네트워크 프로그래밍 : connection Time 얻어오기

if (tcp 패킷이라면)
{
	if (tcp.syn == 1)	
	{
		connection 구조체에, time, port, ip, seq를 설정한다.
	}
	else
	{
		port와 ip가 동일하고 seq == seq+1 이라면
		연결이 완성된 것이다.
		connection 시간 = current time = time;
	}
}

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

// Unix Standard Library
#include <time.h>
#include <unistd.h>
#include <stdlib.h>

#include <iostream>

#include <pcap.h>

#include <net/bpf.h>
#include <netinet/in.h>

#include <stdio.h>
#include <stdlib.h>

#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/if_ether.h>
#include <netinet/in.h>

#include <net/if.h>
#include <net/ethernet.h>
#include <arpa/inet.h>

#include <sys/socket.h>


#define TCPHEADERSIZE 6*4

using namespace std;

enum MODE{NONPROMISCUOUS, PROMISCOUS};

struct _connect_Info
{
  struct timeval start_Time;
  int flag;
};
int main(int argc, char *argv[])
{
  char errbuf[256];
  int ret;
  struct _connect_Info  *connect_Info;

  bpf_u_int32 netp;
  bpf_u_int32 maskp;

  char *dev;

  struct pcap_pkthdr hdr;
  struct ether_header *ep;
  struct tcphdr    *tcph;
  struct ip *iph;

  struct timeval current_time;

  struct sockaddr_in *sin;

  const u_char *packet;

  unsigned short ether_type;
  pcap_t *pcd;

  // 65536개 만큼의 Src Port를 저장할 수 있는 자료공간을 만든다.
  connect_Info = (struct _connect_Info *)malloc(sizeof(struct _connect_Info) * 65536);

  dev = pcap_lookupdev(errbuf);
  if (dev == NULL)
  {
    printf("%s\n", errbuf);
    return 1;
  }

  // Non Promiscous 모드로 이더넷 장치를 연다.
  pcd = pcap_open_live(dev, BUFSIZ, NONPROMISCUOUS, -1, errbuf);
  if (pcd == NULL)
  {
    printf("%s\n", errbuf);
    return 1;
  }

  // 패킷을 읽어들인다.
  for (;packet=(const unsigned char *)pcap_next(pcd, &hdr);)
  {
    ep = (struct ether_header *)packet;
    packet += sizeof(struct ether_header);
    ether_type = ntohs(ep->ether_type);
    // TCP/IP 패킷인 경우에만 분석한다.
    if (ether_type == ETHERTYPE_IP)
    {
      iph = (struct ip *)packet;
      if(iph->ip_p == IPPROTO_TCP)
      {
        tcph = (struct tcphdr *)(packet + iph->ip_hl *4);
        // syn 이 1일경우
        if (tcph->syn == 1)
        {
          gettimeofday(&current_time, NULL);
          // ACK_SEQ가 0이면 connection 시도다.
          if (tcph->ack_seq == 0)
          {
            memcpy((void *)&connect_Info[ntohs(tcph->source)].start_Time,
              (void *)&current_time, sizeof(struct timeval)) ;
            connect_Info[ntohs(tcph->source)].flag = 1;
          }
          // 그렇지 않을 경우 Server에서 Client로의 ACK다.
          else
          {
            if (connect_Info[ntohs(tcph->dest)].flag == 1)
            {
              connect_Info[ntohs(tcph->dest)].flag = 2;
            }
          }
        }
        // 연결이 맺어졌다.
        if (connect_Info[ntohs(tcph->source)].flag == 2)
        {
          printf("%d -> %d\n", ntohs(tcph->source), ntohs(tcph->dest));
          printf("Connection Time %.4f msec\n",
              (current_time.tv_sec - connect_Info[ntohs(tcph->source)].start_Time.tv_sec)*1000 +
              (float)(current_time.tv_usec - connect_Info[ntohs(tcph->source)].start_Time.tv_usec)/1000.0);
              memset((void *)&connect_Info[ntohs(tcph->source)], 0x00, sizeof(struct _connect_Info));
          printf("=========\n");
        }
      }
    }
  }
  return EXIT_SUCCESS;

}

# ./con_time
35512 -> 80
Connection Time 0.0180 msec
=========
49187 -> 80
Connection Time 0.0260 msec
=========
2564 -> 80
Connection Time 0.0200 msec
=========
2565 -> 80
Connection Time 0.0040 msec
=========
2567 -> 80
Connection Time 0.0040 msec
=========
51374 -> 80
Connection Time 0.0240 msec
=========
2568 -> 80
Connection Time 0.0050 msec
=========
62272 -> 80
Connection Time 0.0260 msec
=========
65186 -> 80
Connection Time 0.0240 msec
=========
52408 -> 80
Connection Time 0.0210 msec
=========