/
server.go
121 lines (107 loc) · 2.62 KB
/
server.go
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package grpc
import (
"crypto/tls"
"errors"
"io"
"log/slog"
"net"
"sync"
"time"
"github.com/chenen3/yeager/flow"
"github.com/chenen3/yeager/tunnel/grpc/pb"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/keepalive"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/status"
)
const idleTimeout = 10 * time.Minute
// TunnelServer is a GRPC tunnel server, its zero value is ready to use
type TunnelServer struct {
pb.UnimplementedTunnelServer
mu sync.Mutex
gs *grpc.Server
}
// Serve will return a non-nil error unless Close is called.
func (s *TunnelServer) Serve(lis net.Listener, tlsConf *tls.Config) error {
grpcServer := grpc.NewServer(
grpc.Creds(credentials.NewTLS(tlsConf)),
grpc.KeepaliveParams(keepalive.ServerParameters{
MaxConnectionIdle: idleTimeout,
}),
grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
MinTime: keepaliveInterval,
}),
)
pb.RegisterTunnelServer(grpcServer, s)
s.mu.Lock()
s.gs = grpcServer
s.mu.Unlock()
return grpcServer.Serve(lis)
}
func (s *TunnelServer) Stream(stream pb.Tunnel_StreamServer) error {
if stream.Context().Err() != nil {
return stream.Context().Err()
}
v := metadata.ValueFromIncomingContext(stream.Context(), targetKey)
if len(v) == 0 {
return errors.New("empty target")
}
target := v[0]
conn, err := net.DialTimeout("tcp", target, 5*time.Second)
if err != nil {
return err
}
defer conn.Close()
err = flow.Relay(streamToRW(stream), conn)
if err != nil && !canIgnore(err) {
slog.Error(err.Error(), "addr", target)
}
return nil
}
func canIgnore(err error) bool {
if errors.Is(err, net.ErrClosed) {
return true
}
if s, ok := status.FromError(err); ok && s.Code() == codes.Canceled {
return true
}
return false
}
func (s *TunnelServer) Close() error {
s.mu.Lock()
defer s.mu.Unlock()
if s.gs == nil {
return nil
}
// stopping GRPC server will close all active connections and listener
s.gs.Stop()
return nil
}
type serverStreamWrapper struct {
stream pb.Tunnel_StreamServer
buf []byte
}
// convert server stream to io.ReadWriter
func streamToRW(stream pb.Tunnel_StreamServer) io.ReadWriter {
return &serverStreamWrapper{stream: stream}
}
func (ss *serverStreamWrapper) Read(b []byte) (n int, err error) {
if len(ss.buf) == 0 {
m, err := ss.stream.Recv()
if err != nil {
return 0, err
}
ss.buf = m.Data
}
n = copy(b, ss.buf)
ss.buf = ss.buf[n:]
return n, nil
}
func (ss *serverStreamWrapper) Write(b []byte) (n int, err error) {
if err = ss.stream.Send(&pb.Message{Data: b}); err != nil {
return 0, err
}
return len(b), nil
}