path: root/swarm/pss/client/client.go

// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// +build !noclient,!noprotocol

package client

import (
    "context"
    "errors"
    "fmt"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/common/hexutil"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/enode"
    "github.com/ethereum/go-ethereum/p2p/protocols"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/rpc"
    "github.com/ethereum/go-ethereum/swarm/log"
    "github.com/ethereum/go-ethereum/swarm/pss"
)

const (
    handshakeRetryTimeout = 1000
    handshakeRetryCount   = 3
)

// The pss client provides devp2p emulation over pss RPC API,
// giving access to pss methods from a different process
type Client struct {
    BaseAddrHex string

    // peers
    peerPool map[pss.Topic]map[string]*pssRPCRW
    protos   map[pss.Topic]*p2p.Protocol

    // rpc connections
    rpc  *rpc.Client
    subs []*rpc.ClientSubscription

    // channels
    topicsC chan []byte
    quitC   chan struct{}

    poolMu sync.Mutex
}

// implements p2p.MsgReadWriter
type pssRPCRW struct {
    *Client
    topic    string
    msgC     chan []byte
    addr     pss.PssAddress
    pubKeyId string
    lastSeen time.Time
    closed   bool
}

func (c *Client) newpssRPCRW(pubkeyid string, addr pss.PssAddress, topicobj pss.Topic) (*pssRPCRW, error) {
    topic := topicobj.String()
    err := c.rpc.Call(nil, "pss_setPeerPublicKey", pubkeyid, topic, hexutil.Encode(addr[:]))
    if err != nil {
        return nil, fmt.Errorf("setpeer %s %s: %v", topic, pubkeyid, err)
    }
    return &pssRPCRW{
        Client:   c,
        topic:    topic,
        msgC:     make(chan []byte),
        addr:     addr,
        pubKeyId: pubkeyid,
    }, nil
}

func (rw *pssRPCRW) ReadMsg() (p2p.Msg, error) {
    msg := <-rw.msgC
    log.Trace("pssrpcrw read", "msg", msg)
    pmsg, err := pss.ToP2pMsg(msg)
    if err != nil {
        return p2p.Msg{}, err
    }

    return pmsg, nil
}

// If only one message slot left
// then new is requested through handshake
// if buffer is empty, handshake request blocks until return
// after which pointer is changed to first new key in buffer
// will fail if:
// - any api calls fail
// - handshake retries are exhausted without reply,
// - send fails
func (rw *pssRPCRW) WriteMsg(msg p2p.Msg) error {
    log.Trace("got writemsg pssclient", "msg", msg)
    if rw.closed {
        return fmt.Errorf("connection closed")
    }
    rlpdata := make([]byte, msg.Size)
    msg.Payload.Read(rlpdata)
    pmsg, err := rlp.EncodeToBytes(pss.ProtocolMsg{
        Code:    msg.Code,
        Size:    msg.Size,
        Payload: rlpdata,
    })
    if err != nil {
        return err
    }

    // Get the keys we have
    var symkeyids []string
    err = rw.Client.rpc.Call(&symkeyids, "pss_getHandshakeKeys", rw.pubKeyId, rw.topic, false, true)
    if err != nil {
        return err
    }

    // Check the capacity of the first key
    var symkeycap uint16
    if len(symkeyids) > 0 {
        err = rw.Client.rpc.Call(&symkeycap, "pss_getHandshakeKeyCapacity", symkeyids[0])
        if err != nil {
            return err
        }
    }

    err = rw.Client.rpc.Call(nil, "pss_sendSym", symkeyids[0], rw.topic, hexutil.Encode(pmsg))
    if err != nil {
        return err
    }

    // If this is the last message it is valid for, initiate new handshake
    if symkeycap == 1 {
        var retries int
        var sync bool
        // if it's the only remaining key, make sure we don't continue until we have new ones for further writes
        if len(symkeyids) == 1 {
            sync = true
        }
        // initiate handshake
        _, err := rw.handshake(retries, sync, false)
        if err != nil {
            log.Warn("failing", "err", err)
            return err
        }
    }
    return nil
}

// retry and synchronicity wrapper for handshake api call
// returns first new symkeyid upon successful execution
func (rw *pssRPCRW) handshake(retries int, sync bool, flush bool) (string, error) {

    var symkeyids []string
    var i int
    // request new keys
    // if the key buffer was depleted, make this as a blocking call and try several times before giving up
    for i = 0; i < 1+retries; i++ {
        log.Debug("handshake attempt pssrpcrw", "pubkeyid", rw.pubKeyId, "topic", rw.topic, "sync", sync)
        err := rw.Client.rpc.Call(&symkeyids, "pss_handshake", rw.pubKeyId, rw.topic, sync, flush)
        if err == nil {
            var keyid string
            if sync {
                keyid = symkeyids[0]
            }
            return keyid, nil
        }
        if i-1+retries > 1 {
            time.Sleep(time.Millisecond * handshakeRetryTimeout)
        }
    }

    return "", fmt.Errorf("handshake failed after %d attempts", i)
}

// Custom constructor
//
// Provides direct access to the rpc object
func NewClient(rpcurl string) (*Client, error) {
    rpcclient, err := rpc.Dial(rpcurl)
    if err != nil {
        return nil, err
    }

    client, err := NewClientWithRPC(rpcclient)
    if err != nil {
        return nil, err
    }
    return client, nil
}

// Main constructor
//
// The 'rpcclient' parameter allows passing a in-memory rpc client to act as the remote websocket RPC.
func NewClientWithRPC(rpcclient *rpc.Client) (*Client, error) {
    client := newClient()
    client.rpc = rpcclient
    err := client.rpc.Call(&client.BaseAddrHex, "pss_baseAddr")
    if err != nil {
        return nil, fmt.Errorf("cannot get pss node baseaddress: %v", err)
    }
    return client, nil
}

func newClient() (client *Client) {
    client = &Client{
        quitC:    make(chan struct{}),
        peerPool: make(map[pss.Topic]map[string]*pssRPCRW),
        protos:   make(map[pss.Topic]*p2p.Protocol),
    }
    return
}

// Mounts a new devp2p protcool on the pss connection
//
// the protocol is aliased as a "pss topic"
// uses normal devp2p send and incoming message handler routines from the p2p/protocols package
//
// when an incoming message is received from a peer that is not yet known to the client,
// this peer object is instantiated, and the protocol is run on it.
func (c *Client) RunProtocol(ctx context.Context, proto *p2p.Protocol) error {
    topicobj := pss.BytesToTopic([]byte(fmt.Sprintf("%s:%d", proto.Name, proto.Version)))
    topichex := topicobj.String()
    msgC := make(chan pss.APIMsg)
    c.peerPool[topicobj] = make(map[string]*pssRPCRW)
    sub, err := c.rpc.Subscribe(ctx, "pss", msgC, "receive", topichex)
    if err != nil {
        return fmt.Errorf("pss event subscription failed: %v", err)
    }
    c.subs = append(c.subs, sub)
    err = c.rpc.Call(nil, "pss_addHandshake", topichex)
    if err != nil {
        return fmt.Errorf("pss handshake activation failed: %v", err)
    }

    // dispatch incoming messages
    go func() {
        for {
            select {
            case msg := <-msgC:
                // we only allow sym msgs here
                if msg.Asymmetric {
                    continue
                }
                // we get passed the symkeyid
                // need the symkey itself to resolve to peer's pubkey
                var pubkeyid string
                err = c.rpc.Call(&pubkeyid, "pss_getHandshakePublicKey", msg.Key)
                if err != nil || pubkeyid == "" {
                    log.Trace("proto err or no pubkey", "err", err, "symkeyid", msg.Key)
                    continue
                }
                // if we don't have the peer on this protocol already, create it
                // this is more or less the same as AddPssPeer, less the handshake initiation
                if c.peerPool[topicobj][pubkeyid] == nil {
                    var addrhex string
                    err := c.rpc.Call(&addrhex, "pss_getAddress", topichex, false, msg.Key)
                    if err != nil {
                        log.Trace(err.Error())
                        continue
                    }
                    addrbytes, err := hexutil.Decode(addrhex)
                    if err != nil {
                        log.Trace(err.Error())
                        break
                    }
                    addr := pss.PssAddress(addrbytes)
                    rw, err := c.newpssRPCRW(pubkeyid, addr, topicobj)
                    if err != nil {
                        break
                    }
                    c.peerPool[topicobj][pubkeyid] = rw
                    p := p2p.NewPeer(enode.ID{}, fmt.Sprintf("%v", addr), []p2p.Cap{})
                    go proto.Run(p, c.peerPool[topicobj][pubkeyid])
                }
                go func() {
                    c.peerPool[topicobj][pubkeyid].msgC <- msg.Msg
                }()
            case <-c.quitC:
                return
            }
        }
    }()

    c.protos[topicobj] = proto
    return nil
}

// Always call this to ensure that we exit cleanly
func (c *Client) Close() error {
    for _, s := range c.subs {
        s.Unsubscribe()
    }
    return nil
}

// Add a pss peer (public key) and run the protocol on it
//
// client.RunProtocol with matching topic must have been
// run prior to adding the peer, or this method will
// return an error.
//
// The key must exist in the key store of the pss node
// before the peer is added. The method will return an error
// if it is not.
func (c *Client) AddPssPeer(pubkeyid string, addr []byte, spec *protocols.Spec) error {
    topic := pss.ProtocolTopic(spec)
    if c.peerPool[topic] == nil {
        return errors.New("addpeer on unset topic")
    }
    if c.peerPool[topic][pubkeyid] == nil {
        rw, err := c.newpssRPCRW(pubkeyid, addr, topic)
        if err != nil {
            return err
        }
        _, err = rw.handshake(handshakeRetryCount, true, true)
        if err != nil {
            return err
        }
        c.poolMu.Lock()
        c.peerPool[topic][pubkeyid] = rw
        c.poolMu.Unlock()
        p := p2p.NewPeer(enode.ID{}, fmt.Sprintf("%v", addr), []p2p.Cap{})
        go c.protos[topic].Run(p, c.peerPool[topic][pubkeyid])
    }
    return nil
}

// Remove a pss peer
//
// TODO: underlying cleanup
func (c *Client) RemovePssPeer(pubkeyid string, spec *protocols.Spec) {
    log.Debug("closing pss client peer", "pubkey", pubkeyid, "protoname", spec.Name, "protoversion", spec.Version)
    c.poolMu.Lock()
    defer c.poolMu.Unlock()
    topic := pss.ProtocolTopic(spec)
    c.peerPool[topic][pubkeyid].closed = true
    delete(c.peerPool[topic], pubkeyid)
}