Get peer IP address and port on OSX in objective-c from NSStream, CFStream or Socket

Question

I have written a server that listens on a specific port for incoming tcp connections. To manage the network connectivity I am using Streams (CFStream/NSStream). When a connection is esthablished I save all the information about this very connection in another instance of a dedicated class which is also set as the delegate for the streams.

Now I want to get the public IP of the device that sends me a message through the already esthablished streams, in other words, I would like to store the IP of the stream's peer. I tried many things, but unfortunately I only get null-values.

Is there a possibility to get the peer's address (ip and port) from an existing stream of the described form?

Here is some code I have tried:

CFDataRef peerAddress = CFSocketCopyPeerAddress(_sockRef);
// _sockRef is saved when connection is established in listening callback and is not null

I also tried to get the information direct in the listening callback method:

NSData *peer = nil;

CFSocketNativeHandle nativeSocketHandle = *(CFSocketNativeHandle *)data;

struct sockaddr *addressinfo = NULL;

uint8_t name[SOCK_MAXADDRLEN];

socklen_t namelen = sizeof(addressinfo);
int result = getpeername(nativeSocketHandle, addressinfo, &namelen);

if (result == 0) {

      peer = [NSData dataWithBytes:name length:namelen];

 }

struct sockaddr_in *s = (struct sockaddr_in*)name;

char *ipstr = malloc(INET_ADDRSTRLEN);

ipstr = inet_ntoa(s->sin_addr); // is 0.0.0.0 :-(

And I tried another method:

_publicIP = CFWriteStreamCopyProperty((__bridge CFWriteStreamRef)(_writeStream), kCFStreamPropertySocketRemoteHostName);

Why do I always get null-values? Can anyone help me?

Thank you in advance!

Answer 1

Okay I figured it out by now. This is what I did:

- (void)getPublicClientAddress {
    // Get public IP from stream

    // Get hands on appropriate data structures via the socket number
    CFSocketNativeHandle nativeSocketHandle = _socketnumber;
    uint8_t name[SOCK_MAXADDRLEN];
    socklen_t namelen = sizeof(name);
    NSData *peer = nil;
    if (0 == getpeername(nativeSocketHandle, (struct sockaddr *)name, &namelen)) {
        peer = [NSData dataWithBytes:name length:namelen];
    }

    if (_ipv6){
        // If ipv6 is used
        struct sockaddr_in6 *socketaddress = (struct sockaddr_in6*)name;

        // convert ip to string
        char *ipstr = malloc(INET6_ADDRSTRLEN);
        struct in6_addr *ipv6addr = &socketaddress->sin6_addr;
        inet_ntop(AF_INET6, ipv6addr, ipstr, sizeof(ipstr));

        // convert port to int
        int portnumber = socketaddress->sin6_port;

        // Save in properties
        _publicIP   = [NSString stringWithFormat:@"%s", ipstr];
        _publicPort = [NSString stringWithFormat:@"%d", portnumber];
    } else {
        // If ipv4 is used
        struct sockaddr_in *socketaddress = (struct sockaddr_in*)name;

        // convert ip to string
        char *ipstr = malloc(INET_ADDRSTRLEN);
        struct in_addr *ipv4addr = &socketaddress->sin_addr;
        ipstr = inet_ntoa(*ipv4addr);
        //inet_ntop(AF_INET, ipv4addr, ipstr, sizeof(ipstr));

        // convert port to int
        int portnumber = socketaddress->sin_port;

        // Save in properties
        _publicIP   = [NSString stringWithFormat:@"%s", ipstr];
        _publicPort = [NSString stringWithFormat:@"%d", portnumber];
    }
}

Afterwards you will have the public IP in the property _publicIP and the public port in the property _publicPort. All information is gathered from a connection on the server side.

I hope this post will help someone =)