97 lines
2.1 KiB
Go
97 lines
2.1 KiB
Go
// +build !windows
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package aghnet
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import (
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"context"
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"errors"
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"fmt"
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"net"
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"sync"
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"time"
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"github.com/AdguardTeam/AdGuardHome/internal/agherr"
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)
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// defaultHostGen is the default method of generating host for Refresh.
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func defaultHostGen() (host string) {
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// TODO(e.burkov): Use strings.Builder.
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return fmt.Sprintf("test%d.org", time.Now().UnixNano())
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}
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// systemResolvers is a default implementation of SystemResolvers interface.
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type systemResolvers struct {
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resolver *net.Resolver
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hostGenFunc HostGenFunc
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// addrs is the map that contains cached local resolvers' addresses.
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addrs map[string]unit
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addrsLock sync.RWMutex
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}
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func (sr *systemResolvers) refresh() (err error) {
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defer agherr.Annotate("systemResolvers: %w", &err)
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_, err = sr.resolver.LookupHost(context.Background(), sr.hostGenFunc())
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dnserr := &net.DNSError{}
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if errors.As(err, &dnserr) && dnserr.Err == fakeDialErr.Error() {
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return nil
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}
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return err
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}
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func newSystemResolvers(refreshIvl time.Duration, hostGenFunc HostGenFunc) (sr SystemResolvers) {
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if hostGenFunc == nil {
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hostGenFunc = defaultHostGen
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}
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s := &systemResolvers{
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resolver: &net.Resolver{
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PreferGo: true,
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},
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hostGenFunc: hostGenFunc,
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addrs: make(map[string]unit),
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}
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s.resolver.Dial = s.dialFunc
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return s
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}
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// dialFunc gets the resolver's address and puts it into internal cache.
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func (sr *systemResolvers) dialFunc(_ context.Context, _, address string) (_ net.Conn, err error) {
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// Just validate the passed address is a valid IP.
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var host string
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host, err = SplitHost(address)
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if err != nil {
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// TODO(e.burkov): Maybe use a structured badAddrPassedErr to
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// allow unwrapping of the real error.
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return nil, fmt.Errorf("%s: %w", err, badAddrPassedErr)
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}
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if net.ParseIP(host) == nil {
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return nil, fmt.Errorf("parsing %q: %w", host, badAddrPassedErr)
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}
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sr.addrsLock.Lock()
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defer sr.addrsLock.Unlock()
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sr.addrs[host] = unit{}
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return nil, fakeDialErr
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}
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func (sr *systemResolvers) Get() (rs []string) {
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sr.addrsLock.RLock()
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defer sr.addrsLock.RUnlock()
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addrs := sr.addrs
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rs = make([]string, len(addrs))
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var i int
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for addr := range addrs {
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rs[i] = addr
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i++
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}
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return rs
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}
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