From e8f983ec85e43cebbc3f28800af3752424ca1d5d Mon Sep 17 00:00:00 2001
From: Elad <theman@elad.im>
Date: Thu, 7 Mar 2019 20:27:13 +0700
Subject: [PATCH] wip

---
 contracts/ens/ens.go      | 46 ++++++++++++++++++++++++++++++++++++++
 contracts/ens/ens_test.go | 47 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+)

diff --git a/contracts/ens/ens.go b/contracts/ens/ens.go
index 0d7449ebaa..8c356e6be2 100644
--- a/contracts/ens/ens.go
+++ b/contracts/ens/ens.go
@@ -23,6 +23,8 @@ package ens
 
 import (
 	"encoding/binary"
+	"errors"
+	"fmt"
 	"strings"
 
 	mh "github.com/multiformats/go-multihash"
@@ -285,6 +287,50 @@ func decodeMultiCodec(b []byte) (common.Hash, error) {
 
 }
 
+func manualDecode(buf []byte) (common.Hash, error) {
+	if len(buf) < 2 {
+		return common.Hash{}, errors.New("buffer too short")
+	}
+
+	storageSys, n := binary.Uvarint(buf)
+	if storageSys != 0xe3 && storageSys != 0xe4 {
+		return common.Hash{}, errors.New("unknown storage system")
+	}
+	buf = buf[n:]
+	vers, n := binary.Uvarint(buf)
+
+	if vers != 1 {
+		return common.Hash{}, fmt.Errorf("expected 1 as the cid version number, got: %d", vers)
+	}
+
+	buf = buf[n:]
+	ctype, n := binary.Uvarint(buf)
+
+	if ctype != 0x99 {
+		return common.Hash{}, errors.New("unknown content type")
+	}
+	buf = buf[n:]
+	hashType, n := binary.Uvarint(buf)
+
+	if hashType != 0x1b {
+		return common.Hash{}, errors.New("unknown multihash type")
+	}
+
+	buf = buf[n:]
+	hashLen, n := binary.Uvarint(buf)
+
+	if hashLen != 32 {
+		return common.Hash{}, errors.New("odd hash length, swarm expects 32 bytes")
+	}
+	buf = buf[n:]
+
+	if len(buf) != int(hashLen) {
+		return common.Hash{}, errors.New("hash length mismatch")
+	}
+
+	return common.BytesToHash(buf), nil
+}
+
 // encodeCid encodes a swarm hash into an IPLD CID
 func encodeCid(h common.Hash) (cid.Cid, error) {
 	b := []byte{0x1b, 0x20}     //0x1b = keccak256 (should be changed to bmt), 0x20 = 32 bytes hash length
diff --git a/contracts/ens/ens_test.go b/contracts/ens/ens_test.go
index 8bd08ec0ee..17600a05ac 100644
--- a/contracts/ens/ens_test.go
+++ b/contracts/ens/ens_test.go
@@ -18,6 +18,8 @@ package ens
 
 import (
 	"bytes"
+	"encoding/binary"
+	"encoding/hex"
 	"fmt"
 	"math/big"
 	"testing"
@@ -125,6 +127,51 @@ func TestENS(t *testing.T) {
 	}
 	t.Fatal("todo: try to set old contract with new multicodec stuff and assert fail, set new contract with multicodec stuff, encode, decode and assert returns correct hash")
 }
+func TestManuelCidDecode(t *testing.T) {
+	// call cid encode method with hash. expect byte slice returned, compare according to spec
+	bb := []byte{}
+	buf := make([]byte, binary.MaxVarintLen64)
+
+	for _, v := range []byte{0xe4, 0x01, 0x99, 0x1b, 0x20} {
+		n := binary.PutUvarint(buf, uint64(v))
+		bb = append(bb, buf[:n]...)
+	}
+	h := common.HexToHash("29f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f")
+	bb = append(bb, h[:]...)
+	str := hex.EncodeToString(bb)
+	fmt.Println(str)
+	decodedHash, e := manualDecode(bb)
+	if e != nil {
+		t.Fatal(e)
+	}
+
+	if !bytes.Equal(decodedHash[:], h[:]) {
+		t.Fatal("hashes not equal")
+	}
+	/* from the EIP documentation
+	   storage system: Swarm (0xe4)
+	   CID version: 1 (0x01)
+	   content type: swarm-manifest (0x??)
+	   hash function: keccak-256 (0x1B)
+	   hash length: 32 bytes (0x20)
+	   hash: 29f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f
+	*/
+
+}
+
+func TestManuelCidEncode(t *testing.T) {
+	// call cid encode method with hash. expect byte slice returned, compare according to spec
+
+	/* from the EIP documentation
+	   storage system: Swarm (0xe4)
+	   CID version: 1 (0x01)
+	   content type: swarm-manifest (0x??)
+	   hash function: keccak-256 (0x1B)
+	   hash length: 32 bytes (0x20)
+	   hash: 29f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f
+	*/
+
+}
 
 func TestCIDSanity(t *testing.T) {
 	hashStr := "d1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162"