How to check private/local IP address by using regular expression

Question

Hope all of you will be fine. I am building an IOS application in which I warn the user if they typed a private/local IP address in text-field. I have searched on internet and found it done in the Android app using regular expression: Java: (127.0.0.1)|(192.168.$) | (172.1[6-9].$) | (172.2[0-9].$) | (172.3[0-1].$) | (10.*$)

I want the same regular expression for IOS application but I don't know how to code it. I searched on internet and found Private IP Address Identifier in Regular Expression but i could not understand it. I just know some objective-c. Can some one help me in this regard please.

Ok guys finally I think I have solved the problem by following code.

-(void)CheckIP
{
    NSError *error = NULL;
    NSString *pattern = @"(127.0.0.1)|(192.168.$)|(172.1[6-9].$)|(172.2[0-9].$)|(172.3[0-1].$)|(10.*$)";     // "[a-zA-Z]+[,]\\s*([A-Z]{2})";
    NSString *string = self.tfExternalHost.text;
    NSRange range = NSMakeRange(0, string.length);
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:&error];
    NSArray *matches = [regex matchesInString:string options:NSMatchingProgress range:range];
    NSLog(@" Found Match %@", matches);
}

Suggest me if the above code can be improved.

You have the regular expression. Do some research on the `NSRegularExpression` class. — rmaddy, Nov 06 '15 at 05:26
hi please see this link to your reference http://stackoverflow.com/a/10971521/2910061 — Ilesh P, Nov 06 '15 at 05:36
thanks to all of you for your response. Let me try it and then i will inform you. — Zeebok, Nov 06 '15 at 05:38
Dear @ilesh, Thanks for your response. Your provided refrence is for validation of an IP address with regular expression. I need a code that can check either ip address is not private or local IP. Can you help me in this regard. — Zeebok, Nov 06 '15 at 05:43

score 3 · Accepted Answer · edited Aug 24 '17 at 11:51

3

I have solved the problem.

-(BOOL)CheckIPAddress
{
    // this code is to check either user entered local/private ip-address
    NSError *error = NULL;    
    NSString *pattern = @"((127\.)|(10\.)|(172\.1[6-9]\.)|(172\.2[0-9]\.)|(172\.3[0-1]\.)|(192\.168\.))";
    NSString *string = self.tfExternalHost.text;
    NSRange range = NSMakeRange(0, string.length);
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:&error];
    NSArray *matches = [regex matchesInString:string options:NSMatchingProgress range:range];
    if (matches.count>0) {
        UIAlertView *simpleAlert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@"Warning", nil) message:NSLocalizedString(@"Please provide valid external IP address.", nil) delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [simpleAlert show];
        return true;
    }
    return false;
}

edited Aug 24 '17 at 11:51

SiHa

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answered Nov 06 '15 at 09:22

Zeebok

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Instead of : NSString *pattern = @"((127\.)|(10\.)|(172\.1[6-9]\.)|(172\.2[0-9]\.)|(172\.3[0-1]\.)|(192\.168\.))"; It should be: @"((127\\.)|(10\\.)|(172\\.1[6-9]\\.)|(172\\.2[0-9]\\.)|(172\\.3[0-1]\\.)|(192\\.168\\.))" – Antoine Rosset Jun 07 '16 at 11:42
What about IPv6? @Zeebok – Jaybo Oct 11 '16 at 09:27
@Zeebok: new answer with ipv6 support posted below – xaphod Nov 11 '16 at 17:52

score 2 · Answer 2 · answered Nov 11 '16 at 17:51

I needed IPv6 support as well, so here's my answer. Also, note that iOS regexs should have escaped backslashes as Antoine pointed out.

Here's a category for NSString which returns YES if it's a local / private IP address. Note that this code assumes the string is a valid IP address (ie. it will match 192.168.chocolate.sundae)

    - (BOOL)isPrivateIPAddress {
        NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(^127\\.)|(^192\\.168\\.)|(^10\\.)|(^172\\.1[6-9]\\.)|(^172\\.2[0-9]\\.)|(^172\\.3[0-1]\\.)|(^::1$)|(^[fF][cCdD])" options:0 error:nil];
        NSArray *matches = [regex matchesInString:self options:0 range:NSMakeRange(0, self.length)];
        if (matches.count > 0)
            return YES;
        return NO;
    }

Buyer-beware: I only did limited testing of this.

How to check private/local IP address by using regular expression

2 Answers2