1
use super::list::private::WordSized;
2
use super::{FeedbackMessageType, PayloadType, ReportList, RtcpHeader, RtcpPacket, RtcpType, Ssrc};
3
 
4
/// Full Intra Request (FIR).
5
#[derive(Debug, Clone, PartialEq, Eq)]
6
pub struct Fir {
7
    /// Sender of this feedback. Mostly irrelevant, but part of RTCP packets.
8
    pub sender_ssrc: Ssrc,
9
    /// The SSRC needing a full codec restart.
10
    pub reports: ReportList<FirEntry>,
11
}
12
 
13
/// Entry reported needing a codec restart.
14
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
15
pub struct FirEntry {
16
    /// The SSRC needing a full codec restart.
17
    pub ssrc: Ssrc,
18
    /// Counter keeping track of which restart request this is.
19
    pub seq_no: u8,
20
}
21
 
22
impl RtcpPacket for Fir {
23
    fn header(&self) -> RtcpHeader {
24
        RtcpHeader {
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            rtcp_type: RtcpType::PayloadSpecificFeedback,
26
            feedback_message_type: FeedbackMessageType::PayloadFeedback(
27
                PayloadType::FullIntraRequest,
28
            ),
29
            words_less_one: (self.length_words() - 1) as u16,
30
        }
31
    }
32
 
33
    fn length_words(&self) -> usize {
34
        // header
35
        // sender SSRC
36
        // media SSRC (set to 0)
37
        // reports * FirEntry: SSRC + seqNo
38
        1 + 1 + 1 + self.reports.len() * 2
39
    }
40
 
41
    fn write_to(&self, buf: &mut [u8]) -> usize {
42
        self.header().write_to(&mut buf[..4]);
43
 
44
        buf[4..8].copy_from_slice(&self.sender_ssrc.to_be_bytes());
45
 
46
        let media_ssrc = self.reports.iter().next().map(|s| *s.ssrc).unwrap_or(0);
47
        buf[8..12].copy_from_slice(&media_ssrc.to_be_bytes());
48
 
49
        let mut buf = &mut buf[12..];
50
        for r in &self.reports {
51
            buf[0..4].copy_from_slice(&r.ssrc.to_be_bytes());
52
            buf[4..8].copy_from_slice(&[r.seq_no, 0, 0, 0]);
53
            buf = &mut buf[8..];
54
        }
55
 
56
        4 + 4 + 4 + self.reports.len() * 8
57
    }
58
}
59
 
60
impl WordSized for FirEntry {
61
    fn word_size(&self) -> usize {
62
        2
63
    }
64
}
65
 
66
impl<'a> TryFrom<&'a [u8]> for Fir {
67
    type Error = &'static str;
68
 
69
    fn try_from(buf: &'a [u8]) -> Result<Self, Self::Error> {
70
        if buf.len() < 16 {
71
            return Err("Fir less than 16 bytes");
72
        }
73
 
74
        let sender_ssrc = u32::from_be_bytes([buf[0], buf[1], buf[2], buf[3]]).into();
75
 
76
        let mut reports = ReportList::new();
77
 
78
        let mut buf = &buf[8..];
79
        let count = buf.len() / 8;
80
        let max = count.min(31);
81
 
82
        for _ in 0..max {
83
            let ssrc = u32::from_be_bytes([buf[0], buf[1], buf[2], buf[3]]).into();
84
            let seq_no = buf[4];
85
            reports.push(FirEntry { ssrc, seq_no });
86
            buf = &buf[8..];
87
        }
88
 
89
        Ok(Fir {
90
            sender_ssrc,
91
            reports,
92
        })
93
    }
94
}