driver: socket: bypass TDI entirely

Not only will this improve performance, but it will eliminate a big
issue with IP_PKTINFO.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

2 files changed, 12 insertions, 4 deletions

diff --git a/TODO.md b/TODO.md
index 0b5c515..7c2ed44 100644
--- a/TODO.md
+++ b/TODO.md
@@ -28,10 +28,6 @@ mode -- the routing logic ignores `IP_PKTINFO`. This seems like a bug, but one
 unlikely to be fixed. We'll need a opt-in `setsockopt` to make `IP_PKTINFO`
 choose the right behavior in this case.
 
-### TDI drivers never do the right thing with `IP_PKTINFO`
-Windows only looks at Options/OptionsLength if UserBuffer==(PVOID)0x886103.
-This is crazy, so nobody actually does it.
-
 ## Bug workarounds
 
 ### Remove `_NO_CRT_STDIO_INLINE` once WDK is fixed
diff --git a/driver/socket.c b/driver/socket.c
index 11e402b..466daac 100644
--- a/driver/socket.c
+++ b/driver/socket.c
@@ -991,6 +991,18 @@ WskInit(VOID)
     if (!NT_SUCCESS(Status))
         goto cleanupWskProviderNPI;
 
+    /* Ignore return value, as MSDN says eventually this will be removed. */
+    ULONG NoTdi = WSK_TDI_BEHAVIOR_BYPASS_TDI;
+    WskProviderNpi.Dispatch->WskControlClient(
+        WskProviderNpi.Client,
+        WSK_TDI_BEHAVIOR,
+        sizeof(NoTdi),
+        &NoTdi,
+        0,
+        NULL,
+        NULL,
+        NULL);
+
     Status = NotifyRouteChange2(AF_INET, RouteNotification, &RoutingGenerationV4, FALSE, &RouteNotifierV4);
     if (!NT_SUCCESS(Status))
         goto cleanupWskProviderNPI;