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/*
* Copyright (c) 2022 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Net.Messaging.FBM
* File: FBMRequestMessage.cs
*
* FBMRequestMessage.cs is part of VNLib.Net.Messaging.FBM which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Net.Messaging.FBM is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Net.Messaging.FBM is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System;
using System.Text;
using System.Buffers;
using System.Text.Json;
using System.Collections.Generic;
using VNLib.Utils;
using VNLib.Utils.IO;
using VNLib.Utils.Memory;
using VNLib.Utils.Extensions;
using VNLib.Utils.Memory.Caching;
namespace VNLib.Net.Messaging.FBM.Server
{
/// <summary>
/// Represents a client request message to be serviced
/// </summary>
public sealed class FBMRequestMessage : IReusable
{
private readonly List<KeyValuePair<HeaderCommand, ReadOnlyMemory<char>>> _headers;
private readonly int HeaderCharBufferSize;
/// <summary>
/// Creates a new resusable <see cref="FBMRequestMessage"/>
/// </summary>
/// <param name="headerBufferSize">The size of the buffer to alloc during initialization</param>
internal FBMRequestMessage(int headerBufferSize)
{
HeaderCharBufferSize = headerBufferSize;
_headers = new();
}
private char[]? _headerBuffer;
/// <summary>
/// The ID of the current message
/// </summary>
public int MessageId { get; private set; }
/// <summary>
/// Gets the underlying socket-id fot the current connection
/// </summary>
public string? ConnectionId { get; private set; }
/// <summary>
/// The raw request message, positioned to the body section of the message data
/// </summary>
public VnMemoryStream? RequestBody { get; private set; }
/// <summary>
/// A collection of headers for the current request
/// </summary>
public IReadOnlyList<KeyValuePair<HeaderCommand, ReadOnlyMemory<char>>> Headers => _headers;
/// <summary>
/// Status flags set during the message parsing
/// </summary>
public HeaderParseError ParseStatus { get; private set; }
/// <summary>
/// The message body data as a <see cref="ReadOnlySpan{T}"/>
/// </summary>
public ReadOnlySpan<byte> BodyData => Helpers.GetRemainingData(RequestBody!);
/// <summary>
/// Determines if the current message is considered a control frame
/// </summary>
public bool IsControlFrame { get; private set; }
/// <summary>
/// Prepares the request to be serviced
/// </summary>
/// <param name="vms">The request data packet</param>
/// <param name="socketId">The unique id of the connection</param>
/// <param name="dataEncoding">The data encoding used to decode header values</param>
internal void Prepare(VnMemoryStream vms, string socketId, Encoding dataEncoding)
{
//Store request body
RequestBody = vms;
//Store message id
MessageId = Helpers.GetMessageId(Helpers.ReadLine(vms));
//Check mid for control frame
if(MessageId == Helpers.CONTROL_FRAME_MID)
{
IsControlFrame = true;
}
else if (MessageId < 1)
{
ParseStatus |= HeaderParseError.InvalidId;
return;
}
ConnectionId = socketId;
//sliding window over remaining data from internal buffer
ForwardOnlyMemoryWriter<char> writer = new(_headerBuffer);
//Accumulate headers
while (true)
{
//Read the next line from the current stream
ReadOnlySpan<byte> line = Helpers.ReadLine(vms);
if (line.IsEmpty)
{
//Done reading headers
break;
}
HeaderCommand cmd = Helpers.GetHeaderCommand(line);
//Get header value
ERRNO charsRead = Helpers.GetHeaderValue(line, writer.Remaining.Span, dataEncoding);
if (charsRead < 0)
{
//Out of buffer space
ParseStatus |= HeaderParseError.HeaderOutOfMem;
break;
}
else if (!charsRead)
{
//Invalid header
ParseStatus |= HeaderParseError.InvalidHeaderRead;
}
else
{
//Store header as a read-only sequence
_headers.Add(new(cmd, writer.Remaining[..(int)charsRead]));
//Shift buffer window
writer.Advance(charsRead);
}
}
}
/// <summary>
/// Deserializes the request body into a new specified object type
/// </summary>
/// <typeparam name="T">The type of the object to deserialize</typeparam>
/// <param name="jso">The <see cref="JsonSerializerOptions"/> to use while deserializing data</param>
/// <returns>The deserialized object from the request body</returns>
/// <exception cref="JsonException"></exception>
public T? DeserializeBody<T>(JsonSerializerOptions? jso = default)
{
return BodyData.IsEmpty ? default : BodyData.AsJsonObject<T>(jso);
}
/// <summary>
/// Gets a <see cref="JsonDocument"/> of the request body
/// </summary>
/// <returns>The parsed <see cref="JsonDocument"/> if parsed successfully, or null otherwise</returns>
/// <exception cref="JsonException"></exception>
public JsonDocument? GetBodyAsJson()
{
Utf8JsonReader reader = new(BodyData);
return JsonDocument.TryParseValue(ref reader, out JsonDocument? jdoc) ? jdoc : default;
}
void IReusable.Prepare()
{
ParseStatus = HeaderParseError.None;
//Alloc header buffer
_headerBuffer = ArrayPool<char>.Shared.Rent(HeaderCharBufferSize);
}
bool IReusable.Release()
{
//Dispose the request message
RequestBody?.Dispose();
RequestBody = null;
//Clear headers before freeing buffer
_headers.Clear();
//Free header-buffer
ArrayPool<char>.Shared.Return(_headerBuffer!);
_headerBuffer = null;
ConnectionId = null;
MessageId = 0;
IsControlFrame = false;
return true;
}
}
}
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