flowscope 0.12.0

Passive flow & session tracking for packet capture (runtime-free, cross-platform)
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

//! [`LayerKind`] — discriminant used by [`Layers::find`](super::Layers::find)
//! / [`Layers::find_all`](super::Layers::find_all) and on every
//! per-layer slice.

use std::fmt;

/// Identifies one parsed layer in a packet.
///
/// Used as the discriminant for `Layer<'_>` and as the lookup key
/// in [`Layers::find`](super::Layers::find) /
/// [`Layers::find_all`](super::Layers::find_all). Pattern-match on
/// it for "any IP layer", "any L4", etc.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[non_exhaustive]
pub enum LayerKind {
    /// Ethernet II (link layer).
    Ethernet,
    /// 802.1Q VLAN tag.
    Vlan,
    /// MPLS label-stack entry.
    Mpls,
    /// IPv4.
    Ipv4,
    /// IPv6.
    Ipv6,
    /// ARP (Address Resolution Protocol).
    Arp,
    /// TCP.
    Tcp,
    /// UDP.
    Udp,
    /// ICMPv4.
    Icmpv4,
    /// ICMPv6.
    Icmpv6,
    /// GRE tunnel header (RFC 2784 / 2890).
    Gre,
    /// VXLAN tunnel header (RFC 7348).
    Vxlan,
    /// GTP-U tunnel header (3GPP TS 29.281).
    GtpU,
    /// Unparsed bytes after the last recognised header.
    Payload,
}

impl LayerKind {
    /// OSI L-number group: 2 (link), 3 (net), 4 (transport),
    /// 4.5 returned as 4 (ICMP/tunnels conventionally L4), or
    /// 7 (payload).
    pub fn layer_number(&self) -> u8 {
        match self {
            LayerKind::Ethernet | LayerKind::Vlan | LayerKind::Mpls => 2,
            LayerKind::Ipv4 | LayerKind::Ipv6 | LayerKind::Arp => 3,
            LayerKind::Tcp
            | LayerKind::Udp
            | LayerKind::Icmpv4
            | LayerKind::Icmpv6
            | LayerKind::Gre
            | LayerKind::Vxlan
            | LayerKind::GtpU => 4,
            LayerKind::Payload => 7,
        }
    }

    /// `true` if this kind is a link-layer header (Ethernet / VLAN
    /// / MPLS). New in 0.10.0.
    pub const fn is_l2(self) -> bool {
        matches!(
            self,
            LayerKind::Ethernet | LayerKind::Vlan | LayerKind::Mpls
        )
    }

    /// `true` if this kind is a network-layer header
    /// (IPv4 / IPv6 / ARP). New in 0.10.0.
    pub const fn is_l3(self) -> bool {
        matches!(self, LayerKind::Ipv4 | LayerKind::Ipv6 | LayerKind::Arp)
    }

    /// `true` if this kind is a transport-layer header
    /// (TCP / UDP / ICMPv4 / ICMPv6). Tunnel headers are reported
    /// by [`Self::is_tunnel`], not here, even though they share
    /// the L4 group via [`Self::layer_number`]. New in 0.10.0.
    pub const fn is_l4(self) -> bool {
        matches!(
            self,
            LayerKind::Tcp | LayerKind::Udp | LayerKind::Icmpv4 | LayerKind::Icmpv6
        )
    }

    /// `true` if this kind wraps another layered stack
    /// (GRE / VXLAN / GTP-U). New in 0.10.0.
    pub const fn is_tunnel(self) -> bool {
        matches!(self, LayerKind::Gre | LayerKind::Vxlan | LayerKind::GtpU)
    }
}

impl fmt::Display for LayerKind {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let s = match self {
            LayerKind::Ethernet => "ethernet",
            LayerKind::Vlan => "vlan",
            LayerKind::Mpls => "mpls",
            LayerKind::Ipv4 => "ipv4",
            LayerKind::Ipv6 => "ipv6",
            LayerKind::Arp => "arp",
            LayerKind::Tcp => "tcp",
            LayerKind::Udp => "udp",
            LayerKind::Icmpv4 => "icmpv4",
            LayerKind::Icmpv6 => "icmpv6",
            LayerKind::Gre => "gre",
            LayerKind::Vxlan => "vxlan",
            LayerKind::GtpU => "gtpu",
            LayerKind::Payload => "payload",
        };
        f.write_str(s)
    }
}

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

    #[test]
    fn layer_numbers() {
        assert_eq!(LayerKind::Ethernet.layer_number(), 2);
        assert_eq!(LayerKind::Vlan.layer_number(), 2);
        assert_eq!(LayerKind::Mpls.layer_number(), 2);
        assert_eq!(LayerKind::Ipv4.layer_number(), 3);
        assert_eq!(LayerKind::Ipv6.layer_number(), 3);
        assert_eq!(LayerKind::Arp.layer_number(), 3);
        assert_eq!(LayerKind::Tcp.layer_number(), 4);
        assert_eq!(LayerKind::Udp.layer_number(), 4);
        assert_eq!(LayerKind::Icmpv4.layer_number(), 4);
        assert_eq!(LayerKind::Icmpv6.layer_number(), 4);
        assert_eq!(LayerKind::Gre.layer_number(), 4);
        assert_eq!(LayerKind::Vxlan.layer_number(), 4);
        assert_eq!(LayerKind::GtpU.layer_number(), 4);
        assert_eq!(LayerKind::Payload.layer_number(), 7);
    }

    #[test]
    fn display_lowercase() {
        assert_eq!(LayerKind::Tcp.to_string(), "tcp");
        assert_eq!(LayerKind::Ethernet.to_string(), "ethernet");
    }
}