cwtch/peer/send/peer_send_channel.go

package send

import (
	"cwtch.im/cwtch/protocol"
	"cwtch.im/cwtch/protocol/spam"
	"errors"
	"git.openprivacy.ca/openprivacy/libricochet-go/channels"
	"git.openprivacy.ca/openprivacy/libricochet-go/utils"
	"git.openprivacy.ca/openprivacy/libricochet-go/wire/control"
	"github.com/golang/protobuf/proto"
)

// CwtchPeerSendChannel is the peer implementation of im.cwtch.server.send
type CwtchPeerSendChannel struct {
	channel   *channels.Channel
	spamGuard spam.Guard
	challenge []byte
}

// Type returns the type string for this channel, e.g. "im.ricochet.server.send".
func (cpsc *CwtchPeerSendChannel) Type() string {
	return "im.cwtch.server.send"
}

// Closed is called when the channel is closed for any reason.
func (cpsc *CwtchPeerSendChannel) Closed(err error) {

}

// OnlyClientCanOpen  - for Cwtch server channels only peers may open.
func (cpsc *CwtchPeerSendChannel) OnlyClientCanOpen() bool {
	return true
}

// Singleton - for Cwtch channels there can only be one instance per direction
func (cpsc *CwtchPeerSendChannel) Singleton() bool {
	return true
}

// Bidirectional - for Cwtch channels are not bidrectional
func (cpsc *CwtchPeerSendChannel) Bidirectional() bool {
	return false
}

// RequiresAuthentication - Cwtch channels require no auth
func (cpsc *CwtchPeerSendChannel) RequiresAuthentication() string {
	return "none"
}

// OpenInbound should never be called on peers.
func (cpsc *CwtchPeerSendChannel) OpenInbound(channel *channels.Channel, raw *Protocol_Data_Control.OpenChannel) ([]byte, error) {
	return nil, errors.New("client does not receive inbound listen channels")
}

// OpenOutbound is used to set up a new send channel and initialize spamguard
func (cpsc *CwtchPeerSendChannel) OpenOutbound(channel *channels.Channel) ([]byte, error) {
	cpsc.spamGuard.Difficulty = 2
	cpsc.channel = channel
	messageBuilder := new(utils.MessageBuilder)
	return messageBuilder.OpenChannel(channel.ID, cpsc.Type()), nil
}

// OpenOutboundResult confirms the open channel request and sets the spamguard challenge
func (cpsc *CwtchPeerSendChannel) OpenOutboundResult(err error, crm *Protocol_Data_Control.ChannelResult) {
	if err == nil {
		if crm.GetOpened() {
			cpsc.channel.Pending = false
			ce, _ := proto.GetExtension(crm, protocol.E_ServerNonce)
			cpsc.challenge = ce.([]byte)[:]

		}
	}
}

// SendGroupMessage performs the spamguard proof of work and sends a message.
func (cpsc *CwtchPeerSendChannel) SendGroupMessage(gm *protocol.GroupMessage) error {
	if cpsc.channel.Pending == false {
		sgsolve := cpsc.spamGuard.SolveChallenge(cpsc.challenge, gm.GetCiphertext())
		gm.Spamguard = sgsolve[:]
		csp := &protocol.CwtchServerPacket{
			GroupMessage: gm,
		}
		packet, _ := proto.Marshal(csp)
		cpsc.channel.SendMessage(packet)
		cpsc.channel.CloseChannel()
	} else {
		return errors.New("channel isn't set up yet")
	}
	return nil
}

// Packet should never be
func (cpsc *CwtchPeerSendChannel) Packet(data []byte) {
	// If we receive a packet on this channel, close the connection
	cpsc.channel.CloseChannel()
}