From b0304876a817d7e59901bdc8a2a753b6dc73320d Mon Sep 17 00:00:00 2001
From: sagit <sagitchu@gmail.com>
Date: Sun, 8 Feb 2026 06:00:48 +0000
Subject: [PATCH] fix: implement random port assignment with conflict check for
 forward creation

---
 go-backend/internal/http/handler/mutations.go | 132 +++++++++++++++---
 1 file changed, 116 insertions(+), 16 deletions(-)

diff --git a/go-backend/internal/http/handler/mutations.go b/go-backend/internal/http/handler/mutations.go
index 0b2262b..f04177d 100644
--- a/go-backend/internal/http/handler/mutations.go
+++ b/go-backend/internal/http/handler/mutations.go
@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math/big"
 	"net"
 	"net/http"
 	"sort"
@@ -2399,30 +2400,129 @@ func (h *Handler) tunnelEntryNodeIDs(tunnelID int64) ([]int64, error) {
 }
 
 func (h *Handler) pickTunnelPort(tunnelID int64) int {
-	entry, _ := h.tunnelEntryNodeIDs(tunnelID)
-	if len(entry) == 0 {
+	entryNodes, err := h.tunnelEntryNodeIDs(tunnelID)
+	if err != nil || len(entryNodes) == 0 {
 		return 10000
 	}
-	var portRange string
-	_ = h.repo.DB().QueryRow(`SELECT port FROM node WHERE id = ?`, entry[0]).Scan(&portRange)
-	if portRange == "" {
-		return 10000
-	}
-	first := strings.Split(portRange, ",")[0]
-	first = strings.TrimSpace(first)
-	if strings.Contains(first, "-") {
-		parts := strings.SplitN(first, "-", 2)
-		p, _ := strconv.Atoi(strings.TrimSpace(parts[0]))
-		if p > 0 {
-			return p
+
+	var commonAvailable []int
+	firstNode := true
+
+	for _, nodeID := range entryNodes {
+		var portRange string
+		if err := h.repo.DB().QueryRow("SELECT port FROM node WHERE id = ?", nodeID).Scan(&portRange); err != nil {
+			continue
+		}
+		if portRange == "" {
+			portRange = "1000-65535"
+		}
+
+		nodePorts, err := parsePorts(portRange)
+		if err != nil {
+			continue
+		}
+
+		used, err := h.getUsedPorts(nodeID)
+		if err != nil {
+			continue
+		}
+
+		var available []int
+		for _, p := range nodePorts {
+			if !used[p] {
+				available = append(available, p)
+			}
+		}
+
+		if firstNode {
+			commonAvailable = available
+			firstNode = false
+		} else {
+			set := make(map[int]bool)
+			for _, p := range available {
+				set[p] = true
+			}
+			var newCommon []int
+			for _, p := range commonAvailable {
+				if set[p] {
+					newCommon = append(newCommon, p)
+				}
+			}
+			commonAvailable = newCommon
+		}
+
+		if len(commonAvailable) == 0 {
+			break
 		}
 	}
-	if p, err := strconv.Atoi(first); err == nil && p > 0 {
-		return p
+
+	if len(commonAvailable) > 0 {
+		idx, _ := rand.Int(rand.Reader, big.NewInt(int64(len(commonAvailable))))
+		return commonAvailable[idx.Int64()]
 	}
+
 	return 10000
 }
 
+func (h *Handler) getUsedPorts(nodeID int64) (map[int]bool, error) {
+	used := make(map[int]bool)
+	rows, err := h.repo.DB().Query("SELECT port FROM forward_port WHERE node_id = ?", nodeID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var p int
+		if err := rows.Scan(&p); err == nil {
+			used[p] = true
+		}
+	}
+	rows2, err := h.repo.DB().Query("SELECT port FROM chain_tunnel WHERE node_id = ? AND port > 0", nodeID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows2.Close()
+	for rows2.Next() {
+		var p int
+		if err := rows2.Scan(&p); err == nil {
+			used[p] = true
+		}
+	}
+	return used, nil
+}
+
+func parsePorts(portRange string) ([]int, error) {
+	var ports []int
+	parts := strings.Split(portRange, ",")
+	for _, part := range parts {
+		part = strings.TrimSpace(part)
+		if part == "" {
+			continue
+		}
+		if strings.Contains(part, "-") {
+			rangeParts := strings.Split(part, "-")
+			if len(rangeParts) != 2 {
+				return nil, errors.New("invalid port range format")
+			}
+			start, err1 := strconv.Atoi(strings.TrimSpace(rangeParts[0]))
+			end, err2 := strconv.Atoi(strings.TrimSpace(rangeParts[1]))
+			if err1 != nil || err2 != nil || start > end {
+				return nil, errors.New("invalid port range values")
+			}
+			for i := start; i <= end; i++ {
+				ports = append(ports, i)
+			}
+		} else {
+			p, err := strconv.Atoi(part)
+			if err != nil {
+				return nil, errors.New("invalid port value")
+			}
+			ports = append(ports, p)
+		}
+	}
+	return ports, nil
+}
+
 func (h *Handler) replaceForwardPorts(forwardID, tunnelID int64, port int) error {
 	tx, err := h.repo.DB().Begin()
 	if err != nil {