Update attenuations

packages/core/src/runtime/actor.ts

@@ -3,7 +3,7 @@
 
 import { IdentitySet, Value, embeddedId, is, fromJS, stringify } from '@preserves/core';
 import { Cell, Field, Graph } from './dataflow.js';
-import { Attenuation, runRewrites } from './rewrite.js';
+import { Caveat, runRewrites } from './rewrite.js';
 import { queueTask } from './task.js';
 
 export type AnyValue = Value<Ref>;
@@ -34,15 +34,15 @@ export type Cap = Ref;
 export interface Ref {
     readonly relay: Facet;
     readonly target: Partial<Entity>;
-    readonly attenuation?: Attenuation;
+    readonly attenuation?: Caveat[];
 }
 
 export class RefImpl implements Ref {
     readonly relay: Facet;
     readonly target: Partial<Entity>;
-    readonly attenuation?: Attenuation;
+    readonly attenuation?: Caveat[];
 
-    constructor(relay: Facet, target: Partial<Entity>, attenuation?: Attenuation) {
+    constructor(relay: Facet, target: Partial<Entity>, attenuation?: Caveat[]) {
         this.relay = relay;
         this.target = target;
         this.attenuation = attenuation;

packages/core/src/runtime/rewrite.ts

@@ -8,7 +8,6 @@ import type { SturdyValue } from "../transport/sturdy.js";
 
 import {
     Alts,
-    Attenuation,
     Caveat,
     Lit,
     PAnd,
@@ -155,21 +154,30 @@ export function rewrite(r: Rewrite, v: Assertion): Assertion | null {
 }
 
 export function examineAlternatives(cav: Caveat, v: Assertion): Assertion | null {
-    if (cav._variant === 'Alts') {
-        for (const r of cav.value.alternatives) {
-            const w = rewrite(r, v);
-            if (w !== null) return w;
+    switch (cav._variant) {
+        case "Alts": {
+            for (const r of cav.value.alternatives) {
+                const w = rewrite(r, v);
+                if (w !== null) return w;
+            }
+            return null;
         }
-        return null;
-    } else {
-        return rewrite(cav.value, v);
+        case "Rewrite":
+            return rewrite(cav.value, v);
+        case "Reject":
+            return (match(cav.value.pattern, v) !== null) ? null : v;
+        case "unknown":
+            return null;
+        default:
+            ((_: never) => { throw new Error("bad caveat"); })(cav);
     }
 }
 
-export function runRewrites(a: Attenuation | undefined, v: Assertion): Assertion | null {
+export function runRewrites(a: Caveat[] | undefined, v: Assertion): Assertion | null {
     if (a !== void 0) {
-        for (const stage of a) {
-            const w = examineAlternatives(stage, v);
+        for (let i = a.length - 1; i >= 0; i--) {
+            const caveat = a[i];
+            const w = examineAlternatives(caveat, v);
             if (w === null) return null;
             v = w;
         }
@@ -185,9 +193,9 @@ export function rfilter(... patterns: Pattern[]): Caveat {
     return ps.length === 1 ? Caveat.Rewrite(ps[0]) : Caveat.Alts(Alts(ps));
 }
 
-export function attenuate(ref: Ref, ... a: Attenuation): Ref {
+export function attenuate(ref: Ref, ... a: Caveat[]): Ref {
     if (a.length === 0) return ref;
-    return { ... ref, attenuation: [... a, ... (ref.attenuation ?? [])] };
+    return { ... ref, attenuation: [... (ref.attenuation ?? []), ... a] };
 }
 
 export function forwarder(ref: Ref): { proxy: Ref, revoker: Ref } {

packages/core/src/transport/relay.ts

@@ -7,7 +7,7 @@ import * as IO from '../gen/protocol.js';
 import { wireRefEmbeddedType } from './protocol.js';
 import { queueTask } from '../runtime/task.js';
 import { attenuate } from '../runtime/rewrite.js';
-import { fromAttenuation, WireRef } from '../gen/sturdy.js';
+import { fromCaveat, WireRef } from '../gen/sturdy.js';
 
 export class WireSymbol {
     count = 0;
@@ -264,7 +264,7 @@ export class Relay {
                         if (ar.__attenuations === void 0) {
                             ar.__attenuations = new Dictionary();
                         }
-                        return ar.__attenuations.getOrSet(fromAttenuation(n.attenuation), () =>
+                        return ar.__attenuations.getOrSet(n.attenuation.map(fromCaveat), () =>
                             attenuate(r, ... n.attenuation));
                     }
                 }

packages/core/src/transport/sturdy.ts

@@ -45,17 +45,19 @@ export async function mint(oid: SturdyValue, secretKey: Bytes): Promise<S.Sturdy
     });
 }
 
-export async function attenuate(r: S.SturdyRef, ... a: S.Attenuation): Promise<S.SturdyRef> {
+async function chainMac(key: Bytes | Promise<Bytes>, caveats: S.Caveat[]): Promise<Bytes> {
+    return caveats.reduce(async (key, c) => mac(await key, sturdyEncode(S.fromCaveat(c))), key);
+}
+
+export async function attenuate(r: S.SturdyRef, ... a: S.Caveat[]): Promise<S.SturdyRef> {
     return S.SturdyRef({
         oid: r.oid,
-        caveatChain: [... r.caveatChain, a],
-        sig: await mac(r.sig, sturdyEncode(S.fromAttenuation(a)))
+        caveatChain: [... r.caveatChain, ... a],
+        sig: await chainMac(r.sig, a),
     });
 }
 
 export async function validate(r: S.SturdyRef, secretKey: Bytes): Promise<boolean> {
-    const sig = await r.caveatChain.reduce(
-        async (sig, a) => mac(await sig, sturdyEncode(S.fromAttenuation(a))),
-        mac(secretKey, sturdyEncode(r.oid)));
+    const sig = await chainMac(await mac(secretKey, sturdyEncode(r.oid)), r.caveatChain);
     return is(sig, r.sig);
 }