How to use URLSession with Proxy in Swift 3

Question

For an API Request I'm trying to setup an URLSession using a Proxy. For test purposes I'm using a public Proxy and an API responding the IP.

func makeRequestViaUrlSessionProxy(_ url: String, completion: @escaping (_ result: String?) -> ()) {

    let request = URLRequest(url: URL(string: url)!)

    let config = URLSessionConfiguration.default
    config.requestCachePolicy = URLRequest.CachePolicy.reloadIgnoringLocalCacheData
    config.connectionProxyDictionary = [AnyHashable: Any]()
    config.connectionProxyDictionary?[kCFNetworkProxiesHTTPEnable as String] = 1
    config.connectionProxyDictionary?[kCFNetworkProxiesHTTPProxy as String] = "142.54.173.19"
    config.connectionProxyDictionary?[kCFNetworkProxiesHTTPPort as String] = 8888

    let session = URLSession.init(configuration: config, delegate: nil, delegateQueue: OperationQueue.current)

    let task = session.dataTask(with: request) {
        (data: Data?, response: URLResponse?, error: Error?) in
        if error != nil {
            NSLog("Client-side error in request to \(url): \(error)")
            completion(nil)
            return
        }

        if data == nil {
            NSLog("Data from request to \(url) is nil")
            completion(nil)
            return
        }

        let httpResponse = response as? HTTPURLResponse
        if httpResponse?.statusCode != 200 {
            NSLog("Server-side error in request to \(url): \(httpResponse)")
            completion(nil)
            return
        }

        let encodingName = response?.textEncodingName != nil ? response?.textEncodingName : "utf-8"
        let encoding = CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding(encodingName as CFString!))
        let stringData = String(data: data!, encoding: String.Encoding(rawValue: UInt(encoding)))
        session.invalidateAndCancel()
        completion(stringData)
    }
    task.resume()
}

Called by:

override func viewDidLoad() {
    super.viewDidLoad()
    makeRequestViaUrlSessionProxy("https://api.ipify.org?format=json") { string in
        print(string)
    }
}

It seems like the config is completely ignored because even with made up Proxy IP, the responded IP is always the actual devices IP

Any help is highly appreciated.

Edit: as suggested by User hasan83, taking "the HTTPS keys" seems not an option.

Answer 1

I think the working (supposed to be deprecated) keys are:

kCFStreamPropertyHTTPSProxyHost
kCFStreamPropertyHTTPSProxyPort

Could you try this code?

func makeRequestViaUrlSessionProxy(_ url: String, completion: @escaping (_ result: String?) -> ()) {

    let request = URLRequest(url: URL(string: url)!)

    let config = URLSessionConfiguration.default
    config.requestCachePolicy = URLRequest.CachePolicy.reloadIgnoringLocalCacheData
    config.connectionProxyDictionary = [AnyHashable: Any]()
    config.connectionProxyDictionary?[kCFNetworkProxiesHTTPEnable as String] = 1
    config.connectionProxyDictionary?[kCFNetworkProxiesHTTPProxy as String] = "142.54.173.19"
    config.connectionProxyDictionary?[kCFNetworkProxiesHTTPPort as String] = 8888
    config.connectionProxyDictionary?[kCFStreamPropertyHTTPSProxyHost as String] = "142.54.173.19"
    config.connectionProxyDictionary?[kCFStreamPropertyHTTPSProxyPort as String] = 8888

    let session = URLSession.init(configuration: config, delegate: nil, delegateQueue: OperationQueue.current)

    let task = session.dataTask(with: request) {
        (data: Data?, response: URLResponse?, error: Error?) in
        if error != nil {
            NSLog("Client-side error in request to \(url): \(error)")
            completion(nil)
            return
        }

        if data == nil {
            NSLog("Data from request to \(url) is nil")
            completion(nil)
            return
        }

        let httpResponse = response as? HTTPURLResponse
        if httpResponse?.statusCode != 200 {
            NSLog("Server-side error in request to \(url): \(httpResponse)")
            completion(nil)
            return
        }

        let encodingName = response?.textEncodingName != nil ? response?.textEncodingName : "utf-8"
        let encoding = CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding(encodingName as CFString!))
        let stringData = String(data: data!, encoding: String.Encoding(rawValue: UInt(encoding)))
        session.invalidateAndCancel()
        completion(stringData)
    }
    task.resume()
}

Also please make sure your proxy server is configured to handle https requests.

Note: It might give deprecated warning for those keys but keys are still working (see https://forums.developer.apple.com/thread/19356#131446)

Answer 2

I am not sure if that make sense. But, there is two defferent set of keys here:

1. HTTP
2. HTTPS

Proxy Keys:

// http proxy keys
kCFNetworkProxiesHTTPEnable
kCFNetworkProxiesHTTPProxy
kCFNetworkProxiesHTTPPort

// https proxy keys
kCFNetworkProxiesHTTPSEnable
kCFNetworkProxiesHTTPSProxy
kCFNetworkProxiesHTTPSPort