学步园

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/workqueue.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/socket.h>
#include <net/sock.h>

static struct socket *sock;
static struct work_struct work;

static int udp_sendto(struct socket *sock, void * buff, size_t len,
unsigned flags, struct sockaddr *addr, int addr_len)
{
struct kvec vec;
struct msghdr msg;
vec.iov_base=buff;
vec.iov_len=len;

memset(&msg, 0x00, sizeof(msg));
msg.msg_name=addr;
msg.msg_namelen=addr_len;
msg.msg_flags = flags | MSG_DONTWAIT;
return kernel_sendmsg(sock, &msg, &vec, 1, len);
}

static char buffer[128];

static void sendmsg(void *dummy)
{
int n;
struct sockaddr_in addr;
memset(&addr, 0x00, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(1000);
addr.sin_addr.s_addr = in_aton("61.139.2.69");
n = udp_sendto(sock, buffer, 128, 0, (struct sockaddr *)&addr,
sizeof(addr));
printk("send %i bytes\n", n);
}

static int socket_init(void)
{
INIT_WORK(&work, sendmsg, NULL);
sock_create_kern(PF_INET, SOCK_DGRAM, 0, &sock);
schedule_work(&work);
return 0;
}

static void socket_exit(void)

{
sock_release(sock);
}

module_init(socket_init);

module_exit(socket_exit);

上面的例子2.6内核可以用，2.4的内核好像只能自己构造2,3,4层的头，然后用dev_qu
eue_xmit。

用sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock)
创建socket结构.
用kernel_sendmsg(sock, &msg, &vec, x, xxx)发送数据包,
内核态的bsd socket和用户态的socket基本相同, 不过内核态用socket结构, 用户态用文件描述符, 内核的bind/connect/listen函数都用socket->ops->bind/connect/listen... 等, 发包和收包用kernel_sendmsg和kernel_recvmsg, 不过注意, kernel用kvec, 用户态用iovec, 不过他们可以相互转换. 用sourcenavigator看packetgen.c(一个内核发包模块)就明白了.

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/workqueue.h>
#include <linux/timer.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/socket.h>
#include <net/sock.h>

struct socket *sock;

unsigned char buffer[10]=
{ 1,2,3,4,5,6,7,8,9,0,
};

static int ker_send_udp(char* ip_addr, unsigned char * data, size_t len )
{
int ret;

u32 remote_ip = ntohl(in_aton(ip_addr));

struct sockaddr_in sin = {
.sin_family = AF_INET,
.sin_port = htons(65530),
.sin_addr = {.s_addr = remote_ip}
};

struct kvec iov = {.iov_base = (void *)data, .iov_len = len};
struct msghdr udpmsg;

udpmsg.msg_name = (void *)&sin;
udpmsg.msg_namelen = sizeof(sin);
udpmsg.msg_control = NULL;
udpmsg.msg_controllen = 0;
udpmsg.msg_flags=0;

ret = kernel_sendmsg(sock, &udpmsg, &iov, 1, len);
printk("rets = %d\n",ret);

return 0;
}

static int socket_init (void)
{
int ret;
ret = sock_create_kern (PF_INET, SOCK_DGRAM,IPPROTO_UDP, &sock);
printk("retc = %d\n",ret);

ker_send_udp("192.168.1.253", buffer, 10);
return 0;
}

static void socket_exit (void)
{
sock_release (sock);
}

module_init (socket_init);
module_exit (socket_exit);
MODULE_LICENSE ("GPL");