Best way to create IPEndpoint from string

Question

Since IPEndpoint contains a ToString() method that outputs:

10.10.10.10:1010

There should also be

Answer 1

This will do IPv4 and IPv6. An extension method for this functionality would be on System.string. Not sure I want this option for every string I have in the project.

private static IPEndPoint IPEndPointParse(string endpointstring)
{
    string[] values = endpointstring.Split(new char[] {':'});

    if (2 > values.Length)
    {
        throw new FormatException("Invalid endpoint format");
    }

    IPAddress ipaddress;
    string ipaddressstring = string.Join(":", values.Take(values.Length - 1).ToArray());
    if (!IPAddress.TryParse(ipaddressstring, out ipaddress))
    {
        throw new FormatException(string.Format("Invalid endpoint ipaddress '{0}'", ipaddressstring));
    }

    int port;
    if (!int.TryParse(values[values.Length - 1], out port)
     || port < IPEndPoint.MinPort
     || port > IPEndPoint.MaxPort)
    {
        throw new FormatException(string.Format("Invalid end point port '{0}'", values[values.Length - 1]));
    }

    return new IPEndPoint(ipaddress, port);
}

Answer 2

Apparently, IPEndPoint.Parse and IPEndPoint.TryParse were added in .NET Core 3.0.

In case you're targeting it, give those methods a try! The implementation is seen in the link above.

Answer 3

I had the requirement of parsing an IPEndpoint with IPv6, v4 and hostnames. The solution I wrote is listed below:

    public static IPEndPoint Parse(string endpointstring)
    {
        return Parse(endpointstring, -1);
    }

    public static IPEndPoint Parse(string endpointstring, int defaultport)
    {
        if (string.IsNullOrEmpty(endpointstring)
            || endpointstring.Trim().Length == 0)
        {
            throw new ArgumentException("Endpoint descriptor may not be empty.");
        }

        if (defaultport != -1 &&
            (defaultport < IPEndPoint.MinPort
            || defaultport > IPEndPoint.MaxPort))
        {
            throw new ArgumentException(string.Format("Invalid default port '{0}'", defaultport));
        }

        string[] values = endpointstring.Split(new char[] { ':' });
        IPAddress ipaddy;
        int port = -1;

        //check if we have an IPv6 or ports
        if (values.Length <= 2) // ipv4 or hostname
        {
            if (values.Length == 1)
                //no port is specified, default
                port = defaultport;
            else
                port = getPort(values[1]);

            //try to use the address as IPv4, otherwise get hostname
            if (!IPAddress.TryParse(values[0], out ipaddy))
                ipaddy = getIPfromHost(values[0]);
        }
        else if (values.Length > 2) //ipv6
        {
            //could [a:b:c]:d
            if (values[0].StartsWith("[") && values[values.Length - 2].EndsWith("]"))
            {
                string ipaddressstring = string.Join(":", values.Take(values.Length - 1).ToArray());
                ipaddy = IPAddress.Parse(ipaddressstring);
                port = getPort(values[values.Length - 1]);
            }
            else //[a:b:c] or a:b:c
            {
                ipaddy = IPAddress.Parse(endpointstring);
                port = defaultport;
            }
        }
        else
        {
            throw new FormatException(string.Format("Invalid endpoint ipaddress '{0}'", endpointstring));
        }

        if (port == -1)
            throw new ArgumentException(string.Format("No port specified: '{0}'", endpointstring));

        return new IPEndPoint(ipaddy, port);
    }

    private static int getPort(string p)
    {
        int port;

        if (!int.TryParse(p, out port)
         || port < IPEndPoint.MinPort
         || port > IPEndPoint.MaxPort)
        {
            throw new FormatException(string.Format("Invalid end point port '{0}'", p));
        }

        return port;
    }

    private static IPAddress getIPfromHost(string p)
    {
        var hosts = Dns.GetHostAddresses(p);

        if (hosts == null || hosts.Length == 0)
            throw new ArgumentException(string.Format("Host not found: {0}", p));

        return hosts[0];
    }

This has been tested to work with the following examples:

• 0.0.0.0:100
• 0.0.0.0
• [::1]:100
• [::1]
• ::1
• [a:b:c:d]
• [a:b:c:d]:100
• example.org
• example.org:100

Answer 4

Here is my version of parsing text to IPEndPoint:

private static IPEndPoint ParseIPEndPoint(string text)
{
    Uri uri;
    if (Uri.TryCreate(text, UriKind.Absolute, out uri))
        return new IPEndPoint(IPAddress.Parse(uri.Host), uri.Port < 0 ? 0 : uri.Port);
    if (Uri.TryCreate(String.Concat("tcp://", text), UriKind.Absolute, out uri))
        return new IPEndPoint(IPAddress.Parse(uri.Host), uri.Port < 0 ? 0 : uri.Port);
    if (Uri.TryCreate(String.Concat("tcp://", String.Concat("[", text, "]")), UriKind.Absolute, out uri))
        return new IPEndPoint(IPAddress.Parse(uri.Host), uri.Port < 0 ? 0 : uri.Port);
    throw new FormatException("Failed to parse text to IPEndPoint");
}

Tested with:

• 0.0.0.0
• 0.0.0.0:100
• [::1]:100
• [::1]:0
• ::1
• [2001:db8:85a3:8d3:1319:8a2e:370:7348]
• [2001:db8:85a3:8d3:1319:8a2e:370:7348]:100
• http://0.0.0.0
• http://0.0.0.0:100
• http://[::1]
• http://[::1]:100
• https://0.0.0.0
• https://[::1]

Answer 5

If the port number is always provided after a ':', the following method may be a more elegant option (in code length instead of efficiency).

public static IPEndpoint ParseIPEndpoint(string ipEndPoint) {
    int ipAddressLength = ipEndPoint.LastIndexOf(':');
    return new IPEndPoint(
        IPAddress.Parse(ipEndPoint.Substring(0, ipAddressLength)),
        Convert.ToInt32(ipEndPoint.Substring(ipAddressLength + 1)));
}

It works fine for my simple application without considering complex IP address format.

Answer 6

The parsing code is simple for an IPv4 endpoint, but IPEndPoint.ToString() on an IPv6 address also uses the same colon notation, but conflicts with the IPv6 address's colon notation. I was hoping Microsoft would spend the effort writing this ugly parsing code instead, but I guess I'll have to...