数据包隧道提供程序IOS中的动态DNS

问题描述

我使用分组隧道提供程序让应用包含vpn配置 在tunnelNetworkSettings.dnsSettings上设置隧道时，我们将8.8.8.8 可以通过设备使用的dns（例如wifi，4g等）将其更改为动态的任何优雅且合法的方法

让dnsSettings = NednSSettings（服务器：[8.8.8.8]）

tunnelNetworkSettings.dnsSettings = dnsSettings

解决方法

您可以使用此代码获取系统 DNS 服务器

static func getSystemDnsList() -> ([String]/*IPV4*/,[String]/*IPV6*/) {
        var dnsListIPV4 = [String]()
        var dnsListIPV6 = [String]()
            let structSize = MemoryLayout<__res_9_state>.size
            let res = UnsafeMutablePointer<__res_9_state>.allocate(capacity: structSize)
            let result = res_9_ninit(res)
            if result == 0 {
                let structSize = MemoryLayout<res_9_sockaddr_union>.size
                let capacity = Int(res.pointee.nscount) * structSize

                let addrUnion = UnsafeMutablePointer<res_9_sockaddr_union>.allocate(capacity: capacity)
                res_9_getservers(res,addrUnion,res.pointee.nscount)

                for i in 0..<Int(res.pointee.nscount) {
                    if addrUnion[i].sin.sin_family == AF_INET {
                        let ip = UnsafeMutablePointer<Int8>.allocate(capacity: Int(INET_ADDRSTRLEN))

                        var ipStringObject : String?
                        if let ipStr = inet_ntop(AF_INET,&(addrUnion[i].sin.sin_addr),ip,socklen_t(INET_ADDRSTRLEN)) {
                            ipStringObject = String(utf8String: ipStr)
                        }

                        var portStringObject : String?
                        let port = nTohs(addrUnion[i].sin.sin_port)
                        portStringObject = String(format: "%d",port)

                        if let ip = ipStringObject {
                            dnsListIPV4.append(ip)
                        }
                    } else if addrUnion[i].sin6.sin6_family == AF_INET6 {
                        let ip = UnsafeMutablePointer<Int8>.allocate(capacity: Int(INET6_ADDRSTRLEN))

                        var ipStringObject : String?
                        if let ipStr = inet_ntop(AF_INET6,&(addrUnion[i].sin6.sin6_addr),socklen_t(INET6_ADDRSTRLEN)) {
                            ipStringObject = String(utf8String: ipStr)
                        }

                        var portStringObject : String?
                        let port = nTohs(addrUnion[i].sin6.sin6_port)
                        portStringObject = String(format: "%d",port)

                        if let ip = ipStringObject {
                            dnsListIPV6.append(ip)
                        }
                    }
                }

                res_9_nclose(res)
                free(res)
            }

            return (dnsListIPV4,dnsListIPV6)
        }