[bug] proxy: when sequence id is rotated, there may be a wrong ok packet

[volgariver6]

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

issue #16042

What this PR does / why we need it:

when sequence id is rotated, there may be a wrong ok packet.
so do not allow transfer connection when sequence id is rotated.

[matrix-meow]

@volgariver6 Thanks for your contributions!

Pull Request Review:

Problem 1: Lack of Clear Comments

• Description: The code changes lack clear comments explaining the purpose and rationale behind the modifications. Without proper comments, it may be challenging for other developers to understand the intent behind the code changes.
• Suggestion: Add comments to explain the logic behind the changes, especially the new variables like lastSeq, rotated, and the conditions being checked in the kickoff function.

Problem 2: Magic Numbers

• Description: The constants minSequenceID and maxSequenceID are defined as magic numbers (0 and 255 respectively) without clear context or explanation. Magic numbers can make the code harder to understand and maintain.
• Suggestion: Define these constants with meaningful names and add comments to explain their significance in the context of the code.

Problem 3: Inconsistent Variable Initialization

• Description: The variable rotated is declared but not initialized, which can lead to unpredictable behavior if its value is not properly managed.
• Suggestion: Initialize the rotated variable when declaring it to ensure predictable behavior and avoid potential bugs.

Problem 4: Potential Logic Issue

• Description: The condition checking for sequence ID rotation may not cover all edge cases. The logic for detecting sequence ID rotation and preventing transfer connection based on this condition could be improved for better accuracy.
• Suggestion: Review the logic for detecting sequence ID rotation thoroughly and consider edge cases where the current implementation may not handle the rotation correctly. Ensure that the condition for rotated is comprehensive and covers all scenarios.

Problem 5: Redundant Code

• Description: The repeated check for len(buf) > 3 could be consolidated to avoid redundancy and improve code readability.
• Suggestion: Consolidate the check for len(buf) > 3 into a single conditional statement to avoid redundancy and improve code maintainability.

Problem 6: Code Optimization

• Description: The prepareNextMessage function could be optimized for better readability and maintainability by breaking down the logic into smaller, more focused functions.
• Suggestion: Consider refactoring the prepareNextMessage function into smaller, more modular functions that handle specific tasks, making the code easier to understand and maintain.

Security Concern:

• Security Issue: The current implementation does not seem to address any security vulnerabilities directly. However, the lack of clear comments and potential logic issues could lead to unintended behavior that might introduce security risks in the future.
• Suggestion: While the current changes do not introduce security vulnerabilities, it is crucial to ensure that the code is well-documented, logically sound, and thoroughly tested to prevent security vulnerabilities from being inadvertently introduced.

By addressing the mentioned problems and suggestions, the pull request can be improved in terms of clarity, maintainability, and potential edge case handling. It is essential to thoroughly review the code changes, add appropriate comments, and ensure the logic for detecting sequence ID rotation is robust and covers all scenarios.