use crate::endpoint::{
EndpointKind,
parse::{AccessExprAst, AccessPredicateAst, AuthScopeArg, BuiltinPredicate},
validate::ValidatedArgs,
};
use proc_macro2::TokenStream as TokenStream2;
use quote::{format_ident, quote};
use syn::{GenericArgument, ItemFn, PathArguments, Signature, Type, visit::Visit};
#[expect(clippy::default_trait_access)]
pub fn expand(kind: EndpointKind, args: ValidatedArgs, mut func: ItemFn) -> TokenStream2 {
let attrs = func.attrs.clone();
let orig_sig = func.sig.clone();
let orig_name = orig_sig.ident.clone();
let vis = func.vis.clone();
let inputs = orig_sig.inputs.clone();
let output = orig_sig.output.clone();
let impl_async = orig_sig.asyncness.is_some();
let returns_fallible = returns_fallible(&orig_sig);
let access_plan = match build_access_plan(kind, &args, &orig_sig) {
Ok(plan) => plan,
Err(err) => return err.to_compile_error(),
};
if !returns_fallible && !matches!(access_plan, AccessPlan::None) {
let message = "access-gated endpoints must return Result<_, Error> to avoid traps";
return syn::Error::new_spanned(&orig_sig.ident, message).to_compile_error();
}
let wrapper_async = impl_async || access_plan.requires_async();
let impl_name = format_ident!("__canic_impl_{}", orig_name);
func.sig.ident = impl_name.clone();
if requires_authenticated(&args.requires)
&& let Some(first_arg_ident) = first_typed_arg_ident(&orig_sig)
{
let keepalive: syn::Stmt = syn::parse_quote!(let _ = &#first_arg_ident;);
func.block.stmts.insert(0, keepalive);
}
let cdk_attr = cdk_attr(kind, &args.forwarded);
let payload_registration = payload_registration(kind, &args, &orig_name);
let dispatch_fn = dispatch(kind, wrapper_async);
let wrapper_sig = syn::Signature {
ident: orig_name.clone(),
asyncness: if wrapper_async {
Some(Default::default())
} else {
None
},
inputs,
output,
..orig_sig.clone()
};
let call_ident = format_ident!("__canic_call");
let call_decl = call_decl(kind, &call_ident, &orig_name);
let access_stage = access_stage(&access_plan, &call_ident);
let call_args = match extract_args(&orig_sig) {
Ok(v) => v,
Err(e) => return e.to_compile_error(),
};
let dispatch_call = dispatch_call(
wrapper_async,
impl_async,
dispatch_fn,
&call_ident,
impl_name,
&call_args,
);
quote! {
#payload_registration
#(#attrs)*
#[expect(clippy::missing_const_for_fn, clippy::unnecessary_wraps)]
#cdk_attr
#vis #wrapper_sig {
#call_decl
#access_stage
#dispatch_call
}
#[expect(clippy::missing_const_for_fn, clippy::unnecessary_wraps)]
#func
}
}
fn returns_fallible(sig: &syn::Signature) -> bool {
let syn::ReturnType::Type(_, ty) = &sig.output else {
return false;
};
let syn::Type::Path(ty) = &**ty else {
return false;
};
ty.path
.segments
.last()
.is_some_and(|seg| seg.ident == "Result")
}
fn dispatch(kind: EndpointKind, asyncness: bool) -> TokenStream2 {
match (kind, asyncness) {
(EndpointKind::Query, false) => {
quote!(::canic::__internal::core::dispatch::dispatch_query)
}
(EndpointKind::Query, true) => {
quote!(::canic::__internal::core::dispatch::dispatch_query_async)
}
(EndpointKind::Update, false) => {
quote!(::canic::__internal::core::dispatch::dispatch_update)
}
(EndpointKind::Update, true) => {
quote!(::canic::__internal::core::dispatch::dispatch_update_async)
}
}
}
fn payload_registration(
kind: EndpointKind,
args: &ValidatedArgs,
name: &syn::Ident,
) -> TokenStream2 {
if !matches!(kind, EndpointKind::Update) {
return quote!();
}
let register_name = format_ident!("__canic_register_payload_limit_{}", name);
let ctor_name = format_ident!("__canic_ctor_payload_limit_{}", name);
let method_name = if let Some(name) = &args.export_name {
quote!(#name)
} else {
quote!(stringify!(#name))
};
let max_bytes = args.payload_max_bytes.clone().unwrap_or_else(|| {
quote!(::canic::__internal::core::ingress::payload::DEFAULT_UPDATE_INGRESS_MAX_BYTES)
});
quote! {
const _: () = {
fn #register_name() {
::canic::__internal::core::ingress::payload::register_update_limit(
#method_name,
#max_bytes,
);
}
#[ ::canic::__internal::core::__reexports::ctor::ctor(
unsafe,
anonymous,
crate_path = ::canic::__internal::core::__reexports::ctor
) ]
fn #ctor_name() {
#register_name();
}
};
}
}
fn call_decl(kind: EndpointKind, call: &syn::Ident, name: &syn::Ident) -> TokenStream2 {
let call_kind = match kind {
EndpointKind::Query => {
quote!(::canic::__internal::core::ids::EndpointCallKind::Query)
}
EndpointKind::Update => {
quote!(::canic::__internal::core::ids::EndpointCallKind::Update)
}
};
quote! {
let #call = ::canic::__internal::core::ids::EndpointCall {
endpoint: ::canic::__internal::core::ids::EndpointId::new(stringify!(#name)),
kind: #call_kind,
};
}
}
fn access_stage(plan: &AccessPlan, call: &syn::Ident) -> TokenStream2 {
let caller = format_ident!("__canic_caller");
let authenticated_identity = format_ident!("__canic_authenticated_identity");
let ctx = format_ident!("__canic_access_ctx");
let deny = quote!(return Err(err.into()););
match plan {
AccessPlan::None => quote!(),
AccessPlan::DefaultApp(guard) => {
let guard_expr = guard_tokens(*guard);
quote! {
let #caller = ::canic::cdk::api::msg_caller();
let #ctx = ::canic::__internal::core::access::expr::AccessContext {
caller: #caller,
authenticated_caller: #caller,
identity_source: ::canic::__internal::core::access::auth::AuthenticatedIdentitySource::RawCaller,
call: #call,
};
if let Err(err) = ::canic::__internal::core::access::expr::eval_default_app_guard(
#guard_expr,
&#ctx,
) {
#deny
}
}
}
AccessPlan::Expr(expr) => {
let expr_ident = format_ident!("__canic_access_expr");
quote! {
let #caller = ::canic::cdk::api::msg_caller();
let #authenticated_identity =
::canic::__internal::core::access::auth::resolve_authenticated_identity(#caller);
let #ctx = ::canic::__internal::core::access::expr::AccessContext {
caller: #authenticated_identity.transport_caller,
authenticated_caller: #authenticated_identity.authenticated_subject,
identity_source: #authenticated_identity.identity_source,
call: #call,
};
let #expr_ident = #expr;
if let Err(err) = ::canic::__internal::core::access::expr::eval_access(&#expr_ident, &#ctx).await {
#deny
}
}
}
}
}
#[derive(Clone, Copy, Debug)]
enum DefaultAppGuard {
AllowsUpdates,
IsQueryable,
}
#[derive(Debug)]
enum AccessPlan {
None,
DefaultApp(DefaultAppGuard),
Expr(TokenStream2),
}
impl AccessPlan {
const fn requires_async(&self) -> bool {
matches!(self, Self::Expr(_))
}
}
fn guard_tokens(guard: DefaultAppGuard) -> TokenStream2 {
match guard {
DefaultAppGuard::AllowsUpdates => {
quote!(::canic::__internal::core::access::expr::DefaultAppGuard::AllowsUpdates)
}
DefaultAppGuard::IsQueryable => {
quote!(::canic::__internal::core::access::expr::DefaultAppGuard::IsQueryable)
}
}
}
fn build_access_plan(
kind: EndpointKind,
args: &ValidatedArgs,
sig: &Signature,
) -> syn::Result<AccessPlan> {
let is_app_command = is_app_command_endpoint(sig);
let is_internal = args.internal || is_app_command;
let has_app_state = exprs_have_app_state_predicate(&args.requires);
if is_internal && has_app_state {
let message = if is_app_command {
"AppCommand endpoints must never be gated on application state."
} else {
"Internal protocol endpoints must never be gated on application state."
};
return Err(syn::Error::new_spanned(&sig.ident, message));
}
let mut exprs = args.requires.clone();
if !is_internal && !has_app_state {
if exprs.is_empty() {
let default_guard = match kind {
EndpointKind::Update => DefaultAppGuard::AllowsUpdates,
EndpointKind::Query => DefaultAppGuard::IsQueryable,
};
return Ok(AccessPlan::DefaultApp(default_guard));
}
let injected = match kind {
EndpointKind::Update => BuiltinPredicate::AppAllowsUpdates,
EndpointKind::Query => BuiltinPredicate::AppIsQueryable,
};
exprs.push(AccessExprAst::Pred(AccessPredicateAst::Builtin(injected)));
}
if exprs.is_empty() {
return Ok(AccessPlan::None);
}
let exprs: Vec<_> = exprs.iter().map(expr_from_ast).collect();
Ok(AccessPlan::Expr(quote! {
::canic::__internal::core::access::expr::AccessExpr::All(vec![#(#exprs),*])
}))
}
fn expr_from_ast(expr: &AccessExprAst) -> TokenStream2 {
match expr {
AccessExprAst::All(exprs) => {
let items = exprs.iter().map(expr_from_ast);
quote!(::canic::__internal::core::access::expr::AccessExpr::All(
vec![#(#items),*]
))
}
AccessExprAst::Any(exprs) => {
let items = exprs.iter().map(expr_from_ast);
quote!(::canic::__internal::core::access::expr::AccessExpr::Any(
vec![#(#items),*]
))
}
AccessExprAst::Not(expr) => {
let inner = expr_from_ast(expr);
quote!(::canic::__internal::core::access::expr::AccessExpr::Not(Box::new(#inner)))
}
AccessExprAst::Pred(pred) => match pred {
AccessPredicateAst::Builtin(builtin) => expr_from_builtin(builtin),
AccessPredicateAst::Custom(expr) => {
quote!(::canic::__internal::core::access::expr::custom(#expr))
}
},
}
}
fn expr_from_builtin(pred: &BuiltinPredicate) -> TokenStream2 {
match pred {
BuiltinPredicate::AppAllowsUpdates => {
quote!(::canic::__internal::core::access::expr::app::allows_updates())
}
BuiltinPredicate::AppIsQueryable => {
quote!(::canic::__internal::core::access::expr::app::is_queryable())
}
BuiltinPredicate::SelfIsPrimeSubnet => {
quote!(::canic::__internal::core::access::expr::env::is_prime_subnet())
}
BuiltinPredicate::SelfIsPrimeRoot => {
quote!(::canic::__internal::core::access::expr::env::is_prime_root())
}
BuiltinPredicate::CallerIsController => {
quote!(::canic::__internal::core::access::expr::caller::is_controller())
}
BuiltinPredicate::CallerIsParent => {
quote!(::canic::__internal::core::access::expr::caller::is_parent())
}
BuiltinPredicate::CallerIsChild => {
quote!(::canic::__internal::core::access::expr::caller::is_child())
}
BuiltinPredicate::CallerIsRoot => {
quote!(::canic::__internal::core::access::expr::caller::is_root())
}
BuiltinPredicate::CallerIsSameCanister => {
quote!(::canic::__internal::core::access::expr::caller::is_same_canister())
}
BuiltinPredicate::CallerIsRegisteredToSubnet => {
quote!(::canic::__internal::core::access::expr::caller::is_registered_to_subnet())
}
BuiltinPredicate::CallerIsWhitelisted => {
quote!(::canic::__internal::core::access::expr::caller::is_whitelisted())
}
BuiltinPredicate::Authenticated { required_scope } => match required_scope {
Some(AuthScopeArg::Literal(required_scope)) => quote!(
::canic::__internal::core::access::expr::auth::authenticated_with_scope(
#required_scope
)
),
Some(AuthScopeArg::Expr(required_scope)) => quote!(
::canic::__internal::core::access::expr::auth::authenticated_with_scope(
#required_scope
)
),
None => quote!(
::canic::__internal::core::access::expr::auth::authenticated(
::core::option::Option::None
)
),
},
BuiltinPredicate::BuildIcOnly => {
quote!(::canic::__internal::core::access::expr::env::build_ic_only())
}
BuiltinPredicate::BuildLocalOnly => {
quote!(::canic::__internal::core::access::expr::env::build_local_only())
}
}
}
fn exprs_have_app_state_predicate(exprs: &[AccessExprAst]) -> bool {
exprs.iter().any(expr_has_app_state_predicate)
}
fn requires_authenticated(exprs: &[AccessExprAst]) -> bool {
exprs.iter().any(expr_has_authenticated_predicate)
}
fn expr_has_authenticated_predicate(expr: &AccessExprAst) -> bool {
match expr {
AccessExprAst::All(exprs) | AccessExprAst::Any(exprs) => {
exprs.iter().any(expr_has_authenticated_predicate)
}
AccessExprAst::Not(expr) => expr_has_authenticated_predicate(expr),
AccessExprAst::Pred(pred) => match pred {
AccessPredicateAst::Builtin(builtin) => {
matches!(builtin, BuiltinPredicate::Authenticated { .. })
}
AccessPredicateAst::Custom(_) => false,
},
}
}
fn first_typed_arg_ident(sig: &Signature) -> Option<syn::Ident> {
let first = sig.inputs.first()?;
let syn::FnArg::Typed(pat) = first else {
return None;
};
let syn::Pat::Ident(id) = &*pat.pat else {
return None;
};
Some(id.ident.clone())
}
fn expr_has_app_state_predicate(expr: &AccessExprAst) -> bool {
match expr {
AccessExprAst::All(exprs) | AccessExprAst::Any(exprs) => {
exprs.iter().any(expr_has_app_state_predicate)
}
AccessExprAst::Not(expr) => expr_has_app_state_predicate(expr),
AccessExprAst::Pred(pred) => match pred {
AccessPredicateAst::Builtin(builtin) => builtin_is_app_state(builtin),
AccessPredicateAst::Custom(tokens) => custom_has_app_state_is(tokens),
},
}
}
const fn builtin_is_app_state(pred: &BuiltinPredicate) -> bool {
matches!(
pred,
BuiltinPredicate::AppAllowsUpdates | BuiltinPredicate::AppIsQueryable
)
}
fn custom_has_app_state_is(tokens: &TokenStream2) -> bool {
let Ok(expr) = syn::parse2::<syn::Expr>(tokens.clone()) else {
return false;
};
let mut visitor = AppStateVisitor { found: false };
visitor.visit_expr(&expr);
visitor.found
}
struct AppStateVisitor {
found: bool,
}
impl Visit<'_> for AppStateVisitor {
fn visit_path(&mut self, path: &syn::Path) {
if path.segments.iter().any(|seg| seg.ident == "AppStateIs") {
self.found = true;
return;
}
syn::visit::visit_path(self, path);
}
}
fn is_app_command_endpoint(sig: &Signature) -> bool {
sig.inputs.iter().any(|input| match input {
syn::FnArg::Typed(pat) => type_has_app_command(&pat.ty),
syn::FnArg::Receiver(_) => true,
})
}
fn type_has_app_command(ty: &Type) -> bool {
match ty {
Type::Path(path) => path_has_app_command(&path.path),
Type::Reference(reference) => type_has_app_command(&reference.elem),
Type::Group(group) => type_has_app_command(&group.elem),
Type::Paren(paren) => type_has_app_command(&paren.elem),
Type::Tuple(tuple) => tuple.elems.iter().any(type_has_app_command),
_ => false,
}
}
fn path_has_app_command(path: &syn::Path) -> bool {
path.segments.iter().any(|seg| {
if seg.ident == "AppCommand" {
return true;
}
match &seg.arguments {
PathArguments::AngleBracketed(args) => args.args.iter().any(|arg| match arg {
GenericArgument::Type(ty) => type_has_app_command(ty),
_ => false,
}),
_ => false,
}
})
}
fn dispatch_call(
wrapper_async: bool,
impl_async: bool,
dispatch: TokenStream2,
call: &syn::Ident,
impl_name: syn::Ident,
args: &[TokenStream2],
) -> TokenStream2 {
if wrapper_async {
if impl_async {
quote! {
#dispatch(#call, || async move {
#impl_name(#(#args),*).await
}).await
}
} else {
quote! {
#dispatch(#call, || async move {
#impl_name(#(#args),*)
}).await
}
}
} else {
quote! {
#dispatch(#call, || {
#impl_name(#(#args),*)
})
}
}
}
fn extract_args(sig: &syn::Signature) -> syn::Result<Vec<TokenStream2>> {
let mut out = Vec::new();
for input in &sig.inputs {
match input {
syn::FnArg::Typed(pat) => match &*pat.pat {
syn::Pat::Ident(id) => out.push(quote!(#id)),
_ => {
return Err(syn::Error::new_spanned(
&pat.pat,
"destructuring parameters not supported",
));
}
},
syn::FnArg::Receiver(r) => {
return Err(syn::Error::new_spanned(
r,
"`self` not supported in canic endpoints",
));
}
}
}
Ok(out)
}
fn cdk_attr(kind: EndpointKind, forwarded: &[TokenStream2]) -> TokenStream2 {
match kind {
EndpointKind::Query => {
if forwarded.is_empty() {
quote!(#[::canic::cdk::query])
} else {
quote!(#[::canic::cdk::query(#(#forwarded),*)])
}
}
EndpointKind::Update => {
if forwarded.is_empty() {
quote!(#[::canic::cdk::update])
} else {
quote!(#[::canic::cdk::update(#(#forwarded),*)])
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
fn make_args(requires: Vec<AccessExprAst>) -> ValidatedArgs {
ValidatedArgs {
forwarded: Vec::new(),
export_name: None,
payload_max_bytes: None,
requires,
internal: false,
}
}
#[test]
fn endpoint_expansion_omits_removed_endpoint_metric_hooks() {
let args = make_args(Vec::new());
let func: ItemFn = syn::parse_quote!(
fn ping() -> Result<(), ::canic::Error> {
Ok(())
}
);
let expanded = expand(EndpointKind::Query, args, func).to_string();
assert!(!expanded.contains("EndpointAttemptMetrics"));
assert!(!expanded.contains("EndpointResultMetrics"));
}
#[test]
fn update_expansion_registers_payload_limit_for_exported_name() {
let mut args = make_args(Vec::new());
args.export_name = Some(syn::LitStr::new(
"wire_ping",
proc_macro2::Span::call_site(),
));
args.payload_max_bytes = Some(quote!(64 * 1024));
let func: ItemFn = syn::parse_quote!(
fn ping() -> Result<(), ::canic::Error> {
Ok(())
}
);
let expanded = expand(EndpointKind::Update, args, func).to_string();
assert!(expanded.contains("register_update_limit"));
assert!(expanded.contains("\"wire_ping\""));
assert!(expanded.contains("64 * 1024"));
}
#[test]
fn default_app_guard_keeps_sync_wrapper_sync() {
let sig: Signature = syn::parse_quote!(fn ping() -> Result<(), ::canic::Error>);
let args = make_args(Vec::new());
let plan = build_access_plan(EndpointKind::Update, &args, &sig).expect("access plan");
assert!(!plan.requires_async());
assert!(!(sig.asyncness.is_some() || plan.requires_async()));
}
#[test]
fn explicit_requires_forces_async_wrapper() {
let sig: Signature = syn::parse_quote!(fn ping() -> Result<(), ::canic::Error>);
let args = make_args(vec![AccessExprAst::Pred(AccessPredicateAst::Builtin(
BuiltinPredicate::CallerIsController,
))]);
let plan = build_access_plan(EndpointKind::Update, &args, &sig).expect("access plan");
assert!(plan.requires_async());
assert!(sig.asyncness.is_some() || plan.requires_async());
}
#[test]
fn app_command_endpoints_skip_app_guard_and_reject_gating() {
let sig: Signature = syn::parse_quote!(
fn apply(cmd: ::canic::dto::state::AppCommand) -> Result<(), ::canic::Error>
);
let args = make_args(Vec::new());
let plan = build_access_plan(EndpointKind::Update, &args, &sig).expect("access plan");
assert!(matches!(plan, AccessPlan::None));
let args = make_args(vec![AccessExprAst::Pred(AccessPredicateAst::Builtin(
BuiltinPredicate::AppAllowsUpdates,
))]);
let err = build_access_plan(EndpointKind::Update, &args, &sig).unwrap_err();
assert!(
err.to_string()
.contains("AppCommand endpoints must never be gated on application state.")
);
}
#[test]
fn access_stage_expr_builds_context_from_resolved_identity() {
let sig: Signature = syn::parse_quote!(fn ping() -> Result<(), ::canic::Error>);
let args = make_args(vec![AccessExprAst::Pred(AccessPredicateAst::Builtin(
BuiltinPredicate::CallerIsController,
))]);
let plan = build_access_plan(EndpointKind::Update, &args, &sig).expect("access plan");
let call = format_ident!("__canic_call");
let stage = access_stage(&plan, &call).to_string();
let compact = stage.split_whitespace().collect::<String>();
assert!(compact.contains("resolve_authenticated_identity("));
assert!(compact.contains("caller:__canic_authenticated_identity.transport_caller"));
assert!(
compact.contains(
"authenticated_caller:__canic_authenticated_identity.authenticated_subject"
)
);
assert!(compact.contains("identity_source:__canic_authenticated_identity.identity_source"));
}
#[test]
fn access_stage_default_guard_marks_identity_source_raw_caller() {
let sig: Signature = syn::parse_quote!(fn ping() -> Result<(), ::canic::Error>);
let args = make_args(Vec::new());
let plan = build_access_plan(EndpointKind::Update, &args, &sig).expect("access plan");
let call = format_ident!("__canic_call");
let stage = access_stage(&plan, &call).to_string();
let compact = stage.split_whitespace().collect::<String>();
assert!(compact.contains("identity_source::canic::__internal::core::access::auth::AuthenticatedIdentitySource::RawCaller")
|| compact.contains("identity_source:::canic::__internal::core::access::auth::AuthenticatedIdentitySource::RawCaller"));
}
}