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use std::fmt;
use super::Error;
use bytes::Bytes;
/// Strip padding from the given payload.
///
/// It is assumed that the frame had the padded flag set. This means that the
/// first byte is the length of the padding with that many
/// 0 bytes expected to follow the actual payload.
///
/// # Returns
///
/// A slice of the given payload where the actual one is found and the length
/// of the padding.
///
/// If the padded payload is invalid (e.g. the length of the padding is equal
/// to the total length), returns `None`.
pub fn strip_padding(payload: &mut Bytes) -> Result<u8, Error> {
let payload_len = payload.len();
if payload_len == 0 {
// If this is the case, the frame is invalid as no padding length can be
// extracted, even though the frame should be padded.
return Err(Error::TooMuchPadding);
}
let pad_len = payload[0] as usize;
if pad_len >= payload_len {
// This is invalid: the padding length MUST be less than the
// total frame size.
return Err(Error::TooMuchPadding);
}
let _ = payload.split_to(1);
let _ = payload.split_off(payload_len - pad_len - 1);
Ok(pad_len as u8)
}
pub(super) fn debug_flags<'a, 'f: 'a>(
fmt: &'a mut fmt::Formatter<'f>,
bits: u8,
) -> DebugFlags<'a, 'f> {
let result = write!(fmt, "({:#x}", bits);
DebugFlags {
fmt,
result,
started: false,
}
}
pub(super) struct DebugFlags<'a, 'f: 'a> {
fmt: &'a mut fmt::Formatter<'f>,
result: fmt::Result,
started: bool,
}
impl<'a, 'f: 'a> DebugFlags<'a, 'f> {
pub(super) fn flag_if(&mut self, enabled: bool, name: &str) -> &mut Self {
if enabled {
self.result = self.result.and_then(|()| {
let prefix = if self.started {
" | "
} else {
self.started = true;
": "
};
write!(self.fmt, "{}{}", prefix, name)
});
}
self
}
pub(super) fn finish(&mut self) -> fmt::Result {
self.result.and_then(|()| write!(self.fmt, ")"))
}
}