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dht logic for retrieval request handling

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zelig 2015-02-04 22:46:25 +01:00
parent 827ef3e111
commit 0da3b36175
3 changed files with 268 additions and 120 deletions
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176
bzz/hive.go
View file

@ -1,9 +1,177 @@
package bzz
import ()
/*
TODO:
- put Data -> Reader logic to chunker
- clarify dpa / hive / netstore naming and division of labour and entry points for local/remote requests
- figure out if its a problem that peers on requester list may disconnect while searching
- Id (nonce/requester map key) should probs be random byte slice or (hash of) originator's address to avoid collisions
- rework protocol errors using errs after PR merged
- integrate cademlia as peer pool
- finish the net/dht logic, startSearch and storage
*/
import (
"sync"
"time"
)
type Hive struct {
dpa *DPA
memstore *memStore
lock sync.Mutex
}
/*
Hive is the logistic manager at swarm
It is based on kademlia wisdom and flexible forwarding policies for optimal network health.
Hive implements the PeerPool interface (Thx fjl) and as such plays a role in how peers are selected by the p2p server. Ideally the p2p server regularly polls the registered protocol peer pools for good peers (an ordered wishlist of peers to connect to) and chooses the best one not connected. The Bzz Hive is therefore keeping a persistent record of peers for reputation and proximity considerations (or any other indirect incentive maybe).
request status values:
- blank
- started searching
- timed out
- found
*/
const (
reqBlank = iota
reqSearching
reqTimedOut
reqFound
)
const requesterCount = 3
type peer struct {
*bzzProtocol
}
type requestStatus struct {
key Key
status int
requesters map[uint64][]*retrieveRequestMsgData
}
// it's assumed that caller holds the lock
func (self *Hive) startSearch(chunk *Chunk) {
chunk.req.status = reqSearching
// implement search logic here
}
/*
adds a new peer to an existing open request
only add if less than requesterCount peers forwarded the same request id so far
note this is done irrespective of status (searching or found/timedOut)
*/
func (self *Hive) addRequester(rs *requestStatus, req *retrieveRequestMsgData) (added bool) {
list := rs.requesters[req.Id]
if len(list) < requesterCount {
rs.requesters[req.Id] = append(list, req)
added = true
}
return
}
/*
decides how to respond to a retrieval request
updates the request status if needed
returns
send bool: true if chunk is to be delivered, false if respond with peers (as for now)
timeout: if respond with peers, timeout indicates our bet
this is the most simplistic implementation:
- respond with delivery iff less than requesterCount peers forwarded the same request id so far and chunk is found
- respond with reject (peers and zero timeout) if given up
- respond with peers and timeout if still searching
! in the last case as well, we should respond with reject if already got requesterCount peers with that exact id
*/
func (self *Hive) strategyUpdateRequest(rs *requestStatus, req *retrieveRequestMsgData) (send bool, timeout time.Time) {
switch rs.status {
case reqSearching:
self.addRequester(rs, req)
timeout = self.searchTimeout(rs, req)
case reqTimedOut:
case reqFound:
if self.addRequester(rs, req) {
send = true
} else {
// timeout = time.Time(0)
}
}
return
}
func (self *Hive) addStoreRequest(req *storeRequestMsgData) (err error) {
self.lock.Lock()
defer self.lock.Unlock()
// TODO:
return
}
func (self *Hive) addRetrieveRequest(req *retrieveRequestMsgData) {
self.lock.Lock()
defer self.lock.Unlock()
chunk, err := self.dpa.Get(req.Key)
// we assume that a returned chunk is the one stored in the memory cache
if err != nil {
// no data and no request status
chunk = &Chunk{
Key: req.Key,
}
self.memstore.Put(chunk)
}
if chunk.req == nil {
chunk.req = new(requestStatus)
if chunk.Data == nil {
self.startSearch(chunk)
}
}
send, timeout := self.strategyUpdateRequest(chunk.req, req) // may change req status
if send {
self.deliver(req, chunk)
} else {
// we might need chunk.req to cache relevant peers response, or would it expire?
self.peers(req, chunk, timeout)
}
}
func (self *Hive) deliver(req *retrieveRequestMsgData, chunk *Chunk) {
storeReq := &storeRequestMsgData{
Key: req.Key,
Id: req.Id,
Data: chunk.Data,
Size: chunk.Size,
RequestTimeout: req.Timeout, //
// StorageTimeout time.Time // expiry of content
// Metadata metaData
}
req.peer.store(storeReq)
}
func (self *Hive) peers(req *retrieveRequestMsgData, chunk *Chunk, timeout time.Time) {
peersData := &peersMsgData{
Peers: []*peerAddr{}, // get proximity bin from cademlia routing table
Key: req.Key,
Id: req.Id,
Timeout: timeout,
}
req.peer.peers(peersData)
}
func (self *Hive) searchTimeout(rs *requestStatus, req *retrieveRequestMsgData) (timeout time.Time) {
return
}
// these should go to cademlia
func (self *Hive) addPeers(req *peersMsgData) (err error) {
return
}
func (self *Hive) removePeer(p peer) {
return
}

2
bzz/netstore.go
View file

@ -6,5 +6,5 @@ It accumulates requests from peers, keeping a request pool and does forwarding f
*/
// it implements the ChunkStore interface
type DHTStore struct {
type netStore struct {
}

210
bzz/protocol.go
View file

@ -2,12 +2,12 @@ package bzz
/*
BZZ implements the bzz wire protocol of swarm
routing decoded storage and retrieval requests to DPA
and registering peers with the DHT
routing decoded storage and retrieval requests
registering peers with the DHT
*/
import (
"fmt"
"net"
"time"
"github.com/ethereum/go-ethereum/p2p"
@ -23,30 +23,17 @@ const (
// bzz protocol message codes
const (
StatusMsg = iota // 0x01
StoreRequestMsg // 0x02
RetrieveRequestMsg // 0x03
GetBlockHashesMsg // 0x04
PeersMsg // 0x05
DeliveryMsg // 0x06
statusMsg = iota // 0x01
storeRequestMsg // 0x02
retrieveRequestMsg // 0x03
peersMsg // 0x04
)
type BzzHive interface {
AddStoreRequest(*StoreRequestMsgData, *p2p.Peer) error
AddRetrieveRequest(*RetrieveRequestMsgData, *p2p.Peer) error
AddPeers([]*p2p.Peer) error
AddDelivery(*DeliveryMsgData, *p2p.Peer) error
RemovePeer(*p2p.Peer)
}
// bzzProtocol represents the swarm wire protocol
// instance is running on each peer
type bzzProtocol struct {
Hive BzzHive
DHT *DHTStore
// CAD *p2p.Cademlia
hive *Hive
peer *p2p.Peer
id string
rw p2p.MsgReadWriter
}
@ -68,18 +55,15 @@ Peers
[0x04, key: B_256, timeout: B_64, peers: [[peer], [peer], .... ]] the encoding of a peer is identical to that in the devp2p base protocol peers messages: [IP, Port, NodeID] note that a node's DPA address is not the NodeID but the hash of the NodeID. Timeout serves to indicate whether the responder is forwarding the query within the timeout or not.
Delivery
[0x05, key: B_256, metadata: [], data: B_4k]: the delivery response to retrieval queries.
*/
type StatusMsgData struct {
type statusMsgData struct {
Version uint64
ID string
NodeID []byte
NetworkId uint64
Caps []p2p.Cap
Strategy uint64
// Strategy uint64
}
/*
@ -88,15 +72,17 @@ type StatusMsgData struct {
if they are within our storage radius or have any incentive to store it then attach your nodeID to the metadata
if the storage request is sufficiently close (within our proximity range (the last row of the routing table), then sending it to all peers will not guarantee convergence, so there needs to be an absolute expiry of the request too. Maybe the protocol should specify a forward probability exponentially declining with age.
*/
type StoreRequestMsgData struct {
Key Key // hash of datasize | data
Size uint64 // size of data in bytes
Data []byte // is this needed?
Reader SectionReader // is the underlying byte slice already buffered within the app somewhere?
type storeRequestMsgData struct {
Key Key // hash of datasize | data
Size int64 // size of data in bytes
Data []byte // is this needed?
// optional
Id uint64 //
RequestTimeout time.Time // expiry for forwarding
StorageTimeout time.Time // expiry of content
Metadata MetaData
Metadata metaData //
//
peer peer
}
/*
@ -106,75 +92,79 @@ MaxSize specifies the maximum size that the peer will accept. This is useful in
In the special case that the key is identical to the peers own address (hash of NodeID) the message is to be handled as a self lookup. The response is a PeersMsg with the peers in the cademlia proximity bin corresponding to the address.
It is unclear if a retrieval request with an empty target is the same as a self lookup
*/
type RetrieveRequestMsgData struct {
Key Key
MaxSize uint64 // optional maximum size of delivery accepted
Timeout time.Time //optional, if missing or
Metadata MetaData
type retrieveRequestMsgData struct {
Key Key
// optional
Id uint64 //
MaxSize int64 // maximum size of delivery accepted
Timeout time.Time //
Metadata metaData //
//
peer peer
}
/* one response to retrieval, always encouraged after a retrieval request to respond with a list of peers in the same cademlia proximity bin.
type peerAddr struct {
IP net.IP
Port uint64
Pubkey []byte
}
/*
one response to retrieval, always encouraged after a retrieval request to respond with a list of peers in the same cademlia proximity bin.
The encoding of a peer is identical to that in the devp2p base protocol peers messages: [IP, Port, NodeID]
note that a node's DPA address is not the NodeID but the hash of the NodeID.
Timeout serves to indicate whether the responder is forwarding the query within the timeout or not.
The Key is the target (if response to a retrieval request) or peers address (hash of NodeID) if retrieval request was a self lookup.
It is unclear if PeersMsg with an empty Key has a special meaning or just mean the same as with the peers address as Key (cademlia bin)
*/
type PeersMsgData struct {
Peers []*p2p.Peer
Key Key // if a response to a retrieval request
type peersMsgData struct {
Peers []*peerAddr //
Timeout time.Time // indicate whether responder is expected to deliver content
Key Key // if a response to a retrieval request
Id uint64 // if a response to a retrieval request
//
peer peer
}
/*
Delivery and storeRequest messages could be lumped together or maybe distinguished by their request timeout ?
metadata is as yet a placeholder
it will likely contain info about hops or the entire forward chain of node IDs
this may allow some interesting schemes to evolve optimal routing strategies
metadata for storage and retrieval requests could specify format parameters relevant for the (blockhashing) chunking scheme used (for chunks corresponding to a treenode). For instance all runtime params for the chunker (hashing algorithm used, branching etc.)
Finally metadata can hold info relevant to some reward or compensation scheme that may be used to incentivise peers.
*/
// wonder if we should use Chunk here directly or keep loosely coupled
type DeliveryMsgData struct {
Key Key
Data SectionReader
Metadata MetaData
}
type metaData struct{}
/*
metadata is as yet a placeholder
it will likely contain info about hops or the entire forward chain of node IDs
this may allow some interesting schemes to evolve optimal routing strategies
metadata for storage and retrieval requests could specify format parameters relevant for the (blockhashing) chunking scheme used (for chunks corresponding to a treenode). For instance all runtime params for the chunker (hashing algorithm used, branching etc.)
Finally metadata can hold info relevant to some reward or compensation scheme that may be used to incentivise peers.
main entrypoint, wrappers starting a server running the bzz protocol
use this constructor to attach the protocol ("class") to server caps
the Dev p2p layer then runs the protocol instance on each peer
*/
type MetaData struct{}
// main entrypoint, wrappers starting a server running the bzz protocol
// use this constructor to attach the protocol ("class") to server caps
// the Dev p2p layer then runs the protocol instance on each peer
func BzzProtocol(hive BzzHive) p2p.Protocol {
func BzzProtocol(hive *Hive) p2p.Protocol {
return p2p.Protocol{
Name: "bzz",
Version: Version,
Length: ProtocolLength,
Run: func(peer *p2p.Peer, rw p2p.MsgReadWriter) error {
return runBzzProtocol(hive, peer, rw)
Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
return runBzzProtocol(hive, p, rw)
},
}
}
// the main loop that handles incoming messages
// note RemovePeer in the post-disconnect hook
func runBzzProtocol(hive BzzHive, peer *p2p.Peer, rw p2p.MsgReadWriter) (err error) {
func runBzzProtocol(hive *Hive, p *p2p.Peer, rw p2p.MsgReadWriter) (err error) {
self := &bzzProtocol{
Hive: hive,
// DHT: dht,
// CAD: cad,
hive: hive,
rw: rw,
peer: peer,
id: fmt.Sprintf("%x", peer.Identity().Pubkey()[:8]),
peer: p,
}
err = self.handleStatus()
if err == nil {
for {
err = self.handle()
if err != nil {
self.Hive.RemovePeer(self.peer)
self.hive.removePeer(peer{self})
break
}
}
@ -193,43 +183,38 @@ func (self *bzzProtocol) handle() error {
// make sure that the payload has been fully consumed
defer msg.Discard()
/*
StatusMsg = iota // 0x01
StoreRequestMsg // 0x02
RetrieveRequestMsg // 0x03
PeersMsg // 0x04
DeliveryMsg // 0x05
statusMsg = iota // 0x01
storeRequestMsg // 0x02
retrieveRequestMsg // 0x03
peersMsg // 0x04
*/
switch msg.Code {
case StatusMsg:
case statusMsg:
return self.protoError(ErrExtraStatusMsg, "")
case StoreRequestMsg:
var req StoreRequestMsgData
case storeRequestMsg:
var req storeRequestMsgData
if err := msg.Decode(&req); err != nil {
return self.protoError(ErrDecode, "msg %v: %v", msg, err)
}
self.Hive.AddStoreRequest(&req, self.peer)
req.peer = peer{self}
self.hive.addStoreRequest(&req)
case RetrieveRequestMsg:
var req RetrieveRequestMsgData
case retrieveRequestMsg:
var req retrieveRequestMsgData
if err := msg.Decode(&req); err != nil {
return self.protoError(ErrDecode, "->msg %v: %v", msg, err)
}
self.Hive.AddRetrieveRequest(&req, self.peer)
req.peer = peer{self}
self.hive.addRetrieveRequest(&req)
case PeersMsg:
var req PeersMsgData
case peersMsg:
var req peersMsgData
if err := msg.Decode(&req); err != nil {
return self.protoError(ErrDecode, "->msg %v: %v", msg, err)
}
self.Hive.AddPeers(req.Peers)
case DeliveryMsg:
var req DeliveryMsgData
if err := msg.Decode(&req); err != nil {
return self.protoError(ErrDecode, "->msg %v: %v", msg, err)
}
self.Hive.AddDelivery(&req, self.peer)
req.peer = peer{self}
self.hive.addPeers(&req)
default:
return self.protoError(ErrInvalidMsgCode, "%v", msg.Code)
@ -237,19 +222,9 @@ func (self *bzzProtocol) handle() error {
return nil
}
/*
type StatusMsg struct {
Version uint64
ID string
NodeID []byte
Caps []Cap
Strategy uint64
}
*/
func (self *bzzProtocol) statusMsg() p2p.Msg {
return p2p.NewMsg(StatusMsg,
return p2p.NewMsg(statusMsg,
uint32(Version),
uint32(NetworkId),
"honey",
@ -270,15 +245,15 @@ func (self *bzzProtocol) handleStatus() error {
return err
}
if msg.Code != StatusMsg {
return self.protoError(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
if msg.Code != statusMsg {
return self.protoError(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, statusMsg)
}
if msg.Size > ProtocolMaxMsgSize {
return self.protoError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
}
var status StatusMsgData
var status statusMsgData
if err := msg.Decode(&status); err != nil {
return self.protoError(ErrDecode, "msg %v: %v", msg, err)
}
@ -293,27 +268,32 @@ func (self *bzzProtocol) handleStatus() error {
self.peer.Infof("Peer is [bzz] capable (%d/%d)\n", status.Version, status.NetworkId)
self.Hive.AddPeers([]*p2p.Peer{self.peer})
req := &peersMsgData{
// Peers: []*peerAddr{self.peer.Address()}, // not implemented in p2p, should be the same as node discovery cademlia
// Key: nil,
peer: peer{self},
}
self.hive.addPeers(req)
return nil
}
func (self *bzzProtocol) Retrieve(req RetrieveRequestMsgData) error {
return p2p.EncodeMsg(self.rw, RetrieveRequestMsg, req)
// outgoing messages
func (self *bzzProtocol) retrieve(req *retrieveRequestMsgData) {
p2p.EncodeMsg(self.rw, retrieveRequestMsg, req)
}
func (self *bzzProtocol) Store(req StoreRequestMsgData) error {
return p2p.EncodeMsg(self.rw, StoreRequestMsg, req)
func (self *bzzProtocol) store(req *storeRequestMsgData) {
p2p.EncodeMsg(self.rw, storeRequestMsg, req)
}
func (self *bzzProtocol) DeliveryMsg(req DeliveryMsgData) error {
return p2p.EncodeMsg(self.rw, DeliveryMsg, req)
}
func (self *bzzProtocol) Peers(req PeersMsgData) error {
return p2p.EncodeMsg(self.rw, PeersMsg, req)
func (self *bzzProtocol) peers(req *peersMsgData) {
p2p.EncodeMsg(self.rw, peersMsg, req)
}
// errors
// TODO: should be reworked using errs pkg
func (self *bzzProtocol) protoError(code int, format string, params ...interface{}) (err *protocolError) {
err = ProtocolError(code, format, params...)
if err.Fatal() {