feat(multiformats): add Cid extensions

README.md

@@ -148,6 +148,7 @@ Extend `MultiFormats`:
 | `MultiHash`    | `-d:libp2p_multihash_exts`                 | `const HashExts = []`         |
 | `MultiAddress` | `-d:libp2p_multiaddress_exts`              | `const AddressExts = []`      |
 | `MultiBase`    | `-d:libp2p_multibase_exts`                 | `const BaseExts = []`         |
+| `ContentIds`   | `-d:libp2p_contentids_exts`                | `const ContentIdsExts = []`   |
 
 For example, a file called `multihash_exts.nim` could be created and contain `MultiHash` extensions:
 ```nim

libp2p.nimble

@@ -53,7 +53,8 @@ task testmultiformatexts, "Run multiformat extensions tests":
     "-d:libp2p_multicodec_exts=../tests/multiformat_exts/multicodec_exts.nim " &
     "-d:libp2p_multiaddress_exts=../tests/multiformat_exts/multiaddress_exts.nim " &
     "-d:libp2p_multihash_exts=../tests/multiformat_exts/multihash_exts.nim " &
-    "-d:libp2p_multibase_exts=../tests/multiformat_exts/multibase_exts.nim "
+    "-d:libp2p_multibase_exts=../tests/multiformat_exts/multibase_exts.nim " &
+    "-d:libp2p_contentids_exts=../tests/multiformat_exts/contentids_exts.nim "
   runTest("multiformat_exts/testmultiformat_exts", opts)
 
 task testnative, "Runs libp2p native tests":

libp2p/cid.nim

@@ -13,7 +13,7 @@
 {.used.}
 
 import tables, hashes
-import multibase, multicodec, multihash, vbuffer, varint, results
+import multibase, multicodec, multihash, vbuffer, varint, results, utility
 import stew/base58
 import ./utils/sequninit
 
@@ -38,6 +38,8 @@ type
     hpos*: int
     data*: VBuffer
 
+const libp2p_contentids_exts* {.strdefine.} = ""
+
 const ContentIdsList = [
   multiCodec("raw"),
   multiCodec("dag-pb"),
@@ -69,11 +71,21 @@ const ContentIdsList = [
   multiCodec("ed25519-pub"),
 ]
 
-proc initCidCodeTable(): Table[int, MultiCodec] {.compileTime.} =
-  for item in ContentIdsList:
-    result[int(item)] = item
+proc initCidCodeTable(
+    codecs: openArray[MultiCodec]
+): Table[int, MultiCodec] {.compileTime.} =
+  var res: Table[int, MultiCodec]
+
+  for codec in codecs:
+    res[codec.int] = codec
+
+  return res
 
-const CodeContentIds = initCidCodeTable()
+when libp2p_contentids_exts != "":
+  includeFile(libp2p_contentids_exts)
+  const CodeContentIds = initCidCodeTable(@ContentIdsList & @ContentIdsExts)
+else:
+  const CodeContentIds = initCidCodeTable(@ContentIdsList)
 
 template orError*(exp: untyped, err: untyped): untyped =
   exp.mapErr do(_: auto) -> auto:

tests/multiformat_exts/contentids_exts.nim

@@ -0,0 +1 @@
+const ContentIdsExts = [multiCodec("codec_mc1"), multiCodec("codec_mc2")]

tests/multiformat_exts/testcontentids_exts.nim

@@ -0,0 +1,46 @@
+{.used.}
+
+# Nim-Libp2p
+# Copyright (c) 2023 Status Research & Development GmbH
+# Licensed under either of
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+# at your option.
+# This file may not be copied, modified, or distributed except according to
+# those terms.
+
+import unittest2
+import ../../libp2p/cid
+import ../../libp2p/multicodec
+import ../../libp2p/multihash
+
+suite "ContentId extensions":
+  test "extended contentids correctly hash data":
+    var bmsg = cast[seq[byte]]("hello")
+    var cid0 = Cid
+      .init(CIDv1, multiCodec("codec_mc1"), MultiHash.digest("codec_mc2", bmsg).get())
+      .tryGet()
+    var cid1 = Cid
+      .init(CIDv1, multiCodec("codec_mc2"), MultiHash.digest("codec_mc1", bmsg).get())
+      .tryGet()
+    check:
+      cid0.hex == "0181FE0382FE030668656C6C6F00"
+      cid1.hex == "0182FE0381FE030568656C6C6F"
+      $cid0 == "zZ9hvSmq764xLht1dRH"
+      $cid1 == "z8JZsv4DR12xsE7Fn6"
+
+  test "can initialise extended Cids":
+    let expected1 = "zZ9hvSmq764xLht1dRH"
+    let expected2 = "z8JZsv4DR12xsE7Fn6"
+    let cid1 = Cid.init(expected1).get
+    let cid2 = Cid.init(expected2).get
+
+    check:
+      $cid1 == expected1
+      cid1.version == CIDv1
+      cid1.contentType.get == multiCodec("codec_mc1")
+      cid1.mhash.get.mcodec == multiCodec("codec_mc2")
+      $cid2 == expected2
+      cid2.version == CIDv1
+      cid2.contentType.get == multiCodec("codec_mc2")
+      cid2.mhash.get.mcodec == multiCodec("codec_mc1")

tests/multiformat_exts/testmultiformat_exts.nim

@@ -1,2 +1,3 @@
 import
-  testmulticodec_exts, testmultihash_exts, testmultiaddress_exts, testmultibase_exts
+  testmulticodec_exts, testmultihash_exts, testmultiaddress_exts, testmultibase_exts,
+  testcontentids_exts