[PROTON-2622] TLS OpenSSL library: ensure capacity values match given capacity

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: proton-c-0.38.0
• Fix Version/s: proton-c-0.38.0
• Component/s: proton-c
• Assignee: Clifford Jansen
• Reporter: Ken Giusti
• Created: 11/Oct/22 19:29
• Updated: 11/Nov/22 14:37
• Resolved: 31/Oct/22 20:15

Description

 pn_tls_get_encrypt/decrypt_input_buffer_capacity() unconditionally return the number of empty buffer slots.

However pn_tls_give_encrypt/decrypt_input_buffers() checks the state of the tls session and can take zero buffers even though get capacity returned > 0.

In this case the application will have to "unwind" any buffer allocation/setup work it did expecting there was capacity available.