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异步接收

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This commit is contained in:
陈国伟 2021-09-15 13:28:57 +08:00
parent d87292dc38
commit c252b205b1
1 changed files with 44 additions and 12 deletions
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56
FastGithub.Dns/DnsInterceptor.cs
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@ -10,6 +10,7 @@ using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Threading;
using WinDivertSharp;
using WinDivertSharp.WinAPI;
namespace FastGithub.Dns
{
@ -19,7 +20,8 @@ namespace FastGithub.Dns
[SupportedOSPlatform("windows")]
sealed class DnsInterceptor
{
const string DNS_FILTER = "udp.DstPort == 53";
private const string DNS_FILTER = "udp.DstPort == 53";
private const int ERROR_IO_PENDING = 997;
private readonly FastGithubConfig fastGithubConfig;
private readonly ILogger<DnsInterceptor> logger;
private readonly TimeSpan ttl = TimeSpan.FromSeconds(10d);
@ -47,7 +49,7 @@ namespace FastGithub.Dns
/// DNS拦截
/// </summary>
/// <param name="cancellationToken"></param>
public void Intercept(CancellationToken cancellationToken)
unsafe public void Intercept(CancellationToken cancellationToken)
{
var handle = WinDivert.WinDivertOpen(DNS_FILTER, WinDivertLayer.Network, 0, WinDivertOpenFlags.None);
if (handle == IntPtr.Zero)
@ -55,28 +57,58 @@ namespace FastGithub.Dns
return;
}
DnsFlushResolverCache();
var packetLength = 0U;
var packetBuffer = new byte[ushort.MaxValue];
using var winDivertBuffer = new WinDivertBuffer(packetBuffer);
var winDivertAddress = new WinDivertAddress();
using var ioEvent = new AutoResetEvent(false);
DnsFlushResolverCache();
while (cancellationToken.IsCancellationRequested == false)
{
if (WinDivert.WinDivertRecv(handle, winDivertBuffer, ref winDivertAddress, ref packetLength))
winDivertAddress.Reset();
var overlapped = new NativeOverlapped
{
try
EventHandle = ioEvent.SafeWaitHandle.DangerousGetHandle()
};
// false表示异步完成
if (WinDivert.WinDivertRecvEx(handle, winDivertBuffer, 0, ref winDivertAddress, ref packetLength, ref overlapped) == false)
{
var error = Marshal.GetLastWin32Error();
if (error != ERROR_IO_PENDING)
{
this.ProcessDnsPacket(packetBuffer, ref packetLength);
}
catch (Exception ex)
{
this.logger.LogWarning(ex.Message);
this.logger.LogWarning($"Unknown IO error ID {error} while awaiting overlapped result.");
continue;
}
WinDivert.WinDivertHelperCalcChecksums(winDivertBuffer, packetLength, ref winDivertAddress, WinDivertChecksumHelperParam.All);
WinDivert.WinDivertSend(handle, winDivertBuffer, packetLength, ref winDivertAddress);
while (ioEvent.WaitOne(TimeSpan.FromSeconds(1d)) == false)
{
cancellationToken.ThrowIfCancellationRequested();
}
var asyncPacketLength = 0U;
if (Kernel32.GetOverlappedResult(handle, ref overlapped, ref asyncPacketLength, false) == false)
{
this.logger.LogWarning("Failed to get overlapped result.");
continue;
}
packetLength = asyncPacketLength;
}
try
{
this.ProcessDnsPacket(packetBuffer, ref packetLength);
}
catch (Exception ex)
{
this.logger.LogWarning(ex.Message);
}
WinDivert.WinDivertHelperCalcChecksums(winDivertBuffer, packetLength, ref winDivertAddress, WinDivertChecksumHelperParam.All);
WinDivert.WinDivertSend(handle, winDivertBuffer, packetLength, ref winDivertAddress);
}
WinDivert.WinDivertClose(handle);