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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189

use core::fmt;

use crate::phy::{self, Device, DeviceCapabilities, Medium};
use crate::time::Instant;
use crate::wire::pretty_print::{PrettyIndent, PrettyPrint};

/// A tracer device.
///
/// A tracer is a device that pretty prints all packets traversing it
/// using the provided writer function, and then passes them to another
/// device.
pub struct Tracer<D: Device> {
    inner: D,
    writer: fn(Instant, Packet),
}

impl<D: Device> Tracer<D> {
    /// Create a tracer device.
    pub fn new(inner: D, writer: fn(timestamp: Instant, packet: Packet)) -> Tracer<D> {
        Tracer { inner, writer }
    }

    /// Get a reference to the underlying device.
    ///
    /// Even if the device offers reading through a standard reference, it is inadvisable to
    /// directly read from the device as doing so will circumvent the tracing.
    pub fn get_ref(&self) -> &D {
        &self.inner
    }

    /// Get a mutable reference to the underlying device.
    ///
    /// It is inadvisable to directly read from the device as doing so will circumvent the tracing.
    pub fn get_mut(&mut self) -> &mut D {
        &mut self.inner
    }

    /// Return the underlying device, consuming the tracer.
    pub fn into_inner(self) -> D {
        self.inner
    }
}

impl<D: Device> Device for Tracer<D> {
    type RxToken<'a> = RxToken<D::RxToken<'a>>
    where
        Self: 'a;
    type TxToken<'a> = TxToken<D::TxToken<'a>>
    where
        Self: 'a;

    fn capabilities(&self) -> DeviceCapabilities {
        self.inner.capabilities()
    }

    fn receive(&mut self, timestamp: Instant) -> Option<(Self::RxToken<'_>, Self::TxToken<'_>)> {
        let medium = self.inner.capabilities().medium;
        self.inner.receive(timestamp).map(|(rx_token, tx_token)| {
            let rx = RxToken {
                token: rx_token,
                writer: self.writer,
                medium,
                timestamp,
            };
            let tx = TxToken {
                token: tx_token,
                writer: self.writer,
                medium,
                timestamp,
            };
            (rx, tx)
        })
    }

    fn transmit(&mut self, timestamp: Instant) -> Option<Self::TxToken<'_>> {
        let medium = self.inner.capabilities().medium;
        self.inner.transmit(timestamp).map(|tx_token| TxToken {
            token: tx_token,
            medium,
            writer: self.writer,
            timestamp,
        })
    }
}

#[doc(hidden)]
pub struct RxToken<Rx: phy::RxToken> {
    token: Rx,
    writer: fn(Instant, Packet),
    medium: Medium,
    timestamp: Instant,
}

impl<Rx: phy::RxToken> phy::RxToken for RxToken<Rx> {
    fn consume<R, F>(self, f: F) -> R
    where
        F: FnOnce(&mut [u8]) -> R,
    {
        self.token.consume(|buffer| {
            (self.writer)(
                self.timestamp,
                Packet {
                    buffer,
                    medium: self.medium,
                    prefix: "<- ",
                },
            );
            f(buffer)
        })
    }

    fn meta(&self) -> phy::PacketMeta {
        self.token.meta()
    }
}

#[doc(hidden)]
pub struct TxToken<Tx: phy::TxToken> {
    token: Tx,
    writer: fn(Instant, Packet),
    medium: Medium,
    timestamp: Instant,
}

impl<Tx: phy::TxToken> phy::TxToken for TxToken<Tx> {
    fn consume<R, F>(self, len: usize, f: F) -> R
    where
        F: FnOnce(&mut [u8]) -> R,
    {
        self.token.consume(len, |buffer| {
            let result = f(buffer);
            (self.writer)(
                self.timestamp,
                Packet {
                    buffer,
                    medium: self.medium,
                    prefix: "-> ",
                },
            );
            result
        })
    }

    fn set_meta(&mut self, meta: phy::PacketMeta) {
        self.token.set_meta(meta)
    }
}

pub struct Packet<'a> {
    buffer: &'a [u8],
    medium: Medium,
    prefix: &'static str,
}

impl<'a> fmt::Display for Packet<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut indent = PrettyIndent::new(self.prefix);
        match self.medium {
            #[cfg(feature = "medium-ethernet")]
            Medium::Ethernet => crate::wire::EthernetFrame::<&'static [u8]>::pretty_print(
                &self.buffer,
                f,
                &mut indent,
            ),
            #[cfg(feature = "medium-ip")]
            Medium::Ip => match crate::wire::IpVersion::of_packet(self.buffer) {
                #[cfg(feature = "proto-ipv4")]
                Ok(crate::wire::IpVersion::Ipv4) => {
                    crate::wire::Ipv4Packet::<&'static [u8]>::pretty_print(
                        &self.buffer,
                        f,
                        &mut indent,
                    )
                }
                #[cfg(feature = "proto-ipv6")]
                Ok(crate::wire::IpVersion::Ipv6) => {
                    crate::wire::Ipv6Packet::<&'static [u8]>::pretty_print(
                        &self.buffer,
                        f,
                        &mut indent,
                    )
                }
                _ => f.write_str("unrecognized IP version"),
            },
            #[cfg(feature = "medium-ieee802154")]
            Medium::Ieee802154 => Ok(()), // XXX
        }
    }
}