## Problem
The blocklist URL validation at create/update time has a TOCTOU (time-of-check-to-time-of-use) window.
An attacker can perform a DNS-rebinding attack where:
1. User adds blocklist URL pointing to attacker.com
2. At create time, attacker.com resolves to a public IP → validation passes
3. Later, when fetching, attacker.com resolves to 192.168.1.1 (internal network)
4. HTTP client connects to the private IP, potentially accessing internal services
## Solution
Add runtime destination IP validation at connection time via a custom socket factory:
- Created 'dns_validated_connector.py' with create_dns_validated_socket_factory() that validates
all resolved IPs before socket creation
- HTTP session now uses the validated socket factory, protecting all blocklist imports globally
- Rejects connections to RFC 1918 private ranges, loopback, link-local, ULA, multicast, and
reserved addresses (IPv4 and IPv6)
- Added comprehensive test coverage with 13 test cases
## Changes
- backend/app/services/dns_validated_connector.py: Custom socket factory with IP validation
- backend/app/startup.py: Use DNS-validated socket factory in HTTP session creation
- backend/app/utils/ip_utils.py: Updated docstring explaining runtime validation
- backend/app/services/blocklist_downloader.py: Updated module docstring
- backend/app/services/blocklist_service.py: Updated docstrings explaining two-layer protection
- backend/tests/test_services/test_dns_validated_connector.py: Test suite for socket factory
- Docs/Architekture.md: Added detailed section on DNS-rebinding protection
## Testing
- All 13 DNS validation tests pass
- All blocklist downloader tests pass (unaffected by changes)
- Linting: ruff, mypy pass with --strict
- Test coverage: 90% line coverage on dns_validated_connector.py
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
- Created StartupDAG class to orchestrate startup stages with explicit dependencies
- Defined 6 startup stages: WORKER_MODE → DATABASE → GEO_CACHE → HTTP_SESSION → SCHEDULER → TASKS
- Each stage has prerequisites, error handling, and rollback support
- Refactored startup_shared_resources() to use the DAG
- Added StartupContext for resource tracking and failure management
- Partial failures automatically roll back all completed resources in reverse order
- Added health checks to verify all resources initialized successfully
- Comprehensive test coverage: 15 DAG unit tests + 3 integration tests + 6 existing tests
- Documented startup DAG in Architekture.md with detailed stage descriptions and failure modes
This replaces implicit ordering with explicit dependency tracking, making lifecycle
changes safe and failure modes predictable. Hidden order dependencies no longer exist.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Add automatic cleanup of stale geolocation cache entries to prevent
unbounded database growth. Resolves the issue where unique IP addresses
accumulated indefinitely in the geo_cache table, degrading query performance.
## Changes
### Database Schema (Migration 3)
- Add 'last_seen' column to geo_cache table tracking last reference time
- Existing entries default to current timestamp
### Repository Layer (geo_cache_repo.py)
- Update upsert_entry() to set/refresh last_seen on insert/update
- Update upsert_neg_entry() to set/refresh last_seen on negative cache hits
- Update bulk_upsert_entries() to set/refresh last_seen in batch operations
- Add delete_stale_entries(db, cutoff_iso) -> int for purging old entries
### Background Task (geo_cache_cleanup.py)
- New APScheduler task that runs nightly (24-hour interval)
- Calculates cutoff as 90 days ago from current time (UTC)
- Deletes all entries with last_seen older than cutoff
- Logs operation results (info when deleted > 0, debug when 0 deleted)
- Configurable retention period via GEO_CACHE_RETENTION_DAYS constant
### Application Startup (startup.py)
- Register geo_cache_cleanup task in scheduler during app startup
- Placed after geo_cache_flush in task registration order
### Tests
- Add delete_stale_entries test cases covering:
* Removal of old entries beyond cutoff
* No deletion when all entries are recent
* Empty table edge case
- Update existing test fixtures to include last_seen column
- Add full test suite for cleanup task registration and execution
### Documentation
- Architekture.md: Document cleanup task, update schema/diagram
- Backend-Development.md: Add retention policy documentation
## Behavior
When an IP is accessed, its last_seen is refreshed. After 90 days of no
access, an IP is purged by the nightly cleanup. On next encounter, the IP
is re-resolved from MaxMind MMDB or ip-api.com (if configured).
This is acceptable because:
1. Stale geolocation data may become inaccurate over time
2. Re-resolution cost is minimal compared to unbounded storage growth
3. Active IPs maintain fresh data through their last_seen updates
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Make MaxMind GeoLite2-Country MMDB the primary IP resolver (local, encrypted)
and demote ip-api.com to optional fallback only (disabled by default).
Changes:
- Add geoip_allow_http_fallback config flag (default False) to Settings
- Refactor GeoCache.lookup() and lookup_batch() to try MMDB first
- Update startup.py to pass config flag and log security warning when HTTP enabled
- Update all 49 tests to reflect new MMDB-primary strategy
- Add comprehensive geoip configuration section to Backend-Development.md
- Update Architekture.md to show MMDB + optional HTTP in system dependencies
- Update .env.example with BANGUI_GEOIP_DB_PATH and HTTP fallback flag
Security impact:
- 99% of IP addresses (successful MMDB lookups) now stay local, encrypted
- HTTP-only IPs are cached for 5 minutes to minimize external calls
- Operators must explicitly enable HTTP fallback (security-conscious default)
- GDPR/CCPA compliance: no PII sent over unencrypted networks by default
Fixes TASK-030: Resolved plaintext IP transmission to ip-api.com
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
- Add _check_single_worker_mode() to startup.py that detects and rejects
multi-worker configurations, raising a clear RuntimeError with instructions
- Set BANGUI_WORKERS=1 as default in Dockerfile.backend
- Document single-worker requirement in compose.prod.yml
- Add 'Deployment Constraints' section to Architekture.md explaining why
single-worker mode is required and detailing future multi-worker support
- Add '9.1 Background Tasks and Scheduler Architecture' section to
Backend-Development.md documenting task structure and single-worker requirement
- Add comprehensive test suite (test_startup.py) covering all scenarios:
allows single worker, rejects multi-worker, validates config format,
and verifies informative error messages
This fix addresses TASK-002 which identified that in-process APScheduler is
unsafe in multi-worker deployments due to each worker creating independent
scheduler instances, causing duplicate background job execution.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Create GeoCache class with all mutable state as instance attributes:
- _cache, _neg_cache, _dirty, _geoip_reader, _geoip_initialized, _cache_lock
- All public methods: lookup(), lookup_batch(), lookup_cached_only(), flush_dirty(), load_from_db(), clear(), etc.
Initialization & Dependency Injection:
- Instantiate GeoCache in startup.py and store on app.state.geo_cache
- Add get_geo_cache() dependency function in dependencies.py
- Inject into routes and tasks via FastAPI's dependency system
Backward Compatibility:
- Maintain module-level functions in geo_service.py as deprecated wrappers
- All old callers continue to work through _default_geo_cache instance
- Remove test-escape-hatch functions (clear_cache, clear_neg_cache moved to methods)
Background Tasks:
- Update geo_cache_flush.py and geo_re_resolve.py to receive GeoCache instance
- Tasks now operate on injected instance rather than module globals
Tests:
- Refactor test_geo_service.py with geo_cache fixture providing fresh instances
- Update patch paths to target GeoCache methods correctly
- Fix internal state assertions to access instance attributes
Documentation:
- Update Architekture.md to document GeoCache as managed stateful service
- Describe cache lifecycle (load on startup, flush periodically, re-resolve stale)
- Note process-local limitations for multi-worker deployments
Fixes violation of Single Responsibility Principle: module no longer owns both
lookup logic and cache lifecycle management. Cache is now a first-class
injectable service with transparent lifecycle.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
