111 lines
3.7 KiB
C#
111 lines
3.7 KiB
C#
// Copyright (c) .NET Foundation and contributors. All rights reserved.
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// Licensed under the MIT license. See LICENSE file in the project root for full license information.
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using System;
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using Microsoft.DotNet.ProjectModel.Server.Models;
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using Microsoft.Extensions.Logging;
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using Newtonsoft.Json.Linq;
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namespace Microsoft.DotNet.ProjectModel.Server
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{
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internal class ProtocolManager
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{
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/// <summary>
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/// Environment variable for overriding protocol.
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/// </summary>
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public const string EnvDthProtocol = "DTH_PROTOCOL";
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private readonly ILogger _log;
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public ProtocolManager(int maxVersion, ILoggerFactory loggerFactory)
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{
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MaxVersion = maxVersion;
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_log = loggerFactory.CreateLogger<ProtocolManager>();
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// initialized to the highest supported version or environment overridden value
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int? protocol = GetProtocolVersionFromEnvironment();
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if (protocol.HasValue)
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{
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CurrentVersion = protocol.Value;
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EnvironmentOverridden = true;
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}
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else
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{
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CurrentVersion = 4;
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}
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}
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public int MaxVersion { get; }
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public int CurrentVersion { get; private set; }
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public bool EnvironmentOverridden { get; }
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public bool IsProtocolNegotiation(Message message)
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{
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return message?.MessageType == MessageTypes.ProtocolVersion;
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}
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public void Negotiate(Message message)
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{
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if (!IsProtocolNegotiation(message))
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{
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return;
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}
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_log.LogInformation("Initializing the protocol negotiation.");
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if (EnvironmentOverridden)
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{
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_log.LogInformation($"DTH protocol negotiation is override by environment variable {EnvDthProtocol} and set to {CurrentVersion}.");
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return;
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}
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var tokenValue = message.Payload?["Version"];
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if (tokenValue == null)
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{
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_log.LogInformation("Protocol negotiation failed. Version property is missing in payload.");
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return;
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}
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var preferredVersion = tokenValue.ToObject<int>();
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if (preferredVersion == 0)
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{
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// the preferred version can't be zero. either property is missing or the the payload is corrupted.
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_log.LogInformation("Protocol negotiation failed. Protocol version 0 is invalid.");
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return;
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}
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CurrentVersion = Math.Min(preferredVersion, MaxVersion);
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_log.LogInformation($"Protocol negotiation successed. Use protocol {CurrentVersion}");
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if (message.Sender != null)
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{
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_log.LogInformation("Respond to protocol negotiation.");
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message.Sender.Transmit(Message.FromPayload(
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MessageTypes.ProtocolVersion,
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0,
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new { Version = CurrentVersion }));
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}
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else
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{
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_log.LogInformation($"{nameof(Message.Sender)} is null.");
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}
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}
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private static int? GetProtocolVersionFromEnvironment()
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{
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// look for the environment variable DTH_PROTOCOL, if it is set override the protocol version.
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// this is for debugging.
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var strProtocol = Environment.GetEnvironmentVariable(EnvDthProtocol);
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int intProtocol = -1;
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if (!string.IsNullOrEmpty(strProtocol) && Int32.TryParse(strProtocol, out intProtocol))
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{
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return intProtocol;
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}
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return null;
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}
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}
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}
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