feat: CBOR TAG (#38)

* feat: CBOR TAG

Author: daviddias

package.json

@@ -40,13 +40,16 @@
     "borc": "^2.0.2",
     "bs58": "^4.0.0",
     "cids": "^0.4.0",
+    "is-circular": "^1.0.1",
     "multihashes": "^0.3.2",
     "multihashing-async": "^0.4.0",
     "traverse": "^0.6.6"
   },
   "devDependencies": {
     "aegir": "^9.4.0",
     "chai": "^3.5.0",
+    "deep-freeze": "0.0.1",
+    "garbage": "0.0.0",
     "ipfs-block": "^0.5.4",
     "pre-commit": "^1.2.2"
   },
@@ -59,4 +62,4 @@
     "npmcdn-to-unpkg-bot <npmcdn-to-unpkg-bot@users.noreply.github.com>",
     "wanderer <mjbecze@gmail.com>"
   ]
-}
+}

src/util.js

@@ -5,39 +5,90 @@ const multihashing = require('multihashing-async')
 const CID = require('cids')
 const waterfall = require('async/waterfall')
 const setImmediate = require('async/setImmediate')
+const isCircular = require('is-circular')
 
 const resolver = require('./resolver')
 
+// https://github.com/ipfs/go-ipfs/issues/3570#issuecomment-273931692
+const CID_CBOR_TAG = 42
+
+function tagCID (cid) {
+  return new cbor.Tagged(CID_CBOR_TAG, cid)
+}
+
+const decoder = new cbor.Decoder({
+  tags: {
+    [CID_CBOR_TAG]: (val) => ({'/': val})
+  }
+})
+
+function replaceCIDbyTAG (dagNode) {
+  if (isCircular(dagNode)) {
+    throw new Error('The object passed has circular references')
+  }
+
+  function transform (obj) {
+    if (!obj || Buffer.isBuffer(obj) || typeof obj === 'string') {
+      return obj
+    }
+
+    if (Array.isArray(obj)) {
+      return obj.map(transform)
+    }
+
+    const keys = Object.keys(obj)
+
+    // only `{'/': 'link'}` are valid
+    if (keys.length === 1 && keys[0] === '/') {
+      // Multiaddr encoding
+      // if (typeof link === 'string' && isMultiaddr(link)) {
+      //  link = new Multiaddr(link).buffer
+      // }
+
+      return tagCID(obj['/'])
+    } else if (keys.length > 0) {
+      // Recursive transform
+      let out = {}
+      keys.forEach((key) => {
+        if (typeof obj[key] === 'object') {
+          out[key] = transform(obj[key])
+        } else {
+          out[key] = obj[key]
+        }
+      })
+      return out
+    } else {
+      return obj
+    }
+  }
+
+  return transform(dagNode)
+}
+
 exports = module.exports
 
 exports.serialize = (dagNode, callback) => {
   let serialized
+
   try {
-    serialized = cbor.encode(dagNode)
+    const dagNodeTagged = replaceCIDbyTAG(dagNode)
+    serialized = cbor.encode(dagNodeTagged)
   } catch (err) {
-    // return is important, otherwise in case of error the execution would continue
-    return setImmediate(() => {
-      callback(err)
-    })
+    return setImmediate(() => callback(err))
   }
-  setImmediate(() => {
-    callback(null, serialized)
-  })
+  setImmediate(() => callback(null, serialized))
 }
 
 exports.deserialize = (data, callback) => {
-  let res
+  let deserialized
+
   try {
-    res = cbor.decodeFirst(data)
+    deserialized = decoder.decodeFirst(data)
   } catch (err) {
-    return setImmediate(() => {
-      callback(err)
-    })
+    return setImmediate(() => callback(err))
   }
 
-  setImmediate(() => {
-    callback(null, res)
-  })
+  setImmediate(() => callback(null, deserialized))
 }
 
 exports.cid = (dagNode, callback) => {

test/util.spec.js

@@ -2,19 +2,35 @@
 'use strict'
 
 const expect = require('chai').expect
+const deepFreeze = require('deep-freeze')
+const garbage = require('garbage')
+const map = require('async/map')
 const dagCBOR = require('../src')
 
 describe('util', () => {
   const obj = {
     someKey: 'someValue',
-    link: { '/': 'aaaaa' }
+    link: { '/': 'aaaaa' },
+    links: [{'/': 1}, {'/': 2}],
+    nested: {
+      hello: 'world',
+      link: { '/': 'mylink' }
+    }
   }
 
   it('.serialize and .deserialize', (done) => {
+    // freeze, to ensure we don't change the source objecdt
+    deepFreeze(obj)
     dagCBOR.util.serialize(obj, (err, serialized) => {
       expect(err).to.not.exist
       expect(Buffer.isBuffer(serialized)).to.be.true
 
+      // Check for the tag 42
+      // d8 = tag, 2a = 42
+      expect(
+        serialized.toString('hex').match(/d82a/g)
+      ).to.have.length(4)
+
       dagCBOR.util.deserialize(serialized, (err, deserialized) => {
         expect(err).to.not.exist
         expect(obj).to.eql(deserialized)
@@ -42,4 +58,29 @@ describe('util', () => {
       done()
     })
   })
+
+  it('serialize and deserialize - garbage', (done) => {
+    const inputs = []
+    for (let i = 0; i < 1000; i++) {
+      inputs.push({in: garbage(100)})
+    }
+
+    map(inputs, (input, cb) => {
+      dagCBOR.util.serialize(input, cb)
+    }, (err, encoded) => {
+      if (err) {
+        return done(err)
+      }
+      map(encoded, (enc, cb) => {
+        dagCBOR.util.deserialize(enc, cb)
+      }, (err, out) => {
+        if (err) {
+          return done(err)
+        }
+
+        expect(inputs).to.be.eql(out)
+        done()
+      })
+    })
+  })
 })