contracts, swarm: implement EIP-1577

cmd/swarm/hash.go

@@ -19,10 +19,13 @@ package main
 
 import (
 	"context"
+	"encoding/hex"
 	"fmt"
 	"os"
 
 	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/contracts/ens"
 	"github.com/ethereum/go-ethereum/swarm/storage"
 	"gopkg.in/urfave/cli.v1"
 )
@@ -34,7 +37,33 @@ var hashCommand = cli.Command{
 	Usage:              "print the swarm hash of a file or directory",
 	ArgsUsage:          "<file>",
 	Description:        "Prints the swarm hash of file or directory",
-}
+	Subcommands: []cli.Command{
+		{
+			CustomHelpTemplate: helpTemplate,
+			Name:               "ens",
+			Usage:              "converts a swarm hash to an ens EIP1577 compatible CIDv1 hash",
+			ArgsUsage:          "<ref>",
+			Description:        "",
+			Subcommands: []cli.Command{
+				{
+					Action:             encodeEipHash,
+					CustomHelpTemplate: helpTemplate,
+					Name:               "contenthash",
+					Usage:              "converts a swarm hash to an ens EIP1577 compatible CIDv1 hash",
+					ArgsUsage:          "<ref>",
+					Description:        "",
+				},
+				{
+					Action:             ensNodeHash,
+					CustomHelpTemplate: helpTemplate,
+					Name:               "node",
+					Usage:              "converts an ens name to an ENS node hash",
+					ArgsUsage:          "<ref>",
+					Description:        "",
+				},
+			},
+		},
+	}}
 
 func hash(ctx *cli.Context) {
 	args := ctx.Args()
@@ -56,3 +85,31 @@ func hash(ctx *cli.Context) {
 		fmt.Printf("%v\n", addr)
 	}
 }
+func ensNodeHash(ctx *cli.Context) {
+	args := ctx.Args()
+	if len(args) < 1 {
+		utils.Fatalf("Usage: swarm hash ens node <ens name>")
+	}
+	ensName := args[0]
+
+	hash := ens.EnsNode(ensName)
+
+	stringHex := hex.EncodeToString(hash[:])
+	fmt.Println(stringHex)
+}
+func encodeEipHash(ctx *cli.Context) {
+	args := ctx.Args()
+	if len(args) < 1 {
+		utils.Fatalf("Usage: swarm hash ens <swarm hash>")
+	}
+	swarmHash := args[0]
+
+	hash := common.HexToHash(swarmHash)
+	ensHash, err := ens.EncodeSwarmHash(hash)
+	if err != nil {
+		utils.Fatalf("error converting swarm hash", err)
+	}
+
+	stringHex := hex.EncodeToString(ensHash)
+	fmt.Println(stringHex)
+}

contracts/ens/README.md

@@ -18,3 +18,13 @@ The go bindings for ENS contracts are generated using `abigen` via the go genera
 ```shell
 go generate ./contracts/ens
 ```
+
+## Fallback contract support
+
+In order to better support content resolution on different service providers (such as Swarm and IPFS), [EIP-1577](https://eips.ethereum.org/EIPS/eip-1577)
+was introduced and with it changes that allow applications to know _where_ content hashes are stored (i.e. if the
+requested hash resides on Swarm or IPFS).
+
+The code under `contracts/ens/contract` reflects the new Public Resolver changes and the code under `fallback_contract` allows
+us to support the old contract resolution in cases where the ENS name owner did not update her Resolver contract, until the migration
+period ends (date arbitrarily set to June 1st, 2019).

contracts/ens/cid.go

@@ -0,0 +1,120 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package ens
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+const (
+	cidv1 = 0x1
+
+	nsIpfs  = 0xe3
+	nsSwarm = 0xe4
+
+	swarmTypecode = 0xfa //swarm manifest, see https://github.com/multiformats/multicodec/blob/master/table.csv
+	swarmHashtype = 0xd6 // BMT, see https://github.com/multiformats/multicodec/blob/master/table.csv
+
+	hashLength = 32
+)
+
+// deocodeEIP1577ContentHash decodes a chain-stored content hash from an ENS record according to EIP-1577
+// a successful decode will result the different parts of the content hash in accordance to the CID spec
+// Note: only CIDv1 is supported
+func decodeEIP1577ContentHash(buf []byte) (storageNs, contentType, hashType, hashLength uint64, hash []byte, err error) {
+	if len(buf) < 10 {
+		return 0, 0, 0, 0, nil, errors.New("buffer too short")
+	}
+
+	storageNs, n := binary.Uvarint(buf)
+
+	buf = buf[n:]
+	vers, n := binary.Uvarint(buf)
+
+	if vers != 1 {
+		return 0, 0, 0, 0, nil, fmt.Errorf("expected cid v1, got: %d", vers)
+	}
+	buf = buf[n:]
+	contentType, n = binary.Uvarint(buf)
+
+	buf = buf[n:]
+	hashType, n = binary.Uvarint(buf)
+
+	buf = buf[n:]
+	hashLength, n = binary.Uvarint(buf)
+
+	hash = buf[n:]
+
+	if len(hash) != int(hashLength) {
+		return 0, 0, 0, 0, nil, errors.New("hash length mismatch")
+	}
+	return storageNs, contentType, hashType, hashLength, hash, nil
+}
+
+func extractContentHash(buf []byte) (common.Hash, error) {
+	storageNs, contentType, hashType, hashLength, hashBytes, err := decodeEIP1577ContentHash(buf)
+
+	if err != nil {
+		return common.Hash{}, err
+	}
+
+	if storageNs != nsSwarm {
+		return common.Hash{}, errors.New("unknown storage system")
+	}
+
+	if contentType != swarmTypecode {
+		return common.Hash{}, errors.New("unknown content type")
+	}
+
+	if hashType != swarmHashtype {
+		return common.Hash{}, errors.New("unknown multihash type")
+	}
+
+	if hashLength != hashLength {
+		return common.Hash{}, errors.New("odd hash length, swarm expects 32 bytes")
+	}
+
+	if len(hashBytes) != int(hashLength) {
+		return common.Hash{}, errors.New("hash length mismatch")
+	}
+
+	return common.BytesToHash(buf), nil
+}
+
+func EncodeSwarmHash(hash common.Hash) ([]byte, error) {
+	var cidBytes []byte
+	var headerBytes = []byte{
+		nsSwarm,       //swarm namespace
+		cidv1,         // CIDv1
+		swarmTypecode, // swarm hash
+		swarmHashtype, // swarm bmt hash
+		hashLength,    //hash length. 32 bytes
+	}
+
+	varintbuf := make([]byte, binary.MaxVarintLen64)
+	for _, v := range headerBytes {
+		n := binary.PutUvarint(varintbuf, uint64(v))
+		cidBytes = append(cidBytes, varintbuf[:n]...)
+	}
+
+	cidBytes = append(cidBytes, hash[:]...)
+	return cidBytes, nil
+}

contracts/ens/cid_test.go

@@ -0,0 +1,148 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package ens
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+// Tests for the decoding of the example ENS
+func TestEIPSpecCidDecode(t *testing.T) {
+	const (
+		eipSpecHash = "e3010170122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f"
+		eipHash     = "29f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f"
+		dagPb       = 0x70
+		sha2256     = 0x12
+	)
+	b, err := hex.DecodeString(eipSpecHash)
+	if err != nil {
+		t.Fatal(err)
+	}
+	hashBytes, err := hex.DecodeString(eipHash)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	storageNs, contentType, hashType, hashLength, decodedHashBytes, err := decodeEIP1577ContentHash(b)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+	if storageNs != nsIpfs {
+		t.Fatal("wrong ns")
+	}
+	if contentType != dagPb {
+		t.Fatal("should be ipfs typecode")
+	}
+	if hashType != sha2256 {
+		t.Fatal("should be sha2-256")
+	}
+	if hashLength != 32 {
+		t.Fatal("should be 32")
+	}
+	if !bytes.Equal(hashBytes, decodedHashBytes) {
+		t.Fatal("should be equal")
+	}
+
+}
+func TestManualCidDecode(t *testing.T) {
+	// call cid encode method with hash. expect byte slice returned, compare according to spec
+
+	for _, v := range []struct {
+		name        string
+		headerBytes []byte
+		wantErr     bool
+	}{
+		{
+			name:        "values correct, should not fail",
+			headerBytes: []byte{0xe4, 0x01, 0xfa, 0xd6, 0x20},
+			wantErr:     false,
+		},
+		{
+			name:        "cid version wrong, should fail",
+			headerBytes: []byte{0xe4, 0x00, 0xfa, 0xd6, 0x20},
+			wantErr:     true,
+		},
+		{
+			name:        "hash length wrong, should fail",
+			headerBytes: []byte{0xe4, 0x01, 0xfa, 0xd6, 0x1f},
+			wantErr:     true,
+		},
+		{
+			name:        "values correct for ipfs, should fail",
+			headerBytes: []byte{0xe3, 0x01, 0x70, 0x12, 0x20},
+			wantErr:     true,
+		},
+	} {
+		t.Run(v.name, func(t *testing.T) {
+			const eipHash = "29f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f"
+
+			var bb []byte
+			buf := make([]byte, binary.MaxVarintLen64)
+			for _, vv := range v.headerBytes {
+				n := binary.PutUvarint(buf, uint64(vv))
+				bb = append(bb, buf[:n]...)
+			}
+
+			h := common.HexToHash(eipHash)
+			bb = append(bb, h[:]...)
+			str := hex.EncodeToString(bb)
+			fmt.Println(str)
+			decodedHash, e := extractContentHash(bb)
+			switch v.wantErr {
+			case true:
+				if e == nil {
+					t.Fatal("the decode should fail")
+				}
+			case false:
+				if e != nil {
+					t.Fatalf("the deccode shouldnt fail: %v", e)
+				}
+				if !bytes.Equal(decodedHash[:], h[:]) {
+					t.Fatal("hashes not equal")
+				}
+			}
+		})
+	}
+}
+
+func TestManuelCidEncode(t *testing.T) {
+	// call cid encode method with hash. expect byte slice returned, compare according to spec
+	const eipHash = "29f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f"
+	cidBytes, err := EncodeSwarmHash(common.HexToHash(eipHash))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// logic in extractContentHash is unit tested thoroughly
+	// hence we just check that the returned hash is equal
+	h, err := extractContentHash(cidBytes)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if bytes.Equal(h[:], cidBytes) {
+		t.Fatal("should be equal")
+	}
+}