Add support for foreign function callbacks. (#290)

Signed-off-by: Caio Ramos Casimiro <caiorcasimiro@gmail.com>

Author: casimiro

src/dispatcher.rs

@@ -554,6 +554,22 @@ impl Dispatcher {
             }
         }
     }
+
+    fn on_foreign_function(&self, context_id: u32, function_id: u32, arugments_size: usize) {
+        if let Some(http_stream) = self.http_streams.borrow_mut().get_mut(&context_id) {
+            self.active_id.set(context_id);
+            hostcalls::set_effective_context(context_id).unwrap();
+            http_stream.on_foreign_function(function_id, arugments_size)
+        } else if let Some(stream) = self.streams.borrow_mut().get_mut(&context_id) {
+            self.active_id.set(context_id);
+            hostcalls::set_effective_context(context_id).unwrap();
+            stream.on_foreign_function(function_id, arugments_size)
+        } else if let Some(root) = self.roots.borrow_mut().get_mut(&context_id) {
+            self.active_id.set(context_id);
+            hostcalls::set_effective_context(context_id).unwrap();
+            root.on_foreign_function(function_id, arugments_size)
+        }
+    }
 }
 
 #[no_mangle]
@@ -722,3 +738,13 @@ pub extern "C" fn proxy_on_grpc_receive_trailing_metadata(
 pub extern "C" fn proxy_on_grpc_close(_context_id: u32, token_id: u32, status_code: u32) {
     DISPATCHER.with(|dispatcher| dispatcher.on_grpc_close(token_id, status_code))
 }
+
+#[no_mangle]
+pub extern "C" fn proxy_on_foreign_function(
+    context_id: u32,
+    function_id: u32,
+    arguments_size: usize,
+) {
+    DISPATCHER
+        .with(|dispatcher| dispatcher.on_foreign_function(context_id, function_id, arguments_size))
+}

src/traits.rs

@@ -197,6 +197,8 @@ pub trait Context {
         hostcalls::get_grpc_status().unwrap()
     }
 
+    fn on_foreign_function(&mut self, _function_id: u32, _arguments_size: usize) {}
+
     fn call_foreign_function(
         &self,
         function_name: &str,

src/types.rs

@@ -81,6 +81,7 @@ pub enum BufferType {
     GrpcReceiveBuffer = 5,
     VmConfiguration = 6,
     PluginConfiguration = 7,
+    CallData = 8,
 }
 
 #[repr(u32)]