libassh reference manual

Table of contents Headers list All declarations

libassh reference manual » Design and architecture » Software interfaces » Error handling

1 What is libassh ?
- 1.1 Event based ssh
- 1.2 Modular ssh
- 1.3 Clean design
- 1.4 Portable ssh
- 1.5 Security
- 1.6 Performances
- 1.7 Testing
2 Quickstart
3 Design and architecture
- 3.1 Protocol architecture
  - 3.1.1 Transport layer and packets
  - 3.1.2 Key-exchange process and methods
  - 3.1.3 SSH services
  - 3.1.4 The connection protocol
  - 3.1.5 Mapping to libassh components
- 3.2 Software interfaces
  - 3.2.1 Core and modules
  - 3.2.2 Event based API
  - 3.2.3 Helper functions
  - 3.2.4 Channels and requests
  - 3.2.5 Timeout management
  - 3.2.6 Error handling
- 3.3 State machines
  - 3.3.1 Transport layer FSMs
  - 3.3.2 User auth FSMs
  - 3.3.3 Connection layer FSMs
  - 3.3.4 Key exchange FSMs
- 3.4 Source tree
- 3.5 Build configuration
4 Algorithms and methods
- 4.1 Algorithms registration
- 4.2 Key-exchange algorithms
- 4.3 Authentication algorithms
- 4.4 Cipher algorithms
- 4.5 Message authentication algorithms
- 4.6 Compression algorithms
- 4.7 User authentication methods
- 4.8 Key types and formats
5 Example applications
- 5.1 Remote command execution
- 5.2 Simple loopback server
- 5.3 Command line client
- 5.4 Forwarded command execution
- 5.5 POSIX server
- 5.6 SSH key management tool
6 Test programs
7 API documentation
- 7.1 Headers list
- 7.2 All declarations
8 SSH Lexicon
9 Copyright and license
- 9.1 Software License
- 9.2 Copyright owner
- 9.3 Derivative work
- 9.4 Copying this document
10 Bibliography
11 Appendix
12 GNU Free Documentation License

3.2.6 Error handling

Most functions of the library that may fail have assh_status_t as return type. The function return value is used exclusively for error reporting. Any other value that need to be returned is passed using pointer parameters.

When a function call is successful, it returns the ASSH_OK value which is defined as 0. Additionally the ASSH_NO_DATA and ASSH_NOT_FOUND values can be reported by some specific functions of the API and are not considered as errors.

Any other non zero status indicates an error. This can be tested using the ASSH_SUCCESS macro. In case of error, the returned status is composed of two parts: the error code and the error severity that can be extracted by using the ASSH_STATUS and ASSH_SEVERITY macros respectively.

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