mozim 0.3.2

DHCP Client Library
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

// SPDX-License-Identifier: Apache-2.0

use std::time::{Duration, Instant};

use super::{
    msg::{DhcpV6Message, DhcpV6MessageType},
    time::gen_retransmit_time,
    DhcpV6Config, DhcpV6Lease, DhcpV6State,
};
use crate::{DhcpError, DhcpV6Client, DhcpV6Option, ErrorKind};

// RFC 8415 section 7.6 Transmission and Retransmission Parameters
const REQ_TIMEOUT: Duration = Duration::from_secs(1);
const REQ_MAX_RT: Duration = Duration::from_secs(30);
const REQ_MAX_RC: u32 = 10;

impl DhcpV6Client {
    fn gen_request_wait_time(&self) -> Option<Duration> {
        gen_retransmit_time(
            self.trans_begin_time,
            self.retransmit_count,
            self.retransmit_timeout,
            REQ_TIMEOUT,
            REQ_MAX_RT,
            REQ_MAX_RC,
            Duration::new(0, 0),
        )
    }

    pub(crate) async fn request(&mut self) -> Result<(), DhcpError> {
        if self.retransmit_count == 0 {
            self.trans_begin_time = Instant::now();
            self.regen_xid();
        }

        loop {
            self.retransmit_timeout =
                if let Some(t) = self.gen_request_wait_time() {
                    t
                } else {
                    log::info!(
                        "Exceeded maximum wait time for Request stage, \
                         rollback to Solicit stage"
                    );
                    self.clean_up();
                    return Ok(());
                };

            match tokio::time::timeout(self.retransmit_timeout, self._request())
                .await
            {
                Ok(Ok(())) => return Ok(()),
                Ok(Err(e)) => {
                    log::info!(
                        "Retrying on error {e} after {} seconds",
                        self.retransmit_timeout.as_secs()
                    );
                    // We assume the failure is instant, so will not consider
                    // the time elapsed.
                    tokio::time::sleep(self.retransmit_timeout).await;
                }
                Err(_) => {
                    log::info!(
                        "Timeout({}s) on waiting DHCP server Reply for \
                         Request, retrying",
                        self.retransmit_timeout.as_secs(),
                    );
                    self.retransmit_count += 1;
                }
            }
        }
    }

    async fn _request(&mut self) -> Result<(), DhcpError> {
        self.state = DhcpV6State::Request;
        self.lease = None;
        let xid = self.xid;
        let pending_lease = if let Some(l) = self.pending_lease.as_ref() {
            l
        } else {
            return Err(DhcpError::new(
                ErrorKind::Bug,
                format!("No pending lease for DhcpV6State::Request {self:?}"),
            ));
        };
        let dhcp_packet = new_request_msg(
            self.xid,
            &self.config,
            &self.trans_begin_time,
            pending_lease,
        );
        let udp_socket = self.get_udp_socket_or_init().await?;

        log::debug!("Sending Request");
        log::trace!("Sending Request {dhcp_packet:?}");

        // TODO(Gris Ge): OPTION_UNICAST
        //      For Request, Renew, Information-request, Release, and Decline
        //      messages, it is allowed only if the Server Unicast option is
        //      configured.
        udp_socket.send_multicast(&dhcp_packet.emit()).await?;
        log::debug!("Waiting server reply with Reply");
        // Make sure we wait all reply from DHCP server instead of
        // failing on first DHCP invalid reply
        loop {
            match udp_socket
                .recv_dhcp_lease(DhcpV6MessageType::Reply, xid)
                .await
            {
                Ok(Some(l)) => {
                    self.done(l)?;
                    return Ok(());
                }
                Ok(None) => (),
                Err(e) => {
                    log::info!("Ignoring invalid DHCP package: {e}");
                }
            };
        }
    }
}

fn new_request_msg(
    xid: u32,
    config: &DhcpV6Config,
    trans_begin_time: &Instant,
    lease: &DhcpV6Lease,
) -> DhcpV6Message {
    let mut ret = DhcpV6Message::new(
        DhcpV6MessageType::Request,
        xid,
        &config.duid,
        trans_begin_time,
    );
    ret.options.insert(DhcpV6Option::OptionRequestOption(
        config.request_opts.clone(),
    ));
    ret.load_lease(lease);

    ret
}