Estou tentando usarTransporte seguro com soquetes BSD usando Swift. Parece que deve ser bastante simples, mas não consigo fazê-lo funcionar e a documentação sobre o assunto é escassa.

Eu reduzi meu problema a uma classe simples "Socket", na qual (dentro do meu conhecimento) atendi aos requisitos do Transporte Seguro.

import Cocoa

class Socket: NSObject {

    private let hello = "Hello!"
    private var socketfd: Int32
    private var sock_addr: sockaddr

    private var sslContext: SSLContext?

    var sslWriteCallbackFunc: SSLWriteFunc {
        get {
            let ump = UnsafeMutablePointer<((SSLConnectionRef, UnsafePointer<Void>,
                UnsafeMutablePointer<Int>) -> OSStatus)>.alloc(1)

            ump.initialize(sslWriteCallback)

            return CFunctionPointer<((SSLConnectionRef, UnsafePointer<Void>,
                UnsafeMutablePointer<Int>) -> OSStatus)>(COpaquePointer(ump))
        }
    }

    var sslReadCallbackFunc: SSLReadFunc {
        get {
            let ump = UnsafeMutablePointer<((SSLConnectionRef, UnsafeMutablePointer<Void>,
                UnsafeMutablePointer<Int>) -> OSStatus)>.alloc(1)

            ump.initialize(sslReadCallback)

            return CFunctionPointer<((SSLConnectionRef, UnsafeMutablePointer<Void>,
                UnsafeMutablePointer<Int>) -> OSStatus)>(COpaquePointer(ump))
        }
    }

    init(address: String, port: UInt16) {
        socketfd = Darwin.socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)

        var addr = Darwin.sockaddr_in(sin_len: __uint8_t(sizeof(sockaddr_in)), sin_family: sa_family_t(AF_INET), sin_port: CFSwapInt16(port), sin_addr: in_addr(s_addr: inet_addr(address)), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        sock_addr = Darwin.sockaddr(sa_len: 0, sa_family: 0, sa_data: (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0))
        Darwin.memcpy(&sock_addr, &addr, Int(sizeof(sockaddr_in)))

        super.init()
    }

    func connect() -> Socket {
        let err = Darwin.connect(socketfd, &sock_addr, socklen_t(sizeof(sockaddr_in)))

        return self
    }

    func makeSecure() -> Socket {
        if let umc = SSLCreateContext(nil, kSSLClientSide, kSSLStreamType) {
            sslContext = umc.takeRetainedValue()

            var status = SSLSetIOFuncs(sslContext!, sslReadCallbackFunc, sslWriteCallbackFunc)
            status = SSLSetConnection(sslContext!, &socketfd)

            SSLHandshake(sslContext!)
        }

        return self
    }

    func sendHello() -> Socket {
        let bytes = [UInt8](hello.utf8)
        let data = NSData(bytes: bytes, length: bytes.count)

        let test = UnsafeMutablePointer<Int>.alloc(1)
        test.initialize(bytes.count)

        self.sslWriteCallback(&socketfd, data: data.bytes, dataLength: test)

        return self
    }

    // MARK: - SSL Callback Methods

    func sslReadCallback(connection: SSLConnectionRef,
        data: UnsafeMutablePointer<Void>,
        dataLength: UnsafeMutablePointer<Int>) -> OSStatus {

            let bytesRead = read(socketfd, data, UnsafePointer<Int>(dataLength).memory)

            return noErr
    }

    func sslWriteCallback(connection: SSLConnectionRef,
        data: UnsafePointer<Void>,
        dataLength: UnsafeMutablePointer<Int>) -> OSStatus {

            let sent = Darwin.sendto(socketfd, data, UnsafePointer<Int>(dataLength).memory, 0, &sock_addr, socklen_t(sizeof(sockaddr_in)))
            if (sent < 0) {
                let error = NSError(domain: NSPOSIXErrorDomain, code: Int(errno), userInfo: nil)
                println(error.localizedDescription)
            } else {
                println("Sent \(sent) bytes (\(hello))")
            }

            return noErr
    }
}

Testei a comunicação de soquete não TLS criando uma instância simples:

let socket = Socket(address: "some-ip-address", port: 8080)
socket.connect().sendHello()

e executando um servidor de eco na máquina de destino usando o netcat. Isso funciona bem.

nc -l -p 8080

A tentativa de quebrar o soquete no TLS do Secure Transport (chamando o método makeSecure ()) trava na chamada para SSLHandshake (...) com um erro EXC_BAD_ADDRESS (código = 2, endereço = ...). Alguém tem alguma indicação do que estou perdendo aqui?

EDITAR

Vejo o console publicar:

04/06/15 09:20:48,000 kernel[0]: Data/Stack execution not permitted: TheProject[pid 29184] at virtual address 0x100602000, protections were read-write

EDIT 2

Consegui trabalhar com o Swift 2 no Xcode 7 beta. Ver abaixo.