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nodeinfo.go
46 lines (40 loc) · 1020 Bytes
/
nodeinfo.go
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package dht
import (
"encoding/binary"
"errors"
"net"
"github.com/anacrolix/missinggo"
)
// The size in bytes of a NodeInfo in its compact binary representation.
const CompactIPv4NodeInfoLen = 26
type NodeInfo struct {
ID [20]byte
Addr Addr
}
// Writes the node info to its compact binary representation in b. See
// CompactNodeInfoLen.
func (ni *NodeInfo) PutCompact(b []byte) error {
if n := copy(b[:], ni.ID[:]); n != 20 {
panic(n)
}
ip := ni.Addr.UDPAddr().IP.To4()
if len(ip) != 4 {
return errors.New("expected ipv4 address")
}
if n := copy(b[20:], ip); n != 4 {
panic(n)
}
binary.BigEndian.PutUint16(b[24:], uint16(ni.Addr.UDPAddr().Port))
return nil
}
func (cni *NodeInfo) UnmarshalCompactIPv4(b []byte) error {
if len(b) != CompactIPv4NodeInfoLen {
return errors.New("expected 26 bytes")
}
missinggo.CopyExact(cni.ID[:], b[:20])
cni.Addr = NewAddr(&net.UDPAddr{
IP: append(make([]byte, 0, 4), b[20:24]...),
Port: int(binary.BigEndian.Uint16(b[24:26])),
})
return nil
}