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use std::{
ffi::OsString,
os::unix::{ffi::OsStringExt, fs::MetadataExt},
path::{Component, Path, PathBuf},
};
use mlua::{AnyUserData, Lua, UserData, Value};
use tokio::{fs, io};
#[derive(Debug, thiserror::Error)]
pub enum InitLuaError {
#[error("failed to create variable: {0}")]
CreateTable(mlua::Error),
#[error("failed to create helper function: {0}")]
Function(mlua::Error),
#[error("failed to set variable {1}: {0}")]
SetVar(mlua::Error, String),
#[error("failed to load variable {1}: {0}")]
LoadVar(mlua::Error, String),
#[error("failed to load config: {0}")]
LoadConfig(std::io::Error),
#[error("failed to eval config: {0}")]
EvalConfig(mlua::Error),
}
#[derive(Debug, thiserror::Error)]
enum JoinPathError {
#[error("unsafe path")]
Unsafe,
#[error("io error: {0}")]
Io(#[from] std::io::Error),
}
#[derive(Debug)]
pub struct File(Option<fs::File>);
#[derive(Debug)]
struct Metadata(std::fs::Metadata);
impl File {
pub fn take(&mut self) -> Option<fs::File> {
self.0.take()
}
}
impl UserData for File {}
impl UserData for Metadata {
fn add_fields<F: mlua::UserDataFields<Self>>(fields: &mut F) {
fields.add_field_method_get("len", |_, this| Ok(this.0.len()));
fields.add_field_method_get("mtime", |_, this| Ok(this.0.mtime_nsec()))
}
}
fn join_path<A: AsRef<Path>, B: AsRef<Path>>(root: A, rest: B) -> Result<PathBuf, JoinPathError> {
let mut pathbuf = root.as_ref().to_path_buf();
for component in rest.as_ref().components() {
match component {
Component::Normal(path) => {
pathbuf.push(path);
}
Component::ParentDir => {
pathbuf.pop();
if !pathbuf.starts_with(root.as_ref()) {
return Err(JoinPathError::Unsafe);
}
}
_ => continue,
}
}
let canon = match pathbuf.canonicalize() {
Ok(canon) => canon,
Err(e) if matches!(e.kind(), std::io::ErrorKind::NotFound) => pathbuf,
Err(e) => return Err(JoinPathError::Io(e)),
};
if !canon.starts_with(root.as_ref()) {
return Err(JoinPathError::Unsafe);
}
Ok(canon)
}
pub(super) fn init(lua: Lua) -> Result<(), InitLuaError> {
let http = lua.create_table().map_err(InitLuaError::CreateTable)?;
lua.globals()
.set("http", http.clone())
.map_err(|e| InitLuaError::SetVar(e, "http".to_string()))?;
http.set(
"join_paths",
lua.create_function(|_, (root, rest): (mlua::String, mlua::String)| {
let a = PathBuf::from(OsString::from_vec(root.as_bytes().to_vec()));
let b = PathBuf::from(OsString::from_vec(rest.as_bytes().to_vec()));
join_path(&a, &b).map_err(|e| mlua::Error::runtime(format!("failed to join path: {e}")))
})
.map_err(InitLuaError::Function)?,
)
.map_err(|e| InitLuaError::SetVar(e, "http.join_paths".to_string()))?;
let io = lua.create_table().map_err(InitLuaError::CreateTable)?;
http.set("io", io.clone())
.map_err(|e| InitLuaError::SetVar(e, "http.io".to_string()))?;
io.set(
"fopen",
lua.create_async_function(|lua, path: mlua::String| async move {
let pathbuf = PathBuf::from(OsString::from_vec(path.as_bytes().to_vec()));
match fs::File::open(&pathbuf).await {
Ok(f) => {
let data = lua.create_any_userdata(File(Some(f)))?;
Ok(Value::UserData(data))
}
Err(e) if matches!(e.kind(), io::ErrorKind::NotFound) => Ok(Value::Nil),
Err(e) => Err(mlua::Error::runtime(format!("failed to open file: {e}"))),
}
})
.map_err(InitLuaError::Function)?,
)
.map_err(|e| InitLuaError::SetVar(e, "http.io.fopen".to_string()))?;
io.set(
"metadata",
lua.create_async_function(|_, file: AnyUserData| async move {
let metadata = match file.borrow::<File>() {
Ok(f) => f.0.as_ref().unwrap().metadata().await.map_err(|e| {
mlua::Error::runtime(format!("failed to read file metadata: {e}"))
})?,
Err(_) => {
return Err(mlua::Error::runtime(
"failed to read file metadata, expected file type",
));
}
};
Ok(Metadata(metadata))
})
.map_err(InitLuaError::Function)?,
)
.map_err(|e| InitLuaError::SetVar(e, "http.io.stat".to_string()))?;
let chunk = lua.load(std::fs::read_to_string("config.lua").map_err(InitLuaError::LoadConfig)?);
chunk.eval::<()>().map_err(InitLuaError::EvalConfig)?;
Ok(())
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_path_traversal() {
let root = "/var/www";
let get = "/../../bin/sh";
let joined = join_path(root, get);
assert!(matches!(joined, Err(JoinPathError::Unsafe)));
}
}
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