THRIFT-6142: Enforce Ruby unframed HeaderTransport limits

[kpumuk]

Ruby HeaderTransport enforced max_frame_size for Header and framed clients but passed unframed Binary and Compact reads directly to the underlying transport without applying the configured limit.

This change counts bytes consumed by each unframed protocol message, including the initial protocol signature, and raises TransportException::SIZE_LIMIT before a read would exceed the configured maximum. Pure-Ruby and native protocol readers notify compatible transports at message boundaries so sequential messages receive independent budgets. Exact-limit messages and partial underlying reads remain supported.

Benchmarks

Ruby 4.0.6 on aarch64 Linux, seven warmed trials per revision.

The repository protocol benchmark was run with and without the native extension:

ruby test/rb/benchmarks/protocol_benchmark.rb \
  --small-runs 10000 \
  --scenarios hdr-bin-read-small,hdr-cmp-read-small \
  --json

THRIFT_BENCHMARK_SKIP_NATIVE=1 ruby \
  test/rb/benchmarks/protocol_benchmark.rb \
  --small-runs 10000 \
  --scenarios hdr-bin-read-small,hdr-cmp-read-small \
  --json

Scenario	master median (range)	this change median (range)	Delta
Pure Header Binary	0.292063 s (0.289148–0.294775)	0.293295 s (0.287210–0.299563)	+0.42%
Pure Header Compact	0.283662 s (0.279885–0.296288)	0.282497 s (0.277990–0.292476)	-0.41%
Native-loaded Header Binary	0.241813 s (0.238484–0.245131)	0.242277 s (0.238585–0.254646)	+0.19%
Native-loaded Header Compact	0.185282 s (0.184773–0.189132)	0.183141 s (0.182184–0.193690)	-1.16%

A focused worst-case control decoded 100,000 sequential minimal unframed messages per trial through HeaderTransport, using 19-byte Binary and 11-byte Compact messages. Pure mode used ruby -Ilib -rthrift; native mode added -Iext and used BinaryProtocolAccelerated for the Binary reader.

Scenario	master median (range)	this change median (range)	Delta
Pure unframed Binary	0.517964 s (0.510047–0.532928)	0.544925 s (0.535836–0.550106)	+5.21%
Pure unframed Compact	0.482962 s (0.481741–0.491921)	0.522609 s (0.517260–0.526999)	+8.21%
Native accelerated unframed Binary	0.462682 s (0.459623–0.478828)	0.488974 s (0.486336–0.506783)	+5.68%
Native unframed Compact	0.413511 s (0.408578–0.423356)	0.452232 s (0.447174–0.465880)	+9.36%

The focused control intentionally maximizes fixed per-message accounting overhead and uses an in-memory transport, so it does not include network or application work. The repository Header scenarios remain within trial noise.

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[Copilot]

Pull request overview

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This PR fixes a gap in Ruby HeaderTransport where unframed Binary/Compact reads bypassed max_frame_size, adding byte accounting and size-limit enforcement for unframed messages (including protocol signatures) and resetting budgets at message boundaries.

Changes:

• Track and enforce unframed message byte budgets in HeaderTransport, raising TransportException::SIZE_LIMIT before exceeding max_frame_size.
• Reset unframed size budgets at message boundaries by notifying transports from pure-Ruby and native protocol read_message_begin.
• Add specs covering exact-limit acceptance, over-limit rejection, signature handling, partial reads, and sequential message budgeting (incl. accelerated binary).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/rb/spec/header_transport_spec.rb	Adds tests validating unframed size-limit enforcement and per-message budgeting.
lib/rb/lib/thrift/transport/header_transport.rb	Implements unframed byte accounting, limit checks, and message-boundary resets.
lib/rb/lib/thrift/protocol/compact_protocol.rb	Notifies transports of new-message boundaries to reset unframed budgets.
lib/rb/lib/thrift/protocol/binary_protocol.rb	Notifies transports of new-message boundaries to reset unframed budgets.
lib/rb/ext/thrift_native.c	Interns reset_message_size method ID for native protocol boundary notifications.
lib/rb/ext/constants.h	Exposes reset_message_size method ID for native extension usage.
lib/rb/ext/compact_protocol.c	Calls reset_message_size at message start in native compact reader.
lib/rb/ext/binary_protocol_accelerated.c	Calls reset_message_size at message start in accelerated binary reader.

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