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Re: [Openvpn-devel] [PATCH] Setting adapter mtu on windows systems
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From: Christopher S. <cs...@ma...> - 2019-03-29 10:25:38
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Hi,
On 28/03/2019 16:00, Selva Nair wrote:
> I would go a step further to say we should not add new features that
> do not work when started using the interactive service.
>
> Secondly, we should avoid the old style use of netsh and instead use the
> iphelper API as far as possible. It should be possible to
> set MTU using the SetIfEntry() or SetIpInterfaceEnrty() function -- I
> haven't
> checked which one is appropriate here.
I agree on the point that we should add this functionality to the
interactive service as well. So i modified the patch accordingly.
I also modified my patch so that it uses the SetIpInterfaceEnrty
function instead of netsh.
---
diff --git a/include/openvpn-msg.h b/include/openvpn-msg.h
index 66177a21..f59c5a21 100644
--- a/include/openvpn-msg.h
+++ b/include/openvpn-msg.h
@@ -39,6 +39,7 @@ typedef enum {
msg_del_block_dns,
msg_register_dns,
msg_enable_dhcp,
+ msg_set_mtu,
} message_type_t;
typedef struct {
@@ -117,4 +118,11 @@ typedef struct {
interface_t iface;
} enable_dhcp_message_t;
+typedef struct {
+ message_header_t header;
+ interface_t iface;
+ short family;
+ int mtu;
+} set_mtu_message_t;
+
#endif /* ifndef OPENVPN_MSG_H_ */
diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
index 48a8fdf7..9fe8444f 100644
--- a/src/openvpn/tun.c
+++ b/src/openvpn/tun.c
@@ -69,6 +69,10 @@ static void netsh_ifconfig(const struct
tuntap_options *to,
const in_addr_t netmask,
const unsigned int flags);
+static void windows_set_mtu(const int iface_indey,
+ short family,
+ const int mtu);
+
static void netsh_set_dns6_servers(const struct in6_addr *addr_list,
const int addr_len,
const char *flex_name);
@@ -201,6 +205,63 @@ out:
return ret;
}
+static bool
+do_set_mtu_service(const struct tuntap *tt, const short family, const
int mtu)
+{
+ DWORD len;
+ bool ret = false;
+ ack_message_t ack;
+ struct gc_arena gc = gc_new();
+ HANDLE pipe = tt->options.msg_channel;
+
+ set_mtu_message_t mtu_msg = {
+ .header = {
+ msg_set_mtu,
+ sizeof(set_mtu_message_t),
+ 0
+ },
+ .iface = {.index = tt->adapter_index,.name = tt->actual_name },
+ .mtu = mtu,
+ .family = family
+ };
+
+ if (!send_msg_iservice(pipe, &mtu_msg, sizeof(mtu_msg), &ack,
"Set_mtu"))
+ {
+ goto out;
+ }
+
+ if (family == AF_INET)
+ {
+ if (ack.error_number != NO_ERROR)
+ {
+ msg(M_NONFATAL, "TUN: setting IPv4 mtu using service
failed: %s [status=%u if_index=%d]",
+ strerror_win32(ack.error_number, &gc),
ack.error_number, mtu_msg.iface.index);
+ }
+ else
+ {
+ msg(M_INFO, "IPv4 MTU set to %d on interface %d using
service", mtu, mtu_msg.iface.index);
+ ret = true;
+ }
+ }
+ else if (family == AF_INET6)
+ {
+ if (ack.error_number != NO_ERROR)
+ {
+ msg(M_NONFATAL, "TUN: setting IPv6 mtu using service
failed: %s [status=%u if_index=%d]",
+ strerror_win32(ack.error_number, &gc),
ack.error_number, mtu_msg.iface.index);
+ }
+ else
+ {
+ msg(M_INFO, "IPv6 MTU set to %d on interface %d using
service", mtu, mtu_msg.iface.index);
+ ret = true;
+ }
+ }
+
+out:
+ gc_free(&gc);
+ return ret;
+}
+
#endif /* ifdef _WIN32 */
#ifdef TARGET_SOLARIS
@@ -984,6 +1045,7 @@ do_ifconfig_ipv6(struct tuntap *tt, const char
*ifname, int tun_mtu,
{
do_address_service(true, AF_INET6, tt);
do_dns6_service(true, tt);
+ do_set_mtu_service(tt, AF_INET6, tun_mtu);
}
else
{
@@ -1000,6 +1062,7 @@ do_ifconfig_ipv6(struct tuntap *tt, const char
*ifname, int tun_mtu,
netsh_command(&argv, 4, M_FATAL);
/* set ipv6 dns servers if any are specified */
netsh_set_dns6_servers(tt->options.dns6, tt->options.dns6_len,
ifname);
+ windows_set_mtu(tt->adapter_index, AF_INET6, tun_mtu);
}
/* explicit route needed */
@@ -1391,9 +1454,16 @@ do_ifconfig_ipv4(struct tuntap *tt, const char
*ifname, int tun_mtu,
case IPW32_SET_NETSH:
netsh_ifconfig(&tt->options, ifname, tt->local,
tt->adapter_netmask,
NI_IP_NETMASK|NI_OPTIONS);
-
break;
}
+ if (tt->options.msg_channel)
+ {
+ do_set_mtu_service(tt, AF_INET, tun_mtu);
+ }
+ else
+ {
+ windows_set_mtu(tt->adapter_index, AF_INET, tun_mtu);
+ }
}
#else /* if defined(TARGET_LINUX) */
@@ -5236,6 +5306,46 @@ out:
return ret;
}
+static void
+windows_set_mtu(const int iface_index, const short family,
+ const int mtu)
+{
+ DWORD err = 0;
+ struct gc_arena gc = gc_new();
+ MIB_IPINTERFACE_ROW row;
+ InitializeIpInterfaceEntry(&row);
+ row.Family = family;
+ row.InterfaceIndex = iface_index;
+ row.NlMtu = mtu;
+
+ err = SetIpInterfaceEntry(&row);
+ if (family == AF_INET)
+ {
+ if (err != NO_ERROR)
+ {
+ msg(M_WARN, "TUN: Setting IPv4 mtu failed: %s [status=%u
if_index=%d]",
+ strerror_win32(err, &gc), err, iface_index);
+ }
+ else
+ {
+ msg(M_INFO, "Successfully set IPv4 mtu on interface %d",
iface_index);
+ }
+ }
+ else if (family == AF_INET6)
+ {
+ if (err != NO_ERROR)
+ {
+ msg(M_WARN, "TUN: Setting IPv6 mtu failed: %s [status=%u
if_index=%d]",
+ strerror_win32(err, &gc), err, iface_index);
+ }
+ else
+ {
+ msg(M_INFO, "Successfully set IPv6 mtu on interface %d",
iface_index);
+ }
+ }
+}
+
+
/*
* Return a TAP name for netsh commands.
*/
diff --git a/src/openvpnserv/interactive.c b/src/openvpnserv/interactive.c
index 623c3ff7..6e6a63fe 100644
--- a/src/openvpnserv/interactive.c
+++ b/src/openvpnserv/interactive.c
@@ -33,6 +33,7 @@
#include <sddl.h>
#include <shellapi.h>
#include <mstcpip.h>
+#include <netioapi.h>
#ifdef HAVE_VERSIONHELPERS_H
#include <versionhelpers.h>
@@ -1198,6 +1199,20 @@ HandleEnableDHCPMessage(const
enable_dhcp_message_t *dhcp)
return err;
}
+static DWORD
+HandleMTUMessage(const set_mtu_message_t *mtu)
+{
+ DWORD err = 0;
+ MIB_IPINTERFACE_ROW row;
+ InitializeIpInterfaceEntry(&row);
+ row.Family = mtu->family;
+ row.InterfaceIndex = mtu->iface.index;
+ row.NlMtu = mtu->mtu;
+
+ err = SetIpInterfaceEntry(&row);
+ return err;
+}
+
static VOID
HandleMessage(HANDLE pipe, DWORD bytes, DWORD count, LPHANDLE events,
undo_lists_t *lists)
{
@@ -1210,6 +1225,7 @@ HandleMessage(HANDLE pipe, DWORD bytes, DWORD
count, LPHANDLE events, undo_lists
block_dns_message_t block_dns;
dns_cfg_message_t dns;
enable_dhcp_message_t dhcp;
+ set_mtu_message_t mtu;
} msg;
ack_message_t ack = {
.header = {
@@ -1276,6 +1292,12 @@ HandleMessage(HANDLE pipe, DWORD bytes, DWORD
count, LPHANDLE events, undo_lists
ack.error_number = HandleEnableDHCPMessage(&msg.dhcp);
}
break;
+ case msg_set_mtu:
+ if (msg.header.size == sizeof(msg.mtu))
+ {
+ ack.error_number = HandleMTUMessage(&msg.mtu);
+ }
+ break;
default:
ack.error_number = ERROR_MESSAGE_TYPE;
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