Milind can you help Thierry on this.
On Wed, Apr 8, 2009 at 7:14 PM, Thierry <chocapiiic.tiery@xxxxxxxxx> wrote:
> Hi,
>
> I want to use netlink socket between kernel and userspace in order to
> get some information from kernel code.
> I use netlink_broadcast function in order to send information to a
> specific group, and my user-level code connect to this socket with the
> correct groupId but doesn't receive anythings.
> Everythings works when I use netlink_unicast.
>
> I use centos5.2, kernel 2.6.18-92.1.22
>
> If someone can help me...
>
> Thierry
>
>
>
>
>
> ---------------------------
>
> kernel-code:
>
> #include <linux/config.h>
> #include <linux/socket.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/netlink.h>
> #include <net/sock.h>
> //#include <net/netlink.h>
>
> #define NETLINK_IB 24
> #define MAX_PAYLOAD 1024
> #define GROUP_IB 59
>
> static struct sock *nl_sk = NULL;
>
> static void nl_ib_data_ready (struct sock *sk, int len)
> {
> wake_up_interruptible(sk->sk_sleep);
> }
>
> static void netlink_ib_open()
> {
> struct sk_buff *skb = NULL;
> struct nlmsghdr *nlh = NULL;
> int err;
> u32 pid;
>
> //Creation de la netlink socket <=> socket()
> nl_sk = netlink_kernel_create(NETLINK_IB, GROUP_IB, nl_ib_data_ready,
> THIS_MODULE);
>
> skb = alloc_skb(NLMSG_SPACE(MAX_PAYLOAD),GFP_KERNEL);
> nlh = (struct nlmsghdr *)skb->data;
>
> nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
> nlh->nlmsg_pid = 0; //Depuis le noyau
> nlh->nlmsg_flags = 0;
>
> strcpy(NLMSG_DATA(nlh), "Message du kernel =(");
> NETLINK_CB(skb).pid = 0;
> NETLINK_CB(skb).dst_pid = 0; //Multicast
> NETLINK_CB(skb).dst_group = GROUP_IB;
>
> //Envoi des donnees
> printk( KERN_ALERT "j'envoi els donnees\n");
> netlink_broadcast(nl_sk, skb, 0, GROUP_IB, GFP_KERNEL);
> sock_release(nl_sk->sk_socket);
> }
>
> static int __init netlink_ib_module_init(void)
> {
> printk(KERN_INFO "netlink_ib module: Initialisation de la Netlink Socket\n");
> netlink_ib_open();
> return 0;
> }
>
> static void __exit netlink_ib_module_exit(void)
> {
> printk(KERN_INFO "Dechargement de netlink_ib module\n");
> }
>
> MODULE_DESCRIPTION("Kernel/User socket for IB support");
> module_init(netlink_ib_module_init);
> module_exit(netlink_ib_module_exit);
>
> ----------------------------
>
> and the user-level code:
>
> #include <sys/socket.h>
> #include <linux/netlink.h>
> #define NETLINK_IB 24
> #define GROUP_IB 59
>
> #define MAX_PAYLOAD 1024
>
> struct sockaddr_nl src_addr, dst_addr;
> struct nlmsghdr *nlh = NULL;
> struct msghdr msg;
> struct iovec iov;
> int sock_fd;
>
>
> int main()
> {
> /* Ouverture de la socket Netlink*/
> sock_fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_IB);
>
> memset(&src_addr, 0, sizeof(src_addr));
> src_addr.nl_family = AF_NETLINK;
> src_addr.nl_pid = getpid();
> src_addr.nl_groups = GROUP_IB; // Multicast
> bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr));
>
> memset(&dst_addr, 0, sizeof(dst_addr));
> nlh = (struct nlhmsghdr *)malloc(NLMSG_SPACE(MAX_PAYLOAD));
> memset(nlh, 0, NLMSG_SPACE(MAX_PAYLOAD));
>
> iov.iov_base = (void *)nlh;
> iov.iov_len = nlh->nlmsg_len;
> msg.msg_name = (void *)&dst_addr;
> msg.msg_namelen = sizeof(dst_addr);
> msg.msg_iov = &iov;
> msg.msg_iovlen = 1;
>
> printf("On ecoute...\n");
> /* On ecoute ce que le kernel renvoi */
> recvmsg(sock_fd, &msg, 0);
> printf("jai recu");
> char * truc = NLMSG_DATA(nlh);
> printf("Message recu dans lespace utilisateur: %s\n", truc);
> close(sock_fd);
>
> return 0;
>
> }
>
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>
--
Regards,
Sandeep.
“To learn is to change. Education is a process that changes the learner.”
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