Add native Windows build of meshtasticd (#11031)

src/platform/portduino/WindowsMacAddr.cpp

@@ -0,0 +1,54 @@
+#if defined(ARCH_PORTDUINO) && defined(_WIN32)
+
+// Host-MAC lookup for getMacAddr(), replacing BlueZ on Linux and en0 on macOS.
+// Isolated TU: <iphlpapi.h> needs the header trims the env sets, and undoes them here.
+#undef WIN32_LEAN_AND_MEAN
+#undef NOUSER
+#undef NOGDI
+
+// Order is load-bearing, hence the blank lines: winsock2.h must precede
+// windows.h, which would otherwise pull in the colliding winsock v1 header.
+#include <winsock2.h>
+
+#include <windows.h>
+
+#include <iphlpapi.h>
+
+#include <cstring>
+#include <memory>
+#include <stdint.h>
+
+// Fill dmac with the first up, non-loopback adapter's physical address, else
+// return false. Adapter order is stable across reboots, so the identity persists.
+bool portduinoWindowsPrimaryMac(uint8_t *dmac)
+{
+    const ULONG flags = GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME;
+
+    ULONG bufLen = 15000; // starting size recommended by the API docs
+    std::unique_ptr<char[]> buf(new char[bufLen]);
+    auto *addrs = reinterpret_cast<IP_ADAPTER_ADDRESSES *>(buf.get());
+
+    ULONG ret = GetAdaptersAddresses(AF_UNSPEC, flags, nullptr, addrs, &bufLen);
+    if (ret == ERROR_BUFFER_OVERFLOW) {
+        // bufLen now holds the required size; retry once.
+        buf.reset(new char[bufLen]);
+        addrs = reinterpret_cast<IP_ADAPTER_ADDRESSES *>(buf.get());
+        ret = GetAdaptersAddresses(AF_UNSPEC, flags, nullptr, addrs, &bufLen);
+    }
+    if (ret != NO_ERROR)
+        return false;
+
+    for (auto *a = addrs; a != nullptr; a = a->Next) {
+        if (a->IfType == IF_TYPE_SOFTWARE_LOOPBACK)
+            continue;
+        if (a->OperStatus != IfOperStatusUp)
+            continue;
+        if (a->PhysicalAddressLength != 6)
+            continue;
+        std::memcpy(dmac, a->PhysicalAddress, 6);
+        return true;
+    }
+    return false;
+}
+
+#endif // ARCH_PORTDUINO && _WIN32