我对此TPACKET_V2的用法有疑问.
我的问题是,在套接字上设置了这种类型的数据包之后,当我尝试接收一些数据包时,我无法从数据包(当然是从数据包的标头)读取vlan ID,vlan_tci永远为0.
现在,我使用的是开放式suse sp1,当我在sless sp2上运行程序时,我可以使用在sless sp1上不起作用的同一程序获取vlan id,但奇怪的是tcpdump能够获取VLAN ID(在此基础上)和tcpdump设置了TPACKET_V2(因此这意味着支持TPACKET_2)
我的简单项目基于这些函数,全部由函数createSocket调用,然后有一个简单的方法正在读取套接字上的数据包,在那里我尝试获取有关vlan id的信息(之前还有与TPACKET_V1)
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <netinet/ether.h>
#include <linux/filter.h>
#include <net/if.h>
#include <arpa/inet.h>
enum INTERFACE_T
{
RX_INTERFACE,
TX_INTERFACE
};
static const char* PKT_TYPE[];
// BLOCK_NUM*BLOCK_SIZE = FRAME_NUM*FRAME_SIZE
enum { RX_BLOCK_SIZE = 8192,
RX_BLOCK_NUM = 256,
RX_FRAME_SIZE = 2048,
RX_FRAME_NUM = 1024
};
enum { TX_BLOCK_SIZE = 8192,
TX_BLOCK_NUM = 256,
TX_FRAME_SIZE = 2048,
TX_FRAME_NUM = 1024
};
struct RxFrame {
struct tpacket2_hdr tp_h; // Packet header
uint8_t tp_pad[TPACKET_ALIGN(sizeof(tpacket2_hdr))-sizeof(tpacket2_hdr)];
struct sockaddr_ll sa_ll; // Link level address information
uint8_t sa_ll_pad[14]; //Alignment padding
struct ethhdr eth_h;
} __attribute__((packed));
struct TxFrame
{
struct tpacket_hdr tp_h; // Packet header
uint8_t tp_pad[TPACKET_ALIGN(sizeof(tpacket_hdr))-sizeof(tpacket_hdr)];
// struct vlan_ethhdr vlan_eth_h;
// struct arp arp;
} __attribute__((packed));
struct ring_buff {
struct tpacket_req req;
size_t size; // mmap size
size_t cur_frame;
struct iovec *ring_buffer_;
void *buffer; // mmap
};
int setIfFlags(short int flags)
{
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, if_name_.c_str(), sizeof(ifr.ifr_name));
ifr.ifr_hwaddr.sa_family=getIfArptype();
ifr.ifr_flags |= flags;
if ( ioctl(socket_, SIOCSIFFLAGS, &ifr) == -1)
{
std::cout << "Error: ioctl(SIOSIFFLAGS) failed!" << std::endl;
return 1;
}
return 0;
}
int bindSocket()
{
struct sockaddr_ll sll;
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
sll.sll_protocol = htons(ETH_P_ALL);
sll.sll_ifindex = ifIndex_;
sll.sll_hatype = 0;
sll.sll_pkttype = 0;
sll.sll_halen = 0;
if (bind(socket_, (struct sockaddr *)&sll, sizeof(sll)) < 0) {
std::cout << "Error: bind() failed!" << std::endl;
return 1;
}
return 0;
}
int packetMmap(ring_buff * rb)
{
assert(rb);
rb->buffer = mmap(0, rb->size, PROT_READ | PROT_WRITE, MAP_SHARED, socket_, 0);
if (rb->buffer == MAP_FAILED) {
std::cout << "Error: mmap() failed!" << std::endl;
return 1;
}
return 0;
}
void packetMunmap(ring_buff * rb)
{
assert(rb);
if (rb->buffer)
{
munmap(rb->buffer, rb->size);
rb->buffer = NULL;
rb->size = 0;
}
}
int frameBufferCreate(ring_buff * rb)
{
assert(rb);
rb->ring_buffer_ = (struct iovec*) malloc(rb->req.tp_frame_nr * sizeof(*rb->ring_buffer_));
if (!rb->ring_buffer_) {
std::cout << "No memory available !!!" << std::endl;
return 1;
}
memset(rb->ring_buffer_, 0, rb->req.tp_frame_nr * sizeof(*rb->ring_buffer_));
for (unsigned int i = 0; i < rb->req.tp_frame_nr; i++) {
rb->ring_buffer_[i].iov_base = static_cast<void *>(static_cast<char *>(rb->buffer)+(i*rb->req.tp_frame_size));
rb->ring_buffer_[i].iov_len = rb->req.tp_frame_size;
}
return 0;
}
void setRingBuffer(struct ring_buff *ringbuf) { rb_ = ringbuf; }
int setVlanTaggingStripping()
{
socklen_t len;
int val;
unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff;
unsigned int tp_hdr_len;
unsigned int frame_size = RX_FRAME_SIZE;
val = TPACKET_V2;
len = sizeof(val);
if (getsockopt(socket_, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) {
std::cout << "Error: getsockopt(SOL_PACKET, PACKET_HDRLEN) failed (can't get TPACKET_V2 header len on packet)" << std::endl;
return 1;
}
tp_hdr_len = val;
std::cout << "TPACKET_V2 header is supported (hdr len is " << val << ")"<< std::endl;
std::cout << "tpacket2_hdrs header is supported (hdr len is " << sizeof(tpacket2_hdr) << ")"<< std::endl;
val = TPACKET_V2;
if (setsockopt(socket_, SOL_PACKET, PACKET_VERSION, &val, sizeof(val)) < 0) {
std::cout << "Error: setsockopt(SOL_PACKET, PACKET_VERSION) failed (can't activate TPACKET_V2 on packet)" << std::endl;
return 1;
}
std::cout << "TPACKET_V2 version is configured !!! " << std::endl;
/* Reserve space for VLAN tag reconstruction */
val = VLAN_TAG_LEN;
if (setsockopt(socket_, SOL_PACKET, PACKET_RESERVE, &val, sizeof(val)) < 0) {
std::cout << "Error: setsockopt(SOL_PACKET, PACKET_RESERVE) failed (can't set up reserve on packet)" << std::endl;
return 1;
}
std::cout<< "Reserve space for VLAN tag reconstruction is configured !!! " << std::endl;
return 0;
}
int setSoBufforce(int optname, int buffSize)
{
if (setsockopt(socket_, SOL_SOCKET, SO_SNDBUFFORCE, &buffSize, sizeof(buffSize)) == -1)
{
std::cout << "Error: setsocketopt("<< (optname == SO_SNDBUFFORCE ? "SO_SNDBUFFORCE" : "SO_RCVBUFFORCE") << ") failed!" << std::endl;
return 1;
}
return 0;
}
createSocket(std::string ifName, INTERFACE_T ifType)
{
if (ifName.empty())
{
std::cout << "Error: interface is empty!" << std::endl;;
return NULL;
}
//Create the socket
if ( (socket_ = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) == -1 )
{
std::cout << "Error: calling socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)) failed!" << std::endl;
}
std::cout << "Creating Socket on interface= " << ifName << " to listen to ETH_P_ALL"<<std::endl;;
s->setIfFlags(IFF_PROMISC|IFF_BROADCAST);
//allocate space for ring buffer
ring_buff *rb = (ring_buff *) malloc(sizeof(ring_buff));
// use the same size for RX/TX ring
//set the version , here I insert the use of TPACKET_V2!
setVlanTaggingStripping();
rb->req.tp_block_size = RX_BLOCK_SIZE;
rb->req.tp_block_nr = RX_BLOCK_NUM;
rb->req.tp_frame_size = RX_FRAME_SIZE;
rb->req.tp_frame_nr = RX_FRAME_NUM;
setPacketRing(PACKET_RX_RING,&rb->req);
rb->size = (rb->req.tp_block_size)*(rb->req.tp_block_nr);
rb->cur_frame = 0;
// Tweak send/rcv buffer size
int sndBufSz = 4194304; // Send buffer in bytes
int rcvBufSz = 4194304; // Receive buffer in bytes
if (setSoBufforce(SO_SNDBUFFORCE, sndBufSz))
{
//close socket
}
if (setSoBufforce(SO_RCVBUFFORCE, rcvBufSz))
{
//close socket
}
// Add ARP filter so we will only receive ARP packet on this socket
struct sock_filter BPF_code[6];
struct sock_fprog filter;
bindSocket();
if (packetMmap(rb))
{
std::cout << "Error: mmap() failed!" << std::endl;
//close socket
}
frameBufferCreate(rb);
setRingBuffer(rb);
}
在我的接收数据包功能中,我尝试从中读取信息,尤其是h_vlan_TCI,但我收到的都是0x00！有什么建议么？
struct vlan_ethhdr* vlan_eth_h = (struct vlan_ethhdr*)&frame->eth_h
void readRawSocket(socket_)
{
while (*(unsigned long*)rb->ring_buffer_[rb->cur_frame].iov_base)
{
RxFrame* frame = (RxFrame *)rb->ring_buffer_[rb->cur_frame].iov_base;
#if 0
tpacket_hdr* h = &frame->tp_h;
char buffer[256];
sprintf (buffer, " -tpacket(v1): status=%ld,len=%d,snaplen=%d,mac=%d,net=%d,sec=%d,usec=%d",
h->tp_status, h->tp_len, h->tp_snaplen, h->tp_mac,h->tp_net, h->tp_sec, h->tp_usec);
std::cout << std::string(buffer) << std::endl;
#else
tpacket2_hdr* h = &frame->tp_h;
char buffer[512];
sprintf (buffer, " -tpacket(v2): status=%d,len=%d,snaplen=%d,mac=%d,net=%d,sec=%d,nsec=%d,vlan_tci=%d (vlan_tci=0x%04x)",
h->tp_status, h->tp_len, h->tp_snaplen, h->tp_mac, h->tp_net, h->tp_sec, h->tp_nsec, h->tp_vlan_tci, ntohs(h->tp_vlan_tci));
std::cout << std::string(buffer) << std::endl;
#endif
if ( ETH_P_8021Q == ntohs(frame->eth_h.h_proto) )
{
struct vlan_ethhdr* vlan_eth_h = (struct vlan_ethhdr*)&frame->eth_h;
int vlan_tag = VLAN_TAG(ntohs(vlan_eth_h->h_vlan_TCI));
std::cout << " -Vlan " << vlan_tag << " packet to this host received";
}
rb->cur_frame = ( rb->cur_frame+1) % rx_socket_->getFrameNum();
} // while()
}
解决方法:
当内核删除VLAN时,它还将eth_h.h_proto更改为de vlan标记后的协议,因此ETH_P_8021Q == ntohs(frame-> eth_h.h_proto)很可能为假.
另外,如果您在标记的接口(即eth0.100)而不是物理接口(eth0)中进行侦听,则不会看到标签.