Multikernel Vsock Test (Server)

mk_vsock_server.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/socket.h>
#include <linux/vm_sockets.h>

#define VSOCK_TRANSPORT_VM          0
#define VSOCK_TRANSPORT_MULTIKERNEL 1
#define SO_VM_SOCKETS_TRANSPORT     9

int main(int argc, char *argv[])
{
	int listen_fd, conn_fd;
	struct sockaddr_vm sa_listen, sa_client;
	socklen_t sa_client_len;
	int port = 9000;
	int transport_type = VSOCK_TRANSPORT_MULTIKERNEL;
	char buffer[1024];
	ssize_t n;

	if (argc > 1) {
		port = atoi(argv[1]);
	}

	printf("Multikernel vsock server starting on port %d\n", port);

	/* Create vsock socket */
	listen_fd = socket(AF_VSOCK, SOCK_STREAM, 0);
	if (listen_fd < 0) {
		perror("socket");
		return 1;
	}

	/* Set transport to multikernel */
	if (setsockopt(listen_fd, AF_VSOCK, SO_VM_SOCKETS_TRANSPORT,
		       &transport_type, sizeof(transport_type)) < 0) {
		perror("setsockopt(SO_VM_SOCKETS_TRANSPORT)");
		close(listen_fd);
		return 1;
	}
	printf("Transport set to MULTIKERNEL\n");

	/* Bind to any CID, specific port */
	memset(&sa_listen, 0, sizeof(sa_listen));
	sa_listen.svm_family = AF_VSOCK;
	sa_listen.svm_cid = VMADDR_CID_ANY;
	sa_listen.svm_port = port;

	if (bind(listen_fd, (struct sockaddr *)&sa_listen, sizeof(sa_listen)) < 0) {
		perror("bind");
		close(listen_fd);
		return 1;
	}
	printf("Bound to port %d\n", port);

	/* Listen */
	if (listen(listen_fd, 5) < 0) {
		perror("listen");
		close(listen_fd);
		return 1;
	}
	printf("Listening for connections...\n");

	/* Accept connections */
	while (1) {
		sa_client_len = sizeof(sa_client);
		conn_fd = accept(listen_fd, (struct sockaddr *)&sa_client, &sa_client_len);
		if (conn_fd < 0) {
			perror("accept");
			continue;
		}

		printf("Connection from CID %u, port %u\n",
		       sa_client.svm_cid, sa_client.svm_port);

		/* Echo server */
		while ((n = recv(conn_fd, buffer, sizeof(buffer), 0)) > 0) {
			printf("Received %zd bytes: %.*s\n", n, (int)n, buffer);
			
			if (send(conn_fd, buffer, n, 0) != n) {
				perror("send");
				break;
			}
		}

		if (n < 0) {
			perror("recv");
		}

		printf("Connection closed\n");
		close(conn_fd);
	}

	close(listen_fd);
	return 0;
}