Router push to other domain with same prefix

[ReinoutStevens]

Verify canary release

• [X] I verified that the issue exists in the latest Next.js canary release

Provide environment information

/bin/sh: 1: yarn: not found /bin/sh: 1: pnpm: not found

Operating System:
  Platform: linux
  Arch: x64
  Version: #51-Ubuntu SMP Thu Aug 11 07:51:15 UTC 2022
Binaries:
  Node: 16.14.2
  npm: 8.5.0
  Yarn: N/A
  pnpm: N/A
Relevant packages:
  next: 12.1.0
  react: 17.0.2
  react-dom: 17.0.2

warn - Latest canary version not detected, detected: "12.1.0", newest: "12.3.1-canary.3". Please try the latest canary version (npm install next@canary) to confirm the issue still exists before creating a new issue. Read more - https://nextjs.org/docs/messages/opening-an-issue

What browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

Describe the Bug

NextJS router wrongly uses startsWith to see whether a link is running on the same origin or not. This fails when your site is running on example.com, but you push to example.com.br for a Portugese version of your site.

Expected Behavior

Site is running on example.com, example.fr and example.com.br

Example.com calls router.push('https://example.fr'), which works just fine. Example.com calls router.push('https://example.com.br/portugese-page'), which opens example.com/.br/portugese-page instead.

Link to reproduction

https://github.com/ReinoutStevens/nextjs-router

To Reproduce

The minimal example illustrates the problem, but does not reproduce it on localhost as the port number is also taken into account ( and so you cant have localhost:3000 and localhost.com:3000 ).