linux的raw socket可以用到DMA吗?如果可以的话,请给个例子
时间: 2023-06-27 22:02:56 浏览: 57
Linux的raw socket可以使用DMA来进行数据传输。下面是一个简单的示例代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/if.h>
#define BUF_SIZE 4096
int main(int argc, char **argv)
{
int sockfd;
char *buffer;
struct ifreq ifr;
struct sockaddr_ll sll;
int ifindex, i, len;
void *mem;
unsigned long mem_size = BUF_SIZE * 2;
// 创建raw socket
sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (sockfd == -1) {
perror("socket");
exit(EXIT_FAILURE);
}
// 获取网卡接口索引
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, "eth0", IFNAMSIZ - 1);
if (ioctl(sockfd, SIOCGIFINDEX, &ifr) == -1) {
perror("ioctl");
close(sockfd);
exit(EXIT_FAILURE);
}
ifindex = ifr.ifr_ifindex;
// 绑定raw socket到网卡接口
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
sll.sll_protocol = htons(ETH_P_ALL);
sll.sll_ifindex = ifindex;
if (bind(sockfd, (struct sockaddr *)&sll, sizeof(sll)) == -1) {
perror("bind");
close(sockfd);
exit(EXIT_FAILURE);
}
// 分配DMA内存
mem = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS | MAP_LOCKED, -1, 0);
if (mem == MAP_FAILED) {
perror("mmap");
close(sockfd);
exit(EXIT_FAILURE);
}
// 设置DMA内存为非缓存区
if (mlock(mem, mem_size) == -1) {
perror("mlock");
munmap(mem, mem_size);
close(sockfd);
exit(EXIT_FAILURE);
}
// 发送数据
buffer = mem;
memset(buffer, 0xff, BUF_SIZE); // 填充数据,这里用0xff代替
len = sendto(sockfd, buffer, BUF_SIZE, 0, (struct sockaddr *)&sll, sizeof(sll));
if (len == -1) {
perror("sendto");
munmap(mem, mem_size);
close(sockfd);
exit(EXIT_FAILURE);
}
// 接收数据
buffer = mem + BUF_SIZE;
len = recvfrom(sockfd, buffer, BUF_SIZE, 0, NULL, NULL);
if (len == -1) {
perror("recvfrom");
munmap(mem, mem_size);
close(sockfd);
exit(EXIT_FAILURE);
}
// 打印接收到的数据
printf("Received %d bytes:\n", len);
for (i = 0; i < len; i++) {
printf("%02x ", buffer[i]);
if ((i + 1) % 16 == 0)
printf("\n");
}
printf("\n");
// 释放DMA内存
munmap(mem, mem_size);
// 关闭raw socket
close(sockfd);
return 0;
}
```
这个例子中,我们首先创建了一个raw socket,并绑定到网卡接口上。然后使用mmap函数分配了一个大小为2倍BUF_SIZE的DMA内存,并将其设置为非缓存区,最后分别发送和接收数据。需要注意的是,使用DMA内存时需要小心,因为它不受内核的保护,可能会导致系统崩溃。建议在使用DMA内存时仔细测试和验证。