summaryrefslogtreecommitdiffstats
path: root/third_party/rust/h2/src/frame/util.rs
blob: 6bee7bd9bbfa1c38c79042ab659025d7d5923689 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
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, ")"))
    }
}