Get current IP address

Jume · October 2008

how?

thanks,
Jume

gradha · October 2008

Haven't tried it myself, but this might tell you how: Day 4.

Jume · October 2008

gradha;24330 said:
Haven't tried it myself, but this might tell you how: Day 4.

figured it out later today with some lo level network code, but will definitely look at this. I guess there must be an easier way of finding it then how I did it. I'll also post my code if anyone's interested.

Thanks gradha,
Jume

Software-Diner.de · October 2008

I would be interested...the "day-4-code" is - judged by some other posts - not the "officially supported way"...at least they say so :-)

Just in case it wont survive the next OS or SDK update it would be cool to have another way to get your own ip!

Jume · October 2008

Software-Diner.de;24341 said:
I would be interested...the "day-4-code" is - judged by some other posts - not the "officially supported way"...at least they say so :-)

Just in case it wont survive the next OS or SDK update it would be cool to have another way to get your own ip!

I'll post my code tomorrow when I'm back in the office. Actually my could also be stop working at some time, you never know what apple does with next SDK release.

Jume · October 2008

Ok so here we go. I used some code that was running for macs and changed it so it is working on iPhone to to get the local IP addresses from iPhone.

It's simply C. So to get started I created IPAddress.h and IPAddress.c

IPAdress.h

#define MAXADDRS	32

extern char *if_names[MAXADDRS];
extern char *ip_names[MAXADDRS];
extern char *hw_addrs[MAXADDRS];
extern unsigned long ip_addrs[MAXADDRS];

// Function prototypes

void InitAddresses();
void FreeAddresses();
void GetIPAddresses();
void GetHWAddresses();

IPAddress.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/sockio.h>
#include <net/if.h>
#include <errno.h>
#include <net/if_dl.h>

#include \"GetAddresses.h\"

#define	min(a,b)	((a) < (b) ? (a) : (b))
#define	max(a,b)	((a) > (b) ? (a) : (b))

#define BUFFERSIZE	4000

char *if_names[MAXADDRS];
char *ip_names[MAXADDRS];
char *hw_addrs[MAXADDRS];
unsigned long ip_addrs[MAXADDRS];

static int   nextAddr = 0;

void InitAddresses()
{
	int i;
	for (i=0; i<MAXADDRS; ++i)
	{
		if_names[i] = ip_names[i] = hw_addrs[i] = NULL;
		ip_addrs[i] = 0;
	}
}

void FreeAddresses()
{
	int i;
	for (i=0; i<MAXADDRS; ++i)
	{
		if (if_names[i] != 0) free(if_names[i]);
		if (ip_names[i] != 0) free(ip_names[i]);
		if (hw_addrs[i] != 0) free(hw_addrs[i]);
		ip_addrs[i] = 0;
	}
	InitAddresses();
}

void GetIPAddresses()
{
	int                 i, len, flags;
	char                buffer[BUFFERSIZE], *ptr, lastname[IFNAMSIZ], *cptr;
	struct ifconf       ifc;
	struct ifreq        *ifr, ifrcopy;
	struct sockaddr_in	*sin;

	char temp[80];

	int sockfd;

	for (i=0; i<MAXADDRS; ++i)
	{
		if_names[i] = ip_names[i] = NULL;
		ip_addrs[i] = 0;
	}

	sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if (sockfd < 0)
	{
		perror(\"socket failed\");
		return;
	}
	
	ifc.ifc_len = BUFFERSIZE;
	ifc.ifc_buf = buffer;
	
	if (ioctl(sockfd, SIOCGIFCONF, &ifc) < 0)
	{
		perror(\"ioctl error\");
		return;
	}
	
	lastname[0] = 0;
	
	for (ptr = buffer; ptr < buffer + ifc.ifc_len; )
	{
		ifr = (struct ifreq *)ptr;
		len = max(sizeof(struct sockaddr), ifr->ifr_addr.sa_len);
		ptr += sizeof(ifr->ifr_name) + len;	// for next one in buffer
	
		if (ifr->ifr_addr.sa_family != AF_INET)
		{
			continue;	// ignore if not desired address family
		}
	
		if ((cptr = (char *)strchr(ifr->ifr_name, ':')) != NULL)
		{
			*cptr = 0;		// replace colon will null
		}
	
		if (strncmp(lastname, ifr->ifr_name, IFNAMSIZ) == 0)
		{
			continue;	/* already processed this interface */
		}
	
		memcpy(lastname, ifr->ifr_name, IFNAMSIZ);
	
		ifrcopy = *ifr;
		ioctl(sockfd, SIOCGIFFLAGS, &ifrcopy);
		flags = ifrcopy.ifr_flags;
		if ((flags & IFF_UP) == 0)
		{
			continue;	// ignore if interface not up
		}
	
		if_names[nextAddr] = (char *)malloc(strlen(ifr->ifr_name)+1);
		if (if_names[nextAddr] == NULL)
		{
			return;
		}
		strcpy(if_names[nextAddr], ifr->ifr_name);
	
		sin = (struct sockaddr_in *)&ifr->ifr_addr;
		strcpy(temp, inet_ntoa(sin->sin_addr));
	
		ip_names[nextAddr] = (char *)malloc(strlen(temp)+1);
		if (ip_names[nextAddr] == NULL)
		{
			return;
		}
		strcpy(ip_names[nextAddr], temp);

		ip_addrs[nextAddr] = sin->sin_addr.s_addr;

		++nextAddr;
	}
	
	close(sockfd);
}

void GetHWAddresses()
{
   struct ifconf ifc;
   struct ifreq *ifr;
   int i, sockfd;
   char buffer[BUFFERSIZE], *cp, *cplim;
   char temp[80];

   for (i=0; i<MAXADDRS; ++i)
   {
      hw_addrs[i] = NULL;
   }

   sockfd = socket(AF_INET, SOCK_DGRAM, 0);
   if (sockfd < 0)
   {
      perror(\"socket failed\");
      return;
   }

   ifc.ifc_len = BUFFERSIZE;
   ifc.ifc_buf = buffer;

   if (ioctl(sockfd, SIOCGIFCONF, (char *)&ifc) < 0)
   {
      perror(\"ioctl error\");
      close(sockfd);
	  return;
   }

   ifr = ifc.ifc_req;

   cplim = buffer + ifc.ifc_len;

   for (cp=buffer; cp < cplim; )
   {
      ifr = (struct ifreq *)cp;
	  if (ifr->ifr_addr.sa_family == AF_LINK)
	  {
	     struct sockaddr_dl *sdl = (struct sockaddr_dl *)&ifr->ifr_addr;
		 int a,b,c,d,e,f;
		 int i;

		 strcpy(temp, (char *)ether_ntoa(LLADDR(sdl)));
		 sscanf(temp, \"%x:%x:%x:%x:%x:%x\", &a, &b, &c, &d, &e, &f);
         sprintf(temp, \"%02X:%02X:%02X:%02X:%02X:%02X\",a,b,c,d,e,f);

		 for (i=0; i<MAXADDRS; ++i)
		 {
		    if ((if_names[i] != NULL) && (strcmp(ifr->ifr_name, if_names[i]) == 0))
			{
			   if (hw_addrs[i] == NULL)
			   {
   			      hw_addrs[i] = (char *)malloc(strlen(temp)+1);
				  strcpy(hw_addrs[i], temp);
				  break;
			   }
			}
		}
	  }
      cp += sizeof(ifr->ifr_name) + max(sizeof(ifr->ifr_addr), ifr->ifr_addr.sa_len);
   }

   close(sockfd);
}

And then I use it like this in myAppDelegate

MyAppAppDelegate.h


#import <UIKit/UIKit.h>

@interface MyAppAppDelegate : NSObject <UIApplicationDelegate> {
	NSString *localIP;
}

@property (nonatomic, retain) NSString *localIP;

- (NSString *)deviceIPAdress;

@end

MyAppDelegate.m


- (void)applicationDidFinishLaunching:(UIApplication *)application {
	self.localIP = [self deviceIPAdress];

        ...
}

- (NSString *)deviceIPAdress {
	InitAddresses();
	GetIPAddresses();
	GetHWAddresses();
	
        /* 
	int i;
	NSString *deviceIP;
	for (i=0; i<MAXADDRS; ++i)
	{
		static unsigned long localHost = 0x7F000001;		// 127.0.0.1
		unsigned long theAddr;
		
		theAddr = ip_addrs[i];
		
		if (theAddr == 0) break;
		if (theAddr == localHost) continue;
		
		NSLog(@\"%s %s %s\n\", if_names[i], hw_addrs[i], ip_names[i]);
	}
	deviceIP = [NSString stringWithFormat:@\"%s\", ip_names[i]];
	*/
	
        //this will get you the right IP from your device in format like 198.111.222.444. If you use the for loop above you will se that ip_names array will also contain localhost IP 127.0.0.1 that's why I don't use it. Eventualy this was code from mac that's why it uses arrays for ip_names as macs can have multiple IPs
	return [NSString stringWithFormat:@\"%s\", ip_names[1]];
}

Software-Diner.de · October 2008

Jume,

thanks for sharing this. I understand now why you think this seems complicated... :-)

But I think it will help nevertheless...it's always good to see other solutions to learn how things can be done!

bye, Markus.

Jume · October 2008

Software-Diner.de;24459 said:
Jume,

thanks for sharing this. I understand now why you think this seems complicated... :-)

But I think it will help nevertheless...it's always good to see other solutions to learn how things can be done!

bye, Markus.

Network code on Mac is always complicated :). But this definitely works and I think should work as it really uses basic C socket functions.

gradha · October 2008

Looking through the docs it looked like the official way to get the host address would be to use Core Foundation's CFHost, which OTOH is possibly a prettier version of the C code you just posted.

dietrichuhl · February 2009

Jume;24461 said:
Network code on Mac is always complicated :). But this definitely works and I think should work as it really uses basic C socket functions.

I have not had my C programming Hat on in years.
Does this code pull the available connections in the process of determining your IP address?

Im trying to simply see the connections available or otherwise that exist around the iDevice. I want to build a crude location marker system for iDevices that do not have GPS and are not in Location Services registered areas or do not have a wifi connection.

I dont need to access to the networks I just need to know what networks are around the unit. Relative strength would be a plus. But just seeing them would be a start.

Any thoughts on where to look up code or other reference material would be appreciated.

Thanks
Dietrich

kurisukun · May 2009

Sorry to bring up this old question, but I've been trying to figure out how to use the "official way" to find out the iPhone's current IP address using CFHost.

However, I haven't been able to successfully do so yet. While I'm sure the above code works, any help with the CFHost version would be much appreciated!

jtara · May 2009

I don't know that there's an "official way" to do this.

The low-level BSD (er, Darwin, er, iPhone OS...) OS calls are fair play, and I think a lot of iPhone developers don't realize that.

smasher · May 2009

kurisukun;85818 said:
Sorry to bring up this old question, but I've been trying to figure out how to use the "official way" to find out the iPhone's current IP address using CFHost.

However, I haven't been able to successfully do so yet. While I'm sure the above code works, any help with the CFHost version would be much appreciated!

Just curious why you want the IP address - it's going to change when someone moves from network to network, and when someone goes from cell to wifi. I hope you've planned for that situation.

Jume · May 2009

kurisukun;85818 said:
Sorry to bring up this old question, but I've been trying to figure out how to use the "official way" to find out the iPhone's current IP address using CFHost.

However, I haven't been able to successfully do so yet. While I'm sure the above code works, any help with the CFHost version would be much appreciated!

Try this method: 31 Days of iPhone SDK Apps - Day 04: What is my IP? | Apps Amuck Blog

it's a little shorter than my method described above ...

Menneisyys · May 2010

Note that this NSHost-based hack doesn't seem to work under 4.0 any more. (Tested under b4.)

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