A class to facilitate publishing a Bonjour service in Swift

BonjourPublisher.swift

//
//  BonjourPublisher.swift
//  BonjourTest
//
//  Created by Dov Frankel on 10/12/15.
//  Copyright © 2015 Dov Frankel. All rights reserved.
//

import Foundation

public enum BonjourServerError: ErrorType {
    case SettingIPv6Options
    case BindingIPv4
    case BindingIPv6
    case GettingSocketIPv4
    case GettingSocketIPv6
    case ListeningIPv4
    case ListeningIPv6
    case CreatingNativeSocket
    case CreatingSocketRunLoopSource
    case PublishingService([String : NSNumber])
}

@objc
public class BonjourPublisher: NSObject, NSNetServiceDelegate {

    public let serviceType: String
    public let serviceName: String
    
    private var service: NSNetService!
    private var serviceSocket: CFSocket!
    private var serviceRunLoopSource: CFRunLoopSource!
    
    private var publishCompletedCallback: ((success: Bool, error: BonjourServerError?) -> Void)!
    
    init(serviceType: String, serviceName: String) {
        self.serviceType = serviceType
        self.serviceName = serviceName
    }
    
    convenience init(serviceType: String) {
        self.init(serviceType: serviceType, serviceName: "")
    }
    
    public func configure(completionBlock: (success: Bool, error: BonjourServerError?) -> Void) {
        dispatch_async(dispatch_get_main_queue()) {
            let fd4, fd6: Int32
            let port: in_port_t
            
            do {
                (fd4, port) = try self.registerIPv4Socket()
                fd6 = try self.registerIPv6Socket(port)
            } catch let socketError {
                NSLog("Failed to register a socket: BonjourServerError.\(socketError)")
                completionBlock(success: false, error: socketError as? BonjourServerError)
                return
            }
            
            do {
                try self.hookUpSocket(fd4)
            } catch let socketError {
                NSLog("Failed to hoook up an IPv4 socket: BonjourServerError.\(socketError)")
                completionBlock(success: false, error: socketError as? BonjourServerError)
                return
            }
            
            do {
                try self.hookUpSocket(fd6)
            } catch let socketError {
                NSLog("Failed to hoook up an IPv6 socket: BonjourServerError.\(socketError)")
                completionBlock(success: false, error: socketError as? BonjourServerError)
                return
            }
            
            self.publishCompletedCallback = completionBlock
            
            self.service = self.publishService(port)
        }
    }
    
    private func registerIPv4Socket() throws -> (Int32, in_port_t) {
        let fd4 = socket(AF_INET, SOCK_STREAM, 0)
        
        var sin = sockaddr_in()
        sin.sin_family = sa_family_t(AF_INET)
        sin.sin_len = UInt8(sizeofValue(sin))
        sin.sin_port = 0
        
        let bindError = withUnsafePointer(&sin) {
            Foundation.bind(fd4, UnsafePointer($0), UInt32(sin.sin_len))
        }
        
        guard bindError == 0 else {
            throw BonjourServerError.BindingIPv4
        }
        
        var addrLen = socklen_t(sizeofValue(sin))
        
        let socketError = withUnsafeMutablePointers(&sin, &addrLen) { (sinPtr, addrPtr) -> Int32 in
            getsockname(fd4, UnsafeMutablePointer(sinPtr), UnsafeMutablePointer(addrPtr))
        }
        
        guard socketError == 0 else {
            throw BonjourServerError.GettingSocketIPv4
        }
        
        let listenError = listen(fd4, 5)
        
        guard listenError == 0 else {
            throw BonjourServerError.ListeningIPv4
        }
        
        return (fd4, sin.sin_port)
    }
    
    private func registerIPv6Socket(port: in_port_t) throws -> Int32 {
        let fd6 = socket(AF_INET6, SOCK_STREAM, 0)
        
        var one: Int32 = 1
        let sockOptError = withUnsafePointer(&one) {
            setsockopt(fd6, IPPROTO_IPV6, IPV6_V6ONLY, UnsafePointer($0), socklen_t(sizeofValue(one)))
        }
        
        guard sockOptError == 0 else {
            throw BonjourServerError.SettingIPv6Options
        }
        
        var sin6 = sockaddr_in6()
        sin6.sin6_family = sa_family_t(AF_INET6)
        sin6.sin6_len = UInt8(sizeofValue(sin6))
        sin6.sin6_port = port.bigEndian
        
        let bindError = withUnsafePointer(&sin6) {
            Foundation.bind(fd6, UnsafePointer($0), UInt32(sin6.sin6_len))
        }
        
        guard bindError == 0 else {
            throw BonjourServerError.BindingIPv6
        }
        
        var addrLen = socklen_t(sizeofValue(sin6))
        
        let socketError = withUnsafeMutablePointers(&sin6, &addrLen) { (sinPtr, addrPtr) -> Int32 in
            getsockname(fd6, UnsafeMutablePointer(sinPtr), UnsafeMutablePointer(addrPtr))
        }
        
        guard socketError == 0 else {
            throw BonjourServerError.GettingSocketIPv6
        }
        
        let listenError = listen(fd6, 5)
        
        guard listenError == 0 else {
            throw BonjourServerError.ListeningIPv6
        }
        
        return fd6
    }
    
    private func hookUpSocket(fd: CFSocketNativeHandle) throws {
        var context = CFSocketContext()
        
        var selfPtr = self
        withUnsafeMutablePointer(&selfPtr) {
            context.info = UnsafeMutablePointer<Void>($0)
        }
        
        serviceSocket = withUnsafePointer(&context) {
            CFSocketCreateWithNative(nil, fd, CFSocketCallBackType.AcceptCallBack.rawValue, CallbackListen, UnsafePointer<CFSocketContext>($0))
        }
        
        guard serviceSocket != nil && CFSocketIsValid(serviceSocket) else {
            throw BonjourServerError.CreatingNativeSocket
        }
        
        serviceRunLoopSource = CFSocketCreateRunLoopSource(nil, serviceSocket, 0)
        
        guard serviceRunLoopSource != nil && CFRunLoopSourceIsValid(serviceRunLoopSource) else {
            throw BonjourServerError.CreatingSocketRunLoopSource
        }
        
        CFRunLoopAddSource(CFRunLoopGetCurrent(), serviceRunLoopSource, kCFRunLoopCommonModes)
    }
    
    private func publishService(port: in_port_t) -> NSNetService {
        let serviceTypeAndTransport = "_\(self.serviceType)._tcp."
        let service = NSNetService(domain: "", type: serviceTypeAndTransport, name: serviceName, port: Int32(port.bigEndian))
        
        service.delegate = self
        service.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSRunLoopCommonModes)
        service.publish()
        
        return service
    }
    
    
    // MARK: - Callbacks
    
    
    @objc public func netServiceDidPublish(sender: NSNetService) {
        NSLog("Advertising service with name '\(sender.name)' on port \(sender.port)")
        guard publishCompletedCallback != nil else {
            NSLog("Publish succeeded, but there was no callback reference")
            return
        }
        
        publishCompletedCallback(success: true, error: nil)
        self.publishCompletedCallback = nil
    }
    
    @objc public func netService(sender: NSNetService, didNotPublish errorDict: [String : NSNumber]) {
        NSLog("Error publishing: \(errorDict)")
        guard publishCompletedCallback != nil else {
            NSLog("Publish failed, but there was no callback reference")
            return
        }
        
        publishCompletedCallback(success: false, error: BonjourServerError.PublishingService(errorDict))
        self.publishCompletedCallback = nil
    }
}

func CallbackListen(s: CFSocket!, callbackType: CFSocketCallBackType, address: CFData!, data: UnsafePointer<Void>, info: UnsafeMutablePointer<Void>) {
    NSLog("Callback called")
}

Updated to fix bug in Stack Overflow question.

how can I make this work for peer to peer connections? seems this doesn't like ipv6.