IPAddress.Parse() using port on IPv4

Question

I'm trying to parse a string containing an IP address and a port using IPAddress.Parse. This works well with IPv6 addresses but not with IPv4 addresses. Can somone explain why this happens?

The code I'm using is:

IPAddress.Parse("[::1]:5"); //Valid
IPAddress.Parse("127.0.0.1:5"); //null

Answer 1

Uri url;
IPAddress ip;
if (Uri.TryCreate(String.Format("http://{0}", "127.0.0.1:5"), UriKind.Absolute, out url) &&
   IPAddress.TryParse(url.Host, out ip))
{
    IPEndPoint endPoint = new IPEndPoint(ip, url.Port);
}

Answer 2

This happens because the port is not part of the IP address. It belongs to TCP/UDP, and you'll have to strip it out first. The Uri class might be helpful for this.

Answer 3

IPAddress is not IP+Port. You want IPEndPoint.

Example from http://www.java2s.com/Code/CSharp/Network/ParseHostString.htm

public static void ParseHostString(string hostString, ref string hostName, ref int port)
{
   hostName = hostString;
   if (hostString.Contains(":"))
   {
      string[] hostParts = hostString.Split(':');

      if (hostParts.Length == 2)
      {
         hostName = hostParts[0];
         int.TryParse(hostParts[1], out port);
      }
   }
}

Edit: Ok, I'll admit that wasn't the most elegant solution. Try this one I wrote (just for you) instead:

// You need to include some usings:
using System.Text.RegularExpressions;
using System.Net;

// Then this code (static is not required):
private static Regex hostPortMatch = new Regex(@"^(?<ip>(?:\[[\da-fA-F:]+\])|(?:\d{1,3}\.){3}\d{1,3})(?::(?<port>\d+))?$", System.Text.RegularExpressions.RegexOptions.Compiled);
public static IPEndPoint ParseHostPort(string hostPort)
{
   Match match = hostPortMatch.Match(hostPort);
   if (!match.Success)
      return null;

   return new IPEndPoint(IPAddress.Parse(match.Groups["ip"].Value), int.Parse(match.Groups["port"].Value));
}

Note that this one ONLY accepts IP address, not hostname. If you want to support hostname you'll either have to resolve it to IP or not use IPAddress/IPEndPoint.

Answer 4

IPAddress.Parse is meant to take A string that contains an IP address in dotted-quad notation for IPv4 and in colon-hexadecimal notation for IPv6. So your first example works for IPv6 and your second example fails because it doesnt support a port for IPv4. Link http://msdn.microsoft.com/en-us/library/system.net.ipaddress.parse.aspx