wrapper: fix callsscripts decoding (#283)

See schema for callsscript data: https://github.com/aragon/aragonOS/blob/dev/contracts/evmscript/executors/CallsScript.sol#L28.

Fixes #260.

packages/aragon-wrapper/src/evmscript/index.test.js

@@ -8,6 +8,9 @@ test('encodeCallScript', (t) => {
   }, {
     to: '0xbeefbeef03c7e5a1c29e0aa675f8e16aee0a5fad',
     data: '0xbeef'
+  }, {
+    to: '0xbaaabaaa03c7e5a1c29e0aa675f8e16aee0a5fad',
+    data: '0x'
   }])
 
   t.is(
@@ -45,4 +48,14 @@ test('encodeCallScript', (t) => {
     'beef',
     'sixth part of callscript should be data for tx 2'
   )
+  t.is(
+    callScript.slice(114, 154),
+    'baaabaaa03c7e5a1c29e0aa675f8e16aee0a5fad',
+    'seventh part of callscript should be address for tx 3'
+  )
+  t.is(
+    callScript.slice(154, 162),
+    '00000000',
+    'eigth part of callscript should be data length for tx 3'
+  )
 })

packages/aragon-wrapper/src/index.js

@@ -1212,53 +1212,6 @@ export default class Aragon {
     ).toPromise()
   }
 
-  /**
-   * Decodes an EVM callscript and returns the transaction path it describes.
-   *
-   * @param  {string} script
-   * @return {Array<Object>} An array of Ethereum transactions that describe each step in the path
-   */
-  decodeTransactionPath (script) {
-    // TODO: Support callscripts with multiple transactions in one (i.e. one ID, multiple destinations)
-    function decodePathSegment (script) {
-      // Remove script identifier
-      script = script.substr(10)
-
-      // Get address
-      const destination = `0x${script.substr(0, 40)}`
-      script = script.substr(40)
-
-      // Get data
-      const dataLength = parseInt(`0x${script.substr(0, 8)}`) * 2
-      script = script.substr(8)
-      const data = `0x${script.substr(0, dataLength)}`
-      script = script.substr(dataLength)
-
-      return {
-        to: destination,
-        data
-      }
-    }
-
-    let scriptId = script.substr(0, 10)
-    if (scriptId !== CALLSCRIPT_ID) {
-      throw new Error(`Unknown script ID ${scriptId}`)
-    }
-
-    let path = []
-    while (script.startsWith(CALLSCRIPT_ID)) {
-      const segment = decodePathSegment(script)
-
-      // Set script
-      script = segment.data
-
-      // Push segment
-      path.push(segment)
-    }
-
-    return path
-  }
-
   /**
    * Calculate the transaction path for a transaction to `destination`
    * that invokes `methodName` with `params`.
@@ -1352,6 +1305,51 @@ export default class Aragon {
     }
   }
 
+  /**
+   * Decodes an EVM callscript and returns the transaction path it describes.
+   *
+   * @param  {string} script
+   * @return {Array<Object>} An array of Ethereum transactions that describe each step in the path
+   */
+  decodeTransactionPath (script) {
+    function decodePathSegment (script) {
+      // Get address
+      const to = `0x${script.substring(0, 40)}`
+      script = script.substring(40)
+
+      // Get data
+      const dataLength = parseInt(`0x${script.substring(0, 8)}`, 16) * 2
+      script = script.substring(8)
+      const data = `0x${script.substring(0, dataLength)}`
+
+      // Return rest of script for processing
+      script = script.substring(dataLength)
+
+      return {
+        segment: {
+          data,
+          to
+        },
+        scriptLeft: script
+      }
+    }
+
+    // Get script identifier (0x prefix + bytes4)
+    const scriptId = script.substring(0, 10)
+    if (scriptId !== CALLSCRIPT_ID) {
+      throw new Error(`Unknown script ID ${scriptId}`)
+    }
+
+    const segments = []
+    let scriptData = script.substring(10)
+    while (scriptData.length > 0) {
+      const { segment, scriptLeft } = decodePathSegment(scriptData)
+      segments.push(segment)
+      scriptData = scriptLeft
+    }
+    return segments
+  }
+
   /**
    * Use radspec to create a human-readable description for each transaction in the given `path`
    *
@@ -1369,9 +1367,9 @@ export default class Aragon {
       if (!app.functions) return step
 
       // Find the method
-      const methodId = step.data.substr(2, 8)
+      const methodId = step.data.substring(2, 10)
       const method = app.functions.find(
-        (method) => keccak256(method.sig).substr(0, 8) === methodId
+        (method) => keccak256(method.sig).substring(0, 8) === methodId
       )
 
       // Method does not exist in artifact

packages/aragon-wrapper/src/index.test.js

@@ -4,6 +4,7 @@ import proxyquire from 'proxyquire'
 import { Subject, empty, of, from } from 'rxjs'
 import { first } from 'rxjs/operators'
 import { getKernelNamespace } from './core/aragonOS'
+import { encodeCallScript } from './evmscript'
 import AsyncRequestCache from './utils/AsyncRequestCache'
 
 // soliditySha3('app')
@@ -1300,3 +1301,57 @@ test('should throw if no ABI is found, when calculating the transaction path', a
        */
     })
 })
+
+test('should be able to decode an evm call script with a single transaction', async (t) => {
+  const { Aragon } = t.context
+
+  t.plan(1)
+  // arrange
+  const instance = new Aragon()
+  const script = encodeCallScript([{
+    to: '0xcafe1a77e84698c83ca8931f54a755176ef75f2c',
+    data: '0xcafe'
+  }])
+  // act
+  const decodedScript = instance.decodeTransactionPath(script)
+  // assert
+  t.deepEqual(decodedScript, [
+    {
+      data: '0xcafe',
+      to: '0xcafe1a77e84698c83ca8931f54a755176ef75f2c'
+    }
+  ])
+})
+
+test('should be able to decode an evm call script with multiple transactions', async (t) => {
+  const { Aragon } = t.context
+
+  t.plan(1)
+  // arrange
+  const instance = new Aragon()
+  const script = encodeCallScript([{
+    to: '0xcafe1a77e84698c83ca8931f54a755176ef75f2c',
+    data: '0xcafe'
+  }, {
+    to: '0xbeefbeef03c7e5a1c29e0aa675f8e16aee0a5fad',
+    data: '0xbeef'
+  }, {
+    to: '0xbaaabaaa03c7e5a1c29e0aa675f8e16aee0a5fad',
+    data: '0x'
+  }])
+  // act
+  const decodedScript = instance.decodeTransactionPath(script)
+  // assert
+  t.deepEqual(decodedScript, [
+    {
+      to: '0xcafe1a77e84698c83ca8931f54a755176ef75f2c',
+      data: '0xcafe'
+    }, {
+      to: '0xbeefbeef03c7e5a1c29e0aa675f8e16aee0a5fad',
+      data: '0xbeef'
+    }, {
+      to: '0xbaaabaaa03c7e5a1c29e0aa675f8e16aee0a5fad',
+      data: '0x'
+    }
+  ])
+})