48 lines
990 B
Go
48 lines
990 B
Go
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package resolver
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import (
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"context"
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"sync"
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)
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// CacheResolver is a resolver that caches successful replies.
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type CacheResolver struct {
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ReadOnly bool
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Resolver
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mu sync.Mutex
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cache map[string][]string
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}
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// LookupHost implements Resolver.LookupHost
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func (r *CacheResolver) LookupHost(
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ctx context.Context, hostname string) ([]string, error) {
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if entry := r.Get(hostname); entry != nil {
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return entry, nil
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}
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entry, err := r.Resolver.LookupHost(ctx, hostname)
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if err != nil {
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return nil, err
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}
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if r.ReadOnly == false {
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r.Set(hostname, entry)
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}
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return entry, nil
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}
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// Get gets the currently configured entry for domain, or nil
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func (r *CacheResolver) Get(domain string) []string {
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r.mu.Lock()
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defer r.mu.Unlock()
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return r.cache[domain]
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}
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// Set allows to pre-populate the cache
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func (r *CacheResolver) Set(domain string, addresses []string) {
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r.mu.Lock()
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if r.cache == nil {
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r.cache = make(map[string][]string)
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}
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r.cache[domain] = addresses
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r.mu.Unlock()
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}
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