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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package enr
import (
"fmt"
"io"
"net"
"github.com/ethereum/go-ethereum/rlp"
)
// Entry is implemented by known node record entry types.
//
// To define a new entry that is to be included in a node record,
// create a Go type that satisfies this interface. The type should
// also implement rlp.Decoder if additional checks are needed on the value.
type Entry interface {
ENRKey() string
}
type generic struct {
key string
value interface{}
}
func (g generic) ENRKey() string { return g.key }
func (g generic) EncodeRLP(w io.Writer) error {
return rlp.Encode(w, g.value)
}
func (g *generic) DecodeRLP(s *rlp.Stream) error {
return s.Decode(g.value)
}
// WithEntry wraps any value with a key name. It can be used to set and load arbitrary values
// in a record. The value v must be supported by rlp. To use WithEntry with Load, the value
// must be a pointer.
func WithEntry(k string, v interface{}) Entry {
return &generic{key: k, value: v}
}
// TCP is the "tcp" key, which holds the TCP port of the node.
type TCP uint16
func (v TCP) ENRKey() string { return "tcp" }
// UDP is the "udp" key, which holds the UDP port of the node.
type UDP uint16
func (v UDP) ENRKey() string { return "udp" }
// ID is the "id" key, which holds the name of the identity scheme.
type ID string
const IDv4 = ID("v4") // the default identity scheme
func (v ID) ENRKey() string { return "id" }
// IP is the "ip" key, which holds the IP address of the node.
type IP net.IP
func (v IP) ENRKey() string { return "ip" }
// EncodeRLP implements rlp.Encoder.
func (v IP) EncodeRLP(w io.Writer) error {
if ip4 := net.IP(v).To4(); ip4 != nil {
return rlp.Encode(w, ip4)
}
return rlp.Encode(w, net.IP(v))
}
// DecodeRLP implements rlp.Decoder.
func (v *IP) DecodeRLP(s *rlp.Stream) error {
if err := s.Decode((*net.IP)(v)); err != nil {
return err
}
if len(*v) != 4 && len(*v) != 16 {
return fmt.Errorf("invalid IP address, want 4 or 16 bytes: %v", *v)
}
return nil
}
// KeyError is an error related to a key.
type KeyError struct {
Key string
Err error
}
// Error implements error.
func (err *KeyError) Error() string {
if err.Err == errNotFound {
return fmt.Sprintf("missing ENR key %q", err.Key)
}
return fmt.Sprintf("ENR key %q: %v", err.Key, err.Err)
}
// IsNotFound reports whether the given error means that a key/value pair is
// missing from a record.
func IsNotFound(err error) bool {
kerr, ok := err.(*KeyError)
return ok && kerr.Err == errNotFound
}
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