UserAgentDetectionLib.cs

using System;

namespace IdentityServer
{
    public class UserAgentDetectionLib
    {
        public static bool DisallowsSameSiteNone(string userAgent)
        {
            // Check if a null or empty string has been passed in, since this
            // will cause further interrogation of the useragent to fail.
            if (String.IsNullOrWhiteSpace(userAgent))
                return false;

            // Cover all iOS based browsers here. This includes:
            // - Safari on iOS 12 for iPhone, iPod Touch, iPad
            // - WkWebview on iOS 12 for iPhone, iPod Touch, iPad
            // - Chrome on iOS 12 for iPhone, iPod Touch, iPad
            // All of which are broken by SameSite=None, because they use the iOS networking
            // stack.
            if (userAgent.Contains("CPU iPhone OS 12") ||
                userAgent.Contains("iPad; CPU OS 12"))
            {
                return true;
            }

            // Cover Mac OS X based browsers that use the Mac OS networking stack. 
            // This includes:
            // - Safari on Mac OS X.
            // This does not include:
            // - Chrome on Mac OS X
            // Because they do not use the Mac OS networking stack.
            if (userAgent.Contains("Macintosh; Intel Mac OS X 10_14") &&
                userAgent.Contains("Version/") && userAgent.Contains("Safari"))
            {
                return true;
            }

            // Cover Chrome 50-69, because some versions are broken by SameSite=None, 
            // and none in this range require it.
            // Note: this covers some pre-Chromium Edge versions, 
            // but pre-Chromium Edge does not require SameSite=None.
            if (userAgent.Contains("Chrome/5") || userAgent.Contains("Chrome/6"))
            {
                return true;
            }

            return false;
        }
    }
}