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Do not return a denyError for DNS resolution failures #194

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merged 4 commits into from
Jul 13, 2023

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This PR ensures that the correct errors are surfaced when a DNS resolution error happens during the call to checkIfRequestShouldBeProxied(). Previously, any kind of error, irrespective of the kind, was surfaced as a denyError even if the domain name was allowed by the ACL. This obfuscated the true source of the error and some users were seeing ACL denials that were actually DNS lookup failures.

In the event of an actual ACL denial, pctx.Error will be nil and we should not wrap the returned error with denyError{}. Instead, we now return the raw pctx.Error.

I also added a more granular type assertion for *net.DNSError and included the additional context in the response body.

We had a few tests which were already suitable for checking for this condition. I updated them with the new behavior and response messages.

r? @jjiang-stripe

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Pull Request Test Coverage Report for Build 5536637412

  • 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
  • No unchanged relevant lines lost coverage.
  • Overall coverage increased (+0.1%) to 62.584%

Totals Coverage Status
Change from base Build 5358361284: 0.1%
Covered Lines: 1298
Relevant Lines: 2074

💛 - Coveralls

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nice! checking for *net.DNSError is a nice touch

@cds2-stripe cds2-stripe merged commit 81a59fd into master Jul 13, 2023
4 checks passed
@cds2-stripe cds2-stripe deleted the cds/fix-lookup-denials branch July 13, 2023 13:21
matt-intercom added a commit to intercom/smokescreen that referenced this pull request Jan 4, 2024
* add a custom interface for the resolver instead of forcing *net.Resolver (stripe#187)

* feature/add prometheus metrics (stripe#179)

* STORY-25143 - Add prometheus metrics to smokescreen

* STORY-25143 - Cleanup

* STORY-25143 - Fix tests to compare new metric labels

* STORY-25143 - Host prometheus endpoint on separate port

* STORY-25143 - Use value provided via command line flag

* STORY-25143 - Add prometheus timing metrics

* STORY-25143 - Fix nil map assignment and prometheus metric name sanitisation

* STORY-25143 - Cleanup comments

* STORY-25143 - Remove some repetition + add further unit testing

* STORY-25143 - Document new prometheus features in README + add port flag to prometheus config

* STORY-25143 - Make PR requested changes:
* Don't export metrics list
* Follow project sytlistic choices

* STORY-25143 - Rename only one receiver

* STORY-25143 - Add new `--expose-prometheus-metrics` flag to CLI to toggle exposing prometheus metrics

* Small cleanup of timer metrics

* Fix go module vendoring

* Use ElementsMatch to ignore order

* Just use require

* Move the custom request handler call after the main acl check

* Use local server instead of httpbin (stripe#192)

* Do not return a denyError for DNS resolution failures (stripe#194)

* dont return denial errors for dns resolution failures

* fix test

* move DNSError check into net.Error assertion, extend test

* fix integration test

* add AcceptResponseHandler to modify accepted responses (stripe#196)

* add AcceptResponseHandler to modify accepted responses

* customer->custom

* Update docs to clarify global_deny_list (stripe#197)

* update docs to clarify global_deny_list behavior

* consistent example domain

* be more concise

* Use AcceptResponseHandler in goproxy https CONNECT hook (stripe#199)

* pipe AcceptResponseHandler into new goproxy hook

* update comment

* go mod vendor

* unit test

* use smokescreenctx in acceptresponsehandler

* fix unit tests

* Export SmokescreenContext type (stripe#200)

* export SmokescreenContext type

* also export AclDecision

* ResolvedAddr too

* consistent caps

* Update pkg/smokescreen/smokescreen.go

Co-authored-by: jjiang-stripe <55402658+jjiang-stripe@users.noreply.github.com>

* export Decision

---------

Co-authored-by: jjiang-stripe <55402658+jjiang-stripe@users.noreply.github.com>

* generate new test pki (stripe#206)

* allow listen address specification for prom (stripe#203)

* Bump golang.org/x/net from 0.7.0 to 0.17.0 (stripe#204)

Bumps [golang.org/x/net](https://github.com/golang/net) from 0.7.0 to 0.17.0.
- [Commits](golang/net@v0.7.0...v0.17.0)

---
updated-dependencies:
- dependency-name: golang.org/x/net
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* bump go versions (stripe#207)

* update dependency

* configure addr in smokescreen and add unit test

* use fmt

* try this workaround

* variable name change

* Update docs to disambiguate ACL vs --deny-address behavior (stripe#210)

* update docs to clarify how IP filtering works

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: JulesD <JulesDT@users.noreply.github.com>
Co-authored-by: Josh McConnell <josh.mcconnell465@gmail.com>
Co-authored-by: Kevin Vincent <kevinv@stripe.com>
Co-authored-by: kevinv-stripe <102822342+kevinv-stripe@users.noreply.github.com>
Co-authored-by: Sergey Rud <sergeyrud@stripe.com>
Co-authored-by: cmoresco-stripe <106690468+cmoresco-stripe@users.noreply.github.com>
Co-authored-by: Craig Shannon <cds@stripe.com>
Co-authored-by: jjiang-stripe <55402658+jjiang-stripe@users.noreply.github.com>
Co-authored-by: Timofey Bakunin <36561672+ne-bknn@users.noreply.github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Yuxi Xie <xieyuxi@stripe.com>
Co-authored-by: xieyuxi-stripe <141708814+xieyuxi-stripe@users.noreply.github.com>
matt-intercom pushed a commit to intercom/smokescreen that referenced this pull request Jan 4, 2024
* dont return denial errors for dns resolution failures

* fix test

* move DNSError check into net.Error assertion, extend test

* fix integration test
matt-intercom added a commit to intercom/smokescreen that referenced this pull request Jan 4, 2024
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Pull Request Test Coverage Report for Build 5536637412

Warning: This coverage report may be inaccurate.

We've detected an issue with your CI configuration that might affect the accuracy of this pull request's coverage report.
To ensure accuracy in future PRs, please see these guidelines.
A quick fix for this PR: rebase it; your next report should be accurate.

  • 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
  • No unchanged relevant lines lost coverage.
  • Overall coverage increased (+0.1%) to 62.584%

Totals Coverage Status
Change from base Build 5358361284: 0.1%
Covered Lines: 1298
Relevant Lines: 2074

💛 - Coveralls

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3 participants