From 97c3fdfaa2fd076400c4d72dd7bcf7a3ec9e62f4 Mon Sep 17 00:00:00 2001
From: Oliver Gugger <gugger@gmail.com>
Date: Mon, 27 Sep 2021 14:24:40 +0200
Subject: [PATCH 1/2] ci: add Makefile, use golangci-lint

With this commit we add a Makefile with the goal of removing the
goclean.sh script. We also use the more powerful golangci-lint linter
and split the GitHub actions into multiple sections to parallelize them.
---
 .github/workflows/go.yml |  63 ++++++++++++++++-----
 .gitignore               |   2 +
 .golangci.yml            |  54 ++++++++++++++++++
 Makefile                 | 116 +++++++++++++++++++++++++++++++++++++++
 goclean.sh               |  46 ----------------
 test_coverage.txt        |  72 ------------------------
 6 files changed, 220 insertions(+), 133 deletions(-)
 create mode 100644 .golangci.yml
 create mode 100644 Makefile
 delete mode 100755 goclean.sh
 delete mode 100644 test_coverage.txt

diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index d82b525..541cc82 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -1,31 +1,64 @@
 name: Build and Test
 on: [push, pull_request]
+
+env:
+  # go needs absolute directories, using the $HOME variable doesn't work here.
+  GOCACHE: /home/runner/work/go/pkg/build
+  GOPATH: /home/runner/work/go
+  GO_VERSION: 1.16.8
+
 jobs:
   build:
-    name: Go CI
+    name: Build
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        go: [1.14, 1.15]
     steps:
       - name: Set up Go
         uses: actions/setup-go@v2
         with:
-          go-version: ${{ matrix.go }}
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Check out source
         uses: actions/checkout@v2
-      - name: Install Linters
-        run: "curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.31.0"
+
       - name: Build
-        env:
-          GO111MODULE: "on"
-        run: go build ./...
+        run: make build
+
+  test-cover:
+    name: Unit coverage
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
+      - name: Check out source
+        uses: actions/checkout@v2
+
       - name: Test
-        env:
-          GO111MODULE: "on"
-        run: |
-          sh ./goclean.sh
+        run: make unit-cover
+
       - name: Send btcutil coverage
         uses: shogo82148/actions-goveralls@v1
         with:
-          path-to-profile: profile.cov
+          path-to-profile: coverage.txt
+
+      - name: Send btcutil coverage for psbt package
+        uses: shogo82148/actions-goveralls@v1
+        with:
+          path-to-profile: psbt/coverage.txt
+
+  test-race:
+    name: Unit race
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
+      - name: Check out source
+        uses: actions/checkout@v2
+
+      - name: Test
+        run: make unit-race
diff --git a/.gitignore b/.gitignore
index 5b97dbb..4b0deb0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,3 +26,5 @@ _cgo_export.*
 _testmain.go
 
 *.exe 
+coverage.txt
+psbt/coverage.txt
diff --git a/.golangci.yml b/.golangci.yml
new file mode 100644
index 0000000..9ee85c4
--- /dev/null
+++ b/.golangci.yml
@@ -0,0 +1,54 @@
+run:
+  # timeout for analysis
+  deadline: 10m
+
+linters-settings:
+  govet:
+    # Don't report about shadowed variables
+    check-shadowing: false
+  gofmt:
+    # simplify code: gofmt with `-s` option, true by default
+    simplify: true
+
+linters:
+  enable-all: true
+  disable:
+    # Global variables are used in many places throughout the code base.
+    - gochecknoglobals
+
+    # Some lines are over 80 characters on purpose and we don't want to make them
+    # even longer by marking them as 'nolint'.
+    - lll
+
+    # We don't care (enough) about misaligned structs to lint that.
+    - maligned
+
+    # We have long functions, especially in tests. Moving or renaming those would
+    # trigger funlen problems that we may not want to solve at that time.
+    - funlen
+
+    # Disable for now as we haven't yet tuned the sensitivity to our codebase
+    # yet.  Enabling by default for example, would also force new contributors to
+    # potentially extensively refactor code, when they want to smaller change to
+    # land.
+    - gocyclo
+
+    # Instances of table driven tests that don't pre-allocate shouldn't trigger
+    # the linter.
+    - prealloc
+
+    # Init functions are used by loggers throughout the codebase.
+    - gochecknoinits
+
+    # Explicit types are okay.
+    - interfacer
+
+issues:
+  exclude-rules:
+    # Exclude gosec from running for tests so that tests with weak randomness
+    # (math/rand) will pass the linter.
+    - path: _test\.go
+      linters:
+        - gosec
+        #- errcheck
+        - dupl
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..c627e88
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,116 @@
+PKG := github.com/btcsuite/btcutil
+
+LINT_PKG := github.com/golangci/golangci-lint/cmd/golangci-lint
+GOACC_PKG := github.com/ory/go-acc
+GOIMPORTS_PKG := golang.org/x/tools/cmd/goimports
+
+GO_BIN := ${GOPATH}/bin
+LINT_BIN := $(GO_BIN)/golangci-lint
+GOACC_BIN := $(GO_BIN)/go-acc
+
+LINT_COMMIT := v1.18.0
+GOACC_COMMIT := 80342ae2e0fcf265e99e76bcc4efd022c7c3811b
+
+DEPGET := cd /tmp && GO111MODULE=on go get -v
+GOBUILD := GO111MODULE=on go build -v
+GOINSTALL := GO111MODULE=on go install -v
+GOTEST := GO111MODULE=on go test 
+
+GOFILES_NOVENDOR = $(shell find . -type f -name '*.go' -not -path "./vendor/*")
+
+RM := rm -f
+CP := cp
+MAKE := make
+XARGS := xargs -L 1
+
+# Linting uses a lot of memory, so keep it under control by limiting the number
+# of workers if requested.
+ifneq ($(workers),)
+LINT_WORKERS = --concurrency=$(workers)
+endif
+
+LINT = $(LINT_BIN) run -v $(LINT_WORKERS)
+
+GREEN := "\\033[0;32m"
+NC := "\\033[0m"
+define print
+	echo $(GREEN)$1$(NC)
+endef
+
+default: build
+
+all: build check
+
+# ============
+# DEPENDENCIES
+# ============
+
+$(LINT_BIN):
+	@$(call print, "Fetching linter")
+	$(DEPGET) $(LINT_PKG)@$(LINT_COMMIT)
+
+$(GOACC_BIN):
+	@$(call print, "Fetching go-acc")
+	$(DEPGET) $(GOACC_PKG)@$(GOACC_COMMIT)
+
+goimports:
+	@$(call print, "Installing goimports.")
+	$(DEPGET) $(GOIMPORTS_PKG)
+
+# ============
+# INSTALLATION
+# ============
+
+build:
+	@$(call print, "Compiling btcutil.")
+	$(GOBUILD) $(PKG)/...
+
+# =======
+# TESTING
+# =======
+
+check: unit
+
+unit:
+	@$(call print, "Running unit tests.")
+	$(GOTEST) ./... -test.timeout=20m
+	cd psbt; $(GOTEST) ./... -test.timeout=20m
+
+unit-cover: $(GOACC_BIN)
+	@$(call print, "Running unit coverage tests.")
+	$(GOACC_BIN) ./...
+	cd psbt; $(GOACC_BIN) ./...
+
+unit-race:
+	@$(call print, "Running unit race tests.")
+	env CGO_ENABLED=1 GORACE="history_size=7 halt_on_errors=1" $(GOTEST) -race -test.timeout=20m ./...
+	cd psbt; env CGO_ENABLED=1 GORACE="history_size=7 halt_on_errors=1" $(GOTEST) -race -test.timeout=20m ./...
+
+# =========
+# UTILITIES
+# =========
+
+fmt: goimports
+	@$(call print, "Fixing imports.")
+	goimports -w $(GOFILES_NOVENDOR)
+	@$(call print, "Formatting source.")
+	gofmt -l -w -s $(GOFILES_NOVENDOR)
+
+lint: $(LINT_BIN)
+	@$(call print, "Linting source.")
+	$(LINT)
+
+clean:
+	@$(call print, "Cleaning source.$(NC)")
+	$(RM) coverage.txt psbt/coverage.txt
+
+.PHONY: all \
+	default \
+	build \
+	check \
+	unit \
+	unit-cover \
+	unit-race \
+	fmt \
+	lint \
+	clean
diff --git a/goclean.sh b/goclean.sh
deleted file mode 100755
index a9fe858..0000000
--- a/goclean.sh
+++ /dev/null
@@ -1,46 +0,0 @@
-#!/bin/bash
-# The script does automatic checking on a Go package and its sub-packages, including:
-# 1. gofmt         (http://golang.org/cmd/gofmt/)
-# 2. goimports     (https://github.com/bradfitz/goimports)
-# 3. golint        (https://github.com/golang/lint)
-# 4. go vet        (http://golang.org/cmd/vet)
-# 5. gosimple      (https://github.com/dominikh/go-simple)
-# 6. unconvert     (https://github.com/mdempsky/unconvert)
-# 7. race detector (http://blog.golang.org/race-detector)
-# 8. test coverage (http://blog.golang.org/cover)
-#
-
-set -ex
-
-# Automatic checks
-for i in $(find . -name go.mod -type f -print); do
-  module=$(dirname ${i})
-  echo "==> ${module}"
-
-  MODNAME=$(echo $module | sed -E -e "s/^$ROOTPATHPATTERN//" \
-    -e 's,^/,,' -e 's,/v[0-9]+$,,')
-  if [ -z "$MODNAME" ]; then
-    MODNAME=.
-  fi
-
-  # run tests
-  (cd $MODNAME &&
-    echo "mode: atomic" > profile.cov && \
-    env GORACE=halt_on_error=1 go test -race -covermode=atomic -coverprofile=profile.tmp ./... && \
-    cat profile.tmp | tail -n +2 >> profile.cov && \
-    rm profile.tmp && \
-    go tool cover -func profile.cov
-  )
-
-  # check linters
-  (cd $MODNAME && \
-    go mod download && \
-    golangci-lint run --deadline=10m --disable-all \
-      --enable=gofmt \
-      --enable=goimports \
-      --enable=golint \
-      --enable=govet \
-      --enable=gosimple \
-      --enable=unconvert
-  )
-done
diff --git a/test_coverage.txt b/test_coverage.txt
deleted file mode 100644
index e475fad..0000000
--- a/test_coverage.txt
+++ /dev/null
@@ -1,72 +0,0 @@
-
-github.com/conformal/btcutil/base58.go	 Base58Decode			 100.00% (20/20)
-github.com/conformal/btcutil/base58.go	 Base58Encode			 100.00% (15/15)
-github.com/conformal/btcutil/block.go	 Block.Tx			 100.00% (12/12)
-github.com/conformal/btcutil/wif.go	 WIF.String			 100.00% (11/11)
-github.com/conformal/btcutil/block.go	 Block.Transactions		 100.00% (11/11)
-github.com/conformal/btcutil/amount.go	 AmountUnit.String		 100.00% (8/8)
-github.com/conformal/btcutil/tx.go	 NewTxFromReader		 100.00% (6/6)
-github.com/conformal/btcutil/block.go	 NewBlockFromBytes		 100.00% (6/6)
-github.com/conformal/btcutil/block.go	 NewBlockFromReader		 100.00% (6/6)
-github.com/conformal/btcutil/address.go	 encodeAddress			 100.00% (6/6)
-github.com/conformal/btcutil/address.go	 newAddressPubKeyHash		 100.00% (5/5)
-github.com/conformal/btcutil/address.go	 newAddressScriptHashFromHash	 100.00% (5/5)
-github.com/conformal/btcutil/tx.go	 Tx.Sha				 100.00% (5/5)
-github.com/conformal/btcutil/block.go	 Block.Sha			 100.00% (5/5)
-github.com/conformal/btcutil/amount.go	 NewAmount			 100.00% (5/5)
-github.com/conformal/btcutil/amount.go	 round				 100.00% (3/3)
-github.com/conformal/btcutil/address.go	 NewAddressScriptHash		 100.00% (2/2)
-github.com/conformal/btcutil/amount.go	 Amount.Format			 100.00% (2/2)
-github.com/conformal/btcutil/tx.go	 NewTxFromBytes			 100.00% (2/2)
-github.com/conformal/btcutil/hash160.go	 calcHash			 100.00% (2/2)
-github.com/conformal/btcutil/address.go	 AddressPubKeyHash.Hash160	 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 OutOfRangeError.Error		 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.MsgBlock			 100.00% (1/1)
-github.com/conformal/btcutil/tx.go	 Tx.MsgTx			 100.00% (1/1)
-github.com/conformal/btcutil/hash160.go	 Hash160			 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 NewBlockFromBlockAndBytes	 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.Height			 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.SetHeight		 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 NewBlock			 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKeyHash.IsForNet	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKey.EncodeAddress	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 NewAddressPubKeyHash		 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKeyHash.EncodeAddress 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKeyHash.ScriptAddress 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKeyHash.String	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 NewAddressScriptHashFromHash	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressScriptHash.EncodeAddress 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressScriptHash.ScriptAddress 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressScriptHash.IsForNet	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressScriptHash.String	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressScriptHash.Hash160	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKey.ScriptAddress	 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKey.IsForNet		 100.00% (1/1)
-github.com/conformal/btcutil/address.go	 AddressPubKey.String		 100.00% (1/1)
-github.com/conformal/btcutil/tx.go	 NewTx				 100.00% (1/1)
-github.com/conformal/btcutil/tx.go	 Tx.SetIndex			 100.00% (1/1)
-github.com/conformal/btcutil/amount.go	 Amount.ToUnit			 100.00% (1/1)
-github.com/conformal/btcutil/tx.go	 Tx.Index			 100.00% (1/1)
-github.com/conformal/btcutil/amount.go	 Amount.String			 100.00% (1/1)
-github.com/conformal/btcutil/amount.go	 Amount.MulF64			 100.00% (1/1)
-github.com/conformal/btcutil/appdata.go	 appDataDir			 92.00% (23/25)
-github.com/conformal/btcutil/block.go	 Block.TxLoc			 88.89% (8/9)
-github.com/conformal/btcutil/block.go	 Block.Bytes			 88.89% (8/9)
-github.com/conformal/btcutil/address.go	 NewAddressPubKey		 87.50% (7/8)
-github.com/conformal/btcutil/address.go	 DecodeAddress			 85.00% (17/20)
-github.com/conformal/btcutil/wif.go	 DecodeWIF			 85.00% (17/20)
-github.com/conformal/btcutil/address.go	 AddressPubKey.serialize	 80.00% (4/5)
-github.com/conformal/btcutil/block.go	 Block.TxSha			 75.00% (3/4)
-github.com/conformal/btcutil/wif.go	 paddedAppend			 66.67% (2/3)
-github.com/conformal/btcutil/wif.go	 NewWIF				 66.67% (2/3)
-github.com/conformal/btcutil/certgen.go	 NewTLSCertPair			 0.00% (0/54)
-github.com/conformal/btcutil/wif.go	 WIF.SerializePubKey		 0.00% (0/4)
-github.com/conformal/btcutil/address.go	 AddressPubKey.AddressPubKeyHash 0.00% (0/3)
-github.com/conformal/btcutil/address.go	 AddressPubKey.Format		 0.00% (0/1)
-github.com/conformal/btcutil/address.go	 AddressPubKey.PubKey		 0.00% (0/1)
-github.com/conformal/btcutil/address.go	 AddressPubKey.SetFormat	 0.00% (0/1)
-github.com/conformal/btcutil/wif.go	 WIF.IsForNet			 0.00% (0/1)
-github.com/conformal/btcutil/appdata.go	 AppDataDir			 0.00% (0/1)
-github.com/conformal/btcutil/net.go	 interfaceAddrs			 0.00% (0/1)
-github.com/conformal/btcutil		 ------------------------------- 75.88% (258/340)
-

From 12d7d04b3139ab8dffb23ab0e35035a94ea1c401 Mon Sep 17 00:00:00 2001
From: Oliver Gugger <gugger@gmail.com>
Date: Mon, 27 Sep 2021 14:27:51 +0200
Subject: [PATCH 2/2] multi: fix linter issues

---
 address.go                     | 10 +++++-----
 address_test.go                |  2 +-
 base58/base58check.go          |  2 +-
 base58/base58check_test.go     | 11 +++++++----
 bech32/bech32.go               |  6 +++---
 bloom/merkleblock.go           |  2 +-
 certgen.go                     |  2 +-
 coinset/coins_test.go          |  2 +-
 gcs/builder/builder.go         |  4 ++--
 gcs/builder/builder_test.go    |  3 ---
 gcs/gcs.go                     |  6 +++---
 gcs/gcs_test.go                |  4 +++-
 gcs/gcsbench_test.go           | 11 +++++++----
 hash160.go                     |  2 +-
 hdkeychain/bench_test.go       |  8 ++++----
 hdkeychain/extendedkey.go      |  6 +++---
 hdkeychain/extendedkey_test.go |  2 +-
 wif_test.go                    |  4 ++++
 18 files changed, 48 insertions(+), 39 deletions(-)

diff --git a/address.go b/address.go
index 8672497..75503ed 100644
--- a/address.go
+++ b/address.go
@@ -41,7 +41,7 @@ var (
 
 	// ErrUnknownAddressType describes an error where an address can not
 	// decoded as a specific address type due to the string encoding
-	// begining with an identifier byte unknown to any standard or
+	// beginning with an identifier byte unknown to any standard or
 	// registered (via chaincfg.Register) network.
 	ErrUnknownAddressType = errors.New("unknown address type")
 
@@ -265,7 +265,7 @@ func NewAddressPubKeyHash(pkHash []byte, net *chaincfg.Params) (*AddressPubKeyHa
 // newAddressPubKeyHash is the internal API to create a pubkey hash address
 // with a known leading identifier byte for a network, rather than looking
 // it up through its parameters.  This is useful when creating a new address
-// structure from a string encoding where the identifer byte is already
+// structure from a string encoding where the identifier byte is already
 // known.
 func newAddressPubKeyHash(pkHash []byte, netID byte) (*AddressPubKeyHash, error) {
 	// Check for a valid pubkey hash length.
@@ -304,7 +304,7 @@ func (a *AddressPubKeyHash) String() string {
 }
 
 // Hash160 returns the underlying array of the pubkey hash.  This can be useful
-// when an array is more appropiate than a slice (for example, when used as map
+// when an array is more appropriate than a slice (for example, when used as map
 // keys).
 func (a *AddressPubKeyHash) Hash160() *[ripemd160.Size]byte {
 	return &a.hash
@@ -332,7 +332,7 @@ func NewAddressScriptHashFromHash(scriptHash []byte, net *chaincfg.Params) (*Add
 // newAddressScriptHashFromHash is the internal API to create a script hash
 // address with a known leading identifier byte for a network, rather than
 // looking it up through its parameters.  This is useful when creating a new
-// address structure from a string encoding where the identifer byte is already
+// address structure from a string encoding where the identifier byte is already
 // known.
 func newAddressScriptHashFromHash(scriptHash []byte, netID byte) (*AddressScriptHash, error) {
 	// Check for a valid script hash length.
@@ -371,7 +371,7 @@ func (a *AddressScriptHash) String() string {
 }
 
 // Hash160 returns the underlying array of the script hash.  This can be useful
-// when an array is more appropiate than a slice (for example, when used as map
+// when an array is more appropriate than a slice (for example, when used as map
 // keys).
 func (a *AddressScriptHash) Hash160() *[ripemd160.Size]byte {
 	return &a.hash
diff --git a/address_test.go b/address_test.go
index b6a990d..bbca3de 100644
--- a/address_test.go
+++ b/address_test.go
@@ -766,7 +766,7 @@ func TestAddresses(t *testing.T) {
 			// Encode again and compare against the original.
 			encoded := decoded.EncodeAddress()
 			if test.encoded != encoded {
-				t.Errorf("%v: decoding and encoding produced different addressess: %v != %v",
+				t.Errorf("%v: decoding and encoding produced different addresses: %v != %v",
 					test.name, test.encoded, encoded)
 				return
 			}
diff --git a/base58/base58check.go b/base58/base58check.go
index 7cdafee..402c323 100644
--- a/base58/base58check.go
+++ b/base58/base58check.go
@@ -28,7 +28,7 @@ func checksum(input []byte) (cksum [4]byte) {
 func CheckEncode(input []byte, version byte) string {
 	b := make([]byte, 0, 1+len(input)+4)
 	b = append(b, version)
-	b = append(b, input[:]...)
+	b = append(b, input...)
 	cksum := checksum(b)
 	b = append(b, cksum[:]...)
 	return Encode(b)
diff --git a/base58/base58check_test.go b/base58/base58check_test.go
index 7c6350b..20a4177 100644
--- a/base58/base58check_test.go
+++ b/base58/base58check_test.go
@@ -37,11 +37,14 @@ func TestBase58Check(t *testing.T) {
 
 		// test decoding
 		res, version, err := base58.CheckDecode(test.out)
-		if err != nil {
+		switch {
+		case err != nil:
 			t.Errorf("CheckDecode test #%d failed with err: %v", x, err)
-		} else if version != test.version {
+
+		case version != test.version:
 			t.Errorf("CheckDecode test #%d failed: got version: %d want: %d", x, version, test.version)
-		} else if string(res) != test.in {
+
+		case string(res) != test.in:
 			t.Errorf("CheckDecode test #%d failed: got: %s want: %s", x, res, test.in)
 		}
 	}
@@ -56,7 +59,7 @@ func TestBase58Check(t *testing.T) {
 	// bytes are missing).
 	testString := ""
 	for len := 0; len < 4; len++ {
-		testString = testString + "x"
+		testString += "x"
 		_, _, err = base58.CheckDecode(testString)
 		if err != base58.ErrInvalidFormat {
 			t.Error("Checkdecode test failed, expected ErrInvalidFormat")
diff --git a/bech32/bech32.go b/bech32/bech32.go
index 1bc75a3..c1e0010 100644
--- a/bech32/bech32.go
+++ b/bech32/bech32.go
@@ -362,7 +362,7 @@ func ConvertBits(data []byte, fromBits, toBits uint8, pad bool) ([]byte, error)
 	for _, b := range data {
 
 		// Discard unused bits.
-		b = b << (8 - fromBits)
+		b <<= 8 - fromBits
 
 		// How many bits remaining to extract from the input data.
 		remFromBits := fromBits
@@ -383,7 +383,7 @@ func ConvertBits(data []byte, fromBits, toBits uint8, pad bool) ([]byte, error)
 
 			// Discard the bits we just extracted and get ready for
 			// next iteration.
-			b = b << toExtract
+			b <<= toExtract
 			remFromBits -= toExtract
 			filledBits += toExtract
 
@@ -399,7 +399,7 @@ func ConvertBits(data []byte, fromBits, toBits uint8, pad bool) ([]byte, error)
 
 	// We pad any unfinished group if specified.
 	if pad && filledBits > 0 {
-		nextByte = nextByte << (toBits - filledBits)
+		nextByte <<= toBits - filledBits
 		regrouped = append(regrouped, nextByte)
 		filledBits = 0
 		nextByte = 0
diff --git a/bloom/merkleblock.go b/bloom/merkleblock.go
index d6796ba..b1da716 100644
--- a/bloom/merkleblock.go
+++ b/bloom/merkleblock.go
@@ -116,7 +116,7 @@ func NewMerkleBlock(block *btcutil.Block, filter *Filter) (*wire.MsgMerkleBlock,
 		Flags:        make([]byte, (len(mBlock.bits)+7)/8),
 	}
 	for _, hash := range mBlock.finalHashes {
-		msgMerkleBlock.AddTxHash(hash)
+		_ = msgMerkleBlock.AddTxHash(hash)
 	}
 	for i := uint32(0); i < uint32(len(mBlock.bits)); i++ {
 		msgMerkleBlock.Flags[i/8] |= mBlock.bits[i] << (i % 8)
diff --git a/certgen.go b/certgen.go
index bbc45a4..52e2d9c 100644
--- a/certgen.go
+++ b/certgen.go
@@ -61,7 +61,7 @@ func NewTLSCertPair(organization string, validUntil time.Time, extraHosts []stri
 
 	addIP := func(ipAddr net.IP) {
 		for _, ip := range ipAddresses {
-			if bytes.Equal(ip, ipAddr) {
+			if ip.Equal(ipAddr) {
 				return
 			}
 		}
diff --git a/coinset/coins_test.go b/coinset/coins_test.go
index d8ca496..dc02d9f 100644
--- a/coinset/coins_test.go
+++ b/coinset/coins_test.go
@@ -33,7 +33,7 @@ func (c *TestCoin) ValueAge() int64       { return int64(c.TxValue) * c.TxNumCon
 
 func NewCoin(index int64, value btcutil.Amount, numConfs int64) coinset.Coin {
 	h := sha256.New()
-	h.Write([]byte(fmt.Sprintf("%d", index)))
+	_, _ = h.Write([]byte(fmt.Sprintf("%d", index)))
 	hash, _ := chainhash.NewHash(h.Sum(nil))
 	c := &TestCoin{
 		TxHash:     hash,
diff --git a/gcs/builder/builder.go b/gcs/builder/builder.go
index adef5c9..8b45d78 100644
--- a/gcs/builder/builder.go
+++ b/gcs/builder/builder.go
@@ -54,7 +54,7 @@ func RandomKey() ([gcs.KeySize]byte, error) {
 	}
 
 	// Copy the byte slice to a [gcs.KeySize]byte array and return it.
-	copy(key[:], randKey[:])
+	copy(key[:], randKey)
 	return key, nil
 }
 
@@ -62,7 +62,7 @@ func RandomKey() ([gcs.KeySize]byte, error) {
 // truncating the bytes of the hash to the appopriate key size.
 func DeriveKey(keyHash *chainhash.Hash) [gcs.KeySize]byte {
 	var key [gcs.KeySize]byte
-	copy(key[:], keyHash.CloneBytes()[:])
+	copy(key[:], keyHash.CloneBytes())
 	return key
 }
 
diff --git a/gcs/builder/builder_test.go b/gcs/builder/builder_test.go
index 8e9566f..de04421 100644
--- a/gcs/builder/builder_test.go
+++ b/gcs/builder/builder_test.go
@@ -19,9 +19,6 @@ import (
 )
 
 var (
-	// No need to allocate an err variable in every test
-	err error
-
 	// List of values for building a filter
 	contents = [][]byte{
 		[]byte("Alex"),
diff --git a/gcs/gcs.go b/gcs/gcs.go
index cfe215c..fbffb06 100644
--- a/gcs/gcs.go
+++ b/gcs/gcs.go
@@ -91,7 +91,7 @@ type Filter struct {
 // BuildGCSFilter builds a new GCS filter with the collision probability of
 // `1/(2**P)`, key `key`, and including every `[]byte` in `data` as a member of
 // the set.
-func BuildGCSFilter(P uint8, M uint64, key [KeySize]byte, data [][]byte) (*Filter, error) {
+func BuildGCSFilter(P uint8, M uint64, key [KeySize]byte, data [][]byte) (*Filter, error) { // nolint:gocritic
 	// Some initial parameter checks: make sure we have data from which to
 	// build the filter, and make sure our parameters will fit the hash
 	// function we're using.
@@ -174,7 +174,7 @@ func BuildGCSFilter(P uint8, M uint64, key [KeySize]byte, data [][]byte) (*Filte
 
 // FromBytes deserializes a GCS filter from a known N, P, and serialized filter
 // as returned by Bytes().
-func FromBytes(N uint32, P uint8, M uint64, d []byte) (*Filter, error) {
+func FromBytes(N uint32, P uint8, M uint64, d []byte) (*Filter, error) { // nolint:gocritic
 	// Basic sanity check.
 	if P > 32 {
 		return nil, ErrPTooBig
@@ -200,7 +200,7 @@ func FromBytes(N uint32, P uint8, M uint64, d []byte) (*Filter, error) {
 
 // FromNBytes deserializes a GCS filter from a known P, and serialized N and
 // filter as returned by NBytes().
-func FromNBytes(P uint8, M uint64, d []byte) (*Filter, error) {
+func FromNBytes(P uint8, M uint64, d []byte) (*Filter, error) { // nolint:gocritic
 	buffer := bytes.NewBuffer(d)
 	N, err := wire.ReadVarInt(buffer, varIntProtoVer)
 	if err != nil {
diff --git a/gcs/gcs_test.go b/gcs/gcs_test.go
index 369b773..bb4d550 100644
--- a/gcs/gcs_test.go
+++ b/gcs/gcs_test.go
@@ -27,7 +27,7 @@ var (
 	// Filters are conserved between tests but we must define with an
 	// interface which functions we're testing because the gcsFilter type
 	// isn't exported
-	filter, filter2, filter3, filter4, filter5 *gcs.Filter
+	filter, filter2, filter3 *gcs.Filter
 
 	// We need to use the same key for building and querying the filters
 	key [gcs.KeySize]byte
@@ -328,6 +328,8 @@ func TestGCSFilterMatchAnySuite(t *testing.T) {
 	}
 
 	for _, test := range funcs {
+		test := test
+
 		t.Run(test.name, func(t *testing.T) {
 			contentsCopy := make([][]byte, len(contents2))
 			copy(contentsCopy, contents2)
diff --git a/gcs/gcsbench_test.go b/gcs/gcsbench_test.go
index 58795eb..ffb2599 100644
--- a/gcs/gcsbench_test.go
+++ b/gcs/gcsbench_test.go
@@ -28,7 +28,6 @@ func genRandFilterElements(numElements uint) ([][]byte, error) {
 
 var (
 	generatedFilter *gcs.Filter
-	filterErr       error
 )
 
 // BenchmarkGCSFilterBuild benchmarks building a filter.
@@ -101,7 +100,7 @@ func BenchmarkGCSFilterMatch(b *testing.B) {
 
 	var localMatch bool
 	for i := 0; i < b.N; i++ {
-		localMatch, err = filter.Match(key, []byte("Nate"))
+		_, err = filter.Match(key, []byte("Nate"))
 		if err != nil {
 			b.Fatalf("unable to match filter: %v", err)
 		}
@@ -115,8 +114,6 @@ func BenchmarkGCSFilterMatch(b *testing.B) {
 }
 
 var (
-	randElems1, _        = genRandFilterElements(1)
-	randElems10, _       = genRandFilterElements(10)
 	randElems100, _      = genRandFilterElements(100)
 	randElems1000, _     = genRandFilterElements(1000)
 	randElems10000, _    = genRandFilterElements(10000)
@@ -164,6 +161,8 @@ var matchAnyBenchmarks = []struct {
 // BenchmarkGCSFilterMatchAny benchmarks the sort-and-zip MatchAny impl.
 func BenchmarkGCSFilterZipMatchAny(b *testing.B) {
 	for _, test := range matchAnyBenchmarks {
+		test := test
+
 		b.Run(test.name, func(b *testing.B) {
 			b.ReportAllocs()
 
@@ -188,6 +187,8 @@ func BenchmarkGCSFilterZipMatchAny(b *testing.B) {
 // BenchmarkGCSFilterMatchAny benchmarks the hash-join MatchAny impl.
 func BenchmarkGCSFilterHashMatchAny(b *testing.B) {
 	for _, test := range matchAnyBenchmarks {
+		test := test
+
 		b.Run(test.name, func(b *testing.B) {
 			b.ReportAllocs()
 
@@ -212,6 +213,8 @@ func BenchmarkGCSFilterHashMatchAny(b *testing.B) {
 // BenchmarkGCSFilterMatchAny benchmarks the hybrid MatchAny impl.
 func BenchmarkGCSFilterMatchAny(b *testing.B) {
 	for _, test := range matchAnyBenchmarks {
+		test := test
+
 		b.Run(test.name, func(b *testing.B) {
 			b.ReportAllocs()
 
diff --git a/hash160.go b/hash160.go
index 599a0fe..fa26e09 100644
--- a/hash160.go
+++ b/hash160.go
@@ -13,7 +13,7 @@ import (
 
 // Calculate the hash of hasher over buf.
 func calcHash(buf []byte, hasher hash.Hash) []byte {
-	hasher.Write(buf)
+	_, _ = hasher.Write(buf)
 	return hasher.Sum(nil)
 }
 
diff --git a/hdkeychain/bench_test.go b/hdkeychain/bench_test.go
index 583eef0..7c86ca9 100644
--- a/hdkeychain/bench_test.go
+++ b/hdkeychain/bench_test.go
@@ -26,7 +26,7 @@ func BenchmarkDeriveHardened(b *testing.B) {
 	b.StartTimer()
 
 	for i := 0; i < b.N; i++ {
-		masterKey.Derive(hdkeychain.HardenedKeyStart)
+		_, _ = masterKey.Derive(hdkeychain.HardenedKeyStart)
 	}
 }
 
@@ -41,7 +41,7 @@ func BenchmarkDeriveNormal(b *testing.B) {
 	b.StartTimer()
 
 	for i := 0; i < b.N; i++ {
-		masterKey.Derive(0)
+		_, _ = masterKey.Derive(0)
 	}
 }
 
@@ -56,7 +56,7 @@ func BenchmarkPrivToPub(b *testing.B) {
 	b.StartTimer()
 
 	for i := 0; i < b.N; i++ {
-		masterKey.Neuter()
+		_, _ = masterKey.Neuter()
 	}
 }
 
@@ -64,7 +64,7 @@ func BenchmarkPrivToPub(b *testing.B) {
 // extended key.
 func BenchmarkDeserialize(b *testing.B) {
 	for i := 0; i < b.N; i++ {
-		hdkeychain.NewKeyFromString(bip0032MasterPriv1)
+		_, _ = hdkeychain.NewKeyFromString(bip0032MasterPriv1)
 	}
 }
 
diff --git a/hdkeychain/extendedkey.go b/hdkeychain/extendedkey.go
index a0c5e7b..929fe99 100644
--- a/hdkeychain/extendedkey.go
+++ b/hdkeychain/extendedkey.go
@@ -277,7 +277,7 @@ func (k *ExtendedKey) Derive(i uint32) (*ExtendedKey, error) {
 	// data:
 	//   I = HMAC-SHA512(Key = chainCode, Data = data)
 	hmac512 := hmac.New(sha512.New, k.chainCode)
-	hmac512.Write(data)
+	_, _ = hmac512.Write(data)
 	ilr := hmac512.Sum(nil)
 
 	// Split "I" into two 32-byte sequences Il and Ir where:
@@ -380,7 +380,7 @@ func (k *ExtendedKey) DeriveNonStandard(i uint32) (*ExtendedKey, error) {
 	binary.BigEndian.PutUint32(data[keyLen:], i)
 
 	hmac512 := hmac.New(sha512.New, k.chainCode)
-	hmac512.Write(data)
+	_, _ = hmac512.Write(data)
 	ilr := hmac512.Sum(nil)
 
 	il := ilr[:len(ilr)/2]
@@ -610,7 +610,7 @@ func NewMaster(seed []byte, net *chaincfg.Params) (*ExtendedKey, error) {
 	// First take the HMAC-SHA512 of the master key and the seed data:
 	//   I = HMAC-SHA512(Key = "Bitcoin seed", Data = S)
 	hmac512 := hmac.New(sha512.New, masterKey)
-	hmac512.Write(seed)
+	_, _ = hmac512.Write(seed)
 	lr := hmac512.Sum(nil)
 
 	// Split "I" into two 32-byte sequences Il and Ir where:
diff --git a/hdkeychain/extendedkey_test.go b/hdkeychain/extendedkey_test.go
index 37a42fa..dd6deb5 100644
--- a/hdkeychain/extendedkey_test.go
+++ b/hdkeychain/extendedkey_test.go
@@ -983,7 +983,7 @@ func TestZero(t *testing.T) {
 		wantAddr := "1HT7xU2Ngenf7D4yocz2SAcnNLW7rK8d4E"
 		addr, err := key.Address(&chaincfg.MainNetParams)
 		if err != nil {
-			t.Errorf("Addres s #%d (%s): unexpected error: %v", i,
+			t.Errorf("Address #%d (%s): unexpected error: %v", i,
 				testName, err)
 			return false
 		}
diff --git a/wif_test.go b/wif_test.go
index dec6dd6..589f2ac 100644
--- a/wif_test.go
+++ b/wif_test.go
@@ -64,6 +64,8 @@ func TestEncodeDecodeWIF(t *testing.T) {
 	}
 
 	for _, validCase := range validEncodeCases {
+		validCase := validCase
+
 		t.Run(validCase.name, func(t *testing.T) {
 			priv, _ := btcec.PrivKeyFromBytes(btcec.S256(), validCase.privateKey)
 			wif, err := NewWIF(priv, validCase.net, validCase.compress)
@@ -122,6 +124,8 @@ func TestEncodeDecodeWIF(t *testing.T) {
 	}
 
 	for _, invalidCase := range invalidDecodeCases {
+		invalidCase := invalidCase
+
 		t.Run(invalidCase.name, func(t *testing.T) {
 			decodedWif, err := DecodeWIF(invalidCase.wif)
 			if decodedWif != nil {