NAME

       nng_ipc - IPC transport

SYNOPSIS

           #include <nng/transport/ipc/ipc.h>

           int nng_ipc_register(void);

DESCRIPTION

       The ipc transport provides communication support between sockets within different processes on the same
       host. For POSIX platforms, this is implemented using UNIX domain sockets. For Windows, this is
       implemented using Windows Named Pipes. Other platforms may have different implementation strategies.

   Registration
       This transport is generally built-in to the core, so no extra steps to use it should be necessary.

   URI Formats
   Traditional Names
       This transport uses URIs using the scheme ipc://, followed by a path name in the file system where the
       socket or named pipe should be created.

           Tip

           On Windows, all names are prefixed by \\.\pipe\ and do not reside in the normal file system. On POSIX
           platforms, the path is taken literally, and is relative to the current directory, unless it begins
           with /, in which case it is relative to the root directory.

           Note

           When using relative paths on POSIX systems, the address used and returned in properties like
           NNG_OPT_LOCADDR and NNG_OPT_URL will also be relative. Consequently, they will only be interpreted
           the same by processes that have the same working directory. To ensure maximum portability and safety,
           absolute paths are recommended whenever possible.

           Note

           If compatibility with legacy nanomsg applications is required, then path names must not be longer
           than 122 bytes, including the final NUL byte. This is because legacy versions of nanomsg cannot
           express URLs longer than 128 bytes, including the ipc:// prefix.

   UNIX Aliases
       The unix:// scheme is an alias for ipc:// and can be used inter-changeably, but only on POSIX systems.

       The purpose of this scheme is to support a future transport making use of AF_UNIX on Windows systems, at
       which time it will be necessary to discriminate between the Named Pipes and the AF_UNIX based transports.

   Abstract Names
       On Linux, this transport also can support abstract sockets. Abstract sockets use a URI-encoded name after
       the scheme, which allows arbitrary values to be conveyed in the path, including embedded NUL bytes. For
       example, the name "a\0b"  would be represented as abstract://a%00b.

           Tip

           An empty name may be used with a listener to request “auto bind” be used to select a name. In this
           case the system will allocate a free name. The name assigned may be retrieved using NNG_OPT_LOCADDR.

           Note

           NNG cannot represent an abstract socket with the empty name.

           Note

           Abstract names do not include the leading NUL byte used in the low-level socket address.

       Abstract sockets do not have any representation in the file system, and are automatically freed by the
       system when no longer in use. Abstract sockets ignore socket permissions, but it is still possible to
       determine the credentials of the peer with NNG_OPT_PEER_UID, etc.

   Socket Address
       When using an nng_sockaddr structure, the actual structure is of type nng_sockaddr_ipc, except for
       abstract sockets, which use nng_sockaddr_abstract.

   Transport Options
       The following transport options are supported by this transport, where supported by the underlying
       platform.

       •   NNG_OPT_IPC_PERMISSIONS

       •   NNG_OPT_IPC_SECURITY_DESCRIPTOR

       •   NNG_OPT_LOCADDR

       •   NNG_OPT_REMADDR

       •   NNG_OPT_PEER_GID

       •   NNG_OPT_PEER_PID

       •   NNG_OPT_PEER_UID

       •   NNG_OPT_PEER_ZONEID

       •   NNG_OPT_URL

SEE ALSO

       nng_sockaddr(5), nng_ipc_options(5), nng_options(5), nng(7)

                                                   2025-02-02                                         NNG_IPC(7)