fix: fetch blob with range off-by-one error #4643
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Pull Request Overview
This PR fixes an off-by-one error in the handling of range requests for blob URIs. The rangeEnd parameter in HTTP range requests is inclusive, but the slice operation was not adding 1 as required by the fetch specification, causing the last byte to be omitted.
Key Changes:
- Fixed the blob slice operation to correctly add 1 to
rangeEndto include the final byte - Added a test case to verify that range requests return the correct inclusive byte range
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| lib/web/fetch/index.js | Corrected the blob.slice call to add 1 to rangeEnd, aligning implementation with the fetch specification |
| test/fetch/blob-uri.js | Added test verifying that range requests properly return inclusive byte ranges |
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #4643 +/- ##
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Coverage 92.85% 92.85%
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Files 106 106
Lines 33111 33111
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Hits 30745 30745
Misses 2366 2366 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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severo
approved these changes
Oct 26, 2025
ronag
approved these changes
Oct 26, 2025
tsctx
approved these changes
Oct 26, 2025
KhafraDev
approved these changes
Oct 26, 2025
metcoder95
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Oct 30, 2025
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In a range request, the rangeEnd is meant to be inclusive, but undici has a bug in its handling of range requests on blob uri's that misses the last character.
This relates to...
Fix for nodejs/node#60382
Credit to @severo for discovering this bug.
Rationale
The fetch spec clearly states that:
And funny enough, in the undici code the COMMENT is correct but the code is off by one:
Changes
Fixes the off-by-one error in range requests by adding 1 to the rangeEnd slice.
Includes a test which fails on master but passes with this fix.
Features
n/a
Bug Fixes
Fixes nodejs/node#60382
Breaking Changes and Deprecations
n/a
Status