2 files changed, 48 insertions, 0 deletions
diff --git a/talpid-core/src/firewall/windows/ffi.rs b/talpid-core/src/firewall/windows/ffi.rs
new file mode 100644
index 0000000000..2cd6c34836
--- /dev/null
+++ b/talpid-core/src/firewall/windows/ffi.rs
@@ -0,0 +1,45 @@
+extern crate libc;
+
+use std::os::raw::c_char;
+use std::ptr;
+
+pub type ErrorSink = extern "system" fn(msg: *const c_char, ctx: *mut libc::c_void);
+
+pub extern "system" fn error_sink(msg: *const c_char, _ctx: *mut libc::c_void) {
+    use std::ffi::CStr;
+    if msg == ptr::null() {
+        error!("Log message from FFI boundary is NULL");
+    } else {
+        error!("{}", unsafe { CStr::from_ptr(msg).to_string_lossy() });
+    }
+}
+
+#[macro_export]
+macro_rules! ffi_error {
+    ($result:ident, $error:expr) => {
+        pub mod $result {
+            use super::*;
+
+            #[repr(C)]
+            #[derive(Debug)]
+            pub struct FFIResult {
+                success: bool,
+            }
+
+            impl FFIResult {
+                pub fn into_result(self) -> Result<()> {
+                    match self.success {
+                        true => Ok(()),
+                        false => Err($error),
+                    }
+                }
+            }
+
+            impl Into<Result<()>> for FFIResult {
+                fn into(self) -> Result<()> {
+                    self.into_result()
+                }
+            }
+        }
+    };
+}
diff --git a/talpid-core/src/firewall/windows/mod.rs b/talpid-core/src/firewall/windows/mod.rs
index f85dc090ca..544843b2f7 100644
--- a/talpid-core/src/firewall/windows/mod.rs
+++ b/talpid-core/src/firewall/windows/mod.rs
@@ -9,6 +9,9 @@ use talpid_types::net::Endpoint;
 
 use self::widestring::WideCString;
 
+#[macro_use]
+mod ffi;
+
 error_chain!{
     errors{
         #[doc = "Windows firewall module error"]