use std::{future::Future, pin::Pin, sync::Arc};
use crate::{
Cancellation, Error,
permission::{Behavior, Decision, Permission, Request},
};
type CheckFuture = Pin<Box<dyn Future<Output = Result<Decision, Error>> + Send + 'static>>;
trait Entry: Send + Sync {
fn check(&self, request: Request, cancellation: Cancellation) -> CheckFuture;
}
struct Typed<P>(Arc<P>);
impl<P: Permission + 'static> Entry for Typed<P> {
fn check(&self, request: Request, cancellation: Cancellation) -> CheckFuture {
let policy = self.0.clone();
Box::pin(async move { policy.check(&request, &cancellation).await })
}
}
#[derive(Clone, Default)]
pub(crate) struct Access(Option<Arc<dyn Entry>>);
impl Access {
pub(crate) fn set<P: Permission + 'static>(&mut self, policy: P) {
self.0 = Some(Arc::new(Typed(Arc::new(policy))));
}
pub(crate) fn is_configured(&self) -> bool {
self.0.is_some()
}
pub(crate) async fn check(
&self,
request: crate::permission::Request,
cancellation: &Cancellation,
) -> Result<Decision, Error> {
if let Some(policy) = &self.0 {
crate::runtime::agent::hooks::cancellable(
policy.check(request, cancellation.clone()),
cancellation,
)
.await
} else {
Err(Error::new(
"INVALID_STATE",
"permission policy is not configured",
))
}
}
}
pub(crate) enum Failure {
Policy(Error),
Hook(Error),
}
#[allow(clippy::too_many_arguments)]
pub(crate) async fn check_permission<K, KF>(
access: &Access,
hooks: &crate::runtime::agent::hooks::Hooks,
mut metadata: serde_json::Map<String, serde_json::Value>,
call: &crate::tool::Call,
saved: Option<crate::runtime::agent::permission::State>,
mut commit: K,
cancellation: &Cancellation,
) -> Result<Decision, Failure>
where
K: FnMut(crate::runtime::agent::permission::State) -> KF,
KF: Future<Output = Result<(), Error>>,
{
metadata.insert(
"call".into(),
serde_json::to_value(call).map_err(|_| {
Failure::Hook(Error::new(
"INVALID_ARGUMENTS",
"cannot encode permission call",
))
})?,
);
let request = Request {
action: "call".into(),
resource: call.name.clone(),
metadata,
};
use crate::runtime::agent::permission::{State, identity};
let mut state = match saved {
Some(state) if state.stage != "complete" => {
state.validate(call, hooks.len()).map_err(Failure::Hook)?;
state
}
_ => State::new(request.clone()),
};
commit(state.clone()).await.map_err(Failure::Hook)?;
if state.stage == "before" {
let input = Box::pin(hooks.apply_from_async(
crate::runtime::agent::hooks::Stage::Permission,
true,
state.input.clone(),
state.idx,
|idx, input: Request| {
let pending = identity(&request, &input).map(|()| {
state.input = input;
state.idx = idx;
commit(state.clone())
});
async move { pending?.await }
},
cancellation,
))
.await
.map_err(Failure::Hook)?;
state.input = input;
state.stage = "check".into();
state.idx = 0;
commit(state.clone()).await.map_err(Failure::Hook)?;
}
let decision = access
.check(state.input.clone(), cancellation)
.await
.map_err(Failure::Policy)?;
if state.stage != "after" {
state.stage = "after".into();
state.idx = 0;
state.output = Some(state.input.clone());
}
state.decision = Some(decision.clone());
commit(state.clone()).await.map_err(Failure::Hook)?;
let output = Box::pin(hooks.apply_from_async(
crate::runtime::agent::hooks::Stage::Permission,
false,
state.output.clone().expect("after Request"),
state.idx,
|idx, output: Request| {
let pending = identity(&state.input, &output).map(|()| {
state.output = Some(output);
state.idx = idx;
commit(state.clone())
});
async move { pending?.await }
},
cancellation,
))
.await
.map_err(Failure::Hook)?;
state.output = Some(output);
state.stage = "complete".into();
commit(state).await.map_err(Failure::Hook)?;
Ok(decision)
}
#[allow(clippy::too_many_arguments)]
pub(crate) async fn check_tool<K, KF>(
access: &Access,
hooks: &crate::runtime::agent::hooks::Hooks,
metadata: serde_json::Map<String, serde_json::Value>,
call: &crate::tool::Call,
cancellation: &Cancellation,
interaction: Option<&crate::runtime::agent::reply::Run>,
id_fn: Option<fn() -> i64>,
approval: Option<&crate::tool::Call>,
saved: Option<crate::runtime::agent::permission::State>,
commit: K,
) -> Result<(), Failure>
where
K: FnMut(crate::runtime::agent::permission::State) -> KF,
KF: Future<Output = Result<(), Error>>,
{
let decision = Box::pin(check_permission(
access,
hooks,
metadata,
call,
saved,
commit,
cancellation,
))
.await?;
match decision.behavior {
Behavior::Allow => Ok(()),
Behavior::Deny => Err(Failure::Policy(Error::new(
"PERMISSION_DENIED",
decision
.reason
.unwrap_or_else(|| "operation denied by permission policy".into()),
))),
Behavior::Ask => {
let reason = decision
.reason
.unwrap_or_else(|| "operation requires user confirmation".into());
if approval == Some(call) {
return Ok(());
}
if let (Some(run), Some(id_fn)) = (interaction, id_fn) {
run.ask(call, &reason, id_fn, cancellation)
.await
.map_err(Failure::Policy)
} else {
Err(Failure::Policy(Error::new("WAITING", reason)))
}
}
}
}
pub(crate) fn require_policy(
steps: &[crate::runtime::agent::node::Step],
configured: bool,
) -> Result<(), Error> {
if !configured
&& steps.iter().any(|step| {
step.permission
.as_ref()
.is_some_and(|state| state.stage != "complete")
})
{
Err(Error::new(
"INVALID_STATE",
"unfinished permission requires its configured policy",
))
} else {
Ok(())
}
}
pub(crate) fn validate_scene(scene: &serde_json::Value, configured: bool) -> Result<(), Error> {
if configured {
return Ok(());
}
let steps: Vec<crate::runtime::agent::node::Step> = scene
.get("steps")
.cloned()
.map(serde_json::from_value)
.transpose()
.map_err(|_| Error::new("INVALID_STATE", "invalid permission owner"))?
.unwrap_or_default();
require_policy(&steps, configured)?;
if let Some(nodes) = scene.get("nodes").and_then(serde_json::Value::as_object) {
for node in nodes.values() {
if let Some(attempt) = node["execution"]["attempts"]
.as_array()
.and_then(|attempts| attempts.last())
{
validate_scene(attempt, configured)?;
}
}
}
Ok(())
}
#[cfg(test)]
mod tests {
use super::{Access, Failure, check_permission, check_tool};
use crate::{
Cancellation,
permission::{Behavior, Decision, Permission, Request},
tool::Call,
};
use serde_json::{Map, Value, json};
use std::sync::{
Arc, Mutex,
atomic::{AtomicBool, Ordering},
};
#[derive(Clone)]
struct Policy {
decision: Decision,
requests: Arc<Mutex<Vec<Request>>>,
}
impl Permission for Policy {
async fn check(
&self,
request: &Request,
_: &Cancellation,
) -> Result<Decision, crate::Error> {
self.requests.lock().unwrap().push(request.clone());
Ok(self.decision.clone())
}
}
#[derive(Clone)]
struct Hook {
name: &'static str,
calls: Arc<Mutex<Vec<&'static str>>>,
change_resource: bool,
change_after: bool,
fail: Option<&'static str>,
}
impl crate::middleware::Middleware for Hook {
async fn before_permission(
&self,
request: &mut Value,
_: &Cancellation,
) -> Result<(), crate::Error> {
self.calls.lock().unwrap().push(self.name);
if self.fail == Some("before") {
return Err(crate::Error::new("HOOK_FAILED", "before hook failed"));
}
if self.change_resource {
request["resource"] = json!("different-operation");
}
Ok(())
}
async fn after_permission(
&self,
request: &mut Value,
_: &Cancellation,
) -> Result<(), crate::Error> {
self.calls.lock().unwrap().push("after");
if self.fail == Some("after") {
return Err(crate::Error::new("HOOK_FAILED", "after hook failed"));
}
if self.change_after {
request["resource"] = json!("different-operation");
}
Ok(())
}
}
fn call() -> Call {
Call {
call_id: "call-live-fact".into(),
name: "lookup".into(),
arguments: serde_json::from_value(json!({"city":"Beijing"})).unwrap(),
}
}
fn policy(behavior: Behavior) -> (Access, Arc<Mutex<Vec<Request>>>) {
let requests = Arc::new(Mutex::new(Vec::new()));
let mut access = Access::default();
access.set(Policy {
decision: Decision {
behavior,
reason: Some("policy reason".into()),
},
requests: requests.clone(),
});
(access, requests)
}
#[tokio::test]
async fn permission_checks_the_actual_call_between_ordered_hooks() {
let (access, requests) = policy(Behavior::Allow);
let calls = Arc::new(Mutex::new(Vec::new()));
let mut hooks = crate::runtime::agent::hooks::Hooks::default();
hooks.add(Hook {
name: "before",
calls: calls.clone(),
change_resource: false,
change_after: false,
fail: None,
});
let mut metadata = Map::new();
metadata.insert("chat_id".into(), json!(101));
let decision = check_permission(
&access,
&hooks,
metadata,
&call(),
None,
|_| std::future::ready(Ok(())),
&Cancellation::new(),
)
.await
.unwrap_or_else(|_| panic!("permission check should complete"));
assert_eq!(decision.behavior, Behavior::Allow);
assert_eq!(*calls.lock().unwrap(), ["before", "after"]);
assert_eq!(requests.lock().unwrap().as_slice(), &[Request {
action: "call".into(),
resource: "lookup".into(),
metadata: serde_json::from_value(json!({
"chat_id":101,
"call":{"call_id":"call-live-fact","name":"lookup","arguments":{"city":"Beijing"}},
})).unwrap(),
}]);
}
#[tokio::test]
async fn deny_is_a_normal_decision_and_policy_failure_stays_technical() {
let (access, _) = policy(Behavior::Deny);
let decision = check_permission(
&access,
&crate::runtime::agent::hooks::Hooks::default(),
Map::new(),
&call(),
None,
|_| std::future::ready(Ok(())),
&Cancellation::new(),
)
.await
.unwrap_or_else(|_| panic!("deny is a normal policy decision"));
assert_eq!(decision.behavior, Behavior::Deny);
struct Broken;
impl Permission for Broken {
async fn check(&self, _: &Request, _: &Cancellation) -> Result<Decision, crate::Error> {
Err(crate::Error::new(
"UNAVAILABLE",
"policy backend unavailable",
))
}
}
let mut access = Access::default();
access.set(Broken);
let error = check_permission(
&access,
&crate::runtime::agent::hooks::Hooks::default(),
Map::new(),
&call(),
None,
|_| std::future::ready(Ok(())),
&Cancellation::new(),
)
.await
.unwrap_err();
assert!(matches!(error, Failure::Policy(error) if error.code == "UNAVAILABLE"));
}
#[tokio::test]
async fn permission_hook_cannot_redirect_the_authorized_operation() {
let (access, requests) = policy(Behavior::Allow);
let mut hooks = crate::runtime::agent::hooks::Hooks::default();
hooks.add(Hook {
name: "redirect",
calls: Arc::default(),
change_resource: true,
change_after: false,
fail: None,
});
let error = check_permission(
&access,
&hooks,
Map::new(),
&call(),
None,
|_| std::future::ready(Ok(())),
&Cancellation::new(),
)
.await
.unwrap_err();
assert!(matches!(error, Failure::Hook(error) if error.code == "INVALID_ARGUMENTS"));
assert!(requests.lock().unwrap().is_empty());
}
#[tokio::test]
async fn tool_gate_distinguishes_allow_deny_ask_and_matching_approval() {
let call = call();
for (behavior, approval, expected) in [
(Behavior::Allow, None, None),
(Behavior::Deny, None, Some("PERMISSION_DENIED")),
(Behavior::Ask, None, Some("WAITING")),
(Behavior::Ask, Some(call.clone()), None),
] {
let (access, requests) = policy(behavior);
let result = check_tool(
&access,
&crate::runtime::agent::hooks::Hooks::default(),
Map::new(),
&call,
&Cancellation::new(),
None,
None,
approval.as_ref(),
None,
|_| std::future::ready(Ok(())),
)
.await;
match expected {
Some(code) => {
assert!(matches!(result, Err(Failure::Policy(error)) if error.code == code))
}
None => assert!(result.is_ok()),
}
assert_eq!(requests.lock().unwrap().len(), 1);
assert_eq!(
requests.lock().unwrap()[0].metadata["call"]["call_id"],
call.call_id
);
}
}
#[tokio::test]
async fn after_hook_cannot_rewrite_a_decision_into_authorizing_another_operation() {
let (access, requests) = policy(Behavior::Allow);
let mut hooks = crate::runtime::agent::hooks::Hooks::default();
hooks.add(Hook {
name: "redirect-after",
calls: Arc::default(),
change_resource: false,
change_after: true,
fail: None,
});
let result = check_tool(
&access,
&hooks,
Map::new(),
&call(),
&Cancellation::new(),
None,
None,
None,
None,
|_| std::future::ready(Ok(())),
)
.await;
assert!(matches!(result, Err(Failure::Hook(error)) if error.code == "INVALID_ARGUMENTS"));
assert_eq!(requests.lock().unwrap().len(), 1);
}
#[tokio::test]
async fn permission_hook_failures_are_control_errors_at_their_actual_stage() {
for stage in ["before", "after"] {
let (access, requests) = policy(Behavior::Allow);
let mut hooks = crate::runtime::agent::hooks::Hooks::default();
hooks.add(Hook {
name: "failure",
calls: Arc::default(),
change_resource: false,
change_after: false,
fail: Some(stage),
});
let error = check_permission(
&access,
&hooks,
Map::new(),
&call(),
None,
|_| std::future::ready(Ok(())),
&Cancellation::new(),
)
.await
.unwrap_err();
assert!(matches!(error, Failure::Hook(error) if error.code == "HOOK_FAILED"));
assert_eq!(
requests.lock().unwrap().len(),
usize::from(stage == "after")
);
}
}
#[tokio::test]
async fn pending_permission_check_is_cancellable_without_retrying_policy() {
struct Pending {
entered: Arc<AtomicBool>,
}
impl Permission for Pending {
async fn check(&self, _: &Request, _: &Cancellation) -> Result<Decision, crate::Error> {
self.entered.store(true, Ordering::SeqCst);
std::future::pending().await
}
}
let entered = Arc::new(AtomicBool::new(false));
let mut access = Access::default();
access.set(Pending {
entered: entered.clone(),
});
let cancellation = Cancellation::new();
let cancel = cancellation.clone();
let cancel_task = tokio::spawn(async move {
while !entered.load(Ordering::SeqCst) {
tokio::task::yield_now().await;
}
cancel.cancel();
});
let error = check_tool(
&access,
&crate::runtime::agent::hooks::Hooks::default(),
Map::new(),
&call(),
&cancellation,
None,
None,
None,
None,
|_| std::future::ready(Ok(())),
)
.await
.unwrap_err();
cancel_task.await.expect("cancel task");
assert!(matches!(error, Failure::Policy(error) if error.code == "CANCELLED"));
}
#[tokio::test]
async fn permission_resume_reuses_acknowledged_hooks_and_rechecks_current_policy() {
struct WaitThenAllow {
requests: Arc<Mutex<Vec<Request>>>,
}
impl Permission for WaitThenAllow {
async fn check(
&self,
request: &Request,
_: &Cancellation,
) -> Result<Decision, crate::Error> {
let mut requests = self.requests.lock().unwrap();
requests.push(request.clone());
if requests.len() == 1 {
Err(crate::Error::new("WAITING", "policy pending"))
} else {
Ok(Decision {
behavior: Behavior::Allow,
reason: None,
})
}
}
}
let requests = Arc::new(Mutex::new(Vec::new()));
let mut access = Access::default();
access.set(WaitThenAllow {
requests: requests.clone(),
});
let calls = Arc::new(Mutex::new(Vec::new()));
let mut hooks = crate::runtime::agent::hooks::Hooks::default();
hooks.add(Hook {
name: "acknowledged",
calls: calls.clone(),
change_resource: false,
change_after: false,
fail: None,
});
let mut saved = None;
let first = check_permission(
&access,
&hooks,
Map::new(),
&call(),
None,
|state| {
saved = Some(state);
std::future::ready(Ok(()))
},
&Cancellation::new(),
)
.await
.unwrap_err();
assert!(matches!(first, Failure::Policy(error) if error.code == "WAITING"));
let saved = saved.expect("the current permission state must be checkpointable");
assert_eq!(saved.stage, "check");
assert!(saved.output.is_none());
assert_eq!(*calls.lock().unwrap(), ["acknowledged"]);
let mut restored = None;
let decision = check_permission(
&access,
&hooks,
Map::new(),
&call(),
Some(saved),
|state| {
restored = Some(state);
std::future::ready(Ok(()))
},
&Cancellation::new(),
)
.await
.unwrap_or_else(|_| panic!("restored permission should recheck and allow"));
assert_eq!(decision.behavior, Behavior::Allow);
assert_eq!(*calls.lock().unwrap(), ["acknowledged", "after"]);
assert_eq!(requests.lock().unwrap().len(), 2);
assert_eq!(restored.expect("final state").stage, "complete");
}
#[tokio::test]
async fn permission_is_rechecked_per_call_and_run_metadata_is_not_cached() {
let (access, requests) = policy(Behavior::Allow);
let call = call();
for chat_id in [201, 202] {
let metadata = Map::from_iter([("chat_id".into(), json!(chat_id))]);
check_tool(
&access,
&crate::runtime::agent::hooks::Hooks::default(),
metadata,
&call,
&Cancellation::new(),
None,
None,
None,
None,
|_| std::future::ready(Ok(())),
)
.await
.unwrap_or_else(|_| panic!("each permission request should be allowed"));
}
let requests = requests.lock().unwrap();
assert_eq!(requests.len(), 2);
assert_eq!(requests[0].metadata["chat_id"], 201);
assert_eq!(requests[1].metadata["chat_id"], 202);
assert_eq!(requests[0].metadata["call"], requests[1].metadata["call"]);
}
#[test]
fn restored_unfinished_permission_requires_policy_at_its_nested_owner() {
use crate::runtime::agent::permission::State;
let mut metadata = Map::new();
metadata.insert("call".into(), serde_json::to_value(call()).unwrap());
let pending = State::new(Request {
action: "call".into(),
resource: "lookup".into(),
metadata,
});
let agent_scene = agent_scene(pending);
let nested_scene = json!({
"nodes": {
"agent-node": {
"execution": {
"attempts": [agent_scene],
},
},
},
});
for scene in [&agent_scene, &nested_scene] {
let error = super::validate_scene(scene, false).unwrap_err();
assert_eq!(error.code, "INVALID_STATE");
assert!(super::validate_scene(scene, true).is_ok());
}
}
#[test]
fn completed_permission_history_does_not_require_a_policy_on_restore() {
use crate::runtime::agent::permission::State;
let mut metadata = Map::new();
metadata.insert("call".into(), serde_json::to_value(call()).unwrap());
let mut completed = State::new(Request {
action: "call".into(),
resource: "lookup".into(),
metadata,
});
completed.stage = "complete".into();
let scene = agent_scene(completed);
assert!(super::validate_scene(&scene, false).is_ok());
}
fn agent_scene(permission: crate::runtime::agent::permission::State) -> Value {
let step = crate::runtime::agent::node::Step {
id: "tool-step".into(),
kind: "tool".into(),
status: "running".into(),
permission: Some(Box::new(permission)),
..Default::default()
};
json!({"steps":[step]})
}
}