add group fwmark and table using

group.go

@@ -0,0 +1,9 @@
+package main
+
+import "kvas2-go/models"
+
+type Group struct {
+	*models.Group
+	FWMark uint32
+	Table  uint16
+}

kvas2.go

@@ -2,12 +2,20 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
-	"kvas2-go/models"
-	"kvas2-go/pkg/dns-proxy"
-	"kvas2-go/pkg/iptables-helper"
+	"strconv"
 	"sync"
 	"time"
+
+	"kvas2-go/models"
+	"kvas2-go/pkg/dns-proxy"
+	"kvas2-go/pkg/ip-helper"
+	"kvas2-go/pkg/iptables-helper"
+)
+
+var (
+	ErrGroupIDConflict = errors.New("group id conflict")
 )
 
 type Config struct {
@@ -23,7 +31,7 @@ type App struct {
 	DNSProxy     *dnsProxy.DNSProxy
 	DNSOverrider *iptablesHelper.DNSOverrider
 	Records      *Records
-	Groups       []*models.Group
+	Groups       map[int]Group
 }
 
 func (a *App) Listen(ctx context.Context) []error {
@@ -76,6 +84,38 @@ func (a *App) Listen(ctx context.Context) []error {
 	return errs
 }
 
+func (a *App) AppendGroup(group *models.Group) error {
+	if _, exists := a.Groups[group.ID]; exists {
+		return ErrGroupIDConflict
+	}
+
+	fwmark, err := ipHelper.GetUnusedFwMark()
+	if err != nil {
+		return fmt.Errorf("error while getting fwmark: %w", err)
+	}
+
+	table, err := ipHelper.GetUnusedTable()
+	if err != nil {
+		return fmt.Errorf("error while getting table: %w", err)
+	}
+
+	out, err := ipHelper.ExecIp("rule", "add", "fwmark", strconv.Itoa(int(fwmark)), "table", strconv.Itoa(int(table)))
+	if err != nil {
+		return err
+	}
+	if len(out) != 0 {
+		return errors.New(string(out))
+	}
+
+	a.Groups[group.ID] = Group{
+		Group:  group,
+		FWMark: fwmark,
+		Table:  table,
+	}
+
+	return nil
+}
+
 func (a *App) processARecord(aRecord dnsProxy.Address) {
 	ttlDuration := time.Duration(aRecord.TTL) * time.Second
 	if ttlDuration < a.Config.MinimalTTL {
@@ -169,7 +209,7 @@ func New(config Config) (*App, error) {
 		return nil, fmt.Errorf("failed to initialize DNS overrider: %w", err)
 	}
 
-	app.Groups = make([]*models.Group, 0)
+	app.Groups = make(map[int]Group)
 
 	return app, nil
 }

pkg/ip-helper/ip-helper.go

@@ -3,15 +3,22 @@ package ipHelper
 import (
 	"bufio"
 	"bytes"
+	"errors"
 	"fmt"
 	"os"
 	"os/exec"
 	"regexp"
+	"slices"
 	"strconv"
 	"strings"
 )
 
-func execIp(args ...string) ([]byte, error) {
+var (
+	ErrMaxTableSize  = errors.New("max table size")
+	ErrMaxFwMarkSize = errors.New("max fwmark size")
+)
+
+func ExecIp(args ...string) ([]byte, error) {
 	cmd := exec.Command("ip", args...)
 	var out bytes.Buffer
 	cmd.Stdout = &out
@@ -22,10 +29,10 @@ func execIp(args ...string) ([]byte, error) {
 	return out.Bytes(), nil
 }
 
-func GetUsedFwMarks() ([]int, error) {
-	markMap := make(map[int]struct{})
+func GetUsedFwMarks() ([]uint32, error) {
+	markMap := make(map[uint32]struct{})
 
-	out, err := execIp("rule", "show")
+	out, err := ExecIp("rule", "show")
 	if err != nil {
 		return nil, fmt.Errorf("error while getting rules: %w", err)
 	}
@@ -40,11 +47,11 @@ func GetUsedFwMarks() ([]int, error) {
 		hexStr := match[1]
 		hexValue, err := strconv.ParseInt(hexStr, 16, 64)
 		if err == nil {
-			markMap[int(hexValue)] = struct{}{}
+			markMap[uint32(hexValue)] = struct{}{}
 		}
 	}
 
-	marks := make([]int, len(markMap))
+	marks := make([]uint32, len(markMap))
 	counter := 0
 	for mark, _ := range markMap {
 		marks[counter] = mark
@@ -54,8 +61,24 @@ func GetUsedFwMarks() ([]int, error) {
 	return marks, nil
 }
 
-func GetTableAliases() (map[string]int, error) {
-	tables := map[string]int{
+func GetUnusedFwMark() (uint32, error) {
+	usedFwMarks, err := GetUsedFwMarks()
+	if err != nil {
+		return 0, fmt.Errorf("error while getting used fwmarks: %w", err)
+	}
+
+	fwmark := uint32(1)
+	for slices.Contains(usedFwMarks, fwmark) {
+		fwmark++
+		if fwmark == 0xFFFFFFFF {
+			return 0, ErrMaxFwMarkSize
+		}
+	}
+	return fwmark, nil
+}
+
+func GetTableAliases() (map[string]uint16, error) {
+	tables := map[string]uint16{
 		"unspec":  0,
 		"default": 253,
 		"main":    254,
@@ -82,7 +105,7 @@ func GetTableAliases() (map[string]int, error) {
 		if len(parts) >= 2 {
 			tableID, err := strconv.Atoi(parts[0])
 			if err == nil {
-				tables[parts[1]] = tableID
+				tables[parts[1]] = uint16(tableID)
 			}
 		}
 	}
@@ -94,8 +117,8 @@ func GetTableAliases() (map[string]int, error) {
 	return tables, nil
 }
 
-func GetUsedTables() ([]int, error) {
-	tableMap := map[int]struct{}{
+func GetUsedTables() ([]uint16, error) {
+	tableMap := map[uint16]struct{}{
 		0:   {},
 		253: {},
 		254: {},
@@ -107,7 +130,7 @@ func GetUsedTables() ([]int, error) {
 		return nil, fmt.Errorf("error while getting table aliases: %w", err)
 	}
 
-	out, err := execIp("route", "show", "table", "all")
+	out, err := ExecIp("route", "show", "table", "all")
 	if err != nil {
 		return nil, fmt.Errorf("error while getting routes: %w", err)
 	}
@@ -119,7 +142,8 @@ func GetUsedTables() ([]int, error) {
 				if part == "table" && i+1 < len(parts) {
 					tableNum, ok := tableAliases[parts[i+1]]
 					if !ok {
-						tableNum, _ = strconv.Atoi(parts[i+1])
+						tableNumInt, _ := strconv.Atoi(parts[i+1])
+						tableNum = uint16(tableNumInt)
 					}
 					tableMap[tableNum] = struct{}{}
 				}
@@ -127,7 +151,28 @@ func GetUsedTables() ([]int, error) {
 		}
 	}
 
-	tables := make([]int, len(tableMap))
+	out, err = ExecIp("rule", "show")
+	if err != nil {
+		return nil, fmt.Errorf("error while getting rules: %w", err)
+	}
+
+	for _, line := range strings.Split(string(out), "\n") {
+		if strings.Contains(line, "lookup") {
+			parts := strings.Fields(line)
+			for i, part := range parts {
+				if part == "lookup" && i+1 < len(parts) {
+					tableNum, ok := tableAliases[parts[i+1]]
+					if !ok {
+						tableNumInt, _ := strconv.Atoi(parts[i+1])
+						tableNum = uint16(tableNumInt)
+					}
+					tableMap[tableNum] = struct{}{}
+				}
+			}
+		}
+	}
+
+	tables := make([]uint16, len(tableMap))
 	counter := 0
 	for table, _ := range tableMap {
 		tables[counter] = table
@@ -136,3 +181,19 @@ func GetUsedTables() ([]int, error) {
 
 	return tables, nil
 }
+
+func GetUnusedTable() (uint16, error) {
+	usedTables, err := GetUsedTables()
+	if err != nil {
+		return 0, fmt.Errorf("error while getting used tables: %w", err)
+	}
+
+	tableID := uint16(1)
+	for slices.Contains(usedTables, tableID) {
+		tableID++
+		if tableID > 0x3FF {
+			return 0, ErrMaxTableSize
+		}
+	}
+	return tableID, nil
+}