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parse dig's output

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This commit is contained in:
Jorge Aparicio 2024-02-06 16:47:18 +01:00
parent fc7cf970a5
commit 7ad5bacbdc
6 changed files with 466 additions and 56 deletions
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51
src/authoritative_name_server.rs
View File

@ -85,7 +85,6 @@ impl StoppedAuthoritativeNameServer {
/// - one SOA record, with the primary name server set to the name server domain
/// - one NS record, with the name server domain set as the only available name server for
/// `zone`
/// - one A record, that maps the name server domain to its IPv4 address
/// - one NS + A record pair, for each referral in the `referrals` list
/// - the A records in the `a_records` list
pub fn start<'a>(
@ -119,10 +118,6 @@ impl StoppedAuthoritativeNameServer {
domain: zone.clone(),
ns: nameserver.clone(),
});
zone_file.record(record::A {
domain: nameserver,
ipv4_addr: container.ipv4_addr(),
});
for referral in referrals {
zone_file.referral(referral)
@ -153,45 +148,35 @@ fn nsd_conf(domain: &Domain) -> String {
#[cfg(test)]
mod tests {
use crate::{
client::{RecordType, Recurse},
Client,
};
use super::*;
#[test]
fn tld_ns() -> Result<()> {
let tld_ns = AuthoritativeNameServer::start(Domain("com.")?, &[], &[])?;
fn simplest() -> Result<()> {
let com_domain = Domain("com.")?;
let tld_ns = AuthoritativeNameServer::start(com_domain.clone(), &[], &[])?;
let ip_addr = tld_ns.ipv4_addr();
let client = Container::run()?;
let output = client.output(&["dig", &format!("@{ip_addr}"), "SOA", "com."])?;
let client = Client::new()?;
let output = client.dig(Recurse::No, ip_addr, RecordType::SOA, &com_domain)?;
assert!(output.status.success());
eprintln!("{}", output.stdout);
assert!(output.stdout.contains("status: NOERROR"));
assert!(output.status.is_noerror());
Ok(())
}
#[test]
fn root_ns() -> Result<()> {
let root_ns = AuthoritativeNameServer::start(Domain::ROOT, &[], &[])?;
let ip_addr = root_ns.ipv4_addr();
let client = Container::run()?;
let output = client.output(&["dig", &format!("@{ip_addr}"), "SOA", "."])?;
assert!(output.status.success());
eprintln!("{}", output.stdout);
assert!(output.stdout.contains("status: NOERROR"));
Ok(())
}
#[test]
fn root_ns_with_referral() -> Result<()> {
fn with_referral() -> Result<()> {
let expected_ip_addr = Ipv4Addr::new(172, 17, 200, 1);
let com_domain = Domain("com.")?;
let root_ns = AuthoritativeNameServer::start(
Domain::ROOT,
&[Referral {
domain: Domain("com.")?,
domain: com_domain.clone(),
ipv4_addr: expected_ip_addr,
ns: Domain("primary.tld-server.com.")?,
}],
@ -199,12 +184,10 @@ mod tests {
)?;
let ip_addr = root_ns.ipv4_addr();
let client = Container::run()?;
let output = client.output(&["dig", &format!("@{ip_addr}"), "NS", "com."])?;
let client = Client::new()?;
let output = client.dig(Recurse::No, ip_addr, RecordType::NS, &com_domain)?;
assert!(output.status.success());
eprintln!("{}", output.stdout);
assert!(output.stdout.contains("status: NOERROR"));
assert!(output.status.is_noerror());
Ok(())
}

408
src/client.rs Normal file
View File

@ -0,0 +1,408 @@
use core::array;
use core::result::Result as CoreResult;
use core::str::FromStr;
use std::net::Ipv4Addr;
use crate::container::Container;
use crate::{Domain, Error, Result};
pub struct Client {
inner: Container,
}
impl Client {
pub fn new() -> Result<Self> {
Ok(Self {
inner: Container::run()?,
})
}
pub fn dig(
&self,
recurse: Recurse,
server: Ipv4Addr,
record_type: RecordType,
domain: &Domain<'_>,
) -> Result<DigOutput> {
let output = self.inner.stdout(&[
"dig",
recurse.as_str(),
&format!("@{server}"),
record_type.as_str(),
domain.as_str(),
])?;
output.parse()
}
}
#[allow(clippy::upper_case_acronyms)]
pub enum RecordType {
A,
NS,
SOA,
}
impl RecordType {
fn as_str(&self) -> &'static str {
match self {
RecordType::A => "A",
RecordType::SOA => "SOA",
RecordType::NS => "NS",
}
}
}
#[derive(Clone, Copy)]
pub enum Recurse {
Yes,
No,
}
impl Recurse {
fn as_str(&self) -> &'static str {
match self {
Recurse::Yes => "+recurse",
Recurse::No => "+norecurse",
}
}
}
pub struct DigOutput {
pub flags: DigFlags,
pub status: DigStatus,
pub answer: Vec<Record>,
// TODO(if needed) other sections
}
impl FromStr for DigOutput {
type Err = Error;
fn from_str(input: &str) -> Result<Self> {
const FLAGS_PREFIX: &str = ";; flags: ";
const STATUS_PREFIX: &str = ";; ->>HEADER<<- opcode: QUERY, status: ";
const ANSWER_HEADER: &str = ";; ANSWER SECTION:";
fn not_found(prefix: &str) -> String {
format!("`{prefix}` line was not found")
}
fn more_than_once(prefix: &str) -> String {
format!("`{prefix}` line was found more than once")
}
fn missing(prefix: &str, delimiter: &str) -> String {
format!("`{prefix}` line is missing a {delimiter}")
}
let mut flags = None;
let mut status = None;
let mut answer = None;
let mut lines = input.lines();
while let Some(line) = lines.next() {
if let Some(unprefixed) = line.strip_prefix(FLAGS_PREFIX) {
let (flags_text, _rest) = unprefixed
.split_once(';')
.ok_or_else(|| missing(FLAGS_PREFIX, "semicolon (;)"))?;
if flags.is_some() {
return Err(more_than_once(FLAGS_PREFIX).into());
}
flags = Some(flags_text.parse()?);
} else if let Some(unprefixed) = line.strip_prefix(STATUS_PREFIX) {
let (status_text, _rest) = unprefixed
.split_once(',')
.ok_or_else(|| missing(STATUS_PREFIX, "comma (,)"))?;
if status.is_some() {
return Err(more_than_once(STATUS_PREFIX).into());
}
status = Some(status_text.parse()?);
} else if line.starts_with(ANSWER_HEADER) {
if answer.is_some() {
return Err(more_than_once(ANSWER_HEADER).into());
}
let mut records = vec![];
for line in lines.by_ref() {
if line.is_empty() {
break;
}
records.push(line.parse()?);
}
answer = Some(records);
}
}
Ok(Self {
flags: flags.ok_or_else(|| not_found(FLAGS_PREFIX))?,
status: status.ok_or_else(|| not_found(STATUS_PREFIX))?,
answer: answer.unwrap_or_default(),
})
}
}
#[derive(Debug, Default, PartialEq)]
pub struct DigFlags {
pub qr: bool,
pub recursion_desired: bool,
pub recursion_available: bool,
pub authoritative_answer: bool,
}
impl FromStr for DigFlags {
type Err = Error;
fn from_str(input: &str) -> std::prelude::v1::Result<Self, Self::Err> {
let mut qr = false;
let mut recursion_desired = false;
let mut recursion_available = false;
let mut authoritative_answer = false;
for flag in input.split_whitespace() {
match flag {
"qr" => qr = true,
"rd" => recursion_desired = true,
"ra" => recursion_available = true,
"aa" => authoritative_answer = true,
_ => return Err(format!("unknown flag: {flag}").into()),
}
}
Ok(Self {
qr,
recursion_desired,
recursion_available,
authoritative_answer,
})
}
}
#[allow(clippy::upper_case_acronyms)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum DigStatus {
NOERROR,
NXDOMAIN,
REFUSED,
}
impl DigStatus {
#[must_use]
pub fn is_noerror(&self) -> bool {
matches!(self, Self::NOERROR)
}
}
impl FromStr for DigStatus {
type Err = Error;
fn from_str(input: &str) -> Result<Self> {
let status = match input {
"NXDOMAIN" => Self::NXDOMAIN,
"NOERROR" => Self::NOERROR,
"REFUSED" => Self::REFUSED,
_ => return Err(format!("unknown status: {input}").into()),
};
Ok(status)
}
}
#[derive(Debug)]
#[allow(clippy::upper_case_acronyms)]
pub enum Record {
A(A),
SOA(SOA),
}
impl Record {
pub fn try_into_a(self) -> CoreResult<A, Self> {
if let Self::A(v) = self {
Ok(v)
} else {
Err(self)
}
}
}
impl FromStr for Record {
type Err = Error;
fn from_str(input: &str) -> Result<Self> {
let record_type = input
.split_whitespace()
.nth(3)
.ok_or("record is missing the type column")?;
let record = match record_type {
"A" => Record::A(input.parse()?),
"NS" => todo!(),
"SOA" => Record::SOA(input.parse()?),
_ => return Err(format!("unknown record type: {record_type}").into()),
};
Ok(record)
}
}
#[derive(Debug)]
pub struct A {
pub domain: Domain<'static>,
pub ttl: u32,
pub ipv4_addr: Ipv4Addr,
}
impl FromStr for A {
type Err = Error;
fn from_str(input: &str) -> Result<Self> {
let mut columns = input.split_whitespace();
let [Some(domain), Some(ttl), Some(class), Some(record_type), Some(ipv4_addr), None] =
array::from_fn(|_| columns.next())
else {
return Err("expected 5 columns".into());
};
if record_type != "A" {
return Err(format!("tried to parse `{record_type}` record as an A record").into());
}
if class != "IN" {
return Err(format!("unknown class: {class}").into());
}
Ok(Self {
domain: domain.parse()?,
ttl: ttl.parse()?,
ipv4_addr: ipv4_addr.parse()?,
})
}
}
#[allow(clippy::upper_case_acronyms)]
#[derive(Debug)]
pub struct SOA {
pub domain: Domain<'static>,
pub ttl: u32,
pub nameserver: Domain<'static>,
pub admin: Domain<'static>,
pub serial: u32,
pub refresh: u32,
pub retry: u32,
pub expire: u32,
pub minimum: u32,
}
impl FromStr for SOA {
type Err = Error;
fn from_str(input: &str) -> Result<Self> {
let mut columns = input.split_whitespace();
let [Some(domain), Some(ttl), Some(class), Some(record_type), Some(nameserver), Some(admin), Some(serial), Some(refresh), Some(retry), Some(expire), Some(minimum), None] =
array::from_fn(|_| columns.next())
else {
return Err("expected 11 columns".into());
};
if record_type != "SOA" {
return Err(format!("tried to parse `{record_type}` record as a SOA record").into());
}
if class != "IN" {
return Err(format!("unknown class: {class}").into());
}
Ok(Self {
domain: domain.parse()?,
ttl: ttl.parse()?,
nameserver: nameserver.parse()?,
admin: admin.parse()?,
serial: serial.parse()?,
refresh: refresh.parse()?,
retry: retry.parse()?,
expire: expire.parse()?,
minimum: minimum.parse()?,
})
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn nxdomain() -> Result<()> {
// $ dig nonexistent.domain.
let input = "
; <<>> DiG 9.18.18-0ubuntu0.22.04.1-Ubuntu <<>> nonexistent.domain.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 45583
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;nonexistent.domain. IN A
;; Query time: 3 msec
;; SERVER: 192.168.1.1#53(192.168.1.1) (UDP)
;; WHEN: Tue Feb 06 15:00:12 UTC 2024
;; MSG SIZE rcvd: 47
";
let output: DigOutput = input.parse()?;
assert_eq!(DigStatus::NXDOMAIN, output.status);
assert_eq!(
DigFlags {
qr: true,
recursion_desired: true,
recursion_available: true,
..DigFlags::default()
},
output.flags
);
assert!(output.answer.is_empty());
Ok(())
}
#[test]
fn can_parse_a_record() -> Result<()> {
let input = "a.root-servers.net. 3600000 IN A 198.41.0.4";
let a: A = input.parse()?;
assert_eq!("a.root-servers.net.", a.domain.as_str());
assert_eq!(3600000, a.ttl);
assert_eq!(Ipv4Addr::new(198, 41, 0, 4), a.ipv4_addr);
Ok(())
}
#[test]
fn can_parse_soa_record() -> Result<()> {
let input = ". 15633 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2024020501 1800 900 604800 86400";
let soa: SOA = input.parse()?;
assert_eq!(".", soa.domain.as_str());
assert_eq!(15633, soa.ttl);
assert_eq!("a.root-servers.net.", soa.nameserver.as_str());
assert_eq!("nstld.verisign-grs.com.", soa.admin.as_str());
assert_eq!(2024020501, soa.serial);
assert_eq!(1800, soa.refresh);
assert_eq!(900, soa.retry);
assert_eq!(604800, soa.expire);
assert_eq!(86400, soa.minimum);
Ok(())
}
}

12
src/container.rs
View File

@ -95,6 +95,18 @@ impl Container {
command.output()?.try_into()
}
/// Similar to `Self::output` but checks `command_and_args` ran successfully and only
/// returns the stdout
pub fn stdout(&self, command_and_args: &[&str]) -> Result<String> {
let output = self.output(command_and_args)?;
if output.status.success() {
Ok(output.stdout)
} else {
Err(format!("[{}] `{command_and_args:?}` failed", self.name).into())
}
}
/// Similar to `std::process::Command::status` but runs `command_and_args` in the container
pub fn status(&self, command_and_args: &[&str]) -> Result<ExitStatus> {
let mut command = Command::new("docker");

19
src/domain.rs
View File

@ -1,9 +1,10 @@
use core::fmt;
use core::str::FromStr;
use std::borrow::Cow;
use crate::Result;
use crate::{Error, Result};
#[derive(Clone)]
#[derive(Clone, PartialEq)]
pub struct Domain<'a> {
inner: Cow<'a, str>,
}
@ -48,6 +49,20 @@ impl<'a> Domain<'a> {
}
}
impl FromStr for Domain<'static> {
type Err = Error;
fn from_str(input: &str) -> Result<Self> {
Ok(Domain(input)?.into_owned())
}
}
impl fmt::Debug for Domain<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(self, f)
}
}
impl fmt::Display for Domain<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(&self.inner)

2
src/lib.rs
View File

@ -1,6 +1,7 @@
use std::sync::atomic::{self, AtomicUsize};
pub use crate::authoritative_name_server::AuthoritativeNameServer;
pub use crate::client::Client;
pub use crate::domain::Domain;
pub use crate::recursive_resolver::RecursiveResolver;
@ -10,6 +11,7 @@ pub type Result<T> = core::result::Result<T, Error>;
const CHMOD_RW_EVERYONE: &str = "666";
mod authoritative_name_server;
mod client;
pub mod container;
mod domain;
pub mod record;

30
src/recursive_resolver.rs
View File

@ -41,8 +41,9 @@ impl Drop for RecursiveResolver {
#[cfg(test)]
mod tests {
use crate::{
client::{RecordType, Recurse},
record::{self, Referral},
AuthoritativeNameServer, Domain,
AuthoritativeNameServer, Client, Domain,
};
use super::*;
@ -51,6 +52,7 @@ mod tests {
fn can_resolve() -> Result<()> {
let expected_ipv4_addr = Ipv4Addr::new(1, 2, 3, 4);
let needle = Domain("example.nameservers.com.")?;
let root_ns = AuthoritativeNameServer::reserve()?;
let com_ns = AuthoritativeNameServer::reserve()?;
@ -105,28 +107,16 @@ mod tests {
let resolver = RecursiveResolver::start(roots)?;
let resolver_ip_addr = resolver.ipv4_addr();
let container = Container::run()?;
let output = container.output(&[
"dig",
&format!("@{}", resolver_ip_addr),
&needle.to_string(),
])?;
let client = Client::new()?;
let output = client.dig(Recurse::Yes, resolver_ip_addr, RecordType::A, &needle)?;
eprintln!("{}", output.stdout);
assert!(output.status.is_noerror());
assert!(output.status.success());
assert!(output.stdout.contains("status: NOERROR"));
let [answer] = output.answer.try_into().unwrap();
let a = answer.try_into_a().unwrap();
let mut found = false;
let needle = needle.to_string();
for line in output.stdout.lines() {
if line.starts_with(&needle) {
found = true;
assert!(line.ends_with(&expected_ipv4_addr.to_string()));
}
}
assert!(found);
assert_eq!(needle, a.domain);
assert_eq!(expected_ipv4_addr, a.ipv4_addr);
Ok(())
}