entries.go

/*
 * Copyright (c) 2017-2020 The qitmeer developers
 */

package qnr

import (
	"fmt"
	"io"
	"net"

	"github.com/Qitmeer/qitmeer/common/encode/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 {
	QNRKey() string
}

type generic struct {
	key   string
	value interface{}
}

func (g generic) QNRKey() 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) QNRKey() string { return "tcp" }

// UDP is the "udp" key, which holds the IPv6-specific UDP port of the node.
type TCP6 uint16

func (v TCP6) QNRKey() string { return "tcp6" }

// UDP is the "udp" key, which holds the UDP port of the node.
type UDP uint16

func (v UDP) QNRKey() string { return "udp" }

// UDP is the "udp" key, which holds the IPv6-specific UDP port of the node.
type UDP6 uint16

func (v UDP6) QNRKey() string { return "udp6" }

// 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) QNRKey() string { return "id" }

// IP is either the "ip" or "ip6" key, depending on the value.
// Use this value to encode IP addresses that can be either v4 or v6.
// To load an address from a record use the IPv4 or IPv6 types.
type IP net.IP

func (v IP) QNRKey() string {
	if net.IP(v).To4() == nil {
		return "ip6"
	}
	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)
	}
	if ip6 := net.IP(v).To16(); ip6 != nil {
		return rlp.Encode(w, ip6)
	}
	return fmt.Errorf("invalid IP address: %v", 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
}

// IPv4 is the "ip" key, which holds the IP address of the node.
type IPv4 net.IP

func (v IPv4) QNRKey() string { return "ip" }

// EncodeRLP implements rlp.Encoder.
func (v IPv4) EncodeRLP(w io.Writer) error {
	ip4 := net.IP(v).To4()
	if ip4 == nil {
		return fmt.Errorf("invalid IPv4 address: %v", net.IP(v))
	}
	return rlp.Encode(w, ip4)
}

// DecodeRLP implements rlp.Decoder.
func (v *IPv4) DecodeRLP(s *rlp.Stream) error {
	if err := s.Decode((*net.IP)(v)); err != nil {
		return err
	}
	if len(*v) != 4 {
		return fmt.Errorf("invalid IPv4 address, want 4 bytes: %v", *v)
	}
	return nil
}

// IPv6 is the "ip6" key, which holds the IP address of the node.
type IPv6 net.IP

func (v IPv6) QNRKey() string { return "ip6" }

// EncodeRLP implements rlp.Encoder.
func (v IPv6) EncodeRLP(w io.Writer) error {
	ip6 := net.IP(v).To16()
	if ip6 == nil {
		return fmt.Errorf("invalid IPv6 address: %v", net.IP(v))
	}
	return rlp.Encode(w, ip6)
}

// DecodeRLP implements rlp.Decoder.
func (v *IPv6) DecodeRLP(s *rlp.Stream) error {
	if err := s.Decode((*net.IP)(v)); err != nil {
		return err
	}
	if len(*v) != 16 {
		return fmt.Errorf("invalid IPv6 address, want 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 QNR key %q", err.Key)
	}
	return fmt.Sprintf("QNR 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
}