ipHelper

ip-helper/ip-helper.go

@@ -0,0 +1,138 @@
+package ipHelper
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+func execIp(args ...string) ([]byte, error) {
+	cmd := exec.Command("ip", args...)
+	var out bytes.Buffer
+	cmd.Stdout = &out
+	err := cmd.Run()
+	if err != nil {
+		return nil, err
+	}
+	return out.Bytes(), nil
+}
+
+func GetUsedFwMarks() ([]int, error) {
+	markMap := make(map[int]struct{})
+
+	out, err := execIp("rule", "show")
+	if err != nil {
+		return nil, fmt.Errorf("error while getting rules: %w", err)
+	}
+
+	re := regexp.MustCompile(`fwmark\s+0x([0-9a-fA-F]+)`)
+	for _, line := range strings.Split(string(out), "\n") {
+		match := re.FindStringSubmatch(line)
+		if len(match) < 2 {
+			continue
+		}
+
+		hexStr := match[1]
+		hexValue, err := strconv.ParseInt(hexStr, 16, 64)
+		if err == nil {
+			markMap[int(hexValue)] = struct{}{}
+		}
+	}
+
+	marks := make([]int, len(markMap))
+	counter := 0
+	for mark, _ := range markMap {
+		marks[counter] = mark
+		counter++
+	}
+
+	return marks, nil
+}
+
+func GetTableAliases() (map[string]int, error) {
+	tables := map[string]int{
+		"unspec":  0,
+		"default": 253,
+		"main":    254,
+		"local":   255,
+	}
+
+	file, err := os.Open("/opt/etc/iproute2/rt_tables")
+	if err != nil {
+		if os.IsNotExist(err) {
+			return tables, nil
+		}
+		return nil, err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasPrefix(line, "#") || len(strings.TrimSpace(line)) == 0 {
+			continue
+		}
+
+		parts := strings.Fields(line)
+		if len(parts) >= 2 {
+			tableID, err := strconv.Atoi(parts[0])
+			if err == nil {
+				tables[parts[1]] = tableID
+			}
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return tables, nil
+}
+
+func GetUsedTables() ([]int, error) {
+	tableMap := map[int]struct{}{
+		0:   {},
+		253: {},
+		254: {},
+		255: {},
+	}
+
+	tableAliases, err := GetTableAliases()
+	if err != nil {
+		return nil, fmt.Errorf("error while getting table aliases: %w", err)
+	}
+
+	out, err := execIp("route", "show", "table", "all")
+	if err != nil {
+		return nil, fmt.Errorf("error while getting routes: %w", err)
+	}
+
+	for _, line := range strings.Split(string(out), "\n") {
+		if strings.Contains(line, "table") {
+			parts := strings.Fields(line)
+			for i, part := range parts {
+				if part == "table" && i+1 < len(parts) {
+					tableNum, ok := tableAliases[parts[i+1]]
+					if !ok {
+						tableNum, _ = strconv.Atoi(parts[i+1])
+					}
+					tableMap[tableNum] = struct{}{}
+				}
+			}
+		}
+	}
+
+	tables := make([]int, len(tableMap))
+	counter := 0
+	for table, _ := range tableMap {
+		tables[counter] = table
+		counter++
+	}
+
+	return tables, nil
+}