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dns.go
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dns.go
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package namesys
import (
"errors"
"net"
"strings"
isd "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-is-domain"
context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
path "github.com/ipfs/go-ipfs/path"
)
// DNSResolver implements a Resolver on DNS domains
type DNSResolver struct {
// TODO: maybe some sort of caching?
// cache would need a timeout
}
// CanResolve implements Resolver
func (r *DNSResolver) CanResolve(name string) bool {
return isd.IsDomain(name)
}
// Resolve implements Resolver
// TXT records for a given domain name should contain a b58
// encoded multihash.
func (r *DNSResolver) Resolve(ctx context.Context, name string) (path.Path, error) {
log.Info("DNSResolver resolving %v", name)
txt, err := net.LookupTXT(name)
if err != nil {
return "", err
}
for _, t := range txt {
p, err := parseEntry(t)
if err == nil {
return p, nil
}
}
return "", ErrResolveFailed
}
func parseEntry(txt string) (path.Path, error) {
p, err := path.ParseKeyToPath(txt)
if err == nil {
return p, nil
}
return tryParseDnsLink(txt)
}
func tryParseDnsLink(txt string) (path.Path, error) {
parts := strings.Split(txt, "=")
if len(parts) == 1 || parts[0] != "dnslink" {
return "", errors.New("not a valid dnslink entry")
}
return path.ParsePath(parts[1])
}