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Blob: firmware/vendor/sctp-proto/src/chunk/chunk_selective_ack.rs

rust159 lines
1use super::{chunk_header::*, chunk_type::*, *};
2 
3///chunkSelectiveAck represents an SCTP Chunk of type SACK
4///
5///This chunk is sent to the peer endpoint to acknowledge received DATA
6///chunks and to inform the peer endpoint of gaps in the received
7///subsequences of DATA chunks as represented by their TSNs.
8///0                   1                   2                   3
9///0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
10///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11///|   Type = 3    |Chunk  Flags   |      Chunk Length             |
12///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
13///|                      Cumulative TSN Ack                       |
14///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
15///|          Advertised Receiver Window Credit (a_rwnd)           |
16///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17///| Number of Gap Ack Blocks = N  |  Number of Duplicate TSNs = X |
18///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
19///|  Gap Ack Block #1 Start       |   Gap Ack Block #1 End        |
20///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
21///|                                                               |
22///|                              ...                              |
23///|                                                               |
24///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
25///|   Gap Ack Block #N Start      |  Gap Ack Block #N End         |
26///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
27///|                       Duplicate TSN 1                         |
28///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
29///|                                                               |
30///|                              ...                              |
31///|                                                               |
32///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
33///|                       Duplicate TSN X                         |
34///+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
35#[derive(Debug, Default, Copy, Clone)]
36pub(crate) struct GapAckBlock {
37    pub(crate) start: u16,
38    pub(crate) end: u16,
39}
40 
41/// makes gapAckBlock printable
42impl fmt::Display for GapAckBlock {
43    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
44        write!(f, "{} - {}", self.start, self.end)
45    }
46}
47 
48#[derive(Default, Debug)]
49pub(crate) struct ChunkSelectiveAck {
50    pub(crate) cumulative_tsn_ack: u32,
51    pub(crate) advertised_receiver_window_credit: u32,
52    pub(crate) gap_ack_blocks: Vec<GapAckBlock>,
53    pub(crate) duplicate_tsn: Vec<u32>,
54}
55 
56/// makes chunkSelectiveAck printable
57impl fmt::Display for ChunkSelectiveAck {
58    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
59        let mut res = format!(
60            "SACK cumTsnAck={} arwnd={} dupTsn={:?}",
61            self.cumulative_tsn_ack, self.advertised_receiver_window_credit, self.duplicate_tsn
62        );
63 
64        for gap in &self.gap_ack_blocks {
65            res += format!("\n gap ack: {}", gap).as_str();
66        }
67 
68        write!(f, "{}", res)
69    }
70}
71 
72pub(crate) const SELECTIVE_ACK_HEADER_SIZE: usize = 12;
73 
74impl Chunk for ChunkSelectiveAck {
75    fn header(&self) -> ChunkHeader {
76        ChunkHeader {
77            typ: CT_SACK,
78            flags: 0,
79            value_length: self.value_length() as u16,
80        }
81    }
82 
83    fn unmarshal(raw: &Bytes) -> Result<Self> {
84        let header = ChunkHeader::unmarshal(raw)?;
85 
86        if header.typ != CT_SACK {
87            return Err(Error::ErrChunkTypeNotSack);
88        }
89 
90        if header.value_length() < SELECTIVE_ACK_HEADER_SIZE {
91            return Err(Error::ErrSackSizeNotLargeEnoughInfo);
92        }
93 
94        let reader = &mut raw.slice(CHUNK_HEADER_SIZE..CHUNK_HEADER_SIZE + header.value_length());
95 
96        let cumulative_tsn_ack = reader.get_u32();
97        let advertised_receiver_window_credit = reader.get_u32();
98        let gap_ack_blocks_len = reader.get_u16() as usize;
99        let duplicate_tsn_len = reader.get_u16() as usize;
100 
101        // The reader is bounded by header.value_length(), so we
102        // must check against that, not raw.len() which may include
103        // subsequent chunks.
104        if header.value_length()
105            < SELECTIVE_ACK_HEADER_SIZE + (4 * gap_ack_blocks_len + 4 * duplicate_tsn_len)
106        {
107            return Err(Error::ErrSackSizeNotLargeEnoughInfo);
108        }
109 
110        let mut gap_ack_blocks = vec![];
111        let mut duplicate_tsn = vec![];
112        for _ in 0..gap_ack_blocks_len {
113            let start = reader.get_u16();
114            let end = reader.get_u16();
115            gap_ack_blocks.push(GapAckBlock { start, end });
116        }
117        for _ in 0..duplicate_tsn_len {
118            duplicate_tsn.push(reader.get_u32());
119        }
120 
121        Ok(ChunkSelectiveAck {
122            cumulative_tsn_ack,
123            advertised_receiver_window_credit,
124            gap_ack_blocks,
125            duplicate_tsn,
126        })
127    }
128 
129    fn marshal_to(&self, writer: &mut BytesMut) -> Result<usize> {
130        self.header().marshal_to(writer)?;
131 
132        writer.put_u32(self.cumulative_tsn_ack);
133        writer.put_u32(self.advertised_receiver_window_credit);
134        writer.put_u16(self.gap_ack_blocks.len() as u16);
135        writer.put_u16(self.duplicate_tsn.len() as u16);
136        for g in &self.gap_ack_blocks {
137            writer.put_u16(g.start);
138            writer.put_u16(g.end);
139        }
140        for t in &self.duplicate_tsn {
141            writer.put_u32(*t);
142        }
143 
144        Ok(writer.len())
145    }
146 
147    fn check(&self) -> Result<()> {
148        Ok(())
149    }
150 
151    fn value_length(&self) -> usize {
152        SELECTIVE_ACK_HEADER_SIZE + self.gap_ack_blocks.len() * 4 + self.duplicate_tsn.len() * 4
153    }
154 
155    fn as_any(&self) -> &(dyn Any + Send + Sync) {
156        self
157    }
158}