[mendsec]

💡 What: Replaced strings.Split and strings.Join with zero-allocation string slicing inside VendorFromMAC.
🎯 Why: strings.Split dynamically allocates slices and new strings. In tight iteration loops (e.g., extracting vendors during large network scans), this adds unnecessary GC pressure and heap allocations.
📊 Impact: Expected to cut execution time by roughly 50% for this particular extraction, eliminating at least two heap allocations per function call.
🔬 Measurement: Verified with a Go benchmark test that demonstrated an improvement from ~588ns/op to ~302ns/op locally.

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PR created automatically by Jules for task 12809800747877946798 started by @mendsec

[google-labs-jules]

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[gemini-code-assist]

Code Review

This pull request optimizes the VendorFromMAC function in pkg/fingerprint/oui.go by replacing strings.Split and strings.Join with zero-allocation string slicing to prevent GC bottlenecks, and documents this optimization in .jules/bolt.md. Feedback on the changes points out a functional discrepancy where malformed MAC addresses (e.g., with a third octet longer than two characters) could result in false-positive OUI matches. A code suggestion is provided to ensure that if the MAC address is longer than 8 characters, the character at index 8 is verified to be a separator.

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[gemini-code-assist]

The current zero-allocation optimization has a functional discrepancy compared to the original strings.Split implementation when handling malformed MAC addresses.

Specifically, if a MAC address has a third octet longer than 2 characters (e.g., B8:27:EB123), the original code would split it into ["B8", "27", "EB123"] and join the first 3 parts to get "B8:27:EB123" (which does not match any OUI). However, the new implementation only checks mac[2] == ':' && mac[5] == ':' and then slices mac[:8], which yields "B8:27:EB" and incorrectly matches the OUI.

To prevent false positives on malformed MAC addresses, we should ensure that if the MAC address is longer than 8 characters, the character at index 8 is a separator (:).

Suggested change

	if len(mac) >= 8 && mac[2] == ':' && mac[5] == ':' {
	prefix := mac[:8]
	if len(mac) >= 8 && mac[2] == ':' && mac[5] == ':' && (len(mac) == 8 || mac[8] == ':') {
	prefix := mac[:8]

[mendsec]

Closing as superseded by #50, which is the chosen OUI optimization line.

[google-labs-jules]

Closing as superseded by #50, which is the chosen OUI optimization line.

Understood. Acknowledging that this work is now obsolete and stopping work on this task.