feat(network): pluggable connection filters; file blocklist + contribute-first CrowdSec (#2542)
Reshapes IP banning around one idea: **core owns the question, content owns every answer.**
Core gains a single accept-path seam — `IConnectionFilter` — and loses everything that used to implement one. The firewall moves to UOContent, a new file-backed blocklist joins it there, and CrowdSec is repositioned from an in-app enforcer to a contribute-first reporter.
## The seam
```csharp
public interface IConnectionFilter
{
string Name { get; }
void Configure();
void Start(CancellationToken token);
void Stop();
bool ShouldDeny(IPAddress address);
}
```
The accept path went from hardcoded branches to one question:
```csharp
else if (ConnectionFilters.ShouldDeny(remoteIP, out var deniedBy))
{
logger.Debug("{Address} denied by connection filter '{Filter}'", remoteIP, deniedBy);
}
```
Filters register during the Configure sweep. The registry is a plain array walked by an indexed loop — no enumerator, no closure, no allocation — and the first denial short-circuits. An interface dispatch is noise next to the `accept()` syscall, so pluggability costs nothing measurable on the path that has to survive a DDoS.
Whatever a hit implies — persisting, promoting to an OS bouncer, contributing to the ban channel — is the filter's business, not the accept path's.
A filter that throws is **unregistered and the connection fails open**. A filter that faults once faults for every subsequent connection, so leaving it registered means an exception and a log line per accept — exactly the amplification an attacker wants — and a broken filter must not be able to deny everyone either.
This deliberately does **not** reuse `EventSink.InvokeSocketConnect`: that fires later and allocates a `SocketConnectEventArgs` per connection, which is what the accept path avoids for rejected traffic.
## What ships behind it
**`firewall`** (UOContent) — the existing admin-curated set. Collapsed from `Firewall` + `AdminFirewall` + a threaded enforcer into one single-threaded store with **zero concurrency primitives**: the accept path, admin gump, TTL expiry and boot load all run on the game loop. Persists to `Configuration/firewall.json` with automatic migration from the legacy `firewall.cfg`. No behavior change for operators — same namespace, same gump, same commands.
**`blocklist`** (UOContent) — new. Holds a millions-strong list in-app and **demand-pages** hits up to CrowdSec, which promotes them to the OS firewall.
The motivation is concrete: CrowdSec's Windows bouncer cannot load the ~3.9M IPs that 91 community feeds produce, but it handles ~100k fine. So the millions live in-process behind a binary search, and only addresses that *actually connect* get promoted. A `PromotedGuard` suppresses re-reporting an address until the bouncer picks it up.
The list is parsed straight from UTF-8 file bytes with no per-line string allocation, off the game loop, and published as an immutable snapshot swapped through a single `volatile` reference. Reloads yield to world saves.
**`tools/Export-IpBlocklist.ps1`** — the producer. Requires PowerShell 7 and runs on Windows, Linux and macOS; Windows PowerShell 5.1 is refused up front via `#requires`. Merges a thin, non-overlapping feed set into one de-duplicated, bogon-filtered file. Parsing runs in a compiled `Add-Type` hot loop (~1s for ~4M lines instead of minutes). Written to a `.tmp` sibling and swapped with `File.Replace`, so the shard never reads a half-written list, and a total feed outage refuses to overwrite a good list with an empty one. Re-running is idempotent — it exits without downloading anything while the list on disk is younger than `-MinInterval` (default 2h, the anchor feed's own refresh period), so a misconfigured scheduler can't hammer upstream.
## CrowdSec: contribute-first
`IBanReporter` + `BanChannel` fan locally-decided bans out to external systems. `CrowdSecReporter` (UOContent) posts to LAPI `POST /v1/alerts` and retracts via `DELETE /v1/decisions`.
Reporting is **enqueue-only** on the accept path: a bounded, coalescing channel drained off-loop with bounded retry, counted drops on overflow, and a flush on shutdown. Under a DDoS the accept path never does synchronous or lock-contending per-IP work.
### Why not pull decisions from CrowdSec?
The original design streamed decisions into an in-app snapshot and enforced them at the accept gate. That's the wrong layer: by the time the shard sees the connection, the TCP handshake and socket setup are already paid for. `cs-firewall-bouncer` drops the same traffic **at the kernel**, and it's what CrowdSec is built to do. So the shard now contributes what it uniquely knows (rate-limit trips, blocklist hits from real connection attempts) and lets the OS enforce.
The one thing the OS can't do — hold millions of entries on Windows — is exactly what the in-app blocklist covers, and it feeds the same pipeline.
## Threading policy
`CLAUDE.md` rule #3 is rewritten as an explicit three-part policy, with rule #10 restated in tandem:
- Anything touching game state runs **only** on the main loop.
- Heavy work that *needs* game state must be **chunked** across ticks, never threaded.
- Heavy work that does *not* need game state (large-file parse, external I/O) **must** run off-loop **and must yield to world saves**.
Results come back via an immutable snapshot swapped through a single `volatile` reference, or `Core.LoopContext.Post` — never by letting the scheduler decide where heavy work runs. Both new subsystems follow it.
## Shared primitives
`SortedRangeIndex<T> where T : IBinaryInteger<T>` — coalesced disjoint interval arrays plus a binary search. The firewall, the blocklist, and (as of this PR) core's reserved-network tables all use it.
Coalescing is a correctness requirement, not an optimization: multi-feed lists nest CIDRs (`/24` containing a `/32`), and a search that inspects only the rightmost run whose minimum is ≤ the value is sound **only** over disjoint runs. That bug was caught in review and is covered by regression tests.
`IPAddressUtility` collects the allocation-free `IPAddress` ↔ `UInt128` conversions and CIDR parsing that were previously scattered or duplicated.
## Config
| File | Owner | Keys |
|---|---|---|
| `Configuration/bans.json` | core | `reportRateLimitTrips`, `autoBanDuration` |
| `Configuration/blocklist.json` | content | `file`, `reloadInterval`, `reportHits`, `banDuration`, `promoteSuppression` |
| `Configuration/crowdsec.json` | content | `lapiUrl`, `machineId`, `password`, `origin`, `manualBanDuration`, `flushInterval`, `maxQueue` |
| `Configuration/firewall.json` | content | persisted firewall entries (migrated from `firewall.cfg`) |
Everything is inert by default. CrowdSec self-disables without credentials; the blocklist self-disables until its file exists. A shard that changes nothing sees no behavior change.
## Notes for review
- **Core no longer references `Firewall` or `IFirewallEntry` anywhere.** `NetworkUtilities` used to build its reserved-network tables out of `CidrFirewallEntry`, which coupled core to the firewall for something unrelated to banning; those are now a `SortedRangeIndex<UInt128>`, same semantics and public API.
- **`BanChannel.Stop()` no longer persists the firewall** — a contribution coordinator has no business saving an enforcement store. That's the firewall filter's `Stop()`.
- **A dead `whitelisted` parameter was dropped** from the blocklist gate: it was hardcoded `false` at its only call site, and no whitelist concept exists in core.
- **The blocklist filter is an instance, not a static.** The static version forced its tests onto the sequential collection with a reset hook; they now run in parallel.
- `dev-docs/networking-packets.md` documents the seam for content authors, plus a known wart in the `IPAddress` ↔ `UInt128` normalization flagged for a follow-up PR.
- The generator was verified on Linux, macOS and Windows under a temporary CI matrix (since removed). It caught two portability bugs — a Windows-only path separator, and a culture-sensitive duration parse that read `2.5` as `25` on comma-decimal locales and *silently* turned a 2.5h cooldown into 25h — plus a third that made the script unparseable on Windows PowerShell 5.1. The source is ASCII-only for that last reason: `#requires` is only honored once a file parses, so non-ASCII in a BOM-less script produces parse errors instead of the version message.
## Tests
**1344 pass** (782 `Server.Tests`, 562 `UOContent.Tests`). New coverage: filter registry (registration, short-circuit, fault-disable), blocklist parsing/CIDR/coalescing, snapshot reload markers, promote-guard TTL, ban-channel fan-out, CrowdSec alert building/dedup/flush-on-stop, and the generator's output-format contract pinned against the reader.
This commit is contained in:
Kamron Batman
GitHub
parent
bec4cfa910
commit
c39454137e
52 changed files with 4655 additions and 547 deletions
65
Projects/UOContent/Misc/CrowdSec/CrowdSecAlert.cs
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65
Projects/UOContent/Misc/CrowdSec/CrowdSecAlert.cs
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@ -0,0 +1,65 @@
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/*************************************************************************
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||||
* ModernUO *
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* Copyright 2019-2026 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: CrowdSecAlert.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System.Text.Json.Serialization;
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namespace Server.Network.Bans.CrowdSec;
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/// <summary>One CrowdSec alert (<c>POST /v1/alerts</c> takes an array of these).</summary>
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public sealed class CrowdSecAlert
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{
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[JsonPropertyName("scenario")] public string Scenario { get; set; }
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[JsonPropertyName("message")] public string Message { get; set; }
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[JsonPropertyName("events_count")] public int EventsCount { get; set; } = 1;
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[JsonPropertyName("start_at")] public string StartAt { get; set; }
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[JsonPropertyName("stop_at")] public string StopAt { get; set; }
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[JsonPropertyName("capacity")] public int Capacity { get; set; }
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[JsonPropertyName("leakspeed")] public string LeakSpeed { get; set; } = "0s";
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[JsonPropertyName("simulated")] public bool Simulated { get; set; }
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[JsonPropertyName("events")] public object[] Events { get; set; } = [];
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[JsonPropertyName("remediation")] public bool Remediation { get; set; } = true;
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[JsonPropertyName("source")] public CrowdSecSource Source { get; set; }
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[JsonPropertyName("decisions")] public CrowdSecDecisionDto[] Decisions { get; set; }
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}
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public sealed class CrowdSecSource
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{
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[JsonPropertyName("scope")] public string Scope { get; set; } = "Ip";
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[JsonPropertyName("value")] public string Value { get; set; }
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}
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public sealed class CrowdSecDecisionDto
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{
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[JsonPropertyName("origin")] public string Origin { get; set; }
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[JsonPropertyName("type")] public string Type { get; set; } = "ban";
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[JsonPropertyName("scope")] public string Scope { get; set; } = "Ip";
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[JsonPropertyName("value")] public string Value { get; set; }
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[JsonPropertyName("duration")] public string Duration { get; set; }
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[JsonPropertyName("scenario")] public string Scenario { get; set; }
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}
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/// <summary>Watcher login request/response for <c>POST /v1/watchers/login</c>.</summary>
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public sealed class CrowdSecLoginRequest
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{
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[JsonPropertyName("machine_id")] public string MachineId { get; set; }
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[JsonPropertyName("password")] public string Password { get; set; }
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}
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public sealed class CrowdSecLoginResponse
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{
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[JsonPropertyName("code")] public int Code { get; set; }
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[JsonPropertyName("token")] public string Token { get; set; }
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[JsonPropertyName("expire")] public string Expire { get; set; }
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}
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137
Projects/UOContent/Misc/CrowdSec/CrowdSecAlertClient.cs
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137
Projects/UOContent/Misc/CrowdSec/CrowdSecAlertClient.cs
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@ -0,0 +1,137 @@
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/*************************************************************************
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* ModernUO *
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* Copyright 2019-2026 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: CrowdSecAlertClient.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System;
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using System.Collections.Generic;
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using System.Net;
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using System.Net.Http;
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using System.Net.Http.Headers;
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using System.Net.Http.Json;
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using System.Text.Json;
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using System.Threading;
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using System.Threading.Tasks;
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namespace Server.Network.Bans.CrowdSec;
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/// <summary>Reporter-side LAPI operations, mockable for tests.</summary>
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public interface ICrowdSecAlertClient : IDisposable
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{
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ValueTask PostAlertsAsync(IReadOnlyList<CrowdSecAlert> alerts, CancellationToken token);
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ValueTask DeleteDecisionsAsync(string origin, IPAddress ip, CancellationToken token);
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}
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/// <summary>
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/// CrowdSec LAPI watcher client: authenticates with machine credentials and posts/deletes decisions.
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/// Holds a JWT refreshed on expiry or a 401.
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/// </summary>
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public sealed class CrowdSecAlertClient : ICrowdSecAlertClient
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{
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private static readonly JsonSerializerOptions _jsonOptions = new() { PropertyNameCaseInsensitive = true };
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private readonly HttpClient _http;
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private readonly string _machineId;
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private readonly string _password;
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private string _token;
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private DateTime _tokenExpiresUtc = DateTime.MinValue;
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public CrowdSecAlertClient(CrowdSecSettings settings)
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{
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var baseUri = new Uri(settings.LapiUrl, UriKind.Absolute); // fails loud on malformed url
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_http = new HttpClient { BaseAddress = baseUri, Timeout = TimeSpan.FromSeconds(30) };
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_http.DefaultRequestHeaders.Add("User-Agent", "ModernUO-watcher/1.0");
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_machineId = settings.MachineId;
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_password = settings.Password;
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}
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private async Task EnsureAuthAsync(CancellationToken token)
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{
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if (_token != null && DateTime.UtcNow < _tokenExpiresUtc - TimeSpan.FromMinutes(1))
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{
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return;
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}
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var request = new CrowdSecLoginRequest { MachineId = _machineId, Password = _password };
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using var response = await _http.PostAsJsonAsync("/v1/watchers/login", request, _jsonOptions, token)
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.ConfigureAwait(false);
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response.EnsureSuccessStatusCode();
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var login = await response.Content.ReadFromJsonAsync<CrowdSecLoginResponse>(_jsonOptions, token)
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.ConfigureAwait(false);
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_token = login?.Token ?? throw new InvalidOperationException("CrowdSec login returned no token.");
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_tokenExpiresUtc = DateTime.TryParse(login.Expire, out var exp) ? exp.ToUniversalTime() : DateTime.UtcNow.AddHours(1);
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}
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private void Authorize(HttpRequestMessage message) =>
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message.Headers.Authorization = new AuthenticationHeaderValue("Bearer", _token);
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public async ValueTask PostAlertsAsync(IReadOnlyList<CrowdSecAlert> alerts, CancellationToken token)
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{
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if (alerts.Count == 0)
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{
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return;
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}
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await SendWithRetryAsync(() =>
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{
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var message = new HttpRequestMessage(HttpMethod.Post, "/v1/alerts")
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{
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Content = JsonContent.Create(alerts, options: _jsonOptions)
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};
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Authorize(message);
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return message;
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}, token).ConfigureAwait(false);
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}
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public async ValueTask DeleteDecisionsAsync(string origin, IPAddress ip, CancellationToken token)
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{
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var query = BuildDeleteQuery(origin, ip);
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await SendWithRetryAsync(() =>
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{
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var message = new HttpRequestMessage(HttpMethod.Delete, query);
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Authorize(message);
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return message;
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}, token).ConfigureAwait(false);
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}
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/// <summary>
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/// Builds the decisions-delete query string. <paramref name="origin"/> is operator-controlled config
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/// (crowdsec.json), so it must be escaped like any other untrusted value going into a URL.
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/// </summary>
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internal static string BuildDeleteQuery(string origin, IPAddress ip) =>
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$"/v1/decisions?origin={Uri.EscapeDataString(origin)}&ip={Uri.EscapeDataString(ip.ToString())}";
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private async ValueTask SendWithRetryAsync(Func<HttpRequestMessage> build, CancellationToken token)
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{
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await EnsureAuthAsync(token).ConfigureAwait(false);
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using var first = build();
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using var response = await _http.SendAsync(first, token).ConfigureAwait(false);
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if (response.StatusCode != HttpStatusCode.Unauthorized)
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{
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response.EnsureSuccessStatusCode();
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return;
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}
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// Token rejected mid-flight: force a re-login and retry once.
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_token = null;
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await EnsureAuthAsync(token).ConfigureAwait(false);
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using var retry = build();
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using var retryResponse = await _http.SendAsync(retry, token).ConfigureAwait(false);
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retryResponse.EnsureSuccessStatusCode();
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}
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public void Dispose() => _http.Dispose();
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}
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101
Projects/UOContent/Misc/CrowdSec/CrowdSecConfiguration.cs
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101
Projects/UOContent/Misc/CrowdSec/CrowdSecConfiguration.cs
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/*************************************************************************
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* ModernUO *
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* Copyright 2019-2026 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: CrowdSecConfiguration.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System;
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using System.IO;
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using System.Text.Json.Serialization;
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using Server.Json;
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namespace Server.Network.Bans.CrowdSec;
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/// <summary>
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/// Loads the <see cref="CrowdSecSettings"/> from <c>Configuration/crowdsec.json</c> (matching the
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/// per-feature JSON config pattern used by <c>AssistantConfiguration</c>). Loaded once; a missing file
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/// writes a disabled-by-default template so operators have something to edit.
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/// </summary>
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public static class CrowdSecConfiguration
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{
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private const string _path = "Configuration/crowdsec.json";
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public static CrowdSecSettings Settings { get; private set; }
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public static void Load()
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{
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var path = Path.Join(Core.BaseDirectory, _path);
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if (File.Exists(path))
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{
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Settings = JsonConfig.Deserialize<CrowdSecSettings>(path);
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}
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else
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{
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Settings = new CrowdSecSettings
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{
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LapiUrl = "http://127.0.0.1:8080",
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MachineId = "",
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Password = "",
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Origin = "modernuo",
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ManualBanDuration = TimeSpan.FromHours(168),
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FlushInterval = TimeSpan.FromSeconds(1),
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MaxQueue = 10000
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};
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Save();
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}
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}
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private static void Save()
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{
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JsonConfig.Serialize(Path.Join(Core.BaseDirectory, _path), Settings);
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}
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}
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/// <summary>
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/// Bound configuration for <see cref="CrowdSecReporter"/>. Read once at <c>Configure()</c>.
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/// The reporter is inert unless <see cref="ReportingEnabled"/> is true.
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/// </summary>
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public record CrowdSecSettings
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{
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/// <summary>LAPI endpoint. Default <c>http://127.0.0.1:8080</c>.</summary>
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[JsonPropertyName("lapiUrl")]
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public string LapiUrl { get; set; } = "http://127.0.0.1:8080";
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/// <summary>Watcher machine id from <c>cscli machines add</c>. Empty disables reporting.</summary>
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[JsonPropertyName("machineId")]
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public string MachineId { get; set; } = "";
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/// <summary>Watcher password paired with <see cref="MachineId"/>.</summary>
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[JsonPropertyName("password")]
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public string Password { get; set; } = "";
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/// <summary>Decision <c>origin</c> stamped on our contributions. Default <c>modernuo</c>.</summary>
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[JsonPropertyName("origin")]
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public string Origin { get; set; } = "modernuo";
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/// <summary>Duration for manual admin bans pushed to CrowdSec. Default 168h (renewable). Finite so a missed retract self-heals.</summary>
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[JsonPropertyName("manualBanDuration")]
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public TimeSpan ManualBanDuration { get; set; } = TimeSpan.FromHours(168);
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/// <summary>Max time the drain coalesces before flushing a batch. Default 1s.</summary>
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[JsonPropertyName("flushInterval")]
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public TimeSpan FlushInterval { get; set; } = TimeSpan.FromSeconds(1);
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/// <summary>Bounded contribution queue capacity; overflow is dropped (counted). Default 10000.</summary>
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[JsonPropertyName("maxQueue")]
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public int MaxQueue { get; set; } = 10000;
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[JsonIgnore]
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public bool ReportingEnabled => !string.IsNullOrWhiteSpace(MachineId) && !string.IsNullOrWhiteSpace(Password);
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}
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399
Projects/UOContent/Misc/CrowdSec/CrowdSecReporter.cs
Normal file
399
Projects/UOContent/Misc/CrowdSec/CrowdSecReporter.cs
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/*************************************************************************
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* ModernUO *
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* Copyright 2019-2026 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: CrowdSecReporter.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System;
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using System.Collections.Generic;
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using System.Net;
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using System.Threading;
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using System.Threading.Channels;
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using System.Threading.Tasks;
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using Server.Logging;
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namespace Server.Network.Bans.CrowdSec;
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/// <summary>
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/// Contributes locally-decided bans to CrowdSec via the LAPI alerts API. Non-blocking on the accept
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/// path: <see cref="Report"/> enqueues onto a bounded, drop-on-overflow channel drained by a single
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/// background task that coalesces by IP and POSTs batched alerts.
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/// </summary>
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public sealed class CrowdSecReporter : IBanReporter
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{
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private static readonly ILogger logger = LogFactory.GetLogger(typeof(CrowdSecReporter));
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internal readonly record struct ReportItem(IPAddress Ip, TimeSpan Ttl, string Reason, bool Retract);
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// Bounded retry for transient LAPI failures during a drain send (network blips, 5xx). Distinct from
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// CrowdSecAlertClient.SendWithRetryAsync's single 401-relogin retry, which is an auth concern.
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private static readonly TimeSpan[] _retryDelays = [TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(2)];
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private ICrowdSecAlertClient _client;
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private CrowdSecSettings _settings;
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private Channel<ReportItem> _queue;
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private CancellationTokenSource _cts;
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private Task _drainTask;
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private int _dropped;
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private int _sendFailures;
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public CrowdSecReporter()
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{
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}
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// Test/embedding ctor with an injected client + settings.
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internal CrowdSecReporter(ICrowdSecAlertClient client, CrowdSecSettings settings)
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{
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_client = client;
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_settings = settings;
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_queue = CreateQueue(settings.MaxQueue);
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}
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public string Name => "crowdsec";
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public bool CanRetract => true;
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public int DroppedCount => _dropped;
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/// <summary>
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/// Batches ultimately dropped after the bounded transient-retry in <see cref="DrainLoop"/> gave up.
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/// Distinct from <see cref="DroppedCount"/> (queue-overflow drops on the accept path): this counts
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/// sustained LAPI outages so operators can see contribution loss instead of it being silent.
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/// </summary>
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public int SendFailureCount => _sendFailures;
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/// <summary>The drain loop's task, so tests can assert it stays alive until the loop exits.</summary>
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internal Task DrainTaskForTesting => _drainTask;
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public static void Configure()
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{
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BanChannel.Register(new CrowdSecReporter());
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}
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public void Register()
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{
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CrowdSecConfiguration.Load();
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_settings ??= CrowdSecConfiguration.Settings;
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}
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public void Start(CancellationToken token)
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{
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if (!_settings.ReportingEnabled)
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{
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logger.Information("CrowdSec reporter disabled (machineId/password empty in crowdsec.json)");
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return;
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}
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_client ??= new CrowdSecAlertClient(_settings);
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_queue ??= CreateQueue(_settings.MaxQueue);
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_cts = CancellationTokenSource.CreateLinkedTokenSource(token);
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_drainTask = Task.Run(() => DrainLoop(_cts.Token), _cts.Token);
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}
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public void Stop()
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{
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_cts?.Cancel();
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// The flush below reads a SingleReader channel, so wait for the drain to actually exit first.
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var drainExited = true;
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try
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{
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// Wait(timeout) is false only on timeout; a throw means faulted/cancelled, which is still exited.
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drainExited = _drainTask == null || _drainTask.Wait(TimeSpan.FromSeconds(2));
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}
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catch
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{
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// Ignored: a faulted wait means the drain has completed and released the channel.
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}
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_cts?.Dispose();
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_cts = null;
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if (drainExited)
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{
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FlushRemainingOnStop();
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}
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_client?.Dispose();
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_drainTask = null;
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}
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/// <summary>
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/// Best-effort bounded flush of whatever is still queued at shutdown. Blocking is correct here — the
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/// loop has stopped ticking — but must not happen on the loop thread: <see cref="Stop"/> runs where
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/// <c>SynchronizationContext.Current</c> is the <c>EventLoopContext</c>, and a captured continuation
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/// would be posted to a queue nothing pumps any more. <see cref="Task.Run(Func{Task})"/> keeps the
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/// chain on the pool; the bounded wait caps a wedged send at a few seconds of shutdown.
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/// </summary>
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private void FlushRemainingOnStop()
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{
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if (_queue == null || _client == null)
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{
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return;
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}
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_queue.Writer.TryComplete();
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List<ReportItem> reports = [];
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List<ReportItem> retracts = [];
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while (_queue.Reader.TryRead(out var item))
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{
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(item.Retract ? retracts : reports).Add(item);
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}
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if (reports.Count == 0 && retracts.Count == 0)
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{
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return;
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}
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try
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{
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if (!Task.Run(() => FlushRemainingOnStopAsync(reports, retracts)).Wait(TimeSpan.FromSeconds(4)))
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{
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logger.Warning(
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"CrowdSec flush-on-stop timed out; {Count} item(s) not contributed",
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reports.Count + retracts.Count
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);
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}
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}
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catch (Exception e)
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{
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logger.Warning(e, "CrowdSec flush-on-stop failed");
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}
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}
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/// <summary>
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/// Uses a fresh token, not the drain loop's already-cancelled one, which would fail every send
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/// immediately. Reports go as one deduped batch; retracts go as individual DELETEs so an admin's
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/// unban propagates on a clean shutdown. Leftovers self-heal via
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/// <see cref="CrowdSecSettings.ManualBanDuration"/>.
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/// </summary>
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private async Task FlushRemainingOnStopAsync(List<ReportItem> reports, List<ReportItem> retracts)
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{
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using var flushCts = new CancellationTokenSource(TimeSpan.FromSeconds(3));
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if (reports.Count > 0)
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{
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var alerts = BuildAlerts(reports, _settings, DateTime.UtcNow);
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try
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{
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await _client.PostAlertsAsync(alerts, flushCts.Token).ConfigureAwait(false);
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}
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catch (Exception e)
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{
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logger.Warning(e, "CrowdSec flush-on-stop reports failed");
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RecordSendFailure(alerts.Count);
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}
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}
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HashSet<string> seen = [];
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for (var i = 0; i < retracts.Count; i++)
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{
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if (flushCts.IsCancellationRequested)
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{
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break; // out of budget; the rest self-heal via ManualBanDuration
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}
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var ip = retracts[i].Ip;
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if (!seen.Add(ip.ToString()))
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{
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continue;
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}
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try
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{
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await _client.DeleteDecisionsAsync(_settings.Origin, ip, flushCts.Token).ConfigureAwait(false);
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}
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catch (Exception e)
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{
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logger.Warning(e, "CrowdSec flush-on-stop retract failed for {Address}", ip);
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RecordSendFailure(1);
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}
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}
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}
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public void Report(IPAddress address, TimeSpan ttl, string reason) =>
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Enqueue(new ReportItem(address, ttl, reason, false));
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public void Retract(IPAddress address) =>
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Enqueue(new ReportItem(address, TimeSpan.Zero, "retract", true));
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private void Enqueue(ReportItem item)
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{
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if (_queue == null || !_queue.Writer.TryWrite(item))
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{
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Interlocked.Increment(ref _dropped);
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}
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}
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// FullMode.Wait (the default) makes TryWrite return false immediately when the channel is full
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// instead of blocking the caller — exactly the non-blocking drop-on-overflow behavior the accept
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// path requires. DropWrite would silently discard the new item and always report success, which
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// would make overflow undetectable.
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private static Channel<ReportItem> CreateQueue(int capacity) =>
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Channel.CreateBounded<ReportItem>(new BoundedChannelOptions(Math.Max(1, capacity))
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{
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FullMode = BoundedChannelFullMode.Wait,
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SingleReader = true
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});
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// Must return Task: Start() passes this to Task.Run, which has no Func<ValueTask> overload, so a
|
||||
// ValueTask would bind to Task.Run<TResult> and yield a Task<ValueTask> that completes at the first
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// await rather than when the loop exits.
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private async Task DrainLoop(CancellationToken token)
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{
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var reader = _queue.Reader;
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||||
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||||
while (!token.IsCancellationRequested)
|
||||
{
|
||||
try
|
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{
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||||
if (!await reader.WaitToReadAsync(token).ConfigureAwait(false))
|
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{
|
||||
return;
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}
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// Coalesce a burst before flushing.
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await Task.Delay(_settings.FlushInterval, token).ConfigureAwait(false);
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List<ReportItem> reports = [];
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List<ReportItem> retracts = [];
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while (reader.TryRead(out var item))
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{
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||||
(item.Retract ? retracts : reports).Add(item);
|
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}
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if (reports.Count > 0)
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{
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var alerts = BuildAlerts(reports, _settings, DateTime.UtcNow);
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if (!await SendWithBoundedRetryAsync(() => _client.PostAlertsAsync(alerts, token), token)
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.ConfigureAwait(false))
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{
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RecordSendFailure(alerts.Count);
|
||||
}
|
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}
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for (var i = 0; i < retracts.Count; i++)
|
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{
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var ip = retracts[i].Ip;
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if (!await SendWithBoundedRetryAsync(() => _client.DeleteDecisionsAsync(_settings.Origin, ip, token), token)
|
||||
.ConfigureAwait(false))
|
||||
{
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||||
RecordSendFailure(1);
|
||||
}
|
||||
}
|
||||
}
|
||||
catch (OperationCanceledException)
|
||||
{
|
||||
return;
|
||||
}
|
||||
catch (Exception e)
|
||||
{
|
||||
// Contribution is auxiliary: log and keep draining. Never crash the shard.
|
||||
logger.Warning(e, "CrowdSec contribution flush failed; dropped this batch");
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Sends with up to 3 attempts total (1 initial + 2 retries), backing off 1s then 2s between
|
||||
/// attempts, for transient LAPI failures (network blips, 5xx). Backoff uses <see cref="Task.Delay"/>
|
||||
/// so it never blocks the thread; a cancellation during backoff propagates as
|
||||
/// <see cref="OperationCanceledException"/> so the drain loop exits cleanly. Returns false (never
|
||||
/// throws for a send failure) once attempts are exhausted, so the caller can count the drop and keep
|
||||
/// draining instead of losing the rest of the batch/queue.
|
||||
/// </summary>
|
||||
private static async ValueTask<bool> SendWithBoundedRetryAsync(Func<ValueTask> send, CancellationToken token)
|
||||
{
|
||||
for (var attempt = 0; ; attempt++)
|
||||
{
|
||||
try
|
||||
{
|
||||
await send().ConfigureAwait(false);
|
||||
return true;
|
||||
}
|
||||
catch (OperationCanceledException)
|
||||
{
|
||||
throw;
|
||||
}
|
||||
catch (Exception e)
|
||||
{
|
||||
if (attempt >= _retryDelays.Length)
|
||||
{
|
||||
logger.Warning(e, "CrowdSec send failed after {Attempts} attempt(s); giving up", attempt + 1);
|
||||
return false;
|
||||
}
|
||||
|
||||
var delay = _retryDelays[attempt];
|
||||
logger.Warning(e, "CrowdSec send failed (attempt {Attempt}); retrying in {Delay}", attempt + 1, delay);
|
||||
await Task.Delay(delay, token).ConfigureAwait(false);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
private void RecordSendFailure(int itemCount)
|
||||
{
|
||||
var total = Interlocked.Increment(ref _sendFailures);
|
||||
logger.Warning(
|
||||
"CrowdSec contribution batch dropped after retries ({Items} item(s)); total dropped batches: {Total}",
|
||||
itemCount,
|
||||
total
|
||||
);
|
||||
}
|
||||
|
||||
/// <summary>Coalesces items by IP (last write wins) and builds one alert per unique address.</summary>
|
||||
internal static List<CrowdSecAlert> BuildAlerts(IEnumerable<ReportItem> items, CrowdSecSettings settings, DateTime nowUtc)
|
||||
{
|
||||
Dictionary<string, ReportItem> byIp = [];
|
||||
foreach (var item in items)
|
||||
{
|
||||
byIp[item.Ip.ToString()] = item;
|
||||
}
|
||||
|
||||
var timestamp = nowUtc.ToString("yyyy-MM-ddTHH:mm:ss.fffZ");
|
||||
var alerts = new List<CrowdSecAlert>(byIp.Count);
|
||||
|
||||
foreach (var (value, item) in byIp)
|
||||
{
|
||||
var ttl = item.Reason == "manual" || item.Ttl <= TimeSpan.Zero ? settings.ManualBanDuration : item.Ttl;
|
||||
var scenario = $"{settings.Origin}/{item.Reason}";
|
||||
|
||||
alerts.Add(new CrowdSecAlert
|
||||
{
|
||||
Scenario = scenario,
|
||||
Message = $"ModernUO {item.Reason} ban for {value}",
|
||||
StartAt = timestamp,
|
||||
StopAt = timestamp,
|
||||
Source = new CrowdSecSource { Scope = "Ip", Value = value },
|
||||
Decisions =
|
||||
[
|
||||
new CrowdSecDecisionDto
|
||||
{
|
||||
Origin = settings.Origin,
|
||||
Type = "ban",
|
||||
Scope = "Ip",
|
||||
Value = value,
|
||||
Duration = FormatDuration(ttl),
|
||||
Scenario = scenario
|
||||
}
|
||||
]
|
||||
});
|
||||
}
|
||||
|
||||
return alerts;
|
||||
}
|
||||
|
||||
/// <summary>CrowdSec accepts Go durations; whole seconds are unambiguous and sufficient.</summary>
|
||||
internal static string FormatDuration(TimeSpan ttl)
|
||||
{
|
||||
var seconds = (long)ttl.TotalSeconds;
|
||||
return $"{Math.Max(1, seconds)}s";
|
||||
}
|
||||
}
|
||||
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