path: root/swarm/pss/protocol.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 !nopssprotocol

package pss

import (
    "bytes"
    "fmt"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/protocols"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/swarm/log"
)

const (
    IsActiveProtocol = true
)

// Convenience wrapper for devp2p protocol messages for transport over pss
type ProtocolMsg struct {
    Code       uint64
    Size       uint32
    Payload    []byte
    ReceivedAt time.Time
}

// Creates a ProtocolMsg
func NewProtocolMsg(code uint64, msg interface{}) ([]byte, error) {

    rlpdata, err := rlp.EncodeToBytes(msg)
    if err != nil {
        return nil, err
    }

    // TODO verify that nested structs cannot be used in rlp
    smsg := &ProtocolMsg{
        Code:    code,
        Size:    uint32(len(rlpdata)),
        Payload: rlpdata,
    }

    return rlp.EncodeToBytes(smsg)
}

// Protocol options to be passed to a new Protocol instance
//
// The parameters specify which encryption schemes to allow
type ProtocolParams struct {
    Asymmetric bool
    Symmetric  bool
}

// PssReadWriter bridges pss send/receive with devp2p protocol send/receive
//
// Implements p2p.MsgReadWriter
type PssReadWriter struct {
    *Pss
    LastActive time.Time
    rw         chan p2p.Msg
    spec       *protocols.Spec
    topic      *Topic
    sendFunc   func(string, Topic, []byte) error
    key        string
    closed     bool
}

// Implements p2p.MsgReader
func (prw *PssReadWriter) ReadMsg() (p2p.Msg, error) {
    msg := <-prw.rw
    log.Trace(fmt.Sprintf("pssrw readmsg: %v", msg))
    return msg, nil
}

// Implements p2p.MsgWriter
func (prw *PssReadWriter) WriteMsg(msg p2p.Msg) error {
    log.Trace("pssrw writemsg", "msg", msg)
    if prw.closed {
        return fmt.Errorf("connection closed")
    }
    rlpdata := make([]byte, msg.Size)
    msg.Payload.Read(rlpdata)
    pmsg, err := rlp.EncodeToBytes(ProtocolMsg{
        Code:    msg.Code,
        Size:    msg.Size,
        Payload: rlpdata,
    })
    if err != nil {
        return err
    }
    return prw.sendFunc(prw.key, *prw.topic, pmsg)
}

// Injects a p2p.Msg into the MsgReadWriter, so that it appears on the associated p2p.MsgReader
func (prw *PssReadWriter) injectMsg(msg p2p.Msg) error {
    log.Trace(fmt.Sprintf("pssrw injectmsg: %v", msg))
    prw.rw <- msg
    return nil
}

// Convenience object for emulation devp2p over pss
type Protocol struct {
    *Pss
    proto        *p2p.Protocol
    topic        *Topic
    spec         *protocols.Spec
    pubKeyRWPool map[string]p2p.MsgReadWriter
    symKeyRWPool map[string]p2p.MsgReadWriter
    Asymmetric   bool
    Symmetric    bool
    RWPoolMu     sync.Mutex
}

// Activates devp2p emulation over a specific pss topic
//
// One or both encryption schemes must be specified. If
// only one is specified, the protocol will not be valid
// for the other, and will make the message handler
// return errors
func RegisterProtocol(ps *Pss, topic *Topic, spec *protocols.Spec, targetprotocol *p2p.Protocol, options *ProtocolParams) (*Protocol, error) {
    if !options.Asymmetric && !options.Symmetric {
        return nil, fmt.Errorf("specify at least one of asymmetric or symmetric messaging mode")
    }
    pp := &Protocol{
        Pss:          ps,
        proto:        targetprotocol,
        topic:        topic,
        spec:         spec,
        pubKeyRWPool: make(map[string]p2p.MsgReadWriter),
        symKeyRWPool: make(map[string]p2p.MsgReadWriter),
        Asymmetric:   options.Asymmetric,
        Symmetric:    options.Symmetric,
    }
    return pp, nil
}

// Generic handler for incoming messages over devp2p emulation
//
// To be passed to pss.Register()
//
// Will run the protocol on a new incoming peer, provided that
// the encryption key of the message has a match in the internal
// pss keypool
//
// Fails if protocol is not valid for the message encryption scheme,
// if adding a new peer fails, or if the message is not a serialized
// p2p.Msg (which it always will be if it is sent from this object).
func (p *Protocol) Handle(msg []byte, peer *p2p.Peer, asymmetric bool, keyid string) error {
    var vrw *PssReadWriter
    if p.Asymmetric != asymmetric && p.Symmetric == !asymmetric {
        return fmt.Errorf("invalid protocol encryption")
    } else if (!p.isActiveSymKey(keyid, *p.topic) && !asymmetric) ||
        (!p.isActiveAsymKey(keyid, *p.topic) && asymmetric) {

        rw, err := p.AddPeer(peer, *p.topic, asymmetric, keyid)
        if err != nil {
            return err
        }
        vrw = rw.(*PssReadWriter)
    }

    pmsg, err := ToP2pMsg(msg)
    if err != nil {
        return fmt.Errorf("could not decode pssmsg")
    }
    if asymmetric {
        vrw = p.pubKeyRWPool[keyid].(*PssReadWriter)
    } else {
        vrw = p.symKeyRWPool[keyid].(*PssReadWriter)
    }
    vrw.injectMsg(pmsg)
    return nil
}

// check if (peer) symmetric key is currently registered with this topic
func (p *Protocol) isActiveSymKey(key string, topic Topic) bool {
    return p.symKeyRWPool[key] != nil
}

// check if (peer) asymmetric key is currently registered with this topic
func (p *Protocol) isActiveAsymKey(key string, topic Topic) bool {
    return p.pubKeyRWPool[key] != nil
}

// Creates a serialized (non-buffered) version of a p2p.Msg, used in the specialized internal p2p.MsgReadwriter implementations
func ToP2pMsg(msg []byte) (p2p.Msg, error) {
    payload := &ProtocolMsg{}
    if err := rlp.DecodeBytes(msg, payload); err != nil {
        return p2p.Msg{}, fmt.Errorf("pss protocol handler unable to decode payload as p2p message: %v", err)
    }

    return p2p.Msg{
        Code:       payload.Code,
        Size:       uint32(len(payload.Payload)),
        ReceivedAt: time.Now(),
        Payload:    bytes.NewBuffer(payload.Payload),
    }, nil
}

// Runs an emulated pss Protocol on the specified peer,
// linked to a specific topic
// `key` and `asymmetric` specifies what encryption key
// to link the peer to.
// The key must exist in the pss store prior to adding the peer.
func (p *Protocol) AddPeer(peer *p2p.Peer, topic Topic, asymmetric bool, key string) (p2p.MsgReadWriter, error) {
    rw := &PssReadWriter{
        Pss:   p.Pss,
        rw:    make(chan p2p.Msg),
        spec:  p.spec,
        topic: p.topic,
        key:   key,
    }
    if asymmetric {
        rw.sendFunc = p.Pss.SendAsym
    } else {
        rw.sendFunc = p.Pss.SendSym
    }
    if asymmetric {
        p.Pss.pubKeyPoolMu.Lock()
        if _, ok := p.Pss.pubKeyPool[key]; !ok {
            return nil, fmt.Errorf("asym key does not exist: %s", key)
        }
        p.Pss.pubKeyPoolMu.Unlock()
        p.RWPoolMu.Lock()
        p.pubKeyRWPool[key] = rw
        p.RWPoolMu.Unlock()
    } else {
        p.Pss.symKeyPoolMu.Lock()
        if _, ok := p.Pss.symKeyPool[key]; !ok {
            return nil, fmt.Errorf("symkey does not exist: %s", key)
        }
        p.Pss.symKeyPoolMu.Unlock()
        p.RWPoolMu.Lock()
        p.symKeyRWPool[key] = rw
        p.RWPoolMu.Unlock()
    }
    go func() {
        err := p.proto.Run(peer, rw)
        log.Warn(fmt.Sprintf("pss vprotocol quit on %v topic %v: %v", peer, topic, err))
    }()
    return rw, nil
}

func (p *Protocol) RemovePeer(asymmetric bool, key string) {
    log.Debug("closing pss peer", "asym", asymmetric, "key", key)
    p.RWPoolMu.Lock()
    defer p.RWPoolMu.Unlock()
    if asymmetric {
        rw := p.pubKeyRWPool[key].(*PssReadWriter)
        rw.closed = true
        delete(p.pubKeyRWPool, key)
    } else {
        rw := p.symKeyRWPool[key].(*PssReadWriter)
        rw.closed = true
        delete(p.symKeyRWPool, key)
    }
}

// Uniform translation of protocol specifiers to topic
func ProtocolTopic(spec *protocols.Spec) Topic {
    return BytesToTopic([]byte(fmt.Sprintf("%s:%d", spec.Name, spec.Version)))
}