TNT/docs/CHANGELOG.md

Changelog

2026-05-16 - Internal cleanup

Fixed

• message_load() now holds g_message_file_lock for the duration of the read. Previously :last [N] could race with message_save() and observe a half-written line.
• constant_time_strcmp() accumulates the length difference in size_t instead of unsigned char. The old code lost the length-mismatch signal when the two lengths differed by a multiple of 256.

Changed

• buffer_appendf() and buffer_append_bytes() moved to common.c; the two identical copies in ssh_server.c and tui.c have been removed.
• Removed TODO.md (both items completed) and docs/README.old (superseded by the root README.md).
• Trimmed the auto-generated 2025 entry block from this changelog.

2026-04-23 - Chat UX Commands and MOTD

Added

• :last [N] — show last N messages retrieved directly from the log file (1–50, default 10), bypassing the 100-message in-memory ring buffer limit
• :search <keyword> — case-insensitive full-text search across the entire message history on disk; returns the most recent 15 matches
• :mute-joins — per-client toggle to silence join/leave system notifications; title bar shows [静音] when active
• MOTD support — place motd.txt in the state directory; users see it on connect and press any key to enter chat
• message_search() — new function in message.c / message.h for log file keyword search with rolling result collection
• Updated in-TUI help screens (English and Chinese) with new commands

2026-03-10 - SSH Runtime & Unix Interface Update

Fixed

• moved SSH handshake/auth/channel setup out of the main accept loop
• replaced synchronous room-wide fan-out with room update sequencing and per-client refresh
• switched idle session handling to ssh_channel_poll_timeout() plus blocking reads so quiet sessions are not dropped incorrectly
• made -d/--state-dir create the runtime state directory automatically

Added

• SSH exec commands: help, health, users, stats --json, tail, post
• PTY window-change handling for terminal resize
• TNT_MAX_CONN_RATE_PER_IP for per-IP connection-rate control
• tests/test_exec_mode.sh
• tests/test_connection_limits.sh

Changed

• TNT_MAX_CONN_PER_IP now means concurrent sessions per IP
• stress tests now disable rate-based blocking so they exercise concurrency instead of self-throttling

2026-01-22 - Security Audit Fixes

Comprehensive security hardening addressing 23 identified vulnerabilities across 6 categories.

Critical

• [AUTH] Add optional access token authentication (TNT_ACCESS_TOKEN)
• [AUTH] Implement IP-based rate limiting (10 conn/IP/60s, 5-min block after 5 auth failures)
• [AUTH] Add global connection limits (default: 64, configurable via TNT_MAX_CONNECTIONS)

High Priority

• [BUFFER] Replace all strcpy() with strncpy() (3 locations)
• [BUFFER] Add buffer overflow checking in client_printf()
• [BUFFER] Implement UTF-8 validation to prevent malformed input and overlong encodings
• [SSH] Upgrade RSA key from 2048 to 4096 bits
• [SSH] Fix key file permission race with atomic generation (umask + temp file + rename)
• [SSH] Add configurable bind address (TNT_BIND_ADDR) and log level (TNT_SSH_LOG_LEVEL)
• [CONCURRENCY] Fix room_broadcast() reference counting race
• [CONCURRENCY] Fix tui_render_screen() message array TOCTOU via snapshot approach
• [CONCURRENCY] Fix handle_key() scroll position TOCTOU

Medium Priority

• [INPUT] Add username validation rejecting shell metacharacters and control chars
• [INPUT] Sanitize message content to prevent log injection attacks
• [INPUT] Enhance message_load() with field length and timestamp validation
• [RESOURCE] Convert message position array from fixed 1000 to dynamic allocation
• [RESOURCE] Enhance setup_host_key() validation (size, permissions, auto-regeneration)
• [RESOURCE] Improve thread cleanup with proper pthread_attr and error handling

New Environment Variables

• TNT_ACCESS_TOKEN - Optional password for authentication (backward compatible)
• TNT_BIND_ADDR - Bind address (default: 0.0.0.0)
• TNT_SSH_LOG_LEVEL - SSH logging verbosity 0-4 (default: 1)
• TNT_RATE_LIMIT - Enable/disable rate limiting (default: 1)
• TNT_MAX_CONNECTIONS - Max concurrent connections (default: 64)
• TNT_MAX_CONN_PER_IP - Max connections per IP (default: 5)

Security Summary

Category	Fixes	Impact
Buffer Security	3	Prevents overflows, malformed UTF-8
SSH Hardening	4	Stronger crypto, no races
Input Validation	3	Prevents injection, log poisoning
Resource Management	3	Handles large logs, prevents DoS
Authentication	3	Optional protection, rate limiting
Concurrency Safety	3	Eliminates races, crashes
TOTAL	19	23 vulnerabilities fixed

All changes maintain backward compatibility. Server remains open by default.

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2025-12-02 - Stability & Testing Update

Fixed

• Double colon bug in vim command mode (: key consumed properly)
• strtok data corruption in command output rendering
• Use-after-free race condition (added reference counting)
• SSH read blocking issues (added timeouts)
• PTY request infinite loop
• Message history memory waste (optimized loading)

Added

• Reference counting for thread-safe client cleanup
• SSH read timeout (30s) and error handling
• UTF-8 incomplete sequence detection
• AddressSanitizer build target (make asan)
• Basic functional tests (test_basic.sh)
• Stress testing script (test_stress.sh)
• Static analysis target (make check)
• Developer documentation (HACKING)

Changed

• Improved error handling throughout
• Better memory management in message loading