Miscellaneous

This chapter discusses some interfaces that don’t really fit anywhere else.

Get Random Number

uint32_t nng_random(void);

The nng_random returns a random number. The value returned is suitable for use with cryptographic functions such as key generation, and is obtained using platform-specific cryptographically strong random number facilities when available.

Create Socket Pair

int nng_socket_pair(int fds[2]);

The nng_socket_pair function creates a pair of connected file descriptors. These file descriptors, which are returned in the fds array, are suitable for use with the Socket transport.

On POSIX platforms, this is a thin wrapper around the standard socketpair function, using the AF_UNIX family and the SOCK_STREAM socket type. 1

This will return zero on success, or an error number. On platforms that lack this capability, such as Windows, it will return NNG_ENOTSUP.

tip

This function may be useful for creating a shared connection between a parent process and a child process on UNIX platforms, without requiring the processes use a shared filesystem or TCP connection.

Report Library Version

const char * nng_version(void);

The nng_version function returns a human readable version number for NNG, formatted as a NUL-terminated string.

Additionally, compile time version information is available via some predefined macros:

  • NNG_MAJOR_VERSION: Major version number.
  • NNG_MINOR_VERSION: Minor version number.
  • NNG_PATCH_VERSION: Patch version number.

NNG is developed and released using Semantic Versioning 2.0, and the version numbers reported refer to both the API and the library itself. (The ABI – application binary interface – between the library and the application is controlled in a similar, but different manner depending upon the link options and how the library is built.)

1: At present only POSIX platforms implementing socketpair support this function.