fix: Refactor isURL() to use Built-in URL Constructor

[lahirumaramba]

Replace the RegEx-based validation in isURL() (which was prone to ReDoS) with the standard built-in URL constructor. This improves security, code simplicity, and correctness by leveraging the platform's native URL parsing.

[gemini-code-assist]

Summary of Changes

Hello @lahirumaramba, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request implements a crucial security enhancement by addressing a potential ReDoS vulnerability in the isURL validator. The core change involves refining the regular expression responsible for hostname validation, making it more resilient against malicious inputs that could lead to excessive processing time. Complementary to this fix, a comprehensive suite of new tests has been introduced to rigorously verify the updated validator's behavior under various conditions, including long and complex URLs, ensuring both security and performance.

Highlights

• ReDoS Vulnerability Fix: The regular expression used for hostname validation within the isURL utility function has been updated to prevent a potential Regular Expression Denial of Service (ReDoS) vulnerability. The change removes an optional group that could lead to excessive backtracking.
• Enhanced URL Validation Tests: New test cases have been added to the isURL function's test suite. These tests specifically target ReDoS scenarios, ensuring the validator handles long valid and invalid URLs efficiently, and verifies the strict validation of dot usage in hostnames.

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Changelog

• src/utils/validator.ts
  • Updated the hostname validation regular expression within the isURL function to prevent a potential ReDoS vulnerability by modifying the ([.]?[a-zA-Z0-9]+[\w-]*)*$ part to (\.[a-zA-Z0-9]+[\w-]*)*$.
• test/unit/utils/validator.spec.ts
  • Added a new test suite for isURL focusing on ReDoS and long input scenarios.
  • Introduced tests to ensure quick handling of long valid URLs and long invalid URLs (ReDoS check) within a specified timeout.
  • Included a test to verify the correct rejection of invalid dot patterns in hostnames, such as 'a..b'.

Activity

• The pull request was created by lahirumaramba.
• No human activity (comments, reviews, approvals) has been recorded yet.

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[gemini-code-assist]

Code Review

This pull request correctly addresses a potential Regular Expression Denial of Service (ReDoS) vulnerability in the URL validator. The fix involves making the hostname validation regex stricter by removing an optional character within a repeated group, which prevents catastrophic backtracking. The accompanying tests are well-designed, verifying the fix and ensuring there are no performance regressions with long or invalid URLs. I have one suggestion to further simplify the regex for improved readability and performance.

[lahirumaramba]

/gemini review

[gemini-code-assist]

Code Review

This pull request successfully refactors the isURL() function to utilize the built-in URL constructor, which is a significant improvement for security by mitigating ReDoS vulnerabilities and enhancing code simplicity. The addition of new tests for long URLs and ReDoS checks is also highly commendable. However, there are a couple of points regarding validation behavior that need clarification or adjustment to ensure consistency and maintain the desired level of strictness.

[gemini-code-assist]

The original isURL function included a specific regex (pathnameRe) to validate the pathname component, ensuring it only contained a defined set of safe characters. This new implementation removes that validation, relying solely on the URL constructor. The URL constructor is very permissive with pathnames (e.g., it will encode spaces), which might allow URLs that were previously considered invalid by this utility. This is a significant change in validation behavior and could potentially lead to unexpected behavior or security vulnerabilities if the stricter pathname validation was a requirement. Please consider re-introducing a similar level of pathname validation if the original strictness is still desired.

[gemini-code-assist]

The new hostname regex ^[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?)*$ explicitly disallows underscores (_) in hostnames. While this aligns better with RFC standards for hostnames and makes an existing test pass, the PR description states the goal is to "match previous behavior". The old regex technically allowed _ via \w. It would be clearer to acknowledge this as an intentional improvement for RFC compliance rather than matching previous behavior, or to clarify if the previous url.parse implicitly rejected underscores despite the regex.