reflector.go/dht/message.go

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package dht
import (
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"crypto/rand"
"encoding/hex"
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"reflect"
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"strconv"
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"strings"
"github.com/lbryio/lbry.go/errors"
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"github.com/lbryio/reflector.go/dht/bits"
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"github.com/lyoshenka/bencode"
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"github.com/spf13/cast"
)
const (
pingMethod = "ping"
storeMethod = "store"
findNodeMethod = "findNode"
findValueMethod = "findValue"
)
const (
pingSuccessResponse = "pong"
storeSuccessResponse = "OK"
)
const (
requestType = 0
responseType = 1
errorType = 2
)
const (
// these are strings because bencode requires bytestring keys
headerTypeField = "0"
headerMessageIDField = "1" // message id is 20 bytes long
headerNodeIDField = "2" // node id is 48 bytes long
headerPayloadField = "3"
headerArgsField = "4"
contactsField = "contacts"
tokenField = "token"
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protocolVersionField = "protocolVersion"
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)
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// Message is a DHT message
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type Message interface {
bencode.Marshaler
}
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type messageID [messageIDLength]byte
// HexShort returns the first 8 hex characters of the hex encoded message id.
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func (m messageID) HexShort() string {
return hex.EncodeToString(m[:])[:8]
}
// UnmarshalBencode takes a byte slice and unmarshals the message id.
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func (m *messageID) UnmarshalBencode(encoded []byte) error {
var str string
err := bencode.DecodeBytes(encoded, &str)
if err != nil {
return err
}
copy(m[:], str)
return nil
}
// MarshallBencode returns the encoded byte slice of the message id.
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func (m messageID) MarshalBencode() ([]byte, error) {
str := string(m[:])
return bencode.EncodeBytes(str)
}
func newMessageID() messageID {
var m messageID
_, err := rand.Read(m[:])
if err != nil {
panic(err)
}
return m
}
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// Request represents a DHT request message
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type Request struct {
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ID messageID
NodeID bits.Bitmap
Method string
Arg *bits.Bitmap
StoreArgs *storeArgs
ProtocolVersion int
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}
// MarshalBencode returns the serialized byte slice representation of the request
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func (r Request) MarshalBencode() ([]byte, error) {
var args interface{}
if r.StoreArgs != nil {
args = r.StoreArgs
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} else if r.Arg != nil {
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args = []bits.Bitmap{*r.Arg}
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} else {
args = []string{} // request must always have keys 0-4, so we use an empty list for PING
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}
return bencode.EncodeBytes(map[string]interface{}{
headerTypeField: requestType,
headerMessageIDField: r.ID,
headerNodeIDField: r.NodeID,
headerPayloadField: r.Method,
headerArgsField: args,
})
}
// UnmarshalBencode unmarshals the serialized byte slice into the appropriate fields of the request.
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func (r *Request) UnmarshalBencode(b []byte) error {
var raw struct {
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ID messageID `bencode:"1"`
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NodeID bits.Bitmap `bencode:"2"`
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Method string `bencode:"3"`
Args bencode.RawMessage `bencode:"4"`
}
err := bencode.DecodeBytes(b, &raw)
if err != nil {
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return errors.Prefix("request unmarshal", err)
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}
r.ID = raw.ID
r.NodeID = raw.NodeID
r.Method = raw.Method
if r.Method == storeMethod {
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r.StoreArgs = &storeArgs{} // bencode wont find the unmarshaler on a null pointer. need to fix it.
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err = bencode.DecodeBytes(raw.Args, &r.StoreArgs)
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if err != nil {
return errors.Prefix("request unmarshal", err)
}
} else if len(raw.Args) > 2 { // 2 because an empty list is `le`
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r.Arg, r.ProtocolVersion, err = processArgsAndProtoVersion(raw.Args)
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if err != nil {
return errors.Prefix("request unmarshal", err)
}
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}
return nil
}
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func processArgsAndProtoVersion(raw bencode.RawMessage) (arg *bits.Bitmap, version int, err error) {
var args []bencode.RawMessage
err = bencode.DecodeBytes(raw, &args)
if err != nil {
return nil, 0, err
}
if len(args) == 0 {
return nil, 0, nil
}
var extras map[string]int
err = bencode.DecodeBytes(args[len(args)-1], &extras)
if err == nil {
if v, exists := extras[protocolVersionField]; exists {
version = v
args = args[:len(args)-1]
}
}
if len(args) > 0 {
var b bits.Bitmap
err = bencode.DecodeBytes(args[0], &b)
if err != nil {
return nil, 0, err
}
arg = &b
}
return arg, version, nil
}
func (r Request) argsDebug() string {
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if r.StoreArgs != nil {
return r.StoreArgs.BlobHash.HexShort() + ", " + r.StoreArgs.Value.LbryID.HexShort() + ":" + strconv.Itoa(r.StoreArgs.Value.Port)
} else if r.Arg != nil {
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return r.Arg.HexShort()
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}
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return ""
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}
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type storeArgsValue struct {
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Token string `bencode:"token"`
LbryID bits.Bitmap `bencode:"lbryid"`
Port int `bencode:"port"`
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}
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type storeArgs struct {
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BlobHash bits.Bitmap
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Value storeArgsValue
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NodeID bits.Bitmap // original publisher id? I think this is getting fixed in the new dht stuff
SelfStore bool // this is an int on the wire
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}
// MarshalBencode returns the serialized byte slice representation of the storage arguments.
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func (s storeArgs) MarshalBencode() ([]byte, error) {
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encodedValue, err := bencode.EncodeString(s.Value)
if err != nil {
return nil, err
}
selfStoreStr := 0
if s.SelfStore {
selfStoreStr = 1
}
return bencode.EncodeBytes([]interface{}{
s.BlobHash,
bencode.RawMessage(encodedValue),
s.NodeID,
selfStoreStr,
})
}
// UnmarshalBencode unmarshals the serialized byte slice into the appropriate fields of the store arguments.
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func (s *storeArgs) UnmarshalBencode(b []byte) error {
var argsInt []bencode.RawMessage
err := bencode.DecodeBytes(b, &argsInt)
if err != nil {
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return errors.Prefix("storeArgs unmarshal", err)
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}
if len(argsInt) != 4 {
return errors.Err("unexpected number of fields for store args. got " + cast.ToString(len(argsInt)))
}
err = bencode.DecodeBytes(argsInt[0], &s.BlobHash)
if err != nil {
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return errors.Prefix("storeArgs unmarshal", err)
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}
err = bencode.DecodeBytes(argsInt[1], &s.Value)
if err != nil {
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return errors.Prefix("storeArgs unmarshal", err)
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}
err = bencode.DecodeBytes(argsInt[2], &s.NodeID)
if err != nil {
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return errors.Prefix("storeArgs unmarshal", err)
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}
var selfStore int
err = bencode.DecodeBytes(argsInt[3], &selfStore)
if err != nil {
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return errors.Prefix("storeArgs unmarshal", err)
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}
if selfStore == 0 {
s.SelfStore = false
} else if selfStore == 1 {
s.SelfStore = true
} else {
return errors.Err("selfstore must be 1 or 0")
}
return nil
}
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// Response represents a DHT response message
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type Response struct {
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ID messageID
NodeID bits.Bitmap
Data string
Contacts []Contact
FindValueKey string
Token string
ProtocolVersion int
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}
func (r Response) argsDebug() string {
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if r.Data != "" {
return r.Data
}
str := "contacts "
if r.FindValueKey != "" {
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str = "value for " + hex.EncodeToString([]byte(r.FindValueKey))[:8] + " "
}
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str += "|"
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for _, c := range r.Contacts {
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str += c.String() + ","
}
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str = strings.TrimRight(str, ",") + "|"
if r.Token != "" {
str += " token: " + hex.EncodeToString([]byte(r.Token))[:8]
}
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return str
}
// MarshalBencode returns the serialized byte slice representation of the response.
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func (r Response) MarshalBencode() ([]byte, error) {
data := map[string]interface{}{
headerTypeField: responseType,
headerMessageIDField: r.ID,
headerNodeIDField: r.NodeID,
}
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if r.Data != "" {
// ping or store
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data[headerPayloadField] = r.Data
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} else if r.FindValueKey != "" {
// findValue success
if r.Token == "" {
return nil, errors.Err("response to findValue must have a token")
}
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var contacts [][]byte
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for _, c := range r.Contacts {
compact, err := c.MarshalCompact()
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if err != nil {
return nil, err
}
contacts = append(contacts, compact)
}
data[headerPayloadField] = map[string]interface{}{
r.FindValueKey: contacts,
tokenField: r.Token,
}
} else if r.Token != "" {
// findValue failure falling back to findNode
data[headerPayloadField] = map[string]interface{}{
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contactsField: r.Contacts,
tokenField: r.Token,
}
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} else {
// straight up findNode
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data[headerPayloadField] = r.Contacts
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}
return bencode.EncodeBytes(data)
}
// UnmarshalBencode unmarshals the serialized byte slice into the appropriate fields of the store arguments.
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func (r *Response) UnmarshalBencode(b []byte) error {
var raw struct {
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ID messageID `bencode:"1"`
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NodeID bits.Bitmap `bencode:"2"`
Data bencode.RawMessage `bencode:"3"`
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}
err := bencode.DecodeBytes(b, &raw)
if err != nil {
return err
}
r.ID = raw.ID
r.NodeID = raw.NodeID
// maybe data is a string (response to ping or store)?
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err = bencode.DecodeBytes(raw.Data, &r.Data)
if err == nil {
return nil
}
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// maybe data is a list of contacts (response to findNode)?
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err = bencode.DecodeBytes(raw.Data, &r.Contacts)
if err == nil {
return nil
}
// it must be a response to findValue
var rawData map[string]bencode.RawMessage
err = bencode.DecodeBytes(raw.Data, &rawData)
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if err != nil {
return err
}
if token, ok := rawData[tokenField]; ok {
err = bencode.DecodeBytes(token, &r.Token)
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if err != nil {
return err
}
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delete(rawData, tokenField) // so it doesnt mess up findValue key finding below
}
if protocolVersion, ok := rawData[protocolVersionField]; ok {
err = bencode.DecodeBytes(protocolVersion, &r.ProtocolVersion)
if err != nil {
return err
}
delete(rawData, protocolVersionField) // so it doesnt mess up findValue key finding below
}
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if contacts, ok := rawData[contactsField]; ok {
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err = bencode.DecodeBytes(contacts, &r.Contacts)
if err != nil {
return err
}
} else {
for k, v := range rawData {
r.FindValueKey = k
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var compactContacts [][]byte
err = bencode.DecodeBytes(v, &compactContacts)
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if err != nil {
return err
}
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for _, compact := range compactContacts {
var c Contact
err = c.UnmarshalCompact(compact)
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if err != nil {
return err
}
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r.Contacts = append(r.Contacts, c)
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}
break
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}
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}
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return nil
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}
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// Error represents a DHT error response
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type Error struct {
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ID messageID
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NodeID bits.Bitmap
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ExceptionType string
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Response []string
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}
// MarshalBencode returns the serialized byte slice representation of an error message.
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func (e Error) MarshalBencode() ([]byte, error) {
return bencode.EncodeBytes(map[string]interface{}{
headerTypeField: errorType,
headerMessageIDField: e.ID,
headerNodeIDField: e.NodeID,
headerPayloadField: e.ExceptionType,
headerArgsField: e.Response,
})
}
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// UnmarshalBencode unmarshals the serialized byte slice into the appropriate fields of the error message.
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func (e *Error) UnmarshalBencode(b []byte) error {
var raw struct {
ID messageID `bencode:"1"`
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NodeID bits.Bitmap `bencode:"2"`
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ExceptionType string `bencode:"3"`
Args interface{} `bencode:"4"`
}
err := bencode.DecodeBytes(b, &raw)
if err != nil {
return err
}
e.ID = raw.ID
e.NodeID = raw.NodeID
e.ExceptionType = raw.ExceptionType
if reflect.TypeOf(raw.Args).Kind() == reflect.Slice {
v := reflect.ValueOf(raw.Args)
for i := 0; i < v.Len(); i++ {
e.Response = append(e.Response, cast.ToString(v.Index(i).Interface()))
}
}
return nil
}