Handle IPv6-less hosts in ip6tables shim

qbittorrent/rootfs/usr/local/sbin/iptables-restore

@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+REAL_IPTABLES_RESTORE="/sbin/iptables-restore"
+if [[ ! -x "${REAL_IPTABLES_RESTORE}" ]]; then
+    REAL_IPTABLES_RESTORE="/usr/sbin/iptables-restore"
+fi
+
+cleanup() {
+    [[ -n "${RULES_FILE:-}" && -f "${RULES_FILE}" ]] && rm -f "${RULES_FILE}"
+    [[ -n "${SANITIZED_FILE:-}" && -f "${SANITIZED_FILE}" ]] && rm -f "${SANITIZED_FILE}"
+}
+trap cleanup EXIT
+
+RULES_FILE="$(mktemp)"
+cat > "${RULES_FILE}"
+
+# First attempt with the original ruleset
+if output="$(${REAL_IPTABLES_RESTORE} "$@" < "${RULES_FILE}" 2>&1)"; then
+    [[ -n "${output}" ]] && printf '%s\n' "${output}" >&2
+    exit 0
+fi
+status=$?
+
+# Retry without comment matches if the kernel is missing the comment module
+SANITIZED_FILE="$(mktemp)"
+sed -E 's/-m[[:space:]]+comment[[:space:]]+--comment[[:space:]]+"[^"]*"//g' "${RULES_FILE}" > "${SANITIZED_FILE}"
+
+if retry_output="$(${REAL_IPTABLES_RESTORE} "$@" < "${SANITIZED_FILE}" 2>&1)"; then
+    printf '%s\n' "iptables-restore failed with comment matches; reapplied without comments." >&2
+    printf '%s\n' "Original error: ${output}" >&2
+    [[ -n "${retry_output}" ]] && printf '%s\n' "${retry_output}" >&2
+    exit 0
+fi
+retry_status=$?
+
+# Final fallback: try legacy backend if available
+for legacy in /sbin/iptables-restore-legacy /usr/sbin/iptables-restore-legacy; do
+    if [[ -x "${legacy}" ]]; then
+        if legacy_output="$(${legacy} "$@" < "${RULES_FILE}" 2>&1)"; then
+            printf '%s\n' "iptables-restore failed; succeeded using legacy backend." >&2
+            printf '%s\n' "Original error: ${output}" >&2
+            [[ -n "${legacy_output}" ]] && printf '%s\n' "${legacy_output}" >&2
+            exit 0
+        fi
+    fi
+done
+
+printf '%s\n' "iptables-restore failed and fallbacks were unsuccessful." >&2
+printf '%s\n' "Original error: ${output}" >&2
+printf '%s\n' "Sanitized retry error: ${retry_output}" >&2
+exit ${retry_status}