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Fix infinite loop in DNS parsing #38

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merged 2 commits into from
Dec 3, 2024
Merged

Fix infinite loop in DNS parsing #38

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dc1af63
cleanup(dns): Condenses MAC parsing
dgmcdona Nov 29, 2024
12d5d19
fix(dns): infinite loop in DNS parsing code
dgmcdona Nov 29, 2024
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78 changes: 38 additions & 40 deletions src/decoders/dns.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,10 @@ use log::{error, warn};
use nom::{
bits,
bytes::complete::take,
combinator::{map, verify},
multi::many0,
number::complete::{be_u128, be_u16, be_u32, be_u8, le_u32},
sequence::tuple,
};
use std::{
mem::size_of,
Expand Down Expand Up @@ -268,42 +271,44 @@ fn parse_svcb_alpn(dns_data: &[u8]) -> nom::IResult<&[u8], String> {

/// Parse the IPs
fn parse_svcb_ip(data: &[u8]) -> nom::IResult<&[u8], String> {
const IPV4: u16 = 4;
const IPV6: u16 = 6;

let mut dns_data = data;
let mut ipv4_hint = String::from("ipv4 hint:");
let mut ipv6_hint = String::from("ipv6 hint:");

let mut ipv4_addrs = vec![];
let mut ipv6_addrs = vec![];

// IPs can either be IPv4 or/and IPv6
while !dns_data.is_empty() {
let (remaining_dns_data, ip_type) = take(size_of::<u16>())(dns_data)?;
let (_, ip_version) = be_u16(ip_type)?;
let (remaining_dns_data, (ip_version, ip_size)) =
tuple((verify(be_u16, |val| *val == IPV4 || *val == IPV6), be_u16))(dns_data)?;

let (remaining_dns_data, total_ip_size) = take(size_of::<u16>())(remaining_dns_data)?;
let (_, ip_size) = be_u16(total_ip_size)?;
let (remaining_dns_data, ip_data) = take(ip_size)(remaining_dns_data)?;

let (remaining_dns_data, mut ip_data) = take(ip_size)(remaining_dns_data)?;
dns_data = remaining_dns_data;
let ipv4 = 4;
let ipv6 = 6;

// There can be multiple IPs
while !ip_data.is_empty() {
if ip_version == ipv4 {
let (remaining_ip_data, ipv4_data) = take(size_of::<u32>())(ip_data)?;
ip_data = remaining_ip_data;

let (_, ip) = be_u32(ipv4_data)?;
let ip_addr = Ipv4Addr::from(ip);
ipv4_hint = format!("{}{},", ipv4_hint, ip_addr);
} else if ip_version == ipv6 {
let (remaining_ip_data, ipv6_data) = take(size_of::<u128>())(ip_data)?;
ip_data = remaining_ip_data;

let (_, ip) = be_u128(ipv6_data)?;
let ip_addr = Ipv6Addr::from(ip);
ipv6_hint = format!("{}{},", ipv6_hint, ip_addr);
match ip_version {
IPV4 => {
let (_, mut addrs) =
many0(map(be_u32, |raw| Ipv4Addr::from(raw).to_string()))(ip_data)?;
ipv4_addrs.append(&mut addrs);
}
}
IPV6 => {
let (_, mut addrs) =
many0(map(be_u128, |raw| Ipv6Addr::from(raw).to_string()))(ip_data)?;
ipv6_addrs.append(&mut addrs);
}
_ => {}
};
}
let message = format!("{} {}", ipv4_hint, ipv6_hint);

let message = format!(
"ipv4 hint:{}, ipv6 hint:{}",
ipv4_addrs.join(","),
ipv6_addrs.join(",")
);
Ok((dns_data, message))
}

Expand Down Expand Up @@ -336,17 +341,10 @@ pub(crate) fn get_dns_mac_addr(data: &str) -> String {

/// Parse the MAC Address
fn parse_mac_addr(dns_data: &[u8]) -> nom::IResult<&[u8], String> {
let mut mac_data: Vec<String> = Vec::new();
let mut data = dns_data;

while !data.is_empty() {
let (remaining_data, addr) = take(size_of::<u8>())(data)?;
data = remaining_data;

let (_, mac_addr) = be_u8(addr)?;
mac_data.push(format!("{:02X?}", mac_addr));
}
Ok((data, mac_data.join(":")))
Ok(map(
many0(map(be_u8, |val| format!("{:02X?}", val))),
|vals| vals.join(":"),
)(dns_data)?)
}

/// Get IP Address info from log data
Expand Down Expand Up @@ -687,7 +685,7 @@ mod tests {
let test_data =
"AAEAAAEAAwJoMgAEAAhoEJRAaBCVQAAGACAmBkcAAAAAAAAAAABoEJRAJgZHAAAAAAAAAAAAaBCVQA==";
let result = get_service_binding(&test_data);
assert_eq!(result, "rdata: 1 . alpn=h2, ipv4 hint:104.16.148.64,104.16.149.64, ipv6 hint:2606:4700::6810:9440,2606:4700::6810:9540,");
assert_eq!(result, "rdata: 1 . alpn=h2, ipv4 hint:104.16.148.64,104.16.149.64, ipv6 hint:2606:4700::6810:9440,2606:4700::6810:9540");
}

#[test]
Expand All @@ -697,7 +695,7 @@ mod tests {
let decoded_data_result = decode_standard(test_data).unwrap();

let (_, result) = parse_svcb(&decoded_data_result).unwrap();
assert_eq!(result, "rdata: 1 . alpn=h2, ipv4 hint:104.16.148.64,104.16.149.64, ipv6 hint:2606:4700::6810:9440,2606:4700::6810:9540,");
assert_eq!(result, "rdata: 1 . alpn=h2, ipv4 hint:104.16.148.64,104.16.149.64, ipv6 hint:2606:4700::6810:9440,2606:4700::6810:9540");
}

#[test]
Expand All @@ -716,7 +714,7 @@ mod tests {
];

let (_, result) = parse_svcb_ip(&test_data).unwrap();
assert_eq!(result, "ipv4 hint:104.16.148.64,104.16.149.64, ipv6 hint:2606:4700::6810:9440,2606:4700::6810:9540,");
assert_eq!(result, "ipv4 hint:104.16.148.64,104.16.149.64, ipv6 hint:2606:4700::6810:9440,2606:4700::6810:9540");
}

#[test]
Expand Down