brokerd: memory calls to memoryd with the session's state; labels only stricter

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/brokerd/src/memory_port.rs

@@ -0,0 +1,119 @@
+//! Where decided `recall` and `memory` calls go: to `memoryd` over its `brokerd` socket, with the
+//! session's state, instead of a container (M5a spec, section 8). `Routed` sends every other call
+//! to the configured runtime.
+
+use std::os::unix::net::UnixStream;
+use std::path::PathBuf;
+use std::time::Duration;
+
+use proto::{
+    Envelope, MemoryCall, Message, PROTOCOL_VERSION, ToolRequest, ToolResponse, read_frame,
+    write_frame,
+};
+
+use crate::policy::Label;
+use crate::runner::{RunError, RunOutput, RunSpec, Runtime};
+
+/// The sentence when `memoryd` cannot be reached or answers wrongly: fixed, it reaches the model.
+pub const UNREACHABLE: &str =
+    "memory is unavailable: memoryd did not answer (see docs/runbook.md#memoryd-unreachable)";
+
+/// How long `brokerd` waits for `memoryd` to answer one call.
+pub const MEMORY_WAIT: Duration = Duration::from_secs(30);
+
+/// A client of `memoryd`'s `brokerd` socket. One connection per call.
+pub struct MemoryPort {
+    socket: PathBuf,
+    wait: Duration,
+}
+
+impl MemoryPort {
+    pub fn new(socket: PathBuf, wait: Duration) -> MemoryPort {
+        MemoryPort { socket, wait }
+    }
+
+    fn ask(&self, spec: &RunSpec) -> Option<ToolResponse> {
+        // `None` at the first thing that fails. 1. A MemoryCall: request with the spec's session,
+        // call, `spec.tool().as_str()`, and `spec.arguments().canonical_json()`; taint and
+        // untrusted from `spec.state()`. 2. `UnixStream::connect(&self.socket)`, then read and
+        // write timeouts of `self.wait`. 3. `write_frame` an Envelope { v: PROTOCOL_VERSION, id:
+        // spec.call().0, final: true, msg: Message::MemoryCall(call) }. 4. `read_frame`; a
+        // Message::ToolResponse is Some(it), any other message None.
+        let call = MemoryCall {
+            request: ToolRequest {
+                session: spec.session().clone(),
+                call: spec.call(),
+                tool: spec.tool().as_str().to_string(),
+                arguments: spec.arguments().canonical_json(),
+            },
+            taint: spec.state().taint,
+            untrusted: spec.state().untrusted,
+        };
+        let mut stream = UnixStream::connect(&self.socket).ok()?;
+        stream.set_read_timeout(Some(self.wait)).ok()?;
+        stream.set_write_timeout(Some(self.wait)).ok()?;
+        write_frame(
+            &mut stream,
+            &Envelope {
+                v: PROTOCOL_VERSION,
+                id: spec.call().0,
+                r#final: true,
+                msg: Message::MemoryCall(call),
+            },
+        )
+        .ok()?;
+        let env = read_frame(&mut stream).ok()?;
+        match env.msg {
+            Message::ToolResponse(response) => Some(response),
+            _ => None,
+        }
+    }
+}
+
+impl Runtime for MemoryPort {
+    fn run(&self, spec: &RunSpec) -> Result<RunOutput, RunError> {
+        self.run_labelled(spec).map(|(output, _)| output)
+    }
+
+    fn run_labelled(&self, spec: &RunSpec) -> Result<(RunOutput, Option<Label>), RunError> {
+        // `self.ask(spec)`: Some(Result { content, class, untrusted, truncated }) -> Ok((RunOutput
+        // { content, truncated }, Some(Label { class, untrusted }))); Some(Failed { message }) ->
+        // Err(RunError::Failed(message)); anything else, None included ->
+        // Err(RunError::Unavailable(UNREACHABLE.to_string())).
+        match self.ask(spec) {
+            Some(ToolResponse::Result {
+                content,
+                class,
+                untrusted,
+                truncated,
+            }) => Ok((
+                RunOutput { content, truncated },
+                Some(Label { class, untrusted }),
+            )),
+            Some(ToolResponse::Failed { message }) => Err(RunError::Failed(message)),
+            _ => Err(RunError::Unavailable(UNREACHABLE.to_string())),
+        }
+    }
+}
+
+/// The memory tools to `memoryd`, everything else to `other`.
+pub struct Routed {
+    pub memory: MemoryPort,
+    pub other: Box<dyn Runtime>,
+}
+
+impl Runtime for Routed {
+    fn run(&self, spec: &RunSpec) -> Result<RunOutput, RunError> {
+        self.run_labelled(spec).map(|(output, _)| output)
+    }
+
+    fn run_labelled(&self, spec: &RunSpec) -> Result<(RunOutput, Option<Label>), RunError> {
+        // `spec.tool().is_memory()` -> `self.memory.run_labelled(spec)`; otherwise
+        // `self.other.run_labelled(spec)`.
+        if spec.tool().is_memory() {
+            self.memory.run_labelled(spec)
+        } else {
+            self.other.run_labelled(spec)
+        }
+    }
+}