fix: CDN优选IP支持IPv6、格式校验及错误降级

- replaceHost() 自动为裸 IPv6 地址包裹方括号，修复 IPv6 URL 畸形问题
- 新增 ValidateServerIPs() 校验 IP 格式，保存配置时拦截非法输入
- GetServerIPList() 运行时自动过滤非法 IP 条目
- CDN IP 尝试时 TLS/认证错误降级为非致命，跳过该 IP 继续故障转移
  而非终止整个连接循环（仅原始域名 ipIndex==0 时才判为致命）
- 占位符提示支持 IPv4/IPv6

internal/i18n/en.toml

@@ -45,6 +45,7 @@ DlgDeleteProfileMsg = 'Delete profile "{{.name}}" and its stored credentials?'
 DlgProfileTitle = "Profile"
 DlgValidationTitle = "Validation"
 DlgValidationMsg = "Name, Host, and Username are required."
+DlgInvalidIPMsg = "Invalid IP address(es): {{.ips}}"
 DlgDaemonError = "Daemon Error"
 DlgCredentialError = "Credential Error"
 DlgCredentialErrorMsg = "No password stored for this profile. Edit the profile to set it."
@@ -93,7 +94,7 @@ FieldMTUOverride = "MTU Override"
 PlaceholderCIDRs = "10.0.0.0/8, 172.16.0.0/12"
 PlaceholderMTU = "0 = use server MTU"
 PlaceholderPasswordUnchanged = "(unchanged)"
-PlaceholderServerIPs = "e.g. 1.2.3.4, 5.6.7.8"
+PlaceholderServerIPs = "IPv4/IPv6 supported, e.g. 1.2.3.4, 5.6.7.8"
 
 AuthModeBoth = "Both (JWT + Password)"
 AuthModeJWT = "JWT"

internal/i18n/zh-Hans.toml

@@ -45,6 +45,7 @@ DlgDeleteProfileMsg = '删除配置"{{.name}}"及其存储的凭据？'
 DlgProfileTitle = "配置"
 DlgValidationTitle = "验证"
 DlgValidationMsg = "名称、主机名和用户名为必填项。"
+DlgInvalidIPMsg = "以下 IP 地址格式无效：{{.ips}}"
 DlgDaemonError = "守护进程错误"
 DlgCredentialError = "凭据错误"
 DlgCredentialErrorMsg = "此配置未存储密码。请编辑配置以设置密码。"
@@ -93,7 +94,7 @@ FieldMTUOverride = "MTU 覆盖"
 PlaceholderCIDRs = "10.0.0.0/8, 172.16.0.0/12"
 PlaceholderMTU = "0 = 使用服务器 MTU"
 PlaceholderPasswordUnchanged = "（未更改）"
-PlaceholderServerIPs = "例: 1.2.3.4, 5.6.7.8"
+PlaceholderServerIPs = "支持 IPv4/IPv6，例: 1.2.3.4, 5.6.7.8"
 
 AuthModeBoth = "全部（JWT + 密码）"
 AuthModeJWT = "JWT"

internal/model/model.go

@@ -4,6 +4,7 @@ package model
 
 import (
 	"fmt"
+	"net"
 	"strings"
 	"time"
 )
@@ -85,20 +86,31 @@ func (p *ServerProfile) BuildServerURL(ip ...string) string {
 	return fmt.Sprintf("%s://%s:%d%s", protocol, host, port, path)
 }
 
-// GetServerIPList parses ServerIPs into a string slice.
-func (p *ServerProfile) GetServerIPList() []string {
+// ValidateServerIPs parses ServerIPs, returning valid IP addresses
+// and any invalid entries (for UI error reporting).
+func (p *ServerProfile) ValidateServerIPs() (valid []string, invalid []string) {
 	if p.ServerIPs == "" {
-		return nil
+		return nil, nil
 	}
-	parts := strings.Split(p.ServerIPs, ",")
-	var out []string
-	for _, part := range parts {
+	for _, part := range strings.Split(p.ServerIPs, ",") {
 		s := strings.TrimSpace(part)
-		if s != "" {
-			out = append(out, s)
+		if s == "" {
+			continue
+		}
+		if net.ParseIP(s) != nil {
+			valid = append(valid, s)
+		} else {
+			invalid = append(invalid, s)
 		}
 	}
-	return out
+	return
+}
+
+// GetServerIPList returns only valid IP addresses from ServerIPs,
+// silently filtering out any malformed entries.
+func (p *ServerProfile) GetServerIPList() []string {
+	valid, _ := p.ValidateServerIPs()
+	return valid
 }
 
 // ConnectionStatus records the outcome of a connection attempt.

internal/ui/profile.go

@@ -3,6 +3,7 @@ package ui
 import (
 	"fmt"
 	"strconv"
+	"strings"
 
 	"lmvpn/internal/i18n"
 	"lmvpn/internal/model"
@@ -270,6 +271,17 @@ func (a *App) saveProfile(editing *model.ServerProfile,
 		return false
 	}
 
+	if ips != "" {
+		tmp := &model.ServerProfile{ServerIPs: ips}
+		_, invalid := tmp.ValidateServerIPs()
+		if len(invalid) > 0 {
+			showError(i18n.T("DlgValidationTitle"),
+				fmt.Sprintf(i18n.T("DlgInvalidIPMsg"), strings.Join(invalid, ", ")),
+				a.window)
+			return false
+		}
+	}
+
 	port := parseIntDefault(portStr, 443)
 	mtu := parseIntDefault(mtuStr, 0)
 

internal/vpn/session.go

@@ -185,33 +185,45 @@ func (sm *SessionManager) run(ctx context.Context, cfg SessionConfig) {
 		if err != nil {
 			log.L().Error("VPN connection failed", "error", err)
 
-			// A TLS certificate verification failure is not retryable:
-			// the cert won't change between attempts, so stop the
-			// loop and surface the reason to the user.
+			// A TLS certificate verification failure on the original
+			// hostname (ipIndex == 0) is not retryable: the cert won't
+			// change between attempts, so stop the loop and surface the
+			// reason to the user. On a CDN edge IP (ipIndex > 0) the
+			// TLS error likely means that IP points to a different
+			// server; skip it and try the next target.
 			if tlsconfig.IsTLSError(err) {
-				log.L().Warn("fatal TLS error, stopping reconnect", "error", err)
-				sm.setState(stats.StateError)
-				if sm.onError != nil {
-					sm.onError("tls_error", err.Error())
+				if ipIndex == 0 {
+					log.L().Warn("fatal TLS error, stopping reconnect", "error", err)
+					sm.setState(stats.StateError)
+					if sm.onError != nil {
+						sm.onError("tls_error", err.Error())
+					}
+					fatal = true
+					sm.cleanup()
+					return
 				}
-				fatal = true
-				sm.cleanup()
-				return
+				log.L().Warn("TLS error on CDN IP, skipping",
+					"index", ipIndex, "ip", targets[ipIndex], "error", err)
 			}
 
 			// A fatal authentication failure (wrong password, disabled
-			// account, expired token, rate limit) is not retryable:
-			// stop the loop and surface the reason to the user instead
-			// of hammering the server forever.
+			// account, expired token, rate limit) on the original
+			// hostname is not retryable. On a CDN edge IP it likely
+			// means the IP points to a different server that returned
+			// 401/403, so skip it instead of stopping the loop.
 			if code, msg, isFatal := fatalAuthError(err); isFatal {
-				log.L().Warn("fatal auth error, stopping reconnect", "code", code, "message", msg)
-				sm.setState(stats.StateError)
-				if sm.onError != nil {
-					sm.onError(string(code), msg)
+				if ipIndex == 0 {
+					log.L().Warn("fatal auth error, stopping reconnect", "code", code, "message", msg)
+					sm.setState(stats.StateError)
+					if sm.onError != nil {
+						sm.onError(string(code), msg)
+					}
+					fatal = true
+					sm.cleanup()
+					return
 				}
-				fatal = true
-				sm.cleanup()
-				return
+				log.L().Warn("auth error on CDN IP, skipping",
+					"index", ipIndex, "ip", targets[ipIndex], "code", code)
 			}
 
 			sm.setState(stats.StateReconnecting)
@@ -673,7 +685,14 @@ func wsURLToHTTP(wsURL string) (string, error) {
 
 // replaceHost substitutes the host portion of a URL string.
 // e.g. wss://host:443/ws with 1.2.3.4 → wss://1.2.3.4:443/ws
+// Bare IPv6 addresses are automatically bracketed:
+// wss://host:443/ws with 2001:db8::1 → wss://[2001:db8::1]:443/ws
 func replaceHost(rawURL, newHost string) string {
+	// Auto-bracket bare IPv6 addresses so the colons in the address
+	// are not confused with the port separator.
+	if ip := net.ParseIP(newHost); ip != nil && ip.To4() == nil && !strings.HasPrefix(newHost, "[") {
+		newHost = "[" + newHost + "]"
+	}
 	u := rawURL
 	for _, prefix := range []string{"wss://", "ws://"} {
 		if len(u) > len(prefix) && u[:len(prefix)] == prefix {