Fork improvements#2
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July 8, 2026 19:11
Syslog fields are attacker-controlled network input. Values beginning with '=', '+', '-' or '@' are interpreted as formulas by Excel and LibreOffice when the exported CSV is opened, enabling data exfiltration or command execution via DDE on the analyst's workstation. Neutralize hostname, app name, proc id and message fields by prefixing a single quote when they start with a formula trigger character, including triggers smuggled behind leading tab/CR characters. Timestamp, severity/facility labels and protocol are app-generated; source IP comes from the network stack, so these remain untouched.
The previous lexicographic comparison would report "1.10.0" as older than "1.9.0", so the update check would silently stop working once a double-digit version component is released. Compare components as integers, falling back to string comparison only for non-numeric components such as pre-release suffixes.
…ompares DisableEncryption skipped password verification entirely when the in-memory session password was empty — the state after an app restart with a still-locked encrypted database. Any caller could then flip the encryption flag off and desynchronize config state from the encrypted on-disk database. Now, disabling (or changing the password) while encryption is enabled requires a prior successful unlock, and the password checks use crypto/subtle constant-time comparison.
Previously all three listeners (UDP, TCP, TLS) bound unconditionally to all interfaces. On multi-homed hosts — e.g. an engineering laptop attached to both an office network and a control-system network — this exposes the syslog service on networks it was never meant to face. Add an optional BindAddress to ServerConfig, validated as an IP literal, and use net.JoinHostPort so IPv6 addresses work. Empty keeps the previous listen-on-all behavior. Exposed in the server controls UI with translations for all supported locales.
Each accepted connection spawns a handler goroutine with a 64 KiB scan buffer and no upper bound, so a connection-flooding client could bind unbounded memory and goroutines. Introduce a semaphore (512 slots shared by TCP and TLS) acquired non-blockingly on accept; connections beyond the limit are closed immediately and logged. Handlers release into the semaphore instance they were admitted under, so a server restart cannot cause cross-instance releases.
Any host on the local segment could deliver messages, trigger alert rules, and flood the retention window with junk that displaces real events. Add an optional allowlist of IP literals and CIDR ranges, validated in ValidateServerConfig and compiled once at server start. UDP datagrams from non-allowed sources are dropped; TCP/TLS connections are closed on accept before consuming a connection slot. An empty list preserves the previous allow-all behavior. The UI hint documents explicitly that UDP source addresses are spoofable, so the allowlist is network hygiene rather than authentication — mutual TLS remains the mechanism for authenticated senders.
handleTCPConnection blocks in scanner.Scan() with a five-minute read deadline. Cancelling the context does not interrupt an in-progress read, so Stop (which waits on the shared WaitGroup) could block for up to tcpReadTimeout when an idle TCP/TLS connection was open. Track active connections in a map and close them in Stop after the listeners are closed and before waiting on the WaitGroup, unblocking their reads immediately. trackConn returns false once the server is stopping so a connection accepted during shutdown is closed cleanly.
The failed-attempt counter lived only in memory and, on reaching the limit, quit the application. Both are weak: relaunching reset the counter (so the limit was trivially bypassable), and force-quitting is hostile to a legitimate user who simply mistyped. Persist failed attempts and a lockout deadline in the config file. After five consecutive failures an exponential backoff (30s doubling, capped at 15m) is enforced and survives restarts; a successful unlock clears the state. The shift is overflow-guarded so the cap always holds. The unlock screen now reads the authoritative lockout window from the backend and counts it down instead of maintaining its own counter.
A generated CA lived only in memory, so after a restart the CA — and the ability to sign further device certificates against it — was lost. This is impractical for the intended workflow of provisioning multiple devices over time against one trusted root. Persist the CA certificate and key in the config directory. When encryption is enabled the bundle is stored with the same AES-256-GCM/Argon2id scheme as the log database (loaded after unlock); otherwise it is written as plaintext PEM at 0600, and the user is warned that the key rests unencrypted. Enabling/disabling encryption and changing the password re-persist the CA under the new protection. Adds reusable EncryptBytes/DecryptBytes to the storage crypto package (same on-disk format as the file API) to avoid duplicating the crypto.
TCP and TLS messages were split on LF only (RFC 6587 non-transparent framing). RFC 5425 mandates octet counting for syslog over TLS, so many devices send "MSG-LEN SP SYSLOG-MSG" frames that line splitting mangles — and any message legitimately containing a newline was truncated. Add a bufio.SplitFunc that detects octet counting (digit run + space + declared byte length) and otherwise falls back to LF framing, so both wire formats interoperate on the same port. The declared length is bounded by the scan buffer to prevent a hostile MSG-LEN from forcing an unbounded buffer; CR/LF between frames is skipped and trailing CR is stripped from LF-framed messages. The split function is dependency-free and covered by table tests (single/multiple octet frames, embedded newline, LF and CRLF framing, mixed streams, digit-led non-counted messages, incomplete frame at EOF).
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go vet ./...passesgo test -race ./...passessvelte-check --fail-on-warningspasses