AdGuardHome/internal/aghnet/systemresolvers_windows.go

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//go:build windows
// +build windows
package aghnet
import (
"bufio"
"fmt"
"io"
"net"
"os/exec"
"strings"
"sync"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/log"
)
// systemResolvers implementation differs for Windows since Go's resolver
// doesn't work there.
//
// See https://github.com/golang/go/issues/33097.
type systemResolvers struct {
// addrs is the slice of cached local resolvers' addresses.
addrs []string
addrsLock sync.RWMutex
}
func newSystemResolvers(_ HostGenFunc) (sr SystemResolvers) {
return &systemResolvers{}
}
func (sr *systemResolvers) Get() (rs []string) {
sr.addrsLock.RLock()
defer sr.addrsLock.RUnlock()
addrs := sr.addrs
rs = make([]string, len(addrs))
copy(rs, addrs)
return rs
}
// writeExit writes "exit" to w and closes it. It is supposed to be run in
// a goroutine.
func writeExit(w io.WriteCloser) {
defer log.OnPanic("systemResolvers: writeExit")
defer func() {
derr := w.Close()
if derr != nil {
log.Error("systemResolvers: writeExit: closing: %s", derr)
}
}()
_, err := io.WriteString(w, "exit")
if err != nil {
log.Error("systemResolvers: writeExit: writing: %s", err)
}
}
// scanAddrs scans the DNS addresses from nslookup's output. The expected
// output of nslookup looks like this:
//
// Default Server: 192-168-1-1.qualified.domain.ru
// Address: 192.168.1.1
//
func scanAddrs(s *bufio.Scanner) (addrs []string) {
for s.Scan() {
line := strings.TrimSpace(s.Text())
fields := strings.Fields(line)
if len(fields) != 2 || fields[0] != "Address:" {
continue
}
// If the address contains port then it is separated with '#'.
ipPort := strings.Split(fields[1], "#")
if len(ipPort) == 0 {
continue
}
addr := ipPort[0]
if net.ParseIP(addr) == nil {
log.Debug("systemResolvers: %q is not a valid ip", addr)
continue
}
addrs = append(addrs, addr)
}
return addrs
}
// getAddrs gets local resolvers' addresses from OS in a special Windows way.
//
// TODO(e.burkov): This whole function needs more detailed research on getting
// local resolvers addresses on Windows. We execute the external command for
// now that is not the most accurate way.
func (sr *systemResolvers) getAddrs() (addrs []string, err error) {
var cmdPath string
cmdPath, err = exec.LookPath("nslookup.exe")
if err != nil {
return nil, fmt.Errorf("looking up cmd path: %w", err)
}
cmd := exec.Command(cmdPath)
var stdin io.WriteCloser
stdin, err = cmd.StdinPipe()
if err != nil {
return nil, fmt.Errorf("getting the command's stdin pipe: %w", err)
}
var stdout io.ReadCloser
stdout, err = cmd.StdoutPipe()
if err != nil {
return nil, fmt.Errorf("getting the command's stdout pipe: %w", err)
}
go writeExit(stdin)
err = cmd.Start()
if err != nil {
return nil, fmt.Errorf("start command executing: %w", err)
}
s := bufio.NewScanner(stdout)
addrs = scanAddrs(s)
err = cmd.Wait()
if err != nil {
return nil, fmt.Errorf("executing the command: %w", err)
}
err = s.Err()
if err != nil {
return nil, fmt.Errorf("scanning output: %w", err)
}
// Don't close StdoutPipe since Wait do it for us in ¿most? cases.
//
// See go doc os/exec.Cmd.StdoutPipe.
return addrs, nil
}
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") }()
got, err := sr.getAddrs()
if err != nil {
return fmt.Errorf("can't get addresses: %w", err)
}
if len(got) == 0 {
return nil
}
sr.addrsLock.Lock()
defer sr.addrsLock.Unlock()
sr.addrs = got
return nil
}