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dhcpv4: parse and emit DHCP Option 42 (NTP servers) #1205

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dhcpv4: parse and emit DHCP Option 42 (NTP servers) #1205

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43 changes: 36 additions & 7 deletions src/socket/dhcpv4.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,9 @@ use crate::iface::Context;
use crate::time::{Duration, Instant};
use crate::wire::dhcpv4::field as dhcpv4_field;
use crate::wire::{
DHCP_CLIENT_PORT, DHCP_MAX_DNS_SERVER_COUNT, DHCP_SERVER_PORT, DhcpMessageType, DhcpPacket,
DhcpRepr, IpAddress, IpProtocol, Ipv4Address, Ipv4AddressExt, Ipv4Cidr, Ipv4Repr,
UDP_HEADER_LEN, UdpRepr,
DHCP_CLIENT_PORT, DHCP_MAX_DNS_SERVER_COUNT, DHCP_MAX_NTP_SERVER_COUNT, DHCP_SERVER_PORT,
DhcpMessageType, DhcpPacket, DhcpRepr, IpAddress, IpProtocol, Ipv4Address, Ipv4AddressExt,
Ipv4Cidr, Ipv4Repr, UDP_HEADER_LEN, UdpRepr,
};
use crate::wire::{DhcpOption, HardwareAddress};
use heapless::Vec;
Expand All @@ -23,6 +23,7 @@ const DEFAULT_PARAMETER_REQUEST_LIST: &[u8] = &[
dhcpv4_field::OPT_SUBNET_MASK,
dhcpv4_field::OPT_ROUTER,
dhcpv4_field::OPT_DOMAIN_NAME_SERVER,
dhcpv4_field::OPT_NTP_SERVERS,
];

/// IPv4 configuration data provided by the DHCP server.
Expand All @@ -39,6 +40,8 @@ pub struct Config<'a> {
pub router: Option<Ipv4Address>,
/// DNS servers
pub dns_servers: Vec<Ipv4Address, DHCP_MAX_DNS_SERVER_COUNT>,
/// NTP servers (RFC 2132 §8.3)
pub ntp_servers: Vec<Ipv4Address, DHCP_MAX_NTP_SERVER_COUNT>,
/// Received DHCP packet
pub packet: Option<DhcpPacket<&'a [u8]>>,
}
Expand Down Expand Up @@ -490,11 +493,24 @@ impl<'a> Socket<'a> {
dns_servers.push(*a).ok();
});

// Cleanup the NTP servers list, keeping only unicasts
let mut ntp_servers = Vec::new();

dhcp_repr
.ntp_servers
.iter()
.flatten()
.filter(|s| s.x_is_unicast())
.for_each(|a| {
ntp_servers.push(*a).ok();
});

let config = Config {
server,
address: Ipv4Cidr::new(dhcp_repr.your_ip, prefix_len),
router: dhcp_repr.router,
dns_servers,
ntp_servers,
packet: None,
};

Expand Down Expand Up @@ -598,6 +614,7 @@ impl<'a> Socket<'a> {
renew_duration: None,
rebind_duration: None,
dns_servers: None,
ntp_servers: None,
additional_options: self.outgoing_options,
};

Expand Down Expand Up @@ -753,6 +770,7 @@ impl<'a> Socket<'a> {
address: state.config.address,
router: state.config.router,
dns_servers: state.config.dns_servers.clone(),
ntp_servers: state.config.ntp_servers.clone(),
packet: self
.receive_packet_buffer
.as_deref()
Expand Down Expand Up @@ -901,6 +919,11 @@ mod test {
const DNS_IP_3: Ipv4Address = Ipv4Address::new(1, 1, 1, 3);
const DNS_IPS: &[Ipv4Address] = &[DNS_IP_1, DNS_IP_2, DNS_IP_3];

const NTP_IP_1: Ipv4Address = Ipv4Address::new(129, 6, 15, 28);
const NTP_IP_2: Ipv4Address = Ipv4Address::new(129, 6, 15, 29);
const NTP_IP_3: Ipv4Address = Ipv4Address::new(129, 6, 15, 30);
const NTP_IPS: &[Ipv4Address] = &[NTP_IP_1, NTP_IP_2, NTP_IP_3];

const MASK_24: Ipv4Address = Ipv4Address::new(255, 255, 255, 0);

const MY_MAC: EthernetAddress = EthernetAddress([0x02, 0x02, 0x02, 0x02, 0x02, 0x02]);
Expand Down Expand Up @@ -983,6 +1006,7 @@ mod test {
server_identifier: None,
parameter_request_list: None,
dns_servers: None,
ntp_servers: None,
max_size: None,
renew_duration: None,
rebind_duration: None,
Expand All @@ -993,7 +1017,7 @@ mod test {
const DHCP_DISCOVER: DhcpRepr = DhcpRepr {
message_type: DhcpMessageType::Discover,
client_identifier: Some(MY_MAC),
parameter_request_list: Some(&[1, 3, 6]),
parameter_request_list: Some(&[1, 3, 6, 42]),
max_size: Some(1432),
..DHCP_DEFAULT
};
Expand All @@ -1008,6 +1032,7 @@ mod test {
router: Some(SERVER_IP),
subnet_mask: Some(MASK_24),
dns_servers: Some(Vec::from_slice(DNS_IPS).unwrap()),
ntp_servers: Some(Vec::from_slice(NTP_IPS).unwrap()),
lease_duration: Some(1000),

..DHCP_DEFAULT
Expand All @@ -1021,7 +1046,7 @@ mod test {
max_size: Some(1432),

requested_ip: Some(MY_IP),
parameter_request_list: Some(&[1, 3, 6]),
parameter_request_list: Some(&[1, 3, 6, 42]),
..DHCP_DEFAULT
};

Expand All @@ -1035,6 +1060,7 @@ mod test {
router: Some(SERVER_IP),
subnet_mask: Some(MASK_24),
dns_servers: Some(Vec::from_slice(DNS_IPS).unwrap()),
ntp_servers: Some(Vec::from_slice(NTP_IPS).unwrap()),
lease_duration: Some(1000),

..DHCP_DEFAULT
Expand All @@ -1056,7 +1082,7 @@ mod test {
max_size: Some(1432),

requested_ip: None,
parameter_request_list: Some(&[1, 3, 6]),
parameter_request_list: Some(&[1, 3, 6, 42]),
..DHCP_DEFAULT
};

Expand All @@ -1068,7 +1094,7 @@ mod test {
max_size: Some(1432),

requested_ip: None,
parameter_request_list: Some(&[1, 3, 6]),
parameter_request_list: Some(&[1, 3, 6, 42]),
..DHCP_DEFAULT
};

Expand Down Expand Up @@ -1111,6 +1137,7 @@ mod test {
},
address: Ipv4Cidr::new(MY_IP, 24),
dns_servers: Vec::from_slice(DNS_IPS).unwrap(),
ntp_servers: Vec::from_slice(NTP_IPS).unwrap(),
router: Some(SERVER_IP),
packet: None,
},
Expand Down Expand Up @@ -1146,6 +1173,7 @@ mod test {
},
address: Ipv4Cidr::new(MY_IP, 24),
dns_servers: Vec::from_slice(DNS_IPS).unwrap(),
ntp_servers: Vec::from_slice(NTP_IPS).unwrap(),
router: Some(SERVER_IP),
packet: None,
}))
Expand Down Expand Up @@ -1184,6 +1212,7 @@ mod test {
},
address: Ipv4Cidr::new(MY_IP, 24),
dns_servers: Vec::from_slice(DNS_IPS).unwrap(),
ntp_servers: Vec::from_slice(NTP_IPS).unwrap(),
router: Some(SERVER_IP),
packet: None,
}))
Expand Down
78 changes: 78 additions & 0 deletions src/wire/dhcpv4.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ use crate::wire::{EthernetAddress, Ipv4Address};
pub const SERVER_PORT: u16 = 67;
pub const CLIENT_PORT: u16 = 68;
pub const MAX_DNS_SERVER_COUNT: usize = 3;
pub const MAX_NTP_SERVER_COUNT: usize = 3;

const DHCP_MAGIC_NUMBER: u32 = 0x63825363;

Expand Down Expand Up @@ -647,6 +648,8 @@ pub struct Repr<'a> {
pub parameter_request_list: Option<&'a [u8]>,
/// DNS servers
pub dns_servers: Option<Vec<Ipv4Address, MAX_DNS_SERVER_COUNT>>,
/// NTP servers (RFC 2132 §8.3)
pub ntp_servers: Option<Vec<Ipv4Address, MAX_NTP_SERVER_COUNT>>,
/// The maximum size dhcp packet the interface can receive
pub max_size: Option<u16>,
/// The DHCP IP lease duration, specified in seconds.
Expand Down Expand Up @@ -692,6 +695,10 @@ impl<'a> Repr<'a> {
len += 2;
len += dns_servers.iter().count() * core::mem::size_of::<u32>();
}
if let Some(ntp_servers) = &self.ntp_servers {
len += 2;
len += ntp_servers.iter().count() * core::mem::size_of::<u32>();
}
if let Some(list) = self.parameter_request_list {
len += list.len() + 2;
}
Expand Down Expand Up @@ -738,6 +745,7 @@ impl<'a> Repr<'a> {
let mut subnet_mask = None;
let mut parameter_request_list = None;
let mut dns_servers = None;
let mut ntp_servers = None;
let mut max_size = None;
let mut lease_duration = None;
let mut renew_duration = None;
Expand Down Expand Up @@ -804,6 +812,21 @@ impl<'a> Repr<'a> {
net_trace!("DHCP domain name servers contained invalid address");
}
}
(field::OPT_NTP_SERVERS, _) => {
let mut servers = Vec::new();
const IP_ADDR_BYTE_LEN: usize = 4;
let mut addrs = data.chunks_exact(IP_ADDR_BYTE_LEN);
for chunk in &mut addrs {
servers
.push(Ipv4Address::from_octets(chunk.try_into().unwrap()))
.ok();
}
ntp_servers = Some(servers);

if !addrs.remainder().is_empty() {
net_trace!("DHCP NTP servers contained invalid address");
}
}
_ => {}
}
}
Expand All @@ -826,6 +849,7 @@ impl<'a> Repr<'a> {
client_identifier,
parameter_request_list,
dns_servers,
ntp_servers,
max_size,
lease_duration,
renew_duration,
Expand Down Expand Up @@ -942,6 +966,24 @@ impl<'a> Repr<'a> {
})?;
}

if let Some(ntp_servers) = &self.ntp_servers {
const IP_SIZE: usize = core::mem::size_of::<u32>();
let mut servers = [0; MAX_NTP_SERVER_COUNT * IP_SIZE];

let data_len = ntp_servers
.iter()
.enumerate()
.inspect(|(i, ip)| {
servers[(i * IP_SIZE)..((i + 1) * IP_SIZE)].copy_from_slice(&ip.octets());
})
.count()
* IP_SIZE;
options.emit(DhcpOption {
kind: field::OPT_NTP_SERVERS,
data: &servers[..data_len],
})?;
}

for option in self.additional_options {
options.emit(*option)?;
}
Expand Down Expand Up @@ -1169,6 +1211,7 @@ mod test {
server_identifier: None,
parameter_request_list: None,
dns_servers: None,
ntp_servers: None,
max_size: None,
renew_duration: None,
rebind_duration: None,
Expand Down Expand Up @@ -1199,6 +1242,7 @@ mod test {
server_identifier: None,
parameter_request_list: Some(&[1, 3, 6, 42]),
dns_servers: None,
ntp_servers: None,
additional_options: &[],
}
}
Expand Down Expand Up @@ -1266,6 +1310,40 @@ mod test {
);
}

#[test]
fn test_emit_offer_ntp() {
let repr = {
let mut repr = offer_repr();
repr.ntp_servers = Some(
Vec::from_slice(&[
Ipv4Address::new(129, 6, 15, 28),
Ipv4Address::new(129, 6, 15, 29),
Ipv4Address::new(129, 6, 15, 30),
])
.unwrap(),
);
repr
};
let mut bytes = vec![0xa5; repr.buffer_len()];
let mut packet = Packet::new_unchecked(&mut bytes);
repr.emit(&mut packet).unwrap();

let packet = Packet::new_unchecked(&bytes);
let repr_parsed = Repr::parse(&packet).unwrap();

assert_eq!(
repr_parsed.ntp_servers,
Some(
Vec::from_slice(&[
Ipv4Address::new(129, 6, 15, 28),
Ipv4Address::new(129, 6, 15, 29),
Ipv4Address::new(129, 6, 15, 30),
])
.unwrap()
)
);
}

#[test]
fn test_emit_dhcp_option() {
static DATA: &[u8] = &[1, 3, 6];
Expand Down
3 changes: 2 additions & 1 deletion src/wire/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -280,7 +280,8 @@ pub use self::tcp::{
#[cfg(feature = "proto-dhcpv4")]
pub use self::dhcpv4::{
CLIENT_PORT as DHCP_CLIENT_PORT, DhcpOption, DhcpOptionWriter, Flags as DhcpFlags,
MAX_DNS_SERVER_COUNT as DHCP_MAX_DNS_SERVER_COUNT, MessageType as DhcpMessageType,
MAX_DNS_SERVER_COUNT as DHCP_MAX_DNS_SERVER_COUNT,
MAX_NTP_SERVER_COUNT as DHCP_MAX_NTP_SERVER_COUNT, MessageType as DhcpMessageType,
OpCode as DhcpOpCode, Packet as DhcpPacket, Repr as DhcpRepr, SERVER_PORT as DHCP_SERVER_PORT,
};

Expand Down
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