crafter 0.3.1

Packet-level network interaction for Rust tools and agents.
Documentation 
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
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168

//! OSPFv2 Link State Acknowledgment packet body (RFC 2328 §A.3.6).
//!
//! The Link State Acknowledgment body follows the 24-octet common header and
//! carries the list of bare 20-octet LSA headers acknowledging the LSAs a
//! router just received from its neighbor:
//!
//! ```text
//!  0                   1                   2                   3
//!  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
//! +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//! |                                                               |
//! +-                                                             -+
//! |                             An LSA Header                      |
//! +-                                                             -+
//! |                                                               |
//! +-                                                             -+
//! |                                                               |
//! +-                                                             -+
//! |                                                               |
//! +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//! |                              ...                              ...
//! ```
//!
//! Unlike the Database Description body (RFC 2328 §A.3.3) the Link State
//! Acknowledgment has no fixed prefix: the body is just the concatenation of
//! bare 20-octet LSA headers (RFC 2328 §A.4.1), and an empty list is legal.
//! Like the other bodies, [`OspfLinkStateAck`] lives inside the
//! [`Ospfv2`](crate::protocols::ospf::Ospfv2) layer as an
//! [`OspfBody::LinkStateAck`](crate::protocols::ospf::OspfBody::LinkStateAck)
//! variant (BGP-style sub-element list); its `encode()`/`encoded_len()` are what
//! the layer's `compile()` routes to.

use crate::protocols::ospf::lsa::{encode_lsa_headers, OspfLsaHeader, OSPF_LSA_HEADER_LEN};

/// OSPFv2 Link State Acknowledgment packet body (RFC 2328 §A.3.6).
///
/// Carries the list of bare 20-octet LSA headers (RFC 2328 §A.4.1)
/// acknowledging the LSAs the originator just received. The body is just the
/// concatenation of these headers; an empty list is legal.
#[derive(Debug, Clone)]
pub struct OspfLinkStateAck {
    /// The list of bare 20-octet LSA headers (RFC 2328 §A.4.1) being
    /// acknowledged.
    lsa_headers: Vec<OspfLsaHeader>,
}

impl OspfLinkStateAck {
    /// Build a Link State Acknowledgment body with an empty LSA-header list.
    pub fn new() -> Self {
        Self {
            lsa_headers: Vec::new(),
        }
    }

    /// Construct a Link State Acknowledgment body from decoded wire headers.
    ///
    /// Consumed by the Link State Acknowledgment decoder
    /// (`decode_link_state_ack_body`) so a decoded ack re-compiles byte-for-byte.
    pub(crate) fn from_decoded_parts(lsa_headers: Vec<OspfLsaHeader>) -> Self {
        Self { lsa_headers }
    }

    /// Append a single LSA header to the acknowledgment's header list.
    pub fn lsa_header(mut self, header: OspfLsaHeader) -> Self {
        self.lsa_headers.push(header);
        self
    }

    /// Append several LSA headers to the acknowledgment's header list.
    pub fn lsa_headers<I>(mut self, headers: I) -> Self
    where
        I: IntoIterator<Item = OspfLsaHeader>,
    {
        self.lsa_headers.extend(headers);
        self
    }

    /// The LSA headers being acknowledged, in order.
    pub fn lsa_headers_value(&self) -> &[OspfLsaHeader] {
        &self.lsa_headers
    }

    /// The on-wire length of this Link State Acknowledgment body, in octets: 20
    /// octets per LSA header.
    pub(crate) fn encoded_len(&self) -> usize {
        self.lsa_headers.len() * OSPF_LSA_HEADER_LEN
    }

    /// Append the RFC 2328 §A.3.6 Link State Acknowledgment body to `out`: each
    /// bare 20-octet LSA header, in order.
    pub(crate) fn encode(&self, out: &mut Vec<u8>) {
        encode_lsa_headers(&self.lsa_headers, out);
    }
}

impl Default for OspfLinkStateAck {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use core::net::Ipv4Addr;

    /// A Link State Acknowledgment body built with two LSA headers compiles to
    /// the exact RFC 2328 §A.3.6 layout (two bare 20-octet headers, no fixed
    /// prefix), and the enclosing OSPF packet length covers the 24-octet common
    /// header plus the acknowledgment body.
    #[test]
    fn ospf_link_state_ack_body_compiles_with_two_lsa_headers() {
        use crate::packet::{Layer, Packet};
        use crate::protocols::ospf::lsa::{OspfLsaHeader, OSPF_LSA_NETWORK, OSPF_LSA_ROUTER};
        use crate::protocols::ospf::{Ospfv2, OSPF_HEADER_LEN, OSPF_TYPE_LINK_STATE_ACK};

        let ack = OspfLinkStateAck::new()
            .lsa_header(
                OspfLsaHeader::new()
                    .ls_type(OSPF_LSA_ROUTER)
                    .link_state_id(Ipv4Addr::new(192, 0, 2, 1))
                    .advertising_router(Ipv4Addr::new(192, 0, 2, 1))
                    .ls_sequence_number(0x8000_0001),
            )
            .lsa_header(
                OspfLsaHeader::new()
                    .ls_type(OSPF_LSA_NETWORK)
                    .link_state_id(Ipv4Addr::new(192, 0, 2, 2))
                    .advertising_router(Ipv4Addr::new(198, 51, 100, 7))
                    .ls_sequence_number(0x8000_0002),
            );

        // The body encodes to two bare 20-octet LSA headers, with no fixed
        // prefix.
        let mut body = Vec::new();
        ack.encode(&mut body);
        assert_eq!(ack.encoded_len(), 2 * OSPF_LSA_HEADER_LEN);
        assert_eq!(body.len(), ack.encoded_len());
        assert_eq!(body.len(), 40);

        // The two LSA headers match standalone-encoded headers, 20 octets each.
        let mut expected_headers = Vec::new();
        encode_lsa_headers(ack.lsa_headers_value(), &mut expected_headers);
        assert_eq!(body, expected_headers);
        assert_eq!(expected_headers.len(), 2 * OSPF_LSA_HEADER_LEN);

        // The ack rides inside an Ospfv2 layer; the compiled packet's Packet
        // Length field (octets 2..4) covers the common header plus the body.
        let ospf = Ospfv2::link_state_ack().with_link_state_ack(|a| {
            *a = ack.clone();
        });
        let bytes = Packet::from_layer(ospf)
            .compile()
            .expect("LinkStateAck compiles");

        let total = OSPF_HEADER_LEN + body.len();
        assert_eq!(bytes.len(), total);
        assert_eq!(&bytes[2..4], &(total as u16).to_be_bytes());
        // The header Type octet carries the Link State Acknowledgment type code.
        assert_eq!(bytes[1], OSPF_TYPE_LINK_STATE_ACK);
        // The body bytes follow the 24-octet header verbatim.
        assert_eq!(&bytes[OSPF_HEADER_LEN..], body.as_slice());

        // `Layer::encoded_len` agrees with the emitted length.
        let layer = Ospfv2::link_state_ack().with_link_state_ack(|a| *a = ack);
        assert_eq!(layer.encoded_len(), total);
    }
}