tls13: reject zero length session ticket, and add test.

[philljj]

Description

• tls13.c, DoTls13NewSessionTicket: reject a zero-length session ticket.

Testing

Added unit test:

• test_tls13_zero_length_session_ticket

./configure --enable-tls13 --enable-session-ticket --enable-debug && make
./tests/unit.test -test_tls13_zero_length_session_ticket

[Copilot]

Pull request overview

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Rejects malformed TLS 1.3 NewSessionTicket messages with a zero-length ticket and adds coverage to ensure the client rejects this case.

Changes:

• Add a TLS 1.3 unit test that injects a NewSessionTicket with ticket_length=0 and asserts the client returns BUFFER_ERROR.
• Update TLS 1.3 ticket parsing to explicitly reject zero-length session tickets before calling SetTicket.
• Register the new unit test in the TLS 1.3 test header/group list.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
tests/api/test_tls13.h	Declares and registers test_tls13_zero_length_session_ticket.
tests/api/test_tls13.c	Adds a memio-based test that injects a zero-length ticket NewSessionTicket.
src/tls13.c	Adds an explicit length == 0 rejection in DoTls13NewSessionTicket.

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[github-actions]

MemBrowse Memory Report

gcc-arm-cortex-m0plus

• FLASH: .text +12 B (+0.0%, 64,363 B / 262,144 B, total: 25% used)

gcc-arm-cortex-m3

• FLASH: .text +8 B (+0.0%, 123,091 B / 262,144 B, total: 47% used)

gcc-arm-cortex-m4-openssl-compat

• FLASH: .text +256 B (+0.0%, 775,100 B / 1,048,576 B, total: 74% used)
• RAM: .data +8 B (+0.0%, 136,944 B / 262,144 B, total: 52% used)

gcc-arm-cortex-m4-tls12

• FLASH: .text +64 B (+0.1%, 123,891 B / 262,144 B, total: 47% used)

linuxkm-standard

• Data: __patchable_function_entries +72 B (+0.1%, 49,280 B)
  No memory changes detected for:
• gcc-arm-cortex-m4
• gcc-arm-cortex-m4-baremetal
• gcc-arm-cortex-m4-crypto-only
• gcc-arm-cortex-m4-dtls13
• gcc-arm-cortex-m4-min-ecc
• gcc-arm-cortex-m4-pkcs7
• gcc-arm-cortex-m4-pq
• gcc-arm-cortex-m4-rsa-only
• gcc-arm-cortex-m4-sp-math
• gcc-arm-cortex-m4-tls13
• gcc-arm-cortex-m7
• gcc-arm-cortex-m7-pq
• gcc-arm-cortex-m7-tls13
• linuxkm-pie
• stm32-sim-stm32h753