v0.4.0

Added

• TcpTransportBuilder with configurable allocation limit for DoS protection
• Automatic key extension for AES-192/256 and 3DES privacy protocols

Changed

• Breaking: Redesigned error types around caller actions and boxed Error for smaller Results
• Breaking: TrapV1Pdu::v2_trap_oid() now returns Result to handle invalid trap values
• Use explicit tracing targets with brace syntax for stable log filtering
• Reduced BER MAX_LENGTH from 16MB to 2MB
• Use getrandom for salt initialization and skip zero on wraparound
• Compute VarBind::encoded_size() arithmetically instead of allocating

Fixed

• Pdu::decode rejecting valid GETBULK requests
• OID first subidentifier overflow during BER encoding
• Enforce MAX_OID_LEN during BER decode per RFC 2578 Section 3.5
• PDU error_index and GETBULK parameter validation during decode
• Integer overflow in BER decoder bounds checks
• USM engine_boots/engine_time validation per RFC 3414
• Cap estimated_time() at MAX_ENGINE_TIME per RFC 3414 Section 2.2.1
• Broken doc links