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Ubuntu下GCC之libpcap庫數據庫通信協議解析基礎框架代碼

Ubuntu下GCC之libpcap庫數據庫通信協議解析基礎框架代碼:

/*
 * dbaudit.c
 *
 * dbaudit example of TCP/IP packet capture using libpcap.
 *
 * Version 0.1 (2011-09-20)
 * Copyright (c) 2011 The dbaudit Group
 *
 * This software is intended to be used as a practical example and
 * demonstration of the libpcap library; available at:
 * http://www.linuxidc.com/
 *
 ****************************************************************************
 *
 * Example compiler command-line for GCC:
 *   gcc -Wall -o dbaudit dbaudit.c -lpcap
 *
 ****************************************************************************
 *
 * Code Comments
 *
 * This section contains additional information and explanations regarding
 * comments in the source code. It serves as documentaion and rationale
 * for why the code is written as it is without hindering readability, as it
 * might if it were placed along with the actual code inline. References in
 * the code appear as footnote notation (e.g. [1]).
 *
 * 1. Ethernet headers are always exactly 14 bytes, so we define this
 * explicitly with "#define". Since some compilers might pad structures to a
 * multiple of 4 bytes - some versions of GCC for ARM may do this -
 * "sizeof (struct sniff_ethernet)" isn't used.
 *
 * 2. Check the link-layer type of the device that's being opened to make
 * sure it's Ethernet, since that's all we handle in this example. Other
 * link-layer types may have different length headers (see [1]).
 *
 * 3. This is the filter expression that tells libpcap which packets we're
 * interested in (i.e. which packets to capture). Since this source example
 * focuses on IP and TCP, we use the expression "ip", so we know we'll only
 * encounter IP packets. The capture filter syntax, along with some
 * examples, is documented in the tcpdump man page under "expression."
 * Below are a few simple examples:
 *
 * Expression   Description
 * ----------   -----------
 * ip    Capture all IP packets.
 * tcp    Capture only TCP packets.
 * tcp port 80   Capture only TCP packets with a port equal to 80.
 * ip host 10.1.2.3  Capture all IP packets to or from host 10.1.2.3.
 *
 ****************************************************************************
 *
 */

/*include start*/
#define APP_NAME  "fdbaudit"
#define APP_DESC  "dbaudit example using libpcap"
#define APP_COPYRIGHT         "Copyright (c) 2011 dbaudit"
#define APP_DISCLAIMER         "THERE IS ABSOLUTELY NO WARRANTY FOR THIS PROGRAM."

#include <pcap.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

//#define OFFLINE //when read offline file
#define MAX_S 1024//copy to file
/*include end*/

/*protocol define start*/
/* default snap length (maximum bytes per packet to capture) */
#define SNAP_LEN 1518

/* ethernet headers are always exactly 14 bytes [1] */
#define SIZE_ETHERNET 14

/* Ethernet addresses are 6 bytes */
#define ETHER_ADDR_LEN 6

/* Ethernet header */
struct db_ethernet {
        u_char  ether_dhost[ETHER_ADDR_LEN];    /* destination host address */
        u_char  ether_shost[ETHER_ADDR_LEN];    /* source host address */
        u_short ether_type;                     /* IP? ARP? RARP? etc */
};

/* IP header */
struct db_ip {
        u_char  ip_vhl;                 /* version << 4 | header length >> 2 */
        u_char  ip_tos;                 /* type of service */
        u_short ip_len;                 /* total length */
        u_short ip_id;                  /* identification */
        u_short ip_off;                 /* fragment offset field */
        #define IP_RF 0x8000            /* reserved fragment flag */
        #define IP_DF 0x4000            /* dont fragment flag */
        #define IP_MF 0x2000            /* more fragments flag */
        #define IP_OFFMASK 0x1fff       /* mask for fragmenting bits */
        u_char  ip_ttl;                 /* time to live */
        u_char  ip_p;                   /* protocol */
        u_short ip_sum;                 /* checksum */
        struct  in_addr ip_src,ip_dst;  /* source and dest address */
};
#define IP_HL(ip)               (((ip)->ip_vhl) & 0x0f)
#define IP_V(ip)                (((ip)->ip_vhl) >> 4)

/* TCP header */
typedef u_int tcp_seq;

struct db_tcp {
        u_short th_sport;               /* source port */
        u_short th_dport;               /* destination port */
        tcp_seq th_seq;                 /* sequence number */
        tcp_seq th_ack;                 /* acknowledgement number */
        u_char  th_offx2;               /* data offset, rsvd */
#define TH_OFF(th)      (((th)->th_offx2 & 0xf0) >> 4)
        u_char  th_flags;
        #define TH_FIN  0x01
        #define TH_SYN  0x02
        #define TH_RST  0x04
        #define TH_PUSH 0x08
        #define TH_ACK  0x10
        #define TH_URG  0x20
        #define TH_ECE  0x40
        #define TH_CWR  0x80
        #define TH_FLAGS        (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
        u_short th_win;                 /* window */
        u_short th_sum;                 /* checksum */
        u_short th_urp;                 /* urgent pointer */
};

/* UDP header */
struct db_udp//udp protocol
{
 u_int16_t udp_source_port;
 u_int16_t udp_destination_port;
 u_int16_t udp_length;
 u_int16_t udp_checksum;
};

/* mysql header */
struct db_mysql
{
 u_int8_t mysql_header_length;
 u_int16_t unknow1;
 u_int8_t packet_num;
 u_int8_t qry;
 u_int16_t q1;
 u_int16_t q2;
 u_int16_t q3;
};


/*Oracle header-tns protocol*/

struct db_tns
{
 u_short length;//package  length
 u_short packet_checksum;//
 u_char type;//tns type
 u_char flag;//status
 u_short header_checksum;
};

struct db_tns_connect//0x01
{
 u_short ns_vr;
 u_short ns_compatible_ver;
 u_short ser_opt;
// u_char ser_opt2;
 u_short SDU_size;
 u_short TDU_size;
 u_short NT_protocol_ch;
// u_char NT_protocol_ch2;
 u_short max_packets;
 u_short hardware;
 u_short data_length;
 u_short offset;
 u_int32_t max_data;
 u_char flag0;
 u_char flag1;
/*
if not jdbc,use offet to override these;
*/
 u_int32_t item;
 u_int32_t item2;
 u_char id[8];
 u_char unkonwn[8];
// u_char *buff; //no need
};

struct db_tns_accept//0x02
{
 u_short ns_vr;
 u_short ser_opt;
// u_char ser_opt2;//no need
 u_short SDU_size;
 u_short TDU_size;
 u_short hardware;
 u_short data_length;
 u_short offset;
 u_char flag0;
 u_char flag1;
};

struct db_tns_reject//0x04
{
 u_char usr_refuse_reason;
 u_char sys_refuse_reason;
 u_char data_length;
};

struct db_tns_redirect//0x05
{
 u_short data_length;
 u_char data;//
};

struct db_tns_marker//0x0c
{
 //u_char data_length[3];
 u_char type;
 u_char data_byte0;
 u_char data_byte1;
};

struct db_tns_data
{
 u_short data_flag;//Data Flag
 
};
/*sqlserver header-tds protocol*/
/*DB2 header-db2 protocol*/
/*sybase header-npgsql protocol*/
/*Postgresql header-tds protocol*/

/*protocol define end*/

/*function define start*/
void
got_ethernet_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet);

void
got_ip_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet);

void
got_tcp_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_ip);

void
got_udp_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_ip);

void
got_mysql_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_tcp);

void
got_tns_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_tcp);

void
got_data_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_header);

void
print_payload(const u_char *payload, int len);

void
print_hex_ascii_line(const u_char *payload, int len, int offset);

void
print_app_banner(void);

void
print_app_usage(void);

void
put_in_file(const u_char *buff,int len);
/*function define end*/

/*function implement start*/

/*
 * app name/banner
 */
void
print_app_banner(void)
{

 printf("%s - %s\n", APP_NAME, APP_DESC);
 printf("%s\n", APP_COPYRIGHT);
 printf("%s\n", APP_DISCLAIMER);
 printf("\n");

return;
}

/*
 * print help text
 */
void
print_app_usage(void)
{

 printf("Usage: %s [interface]\n", APP_NAME);
 printf("\n");
 printf("Options:\n");
 printf("    interface    Listen on <interface> for packets.\n");
 printf("\n");

return;
}

/*
 * print data in rows of 16 bytes: offset   hex   ascii
 *
 * 00000   47 45 54 20 2f 20 48 54  54 50 2f 31 2e 31 0d 0a   GET / HTTP/1.1..
 */
void
print_hex_ascii_line(const u_char *payload, int len, int offset)
{

 int i;
 int gap;
 const u_char *ch;

 /* offset */
 printf("%05d   ", offset);
 
 /* hex */
 ch = payload;
 for(i = 0; i < len; i++) {
  printf("%02x ", *ch);
  ch++;
  /* print extra space after 8th byte for visual aid */
  if (i == 7)
   printf(" ");
 }
 /* print space to handle line less than 8 bytes */
 if (len < 8)
  printf(" ");
 
 /* fill hex gap with spaces if not full line */
 if (len < 16) {
  gap = 16 - len;
  for (i = 0; i < gap; i++) {
   printf("   ");
  }
 }
 printf("   ");
 
 /* ascii (if printable) */
 ch = payload;
 for(i = 0; i < len; i++) {
  if (isprint(*ch))
   printf("%c", *ch);
  else
   printf(".");
  ch++;
 }

 printf("\n");

return;
}

/*
 * print packet payload data (avoid printing binary data)
 */
void
print_payload(const u_char *payload, int len)
{

 int len_rem = len;
 int line_width = 16;   /* number of bytes per line */
 int line_len;
 int offset = 0;     /* zero-based offset counter */
 const u_char *ch = payload;

 if (len <= 0)
  return;

 /* data fits on one line */
 if (len <= line_width) {
  print_hex_ascii_line(ch, len, offset);
  return;
 }

 /* data spans multiple lines */
 for ( ;; ) {
  /* compute current line length */
  line_len = line_width % len_rem;
  /* print line */
  print_hex_ascii_line(ch, line_len, offset);
  /* compute total remaining */
  len_rem = len_rem - line_len;
  /* shift pointer to remaining bytes to print */
  ch = ch + line_len;
  /* add offset */
  offset = offset + line_width;
  /* check if we have line width chars or less */
  if (len_rem <= line_width) {
   /* print last line and get out */
   print_hex_ascii_line(ch, len_rem, offset);
   break;
  }
 }

return;
}
/*
putting buffer into buffer.txt
*/
void put_in_file(const u_char *buff,int len)
{
 u_char tmp[MAX_S];
 FILE *buffer;
 memcpy(tmp,buff,len);
 buffer=fopen("buffer.txt","ab");//append binary
 if(buffer==NULL)
  printf("FILE OPEN/CREATE FAIL\n");
 else{
 fwrite(tmp,sizeof(u_char),len,buffer);
 fwrite("\n",sizeof(char),1,buffer);
 fclose(buffer);
 }
 
}
/*
 * dissect/print data packet
 */
void
got_data_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_header)
{
 const u_char *payload;                    /* Packet payload */
 int size_payload;
 
 /* define/compute  payload (segment) offset */
 payload = (u_char *)(packet + size_header);
 
 /* compute tcp payload (segment) size */
 const struct db_ip *ip;
 ip = (struct db_ip*)(packet + SIZE_ETHERNET);
 size_payload = ntohs(ip->ip_len) - (size_header-SIZE_ETHERNET);//data len=total len-size_ip-size_tcp
 
 /*
  * Print payload data; it might be binary, so don't just
  * treat it as a string.
  */
 if (size_payload > 0) {
  printf("   Payload (%d bytes):\n", size_payload);
  print_payload(payload, size_payload);
 }
return;
}


/*
 * dissect/print mysql packet
 */
void
got_mysql_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_tcp)
{
 struct  db_mysql *mysql;
 int  size_mysql;
 u_short pa_num;
 u_short qry;
 u_short  hlen;
 mysql=(struct db_mysql*)(packet+size_tcp);
 hlen=ntohs(mysql->mysql_header_length);
 pa_num=ntohs(mysql->packet_num);
 qry=ntohs(mysql->qry);
 printf("********************MYSQL Protocol*************************\n");
 printf("Unknown:%02x\n",mysql->unknow1);
 printf("Header length:%d----------%02x\n",hlen,mysql->mysql_header_length);
 printf("Packet Number:%d---------%02x\n",pa_num,mysql->packet_num);
 printf("Query :%d----------------%02x\n*****************************\n",qry,mysql->qry);
 printf("Unknown:%02x\n",mysql->q1);
 printf("Unknown:%02x\n",mysql->q2);
 printf("Unknown:%02x\n",mysql->q3);
 
 /*handle  the  mysql  data */
 size_mysql=size_tcp+sizeof(mysql);
 got_data_package(args,header,packet,size_mysql);
 
return;
}
/*
 * dissect/print tns packet
 */
void
got_tns_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_tcp)
{
 int i;
 struct db_tns *tns;
 u_char *buff;
 tns=(struct db_tns*)(packet+size_tcp);
 printf("********************ORACLE TNS Protocol*************************\n"); printf("size_tcp:%d\n",size_tcp);
 if(size_tcp==header->len)
  printf("The TNS Packet is empty\n");
 else{
 printf("Length:%d\n",ntohs(tns->length));
 printf("Packet checksum:0x%02x\n",tns->packet_checksum);
 printf("Type:%02x\n",tns->type);
 printf("Flag:%02x\n",tns->flag);
 printf("Header Checksum:0x%02x\n",tns->header_checksum);
 
 int  size_data=size_tcp+sizeof(struct db_tns);
 switch (tns->type)
 {
  case 0x01: //analyzing connect packet
  {
   printf("connect  package\n");
   struct db_tns_connect* con;
   con=(struct db_tns_connect*)(packet+size_data);
  
   printf("version::%d\n",ntohs(con->ns_vr));
   printf("version(compatible):%d\n",ntohs(con->ns_compatible_ver));
   printf("Service Options:%02x\n",ntohs(con->ser_opt));
//   printf("Service Options2:%04x\n",con->ser_opt2);
   printf("Session Data Unit Size:%d\n",ntohs(con->SDU_size));
   printf("Max Trans Data Unit:%d\n",ntohs(con->TDU_size));
   printf("NT Protocol characteristics1:%04x\n",ntohs(con->NT_protocol_ch));
//   printf("NT Protocol characteristics2:%02x\n",con->NT_protocol_ch2);
   printf("Max packets:%d\n",ntohs(con->max_packets));
   printf("Hardware:%02x\n",con->hardware);
   printf("lentgh of Connect Data:%d\n",ntohs(con->data_length));
   printf("Offset of Connect Data:%d\n",ntohs(con->offset));
   printf("Max Receivable Connect Data:%d\n",ntohl(con->max_data));
   printf("Flags 0:%02x\n",con->flag0);
   printf("Flags 1:%02x\n",con->flag1);

   printf("Trace Cross Facility Item 1:%08x\n",con->item);
   printf("Trace Cross Facility Item 2:%08x\n",con->item2);
   printf("Trace Unique Connect ID:%16x\n",ntohs(con->id));
//   print_payload(con->buff,strlen(con->buff));
   buff=(u_char *)(packet+size_data+sizeof(struct db_tns_connect)-2);//-2 =offset?
   printf("BUFFER LEN:%d\n",strlen(buff));
   put_in_file(buff,strlen(buff));
   break;
  }
  case 0x02://analyzing accept package
  {
   printf("accept package\n");
   struct db_tns_accept* con;
   con=(struct db_tns_accept*)(packet+size_data);  
   printf("Version:%d\n",ntohs(con->ns_vr));
   printf("Service Options:%02x\n",ntohs(con->ser_opt));
   printf("Session Data Unit Size:%d\n",ntohs(con->SDU_size));
   printf("Max Trans Data Unit:%d\n",ntohs(con->TDU_size));
   printf("Hardware:%02x\n",con->hardware);
   printf("Accept Data Length:%d\n",ntohs(con->data_length));
   printf("Offset to Accept Data:%d\n",ntohs(con->offset));

   printf("Flags 0:%02x\n",con->flag0);
   printf("Flags 1:%02x\n",con->flag1);
   break;
  }
  case 0x03:
  {
   printf("ack package\n");
  

  
   break;
  }
  case 0x04:
  {
   printf("reject package\n");
   struct db_tns_reject* con;
   con=(struct db_tns_reject*)(packet+size_data);
   printf("User Refuse Reason 0:%02x\n",con->usr_refuse_reason);
   printf("System Refuse Reason 0:%02x\n",con->sys_refuse_reason);
   printf("Data Length:%d\n",ntohs(con->data_length));
   break;
  }
  case 0x05:
  {
   printf("redirect package\n");
   struct db_tns_redirect* con;
   con=(struct db_tns_redirect*)(packet+size_data);
   printf("Data Length:%d\n",ntohs(con->data_length));
   printf("Data:%02x\n",con->data);//?
   break;
  }
  case 0x06:
  { printf("data package\n");
   //need to analyse data packages?
   break;
  }
  case 0x09: printf("abort package\n");break;
  case 0x0b:printf("resend package,no content in this type of packet\n");break;
  case 0x0c:
  {
   printf("marker package\n");
   struct db_tns_marker* con;
   con=(struct db_tns_marker*)(packet+size_data);
   printf("Marker Type:%02x\n",con->type);
   printf("Marker Data Type:%02x\n",con->data_byte0);
   printf("Marker Data Type:%02x\n",con->data_byte1);  
   break;
  }
  case 0x0d:printf("attention package\n");break;
                case 0x0e:printf("control package\n");break;
  default:break;
 }}
return;
}
/*
 * dissect/print udp packet
 */
void
got_udp_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_ip)
{
 struct db_udp *udp;
 int  size_udp;
 u_short sport;
 u_short dport;
 u_short length;
 udp=(struct db_udp*)(packet+size_ip);
 sport=ntohs(udp->udp_source_port);
 dport=ntohs(udp->udp_destination_port);
 length=ntohs(udp->udp_length);
 printf("-------UDP Protocol (Transport Layer)---------\n");
 printf("Source Port:%d\n",sport);
 printf("Destination Port:%d\n",dport);
 printf("Length:%d\n",length);
 printf("Checksum:%d\n",ntohs(udp->udp_checksum));
 size_udp=length+size_ip;
 
 if(sport==3306  ||  dport==3306)
 {
  printf("mysql  protocol\n");
  got_mysql_package(args,header,packet,size_udp);
 }
 else if(sport==1521  ||  dport==1521)
 {
  printf("Oracle tns  protocol\n");
  got_tns_package(args,header,packet,size_udp);
 }
 else if(sport==1433  ||  dport==1433)
  printf("SQLSERVER tds  protocol\n");

 else got_data_package(args,header,packet,size_udp);

return;
}

/*
 * dissect/print tcp packet
 */
void
got_tcp_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet,int size_ip)
{
 const struct db_tcp *tcp;            /* The TCP header */
 int size_tcp;
 u_char flags;
 u_short windows;
 u_short urgent_pointer;
 u_int sequence;
 u_int acknowledgement;
 u_int16_t checksum;
 u_short sport;
 u_short dport;
 
 /* define/compute tcp header offset */
 tcp = (struct db_tcp*)(packet + size_ip);
 size_tcp = TH_OFF(tcp)*4;

 if (size_tcp < 20) {
  printf(" * Invalid TCP header length: %u bytes\n", size_tcp);
  return;
 }
 sequence=ntohl(tcp->th_seq);
 acknowledgement=ntohl(tcp->th_ack);
 windows=ntohs(tcp->th_win);
 urgent_pointer=ntohs(tcp->th_urp);
 flags=tcp->th_flags;
 checksum=ntohs(tcp->th_sum);
 sport=ntohs(tcp->th_sport);
 dport=ntohs(tcp->th_dport);
 printf("-------TCP Protocol (Transport Layer)---------\n");
 printf("   Src port: %d\n", sport);
 printf("   Dst port: %d\n", dport);
 printf("Sequence Number:%u\n Acknowledgement Number:%u\n Header Length:%d\n Reserved:%d\n",sequence,acknowledgement,size_tcp,tcp->th_offx2);
 printf("Flags:");
 if(flags & 0x08) printf("PSH");
 if(flags & 0x10) printf("ACK");
 if(flags & 0x02) printf("SYN");
 if(flags & 0x20) printf("URG");
 if(flags & 0x01) printf("FIN");
 if(flags & 0x04) printf("RST");
 printf("\n");
 printf("Window Size:%d\n",windows);
 printf("Checksum:%d\n",checksum);
 printf("Urgent Pointer:%d\n",urgent_pointer);
 
 size_tcp=size_tcp+size_ip;
 if(sport==3306  ||  dport==3306)
 {
  printf("mysql  protocol\n");
  got_mysql_package(args,header,packet,size_tcp);
 }
 else if(sport==1521  ||  dport==1521)
 {
  printf("Oracle tns  protocol\n");
  got_tns_package(args,header,packet,size_tcp);
 }
 else if(sport==1433  ||  dport==1433)
  printf("SQLSERVER tds  protocol\n");
 else got_data_package(args,header,packet,size_tcp);
 
return;
}
/*
 * dissect/print ip packet
 */
void
got_ip_package(u_char *args,const struct pcap_pkthdr *header,const u_char *packet)
{
        const struct db_ip *ip;              /* The IP header */
        int size_ip;
        u_int offset;
        u_char tos;
 u_int16_t checksum;
      
        /* define/compute ip header offset */
 ip = (struct db_ip*)(packet + SIZE_ETHERNET);
 size_ip = IP_HL(ip)*4;
 if (size_ip < 20) {
  printf("*Invalid IP header length: %u bytes\n", size_ip);
  return;
 }
        checksum=ntohs(ip->ip_sum);
 tos=ip->ip_tos;
 offset=ntohs(ip->ip_off);

 /* print source and destination IP addresses */
        printf("-------IP Protocol (Network Layer)---------\n");
        printf("IP Version:%d\n",IP_V(ip));
 printf("Header Length:%d\n",size_ip);
 printf("TOS:%d\n",tos);
 printf("Total length:%d\n",ntohs(ip->ip_len));
 printf("Identification:%d\n",ntohs(ip->ip_id));
 printf("Offset:%d\n",(offset & 0x1fff)*8);
 printf("TTL:%d\n",ip->ip_ttl);
 printf("Header checksum:%d\n",checksum);
 printf(" From: %s", inet_ntoa(ip->ip_src));
 printf("  To: %s\n", inet_ntoa(ip->ip_dst));
 
 /* determine protocol */
 size_ip=size_ip+SIZE_ETHERNET;
 switch(ip->ip_p) {
  case IPPROTO_TCP:
   got_tcp_package(args,header,packet,size_ip);
   break;
  case IPPROTO_UDP:
   got_udp_package(args,header,packet,size_ip);
   break;
  default:
   printf("   Protocol: unknown\n");
   break;
 }
return;
}

/*
 * dissect/print ethernet packet
 */
void
got_ethernet_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet)
{
 static int count = 1;                   /* packet counter */
 
 /* declare pointers to packet headers */
 const struct db_ethernet *ethernet;  /* The ethernet header [1] */
        u_short ethernet_type;
        u_char *mac_string;

 printf("================The %d package is captured.======================\n",count);
 count++;

        printf("-------Ethernet Protocol (Link Layer)---------\n");
 /* get ethernet header */   
 ethernet = (struct db_ethernet*)(packet);
 printf("Mac Source Address is:\n");
 mac_string=(u_char*)ethernet->ether_shost;
 printf("%02x:%02x:%02x:%02x:%02x:%02x\n",*mac_string,*(mac_string+1),*(mac_string+2),*(mac_string+3),*(mac_string+4),*(mac_string+5));
 printf("Mac Destination Address is:\n");
 mac_string=(u_char*)ethernet->ether_dhost;
 printf("%02x:%02x:%02x:%02x:%02x:%02x\n",*mac_string,*(mac_string+1),*(mac_string+2),*(mac_string+3),*(mac_string+4),*(mac_string+5));
 ethernet_type=ntohs(ethernet ->ether_type);
        switch(ethernet_type)
 {
 case 0x0800: got_ip_package(args,header,packet);break;
 case 0x0806: printf("The network layer is ARP protocol\n");break;
 case 0x0835: printf("The network layer is RARP protocol\n");break;
 default:break;
 }
return;
}
/*function implement end*/

/*main function,entrance for system*/
int main(int argc, char **argv)
{

 char *dev = NULL;   /* capture device name */
 char errbuf[PCAP_ERRBUF_SIZE];  /* error buffer */
 pcap_t *handle;    /* packet capture handle */
 char filter_exp[] = "ip";
 //char filter_exp[] = "ip host 127.0.0.1";/*port 3306*//* filter expression [3] */
 struct bpf_program fp;   /* compiled filter program (expression) */
 bpf_u_int32 mask;   /* subnet mask */
 bpf_u_int32 net;   /* ip */
 int num_packets = -1;   /* number of packets to capture ,-1 is loop*/

 print_app_banner();

 /* check for capture device name on command-line */
 if (argc == 2) {
  dev = argv[1];
 }
 else if (argc > 2) {
  fprintf(stderr, "error: unrecognized command-line options\n\n");
  print_app_usage();
  exit(EXIT_FAILURE);
 }
 else {
  /* find a capture device if not specified on command-line */
  dev = pcap_lookupdev(errbuf);
  if (dev == NULL) {
   fprintf(stderr, "Couldn't find default device: %s\n",
       errbuf);
   exit(EXIT_FAILURE);
  }
 }
 
 /* get network number and mask associated with capture device */
 if (pcap_lookupnet(dev, &net, &mask, errbuf) == -1) {
  fprintf(stderr, "Couldn't get netmask for device %s: %s\n",
      dev, errbuf);
  net = 0;
  mask = 0;
 }

 /* print capture info */
 printf("Device: %s\n", dev);
 printf("Number of packets: %d\n", num_packets);
 printf("Filter expression: %s\n", filter_exp);

#ifdef OFFLINE
 handle=pcap_open_offline("tns.pcap",errbuf);//read  offline  file
#else
 /* open capture device */
 handle = pcap_open_live(dev, SNAP_LEN, 1, 1000, errbuf);
#endif
 if (handle == NULL) {
  fprintf(stderr, "Couldn't open device %s: %s\n", dev, errbuf);
  exit(EXIT_FAILURE);
 }

 /* make sure we're capturing on an Ethernet device [2] */
 if (pcap_datalink(handle) != DLT_EN10MB) {
  fprintf(stderr, "%s is not an Ethernet\n", dev);
  exit(EXIT_FAILURE);
 }

 /* compile the filter expression */
 if (pcap_compile(handle, &fp, filter_exp, 0, net) == -1) {
  fprintf(stderr, "Couldn't parse filter %s: %s\n",
      filter_exp, pcap_geterr(handle));
  exit(EXIT_FAILURE);
 }

 /* apply the compiled filter */
 if (pcap_setfilter(handle, &fp) == -1) {
  fprintf(stderr, "Couldn't install filter %s: %s\n",
      filter_exp, pcap_geterr(handle));
  exit(EXIT_FAILURE);
 }

 /* now we can set our callback function */
 pcap_loop(handle, num_packets, got_ethernet_packet, NULL);

 /* cleanup */
 pcap_freecode(&fp);
 pcap_close(handle);

 printf("\nCapture complete.\n");

return 0;
}

 

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