Multikernel Vsock Test (Client)

mk_vsock_client.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 sock_fd;
	struct sockaddr_vm sa;
	int cid, port;
	int transport_type = VSOCK_TRANSPORT_MULTIKERNEL;
	char send_buf[256];
	char recv_buf[256];
	ssize_t n;

	if (argc < 3) {
		fprintf(stderr, "Usage: %s <instance_cid> <port>\n", argv[0]);
		fprintf(stderr, "Example: %s 0 9000  (connect to instance 0, port 9000)\n", argv[0]);
		return 1;
	}

	cid = atoi(argv[1]);
	port = atoi(argv[2]);

	printf("Connecting to multikernel instance %d, port %d\n", cid, port);

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

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

	/* Connect to server */
	memset(&sa, 0, sizeof(sa));
	sa.svm_family = AF_VSOCK;
	sa.svm_cid = cid;
	sa.svm_port = port;

	if (connect(sock_fd, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
		perror("connect");
		close(sock_fd);
		return 1;
	}
	printf("Connected successfully!\n");

	/* Interactive client */
	printf("Enter messages (Ctrl-D to quit):\n");
	while (fgets(send_buf, sizeof(send_buf), stdin) != NULL) {
		size_t len = strlen(send_buf);
		
		/* Send message */
		if (send(sock_fd, send_buf, len, 0) != len) {
			perror("send");
			break;
		}
		printf("Sent %zu bytes\n", len);

		/* Receive echo */
		n = recv(sock_fd, recv_buf, sizeof(recv_buf), 0);
		if (n < 0) {
			perror("recv");
			break;
		}
		if (n == 0) {
			printf("Server closed connection\n");
			break;
		}

		printf("Received echo (%zd bytes): %.*s", n, (int)n, recv_buf);
	}

	close(sock_fd);
	printf("Connection closed\n");
	return 0;
}