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authorethersphere <thesw@rm.eth>2018-06-20 20:06:27 +0800
committerethersphere <thesw@rm.eth>2018-06-22 03:10:31 +0800
commite187711c6545487d4cac3701f0f506bb536234e2 (patch)
treed2f6150f70b84b36e49a449082aeda267b4b9046 /swarm/multihash
parent574378edb50c907b532946a1d4654dbd6701b20a (diff)
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swarm: network rewrite merge
Diffstat (limited to 'swarm/multihash')
-rw-r--r--swarm/multihash/multihash.go92
-rw-r--r--swarm/multihash/multihash_test.go53
2 files changed, 145 insertions, 0 deletions
diff --git a/swarm/multihash/multihash.go b/swarm/multihash/multihash.go
new file mode 100644
index 000000000..3306e3a6d
--- /dev/null
+++ b/swarm/multihash/multihash.go
@@ -0,0 +1,92 @@
+// Copyright 2018 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 multihash
+
+import (
+ "bytes"
+ "encoding/binary"
+ "errors"
+ "fmt"
+)
+
+const (
+ defaultMultihashLength = 32
+ defaultMultihashTypeCode = 0x1b
+)
+
+var (
+ multihashTypeCode uint8
+ MultihashLength = defaultMultihashLength
+)
+
+func init() {
+ multihashTypeCode = defaultMultihashTypeCode
+ MultihashLength = defaultMultihashLength
+}
+
+// check if valid swarm multihash
+func isSwarmMultihashType(code uint8) bool {
+ return code == multihashTypeCode
+}
+
+// GetMultihashLength returns the digest length of the provided multihash
+// It will fail if the multihash is not a valid swarm mulithash
+func GetMultihashLength(data []byte) (int, int, error) {
+ cursor := 0
+ typ, c := binary.Uvarint(data)
+ if c <= 0 {
+ return 0, 0, errors.New("unreadable hashtype field")
+ }
+ if !isSwarmMultihashType(uint8(typ)) {
+ return 0, 0, fmt.Errorf("hash code %x is not a swarm hashtype", typ)
+ }
+ cursor += c
+ hashlength, c := binary.Uvarint(data[cursor:])
+ if c <= 0 {
+ return 0, 0, errors.New("unreadable length field")
+ }
+ cursor += c
+
+ // we cheekily assume hashlength < maxint
+ inthashlength := int(hashlength)
+ if len(data[c:]) < inthashlength {
+ return 0, 0, errors.New("length mismatch")
+ }
+ return inthashlength, cursor, nil
+}
+
+// FromMulithash returns the digest portion of the multihash
+// It will fail if the multihash is not a valid swarm multihash
+func FromMultihash(data []byte) ([]byte, error) {
+ hashLength, _, err := GetMultihashLength(data)
+ if err != nil {
+ return nil, err
+ }
+ return data[len(data)-hashLength:], nil
+}
+
+// ToMulithash wraps the provided digest data with a swarm mulithash header
+func ToMultihash(hashData []byte) []byte {
+ buf := bytes.NewBuffer(nil)
+ b := make([]byte, 8)
+ c := binary.PutUvarint(b, uint64(multihashTypeCode))
+ buf.Write(b[:c])
+ c = binary.PutUvarint(b, uint64(len(hashData)))
+ buf.Write(b[:c])
+ buf.Write(hashData)
+ return buf.Bytes()
+}
diff --git a/swarm/multihash/multihash_test.go b/swarm/multihash/multihash_test.go
new file mode 100644
index 000000000..85df741dd
--- /dev/null
+++ b/swarm/multihash/multihash_test.go
@@ -0,0 +1,53 @@
+// Copyright 2018 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 multihash
+
+import (
+ "bytes"
+ "math/rand"
+ "testing"
+)
+
+// parse multihash, and check that invalid multihashes fail
+func TestCheckMultihash(t *testing.T) {
+ hashbytes := make([]byte, 32)
+ c, err := rand.Read(hashbytes)
+ if err != nil {
+ t.Fatal(err)
+ } else if c < 32 {
+ t.Fatal("short read")
+ }
+
+ expected := ToMultihash(hashbytes)
+
+ l, hl, _ := GetMultihashLength(expected)
+ if l != 32 {
+ t.Fatalf("expected length %d, got %d", 32, l)
+ } else if hl != 2 {
+ t.Fatalf("expected header length %d, got %d", 2, hl)
+ }
+ if _, _, err := GetMultihashLength(expected[1:]); err == nil {
+ t.Fatal("expected failure on corrupt header")
+ }
+ if _, _, err := GetMultihashLength(expected[:len(expected)-2]); err == nil {
+ t.Fatal("expected failure on short content")
+ }
+ dh, _ := FromMultihash(expected)
+ if !bytes.Equal(dh, hashbytes) {
+ t.Fatalf("expected content hash %x, got %x", hashbytes, dh)
+ }
+}