PosixSocket

This npm module makes the POSIX Socket API available to node with minimal changes.

* sockfd = socket(domain, type, protocol)
* bind(sockfd, addr)
* accept(sockfd, addr)
* connect(sockfd, addr)
* send(sockfd, buf, len, flags)
* sendto(sockfd, buf, len, flags, dest_addr)
* recv(sockfd, buf, len, flags)
* recvfrom(sockfd, buf, len, flags, src_addr)
* close(fd)
* shutdown(sockfd, how)
* getsockopt(sockfd, level, optname)
* setsockopt(sockfd, level, optname, optval)

Differences with the POSIX Socket API:

1. Socket addresses are specified as JavaScript objects.
Currently, only three address families are supported:
* Local/Unix (sockaddr_un): {sun_family:1, sun_path:"path/to/unix-sock.sock"}.
* Inet (sockaddr_in): {sin_family:2, sin_port:8080, sin_addr:"127.0.0.1"}.
* Inet6 (sockaddr_in6): {sin6_family:24, sin6_port:8080, sin6_flowinfo:0, sin6_addr:"::1", sin6_scope_id:0}.
2. The length of socket addresses is computed by the module.
3. In getsockopt and setsockopt: optval can only be a number.

I made this module to perform fast synchronous communication between node processes.
Please, don't ask me why I needed the perform synchronous communication.
Without C++ addon, this can only be achieved with the synchronous API of fs / child_process.
Both these solutions are incredibly inefficient.

Example

Server

``js
const PosixSocket = require("posix-socket");
const sockfd = PosixSocket.socket(PosixSocket.AF_UNIX, PosixSocket.SOCK_STREAM, 0);
PosixSocket.bind(sockfd, {
sun_family: PosixSocket.AF_UNIX,
sun_path: "/tmp/yo.sock"
});
PosixSocket.listen(sockfd, 1);
const address = {};
const sockfd1 = PosixSocket.accept(sockfd, address);
console.log("connection accepted from", address);
const buffer = new ArrayBuffer(100);
const size = PosixSocket.recv(sockfd1, buffer, buffer.byteLength, 0);
console.log("got: <"+String.fromCharCode.apply(null, new Uint16Array(buffer, 0, size))+">");
PosixSocket.close(sockfd);
require("fs").unlinkSync("/tmp/yo.sock");
`

Client

`js
const PosixSocket = require("posix-socket");
const sockfd = PosixSocket.socket(PosixSocket.AF_UNIX, PosixSocket.SOCK_STREAM, 0);
PosixSocket.connect(sockfd, {
sun_family: PosixSocket.AF_UNIX,
sun_path: "/tmp/yo.sock"
});
const buffer = new ArrayBuffer(100);
const view = new Uint16Array(buffer, 0, buffer.length);
const string = "HelloWorld!";
for (let i = 0; i view[i] = string.charCodeAt(i);
PosixSocket.send(sockfd, buffer, string.length*view.BYTES_PER_ELEMENT, 0);
PosixSocket.close(sockfd);
``

Troubleshooting

https://github.com/nodejs/node-gyp/blob/master/macOS_Catalina.md