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Implements the UrlValidator sketch agreed on issue a2aproject#1023: a core validator parses and resolves a URL, runs composable UrlValidationRule objects (RequireScheme, BlockPrivateNetworks with allow_hosts/allow_cidrs), and returns a ResolvedUrl that carries the addresses the host resolved to, so callers can pin connections to a validated address and guard against DNS rebinding. Domain wrappers: - PushNotificationUrlValidator: validate_push_notification_url now delegates to the composable stack; its boolean, fail-closed contract is unchanged (all existing SSRF tests pass unmodified). - AgentCardUrlValidator: new, validating agent card URLs (http/https, public addresses by default, private networks opt-in). Rules and the resolver are individually injectable so deployments can compose custom policies. Issue a2aproject#1023 scopes this to the validator as the foundation for a2aproject#975 and a2aproject#786. Refs a2aproject#1023 Signed-off-by: andy <linux2011@qq.com>
🧪 Code Coverage (vs
|
| Base | PR | Delta | |
|---|---|---|---|
| src/a2a/server/cluster/database_event_stream.py | 92.86% | 96.94% | 🟢 +4.08% |
| src/a2a/utils/push_url_validator.py | 87.80% | 100.00% | 🟢 +12.20% |
| src/a2a/utils/url_validation.py (new) | — | 99.05% | — |
| Total | 93.10% | 93.23% | 🟢 +0.13% |
Generated by coverage-comment.yml
Linux2010
marked this pull request as draft
October 10, 2026 15:09
Linux2010
marked this pull request as ready for review
October 11, 2026 01:04
Self-review follow-ups for the a2aproject#1023 draft: - expose the address union as public UrlAddress instead of a private alias (it appears in the public ResolvedUrl annotation); - match BlockPrivateNetworks allow_hosts case-insensitively: urlparse lowercases parsed hostnames, so configured exemptions must be normalized too; - deduplicate resolved addresses while preserving resolver order (getaddrinfo repeats addresses across CNAME chains and record families). Signed-off-by: andy <linux2011@qq.com>
…n_url PushNotificationUrlValidator already catches InvalidUrlError and logs, so the wrapper's own try/except was unreachable dead code and showed up as a -25% coverage regression on the per-file report (spotted by the coverage bot on this PR). The wrapper is now a single-line delegation to the domain wrapper, which owns the logging; a dedicated test module locks the boolean, fail-closed contract directly. Signed-off-by: andy <linux2011@qq.com>
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Description
Implements the
UrlValidatorsketch from #1023 as the shared, composable URL-screening foundation for both SSRF surfaces called out there (agent card URLs and push-notification webhooks):UrlValidator: parses and (optionally) resolves a URL, runs composableUrlValidationRuleobjects in order, and returns aResolvedUrlcarrying the addresses the host resolved to — so callers can pin connections to a validated address (DNS-rebinding protection).RequireSchemeandBlockPrivateNetworks(withallow_hosts/allow_cidrsexemptions for deployments that legitimately use private networks). Custom rules are plainUrlValidationRulesubclasses.PushNotificationUrlValidator—validate_push_notification_urlnow delegates to the composable stack; its boolean, fail-closed contract is unchanged (all existing SSRF tests pass unmodified).AgentCardUrlValidator— new; validates agent card URLs (http/https on public addresses by default, private networks opt-in).Scope note: per #1023 this lands the validator as the foundation; wiring the agent card validator into the client resolution path and a connection-pinning transport are follow-ups (the resolved addresses are returned precisely to enable the latter).
Notes for reviewers:
Rules and the resolver are injectable, which keeps tests deterministic without touching
loop.getaddrinfo.Cancellation is unaffected:
asyncio.CancelledErrorderives fromBaseException, so guards onExceptionnever swallow cancellation.Follow the CONTRIBUTING Guide
PR title follows Conventional Commits (
feat:→ SemVer minor)Tests and linter pass
Appropriate docs were updated (module/ABC docstrings state the contract)
Refs #1023 🦕
Validation
UrlValidatorrejects non-http(s) schemes and hosts resolving to non-public addresses;validate_push_notification_urlkeeps its exact accept/reject behavior.tests/utils/test_url_validation.py; full suite2300 passed, coverage93%(gate 88%).AgentCardUrlValidatorinto the client resolution path (proposed follow-up, happy to add on request).Prepared with AI assistance (WorkBuddy); reviewed and verified by Linux2010