Auto-select usable scan interfaces
This commit is contained in:
Corsair-cxs
parent
1c223859df
commit
d92b0f6b0e
2 changed files with 268 additions and 10 deletions
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@ -2,7 +2,11 @@ package arp
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import (
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"log/slog"
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"net"
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"os"
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"os/exec"
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"sort"
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"strconv"
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"strings"
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"time"
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@ -72,17 +76,13 @@ func Scan(ifaces, args string, strs []string) []models.Host {
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var foundHosts = []models.Host{}
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arpArgs = args
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if ifaces != "" {
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p = resolveScanInterfaces(ifaces)
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for _, iface := range p {
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slog.Debug("Scanning interface " + iface)
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text = scanIface(iface)
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slog.Debug("Found IPs: \n" + text)
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p = strings.Split(ifaces, " ")
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for _, iface := range p {
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slog.Debug("Scanning interface " + iface)
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text = scanIface(iface)
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slog.Debug("Found IPs: \n" + text)
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foundHosts = append(foundHosts, parseOutput(text, iface)...)
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}
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foundHosts = append(foundHosts, parseOutput(text, iface)...)
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}
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for _, s := range strs {
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@ -96,3 +96,192 @@ func Scan(ifaces, args string, strs []string) []models.Host {
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return foundHosts
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}
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func resolveScanInterfaces(ifaces string) []string {
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configured := strings.Fields(ifaces)
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available := usableInterfaceMap()
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auto := autoScanInterfaces(available)
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selected, invalid, usedAuto := selectScanInterfaces(configured, available, auto)
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if len(invalid) > 0 {
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slog.Warn("Ignoring unavailable scan interfaces", "ifaces", strings.Join(invalid, " "))
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}
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if usedAuto && len(selected) > 0 {
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slog.Warn("Using auto-detected scan interfaces", "ifaces", strings.Join(selected, " "))
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}
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return selected
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}
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func selectScanInterfaces(configured []string, available map[string]bool, auto []string) ([]string, []string, bool) {
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if len(configured) == 0 {
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return uniqueStrings(auto), nil, len(auto) > 0
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}
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var selected []string
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var invalid []string
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for _, iface := range configured {
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if available[iface] {
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selected = appendUniqueString(selected, iface)
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continue
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}
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invalid = appendUniqueString(invalid, iface)
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}
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if len(selected) > 0 {
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return selected, invalid, false
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}
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return uniqueStrings(auto), invalid, len(auto) > 0
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}
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func usableInterfaceMap() map[string]bool {
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interfaces, err := net.Interfaces()
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if err != nil {
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slog.Warn("Cannot list network interfaces", "err", err)
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return nil
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}
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available := make(map[string]bool)
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for _, iface := range interfaces {
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if isUsableInterface(iface) {
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available[iface.Name] = true
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}
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}
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return available
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}
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func isUsableInterface(iface net.Interface) bool {
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if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
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return false
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}
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addrs, err := iface.Addrs()
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if err != nil {
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slog.Debug("Cannot list interface addresses", "iface", iface.Name, "err", err)
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return false
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}
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for _, addr := range addrs {
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if hasUsableIPv4(addr) {
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return true
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}
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}
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return false
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}
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func hasUsableIPv4(addr net.Addr) bool {
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ipNet, ok := addr.(*net.IPNet)
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if !ok {
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return false
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}
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ip := ipNet.IP.To4()
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return ip != nil && !ip.IsLoopback() && !ip.IsLinkLocalUnicast()
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}
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func autoScanInterfaces(available map[string]bool) []string {
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if len(available) == 0 {
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return nil
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}
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ifaces := defaultRouteInterfaces(available)
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if len(ifaces) > 0 {
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return ifaces
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}
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for iface := range available {
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if isVirtualInterface(iface) {
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continue
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}
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ifaces = append(ifaces, iface)
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}
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sort.Strings(ifaces)
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return ifaces
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}
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func defaultRouteInterfaces(available map[string]bool) []string {
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data, err := os.ReadFile("/proc/net/route")
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if err != nil {
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slog.Debug("Cannot read default routes", "err", err)
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return nil
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}
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var ifaces []string
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minMetric := -1
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for _, line := range strings.Split(string(data), "\n")[1:] {
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fields := strings.Fields(line)
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if len(fields) < 7 || fields[1] != "00000000" {
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continue
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}
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iface := fields[0]
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if !available[iface] || isVirtualInterface(iface) {
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continue
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}
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metric, err := strconv.Atoi(fields[6])
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if err != nil {
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metric = 0
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}
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switch {
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case minMetric == -1 || metric < minMetric:
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minMetric = metric
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ifaces = []string{iface}
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case metric == minMetric:
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ifaces = appendUniqueString(ifaces, iface)
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}
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}
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sort.Strings(ifaces)
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return ifaces
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}
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func isVirtualInterface(iface string) bool {
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prefixes := []string{
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"br-",
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"docker",
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"lxc",
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"tailscale",
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"tap",
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"tun",
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"vboxnet",
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"veth",
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"virbr",
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"vmnet",
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"wg",
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}
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for _, prefix := range prefixes {
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if strings.HasPrefix(iface, prefix) {
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return true
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}
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}
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return false
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}
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func uniqueStrings(values []string) []string {
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var out []string
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for _, value := range values {
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out = appendUniqueString(out, value)
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}
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return out
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}
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func appendUniqueString(values []string, value string) []string {
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if value == "" {
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return values
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}
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for _, item := range values {
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if item == value {
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return values
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}
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}
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return append(values, value)
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}
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69
backend/internal/arp/arpscan_test.go
Normal file
69
backend/internal/arp/arpscan_test.go
Normal file
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@ -0,0 +1,69 @@
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package arp
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import (
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"reflect"
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"testing"
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)
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func TestSelectScanInterfacesKeepsValidConfiguredInterfaces(t *testing.T) {
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available := map[string]bool{
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"enp6s0": true,
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"wlo1": true,
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}
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selected, invalid, usedAuto := selectScanInterfaces(
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[]string{"enp6s0", "missing0"},
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available,
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[]string{"wlo1"},
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)
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if !reflect.DeepEqual(selected, []string{"enp6s0"}) {
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t.Fatalf("selected = %#v, want enp6s0", selected)
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}
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if !reflect.DeepEqual(invalid, []string{"missing0"}) {
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t.Fatalf("invalid = %#v, want missing0", invalid)
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}
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if usedAuto {
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t.Fatal("usedAuto = true, want false")
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}
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}
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func TestSelectScanInterfacesFallsBackWhenAllConfiguredInterfacesAreInvalid(t *testing.T) {
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available := map[string]bool{
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"enp6s0": true,
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}
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selected, invalid, usedAuto := selectScanInterfaces(
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[]string{"enP8p1s0"},
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available,
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[]string{"enp6s0"},
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)
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if !reflect.DeepEqual(selected, []string{"enp6s0"}) {
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t.Fatalf("selected = %#v, want enp6s0", selected)
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}
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if !reflect.DeepEqual(invalid, []string{"enP8p1s0"}) {
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t.Fatalf("invalid = %#v, want enP8p1s0", invalid)
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}
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if !usedAuto {
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t.Fatal("usedAuto = false, want true")
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}
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}
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func TestSelectScanInterfacesUsesAutoWhenConfigIsBlank(t *testing.T) {
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selected, invalid, usedAuto := selectScanInterfaces(
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nil,
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map[string]bool{"enp6s0": true},
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[]string{"enp6s0"},
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)
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if !reflect.DeepEqual(selected, []string{"enp6s0"}) {
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t.Fatalf("selected = %#v, want enp6s0", selected)
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}
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if len(invalid) != 0 {
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t.Fatalf("invalid = %#v, want empty", invalid)
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}
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if !usedAuto {
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t.Fatal("usedAuto = false, want true")
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}
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}
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