feat: support exporting nodes encoded with the identity hash (#27)

* feat: support exporting nodes encoded with the identity hash

We can encode small amounts of data inside CIDs so we should be able
to export them too.

* chore: update require

Author: achingbrain

package.json

@@ -49,7 +49,6 @@
     "ipld-in-memory": "^3.0.0",
     "ipfs-unixfs-importer": "^0.42.0",
     "multicodec": "^1.0.0",
-    "multihashes": "^0.4.14",
     "nyc": "^15.0.0",
     "sinon": "^8.0.4"
   },

src/resolvers/identity.js

@@ -0,0 +1,38 @@
+'use strict'
+
+const errCode = require('err-code')
+const extractDataFromBlock = require('../utils/extract-data-from-block')
+const validateOffsetAndLength = require('../utils/validate-offset-and-length')
+const mh = require('multihashing-async').multihash
+
+const rawContent = (node) => {
+  return function * (options = {}) {
+    const {
+      offset,
+      length
+    } = validateOffsetAndLength(node.length, options.offset, options.length)
+
+    yield extractDataFromBlock(node, 0, offset, offset + length)
+  }
+}
+
+const resolve = async (cid, name, path, toResolve, resolve, depth, ipld) => {
+  if (toResolve.length) {
+    throw errCode(new Error(`No link named ${path} found in raw node ${cid.toBaseEncodedString()}`), 'ERR_NOT_FOUND')
+  }
+
+  const buf = await mh.decode(cid.multihash)
+
+  return {
+    entry: {
+      name,
+      path,
+      cid,
+      node: buf,
+      content: rawContent(buf.digest),
+      depth
+    }
+  }
+}
+
+module.exports = resolve

src/resolvers/index.js

@@ -5,7 +5,8 @@ const errCode = require('err-code')
 const resolvers = {
   'dag-pb': require('./unixfs-v1'),
   raw: require('./raw'),
-  'dag-cbor': require('./dag-cbor')
+  'dag-cbor': require('./dag-cbor'),
+  identity: require('./identity')
 }
 
 const resolve = (cid, name, path, toResolve, depth, ipld) => {

test/exporter-sharded.spec.js

@@ -7,7 +7,7 @@ const expect = chai.expect
 const IPLD = require('ipld')
 const inMemory = require('ipld-in-memory')
 const UnixFS = require('ipfs-unixfs')
-const mh = require('multihashes')
+const mh = require('multihashing-async').multihash
 const mc = require('multicodec')
 const all = require('async-iterator-all')
 const last = require('async-iterator-last')
@@ -184,15 +184,15 @@ describe('exporter sharded', function () {
   it('exports a file from a sharded directory inside a regular directory inside a sharded directory', async () => {
     const dirCid = await createShard(15)
 
-    const node = new DAGNode(new UnixFS('directory').marshal(), [
+    const node = new DAGNode(new UnixFS({ type: 'directory' }).marshal(), [
       new DAGLink('shard', 5, dirCid)
     ])
     const nodeCid = await ipld.put(node, mc.DAG_PB, {
       cidVersion: 0,
       hashAlg: mh.names['sha2-256']
     })
 
-    const shardNode = new DAGNode(new UnixFS('hamt-sharded-directory').marshal(), [
+    const shardNode = new DAGNode(new UnixFS({ type: 'hamt-sharded-directory' }).marshal(), [
       new DAGLink('75normal-dir', 5, nodeCid)
     ])
     const shardNodeCid = await ipld.put(shardNode, mc.DAG_PB, {

test/exporter.spec.js

@@ -12,7 +12,7 @@ const {
   DAGNode,
   DAGLink
 } = require('ipld-dag-pb')
-const mh = require('multihashes')
+const mh = require('multihashing-async').multihash
 const mc = require('multicodec')
 const exporter = require('../src')
 const importer = require('ipfs-unixfs-importer')
@@ -38,7 +38,10 @@ describe('exporter', () => {
     options.content = options.content || Buffer.from([0x01, 0x02, 0x03])
     options.links = options.links || []
 
-    const file = new UnixFS(options.type, options.content)
+    const file = new UnixFS({
+      type: options.type,
+      data: options.content
+    })
 
     const node = new DAGNode(file.marshal(), options.links)
     const cid = await ipld.put(node, mc.DAG_PB, {
@@ -190,7 +193,10 @@ describe('exporter', () => {
 
   it('exports a small file with links', async () => {
     const content = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
-    const chunk1 = new UnixFS('raw', content.slice(0, 5))
+    const chunk1 = new UnixFS({
+      type: 'raw',
+      data: content.slice(0, 5)
+    })
     const chunkNode1 = new DAGNode(chunk1.marshal())
     const chunkCid1 = await ipld.put(chunkNode1, mc.DAG_PB, {
       cidVersion: 0,
@@ -204,7 +210,9 @@ describe('exporter', () => {
       hashAlg: mh.names['sha2-256']
     })
 
-    const file = new UnixFS('file')
+    const file = new UnixFS({
+      type: 'file'
+    })
     file.addBlockSize(5)
     file.addBlockSize(5)
 
@@ -830,7 +838,9 @@ describe('exporter', () => {
       foo: 'bar'
     }, mc.DAG_CBOR)
 
-    const file = new UnixFS('file')
+    const file = new UnixFS({
+      type: 'file'
+    })
     file.addBlockSize(100)
 
     const cid = await ipld.put(new DAGNode(file.marshal(), [
@@ -891,4 +901,56 @@ describe('exporter', () => {
     expect(exported[4].name).to.equal('qux.txt')
     expect(exported[4].path).to.equal(`${dirCid}/qux.txt`)
   })
+
+  it('exports a CID encoded with the identity hash', async () => {
+    const data = Buffer.from('hello world')
+    const hash = mh.encode(data, 'identity')
+    const cid = new CID(1, 'identity', hash)
+
+    const exported = await exporter(cid, ipld)
+    const result = Buffer.concat(await all(exported.content()))
+
+    expect(result).to.deep.equal(data)
+    expect(result.toString('utf8')).to.equal('hello world')
+  })
+
+  it('exports a CID encoded with the identity hash with an offset', async () => {
+    const data = Buffer.from('hello world')
+    const hash = mh.encode(data, 'identity')
+    const cid = new CID(1, 'identity', hash)
+
+    const exported = await exporter(cid, ipld)
+    const result = Buffer.concat(await all(exported.content({
+      offset: 1
+    })))
+
+    expect(result.toString('utf8')).to.equal('ello world')
+  })
+
+  it('exports a CID encoded with the identity hash with a length', async () => {
+    const data = Buffer.from('hello world')
+    const hash = mh.encode(data, 'identity')
+    const cid = new CID(1, 'identity', hash)
+
+    const exported = await exporter(cid, ipld)
+    const result = Buffer.concat(await all(exported.content({
+      length: 1
+    })))
+
+    expect(result.toString('utf8')).to.equal('h')
+  })
+
+  it('exports a CID encoded with the identity hash with an offset and a length', async () => {
+    const data = Buffer.from('hello world')
+    const hash = mh.encode(data, 'identity')
+    const cid = new CID(1, 'identity', hash)
+
+    const exported = await exporter(cid, ipld)
+    const result = Buffer.concat(await all(exported.content({
+      offset: 3,
+      length: 1
+    })))
+
+    expect(result.toString('utf8')).to.equal('l')
+  })
 })