feat(dns-instrument): capture redirect chain hops via onHeadersReceived

[vringar]

Summary

• Move DNS instrumentation from onCompleted to onHeadersReceived to capture all redirect chain hops
• Add redirect_url column to dns_responses schema (SQL, Parquet, TypeScript)
• Do NOT modify shared PendingResponse class — DNS works independently
• Rename onCompleteDnsHandler to onHeadersReceivedDnsHandler
• Test verifies captured row content (URLs), not just count

Supersedes #1021. Incorporates fixes from adversarial review (VDD methodology).

VDD Review History

• Round 1: Found PendingResponse pollution breaking HTTP instrument, non-unique request_id, count-only test
• Round 2: Fixed PendingResponse (untouched), added redirect_url. Found parquet_schema desync, test_values missing
• Round 3: All findings fixed. Parquet synced, test asserts content.
• Final verdict: Begrudgingly Adequate (converged)

Test plan

• test_dns_instrument.py verifies redirect_url content per hop
• Schema consistency: schema.sql, parquet_schema.py, schema.ts all have redirect_url
• pre-commit run --all-files passes

[Copilot]

Pull request overview

This PR updates the DNS instrumentation to log at webRequest.onHeadersReceived instead of onCompleted, enabling capture of DNS records across redirect chains, and synchronizes storage schemas to persist the associated URL per hop.

Changes:

• Switch DNS logging trigger to onHeadersReceived and record the per-event URL as redirect_url.
• Add redirect_url to the dns_responses schema across SQLite (SQL), Parquet (PyArrow), and the WebExtension TypeScript types.
• Strengthen the DNS instrumentation test to assert that recorded rows contain URL content (not just row count).

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
Extension/src/background/dns-instrument.ts	Moves DNS collection to onHeadersReceived and stores redirect_url = details.url.
Extension/src/types/browser-web-request-event-details.ts	Adds a typed onHeadersReceived details interface with optional ip.
Extension/src/schema.ts	Adds optional redirect_url to the DnsResolved record type.
openwpm/storage/schema.sql	Adds redirect_url column to dns_responses.
openwpm/storage/parquet_schema.py	Adds redirect_url (and syncs used_address) for dns_responses Parquet schema.
test/test_dns_instrument.py	Adds assertions around redirect_url presence/content.
test/storage/test_values.py	Updates generated test values for dns_responses to include redirect_url/used_address.
.gitignore	Ignores local Crosslink/Claude generated state files and directories.

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[Copilot]

Because the test indexes into results[0] from an unfiltered SELECT * FROM dns_responses (no ORDER BY), the new behavior of logging on onHeadersReceived (redirect hops + potentially additional requests) can make row ordering nondeterministic and the assertions flaky. Consider filtering the query to the expected request/hostname and/or adding an explicit ORDER BY (e.g., id or time_stamp) before selecting the row(s) to assert against.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.16%. Comparing base (58218c7) to head (087f858).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1158   +/-   ##
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  Coverage   62.16%   62.16%           
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  Files          40       40           
  Lines        3898     3898           
=======================================
  Hits         2423     2423           
  Misses       1475     1475           

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