New upstream version 2.5~beta1upstream/2.5_beta1

1 files changed, 1215 insertions, 0 deletions

diff --git a/src/openvpnmsica/openvpnmsica.c b/src/openvpnmsica/openvpnmsica.c
new file mode 100644
index 0000000..31e90bd
--- /dev/null
+++ b/src/openvpnmsica/openvpnmsica.c
@@ -0,0 +1,1215 @@
+/*
+ *  openvpnmsica -- Custom Action DLL to provide OpenVPN-specific support to MSI packages
+ *                  https://community.openvpn.net/openvpn/wiki/OpenVPNMSICA
+ *
+ *  Copyright (C) 2018-2020 Simon Rozman <simon@rozman.si>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#elif defined(_MSC_VER)
+#include <config-msvc.h>
+#endif
+#include <winsock2.h> /* Must be included _before_ <windows.h> */
+
+#include "openvpnmsica.h"
+#include "msica_arg.h"
+#include "msiex.h"
+
+#include "../tapctl/basic.h"
+#include "../tapctl/error.h"
+#include "../tapctl/tap.h"
+
+#include <windows.h>
+#include <iphlpapi.h>
+#include <malloc.h>
+#include <memory.h>
+#include <msiquery.h>
+#include <shellapi.h>
+#include <shlwapi.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <tchar.h>
+
+#ifdef _MSC_VER
+#pragma comment(lib, "advapi32.lib")
+#pragma comment(lib, "iphlpapi.lib")
+#pragma comment(lib, "shell32.lib")
+#pragma comment(lib, "shlwapi.lib")
+#pragma comment(lib, "version.lib")
+#endif
+
+
+/**
+ * Local constants
+ */
+
+#define MSICA_ADAPTER_TICK_SIZE (16*1024) /** Amount of tick space to reserve for one TAP/TUN adapter creation/deletition. */
+
+
+/**
+ * Joins an argument sequence and sets it to the MSI property.
+ *
+ * @param hInstall      Handle to the installation provided to the DLL custom action
+ *
+ * @param szProperty    MSI property name to set to the joined argument sequence.
+ *
+ * @param seq           The argument sequence.
+ *
+ * @return ERROR_SUCCESS on success; An error code otherwise
+ */
+static UINT
+setup_sequence(
+    _In_ MSIHANDLE hInstall,
+    _In_z_ LPCTSTR szProperty,
+    _In_ struct msica_arg_seq *seq)
+{
+    UINT uiResult;
+    LPTSTR szSequence = msica_arg_seq_join(seq);
+    uiResult = MsiSetProperty(hInstall, szProperty, szSequence);
+    free(szSequence);
+    if (uiResult != ERROR_SUCCESS)
+    {
+        SetLastError(uiResult); /* MSDN does not mention MsiSetProperty() to set GetLastError(). But we do have an error code. Set last error manually. */
+        msg(M_NONFATAL | M_ERRNO, "%s: MsiSetProperty(\"%" PRIsLPTSTR "\") failed", __FUNCTION__, szProperty);
+        return uiResult;
+    }
+    return ERROR_SUCCESS;
+}
+
+
+#ifdef _DEBUG
+
+/**
+ * Pops up a message box creating a time window to attach a debugger to the installer process in
+ * order to debug custom actions.
+ *
+ * @param szFunctionName  Function name that triggered the pop-up. Displayed in message box's
+ *                        title.
+ */
+static void
+_debug_popup(_In_z_ LPCTSTR szFunctionName)
+{
+    TCHAR szTitle[0x100], szMessage[0x100+MAX_PATH], szProcessPath[MAX_PATH];
+
+    /* Compose pop-up title. The dialog title will contain function name to ease the process
+     * locating. Mind that Visual Studio displays window titles on the process list. */
+    _stprintf_s(szTitle, _countof(szTitle), TEXT("%s v%s"), szFunctionName, TEXT(PACKAGE_VERSION));
+
+    /* Get process name. */
+    GetModuleFileName(NULL, szProcessPath, _countof(szProcessPath));
+    LPCTSTR szProcessName = _tcsrchr(szProcessPath, TEXT('\\'));
+    szProcessName = szProcessName ? szProcessName + 1 : szProcessPath;
+
+    /* Compose the pop-up message. */
+    _stprintf_s(
+        szMessage, _countof(szMessage),
+        TEXT("The %s process (PID: %u) has started to execute the %s custom action.\r\n")
+        TEXT("\r\n")
+        TEXT("If you would like to debug the custom action, attach a debugger to this process and set breakpoints before dismissing this dialog.\r\n")
+        TEXT("\r\n")
+        TEXT("If you are not debugging this custom action, you can safely ignore this message."),
+        szProcessName,
+        GetCurrentProcessId(),
+        szFunctionName);
+
+    MessageBox(NULL, szMessage, szTitle, MB_OK);
+}
+
+#define debug_popup(f) _debug_popup(f)
+#else  /* ifdef _DEBUG */
+#define debug_popup(f)
+#endif /* ifdef _DEBUG */
+
+
+/**
+ * Detects if the OpenVPNService service is in use (running or paused) and sets
+ * OPENVPNSERVICE to the service process PID, or its path if it is set to
+ * auto-start, but not running.
+ *
+ * @param hInstall      Handle to the installation provided to the DLL custom action
+ *
+ * @return ERROR_SUCCESS on success; An error code otherwise
+ *         See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa368072.aspx
+ */
+static UINT
+set_openvpnserv_state(_In_ MSIHANDLE hInstall)
+{
+    UINT uiResult;
+
+    /* Get Service Control Manager handle. */
+    SC_HANDLE hSCManager = OpenSCManager(NULL, SERVICES_ACTIVE_DATABASE, SC_MANAGER_CONNECT);
+    if (hSCManager == NULL)
+    {
+        uiResult = GetLastError();
+        msg(M_NONFATAL | M_ERRNO, "%s: OpenSCManager() failed", __FUNCTION__);
+        return uiResult;
+    }
+
+    /* Get OpenVPNService service handle. */
+    SC_HANDLE hService = OpenService(hSCManager, TEXT("OpenVPNService"), SERVICE_QUERY_STATUS | SERVICE_QUERY_CONFIG);
+    if (hService == NULL)
+    {
+        uiResult = GetLastError();
+        if (uiResult == ERROR_SERVICE_DOES_NOT_EXIST)
+        {
+            /* This is not actually an error. */
+            goto cleanup_OpenSCManager;
+        }
+        msg(M_NONFATAL | M_ERRNO, "%s: OpenService(\"OpenVPNService\") failed", __FUNCTION__);
+        goto cleanup_OpenSCManager;
+    }
+
+    /* Query service status. */
+    SERVICE_STATUS_PROCESS ssp;
+    DWORD dwBufSize;
+    if (QueryServiceStatusEx(hService, SC_STATUS_PROCESS_INFO, (LPBYTE)&ssp, sizeof(ssp), &dwBufSize))
+    {
+        switch (ssp.dwCurrentState)
+        {
+            case SERVICE_START_PENDING:
+            case SERVICE_RUNNING:
+            case SERVICE_STOP_PENDING:
+            case SERVICE_PAUSE_PENDING:
+            case SERVICE_PAUSED:
+            case SERVICE_CONTINUE_PENDING:
+            {
+                /* Service is started (kind of). Set OPENVPNSERVICE property to service PID. */
+                TCHAR szPID[10 /*MAXDWORD in decimal*/ + 1 /*terminator*/];
+                _stprintf_s(
+                    szPID, _countof(szPID),
+                    TEXT("%u"),
+                    ssp.dwProcessId);
+
+                uiResult = MsiSetProperty(hInstall, TEXT("OPENVPNSERVICE"), szPID);
+                if (uiResult != ERROR_SUCCESS)
+                {
+                    SetLastError(uiResult); /* MSDN does not mention MsiSetProperty() to set GetLastError(). But we do have an error code. Set last error manually. */
+                    msg(M_NONFATAL | M_ERRNO, "%s: MsiSetProperty(\"OPENVPNSERVICE\") failed", __FUNCTION__);
+                }
+
+                /* We know user is using the service. Skip auto-start setting check. */
+                goto cleanup_OpenService;
+            }
+            break;
+        }
+    }
+    else
+    {
+        uiResult = GetLastError();
+        msg(M_NONFATAL | M_ERRNO, "%s: QueryServiceStatusEx(\"OpenVPNService\") failed", __FUNCTION__);
+    }
+
+    /* Service is not started. Is it set to auto-start? */
+    /* MSDN describes the maximum buffer size for QueryServiceConfig() to be 8kB. */
+    /* This is small enough to fit on stack. */
+    BYTE _buffer_8k[8192];
+    LPQUERY_SERVICE_CONFIG pQsc = (LPQUERY_SERVICE_CONFIG)_buffer_8k;
+    dwBufSize = sizeof(_buffer_8k);
+    if (!QueryServiceConfig(hService, pQsc, dwBufSize, &dwBufSize))
+    {
+        uiResult = GetLastError();
+        msg(M_NONFATAL | M_ERRNO, "%s: QueryServiceStatusEx(\"QueryServiceConfig\") failed", __FUNCTION__);
+        goto cleanup_OpenService;
+    }
+
+    if (pQsc->dwStartType <= SERVICE_AUTO_START)
+    {
+        /* Service is set to auto-start. Set OPENVPNSERVICE property to its path. */
+        uiResult = MsiSetProperty(hInstall, TEXT("OPENVPNSERVICE"), pQsc->lpBinaryPathName);
+        if (uiResult != ERROR_SUCCESS)
+        {
+            SetLastError(uiResult); /* MSDN does not mention MsiSetProperty() to set GetLastError(). But we do have an error code. Set last error manually. */
+            msg(M_NONFATAL | M_ERRNO, "%s: MsiSetProperty(\"OPENVPNSERVICE\") failed", __FUNCTION__);
+            goto cleanup_OpenService;
+        }
+    }
+
+    uiResult = ERROR_SUCCESS;
+
+cleanup_OpenService:
+    CloseServiceHandle(hService);
+cleanup_OpenSCManager:
+    CloseServiceHandle(hSCManager);
+    return uiResult;
+}
+
+
+static UINT
+find_adapters(
+    _In_ MSIHANDLE hInstall,
+    _In_z_ LPCTSTR szzHardwareIDs,
+    _In_z_ LPCTSTR szAdaptersPropertyName,
+    _In_z_ LPCTSTR szActiveAdaptersPropertyName)
+{
+    UINT uiResult;
+
+    /* Get network adapters with given hardware ID. */
+    struct tap_adapter_node *pAdapterList = NULL;
+    uiResult = tap_list_adapters(NULL, szzHardwareIDs, &pAdapterList);
+    if (uiResult != ERROR_SUCCESS)
+    {
+        return uiResult;
+    }
+    else if (pAdapterList == NULL)
+    {
+        /* No adapters - no fun. */
+        return ERROR_SUCCESS;
+    }
+
+    /* Get IPv4/v6 info for all network adapters. Actually, we're interested in link status only: up/down? */
+    PIP_ADAPTER_ADDRESSES pAdapterAdresses = NULL;
+    ULONG ulAdapterAdressesSize = 16*1024;
+    for (size_t iteration = 0; iteration < 2; iteration++)
+    {
+        pAdapterAdresses = (PIP_ADAPTER_ADDRESSES)malloc(ulAdapterAdressesSize);
+        if (pAdapterAdresses == NULL)
+        {
+            msg(M_NONFATAL, "%s: malloc(%u) failed", __FUNCTION__, ulAdapterAdressesSize);
+            uiResult = ERROR_OUTOFMEMORY; goto cleanup_pAdapterList;
+        }
+
+        ULONG ulResult = GetAdaptersAddresses(
+            AF_UNSPEC,
+            GAA_FLAG_SKIP_UNICAST | GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME | GAA_FLAG_INCLUDE_ALL_INTERFACES,
+            NULL,
+            pAdapterAdresses,
+            &ulAdapterAdressesSize);
+
+        if (ulResult == ERROR_SUCCESS)
+        {
+            break;
+        }
+
+        free(pAdapterAdresses);
+        if (ulResult != ERROR_BUFFER_OVERFLOW)
+        {
+            SetLastError(ulResult); /* MSDN does not mention GetAdaptersAddresses() to set GetLastError(). But we do have an error code. Set last error manually. */
+            msg(M_NONFATAL | M_ERRNO, "%s: GetAdaptersAddresses() failed", __FUNCTION__);
+            uiResult = ulResult; goto cleanup_pAdapterList;
+        }
+    }
+
+    /* Count adapters. */
+    size_t adapter_count = 0;
+    for (struct tap_adapter_node *pAdapter = pAdapterList; pAdapter; pAdapter = pAdapter->pNext)
+    {
+        adapter_count++;
+    }
+
+    /* Prepare semicolon delimited list of TAP adapter ID(s) and active TAP adapter ID(s). */
+    LPTSTR
+        szAdapters     = (LPTSTR)malloc(adapter_count * (38 /*GUID*/ + 1 /*separator/terminator*/) * sizeof(TCHAR)),
+        szAdaptersTail = szAdapters;
+    if (szAdapters == NULL)
+    {
+        msg(M_FATAL, "%s: malloc(%u) failed", __FUNCTION__, adapter_count * (38 /*GUID*/ + 1 /*separator/terminator*/) * sizeof(TCHAR));
+        uiResult = ERROR_OUTOFMEMORY; goto cleanup_pAdapterAdresses;
+    }
+
+    LPTSTR
+        szAdaptersActive     = (LPTSTR)malloc(adapter_count * (38 /*GUID*/ + 1 /*separator/terminator*/) * sizeof(TCHAR)),
+        szAdaptersActiveTail = szAdaptersActive;
+    if (szAdaptersActive == NULL)
+    {
+        msg(M_FATAL, "%s: malloc(%u) failed", __FUNCTION__, adapter_count * (38 /*GUID*/ + 1 /*separator/terminator*/) * sizeof(TCHAR));
+        uiResult = ERROR_OUTOFMEMORY; goto cleanup_szAdapters;
+    }
+
+    for (struct tap_adapter_node *pAdapter = pAdapterList; pAdapter; pAdapter = pAdapter->pNext)
+    {
+        /* Convert adapter GUID to UTF-16 string. (LPOLESTR defaults to LPWSTR) */
+        LPOLESTR szAdapterId = NULL;
+        StringFromIID((REFIID)&pAdapter->guid, &szAdapterId);
+
+        /* Append to the list of TAP adapter ID(s). */
+        if (szAdapters < szAdaptersTail)
+        {
+            *(szAdaptersTail++) = TEXT(';');
+        }
+        memcpy(szAdaptersTail, szAdapterId, 38 * sizeof(TCHAR));
+        szAdaptersTail += 38;
+
+        /* If this adapter is active (connected), add it to the list of active TAP adapter ID(s). */
+        for (PIP_ADAPTER_ADDRESSES p = pAdapterAdresses; p; p = p->Next)
+        {
+            OLECHAR szId[38 /*GUID*/ + 1 /*terminator*/];
+            GUID guid;
+            if (MultiByteToWideChar(CP_ACP, MB_PRECOMPOSED, p->AdapterName, -1, szId, _countof(szId)) > 0
+                && SUCCEEDED(IIDFromString(szId, &guid))
+                && memcmp(&guid, &pAdapter->guid, sizeof(GUID)) == 0)
+            {
+                if (p->OperStatus == IfOperStatusUp)
+                {
+                    /* This TAP adapter is active (connected). */
+                    if (szAdaptersActive < szAdaptersActiveTail)
+                    {
+                        *(szAdaptersActiveTail++) = TEXT(';');
+                    }
+                    memcpy(szAdaptersActiveTail, szAdapterId, 38 * sizeof(TCHAR));
+                    szAdaptersActiveTail += 38;
+                }
+                break;
+            }
+        }
+        CoTaskMemFree(szAdapterId);
+    }
+    szAdaptersTail      [0] = 0;
+    szAdaptersActiveTail[0] = 0;
+
+    /* Set Installer properties. */
+    uiResult = MsiSetProperty(hInstall, szAdaptersPropertyName, szAdapters);
+    if (uiResult != ERROR_SUCCESS)
+    {
+        SetLastError(uiResult); /* MSDN does not mention MsiSetProperty() to set GetLastError(). But we do have an error code. Set last error manually. */
+        msg(M_NONFATAL | M_ERRNO, "%s: MsiSetProperty(\"%s\") failed", __FUNCTION__, szAdaptersPropertyName);
+        goto cleanup_szAdaptersActive;
+    }
+    uiResult = MsiSetProperty(hInstall, szActiveAdaptersPropertyName, szAdaptersActive);
+    if (uiResult != ERROR_SUCCESS)
+    {
+        SetLastError(uiResult); /* MSDN does not mention MsiSetProperty() to set GetLastError(). But we do have an error code. Set last error manually. */
+        msg(M_NONFATAL | M_ERRNO, "%s: MsiSetProperty(\"%s\") failed", __FUNCTION__, szActiveAdaptersPropertyName);
+        goto cleanup_szAdaptersActive;
+    }
+
+cleanup_szAdaptersActive:
+    free(szAdaptersActive);
+cleanup_szAdapters:
+    free(szAdapters);
+cleanup_pAdapterAdresses:
+    free(pAdapterAdresses);
+cleanup_pAdapterList:
+    tap_free_adapter_list(pAdapterList);
+    return uiResult;
+}
+
+
+UINT __stdcall
+FindSystemInfo(_In_ MSIHANDLE hInstall)
+{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+
+    debug_popup(TEXT(__FUNCTION__));
+
+    BOOL bIsCoInitialized = SUCCEEDED(CoInitialize(NULL));
+
+    OPENVPNMSICA_SAVE_MSI_SESSION(hInstall);
+
+    set_openvpnserv_state(hInstall);
+    find_adapters(
+        hInstall,
+        TEXT("root\\") TEXT(TAP_WIN_COMPONENT_ID) TEXT("\0") TEXT(TAP_WIN_COMPONENT_ID) TEXT("\0"),
+        TEXT("TAPWINDOWS6ADAPTERS"),
+        TEXT("ACTIVETAPWINDOWS6ADAPTERS"));
+    find_adapters(
+        hInstall,
+        TEXT("Wintun") TEXT("\0"),
+        TEXT("WINTUNADAPTERS"),
+        TEXT("ACTIVEWINTUNADAPTERS"));
+
+    if (bIsCoInitialized)
+    {
+        CoUninitialize();
+    }
+    return ERROR_SUCCESS;
+}
+
+
+UINT __stdcall
+CloseOpenVPNGUI(_In_ MSIHANDLE hInstall)
+{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+    UNREFERENCED_PARAMETER(hInstall); /* This CA is does not interact with MSI session (report errors, access properties, tables, etc.). */
+
+    debug_popup(TEXT(__FUNCTION__));
+
+    /* Find OpenVPN GUI window. */
+    HWND hWnd = FindWindow(TEXT("OpenVPN-GUI"), NULL);
+    if (hWnd)
+    {
+        /* Ask it to close and wait for 100ms. Unfortunately, this will succeed only for recent OpenVPN GUI that do not run elevated. */
+        SendMessage(hWnd, WM_CLOSE, 0, 0);
+        Sleep(100);
+    }
+
+    return ERROR_SUCCESS;
+}
+
+
+UINT __stdcall
+StartOpenVPNGUI(_In_ MSIHANDLE hInstall)
+{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+
+    debug_popup(TEXT(__FUNCTION__));
+
+    UINT uiResult;
+    BOOL bIsCoInitialized = SUCCEEDED(CoInitialize(NULL));
+
+    OPENVPNMSICA_SAVE_MSI_SESSION(hInstall);
+
+    /* Create and populate a MSI record. */
+    MSIHANDLE hRecord = MsiCreateRecord(1);
+    if (!hRecord)
+    {
+        uiResult = ERROR_INVALID_HANDLE;
+        msg(M_NONFATAL, "%s: MsiCreateRecord failed", __FUNCTION__);
+        goto cleanup_CoInitialize;
+    }
+    uiResult = MsiRecordSetString(hRecord, 0, TEXT("\"[#bin.openvpn_gui.exe]\""));
+    if (uiResult != ERROR_SUCCESS)
+    {
+        SetLastError(uiResult); /* MSDN does not mention MsiRecordSetString() to set GetLastError(). But we do have an error code. Set last error manually. */
+        msg(M_NONFATAL | M_ERRNO, "%s: MsiRecordSetString failed", __FUNCTION__);
+        goto cleanup_MsiCreateRecord;
+    }
+
+    /* Format string. */
+    TCHAR szStackBuf[MAX_PATH];
+    DWORD dwPathSize = _countof(szStackBuf);
+    LPTSTR szPath = szStackBuf;
+    uiResult = MsiFormatRecord(hInstall, hRecord, szPath, &dwPathSize);
+    if (uiResult == ERROR_MORE_DATA)
+    {
+        /* Allocate buffer on heap (+1 for terminator), and retry. */
+        szPath = (LPTSTR)malloc((++dwPathSize) * sizeof(TCHAR));
+        if (szPath == NULL)
+        {
+            msg(M_FATAL, "%s: malloc(%u) failed", __FUNCTION__, dwPathSize * sizeof(TCHAR));
+            uiResult = ERROR_OUTOFMEMORY; goto cleanup_MsiCreateRecord;
+        }
+
+        uiResult = MsiFormatRecord(hInstall, hRecord, szPath, &dwPathSize);
+    }
+    if (uiResult != ERROR_SUCCESS)
+    {
+        SetLastError(uiResult); /* MSDN does not mention MsiFormatRecord() to set GetLastError(). But we do have an error code. Set last error manually. */
+        msg(M_NONFATAL | M_ERRNO, "%s: MsiFormatRecord failed", __FUNCTION__);
+        goto cleanup_malloc_szPath;
+    }
+
+    /* Launch the OpenVPN GUI. */
+    SHELLEXECUTEINFO sei = {
+        .cbSize = sizeof(SHELLEXECUTEINFO),
+        .fMask  = SEE_MASK_FLAG_NO_UI, /* Don't show error UI, we'll display it. */
+        .lpFile = szPath,
+        .nShow  = SW_SHOWNORMAL
+    };
+    if (!ShellExecuteEx(&sei))
+    {
+        uiResult = GetLastError();
+        msg(M_NONFATAL | M_ERRNO, "%s: ShellExecuteEx(%s) failed", __FUNCTION__, szPath);
+        goto cleanup_malloc_szPath;
+    }
+
+    uiResult = ERROR_SUCCESS;
+
+cleanup_malloc_szPath:
+    if (szPath != szStackBuf)
+    {
+        free(szPath);
+    }
+cleanup_MsiCreateRecord:
+    MsiCloseHandle(hRecord);
+cleanup_CoInitialize:
+    if (bIsCoInitialized)
+    {
+        CoUninitialize();
+    }
+    return uiResult;
+}
+
+
+/**
+ * Schedules adapter creation.
+ *
+ * When the rollback is enabled, the adapter deletition is scheduled on rollback.
+ *
+ * @param seq           The argument sequence to pass to InstallTUNTAPAdapters custom action
+ *
+ * @param seqRollback   The argument sequence to pass to InstallTUNTAPAdaptersRollback custom
+ *                      action. NULL when rollback is disabled.
+ *
+ * @param szDisplayName  Adapter display name
+ *
+ * @param szHardwareId  Adapter hardware ID
+ *
+ * @param iTicks        Pointer to an integer that represents amount of work (on progress
+ *                      indicator) the InstallTUNTAPAdapters will take. This function increments it
+ *                      by MSICA_ADAPTER_TICK_SIZE for each adapter to create.
+ *
+ * @return ERROR_SUCCESS on success; An error code otherwise
+ */
+static DWORD
+schedule_adapter_create(
+    _Inout_ struct msica_arg_seq *seq,
+    _Inout_opt_ struct msica_arg_seq *seqRollback,
+    _In_z_ LPCTSTR szDisplayName,
+    _In_z_ LPCTSTR szHardwareId,
+    _Inout_ int *iTicks)
+{
+    /* Get existing network adapters. */
+    struct tap_adapter_node *pAdapterList = NULL;
+    DWORD dwResult = tap_list_adapters(NULL, NULL, &pAdapterList);
+    if (dwResult != ERROR_SUCCESS)
+    {
+        return dwResult;
+    }
+
+    /* Does adapter exist? */
+    for (struct tap_adapter_node *pAdapterOther = pAdapterList;; pAdapterOther = pAdapterOther->pNext)
+    {
+        if (pAdapterOther == NULL)
+        {
+            /* No adapter with a same name found. */
+            TCHAR szArgument[10 /*create=""|deleteN=""*/ + MAX_PATH /*szDisplayName*/ + 1 /*|*/ + MAX_PATH /*szHardwareId*/ + 1 /*terminator*/];
+
+            /* InstallTUNTAPAdapters will create the adapter. */
+            _stprintf_s(
+                szArgument, _countof(szArgument),
+                TEXT("create=\"%.*s|%.*s\""),
+                MAX_PATH, szDisplayName,
+                MAX_PATH, szHardwareId);
+            msica_arg_seq_add_tail(seq, szArgument);
+
+            if (seqRollback)
+            {
+                /* InstallTUNTAPAdaptersRollback will delete the adapter. */
+                _stprintf_s(
+                    szArgument, _countof(szArgument),
+                    TEXT("deleteN=\"%.*s\""),
+                    MAX_PATH, szDisplayName);
+                msica_arg_seq_add_head(seqRollback, szArgument);
+            }
+
+            *iTicks += MSICA_ADAPTER_TICK_SIZE;
+            break;
+        }
+        else if (_tcsicmp(szDisplayName, pAdapterOther->szName) == 0)
+        {
+            /* Adapter with a same name found. */
+            for (LPCTSTR hwid = pAdapterOther->szzHardwareIDs;; hwid += _tcslen(hwid) + 1)
+            {
+                if (hwid[0] == 0)
+                {
+                    /* This adapter has a different hardware ID. */
+                    msg(M_NONFATAL, "%s: Adapter with name \"%" PRIsLPTSTR "\" already exists", __FUNCTION__, pAdapterOther->szName);
+                    dwResult = ERROR_ALREADY_EXISTS;
+                    goto cleanup_pAdapterList;
+                }
+                else if (_tcsicmp(hwid, szHardwareId) == 0)
+                {
+                    /* This is an adapter with the requested hardware ID. We already have what we want! */
+                    break;
+                }
+            }
+            break; /* Adapter names are unique. There should be no other adapter with this name. */
+        }
+    }
+
+cleanup_pAdapterList:
+    tap_free_adapter_list(pAdapterList);
+    return dwResult;
+}
+
+
+/**
+ * Schedules adapter deletion.
+ *
+ * When the rollback is enabled, the adapter deletition is scheduled as: disable in
+ * UninstallTUNTAPAdapters, enable on rollback, delete on commit.
+ *
+ * When rollback is disabled, the adapter deletition is scheduled as delete in
+ * UninstallTUNTAPAdapters.
+ *
+ * @param seq           The argument sequence to pass to UninstallTUNTAPAdapters custom action
+ *
+ * @param seqCommit     The argument sequence to pass to UninstallTUNTAPAdaptersCommit custom
+ *                      action. NULL when rollback is disabled.
+ *
+ * @param seqRollback   The argument sequence to pass to UninstallTUNTAPAdaptersRollback custom
+ *                      action. NULL when rollback is disabled.
+ *
+ * @param szDisplayName  Adapter display name
+ *
+ * @param szzHardwareIDs  String of strings with acceptable adapter hardware IDs
+ *
+ * @param iTicks        Pointer to an integer that represents amount of work (on progress
+ *                      indicator) the UninstallTUNTAPAdapters will take. This function increments
+ *                      it by MSICA_ADAPTER_TICK_SIZE for each adapter to delete.
+ *
+ * @return ERROR_SUCCESS on success; An error code otherwise
+ */
+static DWORD
+schedule_adapter_delete(
+    _Inout_ struct msica_arg_seq *seq,
+    _Inout_opt_ struct msica_arg_seq *seqCommit,
+    _Inout_opt_ struct msica_arg_seq *seqRollback,
+    _In_z_ LPCTSTR szDisplayName,
+    _In_z_ LPCTSTR szzHardwareIDs,
+    _Inout_ int *iTicks)
+{
+    /* Get adapters with given hardware ID. */
+    struct tap_adapter_node *pAdapterList = NULL;
+    DWORD dwResult = tap_list_adapters(NULL, szzHardwareIDs, &pAdapterList);
+    if (dwResult != ERROR_SUCCESS)
+    {
+        return dwResult;
+    }
+
+    /* Does adapter exist? */
+    for (struct tap_adapter_node *pAdapter = pAdapterList; pAdapter != NULL; pAdapter = pAdapter->pNext)
+    {
+        if (_tcsicmp(szDisplayName, pAdapter->szName) == 0)
+        {
+            /* Adapter found. */
+            TCHAR szArgument[8 /*disable=|enable=|delete=*/ + 38 /*{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}*/ + 1 /*terminator*/];
+            if (seqCommit && seqRollback)
+            {
+                /* UninstallTUNTAPAdapters will disable the adapter. */
+                _stprintf_s(
+                    szArgument, _countof(szArgument),
+                    TEXT("disable=") TEXT(PRIXGUID),
+                    PRIGUID_PARAM(pAdapter->guid));
+                msica_arg_seq_add_tail(seq, szArgument);
+
+                /* UninstallTUNTAPAdaptersRollback will re-enable the adapter. */
+                _stprintf_s(
+                    szArgument, _countof(szArgument),
+                    TEXT("enable=") TEXT(PRIXGUID),
+                    PRIGUID_PARAM(pAdapter->guid));
+                msica_arg_seq_add_head(seqRollback, szArgument);
+
+                /* UninstallTUNTAPAdaptersCommit will delete the adapter. */
+                _stprintf_s(
+                    szArgument, _countof(szArgument),
+                    TEXT("delete=") TEXT(PRIXGUID),
+                    PRIGUID_PARAM(pAdapter->guid));
+                msica_arg_seq_add_tail(seqCommit, szArgument);
+            }
+            else
+            {
+                /* UninstallTUNTAPAdapters will delete the adapter. */
+                _stprintf_s(
+                    szArgument, _countof(szArgument),
+                    TEXT("delete=") TEXT(PRIXGUID),
+                    PRIGUID_PARAM(pAdapter->guid));
+                msica_arg_seq_add_tail(seq, szArgument);
+            }
+
+            iTicks += MSICA_ADAPTER_TICK_SIZE;
+            break; /* Adapter names are unique. There should be no other adapter with this name. */
+        }
+    }
+
+    tap_free_adapter_list(pAdapterList);
+    return dwResult;
+}
+
+
+UINT __stdcall
+EvaluateTUNTAPAdapters(_In_ MSIHANDLE hInstall)
+{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+
+    debug_popup(TEXT(__FUNCTION__));
+
+    UINT uiResult;
+    BOOL bIsCoInitialized = SUCCEEDED(CoInitialize(NULL));
+
+    OPENVPNMSICA_SAVE_MSI_SESSION(hInstall);
+
+    struct msica_arg_seq
+        seqInstall,
+        seqInstallCommit,
+        seqInstallRollback,
+        seqUninstall,
+        seqUninstallCommit,
+        seqUninstallRollback;
+    msica_arg_seq_init(&seqInstall);
+    msica_arg_seq_init(&seqInstallCommit);
+    msica_arg_seq_init(&seqInstallRollback);
+    msica_arg_seq_init(&seqUninstall);
+    msica_arg_seq_init(&seqUninstallCommit);
+    msica_arg_seq_init(&seqUninstallRollback);
+
+    /* Check rollback state. */
+    bool bRollbackEnabled = MsiEvaluateCondition(hInstall, TEXT("RollbackDisabled")) != MSICONDITION_TRUE;
+
+    /* Open MSI database. */
+    MSIHANDLE hDatabase = MsiGetActiveDatabase(hInstall);
+    if (hDatabase == 0)
+    {
+        msg(M_NONFATAL, "%s: MsiGetActiveDatabase failed", __FUNCTION__);
+        uiResult = ERROR_INVALID_HANDLE;
+        goto cleanup_exec_seq;
+    }
+
+    /* Check if TUNTAPAdapter table exists. If it doesn't exist, there's nothing to do. */
+    switch (MsiDatabaseIsTablePersistent(hDatabase, TEXT("TUNTAPAdapter")))
+    {
+        case MSICONDITION_FALSE:
+        case MSICONDITION_TRUE: break;
+
+        default:
+            uiResult = ERROR_SUCCESS;
+            goto cleanup_hDatabase;
+    }
+
+    /* Prepare a query to get a list/view of adapters. */
+    MSIHANDLE hViewST = 0;
+    LPCTSTR szQuery = TEXT("SELECT `Adapter`,`DisplayName`,`Condition`,`Component_`,`HardwareId` FROM `TUNTAPAdapter`");
+    uiResult = MsiDatabaseOpenView(hDatabase, szQuery, &hViewST);
+    if (uiResult != ERROR_SUCCESS)
+    {
+        SetLastError(uiResult); /* MSDN does not mention MsiDatabaseOpenView() to set GetLastError(). But we do have an error code. Set last error manually. */
+        msg(M_NONFATAL | M_ERRNO, "%s: MsiDatabaseOpenView(\"%" PRIsLPTSTR "\") failed", __FUNCTION__, szQuery);
+        goto cleanup_hDatabase;
+    }
+
+    /* Execute query! */
+    uiResult = MsiViewExecute(hViewST, 0);
+    if (uiResult != ERROR_SUCCESS)
+    {
+        SetLastError(uiResult); /* MSDN does not mention MsiViewExecute() to set GetLastError(). But we do have an error code. Set last error manually. */
+        msg(M_NONFATAL | M_ERRNO, "%s: MsiViewExecute(\"%" PRIsLPTSTR "\") failed", __FUNCTION__, szQuery);
+        goto cleanup_hViewST;
+    }
+
+    /* Create a record to report progress with. */
+    MSIHANDLE hRecordProg = MsiCreateRecord(2);
+    if (!hRecordProg)
+    {
+        uiResult = ERROR_INVALID_HANDLE;
+        msg(M_NONFATAL, "%s: MsiCreateRecord failed", __FUNCTION__);
+        goto cleanup_hViewST_close;
+    }
+
+    for (;; )
+    {
+        /* Fetch one record from the view. */
+        MSIHANDLE hRecord = 0;
+        uiResult = MsiViewFetch(hViewST, &hRecord);
+        if (uiResult == ERROR_NO_MORE_ITEMS)
+        {
+            uiResult = ERROR_SUCCESS;
+            break;
+        }
+        else if (uiResult != ERROR_SUCCESS)
+        {
+            SetLastError(uiResult); /* MSDN does not mention MsiViewFetch() to set GetLastError(). But we do have an error code. Set last error manually. */
+            msg(M_NONFATAL | M_ERRNO, "%s: MsiViewFetch failed", __FUNCTION__);
+            goto cleanup_hRecordProg;
+        }
+
+        INSTALLSTATE iInstalled, iAction;
+        {
+            /* Read adapter component ID (`Component_` is field #4). */
+            LPTSTR szValue = NULL;
+            uiResult = msi_get_record_string(hRecord, 4, &szValue);
+            if (uiResult != ERROR_SUCCESS)
+            {
+                goto cleanup_hRecord;
+            }
+
+            /* Get the component state. */
+            uiResult = MsiGetComponentState(hInstall, szValue, &iInstalled, &iAction);
+            if (uiResult != ERROR_SUCCESS)
+            {
+                SetLastError(uiResult); /* MSDN does not mention MsiGetComponentState() to set GetLastError(). But we do have an error code. Set last error manually. */
+                msg(M_NONFATAL | M_ERRNO, "%s: MsiGetComponentState(\"%" PRIsLPTSTR "\") failed", __FUNCTION__, szValue);
+                free(szValue);
+                goto cleanup_hRecord;
+            }
+            free(szValue);
+        }
+
+        /* Get adapter display name (`DisplayName` is field #2). */
+        LPTSTR szDisplayName = NULL;
+        uiResult = msi_format_field(hInstall, hRecord, 2, &szDisplayName);
+        if (uiResult != ERROR_SUCCESS)
+        {
+            goto cleanup_hRecord;
+        }
+        /* `DisplayName` field type is [Filename](https://docs.microsoft.com/en-us/windows/win32/msi/filename), which is either "8.3|long name" or "8.3". */
+        LPTSTR szDisplayNameEx = _tcschr(szDisplayName, TEXT('|'));
+        szDisplayNameEx = szDisplayNameEx != NULL ? szDisplayNameEx + 1 : szDisplayName;
+
+        /* Get adapter hardware ID (`HardwareId` is field #5). */
+        TCHAR szzHardwareIDs[0x100] = { 0 };
+        {
+            LPTSTR szHwId = NULL;
+            uiResult = msi_get_record_string(hRecord, 5, &szHwId);
+            if (uiResult != ERROR_SUCCESS)
+            {
+                goto cleanup_szDisplayName;
+            }
+            memcpy_s(szzHardwareIDs, sizeof(szzHardwareIDs) - 2*sizeof(TCHAR) /*requires double zero termination*/, szHwId, _tcslen(szHwId)*sizeof(TCHAR));
+            free(szHwId);
+        }
+
+        if (iAction > INSTALLSTATE_BROKEN)
+        {
+            int iTicks = 0;
+
+            if (iAction >= INSTALLSTATE_LOCAL)
+            {
+                /* Read and evaluate adapter condition (`Condition` is field #3). */
+                LPTSTR szValue = NULL;
+                uiResult = msi_get_record_string(hRecord, 3, &szValue);
+                if (uiResult != ERROR_SUCCESS)
+                {
+                    goto cleanup_szDisplayName;
+                }
+#ifdef __GNUC__
+/*
+ * warning: enumeration value ‘MSICONDITION_TRUE’ not handled in switch
+ * warning: enumeration value ‘MSICONDITION_NONE’ not handled in switch
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wswitch"
+#endif
+                switch (MsiEvaluateCondition(hInstall, szValue))
+                {
+                    case MSICONDITION_FALSE:
+                        free(szValue);
+                        goto cleanup_szDisplayName;
+
+                    case MSICONDITION_ERROR:
+                        uiResult = ERROR_INVALID_FIELD;
+                        msg(M_NONFATAL | M_ERRNO, "%s: MsiEvaluateCondition(\"%" PRIsLPTSTR "\") failed", __FUNCTION__, szValue);
+                        free(szValue);
+                        goto cleanup_szDisplayName;
+                }
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
+                free(szValue);
+
+                /* Component is or should be installed. Schedule adapter creation. */
+                if (schedule_adapter_create(
+                        &seqInstall,
+                        bRollbackEnabled ? &seqInstallRollback : NULL,
+                        szDisplayNameEx,
+                        szzHardwareIDs,
+                        &iTicks) != ERROR_SUCCESS)
+                {
+                    uiResult = ERROR_INSTALL_FAILED;
+                    goto cleanup_szDisplayName;
+                }
+            }
+            else
+            {
+                /* Component is installed, but should be degraded to advertised/removed. Schedule adapter deletition.
+                 *
+                 * Note: On adapter removal (product is being uninstalled), we tolerate dwResult error.
+                 * Better a partial uninstallation than no uninstallation at all.
+                 */
+                schedule_adapter_delete(
+                    &seqUninstall,
+                    bRollbackEnabled ? &seqUninstallCommit : NULL,
+                    bRollbackEnabled ? &seqUninstallRollback : NULL,
+                    szDisplayNameEx,
+                    szzHardwareIDs,
+                    &iTicks);
+            }
+
+            /* Arrange the amount of tick space to add to the progress indicator.
+             * Do this within the loop to poll for user cancellation. */
+            MsiRecordSetInteger(hRecordProg, 1, 3 /* OP3 = Add ticks to the expected total number of progress of the progress bar */);
+            MsiRecordSetInteger(hRecordProg, 2, iTicks);
+            if (MsiProcessMessage(hInstall, INSTALLMESSAGE_PROGRESS, hRecordProg) == IDCANCEL)
+            {
+                uiResult = ERROR_INSTALL_USEREXIT;
+                goto cleanup_szDisplayName;
+            }
+        }
+
+cleanup_szDisplayName:
+        free(szDisplayName);
+cleanup_hRecord:
+        MsiCloseHandle(hRecord);
+        if (uiResult != ERROR_SUCCESS)
+        {
+            goto cleanup_hRecordProg;
+        }
+    }
+
+    /* Store deferred custom action parameters. */
+    if ((uiResult = setup_sequence(hInstall, TEXT("InstallTUNTAPAdapters"          ), &seqInstall          )) != ERROR_SUCCESS
+        || (uiResult = setup_sequence(hInstall, TEXT("InstallTUNTAPAdaptersCommit"    ), &seqInstallCommit    )) != ERROR_SUCCESS
+        || (uiResult = setup_sequence(hInstall, TEXT("InstallTUNTAPAdaptersRollback"  ), &seqInstallRollback  )) != ERROR_SUCCESS
+        || (uiResult = setup_sequence(hInstall, TEXT("UninstallTUNTAPAdapters"        ), &seqUninstall        )) != ERROR_SUCCESS
+        || (uiResult = setup_sequence(hInstall, TEXT("UninstallTUNTAPAdaptersCommit"  ), &seqUninstallCommit  )) != ERROR_SUCCESS
+        || (uiResult = setup_sequence(hInstall, TEXT("UninstallTUNTAPAdaptersRollback"), &seqUninstallRollback)) != ERROR_SUCCESS)
+    {
+        goto cleanup_hRecordProg;
+    }
+
+    uiResult = ERROR_SUCCESS;
+
+cleanup_hRecordProg:
+    MsiCloseHandle(hRecordProg);
+cleanup_hViewST_close:
+    MsiViewClose(hViewST);
+cleanup_hViewST:
+    MsiCloseHandle(hViewST);
+cleanup_hDatabase:
+    MsiCloseHandle(hDatabase);
+cleanup_exec_seq:
+    msica_arg_seq_free(&seqInstall);
+    msica_arg_seq_free(&seqInstallCommit);
+    msica_arg_seq_free(&seqInstallRollback);
+    msica_arg_seq_free(&seqUninstall);
+    msica_arg_seq_free(&seqUninstallCommit);
+    msica_arg_seq_free(&seqUninstallRollback);
+    if (bIsCoInitialized)
+    {
+        CoUninitialize();
+    }
+    return uiResult;
+}
+
+
+/**
+ * Parses string encoded GUID.
+ *
+ * @param szArg         Zero terminated string where the GUID string starts
+ *
+ * @param guid          Pointer to GUID that receives parsed value
+ *
+ * @return TRUE on success; FALSE otherwise
+ */
+static BOOL
+parse_guid(
+    _In_z_ LPCWSTR szArg,
+    _Out_ GUID *guid)
+{
+    if (swscanf_s(szArg, _L(PRIXGUID), PRIGUID_PARAM_REF(*guid)) != 11)
+    {
+        msg(M_NONFATAL | M_ERRNO, "%s: swscanf_s(\"%ls\") failed", __FUNCTION__, szArg);
+        return FALSE;
+    }
+    return TRUE;
+}
+
+
+UINT __stdcall
+ProcessDeferredAction(_In_ MSIHANDLE hInstall)
+{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+
+    debug_popup(TEXT(__FUNCTION__));
+
+    UINT uiResult;
+    BOOL bIsCoInitialized = SUCCEEDED(CoInitialize(NULL));
+
+    OPENVPNMSICA_SAVE_MSI_SESSION(hInstall);
+
+    BOOL bIsCleanup = MsiGetMode(hInstall, MSIRUNMODE_COMMIT) || MsiGetMode(hInstall, MSIRUNMODE_ROLLBACK);
+
+    /* Get sequence arguments. Always Unicode as CommandLineToArgvW() is available as Unicode-only. */
+    LPWSTR szSequence = NULL;
+    uiResult = msi_get_string(hInstall, L"CustomActionData", &szSequence);
+    if (uiResult != ERROR_SUCCESS)
+    {
+        goto cleanup_CoInitialize;
+    }
+    int nArgs;
+    LPWSTR *szArg = CommandLineToArgvW(szSequence, &nArgs);
+    if (szArg == NULL)
+    {
+        uiResult = GetLastError();
+        msg(M_NONFATAL | M_ERRNO, "%s: CommandLineToArgvW(\"%ls\") failed", __FUNCTION__, szSequence);
+        goto cleanup_szSequence;
+    }
+
+    /* Tell the installer to use explicit progress messages. */
+    MSIHANDLE hRecordProg = MsiCreateRecord(3);
+    MsiRecordSetInteger(hRecordProg, 1, 1);
+    MsiRecordSetInteger(hRecordProg, 2, 1);
+    MsiRecordSetInteger(hRecordProg, 3, 0);
+    MsiProcessMessage(hInstall, INSTALLMESSAGE_PROGRESS, hRecordProg);
+
+    /* Prepare hRecordProg for progress messages. */
+    MsiRecordSetInteger(hRecordProg, 1, 2);
+    MsiRecordSetInteger(hRecordProg, 3, 0);
+
+    BOOL bRebootRequired = FALSE;
+
+    for (int i = 1 /*CommandLineToArgvW injects msiexec.exe as szArg[0]*/; i < nArgs; ++i)
+    {
+        DWORD dwResult = ERROR_SUCCESS;
+
+        if (wcsncmp(szArg[i], L"create=", 7) == 0)
+        {
+            /* Create an adapter with a given name and hardware ID. */
+            LPWSTR szName = szArg[i] + 7;
+            LPWSTR szHardwareId = wcschr(szName, L'|');
+            if (szHardwareId == NULL)
+            {
+                goto invalid_argument;
+            }
+            szHardwareId[0] = 0;
+            ++szHardwareId;
+
+            {
+                /* Report the name of the adapter to installer. */
+                MSIHANDLE hRecord = MsiCreateRecord(4);
+                MsiRecordSetString(hRecord, 1, TEXT("Creating adapter"));
+                MsiRecordSetString(hRecord, 2, szName);
+                MsiRecordSetString(hRecord, 3, szHardwareId);
+                int iResult = MsiProcessMessage(hInstall, INSTALLMESSAGE_ACTIONDATA, hRecord);
+                MsiCloseHandle(hRecord);
+                if (iResult == IDCANCEL)
+                {
+                    uiResult = ERROR_INSTALL_USEREXIT;
+                    goto cleanup;
+                }
+            }
+
+            GUID guidAdapter;
+            dwResult = tap_create_adapter(NULL, NULL, szHardwareId, &bRebootRequired, &guidAdapter);
+            if (dwResult == ERROR_SUCCESS)
+            {
+                /* Set adapter name. */
+                dwResult = tap_set_adapter_name(&guidAdapter, szName);
+                if (dwResult != ERROR_SUCCESS)
+                {
+                    tap_delete_adapter(NULL, &guidAdapter, &bRebootRequired);
+                }
+            }
+        }
+        else if (wcsncmp(szArg[i], L"deleteN=", 8) == 0)
+        {
+            /* Delete the adapter by name. */
+            LPCWSTR szName = szArg[i] + 8;
+
+            {
+                /* Report the name of the adapter to installer. */
+                MSIHANDLE hRecord = MsiCreateRecord(3);
+                MsiRecordSetString(hRecord, 1, TEXT("Deleting adapter"));
+                MsiRecordSetString(hRecord, 2, szName);
+                int iResult = MsiProcessMessage(hInstall, INSTALLMESSAGE_ACTIONDATA, hRecord);
+                MsiCloseHandle(hRecord);
+                if (iResult == IDCANCEL)
+                {
+                    uiResult = ERROR_INSTALL_USEREXIT;
+                    goto cleanup;
+                }
+            }
+
+            /* Get existing adapters. */
+            struct tap_adapter_node *pAdapterList = NULL;
+            dwResult = tap_list_adapters(NULL, NULL, &pAdapterList);
+            if (dwResult == ERROR_SUCCESS)
+            {
+                /* Does the adapter exist? */
+                for (struct tap_adapter_node *pAdapter = pAdapterList; pAdapter != NULL; pAdapter = pAdapter->pNext)
+                {
+                    if (_tcsicmp(szName, pAdapter->szName) == 0)
+                    {
+                        /* Adapter found. */
+                        dwResult = tap_delete_adapter(NULL, &pAdapter->guid, &bRebootRequired);
+                        break;
+                    }
+                }
+
+                tap_free_adapter_list(pAdapterList);
+            }
+        }
+        else if (wcsncmp(szArg[i], L"delete=", 7) == 0)
+        {
+            /* Delete the adapter by GUID. */
+            GUID guid;
+            if (!parse_guid(szArg[i] + 7, &guid))
+            {
+                goto invalid_argument;
+            }
+            dwResult = tap_delete_adapter(NULL, &guid, &bRebootRequired);
+        }
+        else if (wcsncmp(szArg[i], L"enable=", 7) == 0)
+        {
+            /* Enable the adapter. */
+            GUID guid;
+            if (!parse_guid(szArg[i] + 7, &guid))
+            {
+                goto invalid_argument;
+            }
+            dwResult = tap_enable_adapter(NULL, &guid, TRUE, &bRebootRequired);
+        }
+        else if (wcsncmp(szArg[i], L"disable=", 8) == 0)
+        {
+            /* Disable the adapter. */
+            GUID guid;
+            if (!parse_guid(szArg[i] + 8, &guid))
+            {
+                goto invalid_argument;
+            }
+            dwResult = tap_enable_adapter(NULL, &guid, FALSE, &bRebootRequired);
+        }
+        else
+        {
+            goto invalid_argument;
+        }
+
+        if (dwResult != ERROR_SUCCESS && !bIsCleanup /* Ignore errors in case of commit/rollback to do as much work as possible. */)
+        {
+            uiResult = ERROR_INSTALL_FAILURE;
+            goto cleanup;
+        }
+
+        /* Report progress and check for user cancellation. */
+        MsiRecordSetInteger(hRecordProg, 2, MSICA_ADAPTER_TICK_SIZE);
+        if (MsiProcessMessage(hInstall, INSTALLMESSAGE_PROGRESS, hRecordProg) == IDCANCEL)
+        {
+            dwResult = ERROR_INSTALL_USEREXIT;
+            goto cleanup;
+        }
+
+        continue;
+
+invalid_argument:
+        msg(M_NONFATAL, "%s: Ignoring invalid argument: %ls", __FUNCTION__, szArg[i]);
+    }
+
+cleanup:
+    if (bRebootRequired)
+    {
+        MsiSetMode(hInstall, MSIRUNMODE_REBOOTATEND, TRUE);
+    }
+    MsiCloseHandle(hRecordProg);
+    LocalFree(szArg);
+cleanup_szSequence:
+    free(szSequence);
+cleanup_CoInitialize:
+    if (bIsCoInitialized)
+    {
+        CoUninitialize();
+    }
+    return uiResult;
+}