95 lines
3.8 KiB
C#
95 lines
3.8 KiB
C#
namespace WpywMail.Native;
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/// <summary>
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/// 发件队列。轮询待发任务 → 读取原始报文 →（可选）DKIM 签名 → 投递 → 记录结果。
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///
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/// 相比 v1 的改进：
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/// 1. 重试策略可配置（4xx 与 5xx 分开处理，指数退避带上限）；
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/// 2. DKIM 在投递时签名，因此每次重试都会带上新的时间戳；
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/// 3. 彻底失败时给发件人投递一封退信（NDR），不再静默丢失。
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/// </summary>
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public sealed class DeliveryQueue
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{
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private readonly AppConfig config;
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private readonly IMailStore store;
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private readonly DirectSmtpDelivery delivery;
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private readonly DkimSigner? signer;
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public DeliveryQueue(AppConfig config, IMailStore store, DkimSigner? signer)
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{
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this.config = config;
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this.store = store;
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this.signer = signer;
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delivery = new DirectSmtpDelivery(config, store);
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}
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public async Task RunAsync(CancellationToken token)
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{
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AppLog.Info($"[发送] 投递模式：{(config.DeliveryMode.Equals("relay", StringComparison.OrdinalIgnoreCase) ? "SMTP 中继" : "按 MX 直接投递")}");
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AppLog.Info($"[发送] 重试策略：最多 {config.Retry.MaxAttempts} 次，初始间隔 {config.Retry.InitialDelaySeconds}s，上限 {config.Retry.MaxDelaySeconds}s" +
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(config.Retry.RetryOnPermanentFailure ? $"，5xx 也重试 {config.Retry.MaxAttemptsForPermanent} 次" : "，5xx 视为永久失败"));
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while (!token.IsCancellationRequested)
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{
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foreach (var job in store.TakeDueQueue(10))
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{
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if (token.IsCancellationRequested) break;
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await ProcessAsync(job, token);
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}
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try { await Task.Delay(TimeSpan.FromSeconds(5), token); }
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catch (OperationCanceledException) { break; }
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}
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}
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private async Task ProcessAsync(QueueItem job, CancellationToken token)
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{
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var targets = string.Join(", ", job.Recipients);
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try
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{
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var message = store.GetById(job.MessageId) ?? throw new InvalidOperationException("发送队列中的邮件不存在。");
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// 每次投递都重新读取原始报文。
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// 关键顺序：先把行尾规范化为 CRLF，再签名 —— 这样签名覆盖的字节
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// 与传输时写出的字节完全一致（传输阶段只做 dot-stuffing）。
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var raw = SmtpDataEncoder.Normalize(store.ReadRaw(message.RawPath));
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if (signer is not null)
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{
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raw = signer.Sign(raw);
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message.DkimSigned = true;
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}
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await delivery.DeliverAsync(message, job.Recipients, raw, token);
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store.CompleteQueue(job);
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AppLog.Info($"[发送] 投递成功：{targets}（第 {job.Attempts + 1} 次尝试）");
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}
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catch (Exception ex)
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{
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store.FailQueue(job, ex, config.Retry, out var gaveUp);
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if (gaveUp)
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{
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AppLog.Error($"[发送] 已放弃投递：{targets} —— {ex.Message}");
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if (config.Retry.SendBounceNotification) SendBounce(job, ex);
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}
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else
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{
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AppLog.Warn($"[发送] 投递失败（将重试）：{targets} —— {ex.Message}");
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}
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}
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}
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private void SendBounce(QueueItem job, Exception error)
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{
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try
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{
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var message = store.GetById(job.MessageId);
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if (message is null) return;
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store.CreateBounce(job.OwnerEmail, message.Subject, job.Recipients, error.Message, message.RawPath);
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AppLog.Info($"[发送] 已向 {job.OwnerEmail} 投递退信通知。");
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}
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catch (Exception ex)
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{
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AppLog.Error($"[发送] 生成退信失败：{ex.Message}");
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}
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}
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}
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