Client: detect apt install candidate for resolvconf packages

client/install_client.sh

@@ -170,12 +170,19 @@ detect_client_lan_subnets() {
 }
 
 install_packages() {
+  pkg_has_install_candidate() {
+    local pkg="$1"
+    local candidate
+    candidate="$(apt-cache policy "$pkg" 2>/dev/null | awk '/Candidate:/ {print $2; exit}')"
+    [[ -n "$candidate" && "$candidate" != "(none)" ]]
+  }
+
   apt_install_if_missing wireguard wireguard-tools iproute2 openssh-client sshpass ca-certificates
 
   if ! command -v resolvconf >/dev/null 2>&1; then
-    if apt-cache show openresolv >/dev/null 2>&1; then
+    if pkg_has_install_candidate openresolv; then
       apt_install_if_missing openresolv
-    elif apt-cache show resolvconf >/dev/null 2>&1; then
+    elif pkg_has_install_candidate resolvconf; then
       apt_install_if_missing resolvconf
     else
       log_warn "Пакеты openresolv/resolvconf недоступны. DNS-строка в wg0.conf будет пропущена."