LinuxCraw_socket（原始套接字）

#include
#include
#include
#include if.h>
#include <string.h>
#include
#include
#include
#include
#include in.h>
typedef struct _iphdr //定义IP首部
{
unsigned char h_verlen; //4位首部长度&＃43;4位IP版本号
unsigned char tos; //8位服务类型TOS
unsigned short total_len; //16位总长度&＃xff08;字节&＃xff09;
unsigned short ident; //16位标识
unsigned short frag_and_flags; //3位标志位
unsigned char ttl; //8位生存时间 TTL
unsigned char proto; //8位协议 (TCP, UDP 或其他)
unsigned short checksum; //16位IP首部校验和
unsigned int sourceIP; //32位源IP地址
unsigned int destIP; //32位目的IP地址
}IP_HEADER;
typedef struct _udphdr //定义UDP首部
{
unsigned short uh_sport; //16位源端口
unsigned short uh_dport; //16位目的端口
unsigned int uh_len;//16位UDP包长度
unsigned int uh_sum;//16位校验和
}UDP_HEADER;
typedef struct _tcphdr //定义TCP首部
{
unsigned short th_sport; //16位源端口
unsigned short th_dport; //16位目的端口
unsigned int th_seq; //32位序列号
unsigned int th_ack; //32位确认号
unsigned char th_lenres;//4位首部长度/6位保留字
unsigned char th_flag; //6位标志位
unsigned short th_win; //16位窗口大小
unsigned short th_sum; //16位校验和
unsigned short th_urp; //16位紧急数据偏移量
}TCP_HEADER;
typedef struct _icmphdr {
unsigned char icmp_type;
unsigned char icmp_code; /* type sub code */
unsigned short icmp_cksum;
unsigned short icmp_id;
unsigned short icmp_seq;
/* This is not the std header, but we reserve space for time */
unsigned short icmp_timestamp;
}ICMP_HEADER;
void analyseIP(IP_HEADER *ip);
void analyseTCP(TCP_HEADER *tcp);
void analyseUDP(UDP_HEADER *udp);
void analyseICMP(ICMP_HEADER *icmp);
int main(void)
{
int sockfd;
IP_HEADER *ip;
char buf[10240];
ssize_t n;
/* capture ip datagram without ethernet header */
if ((sockfd &＃61; socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)))&＃61;&＃61; -1)
{
printf("socket error!\n");
return 1;
}
while (1)
{
n &＃61; recv(sockfd, buf, sizeof(buf), 0);
if (n &＃61;&＃61; -1)
{
printf("recv error!\n");
break;
}
else if (n&＃61;&＃61;0)
continue;
//接收数据不包括数据链路帧头
ip &＃61; ( IP_HEADER *)(buf);
analyseIP(ip);
size_t iplen &＃61; (ip->h_verlen&0x0f)*4;
TCP_HEADER *tcp &＃61; (TCP_HEADER *)(buf &＃43;iplen);
if (ip->proto &＃61;&＃61; IPPROTO_TCP)
{
TCP_HEADER *tcp &＃61; (TCP_HEADER *)(buf &＃43;iplen);
analyseTCP(tcp);
}
else if (ip->proto &＃61;&＃61; IPPROTO_UDP)
{
UDP_HEADER *udp &＃61; (UDP_HEADER *)(buf &＃43; iplen);
analyseUDP(udp);
}
else if (ip->proto &＃61;&＃61; IPPROTO_ICMP)
{
ICMP_HEADER *icmp &＃61; (ICMP_HEADER *)(buf &＃43; iplen);
analyseICMP(icmp);
}
else if (ip->proto &＃61;&＃61; IPPROTO_IGMP)
{
printf("IGMP----\n");
}
else
{
printf("other protocol!\n");
}
printf("\n\n");
}
close(sockfd);
return 0;
}
void analyseIP(IP_HEADER *ip)
{
unsigned char* p &＃61; (unsigned char*)&ip->sourceIP;
printf("Source IP\t: %u.%u.%u.%u\n",p[0],p[1],p[2],p[3]);
p &＃61; (unsigned char*)&ip->destIP;
printf("Destination IP\t: %u.%u.%u.%u\n",p[0],p[1],p[2],p[3]);
}
void analyseTCP(TCP_HEADER *tcp)
{
printf("TCP -----\n");
printf("Source port: %u\n", ntohs(tcp->th_sport));
printf("Dest port: %u\n", ntohs(tcp->th_dport));
}
void analyseUDP(UDP_HEADER *udp)
{
printf("UDP -----\n");
printf("Source port: %u\n", ntohs(udp->uh_sport));
printf("Dest port: %u\n", ntohs(udp->uh_dport));
}
void analyseICMP(ICMP_HEADER *icmp)
{
printf("ICMP -----\n");
printf("type: %u\n", icmp->icmp_type);
printf("sub code: %u\n", icmp->icmp_code);
}