89 lines
2.3 KiB
Go
89 lines
2.3 KiB
Go
// Copyright 2026 Alibaba Group
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package security
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import (
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"fmt"
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"net"
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"slices"
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"strings"
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)
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// virtualMACPrefixes lists MAC address prefixes commonly used by
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// hypervisors, Docker, and VPN adapters.
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var virtualMACPrefixes = []string{
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"00:00:00",
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"02:42:",
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"02:00:",
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"fe:ff:",
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"00:50:56",
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"00:0c:29",
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"00:1c:42",
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"08:00:27",
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"52:54:00",
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}
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var networkInterfaces = net.Interfaces
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func isVirtualMAC(mac string) bool {
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for _, p := range virtualMACPrefixes {
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if strings.HasPrefix(mac, p) {
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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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// selectMAC picks the best MAC from the given interface list.
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// Physical NICs are preferred; virtual MACs are used as fallback.
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func selectMAC(ifaces []net.Interface) (string, error) {
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var physical, virtual []string
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for _, iface := range ifaces {
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if iface.Flags&net.FlagLoopback != 0 {
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continue
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}
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hw := iface.HardwareAddr
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if len(hw) == 0 {
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continue
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}
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s := strings.ToLower(hw.String())
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if isVirtualMAC(s) {
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virtual = append(virtual, s)
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} else {
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physical = append(physical, s)
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}
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}
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if len(physical) > 0 {
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slices.Sort(physical)
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return physical[0], nil
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}
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if len(virtual) > 0 {
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slices.Sort(virtual)
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return virtual[0], nil
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}
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return "", fmt.Errorf("no NIC MAC address found (no network interfaces available)")
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}
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// GetMACAddress returns the first physical (non-loopback, non-virtual) MAC
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// address, sorted lexicographically for determinism. If no physical NIC is
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// found (e.g. inside a Docker container), it falls back to the first
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// non-loopback virtual MAC address so that token encryption still works.
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func GetMACAddress() (string, error) {
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ifaces, err := networkInterfaces()
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if err != nil {
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return "", fmt.Errorf("enumerating network interfaces: %w", err)
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}
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return selectMAC(ifaces)
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}
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