How to get Ip address in swift

Question

How do i get my local IpAddress?

I tried to use this Obj C example: how to get ip address of iphone programmatically

When i get to the function getifaddrs() i can't get any further. i can't use the function.

Is there an alternative way to do this, or am I approaching this the wrong way?

Answer 1

Code works for Swift 5+ and iOS 13+

To get IPAddress of device on turning Wifi or Wired or Mobile data ON, use below method :

func getIPAddress() -> String? {
    var address : String?

    // Get list of all interfaces on the local machine:
    var ifaddr : UnsafeMutablePointer<ifaddrs>?
    guard getifaddrs(&ifaddr) == 0 else { return nil }
    guard let firstAddr = ifaddr else { return nil }

    // For each interface ...
    for ifptr in sequence(first: firstAddr, next: { $0.pointee.ifa_next }) {
        let interface = ifptr.pointee

        // Check for IPv4 or IPv6 interface:
        let addrFamily = interface.ifa_addr.pointee.sa_family
        if addrFamily == UInt8(AF_INET) || addrFamily == UInt8(AF_INET6) {

            // Check interface name:
            // wifi = ["en0"]
            // wired = ["en2", "en3", "en4"]
            // cellular = ["pdp_ip0","pdp_ip1","pdp_ip2","pdp_ip3"]
            
            let name = String(cString: interface.ifa_name)
            if  name == "en0" || name == "en2" || name == "en3" || name == "en4" || name == "pdp_ip0" || name == "pdp_ip1" || name == "pdp_ip2" || name == "pdp_ip3" {

                // Convert interface address to a human readable string:
                var hostname = [CChar](repeating: 0, count: Int(NI_MAXHOST))
                getnameinfo(interface.ifa_addr, socklen_t(interface.ifa_addr.pointee.sa_len),
                            &hostname, socklen_t(hostname.count),
                            nil, socklen_t(0), NI_NUMERICHOST)
                address = String(cString: hostname)
            }
        }
    }
    freeifaddrs(ifaddr)

    return address
}

Here, code/checks works for Wifi, Wired and Mobile data is:

if name == "en0" || name == "en2" || name == "en3" || name == "en4" || name == "pdp_ip0" || name == "pdp_ip1" || name == "pdp_ip2" || name == "pdp_ip3"

Hope will be helping! :)

Answer 2

In Swift 5 you can use ioctl directly with Swift rather than resorting to 'C' to get the IP address details for a given interface.

Like this:

private enum AddressRequestType {
    case ipAddress
    case netmask
}

// From BDS ioccom.h
// Macro to create ioctl request
private static func _IOC (_ io: UInt32, _ group: UInt32, _ num: UInt32, _ len: UInt32) -> UInt32 {
    let rv = io | (( len & UInt32(IOCPARM_MASK)) << 16) | ((group << 8) | num)
    return rv
}

// Macro to create read/write IOrequest
private static func _IOWR (_ group: Character , _ num : UInt32, _ size: UInt32) -> UInt32 {
    return _IOC(IOC_INOUT, UInt32 (group.asciiValue!), num, size)
}

private static func _interfaceAddressForName (_ name: String, _ requestType: AddressRequestType) throws -> String {
    
    var ifr = ifreq ()
    ifr.ifr_ifru.ifru_addr.sa_family = sa_family_t(AF_INET)
    
    // Copy the name into a zero padded 16 CChar buffer
    
    let ifNameSize = Int (IFNAMSIZ)
    var b = [CChar] (repeating: 0, count: ifNameSize)
    strncpy (&b, name, ifNameSize)
    
    // Convert the buffer to a 16 CChar tuple - that's what ifreq needs
    ifr.ifr_name = (b [0], b [1], b [2], b [3], b [4], b [5], b [6], b [7], b [8], b [9], b [10], b [11], b [12], b [13], b [14], b [15])
    
    let ioRequest: UInt32 = {
        switch requestType {
        case .ipAddress: return _IOWR("i", 33, UInt32(MemoryLayout<ifreq>.size))    // Magic number SIOCGIFADDR - see sockio.h
        case .netmask: return _IOWR("i", 37, UInt32(MemoryLayout<ifreq>.size))      // Magic number SIOCGIFNETMASK
        }
    } ()
    
    if ioctl(socket(AF_INET, SOCK_DGRAM, 0), UInt(ioRequest), &ifr) < 0 {
        throw POSIXError (POSIXErrorCode (rawValue: errno) ?? POSIXErrorCode.EINVAL)
    }
    
    let sin = unsafeBitCast(ifr.ifr_ifru.ifru_addr, to: sockaddr_in.self)
    let rv = String (cString: inet_ntoa (sin.sin_addr))
    
    return rv
}

public static func getInterfaceIPAddress (interfaceName: String) throws -> String {
    return try _interfaceAddressForName(interfaceName, .ipAddress)
}

public static func getInterfaceNetMask (interfaceName: String) throws -> String {
    return try _interfaceAddressForName(interfaceName, .netmask)
}

Answer 3

   func getIfConfigOutput() -> [String:String] {
    let cmd = "for i in $(ifconfig -lu); do if ifconfig $i | grep -q \"status: active\" ; then echo $i; fi; done"
    let interfaceString = shell(cmd)
    let interfaceArray = interfaceString.components(separatedBy: "\n")
    var finalDictionary:[String:String] = [String:String]()
    for (i,_) in interfaceArray.enumerated() {
        if (interfaceArray[i].hasPrefix("en")){
            let sp = shell("ifconfig \(interfaceArray[i]) | grep \"inet \" | grep -v 127.0.0.1 | cut -d\\  -f2")
          finalDictionary[interfaceArray[i]] = sp.replacingOccurrences(of: "\n", with: "")
        }
    }
  print(finalDictionary)
    return finalDictionary
}
func shell(_ args: String) -> String {
    var outstr = ""
    let task = Process()
    task.launchPath = "/bin/sh"
    task.arguments = ["-c", args]
    let pipe = Pipe()
    task.standardOutput = pipe
    task.launch()
    let data = pipe.fileHandleForReading.readDataToEndOfFile()
    if let output = NSString(data: data, encoding: String.Encoding.utf8.rawValue) {
        outstr = output as String
    }
    task.waitUntilExit()
    return outstr
}

This will help you. Code Returns a Dictionary with Interfaces and IP Addresses Associated with it.

Answer 4

As it turned out in the discussion, OP needs the interface address on a Mac and not on an iOS device as I thought initially. The code referenced in the question checks for the interface name "en0", which is the WiFi interface on the iPhone. On a Mac it makes more sense to check for any "up-and-running" interface instead. Therefore I have rewritten the answer. It is now a Swift translation of the code in Detect any connected network.

---

getifaddrs() is defined in <ifaddrs.h>, which is not included by default. Therefore you have to create a bridging header and add

#include <ifaddrs.h>

The following function returns an array with the names of all local "up-and-running" network interfaces.

func getIFAddresses() -> [String] {
    var addresses = [String]()

    // Get list of all interfaces on the local machine:
    var ifaddr : UnsafeMutablePointer<ifaddrs> = nil
    if getifaddrs(&ifaddr) == 0 {

        // For each interface ...
        var ptr = ifaddr
        while ptr != nil {
            defer { ptr = ptr.memory.ifa_next } 

            let flags = Int32(ptr.memory.ifa_flags)
            let addr = ptr.memory.ifa_addr.memory

            // Check for running IPv4, IPv6 interfaces. Skip the loopback interface.
            if (flags & (IFF_UP|IFF_RUNNING|IFF_LOOPBACK)) == (IFF_UP|IFF_RUNNING) {
                if addr.sa_family == UInt8(AF_INET) || addr.sa_family == UInt8(AF_INET6) {

                    // Convert interface address to a human readable string:
                    var hostname = [CChar](count: Int(NI_MAXHOST), repeatedValue: 0)
                    if (getnameinfo(ptr.memory.ifa_addr, socklen_t(addr.sa_len), &hostname, socklen_t(hostname.count),
                        nil, socklen_t(0), NI_NUMERICHOST) == 0) {
                        if let address = String.fromCString(hostname) {
                            addresses.append(address)
                        }
                    }
                }
            }
        }
        freeifaddrs(ifaddr)
    }

    return addresses
}

---

Update for Swift 3: In addition to adopting the code to the many changes in Swift 3, iterating over all interfaces can now use the new generalized sequence() function:

func getIFAddresses() -> [String] {
    var addresses = [String]()

    // Get list of all interfaces on the local machine:
    var ifaddr : UnsafeMutablePointer<ifaddrs>?
    guard getifaddrs(&ifaddr) == 0 else { return [] }
    guard let firstAddr = ifaddr else { return [] }

    // For each interface ...
    for ptr in sequence(first: firstAddr, next: { $0.pointee.ifa_next }) {
        let flags = Int32(ptr.pointee.ifa_flags)
        let addr = ptr.pointee.ifa_addr.pointee

        // Check for running IPv4, IPv6 interfaces. Skip the loopback interface.
        if (flags & (IFF_UP|IFF_RUNNING|IFF_LOOPBACK)) == (IFF_UP|IFF_RUNNING) {
            if addr.sa_family == UInt8(AF_INET) || addr.sa_family == UInt8(AF_INET6) {

                // Convert interface address to a human readable string:
                var hostname = [CChar](repeating: 0, count: Int(NI_MAXHOST))
                if (getnameinfo(ptr.pointee.ifa_addr, socklen_t(addr.sa_len), &hostname, socklen_t(hostname.count),
                                nil, socklen_t(0), NI_NUMERICHOST) == 0) {
                    let address = String(cString: hostname)
                    addresses.append(address)
                }
            }
        }
    }

    freeifaddrs(ifaddr)
    return addresses
}

Answer 5

Answering to Is there an alternative way to getifaddrs() for getting the ip-address?

Yes, there is an alternative way. You can also get the ip address by utilizing ioctl(). The cleanest way would be doing it in C and then wrapping it up in Swift. So consider this:

Create a C Source File (Xcode should create it together with a .h) and remember adding the header into your project's bridging header, or into umbrella-header if you have a cocoa touch framework.

Add the following into your .c source and method's declaration into .h:

#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>

int _interfaceAddressForName(char* interfaceName, struct sockaddr* interfaceAddress) {

    struct ifreq ifr;
    int fd = socket(AF_INET, SOCK_DGRAM, 0);
    ifr.ifr_addr.sa_family = AF_INET;

    strncpy(ifr.ifr_name, interfaceName, IFNAMSIZ-1);

    int ioctl_res;
    if ( (ioctl_res = ioctl(fd, SIOCGIFADDR, &ifr)) < 0){
        return ioctl_res;
    }

    close(fd);
    memcpy(interfaceAddress, &ifr.ifr_addr, sizeof(struct sockaddr));
    return 0;
}

Your Swift wrapper might look something like:

public enum Error:ErrorType {
    case IOCTLFailed(Int32)
    case StringIsNotAnASCIIString
}

public func interfaceAddress(forInterfaceWithName interfaceName: String) throws -> sockaddr_in {

    guard let cString = interfaceName.cStringUsingEncoding(NSASCIIStringEncoding) else {
        throw Error.StringIsNotAnASCIIString
    }

    let addressPtr = UnsafeMutablePointer<sockaddr>.alloc(1)
    let ioctl_res = _interfaceAddressForName(strdup(cString), addressPtr)
    let address = addressPtr.move()
    addressPtr.dealloc(1)

    if ioctl_res < 0 {
        throw Error.IOCTLFailed(errno)
    } else {
        return unsafeBitCast(address, sockaddr_in.self)
    }
}

Then you can use it in your code like:

let interfaceName = "en0"
do {
    let wlanInterfaceAddress = try interfaceAddress(forInterfaceWithName: interfaceName)
    print(String.fromCString(inet_ntoa(wlanInterfaceAddress.sin_addr))!)
} catch {
    if case Error.IOCTLFailed(let errno) = error where errno == ENXIO {
        print("interface(\(interfaceName)) is not available")
    } else {
        print(error)
    }
}

en0 typically is the interface you need, which stands for WLAN

If you also need to know available interface names you can utilize if_indextoname():

public func interfaceNames() -> [String] {

    let MAX_INTERFACES = 128;

    var interfaceNames = [String]()
    let interfaceNamePtr = UnsafeMutablePointer<Int8>.alloc(Int(IF_NAMESIZE))
    for interfaceIndex in 1...MAX_INTERFACES {
        if (if_indextoname(UInt32(interfaceIndex), interfaceNamePtr) != nil){
            if let interfaceName = String.fromCString(interfaceNamePtr) {
                interfaceNames.append(interfaceName)
            }
        } else {
            break
        }
    }

    interfaceNamePtr.dealloc(Int(IF_NAMESIZE))
    return interfaceNames
}