server/src/Notifications/Controllers/SendController.cs

using System.Text;
using Bit.Core.Utilities;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.SignalR;

namespace Bit.Notifications
{
    [Authorize("Internal")]
    public class SendController : Controller
    {
        private readonly IHubContext<NotificationsHub> _hubContext;

        public SendController(IHubContext<NotificationsHub> hubContext)
        {
            _hubContext = hubContext;
        }

        [HttpPost("~/send")]
        [SelfHosted(SelfHostedOnly = true)]
        public async Task PostSend()
        {
            using (var reader = new StreamReader(Request.Body, Encoding.UTF8))
            {
                var notificationJson = await reader.ReadToEndAsync();
                if (!string.IsNullOrWhiteSpace(notificationJson))
                {
                    await HubHelpers.SendNotificationToHubAsync(notificationJson, _hubContext);
                }
            }
        }
    }
}