🛡️ Sentinel: [HIGH] Fix IPv6 scope_id injection vulnerability

[ManupaKDU]

🚨 Severity: HIGH
💡 Vulnerability: The Python ipaddress module loosely parses the scope_id of IPv6 addresses, potentially allowing arbitrary characters (such as newlines, spaces, or shell metacharacters) to be present in the ip_obj.scope_id attribute. When str(ip_obj) is executed, these arbitrary characters are included in the string output. In this codebase, the parsed IP string is passed directly into subprocess.call arguments. If an attacker provides a crafted IPv6 address like fe80::1%eth0;rm -rf / or fe80::1%eth0\nls, it could theoretically lead to argument or log injection, exploiting the underlying shell execution.
🎯 Impact: Potential argument and log injection. If an attacker could feed malformed IP configurations into the is_reachable routine, they could disrupt logs or manipulate subprocess arguments.
🔧 Fix: Implemented a regex fullmatch check (r'[\w\-]+') to strictly validate the scope_id of the ipaddress.IPv6Address object. If the scope_id is invalid, the function securely logs an error (using repr() to prevent log injection) and returns False. Added explicit testing in test_testping1.py.
✅ Verification: Ran python3 -m unittest test_testping1.py. The added tests simulating a malicious scope_id now pass successfully. No regressions were introduced.

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PR created automatically by Jules for task 12418624759798404454 started by @ManupaKDU

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