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grpc.go
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grpc.go
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package client
import (
"context"
"crypto/tls"
"fmt"
"github.com/cenkalti/backoff/v4"
log "github.com/sirupsen/logrus"
"github.com/wiretrustee/wiretrustee/encryption"
"github.com/wiretrustee/wiretrustee/signal/proto"
"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/connectivity"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/credentials/insecure"
"google.golang.org/grpc/keepalive"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/status"
"io"
"sync"
"time"
)
// GrpcClient Wraps the Signal Exchange Service gRpc client
type GrpcClient struct {
key wgtypes.Key
realClient proto.SignalExchangeClient
signalConn *grpc.ClientConn
ctx context.Context
stream proto.SignalExchange_ConnectStreamClient
// connectedCh used to notify goroutines waiting for the connection to the Signal stream
connectedCh chan struct{}
mux sync.Mutex
// StreamConnected indicates whether this client is StreamConnected to the Signal stream
status Status
}
func (c *GrpcClient) StreamConnected() bool {
return c.status == StreamConnected
}
func (c *GrpcClient) GetStatus() Status {
return c.status
}
// Close Closes underlying connections to the Signal Exchange
func (c *GrpcClient) Close() error {
return c.signalConn.Close()
}
// NewClient creates a new Signal client
func NewClient(ctx context.Context, addr string, key wgtypes.Key, tlsEnabled bool) (*GrpcClient, error) {
transportOption := grpc.WithTransportCredentials(insecure.NewCredentials())
if tlsEnabled {
transportOption = grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{}))
}
sigCtx, cancel := context.WithTimeout(ctx, time.Second*3)
defer cancel()
conn, err := grpc.DialContext(
sigCtx,
addr,
transportOption,
grpc.WithBlock(),
grpc.WithKeepaliveParams(keepalive.ClientParameters{
Time: 15 * time.Second,
Timeout: 10 * time.Second,
}))
if err != nil {
log.Errorf("failed to connect to the signalling server %v", err)
return nil, err
}
return &GrpcClient{
realClient: proto.NewSignalExchangeClient(conn),
ctx: ctx,
signalConn: conn,
key: key,
mux: sync.Mutex{},
status: StreamDisconnected,
}, nil
}
//defaultBackoff is a basic backoff mechanism for general issues
func defaultBackoff(ctx context.Context) backoff.BackOff {
return backoff.WithContext(&backoff.ExponentialBackOff{
InitialInterval: 800 * time.Millisecond,
RandomizationFactor: backoff.DefaultRandomizationFactor,
Multiplier: backoff.DefaultMultiplier,
MaxInterval: 10 * time.Second,
MaxElapsedTime: 12 * time.Hour, //stop after 12 hours of trying, the error will be propagated to the general retry of the client
Stop: backoff.Stop,
Clock: backoff.SystemClock,
}, ctx)
}
// Receive Connects to the Signal Exchange message stream and starts receiving messages.
// The messages will be handled by msgHandler function provided.
// This function is blocking and reconnects to the Signal Exchange if errors occur (e.g. Exchange restart)
// The connection retry logic will try to reconnect for 30 min and if wasn't successful will propagate the error to the function caller.
func (c *GrpcClient) Receive(msgHandler func(msg *proto.Message) error) error {
var backOff = defaultBackoff(c.ctx)
operation := func() error {
c.notifyStreamDisconnected()
log.Debugf("signal connection state %v", c.signalConn.GetState())
if !c.Ready() {
return fmt.Errorf("no connection to signal")
}
// connect to Signal stream identifying ourselves with a public Wireguard key
// todo once the key rotation logic has been implemented, consider changing to some other identifier (received from management)
stream, err := c.connect(c.key.PublicKey().String())
if err != nil {
log.Warnf("disconnected from the Signal Exchange due to an error: %v", err)
return err
}
c.notifyStreamConnected()
log.Infof("connected to the Signal Service stream")
// start receiving messages from the Signal stream (from other peers through signal)
err = c.receive(stream, msgHandler)
if err != nil {
log.Warnf("disconnected from the Signal Exchange due to an error: %v", err)
backOff.Reset()
return err
}
return nil
}
err := backoff.Retry(operation, backOff)
if err != nil {
log.Errorf("exiting Signal Service connection retry loop due to unrecoverable error: %s", err)
return err
}
return nil
}
func (c *GrpcClient) notifyStreamDisconnected() {
c.mux.Lock()
defer c.mux.Unlock()
c.status = StreamDisconnected
}
func (c *GrpcClient) notifyStreamConnected() {
c.mux.Lock()
defer c.mux.Unlock()
c.status = StreamConnected
if c.connectedCh != nil {
// there are goroutines waiting on this channel -> release them
close(c.connectedCh)
c.connectedCh = nil
}
}
func (c *GrpcClient) getStreamStatusChan() <-chan struct{} {
c.mux.Lock()
defer c.mux.Unlock()
if c.connectedCh == nil {
c.connectedCh = make(chan struct{})
}
return c.connectedCh
}
func (c *GrpcClient) connect(key string) (proto.SignalExchange_ConnectStreamClient, error) {
c.stream = nil
// add key fingerprint to the request header to be identified on the server side
md := metadata.New(map[string]string{proto.HeaderId: key})
ctx := metadata.NewOutgoingContext(c.ctx, md)
stream, err := c.realClient.ConnectStream(ctx, grpc.WaitForReady(true))
c.stream = stream
if err != nil {
return nil, err
}
// blocks
header, err := c.stream.Header()
if err != nil {
return nil, err
}
registered := header.Get(proto.HeaderRegistered)
if len(registered) == 0 {
return nil, fmt.Errorf("didn't receive a registration header from the Signal server whille connecting to the streams")
}
return stream, nil
}
// Ready indicates whether the client is okay and Ready to be used
// for now it just checks whether gRPC connection to the service is in state Ready
func (c *GrpcClient) Ready() bool {
return c.signalConn.GetState() == connectivity.Ready || c.signalConn.GetState() == connectivity.Idle
}
// WaitStreamConnected waits until the client is connected to the Signal stream
func (c *GrpcClient) WaitStreamConnected() {
if c.status == StreamConnected {
return
}
ch := c.getStreamStatusChan()
select {
case <-c.ctx.Done():
case <-ch:
}
}
// SendToStream sends a message to the remote Peer through the Signal Exchange using established stream connection to the Signal Server
// The GrpcClient.Receive method must be called before sending messages to establish initial connection to the Signal Exchange
// GrpcClient.connWg can be used to wait
func (c *GrpcClient) SendToStream(msg *proto.EncryptedMessage) error {
if !c.Ready() {
return fmt.Errorf("no connection to signal")
}
if c.stream == nil {
return fmt.Errorf("connection to the Signal Exchnage has not been established yet. Please call GrpcClient.Receive before sending messages")
}
err := c.stream.Send(msg)
if err != nil {
log.Errorf("error while sending message to peer [%s] [error: %v]", msg.RemoteKey, err)
return err
}
return nil
}
// decryptMessage decrypts the body of the msg using Wireguard private key and Remote peer's public key
func (c *GrpcClient) decryptMessage(msg *proto.EncryptedMessage) (*proto.Message, error) {
remoteKey, err := wgtypes.ParseKey(msg.GetKey())
if err != nil {
return nil, err
}
body := &proto.Body{}
err = encryption.DecryptMessage(remoteKey, c.key, msg.GetBody(), body)
if err != nil {
return nil, err
}
return &proto.Message{
Key: msg.Key,
RemoteKey: msg.RemoteKey,
Body: body,
}, nil
}
// encryptMessage encrypts the body of the msg using Wireguard private key and Remote peer's public key
func (c *GrpcClient) encryptMessage(msg *proto.Message) (*proto.EncryptedMessage, error) {
remoteKey, err := wgtypes.ParseKey(msg.RemoteKey)
if err != nil {
return nil, err
}
encryptedBody, err := encryption.EncryptMessage(remoteKey, c.key, msg.Body)
if err != nil {
return nil, err
}
return &proto.EncryptedMessage{
Key: msg.GetKey(),
RemoteKey: msg.GetRemoteKey(),
Body: encryptedBody,
}, nil
}
// Send sends a message to the remote Peer through the Signal Exchange.
func (c *GrpcClient) Send(msg *proto.Message) error {
if !c.Ready() {
return fmt.Errorf("no connection to signal")
}
encryptedMessage, err := c.encryptMessage(msg)
if err != nil {
return err
}
ctx, cancel := context.WithTimeout(context.Background(), time.Second*2)
defer cancel()
_, err = c.realClient.Send(ctx, encryptedMessage)
if err != nil {
return err
}
return nil
}
// receive receives messages from other peers coming through the Signal Exchange
func (c *GrpcClient) receive(stream proto.SignalExchange_ConnectStreamClient,
msgHandler func(msg *proto.Message) error) error {
for {
msg, err := stream.Recv()
if s, ok := status.FromError(err); ok && s.Code() == codes.Canceled {
log.Warnf("stream canceled (usually indicates shutdown)")
return err
} else if s.Code() == codes.Unavailable {
log.Warnf("Signal Service is unavailable")
return err
} else if err == io.EOF {
log.Warnf("Signal Service stream closed by server")
return err
} else if err != nil {
return err
}
log.Debugf("received a new message from Peer [fingerprint: %s]", msg.Key)
decryptedMessage, err := c.decryptMessage(msg)
if err != nil {
log.Errorf("failed decrypting message of Peer [key: %s] error: [%s]", msg.Key, err.Error())
}
err = msgHandler(decryptedMessage)
if err != nil {
log.Errorf("error while handling message of Peer [key: %s] error: [%s]", msg.Key, err.Error())
//todo send something??
}
}
}