Question

我想从Swift的DNS查询中获取IP服装（如192.168.0.1或87.12.56.50）。我用100种不同的方法尝试了100次......没有什么帮助我，所以我不得不寻求帮助（我希望这里有很多人;））到目前为止，这是我的代码：

let host = CFHostCreateWithName(nil,"subdomain.of.stackoverflow.com").takeUnretainedValue();
CFHostStartInfoResolution(host, .Addresses, nil);
var success: Boolean = 0;
let addresses = CFHostGetAddressing(host, &success).takeUnretainedValue() as NSArray;
if(addresses.count > 0){
   let theAddress = addresses[0] as NSData;
   println(theAddress);
}

好的......这些是我试图实现但未成功实现的代码的链接： https://gist.github.com/mikeash/bca3a341db74221625f5
How to perform DNS query on iOS
Create an Array in Swift from an NSData Object
Does CFHostGetAddressing() support ipv6 DNS entries?
Do a simple DNS lookup in Swift
因此，如果我们对此问题进行无意义的否定投票，我们可以尝试找到解决方案并帮助其他人（像我一样）

Answer 1

您的代码将地址检索为＆＃34;套接字地址＆＃34;结构体。 getnameinfo()可用于将地址转换为数字IP字符串（从https://stackoverflow.com/a/25627545/1187415回收的代码，现已更新为 Swift 2 ）：

let host = CFHostCreateWithName(nil,"www.google.com").takeRetainedValue()
CFHostStartInfoResolution(host, .Addresses, nil)
var success: DarwinBoolean = false
if let addresses = CFHostGetAddressing(host, &success)?.takeUnretainedValue() as NSArray?,
    let theAddress = addresses.firstObject as? NSData {
    var hostname = [CChar](count: Int(NI_MAXHOST), repeatedValue: 0)
    if getnameinfo(UnsafePointer(theAddress.bytes), socklen_t(theAddress.length),
        &hostname, socklen_t(hostname.count), nil, 0, NI_NUMERICHOST) == 0 {
            if let numAddress = String.fromCString(hostname) {
                print(numAddress)
            }
    }
}

输出（示例）：173.194.112.147

还要注意第一行中takeRetainedValue()的用法，因为 CFHostCreateWithName()已经＆＃34;创建＆＃34;因此，在其名称中返回保留的（+1）对象

更新Swift 3 / Xcode 8：

let host = CFHostCreateWithName(nil,"www.google.com" as CFString).takeRetainedValue()
CFHostStartInfoResolution(host, .addresses, nil)
var success: DarwinBoolean = false
if let addresses = CFHostGetAddressing(host, &success)?.takeUnretainedValue() as NSArray?,
    let theAddress = addresses.firstObject as? NSData {
    var hostname = [CChar](repeating: 0, count: Int(NI_MAXHOST))
    if getnameinfo(theAddress.bytes.assumingMemoryBound(to: sockaddr.self), socklen_t(theAddress.length),
                   &hostname, socklen_t(hostname.count), nil, 0, NI_NUMERICHOST) == 0 {
        let numAddress = String(cString: hostname)
        print(numAddress)
    }
}

或者，为主机获取所有 IP地址：

let host = CFHostCreateWithName(nil,"www.google.com" as CFString).takeRetainedValue()
CFHostStartInfoResolution(host, .addresses, nil)
var success: DarwinBoolean = false
if let addresses = CFHostGetAddressing(host, &success)?.takeUnretainedValue() as NSArray? {
    for case let theAddress as NSData in addresses {
        var hostname = [CChar](repeating: 0, count: Int(NI_MAXHOST))
        if getnameinfo(theAddress.bytes.assumingMemoryBound(to: sockaddr.self), socklen_t(theAddress.length),
                       &hostname, socklen_t(hostname.count), nil, 0, NI_NUMERICHOST) == 0 {
            let numAddress = String(cString: hostname)
            print(numAddress)
        }
    }
}

Answer 2

请参阅以下Swift代码以获取网站的DNS解析。一种方法使用CFHostStartInfoResolution，而另一种方法使用gethostbyname。

这两个API均支持全部/多个IP地址解析。

private func urlToIP_cfHostResolution(_ url: String) -> [String] {

    var ipList: [String] = []

    let host = CFHostCreateWithName(nil,url as CFString).takeRetainedValue()

    CFHostStartInfoResolution(host, .addresses, nil)

    var success: DarwinBoolean = false

    if let addresses = CFHostGetAddressing(host, &success)?.takeUnretainedValue() as NSArray? {

        for case let theAddress as NSData in addresses {

            var hostname = [CChar](repeating: 0, count: Int(NI_MAXHOST))

            if getnameinfo(theAddress.bytes.assumingMemoryBound(to: sockaddr.self), socklen_t(theAddress.length),
                       &hostname, socklen_t(hostname.count), nil, 0, NI_NUMERICHOST) == 0 {

                ipList.append(String(cString: hostname))
            }    
        }
    }

    return ipList
}

此方法为["151.101.129.69", "151.101.1.69", "151.101.193.69", "151.101.65.69"]返回www.stackoverflow.com

private func urlToIP_gethostbyname(_ url: URL) -> [String] {

    var ipList: [String] = []

    guard let hostname = url.host else {

        return ipList
    }

    guard let host = hostname.withCString({gethostbyname($0)}) else {

        return ipList
    }

    guard host.pointee.h_length > 0 else {

        return ipList
    }

    var index = 0

    while host.pointee.h_addr_list[index] != nil {

        var addr: in_addr = in_addr()

        memcpy(&addr.s_addr, host.pointee.h_addr_list[index], Int(host.pointee.h_length))

        guard let remoteIPAsC = inet_ntoa(addr) else {

            return ipList
        }

        ipList.append(String.init(cString: remoteIPAsC))

        index += 1
    }

    return ipList
}

此方法还会为["151.101.129.69", "151.101.1.69", "151.101.193.69", "151.101.65.69"]返回www.stackoverflow.com

希望这会有所帮助。

Answer 3

许多答案正在使用不赞成使用的bytes来检索sockaddr，以提供给getnameinfo。我们现在将使用address.withUnsafeBytes。例如，在Swift 5中：

/// Returns the string representation of the supplied address.
///
/// - parameter address: Contains a `(struct sockaddr)` with the address to render.
///
/// - returns: A string representation of that address.

func stringRepresentation(forAddress address: Data) -> String? {
    address.withUnsafeBytes { pointer in
        var hostStr = [Int8](repeating: 0, count: Int(NI_MAXHOST))

        let result = getnameinfo(
            pointer.baseAddress?.assumingMemoryBound(to: sockaddr.self),
            socklen_t(address.count),
            &hostStr,
            socklen_t(hostStr.count),
            nil,
            0,
            NI_NUMERICHOST
        )
        guard result == 0 else { return nil }
        return String(cString: hostStr)
    }
}

如何从Swift的DNS查询中获取真实的IP地址？

3 个答案: