Init with small code example

user/main.c

@@ -0,0 +1,61 @@
+
+#include <sys/socket.h>
+#include <linux/netlink.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#define NETLINK_USER 30
+
+#define MAX_PAYLOAD 1024 /* maximum payload size*/
+
+int main()
+{
+
+struct sockaddr_nl src_addr, dest_addr;
+struct nlmsghdr *nlh = NULL;
+struct iovec iov;
+int sock_fd;
+struct msghdr msg;
+
+
+sock_fd=socket(PF_NETLINK, SOCK_RAW, NETLINK_USER);
+if(sock_fd<0)
+return -1;
+
+memset(&src_addr, 0, sizeof(src_addr));
+src_addr.nl_family = AF_NETLINK;
+src_addr.nl_pid = getpid(); /* self pid */
+
+bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr));
+
+memset(&dest_addr, 0, sizeof(dest_addr));
+memset(&msg, 0, sizeof(msg));
+dest_addr.nl_family = AF_NETLINK;
+dest_addr.nl_pid = 0; /* For Linux Kernel */
+dest_addr.nl_groups = 0; /* unicast */
+
+nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(MAX_PAYLOAD));
+memset(nlh, 0, NLMSG_SPACE(MAX_PAYLOAD));
+nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
+nlh->nlmsg_pid = getpid();
+nlh->nlmsg_flags = 0;
+
+strcpy(NLMSG_DATA(nlh), "Hello");
+
+iov.iov_base = (void *)nlh;
+iov.iov_len = nlh->nlmsg_len;
+msg.msg_name = (void *)&dest_addr;
+msg.msg_namelen = sizeof(dest_addr);
+msg.msg_iov = &iov;
+msg.msg_iovlen = 1;
+
+printf("Sending message to kernel\n");
+sendmsg(sock_fd,&msg,0);
+printf("Waiting for message from kernel\n");
+
+/* Read message from kernel */
+recvmsg(sock_fd, &msg, 0);
+printf("Received message payload: %s\n", (char *)NLMSG_DATA(nlh));
+close(sock_fd);
+}