feat: service validation

src/service.js

@@ -1,6 +1,7 @@
 import * as ucan from './ucan-storage.js'
 import { UcanChain } from './ucan-chain.js'
 import { KeyPair } from './keypair.js'
+import { storageSemantics } from './semantics.js'
 
 export class Service {
   /**
@@ -23,24 +24,36 @@ export class Service {
   }
 
   /**
+   * Validates UCAN for capability
+   *
    * @param {string} encodedUcan
-   * @param {import('./types').ValidateOptions} options
+   * @param {import('./types.js').Capability} capability
+   * @returns {Promise<UcanChain>} Returns the root ucan for capability
    */
-  async validate(encodedUcan, options) {
-    const token = await UcanChain.fromToken(encodedUcan, options)
+  async validate(encodedUcan, capability) {
+    const token = await UcanChain.fromToken(encodedUcan, {})
 
     if (token.audience() !== this.did()) {
       throw new Error('Invalid UCAN: Audience does not match this service.')
     }
 
-    return token
+    const origin = token.claim(capability, storageSemantics)
+
+    if (origin.issuer() !== this.did()) {
+      throw new Error('Invalid UCAN: Root issuer does not match this service.')
+    }
+
+    return origin
   }
 
   /**
-   * @param {UcanChain} ucan
+   * @param {string} encodedUcan
    */
-  static caps(ucan) {
-    // return ucans.capabilities(ucan, storageSemantics)
+  async validateFromCaps(encodedUcan) {
+    const token = await UcanChain.fromToken(encodedUcan, {})
+    const caps = token.caps(storageSemantics)
+
+    return caps[0]
   }
 
   did() {

src/ucan-chain.js

@@ -5,7 +5,7 @@ import * as ucan from './index.js'
  * @param {import('./types').CapabilitySemantics<A>} semantics
  * @param {UcanChain} ucan
  */
-function* findValidCaps(semantics, ucan) {
+export function* findValidCaps(semantics, ucan) {
   const caps = ucan.capabilities()
   const parentCaps = []
 
@@ -73,7 +73,7 @@ function canDelegate(ucan, capParsed, semantics) {
  * @param {UcanChain} ucan
  * @param {A} capParsed
  * @param {import('./types').CapabilitySemantics<A>} semantics
- * @returns {UcanChain | undefined}
+ * @returns {UcanChain}
  */
 function findRoot(ucan, capParsed, semantics) {
   const proofs = ucan.proofs()
@@ -158,9 +158,8 @@ export class UcanChain {
     const validCaps = []
     for (const cap of findValidCaps(semantics, this)) {
       try {
-        if (findRoot(this, cap, semantics)) {
-          validCaps.push(cap)
-        }
+        const root = findRoot(this, cap, semantics)
+        validCaps.push({ root, cap })
       } catch {}
     }