libpcap报文解析: ipv4、ipv6（待优化）

 #include <string.h>
 #include <stdlib.h>
 #include <pcap.h>
 #include <netinet/in.h>
 #include "packet_header.h"

 #define MAXBYTE2CAPTURE 2048

 int isprint(char c)
 {
     return ;
 }

 void print_buf(u_char* pBuf, u_int32 len)
 {
     if (!pBuf)
     {
         return;
     }

     for(int i=; i<len; i++)
     {
         printf("%02x ",  (u_char*)pBuf[i]);

         if ((i% ==  && i!=) || i == len-)
         {
             printf("\r\n");
         }
     }
 }

 void parse_ethII(u_char* pData, u_int32 len)
 {
     if (!pData || len <)
     {
         return;
     }

     printf("eth II frame: \r\n");
     print_buf(pData, );

     /* parse src mac and dst mac */
     EthHeader_t* pEth = (EthHeader_t*)pData;
     printf("destination: %02x:%02x:%02x:%02x:%02x:%02x ",
         pEth->dest_hwaddr[],
         pEth->dest_hwaddr[],
         pEth->dest_hwaddr[],
         pEth->dest_hwaddr[],
         pEth->dest_hwaddr[],
         pEth->dest_hwaddr[]);

     printf("source : %02x:%02x:%02x:%02x:%02x:%02x",
         pEth->source_hwaddr[],
         pEth->source_hwaddr[],
         pEth->source_hwaddr[],
         pEth->source_hwaddr[],
         pEth->source_hwaddr[],
         pEth->source_hwaddr[]);

     /* parse frame type */
     printf("\r\nframe type: 0x%x\r\n", ntohs(pEth->frame_type));
 }

 void parse_ipheader(u_char* pData, u_int32 len)
 {
     if (!pData || len <)
     {
         return;
     }

     printf("ip header: \r\n");
     print_buf(pData, );

     /* parse ip header */
     IPHeader_t* pIpHeader = (IPHeader_t*)pData;
     printf("\tversion     : %02x\r\n"
            "\ttos         : %02x\r\n"
            "\ttotal length: %d(0x%02x)\r\n"
            "\tid          : %d(0x%02x)\r\n"
            "\tsegment flag: %d(0x%02x)\r\n"
            "\tttl         : %02x\r\n"
            "\tprotocol    : %02x\r\n"
            "\tchecksum    : %d(0x%02x)\r\n"
            "\tsrc ip      : %d.%d.%d.%d\r\n"
            "\tdst ip      : %d.%d.%d.%d\r\n",
         pIpHeader->Ver_HLen,
         pIpHeader->TOS,
         ntohs(pIpHeader->TotalLen), ntohs(pIpHeader->TotalLen),
         ntohs(pIpHeader->ID), ntohs(pIpHeader->ID),
         ntohs(pIpHeader->Flag_Segment), ntohs(pIpHeader->Flag_Segment),
         pIpHeader->TTL,
         pIpHeader->Protocol,
         ntohs(pIpHeader->Checksum), ntohs(pIpHeader->Checksum),
         pIpHeader->SrcIP[],pIpHeader->SrcIP[],pIpHeader->SrcIP[],pIpHeader->SrcIP[],
         pIpHeader->DstIP[],pIpHeader->DstIP[],pIpHeader->DstIP[],pIpHeader->DstIP[]);
 }

 void parse_ip6header(u_char* pData, u_int32 len)
 {
     if (!pData || len <)
     {
         return;
     }

     printf("ipv6 header: \r\n");
     print_buf(pData, );

     /* parse ipv6 header */
     IPv6Header_t* pIpv6Header = (IPv6Header_t*)pData;
     printf("\tversion           : %x\r\n"
            "\ttraffic class     : %x\r\n"
            "\tflow label        : %x\r\n"
            "\tpayload length    : %x\r\n"
            "\tnext header       : %x\r\n"
            "\thop limit         : %x\r\n"
            "\tsource            : %x\r\n"
            "\tdestination       : %x\r\n",
            pIpv6Header->ip6_ctlun.ip6_un2_vfc,
            pIpv6Header->ip6_ctlun.ip6_unl.ip6_unl_flow,
            pIpv6Header->ip6_ctlun.ip6_unl.ip6_unl_flow,
            pIpv6Header->ip6_ctlun.ip6_unl.ip6_unl_plen,
            pIpv6Header->ip6_ctlun.ip6_unl.ip6_unl_nxt,
            pIpv6Header->ip6_ctlun.ip6_unl.ip6_unl_hlim,
            pIpv6Header->ip6_src,
            pIpv6Header->ip6_dst);
 }

 void parse_packet(const u_char* packet, u_int32 len)
 {
     u_short ftype = ;

     if (!packet)
     {
         return ;
     }

     u_char* pMbuf = (u_char*)packet;
     parse_ethII(pMbuf, len);

     ftype = ntohs(((EthHeader_t*)pMbuf)->frame_type);
     switch(ftype)
     {
         case 0x0800:  /* ipv4 */
             pMbuf = (u_char*)packet + ;
             parse_ipheader(pMbuf, len-);
             break;
         case 0x86dd: /* ipv6 */
             pMbuf = (u_char*)packet + ;
             parse_ip6header(pMbuf, len-);
             break;
         default:
             printf("frame type : 0x%x\r\n", ftype);
             break;
     }

     printf("\r\n");
 }

 void processPacket(u_char *arg, const struct pcap_pkthdr *pkthdr, const u_char *packet)
 {
     int i = , *counter = (int *)arg;

     printf("--------------------------------------------\r\n");
     printf("Packet Count: %d\n", ++(*counter));
     printf("Received Packet Size: %d\n", pkthdr->len);
     printf("Payload:\n");

 #if 1
     for (i = ; i < pkthdr->len; i++)
     {
         if (isprint(packet[i]))
         {
             printf("%02d ", packet[i]);
         }
         else
         {
             printf("%02x ", packet[i]);
         }

         if ((i %  ==  && i != ) || i == pkthdr->len-)
         {
             printf("\n");
         }

     }
 #endif

     parse_packet(packet, pkthdr->len);

     return;
 }

 int main()
 {

     int i = , count = ;
     pcap_t *descr = NULL;
     char errbuf[PCAP_ERRBUF_SIZE], *device = NULL;
     memset(errbuf, , PCAP_ERRBUF_SIZE);

     /* Get the name of the first device suitable for capture */
     device = pcap_lookupdev(errbuf);
     if (!device)
     {
         printf("Open device failed.");
         return -;
     }

     printf("Opening device %s\n", device);

     /* Open device in promiscuous mode */
     descr = pcap_open_live(device, MAXBYTE2CAPTURE, , , errbuf);

     /* Loop forever & call processPacket() for every received packet */
     pcap_loop(descr, -, processPacket, (u_char *)&count);

     return ;
 }

#ifndef PACKET_HEADER_H
#define PACKET_HEADER_H

#ifndef u_char
#define u_char unsigned char
#endif

#ifndef u_int8
#define u_int8 unsigned char
#endif

#ifndef u_int16
#define u_int16 unsigned short
#endif

#ifndef u_int32
#define u_int32 unsigned int
#endif

#ifndef u_int64
#define u_int64 unsigned long long
#endif

#ifndef u_short
#define u_short unsigned short
#endif

/* 以太帧头 */
typedef struct tagEthHeader_t
{
    //Pcap捕获的数据帧头
    u_int8 dest_hwaddr[];   //目的MAC地址
    u_int8 source_hwaddr[]; //源MAC地址
    u_short frame_type;      //帧类型
}EthHeader_t;

//IP数据报头
typedef struct tagIPHeader_t
{
    //IP数据报头
    u_int8  Ver_HLen; //版本+报头长度
    u_int8  TOS;      //服务类型
    u_int16 TotalLen;//总长度
    u_int16 ID;      //标识
    u_int16 Flag_Segment; //标志+片偏移
    u_int8  TTL;      //生存周期
    u_int8  Protocol; //协议类型
    u_int16 Checksum;//头部校验和
    u_int8 SrcIP[];   //源IP地址
    u_int8 DstIP[];   //目的IP地址
} IPHeader_t;

//IPv6基本首部
#if 0
typedef struct tagIPv6Header_t
{
    u_char    version:;      // 4-bit版本号
    u_char  traffic_class:;  // 8-bit流量等级
    u_int32 label:;       // 20-bit流标签
    u_short    payload_len;    // 16-bit 载荷长度
    u_char    next_header;    // 8-bit 下一首部
    u_char    hop_limit;        // 8-bit 跳数限制
    struct
    {
        u_int64 prefix_subnetid;
        u_char interface_id[];
    } src_ip;                // 128-bit 源地址
    struct
    {
        u_int64 prefix_subnetid;
        u_char interface_id[];
    } dst_ip;                // 128-bit 目的地址

} IPv6Header_t;

typedef struct in6_addr {
  union {
    u_char  Byte[];
    u_short Word[];
  } u;
} IN6_ADDR, *PIN6_ADDR, FAR *LPIN6_ADDR;

#endif

typedef struct tagIPv6Header_t
{
    union
    {
        struct ip6_hdrctl
        {
            u_int32_t ip6_unl_flow;/* 4位的版本，8位的传输与分类，20位的流标识符 */
            u_int16_t ip6_unl_plen;/* 报头长度 */
            u_int8_t ip6_unl_nxt;  /* 下一个报头 */
            u_int8_t ip6_unl_hlim; /* 跨度限制 */
        }ip6_unl ;

        u_int8_t ip6_un2_vfc;/* 4位的版本号，跨度为4位的传输分类 */
    }ip6_ctlun ;

#define ip6_vfc              ip6_ctlun.ip6_un2_vfc
#define ip6_flow             ip6_ctlun.ip6_unl.ip6_unl_flow
#define ip6_plen             ip6_ctlun.ip6_unl.ip6_unl_plen
#define ip6_nxt              ip6_ctlun.ip6_unl.ip6_unl_nxt
#define ip6_hlim             ip6_ctlun.ip6_unl.ip6_unl_hlim
#define ip6_hops             ip6_ctlun.ip6_unl.ip6_unl_hops

    struct in6_addr ip6_src;/* 发送端地址 */
    struct in6_addr ip6_dst;/* 接收端地址 */
}IPv6Header_t;

//TCP数据报头
typedef struct tagTCPHeader_t
{
    //TCP数据报头
    u_int16 SrcPort; //源端口
    u_int16 DstPort; //目的端口
    u_int32 SeqNO;   //序号
    u_int32 AckNO;   //确认号
} TCPHeader_t;

#endif