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namesys.go
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namesys.go
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package namesys
import (
"context"
"errors"
"gx/ipfs/QmXYjuNuxVzXKJCfWasQk1RqkhVLDM9jtUKhqc2WPQmFSB/go-libp2p-peer"
"strings"
"time"
)
// ErrResolveFailed signals an error when attempting to resolve.
var ErrResolveFailed = errors.New("Could not resolve name.")
// ErrNoResolver signals no resolver exists for the specified domain.
var ErrNoResolver = errors.New("No resover for domain.")
const cacheTTL = time.Minute
type NameSystem struct {
resolvers map[string]Resolver
cache map[string]cachedName
}
type cachedName struct {
id peer.ID
expiration time.Time
}
func NewNameSystem(resolvers []Resolver) (*NameSystem, error) {
n := &NameSystem{
resolvers: make(map[string]Resolver),
cache: make(map[string]cachedName),
}
for _, r := range resolvers {
for _, domain := range r.Domains() {
n.resolvers[domain] = r
}
}
return n, nil
}
func (n *NameSystem) Resolve(ctx context.Context, name string) (pid peer.ID, err error) {
pid, err = peer.IDB58Decode(name)
if err == nil {
return pid, nil
}
split := strings.Split(name, ".")
ext := split[len(split)-1]
cn, ok := n.cache[name]
if ok {
if cn.expiration.Before(time.Now()) {
return cn.id, nil
}
}
r, ok := n.resolvers[ext]
if ok {
pid, err = r.Resolve(ctx, name)
if err != nil {
return pid, err
}
n.cache[name] = cachedName{pid, time.Now().Add(cacheTTL)}
return pid, nil
}
dnsResolver, ok := n.resolvers["dns"]
if ok {
pid, err = dnsResolver.Resolve(ctx, name)
if err != nil {
return pid, err
}
n.cache[name] = cachedName{pid, time.Now().Add(cacheTTL)}
return pid, nil
}
return pid, ErrNoResolver
}