Port to Windows ARM64 (MSVC)

CMakeLists.txt

@@ -0,0 +1,110 @@
+cmake_minimum_required(VERSION 3.20)
+project(hans VERSION 1.1 LANGUAGES C CXX)
+
+# Remove all debug information from Release binaries
+set(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT "")
+string(REPLACE "/Zi" "" CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}")
+string(REPLACE "/Zi" "" CMAKE_C_FLAGS_RELEASE   "${CMAKE_C_FLAGS_RELEASE}")
+string(REPLACE "/ZI" "" CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}")
+string(REPLACE "/ZI" "" CMAKE_C_FLAGS_RELEASE   "${CMAKE_C_FLAGS_RELEASE}")
+set(CMAKE_EXE_LINKER_FLAGS_RELEASE "/INCREMENTAL:NO /DEBUG:NONE /EMITPOGOPHASEINFO:NO")
+
+# ---------------------------------------------------------------------------
+# Language standard
+# ---------------------------------------------------------------------------
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_STANDARD_REQUIRED ON)
+
+# ---------------------------------------------------------------------------
+# MSVC-specific flags  (supports x64 and ARM64)
+# ---------------------------------------------------------------------------
+if(MSVC)
+    add_compile_options(
+        /W3
+        /wd4996   # deprecated CRT functions (_CRT_SECURE_NO_WARNINGS)
+        /wd4267   # size_t → int conversion (64-bit)
+        /wd4244   # intptr_t → int conversion (fd casts)
+        /wd4200   # nonstandard zero-size array (not used but silences noise)
+    )
+    add_compile_definitions(
+        WIN32                           # legacy guard used in original code
+        _WIN32                          # standard MSVC pre-define (explicit)
+        _CRT_SECURE_NO_WARNINGS
+        _WINSOCK_DEPRECATED_NO_WARNINGS
+        WIN32_LEAN_AND_MEAN
+        NOMINMAX                        # prevent windows.h min/max macros
+    )
+endif()
+
+# ---------------------------------------------------------------------------
+# Source files common to all platforms
+# ---------------------------------------------------------------------------
+set(COMMON_SOURCES
+    src/main.cpp
+    src/client.cpp
+    src/server.cpp
+    src/worker.cpp
+    src/tun.cpp
+    src/echo.cpp
+    src/auth.cpp
+    src/sha1.cpp
+    src/hans_time.cpp
+    src/exception.cpp
+    src/utility.cpp
+)
+
+# ---------------------------------------------------------------------------
+# Platform-specific TUN/TAP driver
+# ---------------------------------------------------------------------------
+if(WIN32)
+    # Native MSVC build — uses TAP-Windows (OpenVPN TAP driver)
+    list(APPEND COMMON_SOURCES
+        src/win32_compat.cpp
+        src/tun_dev_win32.c
+    )
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    list(APPEND COMMON_SOURCES src/tun_dev_linux.c)
+    add_compile_definitions(HAVE_LINUX_IF_TUN_H LINUX)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
+    list(APPEND COMMON_SOURCES src/tun_dev_freebsd.c)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")
+    list(APPEND COMMON_SOURCES src/tun_dev_openbsd.c)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+    list(APPEND COMMON_SOURCES src/tun_dev_utun.c)
+else()
+    list(APPEND COMMON_SOURCES src/tun_dev_generic.c)
+endif()
+
+# ---------------------------------------------------------------------------
+# Executable
+# ---------------------------------------------------------------------------
+add_executable(hans ${COMMON_SOURCES})
+
+target_include_directories(hans PRIVATE src)
+
+set_target_properties(hans PROPERTIES
+    LINK_FLAGS_RELEASE "/INCREMENTAL:NO /DEBUG:NONE"
+)
+
+# ---------------------------------------------------------------------------
+# Linker dependencies
+# ---------------------------------------------------------------------------
+if(WIN32)
+    target_link_libraries(hans PRIVATE
+        ws2_32          # Winsock2
+        iphlpapi        # IP helper API (used indirectly by Winsock)
+    )
+elseif(UNIX)
+    find_package(Threads REQUIRED)
+    target_link_libraries(hans PRIVATE Threads::Threads)
+    if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+        # tunemu mode would also need -lpcap, but utun mode does not
+    endif()
+endif()
+
+# ---------------------------------------------------------------------------
+# Install
+# ---------------------------------------------------------------------------
+install(TARGETS hans RUNTIME DESTINATION bin)

WIN-ARM64.md

@@ -0,0 +1,110 @@
+# Building Hans -- Windows ARM64 (MSVC)
+
+This document describes how to build Hans natively on **Windows ARM64** using Visual Studio and CMake. This replaces the legacy CYGWIN/Makefile build for x86.
+
+---
+
+## Requirements
+
+| Tool | Version | Notes |
+|---|---|---|
+| Visual Studio | 2026 Community (or 2022) | With **Desktop development with C++** workload |
+| CMake | Bundled with Visual Studio | Must be added to PATH |
+| TAP-Windows driver | Any | Included with [OpenVPN](https://openvpn.net/community-downloads/) |
+
+---
+
+## 1. Add CMake to PATH
+
+CMake ships with Visual Studio but is not added to PATH automatically.
+
+Open PowerShell as **Administrator** and run:
+
+```powershell
+$cmakePath = "C:\Program Files\Microsoft Visual Studio\18\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin"
+[Environment]::SetEnvironmentVariable("Path", $env:Path + ";$cmakePath", "Machine")
+```
+
+> For Visual Studio 2022, replace `\18\` with `\17\` or `\2022\` in the path above.
+
+Close and reopen PowerShell, then verify:
+
+```powershell
+cmake --version
+```
+
+---
+
+## 2. Configure the Build
+
+Open PowerShell, navigate to the project folder and run:
+
+```powershell
+cd C:\path\to\hans
+cmake -B build -A ARM64
+```
+
+You should see output ending with:
+```
+-- Build files have been written to: ...\hans\build
+```
+
+---
+
+## 3. Compile
+
+```powershell
+cmake --build build --config Release
+```
+
+The executable will be at:
+```
+build\Release\hans.exe
+```
+
+---
+
+## 4. Clean Build (if needed)
+
+If you are recompiling after source changes:
+
+```powershell
+Remove-Item -Recurse -Force build
+cmake -B build -A ARM64
+cmake --build build --config Release
+```
+
+---
+
+## 5. Verify No Debug Info (optional)
+
+To confirm the Release binary has no embedded debug information:
+
+```powershell
+& "C:\Program Files\Microsoft Visual Studio\18\Community\VC\Tools\MSVC\14.50.35717\bin\Hostarm64\arm64\dumpbin.exe" /headers build\Release\hans.exe | Select-String "debug"
+```
+
+Expected output:
+```
+0 [       0] RVA [size] of Debug Directory
+```
+
+---
+
+## Runtime Requirements
+
+The **TAP-Windows** driver must be installed before running `hans.exe`. It is bundled with [OpenVPN](https://openvpn.net/community-downloads/) -- installing OpenVPN is sufficient.
+
+---
+
+## Windows-specific Files
+
+These files were added for the Windows/MSVC port and have no effect on Linux builds:
+
+| File | Purpose |
+|---|---|
+| `src/win32_compat.h` / `.cpp` | POSIX compatibility layer (sockets, threads) |
+| `src/tun_dev_win32.c` | TAP-Windows adapter driver with Overlapped I/O |
+| `CMakeLists.txt` | CMake build system replacing the original Makefile |
+
+> `src/hans_time.h` / `hans_time.cpp` were renamed from `time.h` / `time.cpp` to avoid a naming conflict with the MSVC system header `<time.h>`.

src/auth.cpp

@@ -17,11 +17,18 @@
  *
  */
 
+/* win32_compat.h must be the first include on Windows. */
+#ifdef _WIN32
+#  include "win32_compat.h"
+#endif
+
 #include "auth.h"
 #include "sha1.h"
 #include "utility.h"
 
-#include <arpa/inet.h>
+#ifndef _WIN32
+#  include <arpa/inet.h>
+#endif
 
 Auth::Auth(const std::string &passphrase)
     : passphrase(passphrase)

src/client.cpp

@@ -17,16 +17,24 @@
  *
  */
 
+/* win32_compat.h must be the first include on Windows. */
+#ifdef _WIN32
+#  include "win32_compat.h"
+#endif
+
 #include "client.h"
 #include "server.h"
 #include "exception.h"
 #include "config.h"
 #include "utility.h"
 
 #include <string.h>
-#include <arpa/inet.h>
-#include <netinet/in.h>
-#include <syslog.h>
+
+#ifndef _WIN32
+#  include <arpa/inet.h>
+#  include <netinet/in.h>
+#  include <syslog.h>
+#endif
 
 using std::vector;
 using std::string;

src/echo.cpp

@@ -17,28 +17,39 @@
  *
  */
 
+/* win32_compat.h must be the first include on Windows. */
+#ifdef _WIN32
+#  include "win32_compat.h"
+#endif
+
 #include "echo.h"
 #include "exception.h"
 
-#include <sys/socket.h>
-#include <sys/types.h>
-#include <netinet/in_systm.h>
-#include <netinet/in.h>
-#include <netinet/ip.h>
-#include <arpa/inet.h>
-#include <unistd.h>
-#include <errno.h>
-#include <syslog.h>
+#ifdef _WIN32
+   /* struct ip defined in win32_compat.h; winsock2 provides socket API */
+#  define CLOSE_SOCKET(fd)  closesocket((SOCKET)(uintptr_t)(fd))
+#else
+#  include <sys/socket.h>
+#  include <sys/types.h>
+#  include <netinet/in_systm.h>
+#  include <netinet/in.h>
+#  include <netinet/ip.h>
+#  include <arpa/inet.h>
+#  include <unistd.h>
+#  include <errno.h>
+#  include <syslog.h>
+#  define CLOSE_SOCKET(fd)  close(fd)
+#endif
+
 #include <stdio.h>
 #include <string.h>
-#include <sys/types.h>
 
 typedef ip IpHeader;
 
 Echo::Echo(int maxPayloadSize)
 {
-    fd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
-    if (fd == -1)
+    fd = (hans_fd_t)socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
+    if (fd == (hans_fd_t)-1)
         throw Exception("creating icmp socket", true);
 
     bufferSize = maxPayloadSize + headerSize();
@@ -48,7 +59,7 @@ Echo::Echo(int maxPayloadSize)
 
 Echo::~Echo()
 {
-    close(fd);
+    CLOSE_SOCKET(fd);
 }
 
 int Echo::headerSize()
@@ -73,7 +84,10 @@ void Echo::send(int payloadLength, uint32_t realIp, bool reply, uint16_t id, uin
     header->chksum = 0;
     header->chksum = icmpChecksum(sendBuffer.data() + sizeof(IpHeader), payloadLength + sizeof(EchoHeader));
 
-    int result = sendto(fd, sendBuffer.data() + sizeof(IpHeader), payloadLength + sizeof(EchoHeader), 0, (struct sockaddr *)&target, sizeof(struct sockaddr_in));
+    int result = sendto((SOCKET)(uintptr_t)fd,
+                        sendBuffer.data() + sizeof(IpHeader),
+                        payloadLength + (int)sizeof(EchoHeader), 0,
+                        (struct sockaddr *)&target, sizeof(struct sockaddr_in));
     if (result == -1)
         syslog(LOG_ERR, "error sending icmp packet: %s", strerror(errno));
 }
@@ -83,7 +97,10 @@ int Echo::receive(uint32_t &realIp, bool &reply, uint16_t &id, uint16_t &seq)
     struct sockaddr_in source;
     int source_addr_len = sizeof(struct sockaddr_in);
 
-    int dataLength = recvfrom(fd, receiveBuffer.data(), bufferSize, 0, (struct sockaddr *)&source, (socklen_t *)&source_addr_len);
+    int dataLength = recvfrom((SOCKET)(uintptr_t)fd,
+                              receiveBuffer.data(), bufferSize, 0,
+                              (struct sockaddr *)&source,
+                              (socklen_t *)&source_addr_len);
     if (dataLength == -1)
     {
         syslog(LOG_ERR, "error receiving icmp packet: %s", strerror(errno));

src/echo.h

@@ -24,13 +24,23 @@
 #include <vector>
 #include <stdint.h>
 
+/* hans_fd_t: intptr_t on Windows (covers 64-bit SOCKET), int on POSIX */
+#ifdef _WIN32
+#  include "win32_compat.h"
+#else
+#  ifndef HANS_FD_T_DEFINED
+#  define HANS_FD_T_DEFINED
+   typedef int hans_fd_t;
+#  endif
+#endif
+
 class Echo
 {
 public:
     Echo(int maxPayloadSize);
     ~Echo();
 
-    int getFd() { return fd; }
+    hans_fd_t getFd() { return fd; }
 
     void send(int payloadLength, uint32_t realIp, bool reply, uint16_t id, uint16_t seq);
     int receive(uint32_t &realIp, bool &reply, uint16_t &id, uint16_t &seq);
@@ -51,7 +61,7 @@ class Echo
 
     uint16_t icmpChecksum(const char *data, int length);
 
-    int fd;
+    hans_fd_t fd;
     int bufferSize;
     std::vector<char> sendBuffer;
     std::vector<char> receiveBuffer;