Windows AF_UNIX UNIX domain socket example

server.c

// Taken from with modifications
// https://devblogs.microsoft.com/commandline/windowswsl-interop-with-af_unix/#windows-server-code

#undef UNICODE

#include <winsock2.h>
#include <windows.h>
#include <ws2tcpip.h>
#include <afunix.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

#define SERVER_SOCKET "server.sock"

int __cdecl main(void)
{
    SOCKET server_socket_fd = INVALID_SOCKET;
    SOCKET client_socket_fd = INVALID_SOCKET;
    int rc = 0;
    char send_buf[] = "AF_UNIX from Windows!";
    SOCKADDR_UN socket_addr = { 0 };
    WSADATA wsa_data = { 0 };

    // Initialize Winsock
    rc = WSAStartup(MAKEWORD(2, 2), &wsa_data);
    if (rc != 0) {
        printf("WSAStartup() error: %d\n", rc);
        goto out_exit;
    }

    // Create a AF_UNIX stream server socket
    server_socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
    if (server_socket_fd == INVALID_SOCKET) {
        printf("socket() error: %d\n", WSAGetLastError());
        goto out_exit;
    }

    socket_addr.sun_family = AF_UNIX;
    strncpy_s(socket_addr.sun_path, sizeof socket_addr.sun_path, SERVER_SOCKET, (sizeof SERVER_SOCKET) - 1);

    // Remove previously created server socket file
    rc = remove(SERVER_SOCKET);
    if (rc != 0) {
        rc = WSAGetLastError();
        if (rc != ENOENT) {
            printf("remove() error: %d\n", rc);
            goto out_exit;
        }
    }

    // Bind the socket to the path
    rc = bind(server_socket_fd, (struct sockaddr *) &socket_addr, sizeof(socket_addr));
    if (rc == SOCKET_ERROR) {
        printf("bind() error: %d\n", WSAGetLastError());
        goto out_exit;
    }

    // Listen to start accepting connections
    rc = listen(server_socket_fd, SOMAXCONN);
    if (rc == SOCKET_ERROR) {
        printf("listen() error: %d\n", WSAGetLastError());
        goto out_exit;
    }

    printf("Accepting connections on: '%s'\n", SERVER_SOCKET);
    // Accept a connection
    client_socket_fd = accept(server_socket_fd, NULL, NULL);
    if (client_socket_fd == INVALID_SOCKET) {
        printf("accept() error: %d\n", WSAGetLastError());
        goto out_exit;
    }
    printf("Accepted a connection.\n" );

    // Send some data
    rc = send(client_socket_fd, send_buf, (int) strlen(send_buf), 0);
    if (rc == SOCKET_ERROR) {
        printf("send() error: %d\n", WSAGetLastError());
        goto out_exit;
    }
    printf("Relayed %zu bytes: '%s'\n", strlen(send_buf), send_buf);

    // Shutdown the connection
    printf("Shutting down\n");
    rc = shutdown(client_socket_fd, 0);
    if (rc == SOCKET_ERROR) {
        printf("shutdown() error: %d\n", WSAGetLastError());
        goto out_exit;
    }

out_exit:
    // Cleanup

    if (server_socket_fd != INVALID_SOCKET) {
        closesocket(server_socket_fd);
    }

    if (client_socket_fd != INVALID_SOCKET) {
        closesocket(client_socket_fd);
    }

    // Analogous to `unlink`
    DeleteFileA(SERVER_SOCKET);

    WSACleanup();

    return 0;
}

client.c

#undef UNICODE

#include <winsock2.h>
#include <windows.h>
#include <ws2tcpip.h>
#include <afunix.h>
#include <stdlib.h>
#include <stdio.h>

#define SERVER_SOCKET "server.sock"

int __cdecl main(void)
{
    SOCKET socket_fd = INVALID_SOCKET;
    int rc = 0;
    char recv_buf[128];
    SOCKADDR_UN socket_addr = { 0 };
    WSADATA wsa_data = { 0 };

    // Initialize Winsock
    rc = WSAStartup(MAKEWORD(2, 2), &wsa_data);
    if (rc != 0) {
        printf("WSAStartup() error: %d\n", rc);
        goto out_exit;
    }

    // Create a AF_UNIX stream server socket
    socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
    if (socket_fd == INVALID_SOCKET) {
        printf("socket() error: %d\n", WSAGetLastError());
        goto out_exit;
    }

    socket_addr.sun_family = AF_UNIX;
    strncpy_s(socket_addr.sun_path, sizeof socket_addr.sun_path, SERVER_SOCKET, (sizeof SERVER_SOCKET) - 1);

    // Connect to the server socket
    rc = connect(socket_fd, (struct sockaddr *) &socket_addr, sizeof(socket_addr));
    if (rc == SOCKET_ERROR) {
        printf("connect() error: %d\n", WSAGetLastError());
        goto out_exit;
    }

    // Receive data from server
    rc = recv(socket_fd, recv_buf, sizeof(recv_buf), 0);
    if (rc < 0) {
        printf("recv() error: %d\n", WSAGetLastError());
        goto out_exit;
    }

    // Print out the received data
    printf("Received data len: %d\n", rc);
    printf("%.*s\n", rc, recv_buf);

out_exit:
    // Cleanup

    if (socket_fd != INVALID_SOCKET) {
        closesocket(socket_fd);
    }

    WSACleanup();

    return 0;
}

Compile and run

https://github.com/niXman/mingw-builds-binaries
https://github.com/mstorsjo/llvm-mingw

https://blogs.msdn.microsoft.com/commandline/2017/12/19/af_unix-comes-to-windows/
https://devblogs.microsoft.com/commandline/windowswsl-interop-with-af_unix/

gcc -Wall server.c -o server -lws2_32
gcc -Wall client.c -o client -lws2_32

$ ./server.exe
Accepting connections on: 'server.sock'
Accepted a connection.
Relayed 21 bytes: 'AF_UNIX from Windows!'
Shutting down

$ ./client.exe
Received data len: 21
AF_UNIX from Windows!