WebSniffer.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Waher.Content;
using Waher.Content.Xml;
using Waher.Events;
using Waher.Networking;
using Waher.Networking.HTTP;
using Waher.Networking.Sniffers;
using Waher.Networking.Sniffers.Model;
using Waher.Runtime.Cache;
using Waher.Security;
 
namespace Waher.IoTGateway.WebResources
{
    public class WebSniffer : SnifferBase, IDisposable
    {
        private readonly BinaryPresentationMethod binaryPresentationMethod;
        private readonly DateTime created = DateTime.UtcNow;
        private readonly DateTime expires;
        private readonly ICommunicationLayer comLayer;
        private readonly string[] privileges;
        private readonly string userVariable;
        private readonly string resource;
        private readonly string snifferId;
        private readonly bool feedbackCheck;
        private string[] tabIds = null;
        private DateTime tabIdTimestamp = DateTime.MinValue;
        private Cache<string, bool> outgoing;
 
        public WebSniffer(string SnifferId, string PageResource, TimeSpan MaxLife, BinaryPresentationMethod BinaryPresentationMethod, ICommunicationLayer ComLayer,
            string UserVariable, params string[] Privileges)
            : base("Web Sniffer: " + PageResource)
        {
            this.expires = DateTime.UtcNow.Add(MaxLife);
            this.comLayer = ComLayer;
            this.snifferId = SnifferId;
            this.resource = PageResource;
            this.binaryPresentationMethod = BinaryPresentationMethod;
            this.tabIds = null;
            this.userVariable = UserVariable;
            this.privileges = Privileges;
            this.feedbackCheck = ComLayer is HttpServer;
 
            if (this.feedbackCheck)
                this.outgoing = new Cache<string, bool>(int.MaxValue, TimeSpan.FromMinutes(1), TimeSpan.FromMinutes(1), true);
            else
                this.outgoing = null;
        }
 
        public override Task DisposeAsync()
        {
            this.outgoing?.Dispose();
            this.outgoing = null;
 
            return base.DisposeAsync();
        }
 
        public string SnifferId => this.snifferId;
 
        public override BinaryPresentationMethod BinaryPresentationMethod => this.binaryPresentationMethod;
 
        private Task Process(DateTime Timestamp, string Message, string Function)
        {
            if (Timestamp >= this.expires)
                return this.Close();
            else
                return this.Push(Timestamp, Message, Function, true);
        }
 
        private async Task Push(DateTime Timestamp, string Message, string Function, bool CloseIfNoTabs)
        {
            try
            {
                DateTime Now = DateTime.UtcNow;
 
                if ((Now - this.tabIdTimestamp).TotalSeconds > 2 || this.tabIds is null || this.tabIds.Length == 0)
                {
                    this.tabIds = ClientEvents.GetTabIDsForLocation(this.resource, true, "SnifferId", this.snifferId);
                    this.tabIdTimestamp = Now;
                }
 
                if (this.feedbackCheck && Message.StartsWith('{') && Message.EndsWith('}'))
                {
                    try
                    {
                        object Parsed = JSON.Parse(Message);
                        if (Parsed is IDictionary<string, object> Obj &&
                            Obj.TryGetValue("data", out object Temp) &&
                            Temp is IDictionary<string, object> Obj2 &&
                            Obj2.TryGetValue("timestamp", out object Timestamp2) &&
                            Obj2.TryGetValue("message", out object Message2) &&
                            (this.outgoing?.ContainsKey(this.ToJson(Timestamp2, Message2)) ?? true))
                        {
                            return;
                        }
                    }
                    catch (Exception)
                    {
                        // Ignore
                    }
                }
 
                string Data = this.ToJson(XML.Encode(Timestamp), Message);
 
                this.outgoing?.Add(Data, true);
 
                int Tabs = await ClientEvents.PushEvent(this.tabIds, Function, Data, true, this.userVariable, this.privileges);
 
                if (CloseIfNoTabs && Tabs <= 0 && (Now - this.created).TotalSeconds >= 5)
                    await this.Close();
            }
            catch (Exception ex)
            {
                Log.Exception(ex);
            }
        }
 
        private string ToJson(object Timestamp, object Message)
        {
            return JSON.Encode(new KeyValuePair<string, object>[]
            {
                new KeyValuePair<string, object>("timestamp", Timestamp),
                new KeyValuePair<string, object>("message", Message)
            }, false);
        }
 
        private async Task Close()
        {
            await this.Push(DateTime.UtcNow, "Sniffer closed.", "Information", false);
            this.comLayer.Remove(this);
            await this.DisposeAsync();
        }
 
        private Task Process(DateTime Timestamp, byte[] Data, int Offset, int Count, string Function)
        {
            if (Timestamp >= this.expires)
                return this.Close();
            else
                return this.Push(Timestamp, this.HexOutput(Data, Offset, Count), Function, true);
        }
 
        private string HexOutput(byte[] Data, int Offset, int Count)
        {
            if (Data is null)
                return "<" + Count.ToString() + " bytes>";
 
            switch (Data is null ? BinaryPresentationMethod.ByteCount : this.binaryPresentationMethod)
            {
                case BinaryPresentationMethod.Hexadecimal:
                    StringBuilder sb = new StringBuilder();
                    int i = 0;
                    bool First = true;
                    byte b;
 
                    while (Count-- > 0)
                    {
                        b = Data[Offset++];
 
                        if (i > 0)
                            sb.Append(' ');
                        else if (First)
                            First = false;
                        else
                            sb.AppendLine();
 
                        sb.Append(b.ToString("X2"));
 
                        i = (i + 1) & 31;
                    }
 
                    return sb.ToString();
 
                case BinaryPresentationMethod.Base64:
                    return Convert.ToBase64String(Data);
 
                case BinaryPresentationMethod.ByteCount:
                default:
                    return "<" + Count.ToString() + " bytes>";
            }
        }
 
        public override Task Process(SnifferError Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Text, "Error");
        }
 
        public override Task Process(SnifferException Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Text, "Exception");
        }
 
        public override Task Process(SnifferInformation Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Text, "Information");
        }
 
        public override Task Process(SnifferRxBinary Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Data, Event.Offset, Event.Count, "Rx");
        }
 
        public override Task Process(SnifferRxText Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Text, "Rx");
        }
 
        public override Task Process(SnifferTxBinary Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Data, Event.Offset, Event.Count, "Tx");
        }
 
        public override Task Process(SnifferTxText Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Text, "Tx");
        }
 
        public override Task Process(SnifferWarning Event, CancellationToken Cancel)
        {
            return this.Process(Event.Timestamp, Event.Text, "Warning");
        }
 
    }
}