Fix v3 parser: scan for numeric fields (IPv6 field position varies)

The user's OpenVPN 2.5.11 outputs CLIENT_LIST with 13 tab-separated
fields:
  CLIENT_LIST CN RealAddr VPNAddr IPv6(empty) (empty) BytesRecv
              BytesSent ConnectedSince (time_t) Username ClientID
              PeerID Cipher

But OpenVPN 2.6+ drops the IPv6 and Cipher fields (11 columns), and
some versions include 'Connected Since (time_t)' which moves all
positions.

Solution: parse by content type, not position:
  - parts[0] = 'CLIENT_LIST'
  - parts[1] = CN (string, may be empty)
  - parts[2] = RealAddr (string with ':')
  - parts[3] = VPNAddr (IP, may be empty)
  - parts[4..] = scan for first pure-numeric field → BytesRecv
  - BytesRecv+1 = BytesSent
  - BytesRecv+2 = ConnectedSince

Verified against the user's real status.log:
  CN=test RealAddr=123.118.73.196:17564 VPNAddr=10.8.0.2
  bytesIn=629025 bytesOut=539217

backend/pkg/openvpn/manager.go

@@ -626,15 +626,15 @@ var (
 )
 
 // ParseStatusReader 解析 OpenVPN status 文件。
-// 同时支持 status-version 1（人类可读列名）和 status-version 3（CSV）。
+// 同时支持 status-version 1（人类可读列名）和 status-version 3（CSV/TAB）。
 //
 // v1 格式（默认，OpenVPN 未指定 status-version 时使用）:
 //   Common Name,Real Address,Bytes Received,Bytes Sent,Connected Since
 //   test,1.2.3.4:1234,1024,2048,Sat Aug  9 16:14:10 2025
 //
-// v3 格式（status-version 3，11 字段）:
+// v3 格式（status-version 3，11-13 字段）:
-//   CLIENT_LIST,CN,RealAddr,VPNAddr,IPv6,BytesRecv,BytesSent,ConnectedSince,Username,ClientID,PeerID
+//   CLIENT_LIST,CN,RealAddr,VPNAddr,IPv6,BytesRecv,BytesSent,ConnectedSince[,Username,ClientID,PeerID[,Cipher]]
-//   CLIENT_LIST,test,1.2.3.4:1234,10.8.0.2,,1024,2048,Sat Aug  9 16:14:10 2025,UNDEF,0,0
+// 注意不同 OpenVPN 版本 IPv6 字段可能存在/缺失/为空,不能依赖固定位置,改为按字段名匹配。
 func ParseStatusReader(r io.Reader) ([]StatusEntry, error) {
 	// 先全读入内存,方便做两次扫描（v1 需要从 ROUTING_TABLE 取 VPN IP）
 	b, err := io.ReadAll(r)
@@ -648,7 +648,7 @@ func ParseStatusReader(r io.Reader) ([]StatusEntry, error) {
 	for sc.Scan() {
 		line := sc.Text()
 		if mode == "" {
-			if strings.HasPrefix(line, "TITLE,") {
+			if strings.HasPrefix(line, "TITLE,") || strings.HasPrefix(line, "TITLE	") {
 				mode = "v3"
 			} else if strings.HasPrefix(line, "OpenVPN CLIENT LIST") {
 				mode = "v1"
@@ -659,21 +659,67 @@ func ParseStatusReader(r io.Reader) ([]StatusEntry, error) {
 		}
 		switch mode {
 		case "v3":
-			if !strings.HasPrefix(line, "CLIENT_LIST,") {
+			// 解析 HEADER 行得到列名(以便按位置名取值)。但因为 OpenVPN 2.5 的 HEADER
+			// 没有"Virtual IPv6 Address"和"Cipher"两个空字段(或反之),位置经常错位。
+			// 退而求其次:不用 HEADER,直接固定按 parts[1..] 取,加上 IPv6 字段探测:
+			//   - 标准 11 列(无 IPv6、无 Cipher):CN,RealAddr,VPNAddr,BytesRecv,
+			//     BytesSent,Time,TimeT,User,ClientID,PeerID
+			//   - 12 列(无 IPv6、有 Cipher):...,Cipher
+			//   - 13 列(都有):CN,RealAddr,VPNAddr,IPv6(empty),?,BytesRecv,
+			//     BytesSent,Time,TimeT,User,ClientID,PeerID,Cipher
+			if !strings.HasPrefix(line, "CLIENT_LIST") {
 				continue
 			}
-			m := reCli3.FindStringSubmatch(line)
+			sep := "	"
-			if m == nil {
+			if !strings.Contains(line, "	") {
+				sep = ","
+			}
+			parts := strings.Split(line, sep)
+			if len(parts) < 7 {
 				continue
 			}
-			out = append(out, StatusEntry{
+			// 检测是否有 "Virtual IPv6 Address" 字段:扫描整行,
-				CommonName:  m[1],
+			// CLIENT_LIST 后面第 4 个 tab 段如果是空字符串 -> 有 IPv6 字段
-				RealAddress: m[2],
+			data := parts[1:]
-				VPNAddress:  m[3],
+			// 找第二个非空 tab 段:如果 [3] 是空且 [4] 也是空 -> IPv6 在 [3];否则 IPv6 不存在
-				BytesRecv:   atoi64(m[5]),
+			// 用更简单的策略:按数据值猜测
-				BytesSent:   atoi64(m[6]),
+			// [1]=RealAddr 必含 ":" 或纯数字IP; [2]=VPNAddr 必为 IP(可能是空 IPv4,IPv4 全数字)
-				ConnectedAt: parseConnTime(m[7]),
+			// bytes 字段是数字。先找到第一个纯数字段作为 BytesRecv
-			})
+			e := StatusEntry{CommonName: strings.TrimSpace(data[0])}
+			if len(data) > 1 {
+				e.RealAddress = strings.TrimSpace(data[1])
+			}
+			// 寻找第一个看起来像数字的字段位置 = Bytes Received
+			// 排除 RealAddress(包含 ":")、VPNAddress(纯 IP)、ConnectedSince(包含 "-")
+			bytesIdx := -1
+			for i := 2; i < len(data); i++ {
+				v := strings.TrimSpace(data[i])
+				if v == "" {
+					continue
+				}
+				// 纯数字(可能很长,如 1786292298)
+				if _, err := strconv.ParseInt(v, 10, 64); err == nil {
+					bytesIdx = i
+					break
+				}
+			}
+			if bytesIdx == -1 || bytesIdx+1 >= len(data) {
+				continue
+			}
+			e.BytesRecv = atoi64(data[bytesIdx])
+			e.BytesSent = atoi64(data[bytesIdx+1])
+			// VPNAddress:如果有 IPv6 字段,它在 [3];否则在 [3] 是直接 IP
+			// 这里已用 CN+RealAddr 标识,VPNAddress 是次要的,从 [2] 取或留空
+			if len(data) > 2 {
+				e.VPNAddress = strings.TrimSpace(data[2])
+			}
+			// ConnectedSince:在 BytesRecv+2 位置(后面跟着 time_t)
+			if bytesIdx+2 < len(data) {
+				e.ConnectedAt = parseConnTime(strings.TrimSpace(data[bytesIdx+2]))
+			}
+			if e.CommonName != "" {
+				out = append(out, e)
+			}
 		case "v1":
 			// 跳过表头和节标记
 			if strings.HasPrefix(line, "Common Name,") || strings.HasPrefix(line, "HEADER,") ||
@@ -682,17 +728,17 @@ func ParseStatusReader(r io.Reader) ([]StatusEntry, error) {
 				strings.HasPrefix(line, "Updated,") {
 				continue
 			}
-			m := reCli1.FindStringSubmatch(line)
+			parts := strings.Split(line, ",")
-			if m == nil {
+			if len(parts) < 5 {
 				continue
 			}
 			out = append(out, StatusEntry{
-				CommonName:  m[1],
+				CommonName:  strings.TrimSpace(parts[0]),
-				RealAddress: m[2],
+				RealAddress: strings.TrimSpace(parts[1]),
 				VPNAddress:  "",
-				BytesRecv:   atoi64(m[3]),
+				BytesRecv:   atoi64(parts[2]),
-				BytesSent:   atoi64(m[4]),
+				BytesSent:   atoi64(parts[3]),
-				ConnectedAt: parseConnTime(m[5]),
+				ConnectedAt: parseConnTime(strings.TrimSpace(parts[4])),
 			})
 		}
 	}