430 lines
16 KiB
Rust
430 lines
16 KiB
Rust
use crate::{Result, Error};
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use crate::wire::{IpVersion, IpProtocol, IpEndpoint, IpAddress,
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Ipv4Cidr, Ipv4Address, Ipv4Packet, Ipv4Repr,
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UdpPacket, UdpRepr,
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DhcpPacket, DhcpRepr, DhcpMessageType};
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use crate::wire::dhcpv4::field as dhcpv4_field;
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use crate::socket::{SocketSet, SocketHandle, RawSocket, RawSocketBuffer};
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use crate::phy::{Device, ChecksumCapabilities};
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use crate::iface::EthernetInterface as Interface;
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use crate::time::{Instant, Duration};
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use super::{UDP_SERVER_PORT, UDP_CLIENT_PORT};
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const DISCOVER_TIMEOUT: u64 = 10;
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const REQUEST_TIMEOUT: u64 = 1;
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const REQUEST_RETRIES: u16 = 15;
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const RENEW_INTERVAL: u64 = 60;
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const RENEW_RETRIES: u16 = 3;
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const PARAMETER_REQUEST_LIST: &[u8] = &[
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dhcpv4_field::OPT_SUBNET_MASK,
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dhcpv4_field::OPT_ROUTER,
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dhcpv4_field::OPT_DOMAIN_NAME_SERVER,
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];
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/// IPv4 configuration data returned by `client.poll()`
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#[derive(Debug)]
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pub struct Config {
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pub address: Option<Ipv4Cidr>,
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pub router: Option<Ipv4Address>,
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pub dns_servers: [Option<Ipv4Address>; 3],
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}
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#[derive(Debug)]
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struct RequestState {
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retry: u16,
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endpoint_ip: Ipv4Address,
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server_identifier: Ipv4Address,
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requested_ip: Ipv4Address,
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}
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#[derive(Debug)]
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struct RenewState {
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retry: u16,
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endpoint_ip: Ipv4Address,
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server_identifier: Ipv4Address,
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}
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#[derive(Debug)]
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enum ClientState {
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/// Discovering the DHCP server
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Discovering,
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/// Requesting an address
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Requesting(RequestState),
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/// Having an address, refresh it periodically
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Renew(RenewState),
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}
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pub struct Client {
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state: ClientState,
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raw_handle: SocketHandle,
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/// When to send next request
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next_egress: Instant,
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transaction_id: u32,
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}
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/// DHCP client with a RawSocket.
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///
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/// To provide memory for the dynamic IP address, configure your
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/// `Interface` with one of `ip_addrs` and the `ipv4_gateway` being
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/// `Ipv4Address::UNSPECIFIED`. You must also assign this `0.0.0.0/0`
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/// while the client's state is `Discovering`. Hence, the `poll()`
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/// method returns a corresponding `Config` struct in this case.
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///
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/// You must call `dhcp_client.poll()` after `iface.poll()` to send
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/// and receive DHCP packets.
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impl Client {
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/// # Usage
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/// ```rust
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/// use smoltcp::socket::{SocketSet, RawSocketBuffer, RawPacketMetadata};
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/// use smoltcp::dhcp::Dhcpv4Client;
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/// use smoltcp::time::Instant;
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///
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/// let mut sockets = SocketSet::new(vec![]);
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/// let dhcp_rx_buffer = RawSocketBuffer::new(
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/// [RawPacketMetadata::EMPTY; 1],
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/// vec![0; 600]
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/// );
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/// let dhcp_tx_buffer = RawSocketBuffer::new(
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/// [RawPacketMetadata::EMPTY; 1],
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/// vec![0; 600]
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/// );
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/// let mut dhcp = Dhcpv4Client::new(
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/// &mut sockets,
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/// dhcp_rx_buffer, dhcp_tx_buffer,
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/// Instant::now()
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/// );
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/// ```
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pub fn new<'a, 'b, 'c>(sockets: &mut SocketSet<'a, 'b, 'c>, rx_buffer: RawSocketBuffer<'b, 'c>, tx_buffer: RawSocketBuffer<'b, 'c>, now: Instant) -> Self
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where 'b: 'c,
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{
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let raw_socket = RawSocket::new(IpVersion::Ipv4, IpProtocol::Udp, rx_buffer, tx_buffer);
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let raw_handle = sockets.add(raw_socket);
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Client {
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state: ClientState::Discovering,
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raw_handle,
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next_egress: now,
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transaction_id: 1,
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}
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}
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/// When to send next packet
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///
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/// Useful for suspending execution after polling.
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pub fn next_poll(&self, now: Instant) -> Duration {
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self.next_egress - now
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}
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/// Process incoming packets on the contained RawSocket, and send
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/// DHCP requests when timeouts are ready.
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///
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/// Applying the obtained network configuration is left to the
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/// user.
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///
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/// A Config can be returned from any valid DHCP reply. The client
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/// performs no bookkeeping on configuration or their changes.
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pub fn poll<DeviceT>(&mut self,
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iface: &mut Interface<DeviceT>, sockets: &mut SocketSet,
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now: Instant
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) -> Result<Option<Config>>
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where
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DeviceT: for<'d> Device<'d>,
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{
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let checksum_caps = iface.device().capabilities().checksum;
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let mut raw_socket = sockets.get::<RawSocket>(self.raw_handle);
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// Process incoming
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let config = {
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match raw_socket.recv()
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.and_then(|packet| parse_udp(packet, &checksum_caps)) {
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Ok((IpEndpoint {
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addr: IpAddress::Ipv4(src_ip),
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port: UDP_SERVER_PORT,
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}, IpEndpoint {
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addr: _,
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port: UDP_CLIENT_PORT,
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}, payload)) =>
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self.ingress(iface, now, payload, &src_ip),
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Ok(_) =>
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return Err(Error::Unrecognized),
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Err(Error::Exhausted) =>
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None,
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Err(e) =>
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return Err(e),
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}
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};
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if config.is_some() {
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// Return a new config immediately so that addresses can
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// be configured that are required by egress().
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Ok(config)
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} else {
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// Send requests
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if raw_socket.can_send() && now >= self.next_egress {
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self.egress(iface, &mut *raw_socket, &checksum_caps, now)
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} else {
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Ok(None)
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}
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}
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}
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fn ingress<DeviceT>(&mut self,
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iface: &mut Interface<DeviceT>, now: Instant,
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data: &[u8], src_ip: &Ipv4Address
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) -> Option<Config>
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where
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DeviceT: for<'d> Device<'d>,
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{
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let dhcp_packet = match DhcpPacket::new_checked(data) {
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Ok(dhcp_packet) => dhcp_packet,
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Err(e) => {
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net_debug!("DHCP invalid pkt from {}: {:?}", src_ip, e);
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return None;
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}
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};
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let dhcp_repr = match DhcpRepr::parse(&dhcp_packet) {
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Ok(dhcp_repr) => dhcp_repr,
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Err(e) => {
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net_debug!("DHCP error parsing pkt from {}: {:?}", src_ip, e);
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return None;
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}
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};
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let mac = iface.ethernet_addr();
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if dhcp_repr.client_hardware_address != mac { return None }
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if dhcp_repr.transaction_id != self.transaction_id { return None }
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let server_identifier = match dhcp_repr.server_identifier {
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Some(server_identifier) => server_identifier,
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None => return None,
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};
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net_debug!("DHCP recv {:?} from {} ({})", dhcp_repr.message_type, src_ip, server_identifier);
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// once we receive the ack, we can pass the config to the user
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let config = if dhcp_repr.message_type == DhcpMessageType::Ack {
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let address = dhcp_repr.subnet_mask
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.and_then(|mask| IpAddress::Ipv4(mask).to_prefix_len())
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.map(|prefix_len| Ipv4Cidr::new(dhcp_repr.your_ip, prefix_len));
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let router = dhcp_repr.router;
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let dns_servers = dhcp_repr.dns_servers
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.unwrap_or([None; 3]);
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Some(Config { address, router, dns_servers })
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} else {
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None
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};
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match self.state {
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ClientState::Discovering
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if dhcp_repr.message_type == DhcpMessageType::Offer =>
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{
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self.next_egress = now;
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let r_state = RequestState {
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retry: 0,
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endpoint_ip: *src_ip,
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server_identifier,
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requested_ip: dhcp_repr.your_ip // use the offered ip
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};
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Some(ClientState::Requesting(r_state))
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}
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ClientState::Requesting(ref r_state)
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if dhcp_repr.message_type == DhcpMessageType::Ack &&
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server_identifier == r_state.server_identifier =>
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{
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self.next_egress = now + Duration::from_secs(RENEW_INTERVAL);
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let p_state = RenewState {
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retry: 0,
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endpoint_ip: *src_ip,
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server_identifier,
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};
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Some(ClientState::Renew(p_state))
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}
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ClientState::Renew(ref mut p_state)
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if dhcp_repr.message_type == DhcpMessageType::Ack &&
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server_identifier == p_state.server_identifier =>
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{
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self.next_egress = now + Duration::from_secs(RENEW_INTERVAL);
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p_state.retry = 0;
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None
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}
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_ => None
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}.map(|new_state| self.state = new_state);
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config
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}
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fn egress<DeviceT: for<'d> Device<'d>>(&mut self, iface: &mut Interface<DeviceT>, raw_socket: &mut RawSocket, checksum_caps: &ChecksumCapabilities, now: Instant) -> Result<Option<Config>> {
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// Reset after maximum amount of retries
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let retries_exceeded = match self.state {
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ClientState::Requesting(ref mut r_state) if r_state.retry >= REQUEST_RETRIES => {
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net_debug!("DHCP request retries exceeded, restarting discovery");
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true
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}
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ClientState::Renew(ref mut r_state) if r_state.retry >= RENEW_RETRIES => {
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net_debug!("DHCP renew retries exceeded, restarting discovery");
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true
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}
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_ => false
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};
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if retries_exceeded {
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self.reset(now);
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// Return a config now so that user code assigns the
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// 0.0.0.0/0 address, which will be used sending a DHCP
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// discovery packet in the next call to egress().
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return Ok(Some(Config {
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address: Some(Ipv4Cidr::new(Ipv4Address::UNSPECIFIED, 0)),
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router: None,
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dns_servers: [None; 3],
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}));
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}
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// Prepare sending next packet
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self.transaction_id += 1;
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let mac = iface.ethernet_addr();
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let mut dhcp_repr = DhcpRepr {
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message_type: DhcpMessageType::Discover,
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transaction_id: self.transaction_id,
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client_hardware_address: mac,
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client_ip: Ipv4Address::UNSPECIFIED,
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your_ip: Ipv4Address::UNSPECIFIED,
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server_ip: Ipv4Address::UNSPECIFIED,
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router: None,
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subnet_mask: None,
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relay_agent_ip: Ipv4Address::UNSPECIFIED,
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broadcast: true,
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requested_ip: None,
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client_identifier: Some(mac),
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server_identifier: None,
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parameter_request_list: None,
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max_size: Some(raw_socket.payload_recv_capacity() as u16),
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dns_servers: None,
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};
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let mut send_packet = |iface, endpoint, dhcp_repr| {
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send_packet(iface, raw_socket, &endpoint, &dhcp_repr, checksum_caps)
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.map(|()| None)
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};
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match self.state {
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ClientState::Discovering => {
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self.next_egress = now + Duration::from_secs(DISCOVER_TIMEOUT);
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let endpoint = IpEndpoint {
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addr: Ipv4Address::BROADCAST.into(),
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port: UDP_SERVER_PORT,
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};
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net_trace!("DHCP send discover to {}: {:?}", endpoint, dhcp_repr);
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send_packet(iface, endpoint, dhcp_repr)
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}
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ClientState::Requesting(ref mut r_state) => {
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r_state.retry += 1;
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self.next_egress = now + Duration::from_secs(REQUEST_TIMEOUT);
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let endpoint = IpEndpoint {
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addr: Ipv4Address::BROADCAST.into(),
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port: UDP_SERVER_PORT,
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};
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dhcp_repr.message_type = DhcpMessageType::Request;
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dhcp_repr.broadcast = false;
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dhcp_repr.requested_ip = Some(r_state.requested_ip);
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dhcp_repr.server_identifier = Some(r_state.server_identifier);
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dhcp_repr.parameter_request_list = Some(PARAMETER_REQUEST_LIST);
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net_trace!("DHCP send request to {} = {:?}", endpoint, dhcp_repr);
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send_packet(iface, endpoint, dhcp_repr)
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}
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ClientState::Renew(ref mut p_state) => {
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p_state.retry += 1;
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self.next_egress = now + Duration::from_secs(RENEW_INTERVAL);
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let endpoint = IpEndpoint {
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addr: p_state.endpoint_ip.into(),
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port: UDP_SERVER_PORT,
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};
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let client_ip = iface.ipv4_addr().unwrap_or(Ipv4Address::UNSPECIFIED);
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dhcp_repr.message_type = DhcpMessageType::Request;
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dhcp_repr.client_ip = client_ip;
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dhcp_repr.broadcast = false;
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net_trace!("DHCP send renew to {}: {:?}", endpoint, dhcp_repr);
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send_packet(iface, endpoint, dhcp_repr)
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}
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}
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}
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/// Reset state and restart discovery phase.
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///
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/// Use this to speed up acquisition of an address in a new
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/// network if a link was down and it is now back up.
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///
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/// You *must* configure a `0.0.0.0` address on your interface
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/// before the next call to `poll()`!
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pub fn reset(&mut self, now: Instant) {
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net_trace!("DHCP reset");
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self.state = ClientState::Discovering;
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self.next_egress = now;
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}
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}
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fn send_packet<DeviceT: for<'d> Device<'d>>(iface: &mut Interface<DeviceT>, raw_socket: &mut RawSocket, endpoint: &IpEndpoint, dhcp_repr: &DhcpRepr, checksum_caps: &ChecksumCapabilities) -> Result<()> {
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let mut dhcp_payload_buf = [0; 320];
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assert!(dhcp_repr.buffer_len() <= dhcp_payload_buf.len());
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let dhcp_payload = &mut dhcp_payload_buf[0..dhcp_repr.buffer_len()];
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{
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let mut dhcp_packet = DhcpPacket::new_checked(&mut dhcp_payload[..])?;
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dhcp_repr.emit(&mut dhcp_packet)?;
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}
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let udp_repr = UdpRepr {
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src_port: UDP_CLIENT_PORT,
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dst_port: endpoint.port,
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payload: dhcp_payload,
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};
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let src_addr = iface.ipv4_addr().unwrap();
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let dst_addr = match endpoint.addr {
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IpAddress::Ipv4(addr) => addr,
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_ => return Err(Error::Illegal),
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};
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let ipv4_repr = Ipv4Repr {
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src_addr,
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dst_addr,
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protocol: IpProtocol::Udp,
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payload_len: udp_repr.buffer_len(),
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hop_limit: 64,
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};
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let mut packet = raw_socket.send(
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ipv4_repr.buffer_len() + udp_repr.buffer_len()
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)?;
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{
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let mut ipv4_packet = Ipv4Packet::new_unchecked(&mut packet);
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ipv4_repr.emit(&mut ipv4_packet, &checksum_caps);
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}
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{
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let mut udp_packet = UdpPacket::new_unchecked(
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&mut packet[ipv4_repr.buffer_len()..]
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);
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udp_repr.emit(&mut udp_packet,
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&src_addr.into(), &dst_addr.into(),
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checksum_caps);
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}
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Ok(())
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}
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fn parse_udp<'a>(data: &'a [u8], checksum_caps: &ChecksumCapabilities) -> Result<(IpEndpoint, IpEndpoint, &'a [u8])> {
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let ipv4_packet = Ipv4Packet::new_checked(data)?;
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let ipv4_repr = Ipv4Repr::parse(&ipv4_packet, &checksum_caps)?;
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let udp_packet = UdpPacket::new_checked(ipv4_packet.payload())?;
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let udp_repr = UdpRepr::parse(
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&udp_packet,
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&ipv4_repr.src_addr.into(), &ipv4_repr.dst_addr.into(),
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checksum_caps
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)?;
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let src = IpEndpoint {
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addr: ipv4_repr.src_addr.into(),
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port: udp_repr.src_port,
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};
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let dst = IpEndpoint {
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addr: ipv4_repr.dst_addr.into(),
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port: udp_repr.dst_port,
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};
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let data = udp_repr.payload;
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Ok((src, dst, data))
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}
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