error) {
defer func() { err = errors.Annotate(err, "systemResolvers: %w") }()
_, err = sr.resolver.LookupHost(context.Background(), sr.hostGenFunc())
dnserr := &net.DNSError{}
if errors.As(err, &dnserr) && dnserr.Err == errFakeDial.Error() {
return nil
}
return err
}
func newSystemResolvers(refreshIvl time.Duration, hostGenFunc HostGenFunc) (sr SystemResolvers) {
if hostGenFunc == nil {
hostGenFunc = defaultHostGen
}
s := &systemResolvers{
resolver: &net.Resolver{
PreferGo: true,
},
hostGenFunc: hostGenFunc,
addrs: stringutil.NewSet(),
}
s.resolver.Dial = s.dialFunc
return s
}
// validateDialedHost validated the host used by resolvers in dialFunc.
func validateDialedHost(host string) (err error) {
defer func() { err = errors.Annotate(err, "parsing %q: %w", host) }()
var ipStr string
parts := strings.Split(host, "%")
switch len(parts) {
case 1:
ipStr = host
case 2:
// Remove the zone and check the IP address part.
ipStr = parts[0]
default:
return errUnexpectedHostFormat
}
if net.ParseIP(ipStr) == nil {
return errBadAddrPassed
}
return nil
}
// dockerEmbeddedDNS is the address of Docker's embedded DNS server.
//
// See
// https://github.com/moby/moby/blob/v1.12.0/docs/userguide/networking/dockernetworks.md.
const dockerEmbeddedDNS = "127.0.0.11"
// dialFunc gets the resolver's address and puts it into internal cache.
func (sr *systemResolvers) dialFunc(_ context.Context, _, address string) (_ net.Conn, err error) {
// Just validate the passed address is a valid IP.
var host string
host, err = netutil.SplitHost(address)
if err != nil {
// TODO(e.burkov): Maybe use a structured errBadAddrPassed to
// allow unwrapping of the real error.
return nil, fmt.Errorf("%s: %w", err, errBadAddrPassed)
}
// Exclude Docker's embedded DNS server, as it may cause recursion if
// the container is set as the host system's default DNS server.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/3064.
//
// TODO(a.garipov): Perhaps only do this when we are in the container?
// Maybe use an environment variable?
if host == dockerEmbeddedDNS {
return nil, errFakeDial
}
err = validateDialedHost(host)
if err != nil {
return nil, fmt.Errorf("validating dialed host: %w", err)
}
sr.addrsLock.Lock()
defer sr.addrsLock.Unlock()
sr.addrs.Add(host)
return nil, errFakeDial
}
func (sr *systemResolvers) Get() (rs []string) {
sr.addrsLock.RLock()
defer sr.addrsLock.RUnlock()
return sr.addrs.Values()
}