79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
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package aghnet
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import (
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"time"
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"github.com/AdguardTeam/AdGuardHome/internal/agherr"
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"github.com/AdguardTeam/golibs/log"
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)
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// DefaultRefreshIvl is the default period of time between refreshing cached
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// addresses.
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// const DefaultRefreshIvl = 5 * time.Minute
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// HostGenFunc is the signature for functions generating fake hostnames. The
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// implementation must be safe for concurrent use.
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type HostGenFunc func() (host string)
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// unit is an alias for an existing map value.
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type unit = struct{}
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// SystemResolvers helps to work with local resolvers' addresses provided by OS.
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type SystemResolvers interface {
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// Get returns the slice of local resolvers' addresses.
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// It should be safe for concurrent use.
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Get() (rs []string)
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// Refresh refreshes the local resolvers' addresses cache. It should be
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// safe for concurrent use.
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Refresh() (err error)
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}
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const (
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// fakeDialErr is an error which dialFunc is expected to return.
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fakeDialErr agherr.Error = "this error signals the successful dialFunc work"
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// badAddrPassedErr is returned when dialFunc can't parse an IP address.
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badAddrPassedErr agherr.Error = "the passed string is not a valid IP address"
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)
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// refreshWithTicker refreshes the cache of sr after each tick form tickCh.
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func refreshWithTicker(sr SystemResolvers, tickCh <-chan time.Time) {
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defer agherr.LogPanic("systemResolvers")
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// TODO(e.burkov): Implement a functionality to stop ticker.
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for range tickCh {
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err := sr.Refresh()
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if err != nil {
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log.Error("systemResolvers: error in refreshing goroutine: %s", err)
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continue
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}
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log.Debug("systemResolvers: local addresses cache is refreshed")
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}
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}
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// NewSystemResolvers returns a SystemResolvers with the cache refresh rate
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// defined by refreshIvl. It disables auto-resfreshing if refreshIvl is 0. If
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// nil is passed for hostGenFunc, the default generator will be used.
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func NewSystemResolvers(
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refreshIvl time.Duration,
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hostGenFunc HostGenFunc,
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) (sr SystemResolvers, err error) {
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sr = newSystemResolvers(refreshIvl, hostGenFunc)
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// Fill cache.
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err = sr.Refresh()
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if err != nil {
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return nil, err
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}
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if refreshIvl > 0 {
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ticker := time.NewTicker(refreshIvl)
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go refreshWithTicker(sr, ticker.C)
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}
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return sr, nil
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}
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