Check resolve.conf for systemd-resolved DNS server

1 files changed, 18 insertions, 1 deletions

diff --git a/talpid-core/src/security/linux/dns/systemd_resolved.rs b/talpid-core/src/security/linux/dns/systemd_resolved.rs
index 72743d8913..78e55a048b 100644
--- a/talpid-core/src/security/linux/dns/systemd_resolved.rs
+++ b/talpid-core/src/security/linux/dns/systemd_resolved.rs
@@ -14,6 +14,7 @@ use self::dbus::{BusType, Interface, Member, MessageItem, MessageItemArray, Sign
 use super::super::iface_index;
 use super::{resolv_conf, RESOLV_CONF_PATH};
 
+
 error_chain! {
     errors {
         NoSystemdResolved {
@@ -42,6 +43,8 @@ error_chain! {
 }
 
 const DYNAMIC_RESOLV_CONF_PATH: &str = "/run/systemd/resolve/resolv.conf";
+const RESOLVED_DNS_SERVER_ADDRESS: [u8; 4] = [127, 0, 0, 53];
+
 const RESOLVED_BUS: &str = "org.freedesktop.resolve1";
 const RPC_TIMEOUT_MS: i32 = 1000;
 
@@ -86,7 +89,7 @@ impl SystemdResolved {
 
     fn ensure_resolved_is_active() -> Result<()> {
         ensure!(
-            Self::resolv_conf_is_resolved_symlink(),
+            Self::resolv_conf_is_resolved_symlink() || Self::resolv_conf_has_resolved_dns()?,
             ErrorKind::NoSystemdResolved
         );
 
@@ -99,6 +102,20 @@ impl SystemdResolved {
             .unwrap_or_else(|_| false)
     }
 
+    fn resolv_conf_has_resolved_dns() -> Result<bool> {
+        let resolv_conf_contents =
+            fs::read_to_string(RESOLV_CONF_PATH).chain_err(|| ErrorKind::NoSystemdResolved)?;
+        let parsed_resolv_conf = resolv_conf::Config::parse(resolv_conf_contents)
+            .chain_err(|| ErrorKind::NoSystemdResolved)?;
+        let resolved_dns_server =
+            resolv_conf::ScopedIp::V4(Ipv4Addr::from(RESOLVED_DNS_SERVER_ADDRESS));
+
+        Ok(parsed_resolv_conf
+            .nameservers
+            .into_iter()
+            .any(|nameserver| nameserver == resolved_dns_server))
+    }
+
     fn as_manager_object<'a>(&'a self) -> dbus::ConnPath<'a, &'a dbus::Connection> {
         self.dbus_connection
             .with_path(RESOLVED_BUS, "/org/freedesktop/resolve1", RPC_TIMEOUT_MS)