internal/

Package alerts is the producer-facing seam for security alerting.

Package apicontract is the durable enforcement core of the Culvert OpenAPI program.

Package audit is the admin-action audit trail engine: a bounded in-memory ring (the newest MaxRing entries), optional append-only JSONL persistence with rotation, paginated/time-filtered reads over both, and the Data-Plane → Control-Plane push queue.

Package autoexclude is the adaptive decryption-exclusion cache: a bounded, TTL-bounded, in-memory learned set of hosts that could not be SSL-inspected, so that subsequent CONNECTs to them can fail open (bypass decryption) instead of breaking.

Package backupcrypt is the D1.4 backup-envelope cryptography leaf: optional AES-256-GCM encryption of the compressed tar.gz backup blob, with the fixed 43-byte header bound to the ciphertext via AAD so any header tampering — including a KDF iteration-count downgrade — fails authentication.

Package bandwidth is the per-node-group bandwidth/QoS policy engine: named policies with label selectors, priority-based matching (F10 overlap detection), token-bucket rate limiting, and atomic JSON persistence.

Package blocklist is the host blocklist engine: O(labels) exact/wildcard matching with a never-block exceptions list, block/allow modes, sidecar persistence (.mode/.manual/.exceptions/.sources), per-feed attribution, and hosts-format line normalization.

Package blocklistfeed is the remote blocklist syncer: it periodically downloads one or more remote blocklists (one domain per line, '#' comments allowed) and merges new entries into the live blocklist without removing manually-added entries.

Package blockpage owns the corporate "Access Denied" block page: the default HTML template, the runtime-mutable override, and the 403 response writer.

Package bootstrap generates the one-click DP-node deployment artifacts: the shell install script and the docker-compose.yml that the Control Plane serves against a single-use enrollment token.

Package ca implements Culvert's SSL-inspection Root CA — the MITM trust core (ADR-0002 extraction; engine was ca.go in package main).

Package catdb is Layer 2 of the two-tier URL categorisation engine — the community category store.

Package catgroup is the named category-group engine: bundles of URL categories (e.g.

Package catoverride is the admin-owned category-override engine for the signed SaaS URL-category feed (F3a-1, per roadmap/FEEDS-DISTRIBUTION-F3-DESIGN.md §7.2).

Package clamav implements a ClamAV CLAMD protocol client (INSTREAM scanning) over Unix domain sockets or TCP, with zero external API dependency.

Package clientclass is the deterministic client classifier: whether a request comes from an interactive browser (eligible for a captive-portal SSO redirect), an opaque CONNECT tunnel (never redirectable), or a non-browser service client.

Package configver implements the numbered config-version snapshot store (ADR-0002 extraction; engine was the store half of configversion.go in package main).

Package connlimit provides per-IP connection limiting.

Package decryptobs is the bounded-enum vocabulary for Culvert's decryption- observability model (ADR-0011).

Package decryptprofile is the named SSL-decryption-profile engine: a PAN-OS-style "how to decrypt" object that policy rules reference by name to control HOW an inspected (SSLAction=Inspect) tunnel is decrypted — whether to inspect natively as HTTP/2, the upstream server-certificate-verification posture, the unsupported-TLS failure posture, the TLS version floor/cap, and the per-stream inactivity bound.

Package feedsync is the UT1 URL-category feed syncer: it periodically downloads the UT1 Capitole blacklist tarball (via the NethServer mirror), extracts the categories in the ingest map, and bulk-writes them into the community URL-category database (internal/catdb).

Package fileblock is the file-type blocking engine: an extension/MIME/ Content-Disposition blocklist (FileBlocker) and named file-type profiles (FileProfileStore, in fileprofile.go).

Package filemagic does magic-byte detection for archive identification and polyglot detection — examining the first bytes of a response body to catch archives disguised as safe types and Content-Type/content mismatches.

Package fileutil provides durable filesystem helpers shared by package main and internal/* packages (ADR-0003).

Package geoip is the GeoIP country-lookup engine: a local MaxMind GeoLite2 (.mmdb) reader with an in-memory IP→country cache.

Package halease is the HA fencing-lease primitive (ADR-0005 S1): a single cluster-wide lease with a strictly-monotonic epoch (the fencing token), arbitrated by a strongly-consistent backend.

Package hashcache provides a size-bounded, TTL-evicting cache of security scan results keyed on the SHA-256 digest of scanned content.

Package hostutil provides pure host-string normalization helpers shared across the proxy (policy matching, category lookups, scan/bypass keys).

Package lockout provides the login account-lockout limiter and the admin-API rate limiter.

Package logstore is the Badger-backed, time-ordered persistent request-log history engine.

Package nodegroup is the node-group definition store: named collections of Data-Plane nodes matched by label selectors (geo-aware grouping, tiered routing, policy scoping), with atomic JSON persistence.

Package obs is the shared logging facade for internal/* packages (ADR-0003).

Package ocsp is the OCSP revocation-checking engine for upstream TLS certificates: a TTL'd verdict cache plus the responder query pipeline behind a tls.Config VerifyPeerCertificate callback.

Package otlp exports metrics and request spans to any OpenTelemetry Collector via the OTLP/HTTP JSON protocol (POST /v1/metrics, /v1/traces).

Package pac is the PAC (proxy auto-config) engine: the persisted PAC configuration store and the FindProxyForURL generator.

Package plugin is the Culvert middleware plugin API: the Middleware contract, the process-wide plugin chain, and the panic-safe dispatch the proxy hot path calls.

Package redaction is the data-governance engine for support bundles (REDACTION-MODEL.md, ADR-0009).

Package reqlog is the request-log engine: a bounded in-memory ring (the newest MaxRing entries), an optional persistent JSONL layer with rotation and a count-once-log-first write-error contract, a bounded newest-first read over the persistent file with a short-TTL shared-parse cache, and the status→level mapping.

Package rewrite owns per-host HTTP header rewrite rules: the rule DTO, the ordered active rule set, and the request/response header mutators.

Package saasfeed is the SaaS category feed syncer: it periodically fetches a curated JSON file of SaaS URL categories (AI, Marketing, Messaging, …) from a remote URL and hands the parsed categories to an injected merge callback.

Package scanexcl holds the admin-managed scan-exclusion store: known-good SHA-256 content hashes and hostnames that bypass all body scanning.

Package scanner is the DPI content scanner: a set of pre-compiled regex signatures applied to HTTP response bodies flowing through SSL-Inspect tunnels, with a per-host bypass list and atomic persistence.

Package sealbox is the recipient-public-key sealing leaf for support-bundle export (M4 E2E).

Package secret is the compiler-enforced containment boundary for key-encryption-key (KEK) material and key-at-rest wrapping, per docs/adr/0007-secret-containment-boundary.md and roadmap/SECRET-CONTAINMENT-PLAN.md.

Package secscan is the security-scan orchestrator: it ties ClamAV, YARA, the threat feed, the hash cache, and the admin hash allowlist into the single pipeline the proxy hot path calls.

Package session implements Culvert's HMAC-SHA256-signed session tokens and the revocation machinery behind them (ADR-0002 extraction; engine was session.go in package main).

Package sse is the Server-Sent-Events client hub: registration under a connection cap, fan-out broadcast with slow-client eviction, and the hub-level observability counters.

Package sslbypass is the SSL-inspection bypass matcher: a runtime-managed list of host patterns (FQDN globs via hostutil.MatchFQDN semantics, or "~"-prefixed regexes) that must always bypass SSL inspection regardless of what the PBAC policy says, with pre-compiled matching and JSON file persistence.

Package ssrf is the SSRF (server-side request forgery) guard: the private/internal CIDR table, host resolution checks with a short-TTL DNS cache, and the connect-time dialer control that closes the DNS-rebinding TOCTOU window.

Package support is the support-bundle engine (SUPPORT-BUNDLE-SPEC.md, COLLECTOR-CONTRACT.md): a plugin registry of small, isolated, budgeted, self-redacting collectors plus a runner that assembles a deterministic, integrity-hashed `csb/1` bundle.

Package supportmetrics implements the M7 scoped support-metric registry (roadmap/M7-proactive-telemetry-plan.md §6).

Package supportupload is the appliance-side client for M6 "Optional secure upload" (docs/support/SECURE-UPLOAD-ARCHITECTURE.md §4): a resumable, SSRF-guarded, chunked, outbound-only HTTPS uploader to a TAC upload gateway.

Package syslog forwards log lines to a remote syslog server over UDP or TCP.

Package threatfeed is the local threat-feed manager: it downloads, persists, and provides instant offline lookups for known-malicious URL/domain lists.

Package totp implements TOTP (RFC 6238) validation using only the standard library: HMAC-SHA1 with a 30-second step, 6-digit output, and ±1 step clock skew.

Package uitls generates the self-signed TLS certificate for the admin UI: baseline loopback SANs, all local interface IPs, the hostname, operator extras (CULVERT_PUBLIC_IP + --ui-san values passed in by the caller), and best-effort cloud public-IP detection via instance metadata.

Package upstream implements parent-proxy chaining with failover and circuit-breaker protection (ADR-0002 extraction; engine was upstream.go in package main).

Package urlcat is the admin-managed URL-category engine: named categories with lowercase host-set indexing for O(labels) membership checks during policy evaluation, JSON file persistence, and the built-in + embedded-SaaS default seed list.

Package urlcatfeed is the producer + trust kernel for the public, signed SaaS URL-category feed distributed from feeds.culvertlabs.com (roadmap/FEEDS-DISTRIBUTION-F0-DESIGN.md).