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cloudflare / speedtest

Component to perform network speed tests against Cloudflare's edge network
https://speed.cloudflare.com
MIT License
459 stars 34 forks source link

Fix #15 - Transfer size 0 in Safari #18

Closed vasturiano closed 1 year ago

vasturiano commented 1 year ago

When doing cross-origin requests in Safari, the ResourceTiming transferSize field is force set to 0. There is more background into this behaviour in this issue: https://github.com/w3c/resource-timing/issues/222

The consequence is that download bandwidth calculations were using the value of this field as the numerator of the size/time equation, if it was present, leading to a miscalculation of 0 bps in these circumstances. This PR fixes that by interpreting a transfer size of 0 as a missing field, and falling back to an estimation of the transfer size based on the bytes that were requested. This addresses https://github.com/cloudflare/speedtest/issues/15.

To note that this security behaviour only happens if the request is cross-origin, which explains why the issue isn't visible on the site https://speed.cloudflare.com since both the client and the server are on the same domain.

It also only affects Safari based browsers.

In addition, dev dependencies are bumped in this PR.

github-actions[bot] commented 1 year ago

Please set a semver versioning label of either major, minor, or patch on this pull request.