【愚公系列】2022年11月 .NET CORE工具案例-.NET 7中的Quic通信

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发布于 2022-11-16 15:37:47

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发布于 2022-11-16 15:37:47

文章被收录于专栏：历史专栏

文章目录

前言

QUIC（Quick UDP Internet Connection）是谷歌制定的一种基于UDP的低时延的互联网传输层协议。我们知道，TCP/IP协议族是互联网的基础。其中传输层协议包括TCP和UDP协议。与TCP协议相比，UDP更为轻量，但是错误校验也要少得多。这意味着UDP往往效率更高（不经常跟服务器端通信查看数据包是否送达或者按序），但是可靠性比不上TCP。通常游戏、流媒体以及VoIP等应用均采用UDP，而网页、邮件、远程登录等大部分的应用均采用TCP。

QUIC很好地解决了当今传输层和应用层面临的各种需求，包括处理更多的连接，安全性，和低延迟。QUIC融合了包括TCP，TLS，HTTP/2等协议的特性，但基于UDP传输。QUIC的一个主要目标就是减少连接延迟，当客户端第一次连接服务器时，QUIC只需要1RTT（Round-Trip Time）的延迟就可以建立可靠安全的连接,相对于TCP+TLS的1-3次RTT要更加快捷。之后客户端可以在本地缓存加密的认证信息，再次与服务器建立连接时可以实现0-RTT的连接建立延迟。QUIC同时复用了HTTP/2协议的多路复用功能（Multiplexing），但由于QUIC基于UDP所以避免了HTTP/2的队头阻塞（Head-of-Line Blocking）问题。因为QUIC基于UDP，运行在用户域而不是系统内核，使得QUIC协议可以快速的更新和部署，从而很好地解决了TCP协议部署及更新的困难。

以下是TCP和Quic通信过程的示例图：

一、.NET 7中的Quic通信

1.下载.NET 7预览版

下载地址：https://dotnet.microsoft.com/zh-cn/download/dotnet/7.0

2.vs2022配置使用预览版SDK

3. .NET 中使用 Quic

下面是 System.Net.Quic 命名空间下，比较重要的几个类。

QuicConnection

表示一个 QUIC 连接，本身不发送也不接收数据，它可以打开或者接收多个QUIC 流。

QuicListener

用来监听入站的 Quic 连接，一个 QuicListener 可以接收多个 Quic 连接。

QuicStream

表示 Quic 流，它可以是单向的（QuicStreamType.Unidirectional），只允许创建方写入数据，也可以是双向的（QuicStreamType.Bidirectional），它允许两边都可以写入数据。

4. .NET 中使用 Quic代码解析

4.1 服务端

建了一个 QuicListener，监听了本地端口 9999，指定了 ALPN 协议版本。

// 创建 QuicListener
var listener = await QuicListener.ListenAsync(new QuicListenerOptions
{ 
    ApplicationProtocols = new List<SslApplicationProtocol> { SslApplicationProtocol.Http3  },
    ListenEndPoint = new IPEndPoint(IPAddress.Loopback,9999), 
    ConnectionOptionsCallback = (connection,ssl, token) => ValueTask.FromResult(new QuicServerConnectionOptions()
    {
        DefaultStreamErrorCode = 0,
        DefaultCloseErrorCode = 0,
        ServerAuthenticationOptions = new SslServerAuthenticationOptions()
        {
            ApplicationProtocols = new List<SslApplicationProtocol>() { SslApplicationProtocol.Http3 },
            ServerCertificate = GenerateManualCertificate()//生成证书
        }
    }) 
});

因为 Quic 需要 TLS 加密，所以要指定一个证书，GenerateManualCertificate 方法可以方便地创建一个本地的测试证书。

X509Certificate2 GenerateManualCertificate()
{
    X509Certificate2 cert = null;
    var store = new X509Store("KestrelWebTransportCertificates", StoreLocation.CurrentUser);
    store.Open(OpenFlags.ReadWrite);
    if (store.Certificates.Count > 0)
    {
        cert = store.Certificates[^1];

        // rotate key after it expires
        if (DateTime.Parse(cert.GetExpirationDateString(), null) < DateTimeOffset.UtcNow)
        {
            cert = null;
        }
    }
    if (cert == null)
    {
        // generate a new cert
        var now = DateTimeOffset.UtcNow;
        SubjectAlternativeNameBuilder sanBuilder = new();
        sanBuilder.AddDnsName("localhost");
        using var ec = ECDsa.Create(ECCurve.NamedCurves.nistP256);
        CertificateRequest req = new("CN=localhost", ec, HashAlgorithmName.SHA256);
        // Adds purpose
        req.CertificateExtensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection
        {
            new("1.3.6.1.5.5.7.3.1") // serverAuth

        }, false));
        // Adds usage
        req.CertificateExtensions.Add(new X509KeyUsageExtension(X509KeyUsageFlags.DigitalSignature, false));
        // Adds subject alternate names
        req.CertificateExtensions.Add(sanBuilder.Build());
        // Sign
        using var crt = req.CreateSelfSigned(now, now.AddDays(14)); // 14 days is the max duration of a certificate for this
        cert = new(crt.Export(X509ContentType.Pfx));

        // Save
        store.Add(cert);
    }
    store.Close();

    var hash = SHA256.HashData(cert.RawData);
    var certStr = Convert.ToBase64String(hash);
    //Console.WriteLine($"\n\n\n\n\nCertificate: {certStr}\n\n\n\n"); // <-- you will need to put this output into the JS API call to allow the connection
    return cert;
}

阻塞线程，直到接收到一个 Quic 连接，一个 QuicListener 可以接收多个连接。并接收一个入站的 Quic 流, 一个 QuicConnection 可以支持多个流。

var connection = await listener.AcceptConnectionAsync();

Console.WriteLine($"Client [{connection.RemoteEndPoint}]: connected");

var stream = await connection.AcceptInboundStreamAsync();

Console.WriteLine($"Stream [{stream.Id}]: created");

使用 System.IO.Pipeline 处理流数据，读取行数据，并回复一个 ack 消息。

await ProcessLinesAsync(stream);

// 处理流数据
async Task ProcessLinesAsync(QuicStream stream)
{
    var reader = PipeReader.Create(stream);  
    var writer = PipeWriter.Create(stream);

    while (true)
    {
        ReadResult result = await reader.ReadAsync();
        ReadOnlySequence<byte> buffer = result.Buffer;

        while (TryReadLine(ref buffer, out ReadOnlySequence<byte> line))
        {
            // Process the line. 
            ProcessLine(line);

            // Ack 
            //await writer.WriteAsync(System.Text.Encoding.UTF8.GetBytes($"ack: {DateTime.Now.ToString("HH:mm:ss")} \n"));
        }

        // Tell the PipeReader how much of the buffer has been consumed.
        reader.AdvanceTo(buffer.Start, buffer.End);

        // Stop reading if there's no more data coming.
        if (result.IsCompleted)
        {
            break;
        } 
    }

    Console.WriteLine($"Stream [{stream.Id}]: completed");

    await reader.CompleteAsync();  
    await writer.CompleteAsync();    
} 

bool TryReadLine(ref ReadOnlySequence<byte> buffer, out ReadOnlySequence<byte> line)
{
    // Look for a EOL in the buffer.
    SequencePosition? position = buffer.PositionOf((byte)'\n');

    if (position == null)
    {
        line = default;
        return false;
    }

    // Skip the line + the \n.
    line = buffer.Slice(0, position.Value);
    buffer = buffer.Slice(buffer.GetPosition(1, position.Value));
    return true;
} 

void ProcessLine(in ReadOnlySequence<byte> buffer)
{
    foreach (var segment in buffer)
    {
        Console.WriteLine("Recevied -> " + System.Text.Encoding.UTF8.GetString(segment.Span));
    }

    Console.WriteLine();
}

4.2 客户端

4.2.1 单个流

直接使用 QuicConnection.ConnectAsync 连接到服务端。

Console.WriteLine("Quic Client Running...");

await Task.Delay(3000);

// 连接到服务端
var connection = await QuicConnection.ConnectAsync(new QuicClientConnectionOptions
{
    DefaultCloseErrorCode = 0,
    DefaultStreamErrorCode = 0,
    RemoteEndPoint = new IPEndPoint(IPAddress.Loopback, 9999),
    ClientAuthenticationOptions = new SslClientAuthenticationOptions
    {
        ApplicationProtocols = new List<SslApplicationProtocol> { SslApplicationProtocol.Http3 },
        RemoteCertificateValidationCallback = (sender, certificate, chain, errors) =>
        {
            return true;
        }
    }
});

创建一个出站的双向流。

// 打开一个出站的双向流
var stream = await connection.OpenOutboundStreamAsync(QuicStreamType.Bidirectional); 

var reader = PipeReader.Create(stream);
var writer = PipeWriter.Create(stream);

后台读取流数据，然后循环写入数据。

// 后台读取流数据
_ = ProcessLinesAsync(stream);

Console.WriteLine(); 

// 写入数据
for (int i = 0; i < 7; i++)
{
    await Task.Delay(2000);

    var message = $"Hello Quic {i} \n";

    Console.Write("Send -> " + message);  

    await writer.WriteAsync(Encoding.UTF8.GetBytes(message)); 
}

await writer.CompleteAsync(); 

Console.ReadKey();

ProcessLinesAsync 和服务端一样，使用 System.IO.Pipeline 读取流数据。

async Task ProcessLinesAsync(QuicStream stream)
{
    while (true)
    {
        ReadResult result = await reader.ReadAsync();
        ReadOnlySequence<byte> buffer = result.Buffer;

        while (TryReadLine(ref buffer, out ReadOnlySequence<byte> line))
        { 
            // 处理行数据
            ProcessLine(line);
        }
     
        reader.AdvanceTo(buffer.Start, buffer.End); 
     
        if (result.IsCompleted)
        {
            break;
        }
    }

    await reader.CompleteAsync();
    await writer.CompleteAsync();

} 

bool TryReadLine(ref ReadOnlySequence<byte> buffer, out ReadOnlySequence<byte> line)
{ 
    SequencePosition? position = buffer.PositionOf((byte)'\n');

    if (position == null)
    {
        line = default;
        return false;
    }
 
    line = buffer.Slice(0, position.Value);
    buffer = buffer.Slice(buffer.GetPosition(1, position.Value));
    return true;
}

void ProcessLine(in ReadOnlySequence<byte> buffer)
{
    foreach (var segment in buffer)
    {
        Console.Write("Recevied -> " + System.Text.Encoding.UTF8.GetString(segment.Span));
        Console.WriteLine();
    }

    Console.WriteLine();
}

到这里，客户端和服务端的代码都完成了，客户端使用 Quic 流发送了一些消息给服务端，服务端收到消息后在控制台输出，并回复一个 Ack 消息，因为我们创建了一个双向流。

4.2.2 多个流

我们上面说到了一个 QuicConnection 可以创建多个流，并行传输数据。

改造一下服务端的代码，支持接收多个 Quic 流。

var cts = new CancellationTokenSource();

while (!cts.IsCancellationRequested)
{
    var stream = await connection.AcceptInboundStreamAsync();

    Console.WriteLine($"Stream [{stream.Id}]: created");

    Console.WriteLine();

    _ = ProcessLinesAsync(stream); 
} 

Console.ReadKey();

对于客户端，我们用多个线程创建多个 Quic 流，并同时发送消息。

默认情况下，一个 Quic 连接的流的限制是 100，当然你可以设置 QuicConnectionOptions 的 MaxInboundBidirectionalStreams 和 MaxInboundUnidirectionalStreams 参数。

for (int j = 0; j < 5; j++)
{
    _ = Task.Run(async () => {

        // 创建一个出站的双向流
        var stream = await connection.OpenOutboundStreamAsync(QuicStreamType.Bidirectional); 
      
        var writer = PipeWriter.Create(stream); 

        Console.WriteLine();
 
        await Task.Delay(2000);
        
        var message = $"Hello Quic [{stream.Id}] \n";

        Console.Write("Send -> " + message);

        await writer.WriteAsync(Encoding.UTF8.GetBytes(message));

        await writer.CompleteAsync(); 
    });  
}

using System;
using System.Buffers;
using System.IO.Pipelines;
using System.IO.Pipes;
using System.Net;
using System.Net.Quic;
using System.Net.Security; 
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates; 

Console.WriteLine("Quic Server Running...");

// 创建 QuicListener
var listener = await QuicListener.ListenAsync(new QuicListenerOptions
{ 
    ApplicationProtocols = new List<SslApplicationProtocol> { SslApplicationProtocol.Http3  },
    ListenEndPoint = new IPEndPoint(IPAddress.Loopback,9999), 
    ConnectionOptionsCallback = (connection,ssl, token) => ValueTask.FromResult(new QuicServerConnectionOptions()
    {
        DefaultStreamErrorCode = 0,
        DefaultCloseErrorCode = 0,
        ServerAuthenticationOptions = new SslServerAuthenticationOptions()
        {
            ApplicationProtocols = new List<SslApplicationProtocol>() { SslApplicationProtocol.Http3 },
            ServerCertificate = GenerateManualCertificate()
        }
    }) 
});
// 生成证书
X509Certificate2 GenerateManualCertificate()
{
    X509Certificate2 cert = null;
    var store = new X509Store("KestrelWebTransportCertificates", StoreLocation.CurrentUser);
    store.Open(OpenFlags.ReadWrite);
    if (store.Certificates.Count > 0)
    {
        cert = store.Certificates[^1];

        // rotate key after it expires
        if (DateTime.Parse(cert.GetExpirationDateString(), null) < DateTimeOffset.UtcNow)
        {
            cert = null;
        }
    }
    if (cert == null)
    {
        // generate a new cert
        var now = DateTimeOffset.UtcNow;
        SubjectAlternativeNameBuilder sanBuilder = new();
        sanBuilder.AddDnsName("localhost");
        using var ec = ECDsa.Create(ECCurve.NamedCurves.nistP256);
        CertificateRequest req = new("CN=localhost", ec, HashAlgorithmName.SHA256);
        // Adds purpose
        req.CertificateExtensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection
        {
            new("1.3.6.1.5.5.7.3.1") // serverAuth

        }, false));
        // Adds usage
        req.CertificateExtensions.Add(new X509KeyUsageExtension(X509KeyUsageFlags.DigitalSignature, false));
        // Adds subject alternate names
        req.CertificateExtensions.Add(sanBuilder.Build());
        // Sign
        using var crt = req.CreateSelfSigned(now, now.AddDays(14)); // 14 days is the max duration of a certificate for this
        cert = new(crt.Export(X509ContentType.Pfx));

        // Save
        store.Add(cert);
    }
    store.Close();

    var hash = SHA256.HashData(cert.RawData);
    var certStr = Convert.ToBase64String(hash);
    //Console.WriteLine($"\n\n\n\n\nCertificate: {certStr}\n\n\n\n"); // <-- you will need to put this output into the JS API call to allow the connection
    return cert;
}

var connection = await listener.AcceptConnectionAsync();

Console.WriteLine($"Client [{connection.RemoteEndPoint}]: connected");

var cts = new CancellationTokenSource();

while (!cts.IsCancellationRequested)
{
    var stream = await connection.AcceptInboundStreamAsync();

    Console.WriteLine($"Stream [{stream.Id}]: created");

    Console.WriteLine();

    _ = ProcessLinesAsync(stream); 
} 

Console.ReadKey();      

// 处理流数据
async Task ProcessLinesAsync(QuicStream stream)
{
    var reader = PipeReader.Create(stream);  
    var writer = PipeWriter.Create(stream);

    while (true)
    {
        ReadResult result = await reader.ReadAsync();
        ReadOnlySequence<byte> buffer = result.Buffer;

        while (TryReadLine(ref buffer, out ReadOnlySequence<byte> line))
        {
            // Process the line. 
            ProcessLine(line);

            // Ack 
            //await writer.WriteAsync(System.Text.Encoding.UTF8.GetBytes($"ack: {DateTime.Now.ToString("HH:mm:ss")} \n"));
        }

        // Tell the PipeReader how much of the buffer has been consumed.
        reader.AdvanceTo(buffer.Start, buffer.End);

        // Stop reading if there's no more data coming.
        if (result.IsCompleted)
        {
            break;
        } 
    }

    Console.WriteLine($"Stream [{stream.Id}]: completed");

    await reader.CompleteAsync();  
    await writer.CompleteAsync();    
} 

bool TryReadLine(ref ReadOnlySequence<byte> buffer, out ReadOnlySequence<byte> line)
{
    // Look for a EOL in the buffer.
    SequencePosition? position = buffer.PositionOf((byte)'\n');

    if (position == null)
    {
        line = default;
        return false;
    }

    // Skip the line + the \n.
    line = buffer.Slice(0, position.Value);
    buffer = buffer.Slice(buffer.GetPosition(1, position.Value));
    return true;
} 

void ProcessLine(in ReadOnlySequence<byte> buffer)
{
    foreach (var segment in buffer)
    {
        Console.WriteLine("Recevied -> " + System.Text.Encoding.UTF8.GetString(segment.Span));
    }

    Console.WriteLine();
}

完整客户端：

using System.Buffers;
using System.IO;
using System.IO.Pipelines;
using System.IO.Pipes;
using System.Net;
using System.Net.Quic;
using System.Net.Security;
using System.Reflection.PortableExecutable;
using System.Text;
using System.Xml.Linq;

Console.WriteLine("Quic Client Running...");

await Task.Delay(3000);

// 连接到服务端
var connection = await QuicConnection.ConnectAsync(new QuicClientConnectionOptions
{
    DefaultCloseErrorCode = 0,
    DefaultStreamErrorCode = 0,
    RemoteEndPoint = new IPEndPoint(IPAddress.Loopback, 9999),
    ClientAuthenticationOptions = new SslClientAuthenticationOptions
    {
        ApplicationProtocols = new List<SslApplicationProtocol> { SslApplicationProtocol.Http3 },
        RemoteCertificateValidationCallback = (sender, certificate, chain, errors) =>
        {
            return true;
        }
    }
});

for (int j = 0; j < 5; j++)
{
    _ = Task.Run(async () => {

        // 打开一个出站的双向流
        var stream = await connection.OpenOutboundStreamAsync(QuicStreamType.Bidirectional); 
      
        var writer = PipeWriter.Create(stream); 

        Console.WriteLine();

        // 写入数据
        await Task.Delay(2000);

        var message = $"Hello Quic [{stream.Id}] \n";

        Console.Write("Send -> " + message);

        await writer.WriteAsync(Encoding.UTF8.GetBytes(message));

        await writer.CompleteAsync(); 
    });  
} 


Console.ReadKey();

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原始发表：2022-11-08，如有侵权请联系 cloudcommunity@tencent.com 删除

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