dnswatcher/TODO.md

Workflow

• branch (from main)
• do the work in Next Step
• move Next Step to the top of Completed Steps
• move the top item of Future Steps into Next Step
• commit (TODO.md changes in the same commit as the work)
• merge to main if the branch is not protected, otherwise open a PR
• push

Status

pre-1.0. No git tags. Core resolver work in flight on feature/resolver (dirty: internal/resolver/resolver_test.go). Local checkout has diverged from origin: origin/main is 8 commits ahead (watcher orchestrator, unified TARGETS) and origin/feature/resolver already contains the full iterative resolver implementation with hermetic mocked tests.

Next Step

Policy scaffold commit: add LICENSE, REPO_POLICIES.md, .editorconfig, .dockerignore, and .gitea/workflows/check.yml, and add the missing fmt-check, docker, and hooks targets to the Makefile. One commit, then confirm make check still passes.

Completed Steps

• 2026-07-07 Adopted scripts-to-rule-them-all: script/ entrypoints, Makefile shims, README Entrypoints section
• 2026-02-20: iterative DNS resolver implemented; tests made hermetic with mocked DNS (origin/feature/resolver, unmerged)
• 2026-02-20: CI actions and go install refs pinned to commit SHAs; Gitea Actions workflow for make check (origin/ci/make-check, unmerged)
• 2026-02-20: watcher monitoring orchestrator merged to main (#8)
• 2026-02-20: DOMAINS/HOSTNAMES unified into single TARGETS config (#11)
• 2026-02-19: TCP port connectivity checker, made concurrent with port validation; gosec G704 SSRF findings fixed without suppression (feature branches, unmerged)
• 2026-02-19: TLS certificate inspector with no-peer-certificates error path and IP SANs (feature branch, unmerged)
• 2026-02-19: gosec SSRF and formatting fixes on main
• 2026-02-19: initial scaffold with per-nameserver DNS monitoring model

Future Steps

Compliance:

• Add README sections required by policy (Description, Getting Started, Rationale, Design, TODO, License, Author) if any are missing
• Pin Dockerfile base images by sha256 and ensure the Docker build runs make check

Branch reconciliation:

• Sync local checkout with origin: local main is 8 commits behind origin/main; local feature/resolver has diverged from origin/feature/resolver, which already implements the resolver
• Merge in-flight branches to main once green: feature/resolver, ci/make-check, feature/portcheck-implementation, feature/tlscheck-implementation

Resolver (plan from untracked TODO.md; largely implemented on origin/feature/resolver, verify each item before closing):

• Add github.com/miekg/dns dependency
• roots.go: hardcoded IANA root server list (a through m, IPv4/IPv6), rootServers() returning ip:53 strings
• query.go: low-level query(ctx, server, name, qtype): UDP with TCP fallback on truncation, RD=0, context respected, 5s per-query timeout, returns raw *dns.Msg
• trace.go: iterative delegation chasing from roots: referral detection (NOERROR, empty answer, NS in authority), glue extraction with bailiwick check, out-of-bailiwick NS resolved with recursion guard, delegation depth limit (20), retry across nameservers on failure, do not chase CNAMEs inside trace
• FindAuthoritativeNameservers: NS set via trace, sorted, FQDN normalized, trailing dot handled; must pass its 9 tests
• QueryNameserver: resolve NS host to IPs, query A/AAAA/CNAME/MX/TXT/ SRV/CAA/NS, build NameserverResponse with status mapping (OK, NXDomain, NoData, Error), documented record formatting, sorted values, lame delegation detection; must pass its 16 tests
• QueryAllNameservers: find NS set for parent domain (public suffix list), query all NS in parallel with bounded concurrency, return map even when all fail, context cancellation; must pass its 4 tests
• LookupNS: thin wrapper over FindAuthoritativeNameservers, sorted, identical results; must pass its 3 tests
• ResolveIPAddresses: collect A/AAAA from all NS, follow CNAME chains with MaxCNAMEDepth, dedupe, sort, NXDOMAIN returns empty slice with nil error; must pass its 9 tests
• All 39 resolver tests pass, make check green, merge to main

Watcher (internal/watcher/watcher.go):

• Scheduling loop in Run(ctx): initial check on startup, separate tickers for DNS/port and TLS intervals, persist state via state.Save() after each cycle, clean shutdown on context cancel
• Domain check: LookupNS, compare to stored state, store silently on first run, notify with old/new NS lists on change
• Hostname check: QueryAllNameservers, compare per-NS records; notify on record changes, NS failure, NS recovery, inconsistency detected, inconsistency resolved, empty response; store silently on first run
• Port check: ResolveIPAddresses, check ports 80 and 443 per IP, notify on open/closed transitions, handle new and disappeared IPs
• TLS check: for each open IP:443, CheckCertificate; notify on expiry warning, certificate change (CN/issuer/SANs), TLS failure/recovery

Port checker (internal/portcheck/portcheck.go):

• Tests against known-open ports and RFC documentation IPs
• CheckPort: net.DialTimeout (5s), context respected; (true, nil) open, (false, nil) closed/timeout/refused, error only for unexpected failures

TLS checker (internal/tlscheck/tlscheck.go):

• Tests against known public HTTPS servers, verify fields populated
• CheckCertificate: tls.Dial to specific IP:443 with hostname as SNI; extract subject CN, issuer CN and org, NotAfter, SANs; error on handshake failure

Notification service (internal/notify/notify.go, Slack/Mattermost/ntfy backends exist):

• Structured notification types: DNS change, port change, TLS expiry, TLS change, NS failure, NS recovery, NS inconsistency
• Per-backend formatting: Slack/Mattermost attachment colors (red failures/expiry, yellow warnings, green recoveries, blue info); ntfy priorities (urgent failures, high warnings, default changes, low recoveries); include hostname, nameserver, old/new values, timestamps

HTTP API handlers:

• Wire *state.State and *watcher.Watcher into handler params
• GET /api/v1/status: full state snapshot as JSON
• GET /api/v1/domains: domain states with NS records and last-checked
• GET /api/v1/hostnames: hostname states with per-NS record data

Infrastructure notes (from untracked TODO.md):

• Module path sneak.berlin/go/dnswatcher differs from the git.eeqj.de remote intentionally; do not "fix" it
• Dependencies: github.com/miekg/dns, golang.org/x/net/publicsuffix
• Resolver tests originally used live DNS against *.dns.sneak.cloud (required records documented in the test file header); origin now has mocked hermetic tests, keep them hermetic