proxmox/proxmox-dns-api/src/resolv_conf.rs
Maximiliano Sandoval 9693ceca7a dns-api: remove lazy-static dependency
Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
2024-08-14 10:33:42 +02:00

140 lines
3.8 KiB
Rust

use std::sync::{Arc, LazyLock, Mutex};
use anyhow::Error;
use const_format::concatcp;
use proxmox_config_digest::ConfigDigest;
use regex::Regex;
use proxmox_sys::fs::file_get_contents;
use proxmox_sys::fs::replace_file;
use proxmox_sys::fs::CreateOptions;
use proxmox_schema::api_types::IPRE_STR;
use super::DeletableResolvConfProperty;
use super::ResolvConf;
use super::ResolvConfWithDigest;
static RESOLV_CONF_FN: &str = "/etc/resolv.conf";
/// Read DNS configuration from '/etc/resolv.conf'.
pub fn read_etc_resolv_conf(
expected_digest: Option<&ConfigDigest>,
) -> Result<ResolvConfWithDigest, Error> {
let mut config = ResolvConf::default();
let mut nscount = 0;
let raw = file_get_contents(RESOLV_CONF_FN)?;
let digest = ConfigDigest::from_slice(&raw);
digest.detect_modification(expected_digest)?;
let data = String::from_utf8(raw)?;
static DOMAIN_REGEX: LazyLock<Regex> =
LazyLock::new(|| Regex::new(r"^\s*(?:search|domain)\s+(\S+)\s*").unwrap());
static SERVER_REGEX: LazyLock<Regex> =
LazyLock::new(|| Regex::new(concatcp!(r"^\s*nameserver\s+(", IPRE_STR, r")\s*")).unwrap());
let mut options = String::new();
for line in data.lines() {
if let Some(caps) = DOMAIN_REGEX.captures(line) {
config.search = Some(caps[1].to_owned());
} else if let Some(caps) = SERVER_REGEX.captures(line) {
nscount += 1;
if nscount > 3 {
continue;
};
let nameserver = Some(caps[1].to_owned());
match nscount {
1 => config.dns1 = nameserver,
2 => config.dns2 = nameserver,
3 => config.dns3 = nameserver,
_ => continue,
}
} else {
if !options.is_empty() {
options.push('\n');
}
options.push_str(line);
}
}
if !options.is_empty() {
config.options = Some(options);
}
Ok(ResolvConfWithDigest { config, digest })
}
/// Update DNS configuration, write result back to '/etc/resolv.conf'.
pub fn update_dns(
update: ResolvConf,
delete: Option<Vec<DeletableResolvConfProperty>>,
digest: Option<ConfigDigest>,
) -> Result<(), Error> {
static MUTEX: LazyLock<Arc<Mutex<()>>> = LazyLock::new(|| Arc::new(Mutex::new(())));
let _guard = MUTEX.lock();
let ResolvConfWithDigest { mut config, .. } = read_etc_resolv_conf(digest.as_ref())?;
if let Some(delete) = delete {
for delete_prop in delete {
match delete_prop {
DeletableResolvConfProperty::Dns1 => {
config.dns1 = None;
}
DeletableResolvConfProperty::Dns2 => {
config.dns2 = None;
}
DeletableResolvConfProperty::Dns3 => {
config.dns3 = None;
}
}
}
}
if update.search.is_some() {
config.search = update.search;
}
if update.dns1.is_some() {
config.dns1 = update.dns1;
}
if update.dns2.is_some() {
config.dns2 = update.dns2;
}
if update.dns3.is_some() {
config.dns3 = update.dns3;
}
let mut data = String::new();
use std::fmt::Write as _;
if let Some(search) = config.search {
let _ = writeln!(data, "search {}", search);
}
if let Some(dns1) = config.dns1 {
let _ = writeln!(data, "nameserver {}", dns1);
}
if let Some(dns2) = config.dns2 {
let _ = writeln!(data, "nameserver {}", dns2);
}
if let Some(dns3) = config.dns3 {
let _ = writeln!(data, "nameserver {}", dns3);
}
if let Some(options) = config.options {
data.push_str(&options);
}
replace_file(RESOLV_CONF_FN, data.as_bytes(), CreateOptions::new(), true)?;
Ok(())
}