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parse server name and file name

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This commit is contained in:
fuckwit 2023-05-22 22:43:16 +02:00
parent e189168144
commit e0cc79198f
1 changed files with 58 additions and 8 deletions
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66
src/lib.rs
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@ -1,7 +1,8 @@
#![allow(unused)]
use std::{net::Ipv4Addr, path::Path};
use nom::{
bytes::complete::take,
bytes::complete::{take, take_until},
number::complete::{be_u16, be_u32, be_u8},
IResult,
};
@ -14,15 +15,18 @@ struct DhcpMessage<'a> {
hops: u8,
transaction_id: u32,
seconds: u16,
flags: u16,
flags: Flags,
client_address: Ipv4Addr,
server_address: Ipv4Addr,
gateway_address: Ipv4Addr,
client_hardware_address: &'a [u8],
server_hostname: &'a str,
boot_file_name: &'a Path,
server_name: &'a str,
file_name: &'a Path,
}
#[derive(Debug)]
struct Flags(u16);
#[derive(Debug)]
enum Operation {
Request = 1,
@ -61,6 +65,10 @@ fn parse_dhcp_operation(i: &[u8]) -> IResult<&[u8], Operation> {
be_u8(i).map(|(i, v)| (i, v.into()))
}
fn parse_dhcp_flags(i: &[u8]) -> IResult<&[u8], Flags> {
be_u16(i).map(|(i, v)| (i, Flags(v)))
}
fn parse_dhcp_hardware_type(i: &[u8]) -> IResult<&[u8], HardwareType> {
be_u8(i).map(|(i, v)| (i, v.into()))
}
@ -71,6 +79,28 @@ fn parse_ipv4_address(i: &[u8]) -> IResult<&[u8], Ipv4Addr> {
Ok((i, ip))
}
fn parse_client_hardware_address(i: &[u8], hardware_address_length: u8) -> IResult<&[u8], &[u8]> {
let (i, val) = take(hardware_address_length)(i)?;
let (i, _padding) = take(0x10 - hardware_address_length)(i)?;
Ok((i, val))
}
fn parse_server_name(i: &[u8]) -> IResult<&[u8], &str> {
let (i, val) = take(64usize)(i)?;
let nullbyte_position = val.iter().position(|v| *v == b'\0').unwrap_or(64);
let val = unsafe { std::str::from_utf8_unchecked(&val[..nullbyte_position]) };
Ok((i, val))
}
fn parse_file(i: &[u8]) -> IResult<&[u8], &Path> {
let (i, val) = take(128usize)(i)?;
let nullbyte_position = val.iter().position(|v| *v == b'\0').unwrap_or(128);
let val = unsafe { std::str::from_utf8_unchecked(&val[..nullbyte_position]) };
Ok((i, Path::new(val)))
}
fn parse_dhcp_packet(packet: &[u8]) -> IResult<&[u8], DhcpMessage> {
let (packet, operation) = parse_dhcp_operation(packet)?;
let (packet, hardware_type) = parse_dhcp_hardware_type(packet)?;
@ -78,11 +108,16 @@ fn parse_dhcp_packet(packet: &[u8]) -> IResult<&[u8], DhcpMessage> {
let (packet, hops) = be_u8(packet)?;
let (packet, transaction_id) = be_u32(packet)?;
let (packet, seconds) = be_u16(packet)?;
let (packet, flags) = be_u16(packet)?;
let (packet, flags) = parse_dhcp_flags(packet)?;
let (packet, client_address) = parse_ipv4_address(packet)?;
let (packet, server_address) = parse_ipv4_address(packet)?;
let (packet, gateway_address) = parse_ipv4_address(packet)?;
let (packet, client_hardware_address) = take(6usize)(packet)?;
let (packet, client_hardware_address) =
parse_client_hardware_address(packet, hardware_address_length)?;
let potential_options = packet;
let (packet, server_name) = parse_server_name(packet)?;
let (packet, file_name) = parse_file(packet)?;
Ok((
packet,
@ -98,8 +133,8 @@ fn parse_dhcp_packet(packet: &[u8]) -> IResult<&[u8], DhcpMessage> {
server_address,
gateway_address,
client_hardware_address,
server_hostname: "",
boot_file_name: Path::new(""),
server_name,
file_name,
},
))
}
@ -110,6 +145,21 @@ mod tests {
static DHCP_PACKET2: &'static [u8] = &[
0x01, 0x01, 0x06, 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02, 0x00, 0x01, 0x7f, 0x00, 0x00,
0x01, 0x7f, 0x00, 0x00, 0x01, 0x7f, 0x00, 0x00, 0x01, 0x54, 0x05, 0xdb, 0xa6, 0x96, 0xd0,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //CHADDR padding
0x49, 0x20, 0x62, 0x69, 0x6D, 0x73, 0x20, 0x31, 0x20, 0x44, 0x48, 0x43, 0x50, 0x20, 0x53,
0x65, 0x72, 0x76, 0x65, 0x72, 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, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, // server name with padding
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, 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, 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, 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, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // file with padding
];
#[test]