Added config validation

Author: NiklasVousten

README.md

@@ -136,6 +136,13 @@ tls_dns_name = "1dot1dot1dot1.cloudflare-dns.com"
 trust_nx_responses = false
 ```
 
+## Validation
+The config can be validated by running the following command.
+
+`cargo run -- --validate`
+
+This only validates the config, block- and allowlists, and does not start the DNS server. If the validation fails, the program exits with the error code `1`.
+
 ## DNSSEC Issues
 Due to an upstream issue of [hickory-dns](https://github.com/hickory-dns/hickory-dns/issues/2429), non DNSSEC sites will not be resolved if `validate = true`.
 Only DNSSEC capable sites will be resolved with this setting.

src/blocklist.rs

@@ -88,7 +88,7 @@ impl BlockList {
 
 		// block list
 		for url in adlist {
-			let (raw_list, mut list_errors) = get_file(url, restore_from_cache).await;
+			let (raw_list, mut list_errors) = get_file(url, restore_from_cache, true).await;
 			match raw_list {
 				None => {
 					error!("skipp list {url}");
@@ -141,7 +141,7 @@ impl BlockList {
 		// allow list
 		for url in allow_list {
 			info!("load allow list");
-			let (raw_list, mut list_errors) = get_file(url, restore_from_cache).await;
+			let (raw_list, mut list_errors) = get_file(url, restore_from_cache, true).await;
 			match raw_list {
 				None => error!("skipp list {url}"),
 				Some(raw_list) => {

src/main.rs

@@ -23,16 +23,10 @@ use reqwest::Client;
 use rustls::{Certificate, PrivateKey};
 use serde::Deserialize;
 use std::{
-	env::var,
-	fs::{self, File},
-	io::BufReader,
-	iter,
-	path::{Path, PathBuf},
-	sync::{
+	env::var, fs::{self, File}, io::BufReader, iter, path::{Path, PathBuf}, sync::{
 		atomic::{AtomicU64, Ordering},
 		Arc
-	},
-	time::Duration
+	}, time::Duration
 };
 use time::OffsetDateTime;
 use tokio::{
@@ -244,10 +238,12 @@ fn load_cert_and_key(
 	Ok((certificates, key))
 }
 
-/// load a text file from url and cache it.
-/// If restore_from_cache is true only the cache is used.
-/// Return None if an Err has occure.
-async fn get_file(url: &Url, restore_from_cache: bool) -> (Option<String>, String) {
+/// Load a text file from url and cache it.
+/// If restore_from_cache is true, only the cache is used.
+/// The first return value is the file content.
+/// It will be None if an error has occured.
+/// The second value is a combined error message.
+async fn get_file(url: &Url, restore_from_cache: bool, cache_file: bool) -> (Option<String>, String) {
 	if url.scheme() == "file" {
 		let path = url.path();
 		info!("load file {path:?}");
@@ -281,12 +277,13 @@ async fn get_file(url: &Url, restore_from_cache: bool) -> (Option<String>, Strin
 					.error_for_status()?
 					.text()
 					.await?;
+				if cache_file {
 				if let Err(err) = write(&path, &resp)
 					.await
 					.with_context(|| format!("failed to save to {path:?}"))
 				{
 					error!("{err:?}");
-				}
+				}}
 				Ok(resp)
 			}
 			.await;
@@ -493,6 +490,19 @@ fn main() {
 	Lazy::force(&CONFIG_PATH);
 	Lazy::force(&LIST_DIR);
 
+	let config = load_config();
+
+	if std::env::args().any(|x| x == "--validate") {
+		if !async_validate_config(config) {
+			error!("Config validation failed!");
+			std::process::exit(1);
+		}
+	} else  {
+		async_main(config);
+	}
+}
+
+fn load_config() -> Config {
 	info!("load config from {:?}", &*CONFIG_PATH);
 	let config = fs::read(&*CONFIG_PATH)
 		.with_context(|| format!("Failed to read {:?}", CONFIG_PATH.as_path()))
@@ -501,7 +511,42 @@ fn main() {
 		.with_context(|| "Failed to deserialize config")
 		.unwrap_or_else(|err| panic!("{err:?}"));
 	debug!("{:#?}", config);
-	async_main(config);
+
+	config
+}
+
+#[tokio::main]
+async fn async_validate_config(config: Config) -> bool{
+	let mut validated = true;
+	//Allow List
+	for list in config.blocklist.allow_list {
+		let (file_content, error_message) = get_file(&list, false, false).await;
+		if let Some(content) = file_content {
+			if let Err(err) = parser::Blocklist::parse(list.path(), &content) {
+				error!("{}", err.msg());
+				validated = false;
+			}
+		} else {
+			error!("{error_message}");
+			validated = false;
+		}
+	}
+
+	//Block List
+	for list in config.blocklist.lists {
+		let (file_content, error_message) = get_file(&list, false, false).await;
+		if let Some(content) = file_content {
+			if let Err(err) = parser::Blocklist::parse(list.path(), &content) {
+				error!("{}", err.msg());
+				validated = false;
+			}
+		} else {
+			error!("{error_message}");
+			validated = false;
+		}
+	}
+
+	validated
 }
 
 #[cfg(test)]