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nodeinfo.go
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nodeinfo.go
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package dht
import (
"bytes"
"encoding"
"encoding/binary"
"fmt"
"github.com/anacrolix/missinggo/v2/slices"
"github.com/anacrolix/torrent/bencode"
"github.com/bitmagnet-io/bitmagnet/internal/protocol"
"math"
"math/rand"
"net"
"reflect"
)
type NodeInfo struct {
ID protocol.ID
Addr NodeAddr
}
func (ni NodeInfo) String() string {
return fmt.Sprintf("{%x at %s}", ni.ID, ni.Addr)
}
func RandomNodeInfo(ipLen int) (ni NodeInfo) {
ni.ID = protocol.RandomNodeID()
ni.Addr.Port = rand.Intn(math.MaxUint16 + 1)
ni.Addr.IP = make(net.IP, ipLen)
for i := 0; i < ipLen; i++ {
ni.Addr.IP[i] = byte(rand.Intn(256))
}
return
}
var _ interface {
encoding.BinaryMarshaler
encoding.BinaryUnmarshaler
} = (*NodeInfo)(nil)
func (ni NodeInfo) MarshalBinary() ([]byte, error) {
var w bytes.Buffer
w.Write(ni.ID[:])
w.Write(ni.Addr.IP)
if err := binary.Write(&w, binary.BigEndian, uint16(ni.Addr.Port)); err != nil {
return nil, err
}
return w.Bytes(), nil
}
func (ni *NodeInfo) UnmarshalBinary(b []byte) error {
copy(ni.ID[:], b)
return ni.Addr.UnmarshalBinary(b[20:])
}
type (
CompactIPv4NodeInfo []NodeInfo
)
func (CompactIPv4NodeInfo) ElemSize() int {
return 26
}
// func (me *CompactIPv4NodeInfo) Scrub() {
// slices.FilterInPlace(me, func(ni *NodeInfo) bool {
// ni.Addr.IP = ni.Addr.IP.To4()
// return ni.Addr.IP != nil
// })
// }
func (ni CompactIPv4NodeInfo) MarshalBinary() ([]byte, error) {
return marshalBinarySlice(slices.Map(func(ni NodeInfo) NodeInfo {
ni.Addr.IP = ni.Addr.IP.To4()
return ni
}, ni).(CompactIPv4NodeInfo))
}
func (ni CompactIPv4NodeInfo) MarshalBencode() ([]byte, error) {
return bencodeBytesResult(ni.MarshalBinary())
}
func (ni *CompactIPv4NodeInfo) UnmarshalBinary(b []byte) error {
return unmarshalBinarySlice(ni, b)
}
func (ni *CompactIPv4NodeInfo) UnmarshalBencode(b []byte) error {
return unmarshalBencodedBinary(ni, b)
}
func unmarshalBencodedBinary(u encoding.BinaryUnmarshaler, b []byte) (err error) {
var ub string
err = bencode.Unmarshal(b, &ub)
if err != nil {
return
}
return u.UnmarshalBinary([]byte(ub))
}
type elemSizer interface {
ElemSize() int
}
func unmarshalBinarySlice(slice elemSizer, b []byte) (err error) {
sliceValue := reflect.ValueOf(slice).Elem()
elemType := sliceValue.Type().Elem()
bytesPerElem := slice.ElemSize()
elem := reflect.New(elemType)
for len(b) != 0 {
if len(b) < bytesPerElem {
err = fmt.Errorf("%d trailing bytes < %d required for element", len(b), bytesPerElem)
break
}
if bu, ok := elem.Interface().(encoding.BinaryUnmarshaler); ok {
err = bu.UnmarshalBinary(b[:bytesPerElem])
} else if elem.Elem().Len() == bytesPerElem {
reflect.Copy(elem.Elem(), reflect.ValueOf(b[:bytesPerElem]))
} else {
err = fmt.Errorf("can't unmarshal %v bytes into %v", bytesPerElem, elem.Type())
}
if err != nil {
return
}
sliceValue.Set(reflect.Append(sliceValue, elem.Elem()))
b = b[bytesPerElem:]
}
return
}
func marshalBinarySlice(slice elemSizer) (ret []byte, err error) {
var elems []encoding.BinaryMarshaler
makeInto(&elems, slice)
for _, e := range elems {
var b []byte
b, err = e.MarshalBinary()
if err != nil {
return
}
if len(b) != slice.ElemSize() {
panic(fmt.Sprintf("marshalled %d bytes, but expected %d", len(b), slice.ElemSize()))
}
ret = append(ret, b...)
}
return
}
func bencodeBytesResult(b []byte, err error) ([]byte, error) {
if err != nil {
return b, err
}
return bencode.Marshal(b)
}
// makes and sets a slice at *ptrTo, and type asserts all the elements from "from" to it.
func makeInto(ptrTo interface{}, from interface{}) {
fromSliceValue := reflect.ValueOf(from)
fromLen := fromSliceValue.Len()
if fromLen == 0 {
return
}
// Deref the pointer to slice.
slicePtrValue := reflect.ValueOf(ptrTo)
if slicePtrValue.Kind() != reflect.Ptr {
panic("destination is not a pointer")
}
destSliceValue := slicePtrValue.Elem()
// The type of the elements of the destination slice.
destSliceElemType := destSliceValue.Type().Elem()
destSliceValue.Set(reflect.MakeSlice(destSliceValue.Type(), fromLen, fromLen))
for i := range make([]struct{}, fromSliceValue.Len()) {
// The value inside the interface in the slice element.
itemValue := fromSliceValue.Index(i)
if itemValue.Kind() == reflect.Interface {
itemValue = itemValue.Elem()
}
convertedItem := itemValue.Convert(destSliceElemType)
destSliceValue.Index(i).Set(convertedItem)
}
}