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| -rw-r--r-- | docs/ref/SUMMARY.md | 5 | ||||
| -rw-r--r-- | docs/ref/tran/ipc.md | 100 |
2 files changed, 103 insertions, 2 deletions
diff --git a/docs/ref/SUMMARY.md b/docs/ref/SUMMARY.md index b0dd9f51..5813961d 100644 --- a/docs/ref/SUMMARY.md +++ b/docs/ref/SUMMARY.md @@ -61,8 +61,9 @@ - [Transports](./tran/index.md) - - [BSD Socket](./tran/socket.md) - [Intra-Process Transport](./tran/inproc.md) - - [UDP](./tran/udp.md) + - [Inter-Process Transport](./tran/ipc.md) + - [BSD Socket (Experimental)](./tran/socket.md) + - [UDP Transport (Experimental)](./tran/udp.md) [Index](./indexing.md) diff --git a/docs/ref/tran/ipc.md b/docs/ref/tran/ipc.md new file mode 100644 index 00000000..ebf2fe89 --- /dev/null +++ b/docs/ref/tran/ipc.md @@ -0,0 +1,100 @@ +# IPC Transport + +## DESCRIPTION + +The {{i:*ipc* transport}}{{hi:*ipc*}} provides communication support between +sockets within different processes on the same host. +For POSIX platforms, this is implemented using {{i:UNIX domain sockets}}. +For Windows, this is implemented using Windows {{i:named pipes}}. +Other platforms may have different implementation strategies. + +### URI Formats + +#### Traditional Names + +This transport uses URIs using the scheme {{i:`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 {{i:`unix://`}} scheme is an alias for `ipc://` and can be used inter-changeably, but only on POSIX systems. +{{footnote: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 {{i:abstract sockets}}. +Abstract sockets use a URI-encoded name after the {{i:`abstract://`}} 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 [{{i:`NNG_OPT_LOCADDR`}}][NNG_OPT_LOCADDR]. + +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 [{{i:`NNG_OPT_PEER_UID`}}][NNG_OPT_PEER_UID], and similar options. +{{footnote: This property makes it important that names be chosen randomly to +prevent unauthorized access, or that checks against the peer credentials are made, or ideally, both.}} + +### Socket Address + +When using an [`nng_sockaddr`][sockaddr] structure, +the actual structure is of type [`nng_sockaddr_ipc`][sockaddr_ipc], +except for abstract sockets, which use [`nng_sockaddr_abstract`][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_PERMISSIONS] +- [`NNG_OPT_IPC_SECURITY_DESCRIPTOR`][NNG_OPT_IPC_SECURITY_DESCRIPTOR] +- [`NNG_OPT_LOCADDR`][NNG_OPT_LOCADDR] +- [`NNG_OPT_REMADDR`][NNG_OPT_REMADDR] +- [`NNG_OPT_PEER_GID`][NNG_OPT_PEER_GID] +- [`NNG_OPT_PEER_PID`][NNG_OPT_PEER_PID] +- [`NNG_OPT_PEER_UID`][NNG_OPT_PEER_UID] +- [`NNG_OPT_PEER_ZONEID`][NNG_OPT_PEER_ZONEID] +- [`NNG_OPT_URL`][NNG_OPT_URL] + +[NNG_OPT_IPC_PERMISSIONS]: TODO.md +[NNG_OPT_IPC_SECURITY_DESCRIPTOR]: TODO.md +[NNG_OPT_LOCADDR]: TODO.md +[NNG_OPT_REMADDR]: TODO.md +[NNG_OPT_PEER_GID]: TODO.md +[NNG_OPT_PEER_PID]: TODO.md +[NNG_OPT_PEER_UID]: TODO.md +[NNG_OPT_PEER_ZONEID]: TODO.md +[NNG_OPT_URL]: TODO.md +[sockaddr]: TODO.md +[sockaddr_ipc]: TODO.md +[sockaddr_abstract]: TODO.md |
