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提高域名解析成功率

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This commit is contained in:
陈国伟 2021-08-30 09:16:37 +08:00
parent 1b9e125010
commit e5e60ddb9f
1 changed files with 27 additions and 34 deletions
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43
FastGithub.DomainResolve/DomainResolver.cs
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@ -27,10 +27,9 @@ namespace FastGithub.DomainResolve
private readonly DnscryptProxy dnscryptProxy;
private readonly ILogger<DomainResolver> logger;
private readonly TimeSpan lookupTimeout = TimeSpan.FromSeconds(5d);
private readonly TimeSpan connectTimeout = TimeSpan.FromSeconds(5d);
private readonly TimeSpan dnscryptExpiration = TimeSpan.FromMinutes(5d);
private readonly TimeSpan fallbackExpiration = TimeSpan.FromMinutes(1d);
private readonly TimeSpan dnscryptExpiration = TimeSpan.FromMinutes(10d);
private readonly TimeSpan fallbackExpiration = TimeSpan.FromMinutes(2d);
private readonly TimeSpan loopbackExpiration = TimeSpan.FromSeconds(5d);
private readonly ConcurrentDictionary<DnsEndPoint, SemaphoreSlim> semaphoreSlims = new();
@ -81,7 +80,16 @@ namespace FastGithub.DomainResolve
try
{
await semaphore.WaitAsync();
return await this.ResolveNoCacheAsync(domain, cancellationToken);
for (var i = 0; i < 2; i++)
{
var address = await this.ResolveCoreAsync(domain, cancellationToken);
if (address != null)
{
return address;
}
}
throw new FastGithubException($"当前解析不到{domain.Host}可用的ip，请刷新重试");
}
finally
{
@ -91,12 +99,11 @@ namespace FastGithub.DomainResolve
/// <summary>
/// 解析域名
/// 不使用缓存
/// </summary>
/// <param name="domain"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
private async Task<IPAddress> ResolveNoCacheAsync(DnsEndPoint domain, CancellationToken cancellationToken)
private async Task<IPAddress?> ResolveCoreAsync(DnsEndPoint domain, CancellationToken cancellationToken)
{
if (this.domainResolveCache.TryGetValue<IPAddress>(domain, out var address))
{
@ -112,12 +119,12 @@ namespace FastGithub.DomainResolve
if (address == null)
{
expiration = this.fallbackExpiration;
address = await this.FallbackLookupAsync(domain, cancellationToken);
address = await this.LookupByFallbackAsync(domain, cancellationToken);
}
if (address == null)
{
throw new FastGithubException($"当前解析不到{domain.Host}可用的ip，请刷新重试");
return default;
}
// 往往是被污染的dns
@ -137,7 +144,7 @@ namespace FastGithub.DomainResolve
/// <param name="domain"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
private async Task<IPAddress?> FallbackLookupAsync(DnsEndPoint domain, CancellationToken cancellationToken)
private async Task<IPAddress?> LookupByFallbackAsync(DnsEndPoint domain, CancellationToken cancellationToken)
{
foreach (var dns in this.fastGithubConfig.FallbackDns)
{
@ -151,30 +158,21 @@ namespace FastGithub.DomainResolve
}
/// <summary>
/// 查找ip
/// 查找最快的可用ip
/// </summary>
/// <param name="dns"></param>
/// <param name="domain"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
private async Task<IPAddress?> LookupAsync(IPEndPoint dns, DnsEndPoint domain, CancellationToken cancellationToken)
{
const int MAX_TRY_COUNT = 2;
for (var i = 0; i < MAX_TRY_COUNT; i++)
{
try
{
var dnsClient = new DnsClient(dns);
using var timeoutTokenSource = new CancellationTokenSource(this.lookupTimeout);
using var linkedTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutTokenSource.Token);
var addresses = await dnsClient.Lookup(domain.Host, RecordType.A, linkedTokenSource.Token);
var addresses = await dnsClient.Lookup(domain.Host, RecordType.A, cancellationToken);
addresses = addresses.Where(address => this.disableIPAddressCache.TryGetValue(address, out _) == false).ToList();
return await this.FindFastValueAsync(addresses, domain.Port, cancellationToken);
}
catch (OperationCanceledException)
{
continue;
}
catch (Exception ex)
{
this.logger.LogWarning($"dns({dns})无法解析{domain.Host}：{ex.Message}");
@ -182,11 +180,6 @@ namespace FastGithub.DomainResolve
}
}
this.logger.LogWarning($"dns({dns})无法解析{domain.Host}");
return default;
}
/// <summary>
/// 获取最快的ip
/// </summary>