Modbus/TCP Security

[kevinherron]

Adds support for Modbus/TCP Security (Modbus over TLS).

See https://modbus.org/docs/MB-TCP-Security-v21_2018-07-24.pdf

[Copilot]

Copilot reviewed 11 out of 26 changed files in this pull request and generated 4 comments.

Files not reviewed (15)

• modbus-tests/pom.xml: Language not supported
• modbus-serial/src/main/java/com/digitalpetri/modbus/serial/server/SerialPortServerTransport.java: Evaluated as low risk
• modbus/src/main/java/com/digitalpetri/modbus/server/ModbusRtuServer.java: Evaluated as low risk
• modbus/src/main/java/com/digitalpetri/modbus/server/ModbusTcpServer.java: Evaluated as low risk
• modbus/src/main/java/com/digitalpetri/modbus/server/ModbusTcpServerTransport.java: Evaluated as low risk
• modbus/src/main/java/com/digitalpetri/modbus/server/ModbusRtuServerTransport.java: Evaluated as low risk
• modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/server/NettyServerTransportConfig.java: Evaluated as low risk
• modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/client/NettyClientTransportConfig.java: Evaluated as low risk
• modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/server/NettyTcpServerTransport.java: Evaluated as low risk
• modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/client/NettyTcpClientTransport.java: Evaluated as low risk
• modbus-tests/src/test/java/com/digitalpetri/modbus/test/CertificateUtil.java: Evaluated as low risk
• modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/server/NettyRtuServerTransport.java: Evaluated as low risk
• modbus/src/main/java/com/digitalpetri/modbus/server/authz/AuthzHandler.java: Evaluated as low risk
• modbus/src/main/java/com/digitalpetri/modbus/server/ModbusRequestContext.java: Evaluated as low risk
• modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/client/NettyRtuClientTransport.java: Evaluated as low risk

Comments suppressed due to low confidence (2)

modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/server/NettyRequestContext.java:58

• [nitpick] The magic number 4 used for stripping the leading tag and length bytes should be defined as a constant for better readability.

clientRole = new String(bs, 4, bs.length - 4);

modbus-tcp/src/main/java/com/digitalpetri/modbus/tcp/server/NettyRequestContext.java:46

• Ensure that the clientRole extraction logic is covered by tests.

public Optional<String> clientRole() {