feat(metrics): track per-IP domain request metrics across HTTP and TCP passthrough traffic

changelog.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 2026-04-13 - 27.6.0 - feat(metrics)
+track per-IP domain request metrics across HTTP and TCP passthrough traffic
+
+- records domain request counts per frontend IP from HTTP Host headers and TCP SNI
+- exposes per-IP domain maps and top IP-domain request pairs through the TypeScript metrics adapter
+- bounds per-IP domain tracking and prunes stale entries to limit memory growth
+- adds metrics system documentation covering architecture, collected data, and known gaps
+
 ## 2026-04-06 - 27.5.0 - feat(security)
 add domain-scoped IP allow list support across HTTP and passthrough filtering
 

readme.metrics.md

@@ -0,0 +1,484 @@
+# SmartProxy Metrics System
+
+## Architecture
+
+Two-tier design separating the data plane from the observation plane:
+
+**Hot path (per-chunk, lock-free):** All recording in the proxy data plane touches only `AtomicU64` counters. No `Mutex` is ever acquired on the forwarding path. `CountingBody` batches flushes every 64KB to reduce DashMap shard contention.
+
+**Cold path (1Hz sampling):** A background tokio task drains pending atomics into `ThroughputTracker` circular buffers (Mutex-guarded), producing per-second throughput history. Same task prunes orphaned entries and cleans up rate limiter state.
+
+**Read path (on-demand):** `snapshot()` reads all atomics and locks ThroughputTrackers to build a serializable `Metrics` struct. TypeScript polls this at 1s intervals via IPC.
+
+```
+Data Plane (lock-free)                Background (1Hz)              Read Path
+─────────────────────                 ──────────────────             ─────────
+record_bytes() ──> AtomicU64 ──┐
+record_http_request() ──> AtomicU64 ──┤
+connection_opened/closed() ──> AtomicU64 ──┤     sample_all()        snapshot()
+backend_*() ──> DashMap<AtomicU64> ──┤────> drain atomics ──────> Metrics struct
+protocol_*() ──> AtomicU64 ──┤       feed ThroughputTrackers      ──> JSON
+datagram_*() ──> AtomicU64 ──┘       prune orphans                ──> IPC stdout
+                                                                   ──> TS cache
+                                                                   ──> IMetrics API
+```
+
+### Key Types
+
+| Type | Crate | Purpose |
+|---|---|---|
+| `MetricsCollector` | `rustproxy-metrics` | Central store. All DashMaps, atomics, and throughput trackers |
+| `ThroughputTracker` | `rustproxy-metrics` | Circular buffer of 1Hz samples. Default 3600 capacity (1 hour) |
+| `ForwardMetricsCtx` | `rustproxy-passthrough` | Carries `Arc<MetricsCollector>` + route_id + source_ip through TCP forwarding |
+| `CountingBody` | `rustproxy-http` | Wraps HTTP bodies, batches byte recording per 64KB, flushes on drop |
+| `ProtocolGuard` | `rustproxy-http` | RAII guard for frontend/backend protocol active/total counters |
+| `ConnectionGuard` | `rustproxy-passthrough` | RAII guard calling `connection_closed()` on drop |
+| `RustMetricsAdapter` | TypeScript | Polls Rust via IPC, implements `IMetrics` interface over cached JSON |
+
+---
+
+## What's Collected
+
+### Global Counters
+
+| Metric | Type | Updated by |
+|---|---|---|
+| Active connections | AtomicU64 | `connection_opened/closed` |
+| Total connections (lifetime) | AtomicU64 | `connection_opened` |
+| Total bytes in | AtomicU64 | `record_bytes` |
+| Total bytes out | AtomicU64 | `record_bytes` |
+| Total HTTP requests | AtomicU64 | `record_http_request` |
+| Active UDP sessions | AtomicU64 | `udp_session_opened/closed` |
+| Total UDP sessions | AtomicU64 | `udp_session_opened` |
+| Total datagrams in | AtomicU64 | `record_datagram_in` |
+| Total datagrams out | AtomicU64 | `record_datagram_out` |
+
+### Per-Route Metrics (keyed by route ID string)
+
+| Metric | Storage |
+|---|---|
+| Active connections | `DashMap<String, AtomicU64>` |
+| Total connections | `DashMap<String, AtomicU64>` |
+| Bytes in / out | `DashMap<String, AtomicU64>` |
+| Pending throughput (in, out) | `DashMap<String, (AtomicU64, AtomicU64)>` |
+| Throughput history | `DashMap<String, Mutex<ThroughputTracker>>` |
+
+Entries are pruned via `retain_routes()` when routes are removed.
+
+### Per-IP Metrics (keyed by IP string)
+
+| Metric | Storage |
+|---|---|
+| Active connections | `DashMap<String, AtomicU64>` |
+| Total connections | `DashMap<String, AtomicU64>` |
+| Bytes in / out | `DashMap<String, AtomicU64>` |
+| Pending throughput (in, out) | `DashMap<String, (AtomicU64, AtomicU64)>` |
+| Throughput history | `DashMap<String, Mutex<ThroughputTracker>>` |
+| Domain requests | `DashMap<String, DashMap<String, AtomicU64>>` (IP → domain → count) |
+
+All seven maps for an IP are evicted when its active connection count drops to 0. Safety-net pruning in `sample_all()` catches entries orphaned by races. Snapshots cap at 100 IPs, sorted by active connections descending.
+
+**Domain request tracking:** Records which domains each frontend IP has requested. Populated from HTTP Host headers (for HTTP/1.1, HTTP/2, HTTP/3 requests) and from SNI (for TLS passthrough connections). Capped at 256 domains per IP (`MAX_DOMAINS_PER_IP`) to prevent subdomain-spray abuse. Inner DashMap uses 2 shards to minimise base memory per IP (~200 bytes). Common case (IP + domain both known) is two DashMap reads + one atomic increment with zero allocation.
+
+### Per-Backend Metrics (keyed by "host:port")
+
+| Metric | Storage |
+|---|---|
+| Active connections | `DashMap<String, AtomicU64>` |
+| Total connections | `DashMap<String, AtomicU64>` |
+| Detected protocol (h1/h2/h3) | `DashMap<String, String>` |
+| Connect errors | `DashMap<String, AtomicU64>` |
+| Handshake errors | `DashMap<String, AtomicU64>` |
+| Request errors | `DashMap<String, AtomicU64>` |
+| Total connect time (microseconds) | `DashMap<String, AtomicU64>` |
+| Connect count | `DashMap<String, AtomicU64>` |
+| Pool hits | `DashMap<String, AtomicU64>` |
+| Pool misses | `DashMap<String, AtomicU64>` |
+| H2 failures (fallback to H1) | `DashMap<String, AtomicU64>` |
+
+All per-backend maps are evicted when active count reaches 0. Pruned via `retain_backends()`.
+
+### Frontend Protocol Distribution
+
+Tracked via `ProtocolGuard` RAII guards and `FrontendProtocolTracker`. Five protocol categories, each with active + total counters (AtomicU64):
+
+| Protocol | Where detected |
+|---|---|
+| h1 | `FrontendProtocolTracker` on first HTTP/1.x request |
+| h2 | `FrontendProtocolTracker` on first HTTP/2 request |
+| h3 | `ProtocolGuard::frontend("h3")` in H3ProxyService |
+| ws | `ProtocolGuard::frontend("ws")` on WebSocket upgrade |
+| other | Fallback (TCP passthrough without HTTP) |
+
+Uses `fetch_update` for saturating decrements to prevent underflow races.
+
+### Backend Protocol Distribution
+
+Same five categories (h1/h2/h3/ws/other), tracked via `ProtocolGuard::backend()` at connection establishment. Backend h2 failures (fallback to h1) are separately counted.
+
+### Throughput History
+
+`ThroughputTracker` is a circular buffer storing `ThroughputSample { timestamp_ms, bytes_in, bytes_out }` at 1Hz.
+
+- Global tracker: 1 instance, default 3600 capacity
+- Per-route trackers: 1 per active route
+- Per-IP trackers: 1 per connected IP (evicted with the IP)
+- HTTP request tracker: reuses ThroughputTracker with bytes_in = request count, bytes_out = 0
+
+Query methods:
+- `instant()` — last 1 second average
+- `recent()` — last 10 seconds average
+- `throughput(N)` — last N seconds average
+- `history(N)` — last N raw samples in chronological order
+
+Snapshots return 60 samples of global throughput history.
+
+### Protocol Detection Cache
+
+Not part of MetricsCollector. Maintained by `HttpProxyService`'s protocol detection system. Injected into the metrics snapshot at read time by `get_metrics()`.
+
+Each entry records: host, port, domain, detected protocol (h1/h2/h3), H3 port, age, last accessed, last probed, suppression flags, cooldown timers, consecutive failure counts.
+
+---
+
+## Instrumentation Points
+
+### TCP Passthrough (`rustproxy-passthrough`)
+
+**Connection lifecycle** — `tcp_listener.rs`:
+- Accept: `conn_tracker.connection_opened(&ip)` (rate limiter) + `ConnectionTrackerGuard` RAII
+- Route match: `metrics.connection_opened(route_id, source_ip)` + `ConnectionGuard` RAII
+- Close: Both guards call their respective `_closed()` methods on drop
+
+**Byte recording** — `forwarder.rs` (`forward_bidirectional_with_timeouts`):
+- Initial peeked data recorded immediately
+- Per-chunk in both directions: `record_bytes(n, 0, ...)` / `record_bytes(0, n, ...)`
+- Same pattern in `forward_bidirectional_split_with_timeouts` (tcp_listener.rs) for TLS-terminated paths
+
+### HTTP Proxy (`rustproxy-http`)
+
+**Request counting** — `proxy_service.rs`:
+- `record_http_request()` called once per request after route matching succeeds
+
+**Body byte counting** — `counting_body.rs` wrapping:
+- Request bodies: `CountingBody::new(body, ..., Direction::In)` — counts client-to-upstream bytes
+- Response bodies: `CountingBody::new(body, ..., Direction::Out)` — counts upstream-to-client bytes
+- Batched flush every 64KB (`BYTE_FLUSH_THRESHOLD = 65_536`), remainder flushed on drop
+- Also updates `connection_activity` atomic (idle watchdog) and `active_requests` counter (streaming detection)
+
+**Backend metrics** — `proxy_service.rs`:
+- `backend_connection_opened(key, connect_time)` — after TCP/TLS connect succeeds
+- `backend_connection_closed(key)` — on teardown
+- `backend_connect_error(key)` — TCP/TLS connect failure or timeout
+- `backend_handshake_error(key)` — H1/H2 protocol handshake failure
+- `backend_request_error(key)` — send_request failure
+- `backend_h2_failure(key)` — H2 attempted, fell back to H1
+- `backend_pool_hit(key)` / `backend_pool_miss(key)` — connection pool reuse
+- `set_backend_protocol(key, proto)` — records detected protocol
+
+**WebSocket** — `proxy_service.rs`:
+- Does NOT use CountingBody; records bytes directly per-chunk in both directions of the bidirectional copy loop
+
+### QUIC (`rustproxy-passthrough`)
+
+**Connection level** — `quic_handler.rs`:
+- `connection_opened` / `connection_closed` via `QuicConnGuard` RAII
+- `conn_tracker.connection_opened/closed` for rate limiting
+
+**Stream level**:
+- For QUIC-to-TCP stream forwarding: `record_bytes(bytes_in, bytes_out, ...)` called once per stream at completion (post-hoc, not per-chunk)
+- For HTTP/3: delegates to `HttpProxyService.handle_request()`, so all HTTP proxy metrics apply
+
+**H3 specifics** — `h3_service.rs`:
+- `ProtocolGuard::frontend("h3")` tracks the H3 connection
+- H3 request bodies: `record_bytes(data.len(), 0, ...)` called directly (not CountingBody) since H3 uses `stream.send_data()`
+- H3 response bodies: wrapped in CountingBody like HTTP/1 and HTTP/2
+
+### UDP (`rustproxy-passthrough`)
+
+**Session lifecycle** — `udp_listener.rs` / `udp_session.rs`:
+- `udp_session_opened()` + `connection_opened(route_id, source_ip)` on new session
+- `udp_session_closed()` + `connection_closed(route_id, source_ip)` on idle reap or port drain
+
+**Datagram counting** — `udp_listener.rs`:
+- Inbound: `record_bytes(len, 0, ...)` + `record_datagram_in()`
+- Outbound (backend reply): `record_bytes(0, len, ...)` + `record_datagram_out()`
+
+---
+
+## Sampling Loop
+
+`lib.rs` spawns a tokio task at configurable interval (default 1000ms):
+
+```rust
+loop {
+    tokio::select! {
+        _ = cancel => break,
+        _ = interval.tick() => {
+            metrics.sample_all();
+            conn_tracker.cleanup_stale_timestamps();
+            http_proxy.cleanup_all_rate_limiters();
+        }
+    }
+}
+```
+
+`sample_all()` performs in one pass:
+1. Drains `global_pending_tp_in/out` into global ThroughputTracker, samples
+2. Drains per-route pending counters into per-route trackers, samples each
+3. Samples idle route trackers (no new data) to advance their window
+4. Drains per-IP pending counters into per-IP trackers, samples each
+5. Drains `pending_http_requests` into HTTP request throughput tracker
+6. Prunes orphaned per-IP entries (bytes/throughput maps with no matching ip_connections key)
+7. Prunes orphaned per-backend entries (error/stats maps with no matching active/total key)
+
+---
+
+## Data Flow: Rust to TypeScript
+
+```
+MetricsCollector.snapshot()
+    ├── reads all AtomicU64 counters
+    ├── iterates DashMaps (routes, IPs, backends)
+    ├── locks ThroughputTrackers for instant/recent rates + history
+    └── produces Metrics struct
+
+RustProxy::get_metrics()
+    ├── calls snapshot()
+    ├── enriches with detectedProtocols from HTTP proxy protocol cache
+    └── returns Metrics
+
+management.rs "getMetrics" IPC command
+    ├── calls get_metrics()
+    ├── serde_json::to_value (camelCase)
+    └── writes JSON to stdout
+
+RustProxyBridge (TypeScript)
+    ├── reads JSON from Rust process stdout
+    └── returns parsed object
+
+RustMetricsAdapter
+    ├── setInterval polls bridge.getMetrics() every 1s
+    ├── stores raw JSON in this.cache
+    └── IMetrics methods read synchronously from cache
+
+SmartProxy.getMetrics()
+    └── returns the RustMetricsAdapter instance
+```
+
+### IPC JSON Shape (Metrics)
+
+```json
+{
+  "activeConnections": 42,
+  "totalConnections": 1000,
+  "bytesIn": 123456789,
+  "bytesOut": 987654321,
+  "throughputInBytesPerSec": 50000,
+  "throughputOutBytesPerSec": 80000,
+  "throughputRecentInBytesPerSec": 45000,
+  "throughputRecentOutBytesPerSec": 75000,
+  "routes": {
+    "<route-id>": {
+      "activeConnections": 5,
+      "totalConnections": 100,
+      "bytesIn": 0, "bytesOut": 0,
+      "throughputInBytesPerSec": 0, "throughputOutBytesPerSec": 0,
+      "throughputRecentInBytesPerSec": 0, "throughputRecentOutBytesPerSec": 0
+    }
+  },
+  "ips": {
+    "<ip>": {
+      "activeConnections": 2, "totalConnections": 10,
+      "bytesIn": 0, "bytesOut": 0,
+      "throughputInBytesPerSec": 0, "throughputOutBytesPerSec": 0,
+      "domainRequests": {
+        "example.com": 4821,
+        "api.example.com": 312
+      }
+    }
+  },
+  "backends": {
+    "<host:port>": {
+      "activeConnections": 3, "totalConnections": 50,
+      "protocol": "h2",
+      "connectErrors": 0, "handshakeErrors": 0, "requestErrors": 0,
+      "totalConnectTimeUs": 150000, "connectCount": 50,
+      "poolHits": 40, "poolMisses": 10, "h2Failures": 1
+    }
+  },
+  "throughputHistory": [
+    { "timestampMs": 1713000000000, "bytesIn": 50000, "bytesOut": 80000 }
+  ],
+  "totalHttpRequests": 5000,
+  "httpRequestsPerSec": 100,
+  "httpRequestsPerSecRecent": 95,
+  "activeUdpSessions": 0, "totalUdpSessions": 5,
+  "totalDatagramsIn": 1000, "totalDatagramsOut": 1000,
+  "frontendProtocols": {
+    "h1Active": 10, "h1Total": 500,
+    "h2Active": 5, "h2Total": 200,
+    "h3Active": 1, "h3Total": 50,
+    "wsActive": 2, "wsTotal": 30,
+    "otherActive": 0, "otherTotal": 0
+  },
+  "backendProtocols": { "...same shape..." },
+  "detectedProtocols": [
+    {
+      "host": "backend", "port": 443, "domain": "example.com",
+      "protocol": "h2", "h3Port": 443,
+      "ageSecs": 120, "lastAccessedSecs": 5, "lastProbedSecs": 120,
+      "h2Suppressed": false, "h3Suppressed": false,
+      "h2CooldownRemainingSecs": null, "h3CooldownRemainingSecs": null,
+      "h2ConsecutiveFailures": null, "h3ConsecutiveFailures": null
+    }
+  ]
+}
+```
+
+### IPC JSON Shape (Statistics)
+
+Lightweight administrative summary, fetched on-demand (not polled):
+
+```json
+{
+  "activeConnections": 42,
+  "totalConnections": 1000,
+  "routesCount": 5,
+  "listeningPorts": [80, 443, 8443],
+  "uptimeSeconds": 86400
+}
+```
+
+---
+
+## TypeScript Consumer API
+
+`SmartProxy.getMetrics()` returns an `IMetrics` object. All members are synchronous methods reading from the polled cache.
+
+### connections
+
+| Method | Return | Source |
+|---|---|---|
+| `active()` | `number` | `cache.activeConnections` |
+| `total()` | `number` | `cache.totalConnections` |
+| `byRoute()` | `Map<string, number>` | `cache.routes[name].activeConnections` |
+| `byIP()` | `Map<string, number>` | `cache.ips[ip].activeConnections` |
+| `topIPs(limit?)` | `Array<{ip, count}>` | `cache.ips` sorted by active desc, default 10 |
+| `domainRequestsByIP()` | `Map<string, Map<string, number>>` | `cache.ips[ip].domainRequests` |
+| `topDomainRequests(limit?)` | `Array<{ip, domain, count}>` | Flattened from all IPs, sorted by count desc, default 20 |
+| `frontendProtocols()` | `IProtocolDistribution` | `cache.frontendProtocols.*` |
+| `backendProtocols()` | `IProtocolDistribution` | `cache.backendProtocols.*` |
+
+### throughput
+
+| Method | Return | Source |
+|---|---|---|
+| `instant()` | `{in, out}` | `cache.throughputInBytesPerSec/Out` |
+| `recent()` | `{in, out}` | `cache.throughputRecentInBytesPerSec/Out` |
+| `average()` | `{in, out}` | Falls back to `instant()` (not wired to windowed average) |
+| `custom(seconds)` | `{in, out}` | Falls back to `instant()` (not wired) |
+| `history(seconds)` | `IThroughputHistoryPoint[]` | `cache.throughputHistory` sliced to last N entries |
+| `byRoute(windowSeconds?)` | `Map<string, {in, out}>` | `cache.routes[name].throughputIn/OutBytesPerSec` |
+| `byIP(windowSeconds?)` | `Map<string, {in, out}>` | `cache.ips[ip].throughputIn/OutBytesPerSec` |
+
+### requests
+
+| Method | Return | Source |
+|---|---|---|
+| `perSecond()` | `number` | `cache.httpRequestsPerSec` |
+| `perMinute()` | `number` | `cache.httpRequestsPerSecRecent * 60` |
+| `total()` | `number` | `cache.totalHttpRequests` (fallback: totalConnections) |
+
+### totals
+
+| Method | Return | Source |
+|---|---|---|
+| `bytesIn()` | `number` | `cache.bytesIn` |
+| `bytesOut()` | `number` | `cache.bytesOut` |
+| `connections()` | `number` | `cache.totalConnections` |
+
+### backends
+
+| Method | Return | Source |
+|---|---|---|
+| `byBackend()` | `Map<string, IBackendMetrics>` | `cache.backends[key].*` with computed `avgConnectTimeMs` and `poolHitRate` |
+| `protocols()` | `Map<string, string>` | `cache.backends[key].protocol` |
+| `topByErrors(limit?)` | `IBackendMetrics[]` | Sorted by total errors desc |
+| `detectedProtocols()` | `IProtocolCacheEntry[]` | `cache.detectedProtocols` passthrough |
+
+`IBackendMetrics`: `{ protocol, activeConnections, totalConnections, connectErrors, handshakeErrors, requestErrors, avgConnectTimeMs, poolHitRate, h2Failures }`
+
+### udp
+
+| Method | Return | Source |
+|---|---|---|
+| `activeSessions()` | `number` | `cache.activeUdpSessions` |
+| `totalSessions()` | `number` | `cache.totalUdpSessions` |
+| `datagramsIn()` | `number` | `cache.totalDatagramsIn` |
+| `datagramsOut()` | `number` | `cache.totalDatagramsOut` |
+
+### percentiles (stub)
+
+`connectionDuration()` and `bytesTransferred()` always return zeros. Not implemented.
+
+---
+
+## Configuration
+
+```typescript
+interface IMetricsConfig {
+  enabled: boolean;              // default true
+  sampleIntervalMs: number;      // default 1000 (1Hz sampling + TS polling)
+  retentionSeconds: number;      // default 3600 (ThroughputTracker capacity)
+  enableDetailedTracking: boolean;
+  enablePercentiles: boolean;
+  cacheResultsMs: number;
+  prometheusEnabled: boolean;    // not wired
+  prometheusPath: string;        // not wired
+  prometheusPrefix: string;      // not wired
+}
+```
+
+Rust-side config (`MetricsConfig` in `rustproxy-config`):
+
+```rust
+pub struct MetricsConfig {
+    pub enabled: Option<bool>,
+    pub sample_interval_ms: Option<u64>,   // default 1000
+    pub retention_seconds: Option<u64>,    // default 3600
+}
+```
+
+---
+
+## Design Decisions
+
+**Lock-free hot path.** `record_bytes()` is the most frequently called method (per-chunk in TCP, per-64KB in HTTP). It only touches `AtomicU64` with `Relaxed` ordering and short-circuits zero-byte directions to skip DashMap lookups entirely.
+
+**CountingBody batching.** HTTP body frames are typically 16KB. Flushing to MetricsCollector every 64KB reduces DashMap shard contention by ~4x compared to per-frame recording.
+
+**RAII guards everywhere.** `ConnectionGuard`, `ConnectionTrackerGuard`, `QuicConnGuard`, `ProtocolGuard`, `FrontendProtocolTracker` all use Drop to guarantee counter cleanup on all exit paths including panics.
+
+**Saturating decrements.** Protocol counters use `fetch_update` loops instead of `fetch_sub` to prevent underflow to `u64::MAX` from concurrent close races.
+
+**Bounded memory.** Per-IP entries evicted on last connection close. Per-backend entries evicted on last connection close. Snapshot caps IPs and backends at 100 each. `sample_all()` prunes orphaned entries every second.
+
+**Two-phase throughput.** Pending bytes accumulate in lock-free atomics. The 1Hz cold path drains them into Mutex-guarded ThroughputTrackers. This means the hot path never contends on a Mutex, while the cold path does minimal work (one drain + one sample per tracker).
+
+---
+
+## Known Gaps
+
+| Gap | Status |
+|---|---|
+| `throughput.average()` / `throughput.custom(seconds)` | Fall back to `instant()`. Not wired to Rust windowed queries. |
+| `percentiles.connectionDuration()` / `percentiles.bytesTransferred()` | Stub returning zeros. No histogram in Rust. |
+| Prometheus export | Config fields exist but not wired to any exporter. |
+| `LogDeduplicator` | Implemented in `rustproxy-metrics` but not connected to any call site. |
+| Rate limit hit counters | Rate-limited requests return 429 but no counter is recorded in MetricsCollector. |
+| QUIC stream byte counting | Post-hoc (per-stream totals after close), not per-chunk like TCP. |
+| Throughput history in snapshot | Capped at 60 samples. TS `history(seconds)` cannot return more than 60 points regardless of `retentionSeconds`. |
+| Per-route total connections / bytes | Available in Rust JSON but `IMetrics.connections.byRoute()` only exposes active connections. |
+| Per-IP total connections / bytes | Available in Rust JSON but `IMetrics.connections.byIP()` only exposes active connections. |
+| IPC response typing | `RustProxyBridge` declares `result: any` for both metrics commands. No type-safe response. |

rust/crates/rustproxy-http/src/proxy_service.rs

@@ -626,6 +626,9 @@ impl HttpProxyService {
         let route_id = route_match.route.id.as_deref();
         let ip_str = ip_string; // reuse from above (avoid redundant to_string())
         self.metrics.record_http_request();
+        if let Some(ref h) = host {
+            self.metrics.record_ip_domain_request(&ip_str, h);
+        }
 
         // Apply request filters (IP check, rate limiting, auth)
         if let Some(ref security) = route_match.route.security {

rust/crates/rustproxy-metrics/src/collector.rs

@@ -1,6 +1,6 @@
 use dashmap::DashMap;
 use serde::{Deserialize, Serialize};
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::Mutex;
 use std::time::Duration;
@@ -62,6 +62,8 @@ pub struct IpMetrics {
     pub bytes_out: u64,
     pub throughput_in_bytes_per_sec: u64,
     pub throughput_out_bytes_per_sec: u64,
+    /// Per-domain request/connection counts for this IP.
+    pub domain_requests: HashMap<String, u64>,
 }
 
 /// Per-backend metrics (keyed by "host:port").
@@ -139,6 +141,9 @@ const MAX_IPS_IN_SNAPSHOT: usize = 100;
 /// Maximum number of backends to include in a snapshot (top by total connections).
 const MAX_BACKENDS_IN_SNAPSHOT: usize = 100;
 
+/// Maximum number of distinct domains tracked per IP (prevents subdomain-spray abuse).
+const MAX_DOMAINS_PER_IP: usize = 256;
+
 /// Metrics collector tracking connections and throughput.
 ///
 /// Design: The hot path (`record_bytes`) is entirely lock-free — it only touches
@@ -165,6 +170,10 @@ pub struct MetricsCollector {
     ip_bytes_out: DashMap<String, AtomicU64>,
     ip_pending_tp: DashMap<String, (AtomicU64, AtomicU64)>,
     ip_throughput: DashMap<String, Mutex<ThroughputTracker>>,
+    /// Per-IP domain request counts: IP → { domain → count }.
+    /// Tracks which domains each frontend IP has requested (via HTTP Host/SNI).
+    /// Inner DashMap uses 2 shards to minimise base memory per IP.
+    ip_domain_requests: DashMap<String, DashMap<String, AtomicU64>>,
 
     // ── Per-backend tracking (keyed by "host:port") ──
     backend_active: DashMap<String, AtomicU64>,
@@ -247,6 +256,7 @@ impl MetricsCollector {
             ip_bytes_out: DashMap::new(),
             ip_pending_tp: DashMap::new(),
             ip_throughput: DashMap::new(),
+            ip_domain_requests: DashMap::new(),
             backend_active: DashMap::new(),
             backend_total: DashMap::new(),
             backend_protocol: DashMap::new(),
@@ -351,6 +361,7 @@ impl MetricsCollector {
                     self.ip_bytes_out.remove(ip);
                     self.ip_pending_tp.remove(ip);
                     self.ip_throughput.remove(ip);
+                    self.ip_domain_requests.remove(ip);
                 }
             }
         }
@@ -452,6 +463,37 @@ impl MetricsCollector {
         self.pending_http_requests.fetch_add(1, Ordering::Relaxed);
     }
 
+    /// Record a domain request/connection for a frontend IP.
+    ///
+    /// Called per HTTP request (with Host header) and per TCP passthrough
+    /// connection (with SNI domain). The common case (IP + domain both already
+    /// tracked) is two DashMap reads + one atomic increment — zero allocation.
+    pub fn record_ip_domain_request(&self, ip: &str, domain: &str) {
+        // Fast path: IP already tracked, domain already tracked
+        if let Some(domains) = self.ip_domain_requests.get(ip) {
+            if let Some(counter) = domains.get(domain) {
+                counter.fetch_add(1, Ordering::Relaxed);
+                return;
+            }
+            // New domain for this IP — enforce cap
+            if domains.len() >= MAX_DOMAINS_PER_IP {
+                return;
+            }
+            domains
+                .entry(domain.to_string())
+                .or_insert_with(|| AtomicU64::new(0))
+                .fetch_add(1, Ordering::Relaxed);
+            return;
+        }
+        // New IP — only create if the IP has active connections
+        if !self.ip_connections.contains_key(ip) {
+            return;
+        }
+        let inner = DashMap::with_capacity_and_shard_amount(4, 2);
+        inner.insert(domain.to_string(), AtomicU64::new(1));
+        self.ip_domain_requests.insert(ip.to_string(), inner);
+    }
+
     // ── UDP session recording methods ──
 
     /// Record a new UDP session opened.
@@ -745,6 +787,7 @@ impl MetricsCollector {
         self.ip_pending_tp.retain(|k, _| self.ip_connections.contains_key(k));
         self.ip_throughput.retain(|k, _| self.ip_connections.contains_key(k));
         self.ip_total_connections.retain(|k, _| self.ip_connections.contains_key(k));
+        self.ip_domain_requests.retain(|k, _| self.ip_connections.contains_key(k));
 
         // Safety-net: prune orphaned backend error/stats entries for backends
         // that have no active or total connections (error-only backends).
@@ -852,7 +895,7 @@ impl MetricsCollector {
 
         // Collect per-IP metrics — only IPs with active connections or total > 0,
         // capped at top MAX_IPS_IN_SNAPSHOT sorted by active count
-        let mut ip_entries: Vec<(String, u64, u64, u64, u64, u64, u64)> = Vec::new();
+        let mut ip_entries: Vec<(String, u64, u64, u64, u64, u64, u64, HashMap<String, u64>)> = Vec::new();
         for entry in self.ip_total_connections.iter() {
             let ip = entry.key().clone();
             let total = entry.value().load(Ordering::Relaxed);
@@ -872,14 +915,23 @@ impl MetricsCollector {
                 .get(&ip)
                 .and_then(|entry| entry.value().lock().ok().map(|t| t.instant()))
                 .unwrap_or((0, 0));
-            ip_entries.push((ip, active, total, bytes_in, bytes_out, tp_in, tp_out));
+            // Collect per-domain request counts for this IP
+            let domain_requests = self.ip_domain_requests
+                .get(&ip)
+                .map(|domains| {
+                    domains.iter()
+                        .map(|e| (e.key().clone(), e.value().load(Ordering::Relaxed)))
+                        .collect()
+                })
+                .unwrap_or_default();
+            ip_entries.push((ip, active, total, bytes_in, bytes_out, tp_in, tp_out, domain_requests));
         }
         // Sort by active connections descending, then cap
         ip_entries.sort_by(|a, b| b.1.cmp(&a.1));
         ip_entries.truncate(MAX_IPS_IN_SNAPSHOT);
 
         let mut ips = std::collections::HashMap::new();
-        for (ip, active, total, bytes_in, bytes_out, tp_in, tp_out) in ip_entries {
+        for (ip, active, total, bytes_in, bytes_out, tp_in, tp_out, domain_requests) in ip_entries {
             ips.insert(ip, IpMetrics {
                 active_connections: active,
                 total_connections: total,
@@ -887,6 +939,7 @@ impl MetricsCollector {
                 bytes_out,
                 throughput_in_bytes_per_sec: tp_in,
                 throughput_out_bytes_per_sec: tp_out,
+                domain_requests,
             });
         }
 

rust/crates/rustproxy-passthrough/src/tcp_listener.rs

@@ -943,6 +943,9 @@ impl TcpListenerManager {
 
         // Track connection in metrics — guard ensures connection_closed on all exit paths
         metrics.connection_opened(route_id, Some(&ip_str));
+        if let Some(d) = effective_domain {
+            metrics.record_ip_domain_request(&ip_str, d);
+        }
         let _conn_guard = ConnectionGuard::new(Arc::clone(&metrics), route_id, Some(&ip_str));
 
         // Check if this is a socket-handler route that should be relayed to TypeScript

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '27.5.0',
+  version: '27.6.0',
   description: 'A powerful proxy package with unified route-based configuration for high traffic management. Features include SSL/TLS support, flexible routing patterns, WebSocket handling, advanced security options, and automatic ACME certificate management.'
 }

ts/proxies/smart-proxy/models/metrics-types.ts

@@ -57,6 +57,10 @@ export interface IMetrics {
     byRoute(): Map<string, number>;
     byIP(): Map<string, number>;
     topIPs(limit?: number): Array<{ ip: string; count: number }>;
+    /** Per-IP domain request counts: IP -> { domain -> count }. */
+    domainRequestsByIP(): Map<string, Map<string, number>>;
+    /** Top IP-domain pairs sorted by request count descending. */
+    topDomainRequests(limit?: number): Array<{ ip: string; domain: string; count: number }>;
     frontendProtocols(): IProtocolDistribution;
     backendProtocols(): IProtocolDistribution;
   };

ts/proxies/smart-proxy/rust-metrics-adapter.ts

@@ -90,6 +90,39 @@ export class RustMetricsAdapter implements IMetrics {
       result.sort((a, b) => b.count - a.count);
       return result.slice(0, limit);
     },
+    domainRequestsByIP: (): Map<string, Map<string, number>> => {
+      const result = new Map<string, Map<string, number>>();
+      if (this.cache?.ips) {
+        for (const [ip, im] of Object.entries(this.cache.ips)) {
+          const dr = (im as any).domainRequests;
+          if (dr && typeof dr === 'object') {
+            const domainMap = new Map<string, number>();
+            for (const [domain, count] of Object.entries(dr)) {
+              domainMap.set(domain, count as number);
+            }
+            if (domainMap.size > 0) {
+              result.set(ip, domainMap);
+            }
+          }
+        }
+      }
+      return result;
+    },
+    topDomainRequests: (limit: number = 20): Array<{ ip: string; domain: string; count: number }> => {
+      const result: Array<{ ip: string; domain: string; count: number }> = [];
+      if (this.cache?.ips) {
+        for (const [ip, im] of Object.entries(this.cache.ips)) {
+          const dr = (im as any).domainRequests;
+          if (dr && typeof dr === 'object') {
+            for (const [domain, count] of Object.entries(dr)) {
+              result.push({ ip, domain, count: count as number });
+            }
+          }
+        }
+      }
+      result.sort((a, b) => b.count - a.count);
+      return result.slice(0, limit);
+    },
     frontendProtocols: (): IProtocolDistribution => {
       const fp = this.cache?.frontendProtocols;
       return {