Proof of concept: parse head advertisement

cid-vs-multihash.js

@@ -0,0 +1,25 @@
+import { CID } from 'multiformats/cid'
+import * as multihash from 'multiformats/hashes/digest'
+
+/*
+HUMAN READABLE CID
+base32    - cidv1   - raw        - (sha2-256 : 256 : FAE8D07F50DBBCD3FDD65610ADCD6C3DF2171B31AE97041B1E222506E78DFD94)
+MULTIBASE - VERSION - MULTICODEC - MULTIHASH (NAME : SIZE : DIGEST IN HEX)
+*/
+const MY_CID = 'bafkreih25dih6ug3xtj73vswccw423b56ilrwmnos4cbwhrceudopdp5sq'
+console.log('CID string', MY_CID)
+
+// Found via https://cid.contact/cid/bafkreih25dih6ug3xtj73vswccw423b56ilrwmnos4cbwhrceudopdp5sq
+const MULTIHASH = 'EiD66NB/UNu80/3WVhCtzWw98hcbMa6XBBseIiUG5439lA=='
+console.log('IPNI Multihash (base64)', MULTIHASH)
+console.log('IPNI multihash (hex)', Buffer.from(MULTIHASH, 'base64').toString('hex'))
+
+const cid = CID.parse(MY_CID)
+console.log('CID multihash (hex) ', Buffer.from(cid.multihash.bytes).toString('hex'))
+console.log('CID codec', '0x' + cid.code.toString(16))
+
+const cid2 = CID.create(cid.version, 0x70 /* dag-pb */, cid.multihash)
+console.log('dag-pb CID', cid2)
+
+console.log('CID FROM MULTIHASH', CID.create(1, 0x55 /* raw */, multihash.decode(Buffer.from(MULTIHASH, 'base64'))))
+console.log('ORIGINAL CID      ', cid)

package.json

@@ -16,5 +16,10 @@
   "bugs": {
     "url": "https://github.com/filecoin-station/piece-indexer/issues"
   },
-  "homepage": "https://github.com/filecoin-station/piece-indexer#readme"
+  "homepage": "https://github.com/filecoin-station/piece-indexer#readme",
+  "dependencies": {
+    "@ipld/dag-cbor": "^9.2.1",
+    "@multiformats/multiaddr-to-uri": "^10.1.0",
+    "multiformats": "^13.1.3"
+  }
 }

parse-metada.js

@@ -0,0 +1,31 @@
+import { varint } from 'multiformats'
+import * as cbor from '@ipld/dag-cbor'
+
+// console.log(parseMetadata(
+//   'kBKjaFBpZWNlQ0lE2CpYKAABgeIDkiAgieDL6/pbxDBAJtdZ19ZsvGh1NE77nBxbFwesoG1S/jJsVmVyaWZpZWREZWFs9W1GYXN0UmV0cmlldmFs9Q'
+// ))
+
+export function parseMetadata (meta) {
+  const bytes = Buffer.from(meta, 'base64')
+  const [protocolCode, nextOffset] = varint.decode(bytes)
+
+  const protocol = {
+    0x900: 'bitswap',
+    0x910: 'graphsync',
+    0x0920: 'http'
+  }[protocolCode] ?? '0x' + protocolCode.toString(16)
+
+  if (protocol === 'graphsync') {
+    // console.log(bytes.subarray(nextOffset).toString('hex'))
+
+    /** @type {{
+    PieceCID: import('multiformats/cid').CID,
+    VerifiedDeal: boolean,
+    FastRetrieval: boolean
+    }} */
+    const deal = cbor.decode(bytes.subarray(nextOffset))
+    return { protocol, deal }
+  } else {
+    return { protocol }
+  }
+}