Fix: correct regex for file-preview URL re-signing

[hyongtao-code]

Fixes #25619

The regex patterns for file-preview and image-preview contained an unescaped ?,
which caused incorrect matches such as file-previe or image-previw.
This led to malformed URLs being incorrectly re-signed.

Changes:

• Escape ? in both file-preview and image-preview regex patterns.
• Ensure only valid URLs are re-signed.

Added unit tests to cover:

• Valid file-preview and image-preview URLs (correctly re-signed).
• Misspelled file/image preview URLs (no longer incorrectly matched).

Other:

• Fix a deprecated function datetime.utcnow()

Related with #24180

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Summary

Screenshots

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Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[gemini-code-assist]

Summary of Changes

Hello @hyongtao-code, 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 resolves a bug where unescaped ? characters in URL regex patterns caused incorrect matching and re-signing of malformed file-preview and image-preview URLs. The changes ensure robust URL validation and re-signing, preventing potential issues with file access. Additionally, it updates deprecated datetime function calls to improve code maintainability and consistency.

Highlights

• Regex Correction for URL Re-signing: The regex patterns for file-preview and image-preview URLs have been corrected by escaping the ? character. This prevents incorrect matches and ensures that only valid URLs are considered for re-signing.
• Enhanced URL Validation: The re-signing mechanism now strictly processes only genuinely valid file-preview and image-preview URLs, avoiding malformed URL re-signing that previously occurred due to the unescaped ?.
• New Unit Tests: Comprehensive unit tests have been added to validate the corrected URL re-signing logic. These tests cover scenarios for correctly re-signed valid URLs and confirm that misspelled preview URLs are no longer incorrectly matched.
• Deprecated Function Update: The deprecated datetime.utcnow() function has been replaced with naive_utc_now() across several files, improving code maintainability and addressing best practices for handling timestamps.

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[Copilot]

Pull Request Overview

This PR fixes a regex vulnerability in URL re-signing logic where unescaped ? characters caused incorrect URL pattern matching for file-preview and image-preview endpoints. The fix ensures only valid URLs are re-signed by properly escaping the regex patterns.

Key changes:

• Fixed regex patterns by escaping ? characters in file-preview and image-preview URL matching
• Replaced deprecated datetime.utcnow() calls with naive_utc_now() for future compatibility
• Added comprehensive unit tests to verify correct behavior for valid and misspelled URLs

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
api/models/model.py	Fixed regex patterns by escaping ? in file-preview and image-preview URL matching
api/tests/unit_tests/models/test_model.py	Added unit tests covering valid URL re-signing and protection against misspelled URL matching
api/tests/unit_tests/core/repositories/test_workflow_node_execution_conflict_handling.py	Replaced deprecated datetime.utcnow() with naive_utc_now()
api/tests/test_containers_integration_tests/tasks/test_batch_clean_document_task.py	Replaced deprecated datetime.utcnow() with naive_utc_now()

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[gemini-code-assist]

Code Review

This pull request effectively addresses a bug in the URL re-signing logic by correcting the regular expressions for file-preview and image-preview URLs. The unescaped ? was causing incorrect matches, and this fix resolves that. The inclusion of new unit tests is excellent, as it covers both the valid cases and the previously failing cases with misspelled URLs, ensuring the fix is robust. Additionally, I appreciate the proactive replacement of the deprecated datetime.utcnow() function, which improves the overall health of the codebase. My feedback includes a minor suggestion to enhance the readability of the new regular expressions.

[QuantumGhost]

LGTM