From 361724a33e8f2072fb3fb63ccfa9b7e5ef4136a1 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Wed, 28 Aug 2019 19:27:06 +0300
Subject: [PATCH] pkg/core: use util.binaryReader/Writer

Simplify error handling.
---
 pkg/core/account_state.go                |  61 ++++---------
 pkg/core/asset_state.go                  | 108 +++++++----------------
 pkg/core/block.go                        |  40 +++++----
 pkg/core/block_base.go                   |  72 ++++++---------
 pkg/core/header_hash_list.go             |  12 +--
 pkg/core/spent_coin_state.go             |  45 +++-------
 pkg/core/storage/helpers.go              |   8 +-
 pkg/core/transaction/attribute.go        |  93 +++++++++----------
 pkg/core/transaction/claim.go            |  12 ++-
 pkg/core/transaction/input.go            |  20 ++---
 pkg/core/transaction/invocation.go       |  22 ++---
 pkg/core/transaction/output.go           |  25 +++---
 pkg/core/transaction/publish.go          |  50 +++--------
 pkg/core/transaction/register.go         |  49 ++++------
 pkg/core/transaction/state.go            |   6 +-
 pkg/core/transaction/state_descriptor.go |  29 ++----
 pkg/core/transaction/transaction.go      |  55 +++++++-----
 pkg/core/transaction/witness.go          |  30 +++----
 pkg/core/unspent_coin_state.go           |  21 ++---
 19 files changed, 291 insertions(+), 467 deletions(-)

diff --git a/pkg/core/account_state.go b/pkg/core/account_state.go
index 01fecc7a7..44d277e76 100644
--- a/pkg/core/account_state.go
+++ b/pkg/core/account_state.go
@@ -2,7 +2,6 @@ package core
 
 import (
 	"bytes"
-	"encoding/binary"
 	"fmt"
 	"io"
 
@@ -69,17 +68,11 @@ func NewAccountState(scriptHash util.Uint160) *AccountState {
 
 // DecodeBinary decodes AccountState from the given io.Reader.
 func (s *AccountState) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &s.Version); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &s.ScriptHash); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &s.IsFrozen); err != nil {
-		return err
-	}
-
-	lenVotes := util.ReadVarUint(r)
+	br := util.BinReader{R: r}
+	br.ReadLE(&s.Version)
+	br.ReadLE(&s.ScriptHash)
+	br.ReadLE(&s.IsFrozen)
+	lenVotes := br.ReadVarUint()
 	s.Votes = make([]*keys.PublicKey, lenVotes)
 	for i := 0; i < int(lenVotes); i++ {
 		s.Votes[i] = &keys.PublicKey{}
@@ -89,37 +82,25 @@ func (s *AccountState) DecodeBinary(r io.Reader) error {
 	}
 
 	s.Balances = make(map[util.Uint256]util.Fixed8)
-	lenBalances := util.ReadVarUint(r)
+	lenBalances := br.ReadVarUint()
 	for i := 0; i < int(lenBalances); i++ {
 		key := util.Uint256{}
-		if err := binary.Read(r, binary.LittleEndian, &key); err != nil {
-			return err
-		}
+		br.ReadLE(&key)
 		var val util.Fixed8
-		if err := binary.Read(r, binary.LittleEndian, &val); err != nil {
-			return err
-		}
+		br.ReadLE(&val)
 		s.Balances[key] = val
 	}
 
-	return nil
+	return br.Err
 }
 
 // EncodeBinary encode AccountState to the given io.Writer.
 func (s *AccountState) EncodeBinary(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, s.Version); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, s.ScriptHash); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, s.IsFrozen); err != nil {
-		return err
-	}
-
-	if err := util.WriteVarUint(w, uint64(len(s.Votes))); err != nil {
-		return err
-	}
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(s.Version)
+	bw.WriteLE(s.ScriptHash)
+	bw.WriteLE(s.IsFrozen)
+	bw.WriteVarUint(uint64(len(s.Votes)))
 	for _, point := range s.Votes {
 		if err := point.EncodeBinary(w); err != nil {
 			return err
@@ -127,19 +108,13 @@ func (s *AccountState) EncodeBinary(w io.Writer) error {
 	}
 
 	balances := s.nonZeroBalances()
-	if err := util.WriteVarUint(w, uint64(len(balances))); err != nil {
-		return err
-	}
+	bw.WriteVarUint(uint64(len(balances)))
 	for k, v := range balances {
-		if err := binary.Write(w, binary.LittleEndian, k); err != nil {
-			return err
-		}
-		if err := binary.Write(w, binary.LittleEndian, v); err != nil {
-			return err
-		}
+		bw.WriteLE(k)
+		bw.WriteLE(v)
 	}
 
-	return nil
+	return bw.Err
 }
 
 // Returns only the non-zero balances for the account.
diff --git a/pkg/core/asset_state.go b/pkg/core/asset_state.go
index ee4b4407b..19f7db8c3 100644
--- a/pkg/core/asset_state.go
+++ b/pkg/core/asset_state.go
@@ -2,7 +2,6 @@ package core
 
 import (
 	"bytes"
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/core/storage"
@@ -48,95 +47,56 @@ type AssetState struct {
 
 // DecodeBinary implements the Payload interface.
 func (a *AssetState) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &a.ID); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &a.AssetType); err != nil {
-		return err
-	}
+	br := util.BinReader{R: r}
+	br.ReadLE(&a.ID)
+	br.ReadLE(&a.AssetType)
 
-	var err error
-	a.Name, err = util.ReadVarString(r)
-	if err != nil {
-		return err
-	}
+	a.Name = br.ReadString()
 
-	if err := binary.Read(r, binary.LittleEndian, &a.Amount); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &a.Available); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &a.Precision); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &a.FeeMode); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &a.FeeAddress); err != nil {
-		return err
-	}
+	br.ReadLE(&a.Amount)
+	br.ReadLE(&a.Available)
+	br.ReadLE(&a.Precision)
+	br.ReadLE(&a.FeeMode)
+	br.ReadLE(&a.FeeAddress)
 
+	if br.Err != nil {
+		return br.Err
+	}
 	a.Owner = &keys.PublicKey{}
 	if err := a.Owner.DecodeBinary(r); err != nil {
 		return err
 	}
-	if err := binary.Read(r, binary.LittleEndian, &a.Admin); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &a.Issuer); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &a.Expiration); err != nil {
-		return err
-	}
-	return binary.Read(r, binary.LittleEndian, &a.IsFrozen)
+	br.ReadLE(&a.Admin)
+	br.ReadLE(&a.Issuer)
+	br.ReadLE(&a.Expiration)
+	br.ReadLE(&a.IsFrozen)
+
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
 func (a *AssetState) EncodeBinary(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, a.ID); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, a.AssetType); err != nil {
-		return err
-	}
-	if err := util.WriteVarUint(w, uint64(len(a.Name))); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, []byte(a.Name)); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, a.Amount); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, a.Available); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, a.Precision); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, a.FeeMode); err != nil {
-		return err
-	}
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(a.ID)
+	bw.WriteLE(a.AssetType)
+	bw.WriteString(a.Name)
+	bw.WriteLE(a.Amount)
+	bw.WriteLE(a.Available)
+	bw.WriteLE(a.Precision)
+	bw.WriteLE(a.FeeMode)
+	bw.WriteLE(a.FeeAddress)
 
-	if err := binary.Write(w, binary.LittleEndian, a.FeeAddress); err != nil {
-		return err
+	if bw.Err != nil {
+		return bw.Err
 	}
-
 	if err := a.Owner.EncodeBinary(w); err != nil {
 		return err
 	}
-	if err := binary.Write(w, binary.LittleEndian, a.Admin); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, a.Issuer); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, a.Expiration); err != nil {
-		return err
-	}
-	return binary.Write(w, binary.LittleEndian, a.IsFrozen)
+	bw.WriteLE(a.Admin)
+	bw.WriteLE(a.Issuer)
+	bw.WriteLE(a.Expiration)
+	bw.WriteLE(a.IsFrozen)
+	return bw.Err
 }
 
 // GetName returns the asset name based on its type.
diff --git a/pkg/core/block.go b/pkg/core/block.go
index 762ba6787..7744314fd 100644
--- a/pkg/core/block.go
+++ b/pkg/core/block.go
@@ -2,7 +2,6 @@ package core
 
 import (
 	"bytes"
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
@@ -79,9 +78,11 @@ func NewBlockFromTrimmedBytes(b []byte) (*Block, error) {
 		return block, err
 	}
 
+	br := util.BinReader{R: r}
 	var padding uint8
-	if err := binary.Read(r, binary.LittleEndian, &padding); err != nil {
-		return block, err
+	br.ReadLE(&padding)
+	if br.Err != nil {
+		return block, br.Err
 	}
 
 	block.Script = &transaction.Witness{}
@@ -89,17 +90,15 @@ func NewBlockFromTrimmedBytes(b []byte) (*Block, error) {
 		return block, err
 	}
 
-	lenTX := util.ReadVarUint(r)
+	lenTX := br.ReadVarUint()
 	block.Transactions = make([]*transaction.Transaction, lenTX)
 	for i := 0; i < int(lenTX); i++ {
 		var hash util.Uint256
-		if err := binary.Read(r, binary.LittleEndian, &hash); err != nil {
-			return block, err
-		}
+		br.ReadLE(&hash)
 		block.Transactions[i] = transaction.NewTrimmedTX(hash)
 	}
 
-	return block, nil
+	return block, br.Err
 }
 
 // Trim returns a subset of the block data to save up space
@@ -110,23 +109,22 @@ func (b *Block) Trim() ([]byte, error) {
 	if err := b.encodeHashableFields(buf); err != nil {
 		return nil, err
 	}
-	if err := binary.Write(buf, binary.LittleEndian, uint8(1)); err != nil {
-		return nil, err
+	bw := util.BinWriter{W: buf}
+	bw.WriteLE(uint8(1))
+	if bw.Err != nil {
+		return nil, bw.Err
 	}
 	if err := b.Script.EncodeBinary(buf); err != nil {
 		return nil, err
 	}
 
-	lenTX := uint64(len(b.Transactions))
-	if err := util.WriteVarUint(buf, lenTX); err != nil {
-		return nil, err
-	}
+	bw.WriteVarUint(uint64(len(b.Transactions)))
 	for _, tx := range b.Transactions {
-		if err := binary.Write(buf, binary.LittleEndian, tx.Hash()); err != nil {
-			return nil, err
-		}
+		bw.WriteLE(tx.Hash())
+	}
+	if bw.Err != nil {
+		return nil, bw.Err
 	}
-
 	return buf.Bytes(), nil
 }
 
@@ -136,7 +134,11 @@ func (b *Block) DecodeBinary(r io.Reader) error {
 		return err
 	}
 
-	lentx := util.ReadVarUint(r)
+	br := util.BinReader{R: r}
+	lentx := br.ReadVarUint()
+	if br.Err != nil {
+		return br.Err
+	}
 	b.Transactions = make([]*transaction.Transaction, lentx)
 	for i := 0; i < int(lentx); i++ {
 		b.Transactions[i] = &transaction.Transaction{}
diff --git a/pkg/core/block_base.go b/pkg/core/block_base.go
index 608e3e706..00fd4d277 100644
--- a/pkg/core/block_base.go
+++ b/pkg/core/block_base.go
@@ -2,7 +2,6 @@ package core
 
 import (
 	"bytes"
-	"encoding/binary"
 	"fmt"
 	"io"
 
@@ -67,8 +66,10 @@ func (b *BlockBase) DecodeBinary(r io.Reader) error {
 	}
 
 	var padding uint8
-	if err := binary.Read(r, binary.LittleEndian, &padding); err != nil {
-		return err
+	br := util.BinReader{R: r}
+	br.ReadLE(&padding)
+	if br.Err != nil {
+		return br.Err
 	}
 	if padding != 1 {
 		return fmt.Errorf("format error: padding must equal 1 got %d", padding)
@@ -83,8 +84,10 @@ func (b *BlockBase) EncodeBinary(w io.Writer) error {
 	if err := b.encodeHashableFields(w); err != nil {
 		return err
 	}
-	if err := binary.Write(w, binary.LittleEndian, uint8(1)); err != nil {
-		return err
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(uint8(1))
+	if bw.Err != nil {
+		return bw.Err
 	}
 	return b.Script.EncodeBinary(w)
 }
@@ -108,50 +111,31 @@ func (b *BlockBase) createHash() error {
 // encodeHashableFields will only encode the fields used for hashing.
 // see Hash() for more information about the fields.
 func (b *BlockBase) encodeHashableFields(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, b.Version); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, b.PrevHash); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, b.MerkleRoot); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, b.Timestamp); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, b.Index); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, b.ConsensusData); err != nil {
-		return err
-	}
-	return binary.Write(w, binary.LittleEndian, b.NextConsensus)
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(b.Version)
+	bw.WriteLE(b.PrevHash)
+	bw.WriteLE(b.MerkleRoot)
+	bw.WriteLE(b.Timestamp)
+	bw.WriteLE(b.Index)
+	bw.WriteLE(b.ConsensusData)
+	bw.WriteLE(b.NextConsensus)
+	return bw.Err
 }
 
 // decodeHashableFields will only decode the fields used for hashing.
 // see Hash() for more information about the fields.
 func (b *BlockBase) decodeHashableFields(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &b.Version); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &b.PrevHash); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &b.MerkleRoot); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &b.Timestamp); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &b.Index); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &b.ConsensusData); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &b.NextConsensus); err != nil {
-		return err
+	br := util.BinReader{R: r}
+	br.ReadLE(&b.Version)
+	br.ReadLE(&b.PrevHash)
+	br.ReadLE(&b.MerkleRoot)
+	br.ReadLE(&b.Timestamp)
+	br.ReadLE(&b.Index)
+	br.ReadLE(&b.ConsensusData)
+	br.ReadLE(&b.NextConsensus)
+
+	if br.Err != nil {
+		return br.Err
 	}
 
 	// Make the hash of the block here so we dont need to do this
diff --git a/pkg/core/header_hash_list.go b/pkg/core/header_hash_list.go
index ad97b526e..35c190afa 100644
--- a/pkg/core/header_hash_list.go
+++ b/pkg/core/header_hash_list.go
@@ -1,7 +1,6 @@
 package core
 
 import (
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/util"
@@ -60,14 +59,11 @@ func (l *HeaderHashList) Slice(start, end int) []util.Uint256 {
 // WriteTo will write n underlying hashes to the given io.Writer
 // starting from start.
 func (l *HeaderHashList) Write(w io.Writer, start, n int) error {
-	if err := util.WriteVarUint(w, uint64(n)); err != nil {
-		return err
-	}
+	bw := util.BinWriter{W: w}
+	bw.WriteVarUint(uint64(n))
 	hashes := l.Slice(start, start+n)
 	for _, hash := range hashes {
-		if err := binary.Write(w, binary.LittleEndian, hash); err != nil {
-			return err
-		}
+		bw.WriteLE(hash)
 	}
-	return nil
+	return bw.Err
 }
diff --git a/pkg/core/spent_coin_state.go b/pkg/core/spent_coin_state.go
index 9e590dd49..fcfde1ae7 100644
--- a/pkg/core/spent_coin_state.go
+++ b/pkg/core/spent_coin_state.go
@@ -2,7 +2,6 @@ package core
 
 import (
 	"bytes"
-	"encoding/binary"
 	"fmt"
 	"io"
 
@@ -68,49 +67,33 @@ func NewSpentCoinState(hash util.Uint256, height uint32) *SpentCoinState {
 
 // DecodeBinary implements the Payload interface.
 func (s *SpentCoinState) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &s.txHash); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &s.txHeight); err != nil {
-		return err
-	}
+	br := util.BinReader{R: r}
+	br.ReadLE(&s.txHash)
+	br.ReadLE(&s.txHeight)
 
 	s.items = make(map[uint16]uint32)
-	lenItems := util.ReadVarUint(r)
+	lenItems := br.ReadVarUint()
 	for i := 0; i < int(lenItems); i++ {
 		var (
 			key   uint16
 			value uint32
 		)
-		if err := binary.Read(r, binary.LittleEndian, &key); err != nil {
-			return err
-		}
-		if err := binary.Read(r, binary.LittleEndian, &value); err != nil {
-			return err
-		}
+		br.ReadLE(&key)
+		br.ReadLE(&value)
 		s.items[key] = value
 	}
-	return nil
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
 func (s *SpentCoinState) EncodeBinary(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, s.txHash); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, s.txHeight); err != nil {
-		return err
-	}
-	if err := util.WriteVarUint(w, uint64(len(s.items))); err != nil {
-		return err
-	}
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(s.txHash)
+	bw.WriteLE(s.txHeight)
+	bw.WriteVarUint(uint64(len(s.items)))
 	for k, v := range s.items {
-		if err := binary.Write(w, binary.LittleEndian, k); err != nil {
-			return err
-		}
-		if err := binary.Write(w, binary.LittleEndian, v); err != nil {
-			return err
-		}
+		bw.WriteLE(k)
+		bw.WriteLE(v)
 	}
-	return nil
+	return bw.Err
 }
diff --git a/pkg/core/storage/helpers.go b/pkg/core/storage/helpers.go
index b98c7671c..2776da38c 100644
--- a/pkg/core/storage/helpers.go
+++ b/pkg/core/storage/helpers.go
@@ -84,10 +84,12 @@ func HeaderHashes(s Store) ([]util.Uint256, error) {
 // the given byte array.
 func read2000Uint256Hashes(b []byte) ([]util.Uint256, error) {
 	r := bytes.NewReader(b)
-	lenHashes := util.ReadVarUint(r)
+	br := util.BinReader{R: r}
+	lenHashes := br.ReadVarUint()
 	hashes := make([]util.Uint256, lenHashes)
-	if err := binary.Read(r, binary.LittleEndian, hashes); err != nil {
-		return nil, err
+	br.ReadLE(hashes)
+	if br.Err != nil {
+		return nil, br.Err
 	}
 	return hashes, nil
 }
diff --git a/pkg/core/transaction/attribute.go b/pkg/core/transaction/attribute.go
index 783b1dcc3..34bf6443c 100644
--- a/pkg/core/transaction/attribute.go
+++ b/pkg/core/transaction/attribute.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
@@ -18,66 +17,58 @@ type Attribute struct {
 
 // DecodeBinary implements the Payload interface.
 func (attr *Attribute) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &attr.Usage); err != nil {
-		return err
-	}
-	if attr.Usage == ContractHash ||
-		attr.Usage == Vote ||
-		(attr.Usage >= Hash1 && attr.Usage <= Hash15) {
-		attr.Data = make([]byte, 32)
-		return binary.Read(r, binary.LittleEndian, attr.Data)
-	}
+	br := util.BinReader{R: r}
+	br.ReadLE(&attr.Usage)
+
+	// very special case
 	if attr.Usage == ECDH02 || attr.Usage == ECDH03 {
 		attr.Data = make([]byte, 33)
 		attr.Data[0] = byte(attr.Usage)
-		return binary.Read(r, binary.LittleEndian, attr.Data[1:])
+		br.ReadLE(attr.Data[1:])
+		return br.Err
 	}
-	if attr.Usage == Script {
-		attr.Data = make([]byte, 20)
-		return binary.Read(r, binary.LittleEndian, attr.Data)
+	var datasize uint64
+	switch attr.Usage {
+	case ContractHash, Vote, Hash1, Hash2, Hash3, Hash4, Hash5,
+		Hash6, Hash7, Hash8, Hash9, Hash10, Hash11, Hash12, Hash13,
+		Hash14, Hash15:
+		datasize = 32
+	case Script:
+		datasize = 20
+	case DescriptionURL:
+		datasize = 1
+	case Description, Remark, Remark1, Remark2, Remark3, Remark4,
+		Remark5, Remark6, Remark7, Remark8, Remark9, Remark10, Remark11,
+		Remark12, Remark13, Remark14, Remark15:
+		datasize = br.ReadVarUint()
+	default:
+		return fmt.Errorf("failed decoding TX attribute usage: 0x%2x", attr.Usage)
 	}
-	if attr.Usage == DescriptionURL {
-		attr.Data = make([]byte, 1)
-		return binary.Read(r, binary.LittleEndian, attr.Data)
-	}
-	if attr.Usage == Description || attr.Usage >= Remark {
-		lenData := util.ReadVarUint(r)
-		attr.Data = make([]byte, lenData)
-		return binary.Read(r, binary.LittleEndian, attr.Data)
-	}
-	return fmt.Errorf("failed decoding TX attribute usage: 0x%2x", attr.Usage)
+	attr.Data = make([]byte, datasize)
+	br.ReadLE(attr.Data)
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
 func (attr *Attribute) EncodeBinary(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, &attr.Usage); err != nil {
-		return err
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(&attr.Usage)
+	switch attr.Usage {
+	case ECDH02, ECDH03:
+		bw.WriteLE(attr.Data[1:])
+	case DescriptionURL, Description, Remark, Remark1, Remark2, Remark3, Remark4,
+		Remark5, Remark6, Remark7, Remark8, Remark9, Remark10, Remark11,
+		Remark12, Remark13, Remark14, Remark15:
+		bw.WriteVarUint(uint64(len(attr.Data)))
+		fallthrough
+	case Script, ContractHash, Vote, Hash1,	Hash2, Hash3, Hash4, Hash5, Hash6,
+		Hash7, Hash8, Hash9, Hash10, Hash11, Hash12, Hash13, Hash14, Hash15:
+		bw.WriteLE(attr.Data)
+	default:
+		return fmt.Errorf("failed encoding TX attribute usage: 0x%2x", attr.Usage)
 	}
-	if attr.Usage == ContractHash ||
-		attr.Usage == Vote ||
-		(attr.Usage >= Hash1 && attr.Usage <= Hash15) {
-		return binary.Write(w, binary.LittleEndian, attr.Data)
-	}
-	if attr.Usage == ECDH02 || attr.Usage == ECDH03 {
-		attr.Data[0] = byte(attr.Usage)
-		return binary.Write(w, binary.LittleEndian, attr.Data[1:33])
-	}
-	if attr.Usage == Script {
-		return binary.Write(w, binary.LittleEndian, attr.Data)
-	}
-	if attr.Usage == DescriptionURL {
-		if err := util.WriteVarUint(w, uint64(len(attr.Data))); err != nil {
-			return err
-		}
-		return binary.Write(w, binary.LittleEndian, attr.Data)
-	}
-	if attr.Usage == Description || attr.Usage >= Remark {
-		if err := util.WriteVarUint(w, uint64(len(attr.Data))); err != nil {
-			return err
-		}
-		return binary.Write(w, binary.LittleEndian, attr.Data)
-	}
-	return fmt.Errorf("failed encoding TX attribute usage: 0x%2x", attr.Usage)
+
+	return bw.Err
 }
 
 // Size returns the size in number bytes of the Attribute
diff --git a/pkg/core/transaction/claim.go b/pkg/core/transaction/claim.go
index b620ae297..ecb7f0720 100644
--- a/pkg/core/transaction/claim.go
+++ b/pkg/core/transaction/claim.go
@@ -13,7 +13,11 @@ type ClaimTX struct {
 
 // DecodeBinary implements the Payload interface.
 func (tx *ClaimTX) DecodeBinary(r io.Reader) error {
-	lenClaims := util.ReadVarUint(r)
+	br := util.BinReader{R: r}
+	lenClaims := br.ReadVarUint()
+	if br.Err != nil {
+		return br.Err
+	}
 	tx.Claims = make([]*Input, lenClaims)
 	for i := 0; i < int(lenClaims); i++ {
 		tx.Claims[i] = &Input{}
@@ -26,8 +30,10 @@ func (tx *ClaimTX) DecodeBinary(r io.Reader) error {
 
 // EncodeBinary implements the Payload interface.
 func (tx *ClaimTX) EncodeBinary(w io.Writer) error {
-	if err := util.WriteVarUint(w, uint64(len(tx.Claims))); err != nil {
-		return err
+	bw := util.BinWriter{W: w}
+	bw.WriteVarUint(uint64(len(tx.Claims)))
+	if bw.Err != nil {
+		return bw.Err
 	}
 	for _, claim := range tx.Claims {
 		if err := claim.EncodeBinary(w); err != nil {
diff --git a/pkg/core/transaction/input.go b/pkg/core/transaction/input.go
index 23ef80c03..ab923981f 100644
--- a/pkg/core/transaction/input.go
+++ b/pkg/core/transaction/input.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/util"
@@ -18,21 +17,18 @@ type Input struct {
 
 // DecodeBinary implements the Payload interface.
 func (in *Input) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &in.PrevHash); err != nil {
-		return err
-	}
-	return binary.Read(r, binary.LittleEndian, &in.PrevIndex)
+	br := util.BinReader{R: r}
+	br.ReadLE(&in.PrevHash)
+	br.ReadLE(&in.PrevIndex)
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
 func (in *Input) EncodeBinary(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, in.PrevHash); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, in.PrevIndex); err != nil {
-		return err
-	}
-	return nil
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(in.PrevHash)
+	bw.WriteLE(in.PrevIndex)
+	return bw.Err
 }
 
 // Size returns the size in bytes of the Input
diff --git a/pkg/core/transaction/invocation.go b/pkg/core/transaction/invocation.go
index 216d141fb..f07233cfe 100644
--- a/pkg/core/transaction/invocation.go
+++ b/pkg/core/transaction/invocation.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/util"
@@ -34,21 +33,16 @@ func NewInvocationTX(script []byte) *Transaction {
 
 // DecodeBinary implements the Payload interface.
 func (tx *InvocationTX) DecodeBinary(r io.Reader) error {
-	lenScript := util.ReadVarUint(r)
-	tx.Script = make([]byte, lenScript)
-	if err := binary.Read(r, binary.LittleEndian, tx.Script); err != nil {
-		return err
-	}
-	return binary.Read(r, binary.LittleEndian, &tx.Gas)
+	br := util.BinReader{R: r}
+	tx.Script = br.ReadBytes()
+	br.ReadLE(&tx.Gas)
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
 func (tx *InvocationTX) EncodeBinary(w io.Writer) error {
-	if err := util.WriteVarUint(w, uint64(len(tx.Script))); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, tx.Script); err != nil {
-		return err
-	}
-	return binary.Write(w, binary.LittleEndian, tx.Gas)
+	bw := util.BinWriter{W: w}
+	bw.WriteBytes(tx.Script)
+	bw.WriteLE(tx.Gas)
+	return bw.Err
 }
diff --git a/pkg/core/transaction/output.go b/pkg/core/transaction/output.go
index 2898605aa..60a55b5cf 100644
--- a/pkg/core/transaction/output.go
+++ b/pkg/core/transaction/output.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"encoding/json"
 	"io"
 
@@ -36,24 +35,20 @@ func NewOutput(assetID util.Uint256, amount util.Fixed8, scriptHash util.Uint160
 
 // DecodeBinary implements the Payload interface.
 func (out *Output) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &out.AssetID); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &out.Amount); err != nil {
-		return err
-	}
-	return binary.Read(r, binary.LittleEndian, &out.ScriptHash)
+	br := util.BinReader{R: r}
+	br.ReadLE(&out.AssetID)
+	br.ReadLE(&out.Amount)
+	br.ReadLE(&out.ScriptHash)
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
 func (out *Output) EncodeBinary(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, out.AssetID); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, out.Amount); err != nil {
-		return err
-	}
-	return binary.Write(w, binary.LittleEndian, out.ScriptHash)
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(out.AssetID)
+	bw.WriteLE(out.Amount)
+	bw.WriteLE(out.ScriptHash)
+	return bw.Err
 }
 
 // Size returns the size in bytes of the Output
diff --git a/pkg/core/transaction/publish.go b/pkg/core/transaction/publish.go
index ed92409c9..f6a247b92 100644
--- a/pkg/core/transaction/publish.go
+++ b/pkg/core/transaction/publish.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
@@ -24,55 +23,30 @@ type PublishTX struct {
 
 // DecodeBinary implements the Payload interface.
 func (tx *PublishTX) DecodeBinary(r io.Reader) error {
-	var err error
+	br := util.BinReader{R: r}
+	tx.Script = br.ReadBytes()
 
-	tx.Script, err = util.ReadVarBytes(r)
-	if err != nil {
-		return err
-	}
-
-	lenParams := util.ReadVarUint(r)
+	lenParams := br.ReadVarUint()
 	tx.ParamList = make([]smartcontract.ParamType, lenParams)
 	for i := 0; i < int(lenParams); i++ {
 		var ptype uint8
-		if err := binary.Read(r, binary.LittleEndian, &ptype); err != nil {
-			return err
-		}
+		br.ReadLE(&ptype)
 		tx.ParamList[i] = smartcontract.ParamType(ptype)
 	}
 
 	var rtype uint8
-	if err := binary.Read(r, binary.LittleEndian, &rtype); err != nil {
-		return err
-	}
+	br.ReadLE(&rtype)
 	tx.ReturnType = smartcontract.ParamType(rtype)
 
-	if err := binary.Read(r, binary.LittleEndian, &tx.NeedStorage); err != nil {
-		return err
-	}
+	br.ReadLE(&tx.NeedStorage)
 
-	tx.Name, err = util.ReadVarString(r)
-	if err != nil {
-		return err
-	}
-	tx.CodeVersion, err = util.ReadVarString(r)
-	if err != nil {
-		return err
-	}
-	tx.Author, err = util.ReadVarString(r)
-	if err != nil {
-		return err
-	}
-	tx.Email, err = util.ReadVarString(r)
-	if err != nil {
-		return err
-	}
-	tx.Description, err = util.ReadVarString(r)
-	if err != nil {
-		return err
-	}
+	tx.Name = br.ReadString()
+	tx.CodeVersion = br.ReadString()
+	tx.Author = br.ReadString()
+	tx.Email = br.ReadString()
+	tx.Description = br.ReadString()
 
-	return nil
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
diff --git a/pkg/core/transaction/register.go b/pkg/core/transaction/register.go
index 5f2467a47..2d47fd442 100644
--- a/pkg/core/transaction/register.go
+++ b/pkg/core/transaction/register.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
@@ -32,22 +31,15 @@ type RegisterTX struct {
 
 // DecodeBinary implements the Payload interface.
 func (tx *RegisterTX) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &tx.AssetType); err != nil {
-		return err
-	}
+	br := util.BinReader{R: r}
+	br.ReadLE(&tx.AssetType)
 
-	var err error
-	tx.Name, err = util.ReadVarString(r)
-	if err != nil {
-		return err
-	}
+	tx.Name = br.ReadString()
 
-	if err := binary.Read(r, binary.LittleEndian, &tx.Amount); err != nil {
-		return err
-	}
-
-	if err := binary.Read(r, binary.LittleEndian, &tx.Precision); err != nil {
-		return err
+	br.ReadLE(&tx.Amount)
+	br.ReadLE(&tx.Precision)
+	if br.Err != nil {
+		return br.Err
 	}
 
 	tx.Owner = &keys.PublicKey{}
@@ -55,25 +47,18 @@ func (tx *RegisterTX) DecodeBinary(r io.Reader) error {
 		return err
 	}
 
-	return binary.Read(r, binary.LittleEndian, &tx.Admin)
+	br.ReadLE(&tx.Admin)
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
 func (tx *RegisterTX) EncodeBinary(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, tx.AssetType); err != nil {
-		return err
-	}
-	if err := util.WriteVarString(w, tx.Name); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, tx.Amount); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, tx.Precision); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, tx.Owner.Bytes()); err != nil {
-		return err
-	}
-	return binary.Write(w, binary.LittleEndian, tx.Admin)
+	bw := util.BinWriter{W: w}
+	bw.WriteLE(tx.AssetType)
+	bw.WriteString(tx.Name)
+	bw.WriteLE(tx.Amount)
+	bw.WriteLE(tx.Precision)
+	bw.WriteLE(tx.Owner.Bytes())
+	bw.WriteLE(tx.Admin)
+	return bw.Err
 }
diff --git a/pkg/core/transaction/state.go b/pkg/core/transaction/state.go
index 3b61e7f84..6bcbf8e2a 100644
--- a/pkg/core/transaction/state.go
+++ b/pkg/core/transaction/state.go
@@ -13,7 +13,11 @@ type StateTX struct {
 
 // DecodeBinary implements the Payload interface.
 func (tx *StateTX) DecodeBinary(r io.Reader) error {
-	lenDesc := util.ReadVarUint(r)
+	br := util.BinReader{R: r}
+	lenDesc := br.ReadVarUint()
+	if br.Err != nil {
+		return br.Err
+	}
 	for i := 0; i < int(lenDesc); i++ {
 		tx.Descriptors[i] = &StateDescriptor{}
 		if err := tx.Descriptors[i].DecodeBinary(r); err != nil {
diff --git a/pkg/core/transaction/state_descriptor.go b/pkg/core/transaction/state_descriptor.go
index b45b250a3..95f41be52 100644
--- a/pkg/core/transaction/state_descriptor.go
+++ b/pkg/core/transaction/state_descriptor.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/util"
@@ -26,30 +25,14 @@ type StateDescriptor struct {
 
 // DecodeBinary implements the Payload interface.
 func (s *StateDescriptor) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &s.Type); err != nil {
-		return err
-	}
+	br := util.BinReader{R: r}
+	br.ReadLE(&s.Type)
 
-	keyLen := util.ReadVarUint(r)
-	s.Key = make([]byte, keyLen)
-	if err := binary.Read(r, binary.LittleEndian, s.Key); err != nil {
-		return err
-	}
+	s.Key = br.ReadBytes()
+	s.Value = br.ReadBytes()
+	s.Field = br.ReadString()
 
-	valLen := util.ReadVarUint(r)
-	s.Value = make([]byte, valLen)
-	if err := binary.Read(r, binary.LittleEndian, s.Value); err != nil {
-		return err
-	}
-
-	fieldLen := util.ReadVarUint(r)
-	field := make([]byte, fieldLen)
-	if err := binary.Read(r, binary.LittleEndian, field); err != nil {
-		return err
-	}
-	s.Field = string(field)
-
-	return nil
+	return br.Err
 }
 
 // EncodeBinary implements the Payload interface.
diff --git a/pkg/core/transaction/transaction.go b/pkg/core/transaction/transaction.go
index d95f73dd9..fb83461a2 100644
--- a/pkg/core/transaction/transaction.go
+++ b/pkg/core/transaction/transaction.go
@@ -2,7 +2,6 @@ package transaction
 
 import (
 	"bytes"
-	"encoding/binary"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
@@ -79,17 +78,17 @@ func (t *Transaction) AddInput(in *Input) {
 
 // DecodeBinary implements the payload interface.
 func (t *Transaction) DecodeBinary(r io.Reader) error {
-	if err := binary.Read(r, binary.LittleEndian, &t.Type); err != nil {
-		return err
-	}
-	if err := binary.Read(r, binary.LittleEndian, &t.Version); err != nil {
-		return err
+	br := util.BinReader{R: r}
+	br.ReadLE(&t.Type)
+	br.ReadLE(&t.Version)
+	if br.Err != nil {
+		return br.Err
 	}
 	if err := t.decodeData(r); err != nil {
 		return err
 	}
 
-	lenAttrs := util.ReadVarUint(r)
+	lenAttrs := br.ReadVarUint()
 	t.Attributes = make([]*Attribute, lenAttrs)
 	for i := 0; i < int(lenAttrs); i++ {
 		t.Attributes[i] = &Attribute{}
@@ -100,7 +99,7 @@ func (t *Transaction) DecodeBinary(r io.Reader) error {
 		}
 	}
 
-	lenInputs := util.ReadVarUint(r)
+	lenInputs := br.ReadVarUint()
 	t.Inputs = make([]*Input, lenInputs)
 	for i := 0; i < int(lenInputs); i++ {
 		t.Inputs[i] = &Input{}
@@ -109,7 +108,7 @@ func (t *Transaction) DecodeBinary(r io.Reader) error {
 		}
 	}
 
-	lenOutputs := util.ReadVarUint(r)
+	lenOutputs := br.ReadVarUint()
 	t.Outputs = make([]*Output, lenOutputs)
 	for i := 0; i < int(lenOutputs); i++ {
 		t.Outputs[i] = &Output{}
@@ -118,7 +117,7 @@ func (t *Transaction) DecodeBinary(r io.Reader) error {
 		}
 	}
 
-	lenScripts := util.ReadVarUint(r)
+	lenScripts := br.ReadVarUint()
 	t.Scripts = make([]*Witness, lenScripts)
 	for i := 0; i < int(lenScripts); i++ {
 		t.Scripts[i] = &Witness{}
@@ -127,6 +126,9 @@ func (t *Transaction) DecodeBinary(r io.Reader) error {
 		}
 	}
 
+	if br.Err != nil {
+		return br.Err
+	}
 	// Create the hash of the transaction at decode, so we dont need
 	// to do it anymore.
 	return t.createHash()
@@ -172,8 +174,10 @@ func (t *Transaction) EncodeBinary(w io.Writer) error {
 	if err := t.encodeHashableFields(w); err != nil {
 		return err
 	}
-	if err := util.WriteVarUint(w, uint64(len(t.Scripts))); err != nil {
-		return err
+	bw := util.BinWriter{W: w}
+	bw.WriteVarUint(uint64(len(t.Scripts)))
+	if bw.Err != nil {
+		return bw.Err
 	}
 	for _, s := range t.Scripts {
 		if err := s.EncodeBinary(w); err != nil {
@@ -186,11 +190,12 @@ func (t *Transaction) EncodeBinary(w io.Writer) error {
 // encodeHashableFields will only encode the fields that are not used for
 // signing the transaction, which are all fields except the scripts.
 func (t *Transaction) encodeHashableFields(w io.Writer) error {
-	if err := binary.Write(w, binary.LittleEndian, t.Type); err != nil {
-		return err
-	}
-	if err := binary.Write(w, binary.LittleEndian, t.Version); err != nil {
-		return err
+	bw := util.BinWriter{W: w}
+
+	bw.WriteLE(t.Type)
+	bw.WriteLE(t.Version)
+	if bw.Err != nil {
+		return bw.Err
 	}
 
 	// Underlying TXer.
@@ -201,9 +206,9 @@ func (t *Transaction) encodeHashableFields(w io.Writer) error {
 	}
 
 	// Attributes
-	lenAttrs := uint64(len(t.Attributes))
-	if err := util.WriteVarUint(w, lenAttrs); err != nil {
-		return err
+	bw.WriteVarUint(uint64(len(t.Attributes)))
+	if bw.Err != nil {
+		return bw.Err
 	}
 	for _, attr := range t.Attributes {
 		if err := attr.EncodeBinary(w); err != nil {
@@ -212,8 +217,9 @@ func (t *Transaction) encodeHashableFields(w io.Writer) error {
 	}
 
 	// Inputs
-	if err := util.WriteVarUint(w, uint64(len(t.Inputs))); err != nil {
-		return err
+	bw.WriteVarUint(uint64(len(t.Inputs)))
+	if bw.Err != nil {
+		return bw.Err
 	}
 	for _, in := range t.Inputs {
 		if err := in.EncodeBinary(w); err != nil {
@@ -222,8 +228,9 @@ func (t *Transaction) encodeHashableFields(w io.Writer) error {
 	}
 
 	// Outputs
-	if err := util.WriteVarUint(w, uint64(len(t.Outputs))); err != nil {
-		return err
+	bw.WriteVarUint(uint64(len(t.Outputs)))
+	if bw.Err != nil {
+		return bw.Err
 	}
 	for _, out := range t.Outputs {
 		if err := out.EncodeBinary(w); err != nil {
diff --git a/pkg/core/transaction/witness.go b/pkg/core/transaction/witness.go
index cf10d8bb2..125fede63 100644
--- a/pkg/core/transaction/witness.go
+++ b/pkg/core/transaction/witness.go
@@ -1,7 +1,6 @@
 package transaction
 
 import (
-	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
 	"io"
@@ -18,28 +17,21 @@ type Witness struct {
 
 // DecodeBinary implements the payload interface.
 func (w *Witness) DecodeBinary(r io.Reader) error {
-	lenb := util.ReadVarUint(r)
-	w.InvocationScript = make([]byte, lenb)
-	if err := binary.Read(r, binary.LittleEndian, w.InvocationScript); err != nil {
-		return err
-	}
-	lenb = util.ReadVarUint(r)
-	w.VerificationScript = make([]byte, lenb)
-	return binary.Read(r, binary.LittleEndian, w.VerificationScript)
+	br := util.BinReader{R: r}
+
+	w.InvocationScript = br.ReadBytes()
+	w.VerificationScript = br.ReadBytes()
+	return br.Err
 }
 
 // EncodeBinary implements the payload interface.
 func (w *Witness) EncodeBinary(writer io.Writer) error {
-	if err := util.WriteVarUint(writer, uint64(len(w.InvocationScript))); err != nil {
-		return err
-	}
-	if err := binary.Write(writer, binary.LittleEndian, w.InvocationScript); err != nil {
-		return err
-	}
-	if err := util.WriteVarUint(writer, uint64(len(w.VerificationScript))); err != nil {
-		return err
-	}
-	return binary.Write(writer, binary.LittleEndian, w.VerificationScript)
+	bw := util.BinWriter{W: writer}
+
+	bw.WriteBytes(w.InvocationScript)
+	bw.WriteBytes(w.VerificationScript)
+
+	return bw.Err
 }
 
 // MarshalJSON implements the json marshaller interface.
diff --git a/pkg/core/unspent_coin_state.go b/pkg/core/unspent_coin_state.go
index e588e0575..e8972934f 100644
--- a/pkg/core/unspent_coin_state.go
+++ b/pkg/core/unspent_coin_state.go
@@ -2,7 +2,6 @@ package core
 
 import (
 	"bytes"
-	"encoding/binary"
 	"fmt"
 	"io"
 
@@ -68,29 +67,25 @@ func (u UnspentCoins) commit(b storage.Batch) error {
 
 // EncodeBinary encodes UnspentCoinState to the given io.Writer.
 func (s *UnspentCoinState) EncodeBinary(w io.Writer) error {
-	if err := util.WriteVarUint(w, uint64(len(s.states))); err != nil {
-		return err
-	}
+	bw := util.BinWriter{W: w}
+	bw.WriteVarUint(uint64(len(s.states)))
 	for _, state := range s.states {
-		if err := binary.Write(w, binary.LittleEndian, byte(state)); err != nil {
-			return err
-		}
+		bw.WriteLE(byte(state))
 	}
-	return nil
+	return bw.Err
 }
 
 // DecodeBinary decodes UnspentCoinState from the given io.Reader.
 func (s *UnspentCoinState) DecodeBinary(r io.Reader) error {
-	lenStates := util.ReadVarUint(r)
+	br := util.BinReader{R: r}
+	lenStates := br.ReadVarUint()
 	s.states = make([]CoinState, lenStates)
 	for i := 0; i < int(lenStates); i++ {
 		var state uint8
-		if err := binary.Read(r, binary.LittleEndian, &state); err != nil {
-			return err
-		}
+		br.ReadLE(&state)
 		s.states[i] = CoinState(state)
 	}
-	return nil
+	return br.Err
 }
 
 // IsDoubleSpend verifies that the input transactions are not double spent.