IT'S RIGHT

src/RawSocketWriter.zig

@@ -8,12 +8,14 @@ interface: Writer,
 socket: gcat.nic.RawSocket,
 
 fn drain(io_w: *std.Io.Writer, data: []const []const u8, splat: usize) Writer.Error!usize {
+    std.debug.print("in drain\n", .{});
     const w: *RawSocketWriter = @alignCast(@fieldParentPtr("interface", io_w));
     const rem_buf = io_w.unusedCapacitySlice();
     var rem_w = Writer.fixed(rem_buf);
     const res = rem_w.writeSplat(data, splat) catch rem_buf.len;
     io_w.advance(res);
     const buffered = io_w.buffered();
+    std.debug.print("buffer: {x}\n", .{buffered});
     w.socket.linkLayer().send(buffered) catch return error.WriteFailed;
     _ = io_w.consumeAll();
 
@@ -21,6 +23,7 @@ fn drain(io_w: *std.Io.Writer, data: []const []const u8, splat: usize) Writer.Er
 }
 
 pub fn init(interface_name: [:0]const u8, buffer: []u8) !RawSocketWriter {
+    std.debug.assert(buffer.len > 0);
     return .{
         .interface = .{
             .vtable = &.{ .drain = drain },