fix: handle = syntax and some tokens

This commit is contained in:
2026-02-01 15:36:09 +01:00
parent ba8537063f
commit 6108b3f481
4 changed files with 422 additions and 246 deletions

View File

@@ -1,5 +1,7 @@
[package]
name = "lssh"
description = "List host names in ssh_config(5) files"
license = "MIT"
version = "0.1.0"
edition = "2024"

View File

@@ -11,7 +11,7 @@
//! [ssh(1)]: <https://manpages.debian.org/testing/manpages-de/ssh.1.de.html>
//! [ssh_config(5)]: <https://manpages.debian.org/bullseye/openssh-client/ssh_config.5.en.html>
mod words;
mod ssh;
use std::{
collections::HashSet,
@@ -25,9 +25,7 @@ use std::{
use clap::Parser;
use glob::glob;
use crate::words::{Keyword, Words, expand};
const SYSTEM_CONFIG: &str = "/etc/ssh/ssh_config";
use crate::ssh::{SSH_SYSTEM_CONFIG, SSH_USER_CONFIG, Words, expand_inlude_args, is_host_pattern};
/// List host names in ssh_config(5) files
#[derive(Debug, Parser)]
@@ -44,8 +42,8 @@ fn main() {
Some(path) if path == "none" => vec![],
Some(path) => vec![path.clone()],
None => match env::home_dir() {
Some(home) => vec![SYSTEM_CONFIG.into(), home.join(".ssh/config")],
None => vec![SYSTEM_CONFIG.into()],
Some(home) => vec![SSH_SYSTEM_CONFIG.into(), home.join(SSH_USER_CONFIG)],
None => vec![SSH_SYSTEM_CONFIG.into()],
},
};
@@ -61,7 +59,7 @@ fn main() {
};
}
let mut hosts = Vec::from_iter(hosts.into_iter());
let mut hosts = Vec::from_iter(hosts);
hosts.sort();
hosts
};
@@ -94,30 +92,31 @@ fn find_hosts(filename: &Path) -> io::Result<HashSet<String>> {
let line = buf[..n].trim();
let mut words: Words<'_> = line.into();
let Some(Ok(directive)) = words.next() else {
continue;
};
let Ok(keyword) = Keyword::try_from(directive.as_str()) else {
let Some(Ok(keyword)) = words.next() else {
continue;
};
match keyword {
Keyword::Include => find_hosts_in_include_directive(&mut hosts, words),
Keyword::Host => find_hosts_in_host_directive(&mut hosts, words),
k if k.eq_ignore_ascii_case("include") => {
find_hosts_in_include_directive(&mut hosts, words);
}
k if k.eq_ignore_ascii_case("host") => {
find_hosts_in_host_directive(&mut hosts, words);
}
_ => continue,
}
}
}
fn find_hosts_in_include_directive(hosts: &mut HashSet<String>, words: Words<'_>) {
for pattern in words {
let Ok(pattern) = pattern else {
for arg in words {
let Ok(arg) = arg else {
// TODO: print warning
continue;
};
// Expanding env vars before globbing is what ssh does as well.
let Ok(pattern) = expand(&pattern) else {
let Ok(pattern) = expand_inlude_args(arg) else {
// TODO: print warning
continue;
};
@@ -145,18 +144,17 @@ fn find_hosts_in_include_directive(hosts: &mut HashSet<String>, words: Words<'_>
}
fn find_hosts_in_host_directive(hosts: &mut HashSet<String>, words: Words<'_>) {
for host in words {
let Ok(host) = host else {
for word in words {
let Ok(word) = word else {
// TODO: print warning
continue;
};
if host.contains(['*', '?', '!', ',']) {
// Ignore patterns (see ssh_config(5) "PATTERNS").
if is_host_pattern(word) {
continue;
}
hosts.insert(host.into());
hosts.insert(word.to_string());
}
}
@@ -172,7 +170,7 @@ mod tests {
}
#[test]
fn test() {
fn find_hosts() {
let mut hosts = HashSet::new();
find_hosts_in_host_directive(&mut hosts, "foo.test".into());
assert!(hosts.contains("foo.test"));

399
src/ssh.rs Normal file
View File

@@ -0,0 +1,399 @@
use std::{collections::HashMap, env, path::PathBuf, str::CharIndices, sync::OnceLock};
pub const SSH_SYSTEM_CONFIG: &str = "/etc/ssh/ssh_config";
pub const SSH_USER_CONFIG: &str = ".ssh/config";
static ENV: OnceLock<Env> = OnceLock::new();
#[derive(Debug, PartialEq)]
pub struct InvalidQuotesError;
#[derive(Debug, PartialEq)]
pub enum ExpandError {
/// Missing closing delimiter `}`.
EnvMissingClosing { var: String },
/// The environment variable does not exist.
EnvNoValue { var: String },
/// The environment variable has not name (`${}`).
EnvZeroLen,
/// The token was invalid for the keyword.
TokenUnkownKey { token: char },
/// A token was expected, but was missing.
TokenInvalidFormat,
/// The token was valid, but is not implemented.
TokenNotImplemented { token: char },
}
/// Context that can expand words.
struct Env {
home_dir: PathBuf,
vars: HashMap<String, String>,
}
/// Iterator over words in a ssh_config(5) keyword-argument pair.
pub struct Words<'a> {
chars: CharIndices<'a>,
s: &'a str,
state: WordsExpect,
}
enum WordsExpect {
Keyword,
EqualsOrArgument,
Arguments,
}
pub fn expand_inlude_args(s: &str) -> Result<String, ExpandError> {
ENV.get_or_init(Env::from_env).expand_include_arg(s)
}
pub fn is_host_pattern(s: &str) -> bool {
s.contains(['*', '?', '!', ','])
}
impl<'a> From<&'a str> for Words<'a> {
fn from(s: &'a str) -> Self {
Self {
s,
chars: s.char_indices(),
state: WordsExpect::Keyword,
}
}
}
impl<'a> Iterator for Words<'a> {
type Item = Result<&'a str, InvalidQuotesError>;
fn next(&mut self) -> Option<Self::Item> {
use WordsExpect as Expect;
macro_rules! word {
($range:expr) => {
match self.state {
Expect::Keyword => {
self.state = Expect::EqualsOrArgument;
Some(Ok(&self.s[$range]))
}
Expect::EqualsOrArgument | Expect::Arguments => {
self.state = Expect::Arguments;
Some(Ok(&self.s[$range]))
}
}
};
($range:expr; $state:ident) => {
match self.state {
Expect::Keyword => {
self.state = Expect::$state;
Some(Ok(&self.s[$range]))
}
Expect::EqualsOrArgument | Expect::Arguments => {
self.state = Expect::$state;
Some(Ok(&self.s[$range]))
}
}
};
}
let (idx, ch) = loop {
let (idx, ch) = self.chars.next()?;
match (ch, &self.state) {
('=', Expect::EqualsOrArgument) => {
self.state = Expect::Arguments;
}
(ch, _) if ch.is_whitespace() => {}
_ => break (idx, ch),
}
};
match ch {
'\'' | '"' => {
let delim = ch;
let start_idx = idx + 1;
loop {
match self.chars.next() {
Some((idx, ch)) if ch == delim => {
return word!(start_idx..idx);
}
Some(_) => {}
// End of words, but no closing delimiter for current word.
None => return Some(Err(InvalidQuotesError)),
}
}
}
_ => {
let start_idx = idx;
loop {
match (&self.state, self.chars.next()) {
(Expect::Keyword, Some((idx, '='))) => {
return word!(start_idx..idx; Arguments);
}
(_, Some((idx, ch))) if ch.is_whitespace() => {
return word!(start_idx..idx);
}
(_, Some(_)) => {}
(_, None) => return word!(start_idx..),
}
}
}
};
}
}
impl Env {
fn from_env() -> Self {
let mut vars = HashMap::new();
for (var, val) in env::vars_os() {
let Some(var) = var.to_str() else {
continue;
};
let Some(val) = val.to_str() else {
continue;
};
vars.insert(var.to_string(), val.to_string());
}
Self {
home_dir: env::home_dir().unwrap_or_else(|| PathBuf::from("~")),
vars,
}
}
fn home_dir_str(&self) -> &str {
self.home_dir.to_str().unwrap_or("~")
}
fn expand_include_arg(&self, arg: &str) -> Result<String, ExpandError> {
enum S {
Literal,
EnvVar,
MaybeEnvVar,
ExpectToken,
}
let mut expanded = String::new();
let mut state = S::Literal;
let mut var_start: Option<usize> = None;
for (idx, ch) in arg.char_indices() {
match (&state, ch) {
(S::Literal | S::MaybeEnvVar, '~') => {
expanded.push_str(self.home_dir_str());
state = S::Literal;
}
(S::Literal | S::MaybeEnvVar, '%') => state = S::ExpectToken,
(S::Literal, '$') => state = S::MaybeEnvVar,
(S::Literal, ch) => expanded.push(ch),
(S::MaybeEnvVar, '$') => expanded.push('$'),
(S::MaybeEnvVar, '{') => {
state = S::EnvVar;
var_start = None;
}
(S::MaybeEnvVar, ch) => {
state = S::Literal;
expanded.push('$');
expanded.push(ch);
}
(S::EnvVar, '}') => {
let Some(start) = var_start else {
return Err(ExpandError::EnvZeroLen);
};
let var = &arg[start..idx];
let Some(val) = self.vars.get(var) else {
return Err(ExpandError::EnvNoValue {
var: var.to_string(),
});
};
if val == "~" {
expanded.push_str(self.home_dir_str());
} else {
expanded.push_str(val);
}
state = S::Literal;
}
(S::EnvVar, _) => {
if var_start.is_none() {
var_start = Some(idx)
}
}
(S::ExpectToken, ch) => {
state = S::Literal;
macro_rules! unimplemented_token {
($t:expr) => {{
return Err(ExpandError::TokenNotImplemented { token: $t });
}};
}
match ch {
// A literal %.
'%' => expanded.push('%'),
// Hash of %l%h%p%r%j.
'C' => unimplemented_token!(ch),
// Local user's home directory.
'd' => expanded.push_str(self.home_dir_str()),
// The fingerprint of the server's host key.
// ('f', _) => todo!(),
// The known_hosts hostname or address that is being searched for.
// ('H', _) => todo!(),
// The remote hostname.
'h' => unimplemented_token!(ch),
// A string describing the reason for a KnownHostsCommand execution: either
// ADDRESS when looking up a host by address (only when CheckHostIP is
// enabled), HOSTNAME when searching by hostname, or ORDER when preparing
// the host key algorithm preference list to use for the destination host.
// ('I', _) => todo!(),
// The local user ID.
'i' => unimplemented_token!(ch),
// The contents of the ProxyJump option, or the empty string if this option
// is unset.
'j' => unimplemented_token!(ch),
// The base64 encoded host key.
// ('K', _) => todo!(),
// The host key alias if specified, otherwise the original remote hostname
// given on the command line.
'k' => unimplemented_token!(ch),
// The local hostname.
'L' => unimplemented_token!(ch),
// The local hostname, including the domain name.
'l' => unimplemented_token!(ch),
// The original remote hostname, as given on the command line.
'n' => unimplemented_token!(ch),
// The remote port.
'p' => unimplemented_token!(ch),
// The remote username.
'r' => unimplemented_token!(ch),
// The local tun(4) or tap(4) network interface assigned if tunnel
// forwarding was requested, or "NONE" otherwise.
// ('T', _) => todo!(),
// The type of the server host key, e.g. ssh-ed25519.
// ('t', _) => todo!(),
// The local username.
'u' => unimplemented_token!(ch),
// Unknown key %*.
_ => return Err(ExpandError::TokenUnkownKey { token: ch }),
}
}
}
}
match state {
S::Literal => {}
S::MaybeEnvVar => expanded.push('$'),
S::EnvVar => {
let start = var_start.expect("var_start must be set");
return Err(ExpandError::EnvMissingClosing {
var: arg[start..].to_string(),
});
}
S::ExpectToken => {
return Err(ExpandError::TokenInvalidFormat);
}
}
Ok(expanded)
}
}
impl std::error::Error for InvalidQuotesError {}
impl std::fmt::Display for InvalidQuotesError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "invalid quotes")
}
}
impl std::error::Error for ExpandError {}
impl std::fmt::Display for ExpandError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
use ExpandError::*;
match self {
EnvMissingClosing { var } => {
write!(f, "environment variable '{var}' missing closing '}}'")
}
EnvNoValue { var } => write!(f, "env var ${{{var}}} has no value"),
EnvZeroLen => write!(f, "zero-length environment variable"),
TokenUnkownKey { token } => write!(f, "unknown key %{token}"),
TokenInvalidFormat => write!(f, "invalid format"),
TokenNotImplemented { token } => {
write!(f, "valid key %{token} is not implemented")
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn parse_words() {
macro_rules! assert_words {
($words:expr, $parsed:expr) => {
assert_eq!(
Words::from($words).collect::<Vec<Result<_, _>>>()[..],
$parsed,
)
};
}
assert_words!("foo bar baz", [Ok("foo"), Ok("bar"), Ok("baz")]);
assert_words!("foo \"bar \" ' baz'", [Ok("foo"), Ok("bar "), Ok(" baz")]);
assert_words!("foo 'bar\"", [Ok("foo"), Err(InvalidQuotesError)]);
assert_words!("foo==bar", [Ok("foo"), Ok("=bar")]);
assert_words!("foo '==bar'", [Ok("foo"), Ok("==bar")]);
assert_words!("foo='=bar'", [Ok("foo"), Ok("=bar")]);
assert_words!("'foo''==bar'", [Ok("foo"), Ok("==bar")]);
}
#[test]
fn expand_include_args() {
let env = Env {
home_dir: PathBuf::from("/home/jhill"),
vars: HashMap::from([
("FOO".to_string(), "foo".to_string()),
("BAR".to_string(), "bar".to_string()),
("BAZ".to_string(), "baz".to_string()),
("QUX".to_string(), "~".to_string()),
]),
};
macro_rules! assert_expand {
($e:expr, $expanded:expr) => {
assert_eq!(env.expand_include_arg($e).as_deref(), $expanded)
};
}
assert_expand!("~", Ok("/home/jhill"));
assert_expand!("FOO ${BAR} ${BAZ}", Ok("FOO bar baz"));
assert_expand!("~/${FOO}", Ok("/home/jhill/foo"));
assert_expand!("${QUX}/${FOO}", Ok("/home/jhill/foo"));
// Environment expansion errors.
// TODO: Is this emulating the ssh behaviour?
assert_expand!(
"foo ${QUUX} baz",
Err(&ExpandError::EnvNoValue {
var: "QUUX".to_string()
})
);
assert_expand!(
"foo ${BAR baz",
Err(&ExpandError::EnvMissingClosing {
var: "BAR baz".to_string()
})
);
assert_expand!("foo ${} baz", Err(&ExpandError::EnvZeroLen));
// Token expansion errors.
assert_expand!("%", Err(&ExpandError::TokenInvalidFormat));
assert_expand!("%Z", Err(&ExpandError::TokenUnkownKey { token: 'Z' }));
assert_expand!("%C", Err(&ExpandError::TokenNotImplemented { token: 'C' }));
}
}

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@@ -1,223 +0,0 @@
use std::{collections::HashMap, env, path::PathBuf, str::Chars, sync::OnceLock};
static EXPANDER: OnceLock<Env> = OnceLock::new();
/// Missing `'\''`, `'"'` or `'}'` delimiter.
#[derive(Debug)]
pub struct MissingDelimiter;
/// Iterator over words in str.
pub struct Words<'a> {
chars: Chars<'a>,
}
pub enum Keyword {
Host,
Include,
}
/// Context that can expand words.
struct Env {
dir: PathBuf,
vars: HashMap<String, String>,
}
/// Expand env vars in the given word.
pub fn expand(word: &str) -> Result<String, MissingDelimiter> {
EXPANDER.get_or_init(|| Env::from_env()).expand(word)
}
impl Iterator for Words<'_> {
type Item = Result<String, MissingDelimiter>;
fn next(&mut self) -> Option<Self::Item> {
let ch = loop {
let ch = self.chars.next()?;
if !ch.is_whitespace() {
break ch;
}
};
let mut word = String::new();
match ch {
'\'' | '"' => {
let delim = ch;
loop {
match self.chars.next() {
Some(ch) if ch == delim => {
return Some(Ok(word));
}
Some(ch) => word.push(ch),
None => return Some(Err(MissingDelimiter)),
}
}
}
ch => {
word.push(ch);
loop {
match self.chars.next() {
Some(ch) if ch.is_whitespace() => return Some(Ok(word)),
Some(ch) => word.push(ch),
None => return Some(Ok(word)),
}
}
}
};
}
}
impl TryFrom<&str> for Keyword {
type Error = ();
fn try_from(value: &str) -> Result<Keyword, Self::Error> {
let keyword = match value.to_lowercase().as_str() {
"host" => Keyword::Host,
"include" => Keyword::Include,
_ => return Err(()),
};
Ok(keyword)
}
}
impl<'a> From<&'a str> for Words<'a> {
fn from(value: &'a str) -> Self {
Words {
chars: value.chars(),
}
}
}
impl Env {
fn from_env() -> Self {
let mut vars = HashMap::new();
for (var, val) in env::vars_os() {
let Some(var) = var.to_str() else {
continue;
};
let Some(val) = val.to_str() else {
continue;
};
vars.insert(var.to_string(), val.to_string());
}
Self {
dir: env::home_dir().unwrap_or_else(|| PathBuf::from("~")),
vars,
}
}
fn dir_str(&self) -> &str {
self.dir.to_str().unwrap_or("~")
}
fn expand(&self, word: &str) -> Result<String, MissingDelimiter> {
let mut chars = word.chars();
let mut expanded = String::new();
'outer: while let Some(ch) = chars.next() {
match ch {
'$' => {
let Some(ch) = chars.next() else {
expanded.push('$');
break;
};
if ch != '{' {
expanded.push('$');
expanded.push(ch);
break;
}
let mut var = String::new();
while let Some(ch) = chars.next() {
match ch {
'}' => match self.vars.get(&var) {
Some(val) if val == "~" => {
// ssh -vG indeed shows this to be true
expanded.push_str(self.dir_str());
continue 'outer;
}
Some(val) => {
expanded.push_str(val);
continue 'outer;
}
None => {
// TODO: I *think* the word must be ignored if the var is not
// set?
expanded.push('$');
expanded.push('{');
expanded.push_str(&var);
expanded.push('}');
continue 'outer;
}
},
ch => var.push(ch),
}
}
return Err(MissingDelimiter);
}
'~' => expanded.push_str(self.dir_str()),
ch => expanded.push(ch),
}
}
Ok(expanded)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn words() {
let mut words = Words::from("foo bar baz");
assert_eq!(words.next().unwrap().unwrap(), "foo");
assert_eq!(words.next().unwrap().unwrap(), "bar");
assert_eq!(words.next().unwrap().unwrap(), "baz");
assert!(words.next().is_none());
let mut words = Words::from("foo \"bar baz\"");
assert_eq!(words.next().unwrap().unwrap(), "foo");
assert_eq!(words.next().unwrap().unwrap(), "bar baz");
assert!(words.next().is_none());
let mut words = Words::from("foo 'bar baz'");
assert_eq!(words.next().unwrap().unwrap(), "foo");
assert_eq!(words.next().unwrap().unwrap(), "bar baz");
assert!(words.next().is_none());
let mut words = Words::from("foo 'bar baz\"");
assert_eq!(words.next().unwrap().unwrap(), "foo");
assert!(words.next().unwrap().is_err());
assert!(words.next().is_none());
}
#[test]
fn expand() {
let expander = Env {
dir: PathBuf::from("/home/jhill"),
vars: HashMap::from([
("FOO".to_string(), "foo".to_string()),
("BAR".to_string(), "bar".to_string()),
("BAZ".to_string(), "baz".to_string()),
("WEIRD".to_string(), "~".to_string()),
]),
};
assert_eq!(expander.expand("~").unwrap(), "/home/jhill");
assert_eq!(expander.expand("FOO ${BAR} ${BAZ}").unwrap(), "FOO bar baz");
assert_eq!(expander.expand("~/${FOO}").unwrap(), "/home/jhill/foo");
assert_eq!(
expander.expand("${WEIRD}/${FOO}").unwrap(),
"/home/jhill/foo"
);
// TODO: Is this emulating the ssh behaviour?
assert_eq!(expander.expand("foo ${QUX} baz").unwrap(), "foo ${QUX} baz");
assert!(expander.expand("foo ${BAR baz").is_err());
}
}