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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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61
FastGithub.DomainResolve/DomainResolver.cs
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@ -27,10 +27,9 @@ namespace FastGithub.DomainResolve
private readonly DnscryptProxy dnscryptProxy; private readonly DnscryptProxy dnscryptProxy;
private readonly ILogger<DomainResolver> logger; private readonly ILogger<DomainResolver> logger;
private readonly TimeSpan lookupTimeout = TimeSpan.FromSeconds(5d);
private readonly TimeSpan connectTimeout = TimeSpan.FromSeconds(5d); private readonly TimeSpan connectTimeout = TimeSpan.FromSeconds(5d);
private readonly TimeSpan dnscryptExpiration = TimeSpan.FromMinutes(5d); private readonly TimeSpan dnscryptExpiration = TimeSpan.FromMinutes(10d);
private readonly TimeSpan fallbackExpiration = TimeSpan.FromMinutes(1d); private readonly TimeSpan fallbackExpiration = TimeSpan.FromMinutes(2d);
private readonly TimeSpan loopbackExpiration = TimeSpan.FromSeconds(5d); private readonly TimeSpan loopbackExpiration = TimeSpan.FromSeconds(5d);
private readonly ConcurrentDictionary<DnsEndPoint, SemaphoreSlim> semaphoreSlims = new(); private readonly ConcurrentDictionary<DnsEndPoint, SemaphoreSlim> semaphoreSlims = new();
@ -81,7 +80,16 @@ namespace FastGithub.DomainResolve
try try
{ {
await semaphore.WaitAsync(); 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($"当前解析不到{domain.Host}可用的ip，请刷新重试");
} }
finally finally
{ {
@ -91,12 +99,11 @@ namespace FastGithub.DomainResolve
/// <summary> /// <summary>
/// 解析域名 /// 解析域名
/// 不使用缓存
/// </summary> /// </summary>
/// <param name="domain"></param> /// <param name="domain"></param>
/// <param name="cancellationToken"></param> /// <param name="cancellationToken"></param>
/// <returns></returns> /// <returns></returns>
private async Task<IPAddress> ResolveNoCacheAsync(DnsEndPoint domain, CancellationToken cancellationToken) private async Task<IPAddress?> ResolveCoreAsync(DnsEndPoint domain, CancellationToken cancellationToken)
{ {
if (this.domainResolveCache.TryGetValue<IPAddress>(domain, out var address)) if (this.domainResolveCache.TryGetValue<IPAddress>(domain, out var address))
{ {
@ -112,12 +119,12 @@ namespace FastGithub.DomainResolve
if (address == null) if (address == null)
{ {
expiration = this.fallbackExpiration; expiration = this.fallbackExpiration;
address = await this.FallbackLookupAsync(domain, cancellationToken); address = await this.LookupByFallbackAsync(domain, cancellationToken);
} }
if (address == null) if (address == null)
{ {
throw new FastGithubException($"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 // 往往是被污染的dns
@ -137,7 +144,7 @@ namespace FastGithub.DomainResolve
/// <param name="domain"></param> /// <param name="domain"></param>
/// <param name="cancellationToken"></param> /// <param name="cancellationToken"></param>
/// <returns></returns> /// <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) foreach (var dns in this.fastGithubConfig.FallbackDns)
{ {
@ -151,7 +158,7 @@ namespace FastGithub.DomainResolve
} }
/// <summary> /// <summary>
/// 查找ip /// 查找最快的可用ip
/// </summary> /// </summary>
/// <param name="dns"></param> /// <param name="dns"></param>
/// <param name="domain"></param> /// <param name="domain"></param>
@ -159,34 +166,20 @@ namespace FastGithub.DomainResolve
/// <returns></returns> /// <returns></returns>
private async Task<IPAddress?> LookupAsync(IPEndPoint dns, DnsEndPoint domain, CancellationToken cancellationToken) private async Task<IPAddress?> LookupAsync(IPEndPoint dns, DnsEndPoint domain, CancellationToken cancellationToken)
{ {
const int MAX_TRY_COUNT = 2; try
for (var i = 0; i < MAX_TRY_COUNT; i++)
{ {
try var dnsClient = new DnsClient(dns);
{ var addresses = await dnsClient.Lookup(domain.Host, RecordType.A, cancellationToken);
var dnsClient = new DnsClient(dns); addresses = addresses.Where(address => this.disableIPAddressCache.TryGetValue(address, out _) == false).ToList();
using var timeoutTokenSource = new CancellationTokenSource(this.lookupTimeout); return await this.FindFastValueAsync(addresses, domain.Port, cancellationToken);
using var linkedTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutTokenSource.Token); }
var addresses = await dnsClient.Lookup(domain.Host, RecordType.A, linkedTokenSource.Token); catch (Exception ex)
addresses = addresses.Where(address => this.disableIPAddressCache.TryGetValue(address, out _) == false).ToList(); {
return await this.FindFastValueAsync(addresses, domain.Port, cancellationToken); this.logger.LogWarning($"dns({dns})无法解析{domain.Host}：{ex.Message}");
} return default;
catch (OperationCanceledException)
{
continue;
}
catch (Exception ex)
{
this.logger.LogWarning($"dns({dns})无法解析{domain.Host}：{ex.Message}");
return default;
}
} }
this.logger.LogWarning($"dns({dns})无法解析{domain.Host}");
return default;
} }
/// <summary> /// <summary>
/// 获取最快的ip /// 获取最快的ip
/// </summary> /// </summary>