all: improve linters config and fix some warnings

.golangci.yml

@@ -4,7 +4,7 @@ linters-settings:
   golint:
     min-confidence: 0
   gocyclo:
-    min-complexity: 10
+    min-complexity: 15
   maligned:
     suggest-new: true
   dupl:
@@ -23,29 +23,35 @@ linters-settings:
   lll:
     line-length: 140
   goimports:
-    local-prefixes: github.com/golangci/golangci-lint
+    local-prefixes: github.com/gortc
   gocritic:
     enabled-tags:
       - performance
       - style
       - experimental
     disabled-checks:
-      - wrapperFunc
-      - commentFormatting # https://github.com/go-critic/go-critic/issues/755
+      - sloppyReassign
 
 issues:
+  exclude:
+    - "`assertHMACSize` - `blocksize` always receives `64`"
   exclude-rules:
+    - text: "string `<nil>`"
+      linters:
+        - goconst
+
     # Exclude some linters from running on tests files.
     - path: _test\.go
       linters:
         - gocyclo
         - errcheck
         - dupl
         - gosec
+        - goconst
 
     # Ease some gocritic warnings on test files.
     - path: _test\.go
-      text: "(unnamedResult|exitAfterDefer)"
+      text: "(unnamedResult|exitAfterDefer|unlambda)"
       linters:
         - gocritic
 
@@ -65,10 +71,26 @@ issues:
       linters:
         - gosec
         - errcheck
+        - unparam
+
+    - path: ^cmd/
+      linters:
+        - gocyclo
+    - path: ^cmd/
+      text: "(unnamedResult|exitAfterDefer)"
+      linters:
+        - gocritic
+    - path: ^message.go$
+      text: "commentedOutCode"
+      linters:
+        - gocritic
+
+linters:
   enable-all: true
   disable:
     - prealloc
     - gochecknoglobals
+    - scopelint
 
 run:
   skip-dirs:

client.go

@@ -230,7 +230,7 @@ func putClientTransaction(t *clientTransaction) {
 	clientTransactionPool.Put(t)
 }
 
-func (t clientTransaction) nextTimeout(now time.Time) time.Time {
+func (t *clientTransaction) nextTimeout(now time.Time) time.Time {
 	return now.Add(time.Duration(t.attempt+1) * t.rto)
 }
 

cmd/stun-client/stun-client.go

@@ -16,7 +16,7 @@ func main() {
 	}
 	flag.Parse()
 	addr := flag.Arg(0)
-	if len(addr) == 0 {
+	if addr == "" {
 		addr = "stun.l.google.com:19302"
 	}
 	c, err := stun.Dial("udp", addr)

fingerprint_test.go

@@ -33,7 +33,7 @@ func TestFingerprint_Check(t *testing.T) {
 	if err := Fingerprint.Check(m); err != nil {
 		t.Error(err)
 	}
-	m.Raw[3] = m.Raw[3] + 1
+	m.Raw[3]++
 	if err := Fingerprint.Check(m); err == nil {
 		t.Error("should error")
 	}