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|
use std::{
io::{Result, Write},
net::Ipv4Addr,
};
use crate::wire;
const MAGIC_COOKIE: [u8; 4] = [0x63, 0x82, 0x53, 0x63];
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
pub enum BootOp {
#[default]
Request,
Reply,
}
impl BootOp {
pub const OP_REQUEST: u8 = 1;
pub const OP_REPLY: u8 = 2;
}
impl From<BootOp> for u8 {
fn from(value: BootOp) -> Self {
match value {
BootOp::Request => BootOp::OP_REQUEST,
BootOp::Reply => BootOp::OP_REPLY,
}
}
}
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
pub enum HardwareType {
#[default]
Ethernet,
}
impl HardwareType {
pub const TYPE_ETHER: u8 = 1;
pub const LEN_ETHER: u8 = 6;
pub fn hardware_len(&self) -> u8 {
match self {
HardwareType::Ethernet => Self::LEN_ETHER,
}
}
}
impl From<HardwareType> for u8 {
fn from(value: HardwareType) -> Self {
match value {
HardwareType::Ethernet => HardwareType::TYPE_ETHER,
}
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum DhcpMessageType {
Ack,
}
impl DhcpMessageType {
pub const CODE_ACK: u8 = 5;
pub fn code(&self) -> u8 {
match self {
DhcpMessageType::Ack => Self::CODE_ACK,
}
}
}
#[derive(Debug, Clone)]
pub enum DhcpOption {
Pad,
End,
MessageType(DhcpMessageType),
ServerIdentifier(Ipv4Addr),
VendorClassIdentifier(String),
TftpServerName(String),
TftpFileName(String),
UserClassInformation(String),
ClientMachineIdentifier(String),
Unknown { code: u8, data: Vec<u8> },
}
impl DhcpOption {
pub const CODE_PAD: u8 = 0;
pub const CODE_END: u8 = 255;
pub const CODE_DHCP_MESSAGE_TYPE: u8 = 53;
pub const CODE_DHCP_SERVER_IDENTIFIER: u8 = 54;
pub const CODE_VENDOR_CLASS_IDENTIFIER: u8 = 60;
pub const CODE_TFTP_SERVER_NAME: u8 = 66;
pub const CODE_TFTP_FILE_NAME: u8 = 67;
pub const CODE_USER_CLASS_INFORMATION: u8 = 77;
pub const CODE_CLIENT_MACHINE_IDENTIFIER: u8 = 97;
pub fn code(&self) -> u8 {
match self {
DhcpOption::Pad => Self::CODE_PAD,
DhcpOption::End => Self::CODE_END,
DhcpOption::MessageType(_) => Self::CODE_DHCP_MESSAGE_TYPE,
DhcpOption::ServerIdentifier(_) => Self::CODE_DHCP_SERVER_IDENTIFIER,
DhcpOption::VendorClassIdentifier(_) => Self::CODE_VENDOR_CLASS_IDENTIFIER,
DhcpOption::TftpServerName(_) => Self::CODE_TFTP_SERVER_NAME,
DhcpOption::TftpFileName(_) => Self::CODE_TFTP_FILE_NAME,
DhcpOption::UserClassInformation(_) => Self::CODE_USER_CLASS_INFORMATION,
DhcpOption::ClientMachineIdentifier(_) => Self::CODE_CLIENT_MACHINE_IDENTIFIER,
DhcpOption::Unknown { code, .. } => *code,
}
}
}
#[derive(Debug)]
pub struct DhcpPacket {
pub op: BootOp,
pub htype: HardwareType,
pub xid: u32,
pub secs: u16,
pub flags: u16,
pub ciaddr: Ipv4Addr,
pub yiaddr: Ipv4Addr,
pub siaddr: Ipv4Addr,
pub giaddr: Ipv4Addr,
pub chaddr: [u8; 16],
// server host name
pub sname: Option<String>,
// boot file name
pub file: Option<String>,
pub options: Vec<DhcpOption>,
}
impl Default for DhcpPacket {
fn default() -> Self {
Self {
op: Default::default(),
htype: Default::default(),
xid: Default::default(),
secs: Default::default(),
flags: Default::default(),
ciaddr: Ipv4Addr::UNSPECIFIED,
yiaddr: Ipv4Addr::UNSPECIFIED,
siaddr: Ipv4Addr::UNSPECIFIED,
giaddr: Ipv4Addr::UNSPECIFIED,
chaddr: Default::default(),
sname: Default::default(),
file: Default::default(),
options: Default::default(),
}
}
}
pub fn write_packet<W: Write>(mut writer: W, packet: &DhcpPacket) -> Result<()> {
wire::write_u8(&mut writer, u8::from(packet.op))?;
wire::write_u8(&mut writer, u8::from(packet.htype))?;
wire::write_u8(&mut writer, packet.htype.hardware_len())?;
wire::write_u8(&mut writer, 0)?; // hops
wire::write_u32(&mut writer, packet.xid)?;
wire::write_u16(&mut writer, packet.secs)?;
wire::write_u16(&mut writer, packet.flags)?;
wire::write_ipv4(&mut writer, packet.ciaddr)?;
wire::write_ipv4(&mut writer, packet.yiaddr)?;
wire::write_ipv4(&mut writer, packet.siaddr)?;
wire::write_ipv4(&mut writer, packet.giaddr)?;
wire::write(&mut writer, &packet.chaddr)?;
match &packet.sname {
Some(name) => wire::write_null_terminated_string(&mut writer, &name)?,
None => wire::write_null_terminated_string(&mut writer, "")?,
};
match &packet.file {
Some(name) => wire::write_null_terminated_string(&mut writer, &name)?,
None => wire::write_null_terminated_string(&mut writer, "")?,
};
wire::write(&mut writer, &MAGIC_COOKIE)?;
for option in &packet.options {
write_option(&mut writer, option)?;
}
write_option(&mut writer, &DhcpOption::End)?;
Ok(())
}
pub fn write_option<W: Write>(mut writer: W, option: &DhcpOption) -> Result<()> {
wire::write_u8(&mut writer, option.code())?;
match option {
DhcpOption::Pad | DhcpOption::End => {}
DhcpOption::MessageType(t) => {
wire::write_u8(&mut writer, 1)?;
wire::write_u8(&mut writer, t.code())?;
}
DhcpOption::ServerIdentifier(ip) => {
wire::write_u8(&mut writer, 4)?;
wire::write_ipv4(&mut writer, *ip)?;
}
DhcpOption::VendorClassIdentifier(vendor_class) => {
write_option_len_prefixed_string(&mut writer, &vendor_class)?
}
DhcpOption::TftpServerName(name) => write_option_len_prefixed_string(&mut writer, &name)?,
DhcpOption::TftpFileName(name) => write_option_len_prefixed_string(&mut writer, &name)?,
DhcpOption::UserClassInformation(user_class) => {
write_option_len_prefixed_string(&mut writer, &user_class)?
}
DhcpOption::ClientMachineIdentifier(identifier) => {
write_option_len_prefixed_string(&mut writer, &identifier)?
}
DhcpOption::Unknown { data, .. } => {
wire::write_u8(&mut writer, u8::try_from(data.len()).unwrap())?;
wire::write(&mut writer, &data)?;
}
}
Ok(())
}
fn write_option_len_prefixed_string<W: Write>(mut writer: W, s: &str) -> Result<()> {
wire::write_u8(&mut writer, u8::try_from(s.len()).unwrap())?;
wire::write(&mut writer, s.as_bytes())
}
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