dhcpcd: size the escaped-SSID buffers for the worst case

[akiernan]

print_string() renders each non-printable byte as \NNN - four characters plus terminating NUL, failing with ENOBUFS if there is no room for it. An SSID is up to IF_SSIDLEN (32) bytes, so an escaped SSID needs up to (IF_SSIDLEN * 4) + 1 = 129 bytes.

dhcpcd_selectprofile() uses PROFILE_LEN, which is 64 causing:

dhcpcd_selectprofile: No buffer space available

in the log, the resulting call to read_config() then gets an an empty SSID, so no profile ssid ... block matches.

dhcpcd_reportssid() uses IF_SSIDLEN * 4, which is 128 and correct except for the NUL, so it fails only on a 32-byte SSID whose every byte escapes. It then logs an error instead of the "connected to Access Point" line.

Closes #726

[coderabbitai]

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• src/dhcpcd.c

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Walkthrough

The change increases both escaped SSID buffers by one byte. This provides space for the terminating NUL byte in dhcpcd_selectprofile and dhcpcd_reportssid.

Changes

SSID buffer sizing

Layer / File(s)	Summary
Expand SSID formatting buffers src/dhcpcd.c	Both SSID formatting buffers now use (IF_SSIDLEN * 4) + 1 bytes.

Priority: ➖ Normal — Impact reflects medium issue severity.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 9ae8b

Escaped maximum-length SSIDs can now be matched and reported without running out of buffer space. The targeted sizing correction is ready to merge.

Suggested reviewers: rsmarples

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: sizing escaped-SSID buffers for the worst case.
Description check	✅ Passed	The description directly explains the buffer-sizing defect, its impact, and the fix for both affected functions.
Linked Issues check	✅ Passed	The changes satisfy issue #726 by allocating (IF_SSIDLEN * 4) + 1 bytes in both escaped-SSID buffers, preserving NUL termination and addressing profile matching and reporting failures.
Out of Scope Changes check	✅ Passed	The two buffer-size changes are directly related to issue #726 and the stated objectives. No unrelated changes are present.

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[ColinMcInnes]

I agree, no security hole here, just a truncated log, and this should resolve that.