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Add suppor for DHCP maximum message size option.
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@MabezDev @whitequark
MabezDev authored and whitequark committed Nov 7, 2019
1 parent a67ee07 commit 8eb01ac
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Showing 2 changed files with 36 additions and 8 deletions.
2 changes: 1 addition & 1 deletion src/dhcp/clientv4.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -294,6 +294,7 @@ impl Client {
client_identifier: Some(mac),
server_identifier: None,
parameter_request_list: None,
max_size: Some(raw_socket.payload_recv_capacity() as u16),
dns_servers: None,
};
let mut send_packet = |iface, endpoint, dhcp_repr| {
Expand All @@ -305,7 +306,6 @@ impl Client {
match self.state {
ClientState::Discovering => {
self.next_egress = now + Duration::from_secs(DISCOVER_TIMEOUT);

let endpoint = IpEndpoint {
addr: Ipv4Address::BROADCAST.into(),
port: UDP_SERVER_PORT,
Expand Down
42 changes: 35 additions & 7 deletions src/wire/dhcpv4.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@ pub enum DhcpOption<'a> {
ServerIdentifier(Ipv4Address),
Router(Ipv4Address),
SubnetMask(Ipv4Address),
MaximumDhcpMessageSize(u16),
Other { kind: u8, data: &'a [u8] }
}

Expand Down Expand Up @@ -99,6 +100,9 @@ impl<'a> DhcpOption<'a> {
(field::OPT_SUBNET_MASK, 4) => {
option = DhcpOption::SubnetMask(Ipv4Address::from_bytes(data));
}
(field::OPT_MAX_DHCP_MESSAGE_SIZE, 2) => {
option = DhcpOption::MaximumDhcpMessageSize(u16::from_be_bytes([data[0], data[1]]));
}
(_, _) => {
option = DhcpOption::Other { kind: kind, data: data };
}
Expand All @@ -122,6 +126,9 @@ impl<'a> DhcpOption<'a> {
&DhcpOption::SubnetMask(ip) => {
2 + ip.as_bytes().len()
},
&DhcpOption::MaximumDhcpMessageSize(_) => {
4
}
&DhcpOption::Other { data, .. } => 2 + data.len()
}
}
Expand Down Expand Up @@ -167,6 +174,10 @@ impl<'a> DhcpOption<'a> {
buffer[0] = field::OPT_SUBNET_MASK;
buffer[2..6].copy_from_slice(mask.as_bytes());
}
&DhcpOption::MaximumDhcpMessageSize(size) => {
buffer[0] = field::OPT_MAX_DHCP_MESSAGE_SIZE;
buffer[2..4].copy_from_slice(&size.to_be_bytes()[..]);
}
&DhcpOption::Other { kind, data: provided } => {
buffer[0] = kind;
buffer[2..skip_length].copy_from_slice(provided);
Expand Down Expand Up @@ -661,6 +672,8 @@ pub struct Repr<'a> {
pub parameter_request_list: Option<&'a [u8]>,
/// DNS servers
pub dns_servers: Option<[Option<Ipv4Address>; 3]>,
/// The maximum size dhcp packet the interface can receive
pub max_size: Option<u16>,
}

impl<'a> Repr<'a> {
Expand All @@ -672,6 +685,7 @@ impl<'a> Repr<'a> {
if self.requested_ip.is_some() { len += 6; }
if self.client_identifier.is_some() { len += 9; }
if self.server_identifier.is_some() { len += 6; }
if self.max_size.is_some() { len += 4; }
if let Some(list) = self.parameter_request_list { len += list.len() + 2; }

len
Expand Down Expand Up @@ -710,6 +724,7 @@ impl<'a> Repr<'a> {
let mut subnet_mask = None;
let mut parameter_request_list = None;
let mut dns_servers = None;
let mut max_size = None;

let mut options = packet.options()?;
while options.len() > 0 {
Expand All @@ -736,6 +751,9 @@ impl<'a> Repr<'a> {
}
DhcpOption::SubnetMask(mask) => {
subnet_mask = Some(mask);
},
DhcpOption::MaximumDhcpMessageSize(size) => {
max_size = Some(size);
}
DhcpOption::Other {kind: field::OPT_PARAMETER_REQUEST_LIST, data} => {
parameter_request_list = Some(data);
Expand All @@ -760,7 +778,7 @@ impl<'a> Repr<'a> {
Ok(Repr {
transaction_id, client_hardware_address, client_ip, your_ip, server_ip, relay_agent_ip,
broadcast, requested_ip, server_identifier, router,
subnet_mask, client_identifier, parameter_request_list, dns_servers,
subnet_mask, client_identifier, parameter_request_list, dns_servers, max_size,
message_type: message_type?,
})
}
Expand Down Expand Up @@ -802,6 +820,9 @@ impl<'a> Repr<'a> {
if let Some(ip) = self.requested_ip {
let tmp = options; options = DhcpOption::RequestedIp(ip).emit(tmp);
}
if let Some(size) = self.max_size {
let tmp = options; options = DhcpOption::MaximumDhcpMessageSize(size).emit(tmp);
}
if let Some(list) = self.parameter_request_list {
let option = DhcpOption::Other{ kind: field::OPT_PARAMETER_REQUEST_LIST, data: list };
let tmp = options; options = option.emit(tmp);
Expand Down Expand Up @@ -837,7 +858,7 @@ mod test {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x63, 0x82, 0x53, 0x63,
0x35, 0x01, 0x01, 0x3d, 0x07, 0x01, 0x00, 0x0b, 0x82, 0x01, 0xfc, 0x42, 0x32, 0x04, 0x00, 0x00,
0x00, 0x00, 0x37, 0x04, 0x01, 0x03, 0x06, 0x2a, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x39, 0x2, 0x5, 0xdc, 0x37, 0x04, 0x01, 0x03, 0x06, 0x2a, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
];

static ACK_BYTES: &[u8] = &[
Expand Down Expand Up @@ -866,6 +887,7 @@ mod test {

const IP_NULL: Ipv4Address = Ipv4Address([0, 0, 0, 0]);
const CLIENT_MAC: EthernetAddress = EthernetAddress([0x0, 0x0b, 0x82, 0x01, 0xfc, 0x42]);
const DHCP_SIZE: u16 = 1500;

#[test]
fn test_deconstruct_discover() {
Expand All @@ -883,18 +905,22 @@ mod test {
assert_eq!(packet.relay_agent_ip(), IP_NULL);
assert_eq!(packet.client_hardware_address(), CLIENT_MAC);
let options = packet.options().unwrap();
assert_eq!(options.len(), 3 + 9 + 6 + 6 + 1 + 7);
assert_eq!(options.len(), 3 + 9 + 6 + 4 + 6 + 1 + 7);

let (options, message_type) = DhcpOption::parse(options).unwrap();
assert_eq!(message_type, DhcpOption::MessageType(MessageType::Discover));
assert_eq!(options.len(), 9 + 6 + 6 + 1 + 7);
assert_eq!(options.len(), 9 + 6 + 4 + 6 + 1 + 7);

let (options, client_id) = DhcpOption::parse(options).unwrap();
assert_eq!(client_id, DhcpOption::ClientIdentifier(CLIENT_MAC));
assert_eq!(options.len(), 6 + 6 + 1 + 7);
assert_eq!(options.len(), 6 + 4 + 6 + 1 + 7);

let (options, client_id) = DhcpOption::parse(options).unwrap();
assert_eq!(client_id, DhcpOption::RequestedIp(IP_NULL));
assert_eq!(options.len(), 4 + 6 + 1 + 7);

let (options, msg_size) = DhcpOption::parse(options).unwrap();
assert_eq!(msg_size, DhcpOption::MaximumDhcpMessageSize(DHCP_SIZE));
assert_eq!(options.len(), 6 + 1 + 7);

let (options, client_id) = DhcpOption::parse(options).unwrap();
Expand All @@ -910,7 +936,7 @@ mod test {

#[test]
fn test_construct_discover() {
let mut bytes = vec![0xa5; 272];
let mut bytes = vec![0xa5; 276];
let mut packet = Packet::new_unchecked(&mut bytes);
packet.set_magic_number(MAGIC_COOKIE);
packet.set_sname_and_boot_file_to_zero();
Expand All @@ -932,6 +958,7 @@ mod test {
let tmp = options; options = DhcpOption::MessageType(MessageType::Discover).emit(tmp);
let tmp = options; options = DhcpOption::ClientIdentifier(CLIENT_MAC).emit(tmp);
let tmp = options; options = DhcpOption::RequestedIp(IP_NULL).emit(tmp);
let tmp = options; options = DhcpOption::MaximumDhcpMessageSize(DHCP_SIZE).emit(tmp);
let option = DhcpOption::Other {
kind: field::OPT_PARAMETER_REQUEST_LIST, data: &[1, 3, 6, 42],
};
Expand All @@ -940,7 +967,7 @@ mod test {
}

let packet = &mut packet.into_inner()[..];
for byte in &mut packet[265..272] {
for byte in &mut packet[269..276] {
*byte = 0; // padding bytes
}

Expand All @@ -959,6 +986,7 @@ mod test {
subnet_mask: None,
relay_agent_ip: IP_NULL,
broadcast: false,
max_size: Some(DHCP_SIZE),
requested_ip: Some(IP_NULL),
client_identifier: Some(CLIENT_MAC),
server_identifier: None,
Expand Down

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