|
| 1 | +package vpn |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "encoding/binary" |
| 6 | + "io" |
| 7 | + "sync" |
| 8 | + |
| 9 | + "google.golang.org/protobuf/proto" |
| 10 | + |
| 11 | + "cdr.dev/slog" |
| 12 | +) |
| 13 | + |
| 14 | +// MaxLength is the largest possible CoderVPN Protocol message size. This is set |
| 15 | +// so that a misbehaving peer can't cause us to allocate a huge amount of memory. |
| 16 | +const MaxLength = 0x1000000 // 16MiB |
| 17 | + |
| 18 | +// serdes SERializes and DESerializes protobuf messages to and from the conn. |
| 19 | +type serdes[S rpcMessage, R receivableRPCMessage[RR], RR any] struct { |
| 20 | + ctx context.Context |
| 21 | + logger slog.Logger |
| 22 | + conn io.ReadWriteCloser |
| 23 | + sendCh <-chan S |
| 24 | + recvCh chan<- R |
| 25 | + closeOnce sync.Once |
| 26 | + wg sync.WaitGroup |
| 27 | +} |
| 28 | + |
| 29 | +func (s *serdes[_, R, RR]) recvLoop() { |
| 30 | + s.logger.Debug(s.ctx, "starting recvLoop") |
| 31 | + defer s.closeIdempotent() |
| 32 | + defer close(s.recvCh) |
| 33 | + for { |
| 34 | + var length uint32 |
| 35 | + if err := binary.Read(s.conn, binary.BigEndian, &length); err != nil { |
| 36 | + s.logger.Debug(s.ctx, "failed to read length", slog.Error(err)) |
| 37 | + return |
| 38 | + } |
| 39 | + if length > MaxLength { |
| 40 | + s.logger.Critical(s.ctx, "message length exceeds max", |
| 41 | + slog.F("length", length)) |
| 42 | + } |
| 43 | + s.logger.Debug(s.ctx, "about to read message", slog.F("length", length)) |
| 44 | + mb := make([]byte, length) |
| 45 | + if n, err := io.ReadFull(s.conn, mb); err != nil { |
| 46 | + s.logger.Debug(s.ctx, "failed to read message", |
| 47 | + slog.Error(err), |
| 48 | + slog.F("num_bytes_read", n)) |
| 49 | + return |
| 50 | + } |
| 51 | + msg := R(new(RR)) |
| 52 | + if err := proto.Unmarshal(mb, msg); err != nil { |
| 53 | + s.logger.Critical(s.ctx, "failed to unmarshal message", slog.Error(err)) |
| 54 | + return |
| 55 | + } |
| 56 | + select { |
| 57 | + case s.recvCh <- msg: |
| 58 | + s.logger.Debug(s.ctx, "passed received message to speaker") |
| 59 | + case <-s.ctx.Done(): |
| 60 | + s.logger.Debug(s.ctx, "recvLoop canceled", slog.Error(s.ctx.Err())) |
| 61 | + } |
| 62 | + } |
| 63 | +} |
| 64 | + |
| 65 | +func (s *serdes[S, _, _]) sendLoop() { |
| 66 | + s.logger.Debug(s.ctx, "starting sendLoop") |
| 67 | + defer s.closeIdempotent() |
| 68 | + for { |
| 69 | + select { |
| 70 | + case <-s.ctx.Done(): |
| 71 | + s.logger.Debug(s.ctx, "sendLoop canceled", slog.Error(s.ctx.Err())) |
| 72 | + return |
| 73 | + case msg, ok := <-s.sendCh: |
| 74 | + if !ok { |
| 75 | + s.logger.Debug(s.ctx, "sendCh closed") |
| 76 | + return |
| 77 | + } |
| 78 | + mb, err := proto.Marshal(msg) |
| 79 | + if err != nil { |
| 80 | + s.logger.Critical(s.ctx, "failed to marshal message", slog.Error(err)) |
| 81 | + return |
| 82 | + } |
| 83 | + if err := binary.Write(s.conn, binary.BigEndian, uint32(len(mb))); err != nil { |
| 84 | + s.logger.Debug(s.ctx, "failed to write length", slog.Error(err)) |
| 85 | + return |
| 86 | + } |
| 87 | + if _, err := s.conn.Write(mb); err != nil { |
| 88 | + s.logger.Debug(s.ctx, "failed to write message", slog.Error(err)) |
| 89 | + return |
| 90 | + } |
| 91 | + } |
| 92 | + } |
| 93 | +} |
| 94 | + |
| 95 | +func (s *serdes[_, _, _]) closeIdempotent() { |
| 96 | + s.closeOnce.Do(func() { |
| 97 | + if err := s.conn.Close(); err != nil { |
| 98 | + s.logger.Error(s.ctx, "failed to close connection", slog.Error(err)) |
| 99 | + } else { |
| 100 | + s.logger.Info(s.ctx, "closed connection") |
| 101 | + } |
| 102 | + }) |
| 103 | +} |
| 104 | + |
| 105 | +func (s *serdes[_, _, _]) Close() error { |
| 106 | + s.closeIdempotent() |
| 107 | + s.wg.Wait() |
| 108 | + return nil |
| 109 | +} |
| 110 | + |
| 111 | +func (s *serdes[_, _, _]) start() { |
| 112 | + s.wg.Add(2) |
| 113 | + go func() { |
| 114 | + defer s.wg.Done() |
| 115 | + s.recvLoop() |
| 116 | + }() |
| 117 | + go func() { |
| 118 | + defer s.wg.Done() |
| 119 | + s.sendLoop() |
| 120 | + }() |
| 121 | +} |
| 122 | + |
| 123 | +func newSerdes[S rpcMessage, R receivableRPCMessage[RR], RR any]( |
| 124 | + ctx context.Context, logger slog.Logger, conn io.ReadWriteCloser, |
| 125 | + sendCh <-chan S, recvCh chan<- R, |
| 126 | +) *serdes[S, R, RR] { |
| 127 | + return &serdes[S, R, RR]{ |
| 128 | + ctx: ctx, |
| 129 | + logger: logger.Named("serdes"), |
| 130 | + conn: conn, |
| 131 | + sendCh: sendCh, |
| 132 | + recvCh: recvCh, |
| 133 | + } |
| 134 | +} |
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