Hi,
I have tried to change groupId, with different value, but there should
be somethings wrong: the userspace prgm doesn't receive message.
I would like to know if there is a plugin for tcpdump or an way of
capture trafic on netlink socket, just like usual network socket in
order to see were is my problem: in kernel space code or userspace
code.
My program code is attached, with english commit (sorry for last mail).
I have also tried my code on differents kernel (redhat 4.4 with kernel
2.6.9-42.ELsmp, centos52 kernel 2.6.18-92.1.22).
If there is other ways to send information from kernel space to user space...
My aim is to capture data trafic from infiniband and dump trafic, for
example in a netlink socket. Then I will be able with a userspace code
to translate informations in .cap files.
Thats why I think netlink_broadcast is a good idea.
I will be always looking at kernelnewbie mailinglsit for several month,
Regards,
Thierry
--------------
kernel-level 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>
#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;
//Socket_create
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; //from kernel
nlh->nlmsg_flags = 0;
strcpy(NLMSG_DATA(nlh), "Message from kernel ");
NETLINK_CB(skb).pid = 0;
NETLINK_CB(skb).dst_pid = 0; //Multicast
NETLINK_CB(skb).dst_group = GROUP_IB;
//data send
printk( KERN_ALERT "data sent\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: Init\n");
netlink_ib_open();
return 0;
}
static void __exit netlink_ib_module_exit(void)
{
printk(KERN_INFO "Unloading netlink_ib module\n");
}
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Kernel/User socket for IB support");
module_init(netlink_ib_module_init);
module_exit(netlink_ib_module_exit);
------------------
userlevel 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()
{
/* Socket create*/
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("Listenning on netlink socket...\n");
recvmsg(sock_fd, &msg, 0);
printf("Message received in userspace: %s\n", NLMSG_DATA(nlh));
close(sock_fd);
return 0;
}
-----------
On Wed, Apr 8, 2009 at 5:51 PM, Sandeep K Sinha <[email protected]> wrote:
> Milind can you help Thierry on this.
>
>
> On Wed, Apr 8, 2009 at 7:14 PM, Thierry <[email protected]> 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;
>>
>> }
>>
>> --
>> To unsubscribe from this list: send an email with
>> "unsubscribe kernelnewbies" to [email protected]
>> Please read the FAQ at http://kernelnewbies.org/FAQ
>>
>>
>
>
>
> --
> Regards,
> Sandeep.
>
>
>
>
>
>
> “To learn is to change. Education is a process that changes the learner.”
>
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