Add local/virtual MAC address detection

netenv/mac.go

@@ -0,0 +1,81 @@
+package netenv
+
+import (
+	"bytes"
+	"net"
+)
+
+var (
+	// UnspecifiedHardwareAddr defines the "unspecified" MAC address.
+	UnspecifiedHardwareAddr = net.HardwareAddr{0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
+
+	// virtualMACPrefixes holds MAC address prefixes specifically linked to
+	// virtualization solutions.
+	virtualMACPrefixes = []net.HardwareAddr{
+		// Mixed
+		{0x00, 0x16, 0x3E}, // Xen
+		{0x00, 0x18, 0x51}, // SWsoft
+		{0x00, 0x1C, 0x42}, // Parallels Virtual Machine
+		{0x02, 0x42},       // Docker
+		{0x50, 0x6B, 0x8D}, // Nutanix AHV
+		{0x52, 0x54, 0x00}, // KVM VMs
+		{0x54, 0x52},       // KVM (proxmox)
+		{0x58, 0x9C, 0xFC}, // bhyve by FreebsdF
+
+		// Microsoft
+		{0x00, 0x03, 0xFF}, // Microsoft Virtual PC
+		{0x00, 0x15, 0x5D}, // Hyper-V (by Microsoft for VMs)
+		{0x00, 0x1D, 0xD8}, // Microsoft SCVMM (actual space at 00:1D:D8:B7:1C:00 - 00:1D:D8:F4:1F:FF)
+
+		// Oracle
+		{0x00, 0x0F, 0x4B}, // Oracle Virtual Iron 4
+		{0x00, 0x14, 0x4F}, // Oracle VM Server for SPARC
+		{0x00, 0x21, 0xF6}, // Oracle VirtualBox 3.3
+		{0x08, 0x00, 0x27}, // Oracle VirtualBox 5.2
+		{0x52, 0x54, 0x00}, // Oracle VirtualBox 5.2
+
+		// VMWare
+		{0x00, 0x05, 0x69}, // VMWare ESX, GSX Server
+		{0x00, 0x0C, 0x29}, // VMWare vSphere, Workstation, Horizon
+		{0x00, 0x1C, 0x14}, // VMWare
+		{0x00, 0x50, 0x56}, // VMWare vSphere, Workstation, ESX Server
+	}
+
+	// Other available sources:
+	// https://standards-oui.ieee.org/oui/oui.txt
+	// https://gitlab.com/wireshark/wireshark/-/raw/master/manuf
+	// https://macaddress.io/faq
+
+	// This website has some detection for special use cases, such as docker:
+	// https://maclookup.app/
+
+	// macAddressUniversalLocalBit defines whether the address is universally or
+	// locally administered address.
+	macAddressUniversalLocalBit byte = 0x02
+)
+
+// HardwareAddressIsLocal returns whether the given HardwareAddr is part of a
+// localhost-only network with a certain probability.
+// If checkLocalBit is enabled, true is returned when the local bit of the
+// address is set. This is might lead to many false positivies, but is a
+// helpful workaround or quick fix.
+func HardwareAddressIsLocal(hwAddr net.HardwareAddr, checkLocalBit bool) bool {
+	// Check input.
+	if len(hwAddr) == 0 {
+		return false
+	}
+
+	// Check for the Universal/Local bit.
+	if checkLocalBit && hwAddr[0]&macAddressUniversalLocalBit == macAddressUniversalLocalBit {
+		return true
+	}
+
+	// Check if any of the virtual prefixes match.
+	for _, prefix := range virtualMACPrefixes {
+		if bytes.HasPrefix(hwAddr, prefix) {
+			return true
+		}
+	}
+
+	return false
+}