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Fix test_strip_headers_on_redirect's URL-embedded-credentials cases#3678

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bdarnell merged 1 commit into
tornadoweb:masterfrom
bdarnell:claude/tornado-issue-3674-mnyaxn
Jul 4, 2026
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Fix test_strip_headers_on_redirect's URL-embedded-credentials cases#3678
bdarnell merged 1 commit into
tornadoweb:masterfrom
bdarnell:claude/tornado-issue-3674-mnyaxn

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@bdarnell bdarnell commented Jul 4, 2026

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Summary

Updated the test_strip_headers_on_redirect test to correctly handle credential injection in redirect URLs and account for a known libcurl regression with same-origin redirects.

Key Changes

  • Modified credential injection in redirect URLs to only replace the first occurrence of "http://" instead of all occurrences. This prevents credentials from being added to both the outer URL being fetched and the redirect target URL in the query parameter, which would cause libcurl to honor the redirect's explicit credentials instead of stripping them.
  • Added conditional assertion logic for the "credentials in URL" test case to account for a known libcurl regression (versions 8.20/8.21 and later) where credentials embedded in URLs are incorrectly dropped across same-origin redirects with absolute Location headers.
  • Added detailed comments explaining the credential handling behavior and the libcurl regression.

Implementation Details

  • The fix uses the third parameter of str.replace() to limit replacements to the first occurrence only
  • The conditional check specifically exempts the "credentials in URL" test case from asserting that auth headers are preserved on same-origin redirects, while other test cases (using Authorization headers or Cookies) continue to verify preservation
  • The change is non-breaking and only affects test assertions, not the actual HTTP client implementation

https://claude.ai/code/session_01TJzTuZ43muUDrzWjew2D3u

Fixes #3674

url.replace("http://", ...) replaced every occurrence of "http://" in
the fetched URL, including the one inside the "url" query parameter
that RedirectHandler uses as the redirect target. That accidentally
embedded the test credentials in the Location header's URL too, so
the "different origin" subtest was actually exercising "does libcurl
honor credentials the server explicitly put in the redirect target"
rather than "does libcurl strip credentials carried over from the
original request" - libcurl correctly does the former, which is not
a credential leak.

Limit the replacement to the first occurrence so only the outer,
fetched URL carries the test credentials.

Separately, the "same origin" subtest for this case now surfaces an
actual libcurl regression (still present in curl's git master as of
this writing): credentials embedded in the URL are dropped across a
same-origin redirect when the Location header is an absolute URL
(a relative Location correctly preserves them). This isn't a security
issue since nothing leaks to another origin, so that specific
assertion is skipped rather than asserted either way.
@bdarnell bdarnell merged commit b689e0e into tornadoweb:master Jul 4, 2026
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Test regression with pycurl 7.47.0: test_strip_headers_on_redirect; Authorization header is not stripped

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