try extracting dns bind addr from INI on windows

include/tuntap.h

@@ -152,7 +152,8 @@ extern "C"
     int flags; /* ifr.ifr_flags on Unix */
     char if_name[IF_NAMESIZE];
 #if defined(Windows)
-    int idx; /* needed to set ipv6 address */
+    int idx;        /* needed to set ipv6 address */
+    DWORD bindaddr; /* set DNS client address */
 #endif
 #if defined(FreeBSD)
     int mode;

llarp/ev/ev.h

@@ -207,6 +207,9 @@ struct llarp_tun_io
 {
   // TODO: more info?
   char ifaddr[128];
+#ifdef _WIN32
+  uint32_t bindaddr;
+#endif
   int netmask;
   char ifname[IFNAMSIZ + 1];
 

llarp/ev/ev_win32.cpp

@@ -58,6 +58,7 @@ win32_tun_io::setup()
     llarp::LogWarn("failed to put interface up: ", ebuf);
     return false;
   }
+  tunif->bindaddr = t->bindaddr;
 
   if(tuntap_set_ip(tunif, t->ifaddr, t->ifaddr, t->netmask) == -1)
   {

llarp/handlers/exit.cpp

@@ -37,10 +37,17 @@ namespace llarp
         , m_Resolver(std::make_shared< dns::Proxy >(
               r->netloop(), r->logic(), r->netloop(), r->logic(), this))
         , m_Name(name)
+#ifdef _WIN32
+        , m_Tun
+    {
+      {0}, 0, 0, {0}, nullptr, nullptr, nullptr,
+#else
         , m_Tun{{0},     0,       {0},     nullptr, nullptr, nullptr,
-                nullptr, nullptr, nullptr, nullptr, nullptr}
-        , m_LocalResolverAddr("127.0.0.1", 53)
-        , m_InetToNetwork(name + "_exit_rx", r->netloop(), r->netloop())
+#endif
+          nullptr, nullptr, nullptr, nullptr, nullptr
+    }
+    , m_LocalResolverAddr("127.0.0.1", 53),
+        m_InetToNetwork(name + "_exit_rx", r->netloop(), r->netloop())
 
     {
       m_Tun.user      = this;

llarp/handlers/tun.cpp

@@ -218,6 +218,9 @@ namespace llarp
           dnsport      = std::atoi(v.substr(pos + 1).c_str());
         }
         m_LocalResolverAddr = llarp::Addr(resolverAddr, dnsport);
+#ifdef _WIN32
+        tunif->bindaddr = m_LocalResolverAddr.ton();
+#endif
         llarp::LogInfo(Name(), " binding DNS server to ", m_LocalResolverAddr);
       }
       if(k == "upstream-dns")

vendor/libtuntap-master/tuntap-windows.c

@@ -417,9 +417,11 @@ tuntap_sys_set_ipv4(struct device *dev, t_tun_in_addr *s, uint32_t mask)
    * inline */
   dns.dhcp_opt = 6;
   dns.length   = 4;
-  dns.value[0] =
-      htonl(0x7F000001); /* apparently this doesn't show in network properties,
+  if (dev->bindaddr)
+    dns.value[0] = dev->bindaddr; /* apparently this doesn't show in network properties,
                             but it works */
+  else
+    dns.value[0] = htonl(0x7f000001);
   dns.value[1] = 0;
 
   ret = DeviceIoControl(dev->tun_fd, TAP_IOCTL_CONFIG_DHCP_SET_OPT, &dns,