initial commit

desktop-daemon/src/net/framing.odin

@@ -0,0 +1,98 @@
+package clipsync_net
+
+import cnet "core:net"
+
+// TCP framing for protocol v1:
+// [4-byte big-endian length][UTF-8 JSON payload]
+
+MAX_FRAME_BYTES :: 1024 * 1024 // 1 MiB
+
+Framing_Error :: enum {
+	None,
+	Frame_Too_Large,
+	Connection_Closed,
+	Socket_Recv_Failed,
+	Socket_Send_Failed,
+}
+
+u32_to_be_bytes :: proc(v: u32) -> [4]byte {
+	return [4]byte{
+		byte((v >> 24) & 0xff),
+		byte((v >> 16) & 0xff),
+		byte((v >> 8) & 0xff),
+		byte(v & 0xff),
+	}
+}
+
+be_bytes_to_u32 :: proc(prefix: [4]byte) -> u32 {
+	return (u32(prefix[0]) << 24) |
+		(u32(prefix[1]) << 16) |
+		(u32(prefix[2]) << 8) |
+		u32(prefix[3])
+}
+
+recv_exact :: proc(socket: cnet.TCP_Socket, out: []byte) -> Framing_Error {
+	offset := 0
+	for offset < len(out) {
+		read, err := cnet.recv_tcp(socket, out[offset:])
+		if err != nil {
+			return .Socket_Recv_Failed
+		}
+		if read == 0 {
+			return .Connection_Closed
+		}
+		offset += read
+	}
+	return .None
+}
+
+send_all :: proc(socket: cnet.TCP_Socket, data: []byte) -> Framing_Error {
+	offset := 0
+	for offset < len(data) {
+		written, err := cnet.send_tcp(socket, data[offset:])
+		if err != nil {
+			return .Socket_Send_Failed
+		}
+		if written == 0 {
+			return .Connection_Closed
+		}
+		offset += written
+	}
+	return .None
+}
+
+send_frame :: proc(socket: cnet.TCP_Socket, payload: []byte) -> Framing_Error {
+	if len(payload) > MAX_FRAME_BYTES {
+		return .Frame_Too_Large
+	}
+
+	prefix := u32_to_be_bytes(u32(len(payload)))
+	if err := send_all(socket, prefix[:]); err != .None {
+		return err
+	}
+	return send_all(socket, payload)
+}
+
+recv_frame :: proc(socket: cnet.TCP_Socket, allocator := context.allocator) -> ([]byte, Framing_Error) {
+	len_prefix: [4]byte
+	if err := recv_exact(socket, len_prefix[:]); err != .None {
+		return nil, err
+	}
+
+	size := int(be_bytes_to_u32(len_prefix))
+	if size > MAX_FRAME_BYTES {
+		return nil, .Frame_Too_Large
+	}
+
+	buf := make([]byte, size, allocator)
+	if size == 0 {
+		return buf, .None
+	}
+
+	if err := recv_exact(socket, buf); err != .None {
+		delete(buf)
+		return nil, err
+	}
+
+	return buf, .None
+}