#include
#include
#include
#include
#include
#include /* the L2 protocols */
void CallBackPacket(char *data)
{
printf("Recv A Packet.\n");
}
int main()
{
int fd = 0, ret = 0;
char *buff = NULL;
//fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
//可以使用ARP进行一下测试
fd = socket(PF_PACKET, SOCK_DGRAM, htons (ETH_P_ARP));
if(fd<0)
{
perror("socket");
goto failed_2;
}
//PACKET_VERSION和SO_BINDTODEVICE可以省略
#if 0
const int tpacket_version = TPACKET_V1;
/* set tpacket hdr version. */
ret = setsockopt(fd, SOL_PACKET, PACKET_VERSION, &tpacket_version, sizeof (int));
if(ret<0)
{
perror("setsockopt");
goto failed_2;
}
//#define NETDEV_NAME "wlan0"
#define NETDEV_NAME "eth0"
/* bind to device. */
ret = setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, NETDEV_NAME, sizeof (NETDEV_NAME));
if(ret<0)
{
perror("setsockopt");
goto failed_2;
}
#endif
struct tpacket_req req;
#define PER_PACKET_SIZE 2048
const int BUFFER_SIZE = 1024*1024*16; //16MB的缓冲区
req.tp_block_size = 4096;
req.tp_block_nr = BUFFER_SIZE/req.tp_block_size;
req.tp_frame_size = PER_PACKET_SIZE;
req.tp_frame_nr = BUFFER_SIZE/req.tp_frame_size;
ret = setsockopt(fd, SOL_PACKET, PACKET_RX_RING, (void *)&req, sizeof(req));
if(ret<0)
{
perror("setsockopt");
goto failed_2;
}
buff = (char *)mmap(0, BUFFER_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if(buff == MAP_FAILED)
{
perror("mmap");
goto failed_2;
}
int nIndex=0, i=0;
while(1)
{
//这里在poll前先检查是否已经有报文被捕获了
struct tpacket_hdr* pHead = (struct tpacket_hdr*)(buff+ nIndex*PER_PACKET_SIZE);
//如果frame的状态已经为TP_STATUS_USER了，说明已经在poll前已经有一个数据包被捕获了，如果poll后不再有数据包被捕获，那么这个报文不会被处理，这就是所谓的竞争情况。
if(pHead->tp_status == TP_STATUS_USER)
goto process_packet;
//poll检测报文捕获
struct pollfd pfd;
pfd.fd = fd;
//pfd.events = POLLIN|POLLRDNORM|POLLERR;
pfd.events = POLLIN;
pfd.revents = 0;
ret = poll(&pfd, 1, -1);
if(ret<0)
{
perror("poll");
goto failed_1;
}
process_packet:
//尽力的去处理环形缓冲区中的数据frame，直到没有数据frame了
for(i=0; i
{
struct tpacket_hdr* pHead = (struct tpacket_hdr*)(buff+ nIndex*PER_PACKET_SIZE);
//XXX: 由于frame都在一个环形缓冲区中，因此如果下一个frame中没有数据了，后面的frame也就没有frame了
if(pHead->tp_status == TP_STATUS_KERNEL)
break;
//处理数据frame
CallBackPacket((char*)pHead+pHead->tp_net);
//重新设置frame的状态为TP_STATUS_KERNEL
pHead->tp_len = 0;
pHead->tp_status = TP_STATUS_KERNEL;
//更新环形缓冲区的索引，指向下一个frame
nIndex++;
nIndex%=req.tp_frame_nr;
}
}
success:
close(fd);
munmap(buff, BUFFER_SIZE);
return 0;
failed_1:
munmap(buff, BUFFER_SIZE);
failed_2:
close(fd);
return -1;
}
