Initial commit

dnsfilter/helpers.go

@@ -0,0 +1,81 @@
+package dnsfilter
+
+import (
+	"fmt"
+	"path"
+	"runtime"
+	"strings"
+	"sync/atomic"
+)
+
+func isValidRule(rule string) bool {
+	if len(rule) < 4 {
+		return false
+	}
+	if rule[0] == '!' {
+		return false
+	}
+	if rule[0] == '#' {
+		return false
+	}
+	if strings.HasPrefix(rule, "[Adblock") {
+		return false
+	}
+
+	masks := []string{
+		"##",
+		"#@#",
+		"#$#",
+		"#@$#",
+		"$$",
+		"$@$",
+		"#%#",
+		"#@%#",
+	}
+	for _, mask := range masks {
+		if strings.Contains(rule, mask) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func updateMax(valuePtr *int64, maxPtr *int64) {
+	for {
+		current := atomic.LoadInt64(valuePtr)
+		max := atomic.LoadInt64(maxPtr)
+		if current <= max {
+			break
+		}
+		swapped := atomic.CompareAndSwapInt64(maxPtr, max, current)
+		if swapped == true {
+			break
+		}
+		// swapping failed because value has changed after reading, try again
+	}
+}
+
+//
+// helper functions for debugging and testing
+//
+func _Func() string {
+	pc := make([]uintptr, 10) // at least 1 entry needed
+	runtime.Callers(2, pc)
+	f := runtime.FuncForPC(pc[0])
+	return path.Base(f.Name())
+}
+
+func trace(format string, args ...interface{}) {
+	pc := make([]uintptr, 10) // at least 1 entry needed
+	runtime.Callers(2, pc)
+	f := runtime.FuncForPC(pc[0])
+	var buf strings.Builder
+	buf.WriteString(fmt.Sprintf("%s(): ", path.Base(f.Name())))
+	text := fmt.Sprintf(format, args...)
+	buf.WriteString(text)
+	if len(text) == 0 || text[len(text)-1] != '\n' {
+		buf.WriteRune('\n')
+	}
+	fmt.Print(buf.String())
+}