tuliprox/docs/src/configuration/reverse-proxy.md

# 🌊 Reverse Proxy (Streaming, Caching & Rate Limits)

This section documents the `reverse_proxy:` block inside `config.yml`.
It is the most critical block for determining runtime behavior when Tuliprox actively proxies video streams
to clients (Reverse Proxy Mode), rather than just redirecting them.

It manages how Tuliprox establishes upstream connections, buffers video frames, handles sudden client disconnects,
and caches static resources like EPG images and channel logos.

It also contains the optional telemetry pipeline for stream reliability analysis:

* `stream_history` stores raw stream lifecycle events on disk.
* `qos_aggregation` periodically condenses those raw events into compact QoS snapshots.
* The Web UI can then inspect both the raw history view and the aggregated QoS summaries.

## Read This First: Connection Handling Handbook

The `reverse_proxy.stream` block now interacts with a broader connection-handling model:

* user limits
* soft connections
* priorities
* admission strategies
* grace periods
* HLS and catchup sessions
* shared streams
* provider-side preemption

If you want to understand why a stream starts, waits, gets reused, gets preempted, or is rejected, read these pages first:

* [Connection Handling](./connection-handling.md)
* [Connection Handling: Priorities, Soft Connections and Preemption](./connection-handling-priorities-and-preemption.md)
* [Connection Handling: Sessions, HLS, Catchup and Reconnects](./connection-handling-sessions-and-reconnects.md)
* [Connection Handling: Failures and User-Visible Behavior](./connection-handling-failures-and-user-visible-behavior.md)

## Top-level entries

```yaml
reverse_proxy:
  resource_rewrite_disabled: false
  rewrite_secret: A1B2C3D4E5F60718293A4B5C6D7E8F90
  stream:
  cache:
  hls_cache:
  rate_limit:
  disabled_header:
  resource_retry:
  geoip:
  stream_history:
  qos_aggregation:
```

> **Note:** Reverse Proxy mode can be activated for each user individually.

### General Parameters

| Parameter | Type | Default | Technical Impact & Background |
| :--- | :--- | :--- | :--- |
| `resource_rewrite_disabled` | Bool | `false` | Normally, Tuliprox rewrites all image URLs in playlists to point to itself (e.g., `http://tuliprox:8901/resource/...`). If set to `true`, original URLs are kept (clients load images directly from the provider). **Warning:** Local caching will stop working if this is enabled! |
| `rewrite_secret` | String | `""` | A 32-character Hex string (16 bytes). Tuliprox encrypts/signs the original image URLs during the rewrite process. To prevent image URLs from becoming invalid after a server restart, you MUST enter a static secret here. |
| `stream_history` | Block | `null` | Optional stream telemetry block that persists raw connect/disconnect/startup-failure events to daily history files. |
| `qos_aggregation` | Block | `null` | Optional background worker that aggregates stream history into compact per-stream QoS snapshots. |

> **Note:** You can generate a random secret using:

```bash
openssl rand -hex 16
# or
node -e "console.log(require('crypto').randomBytes(16).toString('hex').toUpperCase())"
```

---

## 1. Stream Management (`stream`)

This sub-block defines how Tuliprox maintains stream stability, buffers data, and handles HLS/Catchup session affinity.

Admission strategies in this block can optionally evict an existing stream after normal and soft user admission are already exhausted:

* `evict_user_same_ip_oldest`
* `evict_user_same_ip_latest`
* `evict_user_oldest`
* `evict_user_latest`
* `grace_instant_stream`
* `grace_hold_stream`

Order matters.

If you want same-IP eviction to be preferred, place the same-IP rule before the broader user-wide rule with the same oldest/latest policy.

Examples:

* valid: `evict_user_same_ip_oldest`, then `evict_user_oldest`
* invalid: `evict_user_oldest`, then `evict_user_same_ip_oldest`
* valid: `evict_user_same_ip_latest`, then `evict_user_latest`
* invalid: `evict_user_latest`, then `evict_user_same_ip_latest`

```yaml
reverse_proxy:
  stream:
    retry: true
    buffer:
      enabled: true
      size: 1024
    throttle_kbps: 12500
    grace_period_millis: 2000
    grace_period_timeout_secs: 4
    grace_period_hold_stream: true
    hls_session_ttl_secs: 15
    catchup_session_ttl_secs: 45
    shared_burst_buffer_mb: 12
    metrics_enabled: false
```

### Stream Parameters in Detail

| Parameter | Type | Default | Technical Impact & Background |
| :--- | :--- | :--- | :--- |
| `retry` | Bool | `true` | Retries connecting to the upstream provider during the initial stream open when the provider returns a transient failure or no usable stream. Once a stream has started, Tuliprox does not transparently replace that live upstream inside the same client response. |
| `buffer.enabled` | Bool | `false` | Enables an asynchronous ring-buffer in RAM between the provider download stream and the client upload stream. Necessary if the provider stream is faster than the consumer can process. |
| `buffer.size` | Int | `0` | The size of the buffer in *Chunks* (1 Chunk = 8192 Bytes). A value of `1024` equals approximately 8 Megabytes of RAM per active stream. |
| `throttle_kbps` | Int | `0` | **Background:** Some players download VODs (Movies) at maximum line speed ("Bursting"). Providers often view this as abuse or scraping and will ban the IP. By throttling (e.g., to `12500` kbps), you force the download into a constant, inconspicuous flow. Supports units like `KB/s`, `MB/s`, `kbps`, `Mibps`. |
| `metrics_enabled` | Bool | `false` | **Monitoring:** If active, Tuliprox samples the live bandwidth (in kbps) and transferred bytes for every active reverse-proxied stream and pushes them via WebSockets to the Web UI. It adds a tiny bit of CPU overhead but is invaluable for debugging buffering issues. |
| `grace_period_millis` | Int | `2000` | The exact time window in ms where a temporary over-allocation is allowed (see notes on [The VLC Seek Problem](#the-vlc-seek-problem--grace-periods) for details). |
| `grace_period_timeout_secs` | Int | `4` | A hard timeout limit for overlapping "ghost sessions" to expire. |
| `grace_period_hold_stream` | Bool | `true` | Tuliprox artificially holds back video data to the client, waiting for grace check to finish, so it doesn't trigger provider prematurely. |
| `hls_session_ttl_secs` | Int | `15` | Keeps virtual provider slot open between HLS segment (`.ts`) requests to prevent provider bans for "Account Hopping". |
| `catchup_session_ttl_secs` | Int | `45` | Same session-holding principle applied to Archive/Catchup TV. See notes on section [Session TTLs for HLS & Catchup](#session-ttls-for-hls-m3u8--catchup) for details. |
| `shared_burst_buffer_mb` | Int | `12` | Minimum burst buffer size (in MB) used for shared live streams to immediately synchronize new clients without Keyframe dropouts. See notes on section [Shared Live Streams](#shared-live-streams) for details. |

### 1.1 `retry` & `buffer` (Deep Dive)

Tuliprox handles streams differently based on these settings:

* **Option A:** Both `retry: false` and `buffer.enabled: false` ➔ The provider stream is piped directly to the client with  
  minimal overhead.
* **Option B:** `retry: true` retries transient failures while opening the provider stream. `buffer.enabled: true` adds  
  buffered streaming with a higher memory footprint.

Stream-type provider behavior:

* Plain TS live is socket/request-oriented. A new TS reconnect is a new provider allocation and may use another provider
  account if the selected account is unavailable.
* Initial stream-open retries may also rotate configured provider URLs/accounts when failover is enabled.
* HLS, DASH, VOD, series, and catchup are provider-affine after a session exists. Follow-up segment, seek, range, or  
  reopen requests must stay on the provider account pinned in that session; if that account is unavailable, Tuliprox  
  fails the follow-up instead of silently migrating it.
* `retry: false` disables stream-open retry/failover for stream requests.

#### Ring-Buffer Calculation

`buffer.size` is defined in chunks of **8192 bytes (8 KB)**.

* A size of `1024` equals approx. **8 MB** of RAM per active stream.
* **Shared Streams Impact:** If `share_live_streams.mpeg_ts` is enabled, each channel consumes at least **12 MB** regardless of client count.
  Increasing `size` above 1024 (e.g., 2048) increases this to **24 MB** per shared channel.

### 1.2 `throttle_kbps`

Prevents provider bans by limiting "bursting" players. Supported units: `KB/s`, `MB/s`, `KiB/s`, `MiB/s`, `kbps`, `mbps`, `Mibps`.

**Reference Table for Throttling:**

| Resolution | Framerate | Bitrate (kbps) | Quality |
| :--- | :--- | :--- | :--- |
| 480p (854x480) | 30 fps | 819 – 2,457 | Low-Quality |
| 720p (1280x720) | 30 fps | 2,457 – 5,737 | HD-Streams |
| 1080p (1920x1080) | 30 fps | 5,737 – 12,288 | Full-HD |
| 4K (3840x2160) | 30 fps | 20,480 – 49,152 | Ultra-HD |

### 1.3 `grace_period` (The VLC Seek Problem)

If `max_connections` is > 0, seeking can trigger a 509/401 error because the old connection isn't closed yet.

* `grace_period_millis` (Default: `2000`): Grants a temporary over-allocation during switchover.
* `grace_period_timeout_secs` (Default: `4`): How long a grace grant lasts before a new one can be made.
* `grace_period_hold_stream`: If `true`, Tuliprox waits for the check to complete before sending data,
  preventing player timeouts on "exhausted" switches.

### 1.4 HLS & Catchup Session TTLs

HLS/Catchup clients connect and disconnect repeatedly. Tuliprox uses a **Virtual Reservation**
to maintain account affinity:

* **HLS (`15s`):** The real provider slot is only held during active requests.
  The reservation keeps the provider account stable between segment fetches.
* **Catchup (`45s`):** Keeps the reservation alive during seeking and reconnects.
* **Note:** Channel switches from the same client immediately take over the reservation, bypassing the TTL.

Important boundary:

* These TTLs are for HLS/catchup style session continuity.
* Regular TS/VOD/local playback is socket-bound for admission and user-connection counting.
* Opening the same TS/VOD stream on a second socket consumes another connection or soft slot.

---

## 2. Resource Caching (`cache`)

Tuliprox maintains a local disk cache for channel logos, posters, and EPG images.
This reduces the load on provider servers and significantly speeds up playlist loading times for your clients.

```yaml
reverse_proxy:
  cache:
    enabled: true
    size: 1GB
    directory: ./cache
```

### Cache Parameter Details

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `enabled` | Bool | `false` | Global switch for resource caching. **Note:** Requires `resource_rewrite_disabled: false`. |
| `size` | Size | `1GB` | Maximum disk space allocation. Supported units: `KB`, `MB`, `GB`, `TB`. |
| `directory` | String | `./cache` | Storage location. Relative paths are resolved against the `storage_dir`. |

### Technical Background

* **LRU Logic:** Operates as a **Least Recently Used** cache. When the `size` limit is reached, Tuliprox automatically evicts
  the oldest/least accessed images to make room for new content.
* **Encryption:** Cached resources are indexed using a hash derived from the `rewrite_secret`.
  If the secret changes, the old cache becomes orphaned.
* **Client Delivery:** Instead of the client downloading directly from the provider, Tuliprox serves the local file,
  acting as a high-speed CDN for your media metadata.

---

## 2.1 HLS Cache (`hls_cache`)

This block configures the Live HLS cache proxy. It only defines operating parameters.
For an operator-friendly explanation, start with [Shared HLS Sessions](./shared-hls-sessions.md).
For the configuration reference, see [Shared HLS Configuration](./shared-hls-configuration.md).
For the shared session, access lease, and transient delivery state machines, see
[HLS Cache State Machines](./hls-cache-state-machine.md).

```yaml
reverse_proxy:
  hls_cache:
    cache_path: "/tmp/tuliprox/cache/hls"
    strip:
      mode: "segments"
      value: 0
    cache_duration: 300
    cache_bytes: "10GB"
    cache_bytes_per_session: "512MB"
    max_segments_prefetch: 6
    max_concurrent_segment_fetches_per_session: 2
    max_concurrent_segment_fetches_global: 64
    origin_manifest_timeout_ms: 3000
    origin_segment_timeout_ms: 10000
    session_idle_timeout: 300
    segment_repair:
      max_level: "off"
      apply_to_first_segments: 1
      max_parallel_repairs: 1
      postprocess_timeout_ms: 2000
      corrupt_segment_watchdog:
        mode: "off"
        max_parallel_jobs: 1
```

### HLS Cache Parameter Details

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `cache_path` | Path | `/tmp/tuliprox/cache/hls` | Root directory for future HLS segment and MAP cache objects. |
| `strip.mode` | String | `segments` | Interprets `strip.value` as either a segment count (`segments`) or accumulated `#EXTINF` duration (`seconds`). |
| `strip.value` | Int | `0` | Initial tail holdback for the first rendered HLS view. |
| `cache_duration` | Seconds | `300` | Retention baseline for unprotected HLS cache objects. |
| `cache_bytes` | Byte size | `10GB` | Global HLS cache byte budget. |
| `cache_bytes_per_session` | Byte size | `512MB` | Per-session HLS cache byte budget. |
| `max_segments_prefetch` | Int | `6` | Maximum session-local segment prefetch queue depth. |
| `max_concurrent_segment_fetches_per_session` | Int | `2` | Maximum concurrent future segment fetches for one HLS session. |
| `max_concurrent_segment_fetches_global` | Int | `64` | Maximum concurrent future segment fetches across all HLS sessions. |
| `origin_manifest_timeout_ms` | Milliseconds | `3000` | Timeout for future Origin manifest fetches. |
| `origin_segment_timeout_ms` | Milliseconds | `10000` | Timeout for future Origin segment fetches. |
| `session_idle_timeout` | Seconds | `300` | Idle timeout before a future HLS cache session may be collected. |
| `segment_repair.max_level` | String | `off` | Maximum repair level allowed by the codec-aware MPEG-TS segment repair policy (`off`, `low`, `medium`, `high`). |
| `segment_repair.apply_to_first_segments` | Int | `1` | Number of visible TS objects checked per access-lease activation. |
| `segment_repair.max_parallel_repairs` | Int | `1` | Maximum concurrent repair jobs. Must not exceed `max_segments_prefetch` when repair is enabled. |
| `segment_repair.postprocess_timeout_ms` | Milliseconds | `2000` | Shared timeout for the complete segment post-processing chain, including repair and watchdog work. |
| `segment_repair.corrupt_segment_watchdog.mode` | String | `off` | Optional watchdog for residual TS packet-corrupt warnings after regular repair (`off`, `detect_only`, `sanitize`, `diagnostic`). |
| `segment_repair.corrupt_segment_watchdog.max_parallel_jobs` | Int | `1` | Maximum concurrent watchdog sanitize jobs. |

Supported byte-size units:

* `B`
* `KB`, `MB`, `GB`, `TB` as decimal 1000-based units
* `KiB`, `MiB`, `GiB`, `TiB` as binary 1024-based units
* no suffix means bytes

Important boundaries:

* `reverse_proxy.hls_cache` only prepares the global cache engine. A target must also set
  `options.share_live_streams.hls: true` in `source.yml` before generated HLS live entries use the shared HLS path.
* HLS cache retry behavior is fixed internally and is not user-configurable.
* `reverse_proxy.rewrite_secret` must stay stable. It is used for future HLS `proxy_session_id` values and transient resource IDs.
* `session_idle_timeout` controls HLS cache access-lease validity and idle cleanup. It is independent from
  `reverse_proxy.stream.hls_session_ttl_secs`, which belongs to the non-cache HLS request continuity path.
* This block does not enable legacy resource caching; image/logo/EPG caching remains controlled by `reverse_proxy.cache`.

---

## 3. Rate Limiting (`rate_limit`)

This block implements an IP-based **Token-Bucket** rate limiter.
It protects your Tuliprox instance and upstream providers from DDoS attacks, malfunctioning scrapers,
or aggressive players by restricting the frequency of incoming HTTP requests.

```yaml
reverse_proxy:
  rate_limit:
    enabled: true
    period_millis: 500
    burst_size: 10
```

### Rate Limit Parameter Details

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `enabled` | Bool | `false` | Global switch for the rate limiting engine. |
| `period_millis` | Int | `500` | The refill rate. Defines how many milliseconds it takes to replenish exactly one request token. |
| `burst_size` | Int | `10` | The bucket capacity. Allows a client to send this many requests instantly before the rate limit kicks in. |

### Technical Background

* **Mechanism:** A client starts with a full "bucket" of `burst_size` tokens. Every request consumes one token.
  Once empty, the client must wait `period_millis` for a new token to be generated.
* **IP-Detection:** Tuliprox identifies clients by their IP address.
  If you are running Tuliprox behind a proxy (Nginx, Traefik), ensure headers like `X-Forwarded-For` or `X-Real-IP` are passed correctly.
* **Behavior:** When a client exceeds the limit, Tuliprox returns an `HTTP 429 (Too Many Requests)` status,
  protecting your CPU and provider bandwidth.

---

This block controls which HTTP headers Tuliprox removes before forwarding a client request to the upstream provider.
Stripping these headers is essential to prevent the provider from detecting proxy usage, internal IP addresses,
or specific player fingerprints.

```yaml
reverse_proxy:
  disabled_header:
    referer_header: true    # Removes 'Referer' (prevents leaking your Tuliprox URL/Domain)
    x_header: true          # Removes all 'X-*' headers (e.g., X-Forwarded-For, X-Real-IP)
    cloudflare_header: true # Removes 'CF-*' headers (hides Cloudflare origin details)
    custom_header:          # List of additional specific headers to be dropped
      - "X-Powered-By"
      - "my-custom-tracker"
```

### Header Stripping Parameter Details

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `referer_header` | Bool | `false` | Suppresses the source of the request. Prevents your Tuliprox instance from being logged at the provider. |
| `x_header` | Bool | `false` | **Critical:** Wildcard-strips all headers starting with `X-`. These are the most common indicators used for proxy detection. |
| `cloudflare_header` | Bool | `false` | Removes Cloudflare-specific headers. Essential if Tuliprox itself is running behind a Cloudflare proxy. |
| `custom_header` | List | `[]` | Manual blacklist for headers not covered by the automatic toggles above (e.g., vendor-specific trackers). |

> **Security Note:** Many providers analyze headers for "restreaming" patterns.
> Combining `x_header: true` with a neutral `user_agent` in your `source.yml` provides the best protection against account flags.

## 5. Resource Retries (`resource_retry`)

This block defines the retry behavior when Tuliprox proxies static resources (logos, EPG images).
It ensures transient network issues or temporary provider timeouts don't result in broken images for your clients.

```yaml
reverse_proxy:
  resource_retry:
    max_attempts: 3
    backoff_millis: 250
    backoff_multiplier: 1.5
    failover_redirect_patterns:
      - "service-abuse"
```

### Resource Retry Parameter Details

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `max_attempts` | Int (u8) | `3` | Maximum number of download tries before giving up. Minimum is `1`. |
| `backoff_millis` | Duration | `250` | Initial wait time (ms) after the first failure. |
| `backoff_multiplier` | Float | `1.5` | Factor by which the delay grows. `> 1.0` creates an exponential backoff. |
| `failover_redirect_patterns` | List | `[]` | Regex patterns to identify "Abuse" or "Blocked" redirect URLs from providers. |

### Technical Background

* **Exponential Backoff:** The wait time for each attempt is calculated as:
  $$ \text{delay} = \text{backoff\_millis} \times (\text{backoff\_multiplier}^{\text{attempt}-1}) $$
* **Failover Logic:** Providers sometimes redirect blocked requests (HTTP 302) to a "service-abuse.png" image.
  If a redirect URL matches a pattern in `failover_redirect_patterns`, Tuliprox treats it as a hard failure
  and triggers a retry instead of serving the abuse image.
* **Smart Handling:** If an upstream server sends a `Retry-After` header, Tuliprox prioritizes that value
  over the local backoff calculation.

---

## 6. GeoIP Resolution (`geoip`)

This block enables local IP-to-Country mapping.
It allows the Tuliprox Web UI to display country flags in the **"Active Streams"** tab,
providing immediate visual feedback on client locations.

```yaml
reverse_proxy:
  geoip:
    enabled: true
    url: "https://raw.githubusercontent.com/sapics/ip-location-db/refs/heads/main/asn-country/asn-country-ipv4.csv"
```

### GeoIP Parameter Details

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `enabled` | Bool | `false` | Global switch for GeoIP resolution. |
| `url` | String | *(Optional)* | Source URL for the GeoIP CSV database. |

### Technical Background

* **Data Format:** Tuliprox requires a CSV format with exactly three columns:
  `range_start, range_end, country_code`
  *Example:* `1.0.0.0, 1.0.0.255, AU`
* **Performance:** The database is loaded into a high-speed memory-mapped structure to ensure that resolving client locations
  adds zero latency to stream processing.
* **Automation:** To keep the data accurate, use the `GeoIpUpdate` task type within the `schedules` block.
  This periodically downloads and rebuilds the local binary lookup file.
* **Privacy:** All resolution happens locally on your server; no client IPs are ever sent to external third-party APIs for location lookups.

The CSV file must have exactly 3 columns: `range_start,range_end,country_code`.
(The DB is periodically updated via the `schedules` block using the `GeoIpUpdate` task type).

---

## 7. Stream History (`stream_history`)

This block enables persistent stream lifecycle telemetry. Tuliprox writes daily binary history files containing
successful connects, startup failures, disconnect reasons, provider-open failures, reconnect counts, latency
signals, and stable stream identity fields.

When the same channel exists multiple times across different providers, stream history gives Tuliprox the raw
event-level view for each variant. It records which variant failed, how it failed, how often it reconnects, and
whether the problem happened during startup or while streaming.

**User impact:**

* Gives you a reliable answer to questions like "Which stream failed?", "Was this a provider abort or a capacity problem?",  
  and "How often does this stream reconnect?"
* Builds the raw data foundation for later QoS analysis and failover optimization.
* Adds asynchronous background disk writes, but does not put synchronous work into the live streaming hotpath.

```yaml
reverse_proxy:
  stream_history:
    stream_history_enabled: true
    stream_history_batch_size: 128
    stream_history_retention_days: 30
    stream_history_directory: ./stream_history
```

### Stream History Parameters

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `stream_history_enabled` | Bool | `false` | Master switch for stream telemetry. If disabled, no stream history files are written. |
| `stream_history_batch_size` | Int | `128` | Number of records buffered before the writer flushes a block to disk. Higher values reduce write frequency; lower values make new records visible sooner. |
| `stream_history_retention_days` | Int | `14` | Number of UTC day partitions retained before old history files are deleted. |
| `stream_history_directory` | String | `stream_history` under `storage_dir` | Directory for daily stream history files. Relative paths are resolved against `storage_dir`. |

### Technical Background

* Stream history records are written asynchronously in append-friendly daily files.
* Recorded event types include:
  * successful connect
  * startup failure (`connect_failed`)
  * disconnect
* Recorded QoS metadata includes:
  * disconnect reason
  * startup failure reason
  * failure stage
  * provider error class / HTTP status
  * reconnect counts
  * first-byte latency
  * stream identity fields for later aggregation

---

## 8. QoS Aggregation (`qos_aggregation`)

This block enables the periodic QoS aggregation worker. It reads stream history in the background and builds
compact per-stream QoS snapshots that summarize recent reliability.

In practice, QoS turns raw stream history into a compact health view for each channel variant. This makes it
possible to compare equivalent variants of the same channel across providers, rank them by reliability, and use
that information for channel selection and failover decisions.

**User impact:**

* Lets you see a condensed reliability view without manually scanning raw history files.
* Prepares the data that the later failover feature can use to prioritize the most reliable stream/provider candidates.
* Keeps heavy analysis work out of request handling and out of the streaming hotpath.

```yaml
reverse_proxy:
  stream_history:
    stream_history_enabled: true
  qos_aggregation:
    enabled: true
    interval_secs: 300
```

### QoS Aggregation Parameters

| Parameter | Type | Default | Technical Impact |
| :--- | :--- | :--- | :--- |
| `enabled` | Bool | `false` | Enables the background QoS worker. Only effective if `stream_history.stream_history_enabled` is also `true`. |
| `interval_secs` | Int | `300` | Polling interval for the aggregation loop. Lower values update snapshots faster but increase background disk and CPU work. |

### Technical Background

* The worker reads raw stream history by UTC day and stores snapshots in dedicated B+Tree databases.
* Snapshots are keyed by stable stream identity and contain rolling `24h`, `7d`, and `30d` windows.
* QoS data is persisted locally, so it survives restarts and can later be consumed by the failover feature without rescanning all history every time.
* If stream history is disabled, QoS aggregation is automatically disabled during config preparation.

---

 

## Additional Information

### Session TTLs for HLS (`.m3u8`) & Catchup

HLS streams do not consist of an endless TCP pipe. Instead, the player downloads small `.ts` segments every few seconds (e.g., `seg1.ts`, `seg2.ts`).

If Tuliprox released and re-acquired the provider slot for every single segment,
providers would block the account for "Account Hopping" or spam. Tuliprox simulates a continuous session:

* `hls_session_ttl_secs: 15`: After a `.ts` segment finishes downloading, the physical slot to the provider is closed,
  but the "Virtual Slot" for this specific user remains reserved for 15 seconds. No other user can steal this slot
  during this window. Channel switches from the same client can immediately take over the reservation.
* The same principle applies to Archive/Catchup TV (`catchup_session_ttl_secs: 45`),
  which shares the same fragmentation and seeking issues.

---

### Archive Proxy Behavior & Live Playback Invariant

When Tuliprox operates as a reverse proxy, it can securely proxy upstream archive/catchup requests.

* **Live Playback Invariant:** A standard live stream request (e.g., `/m3u-stream/live/user/password/1234.m3u8`) **always** starts  
  current live playback. Normal live requests never activate archive mode, even if arbitrary query parameters are added by the player.
* Archive mode is only activated through a dedicated catchup endpoint (such as the generated Tuliprox catchup URLs) or a signed marker  
  generated by Tuliprox itself.
* Live and archive requests are completely isolated and never share the same session key.

---

### Shared Live Streams

Tuliprox can share a live stream (`share_live_streams.mpeg_ts: true` in the target options of `source.yml`).
If 5 users watch the same Live-TV channel, Tuliprox pulls the stream only 1x from the provider and multicasts the bytes locally to 5 clients.

To ensure a user who tunes in 10 seconds later doesn't get player errors due to missing I-Frames/Keyframes,
Tuliprox continuously keeps the last X Megabytes (`shared_burst_buffer_mb`, default `12`) in RAM.
It fires this burst buffer at new subscribers so their decoders can instantly synchronize.

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### The "VLC Seek Problem" & Grace Periods

When a user fast-forwards or rewinds a VOD, the player calculates the new byte offset, drops the old TCP connection,
and immediately fires a new HTTP GET request (with a `Range` header) to Tuliprox.

**The Problem:** It takes milliseconds to seconds for the upstream provider to realize the old connection is dead.
If you have a `max_connections: 1` limit at the provider, they will view this new seek-request as a *second concurrent stream*
and reject it with an HTTP 509 (Bandwidth Exceeded) or HTTP 401 error.

**The Tuliprox Solution:**

* `grace_period_millis: 2000`: Tuliprox grants the user a temporary over-allocation (Grace) for exactly this duration.
* `grace_period_hold_stream: true`: Tuliprox artificially holds back the video data to the client,
  waiting for the grace check to finish, so it doesn't trigger the provider prematurely.
* After the milliseconds expire, Tuliprox checks internally: Is the old connection truly gone now? <br>
  If Yes ➔ Data flows.<br>
  If No ➔ The new connection is hard-killed (serving the `user_connections_exhausted.ts` video)
  because the user is actually illegally watching twice.
* `grace_period_timeout_secs: 4`: A hard timeout limit for overlapping "ghost sessions" to expire.