@@ -37,7 +37,8 @@ typedef enum {

     msg_flush_neighbors,

     msg_add_block_dns,

     msg_del_block_dns,

-    msg_register_dns

+    msg_register_dns,

+    msg_enable_dhcp,

 } message_type_t;

 typedef struct {

@@ -111,4 +112,9 @@ typedef struct {

     interface_t iface;

 } block_dns_message_t;

+typedef struct {

+    message_header_t header;

+    interface_t iface;

+} enable_dhcp_message_t;

+

 #endif /* ifndef OPENVPN_MSG_H_ */

@@ -5203,6 +5203,49 @@ netsh_enable_dhcp(const struct tuntap_options *to,

     argv_reset(&argv);

 }

+/* Enable dhcp on tap adapter using iservice */

+static bool

+service_enable_dhcp(const struct tuntap *tt)

+{

+    DWORD len;

+    bool ret = false;

+    ack_message_t ack;

+    struct gc_arena gc = gc_new();

+    HANDLE pipe = tt->options.msg_channel;

+

+    enable_dhcp_message_t dhcp = {

+        .header = {

+            msg_enable_dhcp,

+            sizeof(enable_dhcp_message_t),

+            0

+        },

+        .iface = { .index = tt->adapter_index, .name = "" }

+    };

+

+    if (!WriteFile(pipe, &dhcp, sizeof(dhcp), &len, NULL)

+        || !ReadFile(pipe, &ack, sizeof(ack), &len, NULL))

+    {

+        msg(M_WARN, "Enable_dhcp: could not talk to service: %s [%lu]",

+            strerror_win32(GetLastError(), &gc), GetLastError());

+        goto out;

+    }

+

+    if (ack.error_number != NO_ERROR)

+    {

+        msg(M_NONFATAL, "TUN: enabling dhcp using service failed: %s [status=%u if_index=%d]",

+            strerror_win32(ack.error_number, &gc), ack.error_number, dhcp.iface.index);

+    }

+    else

+    {

+        msg(M_INFO, "DHCP enabled on interface %d using service", dhcp.iface.index);

+        ret = true;

+    }

+

+out:

+    gc_free(&gc);

+    return ret;

+}

+

 /*

  * Return a TAP name for netsh commands.

  */

@@ -5683,7 +5726,15 @@ open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun

              */

             if (dhcp_status(tt->adapter_index) == DHCP_STATUS_DISABLED)

             {

-                netsh_enable_dhcp(&tt->options, tt->actual_name);

+                /* try using the service if available, else directly execute netsh */

+                if (tt->options.msg_channel)

+                {

+                    service_enable_dhcp(tt);

+                }

+                else

+                {

+                    netsh_enable_dhcp(&tt->options, tt->actual_name);

+                }

             }

             dhcp_masq = true;

             dhcp_masq_post = true;

@@ -1164,6 +1164,45 @@ out:

     return err;

 }

+static DWORD

+HandleEnableDHCPMessage(const enable_dhcp_message_t *dhcp)

+{

+    DWORD err = 0;

+    DWORD timeout = 5000; /* in milli seconds */

+    wchar_t argv0[MAX_PATH];

+

+    /* Path of netsh */

+    swprintf(argv0, _countof(argv0), L"%s\\%s", get_win_sys_path(), L"netsh.exe");

+    argv0[_countof(argv0) - 1] = L'\0';

+

+    /* cmd template:

+     * netsh interface ipv4 set address name=$if_index source=dhcp

+     */

+    const wchar_t *fmt = L"netsh interface ipv4 set address name=\"%d\" source=dhcp";

+

+    /* max cmdline length in wchars -- include room for if index:

+     * 10 chars for 32 bit int in decimal and +1 for NUL

+     */

+    size_t ncmdline = wcslen(fmt) + 10 + 1;

+    wchar_t *cmdline = malloc(ncmdline*sizeof(wchar_t));

+    if (!cmdline)

+    {

+        err = ERROR_OUTOFMEMORY;

+        return err;

+    }

+

+    openvpn_sntprintf(cmdline, ncmdline, fmt, dhcp->iface.index);

+

+    err = ExecCommand(argv0, cmdline, timeout);

+

+    /* Note: This could fail if dhcp is already enabled, so the caller

+     * may not want to treat errors as FATAL.

+     */

+

+    free(cmdline);

+    return err;

+}

+

 static VOID

 HandleMessage(HANDLE pipe, DWORD bytes, DWORD count, LPHANDLE events, undo_lists_t *lists)

 {

@@ -1175,6 +1214,7 @@ HandleMessage(HANDLE pipe, DWORD bytes, DWORD count, LPHANDLE events, undo_lists

         flush_neighbors_message_t flush_neighbors;

         block_dns_message_t block_dns;

         dns_cfg_message_t dns;

+        enable_dhcp_message_t dhcp;

     } msg;

     ack_message_t ack = {

         .header = {

@@ -1235,6 +1275,13 @@ HandleMessage(HANDLE pipe, DWORD bytes, DWORD count, LPHANDLE events, undo_lists

             ack.error_number = HandleDNSConfigMessage(&msg.dns, lists);

             break;

+        case msg_enable_dhcp:

+            if (msg.header.size == sizeof(msg.dhcp))

+            {

+                ack.error_number = HandleEnableDHCPMessage(&msg.dhcp);

+            }

+            break;

+

         default:

             ack.error_number = ERROR_MESSAGE_TYPE;

             MsgToEventLog(MSG_FLAGS_ERROR, TEXT("Unknown message type %d"), msg.header.type);