Allow RootContext to create child contexts for streams. (#34)

Fixes #6.

Signed-off-by: Daniel Grimm <dgrimm@redhat.com>

Cargo.toml

@@ -60,3 +60,8 @@ crate-type = ["cdylib"]
 name = "http_body"
 path = "examples/http_body.rs"
 crate-type = ["cdylib"]
+
+[[example]]
+name = "http_config"
+path = "examples/http_config.rs"
+crate-type = ["cdylib"]

examples/http_body.rs

@@ -18,7 +18,21 @@ use proxy_wasm::types::*;
 #[no_mangle]
 pub fn _start() {
     proxy_wasm::set_log_level(LogLevel::Trace);
-    proxy_wasm::set_http_context(|_, _| -> Box<dyn HttpContext> { Box::new(HttpBody) });
+    proxy_wasm::set_root_context(|_| -> Box<dyn RootContext> { Box::new(HttpBodyRoot) });
+}
+
+struct HttpBodyRoot;
+
+impl Context for HttpBodyRoot {}
+
+impl RootContext for HttpBodyRoot {
+    fn get_type(&self) -> Option<ContextType> {
+        Some(ContextType::HttpContext)
+    }
+
+    fn create_http_context(&self, _context_id: u32) -> Option<Box<dyn HttpContext>> {
+        Some(Box::new(HttpBody))
+    }
 }
 
 struct HttpBody;

examples/http_config.rs

@@ -0,0 +1,64 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use proxy_wasm::traits::*;
+use proxy_wasm::types::*;
+
+#[no_mangle]
+pub fn _start() {
+    proxy_wasm::set_log_level(LogLevel::Trace);
+    proxy_wasm::set_root_context(|_| -> Box<dyn RootContext> {
+        Box::new(HttpConfigHeaderRoot {
+            header_content: String::new(),
+        })
+    });
+}
+
+struct HttpConfigHeader {
+    header_content: String,
+}
+
+impl Context for HttpConfigHeader {}
+
+impl HttpContext for HttpConfigHeader {
+    fn on_http_response_headers(&mut self, _num_headers: usize) -> Action {
+        self.add_http_response_header("custom-header", self.header_content.as_str());
+        Action::Continue
+    }
+}
+
+struct HttpConfigHeaderRoot {
+    header_content: String,
+}
+
+impl Context for HttpConfigHeaderRoot {}
+
+impl RootContext for HttpConfigHeaderRoot {
+    fn on_configure(&mut self, _plugin_configuration_size: usize) -> bool {
+        if let Some(config_bytes) = self.get_configuration() {
+            self.header_content = String::from_utf8(config_bytes).unwrap()
+        }
+        true
+    }
+
+    fn create_http_context(&self, _context_id: u32) -> Option<Box<dyn HttpContext>> {
+        Some(Box::new(HttpConfigHeader {
+            header_content: self.header_content.clone(),
+        }))
+    }
+
+    fn get_type(&self) -> Option<ContextType> {
+        Some(ContextType::HttpContext)
+    }
+}

examples/http_headers.rs

@@ -19,9 +19,23 @@ use proxy_wasm::types::*;
 #[no_mangle]
 pub fn _start() {
     proxy_wasm::set_log_level(LogLevel::Trace);
-    proxy_wasm::set_http_context(|context_id, _| -> Box<dyn HttpContext> {
-        Box::new(HttpHeaders { context_id })
-    });
+    proxy_wasm::set_root_context(|_| -> Box<dyn RootContext> { Box::new(HttpHeadersRoot) });
+}
+
+struct HttpHeadersRoot;
+
+impl Context for HttpHeadersRoot {}
+
+impl RootContext for HttpHeadersRoot {
+    fn get_type(&self) -> Option<ContextType> {
+        Some(ContextType::HttpContext)
+    }
+
+    fn create_http_context(&self, _context_id: u32) -> Option<Box<dyn HttpContext>> {
+        Some(Box::new(HttpHeaders {
+            context_id: _context_id,
+        }))
+    }
 }
 
 struct HttpHeaders {

src/dispatcher.rs

@@ -80,6 +80,17 @@ impl Dispatcher {
         self.new_http_stream.set(Some(callback));
     }
 
+    fn register_callout(&self, token_id: u32) {
+        if self
+            .callouts
+            .borrow_mut()
+            .insert(token_id, self.active_id.get())
+            .is_some()
+        {
+            panic!("duplicate token_id")
+        }
+    }
+
     fn create_root_context(&self, context_id: u32) {
         let new_context = match self.new_root.get() {
             Some(f) => f(context_id),
@@ -96,12 +107,15 @@ impl Dispatcher {
     }
 
     fn create_stream_context(&self, context_id: u32, root_context_id: u32) {
-        if !self.roots.borrow().contains_key(&root_context_id) {
-            panic!("invalid root_context_id")
-        }
-        let new_context = match self.new_stream.get() {
-            Some(f) => f(context_id, root_context_id),
-            None => panic!("missing constructor"),
+        let new_context = match self.roots.borrow().get(&root_context_id) {
+            Some(root_context) => match self.new_stream.get() {
+                Some(f) => f(context_id, root_context_id),
+                None => match root_context.create_stream_context(context_id) {
+                    Some(stream_context) => stream_context,
+                    None => panic!("create_stream_context returned None"),
+                },
+            },
+            None => panic!("invalid root_context_id"),
         };
         if self
             .streams
@@ -114,12 +128,15 @@ impl Dispatcher {
     }
 
     fn create_http_context(&self, context_id: u32, root_context_id: u32) {
-        if !self.roots.borrow().contains_key(&root_context_id) {
-            panic!("invalid root_context_id")
-        }
-        let new_context = match self.new_http_stream.get() {
-            Some(f) => f(context_id, root_context_id),
-            None => panic!("missing constructor"),
+        let new_context = match self.roots.borrow().get(&root_context_id) {
+            Some(root_context) => match self.new_http_stream.get() {
+                Some(f) => f(context_id, root_context_id),
+                None => match root_context.create_http_context(context_id) {
+                    Some(stream_context) => stream_context,
+                    None => panic!("create_http_context returned None"),
+                },
+            },
+            None => panic!("invalid root_context_id"),
         };
         if self
             .http_streams
@@ -131,26 +148,25 @@ impl Dispatcher {
         }
     }
 
-    fn register_callout(&self, token_id: u32) {
-        if self
-            .callouts
-            .borrow_mut()
-            .insert(token_id, self.active_id.get())
-            .is_some()
-        {
-            panic!("duplicate token_id")
-        }
-    }
-
     fn on_create_context(&self, context_id: u32, root_context_id: u32) {
         if root_context_id == 0 {
-            self.create_root_context(context_id)
+            self.create_root_context(context_id);
         } else if self.new_http_stream.get().is_some() {
             self.create_http_context(context_id, root_context_id);
         } else if self.new_stream.get().is_some() {
             self.create_stream_context(context_id, root_context_id);
+        } else if let Some(root_context) = self.roots.borrow().get(&root_context_id) {
+            match root_context.get_type() {
+                Some(ContextType::HttpContext) => {
+                    self.create_http_context(context_id, root_context_id)
+                }
+                Some(ContextType::StreamContext) => {
+                    self.create_stream_context(context_id, root_context_id)
+                }
+                None => panic!("missing ContextType on root_context"),
+            }
         } else {
-            panic!("missing constructors")
+            panic!("invalid root_context_id and missing constructors");
         }
     }
 

src/traits.rs

@@ -121,6 +121,18 @@ pub trait RootContext: Context {
     fn on_queue_ready(&mut self, _queue_id: u32) {}
 
     fn on_log(&mut self) {}
+
+    fn create_http_context(&self, _context_id: u32) -> Option<Box<dyn HttpContext>> {
+        None
+    }
+
+    fn create_stream_context(&self, _context_id: u32) -> Option<Box<dyn StreamContext>> {
+        None
+    }
+
+    fn get_type(&self) -> Option<ContextType> {
+        None
+    }
 }
 
 pub trait StreamContext: Context {

src/types.rs

@@ -47,6 +47,13 @@ pub enum Status {
     InternalFailure = 10,
 }
 
+#[repr(u32)]
+#[derive(Debug)]
+pub enum ContextType {
+    HttpContext = 0,
+    StreamContext = 1,
+}
+
 #[repr(u32)]
 #[derive(Debug)]
 pub enum BufferType {