Reading Atom feed of gmail account from C#

Question

I have a project that will send an email with certain data to a gmail account. I think that it will probably be easier to read the Atom feed rather than connect through POP.

The url that I should be using according to Google is:

https://gmail.google.com/gmail/feed/atom

The question/problem is: how do I authenticate the email account I want to see? If I do it in Firefox, it uses the cookies.

I'm also uncertain how exactly to "download" the XML file that this request should return (I believe the proper term is stream).

Edit 1:

I am using .Net 3.5.

Answer 1

This is what I used in Vb.net:

objClient.Credentials = New System.Net.NetworkCredential(username, password)

objClient is of type System.Net.WebClient.

You can then get the emails from the feed using something like this:

Dim nodelist As XmlNodeList
Dim node As XmlNode
Dim response As String
Dim xmlDoc As New XmlDocument

'get emails from gmail
response = Encoding.UTF8.GetString(objClient.DownloadData("https://mail.google.com/mail/feed/atom"))
response = response.Replace("<feed version=""0.3"" xmlns=""http://purl.org/atom/ns#"">", "<feed>")

'Get the number of unread emails
xmlDoc.LoadXml(response)
node = xmlDoc.SelectSingleNode("/feed/fullcount")
mailCount = node.InnerText
nodelist = xmlDoc.SelectNodes("/feed/entry")
node = xmlDoc.SelectSingleNode("title")

This should not be very different in C#.

Answer 2

.NET framework 3.5 provides native classes to read feeds. This articles describes how to do it.

I haven't used it tho, but there must be some provision for authentication to a URL. You can check that out. I too will do it, and post the answer back.

If you are not using framework 3.5, then you can try Atom.NET. I have used it once, but its old. You can give it a try if it meets your needs.

EDIT: This is the code for assigning user credentials:

XmlUrlResolver resolver = new XmlUrlResolver();
resolver.Credentials = new NetworkCredential("[email protected]", "password");

XmlReaderSettings settings = new XmlReaderSettings();
settings.XmlResolver = resolver;

XmlReader reader = XmlReader.Create("https://gmail.google.com/gmail/feed/atom", settings);

Answer 3

You use Basic Auth. Basically, you make an initial request, the server replies with 401, and then you send back the password in base64 (in this case over HTTPS).

Note though that:

1. The feed only allows you to get trivial info about the account (e.g. new mail). It does not allow you to send messages.
2. POP can not be used to send messages either.
3. Usually SMTP is used, and it really isn't that hard.

EDIT: Here's an example for authenticating and loading the Atom feed into an XmlDocument. Note though that will only provide read access. Search or ask another question for info on C# and SMTP. The ICertificatePolicy junk was necessary for me as Mono didn't like Google's certificate. It's a quick workaround, not suitable for production.

Okay, since you've clarified you're actually reading mail (and a different component is sending it), I recommend you do use POP. :

using System;
using System.Net;
using System.IO;
using System.Security.Cryptography.X509Certificates;
using System.Xml;

public class GmailFeed
{
    private class IgnoreBadCerts : ICertificatePolicy
    {
        public bool CheckValidationResult (ServicePoint sp, 
                                           X509Certificate certificate, 
                                           WebRequest request, 
                                           int error)
        {
            return true;
        }


    }

    public static void Main(string[] argv)
    {
        if(argv.Length != 2)
        {
            Console.Error.WriteLine("Usage: GmailFeed username password");
            Environment.ExitCode = 1;
            return;
        }
        ServicePointManager.CertificatePolicy = new IgnoreBadCerts();

        NetworkCredential cred = new NetworkCredential();
        cred.UserName = argv[0];
        cred.Password = argv[1];

        WebRequest req = WebRequest.Create("https://gmail.google.com/gmail/feed/atom");
        req.Credentials = cred;
        Stream resp = req.GetResponse().GetResponseStream();

        XmlReader reader = XmlReader.Create(resp);
        XmlDocument doc = new XmlDocument();
        doc.Load(reader);
    }
}