计算机网络课程设计——机械工业出版社第7章：解析IP数据包课程设计目的：本课程设计的目的就是设计一个解析IP数据包的程序，并根据这个程序，说明IP 数据包的结构及IP协议的相关问题，从而对IP层的工作原理有更好的理解和认识。
完整程序代码：#include<stdio.h>#include<winsock2.h>#include<ws2tcpip.h>#pragma comment(lib,"ws2_32.lib")typedef struct _IP_HEADER{union{BYTE Version;BYTE HdrLen;};BYTE ServiceType;WORD TotalLen;WORD ID;union{WORD Flags;WORD FragOff;};BYTE TimeToLive;BYTE Protocol;WORD HdrChksum;DWORD SrcAddr;DWORD DstAddr;BYTE Options;} IP_HEADER;#define IO_RCVALL _WSAIOW(IOC_VENDOR,1)#define BUFFER_SIZE 65535void getVersion(BYTE b,BYTE &version){version=b>>4;}void getIHL(BYTE b,BYTE &length){length=(b&0x0f)*4;}char* parseServiceType_getProcedence(BYTE b) {switch(b>>5){case 7:return "Network Control";break;case 6:return "internet work Control";break;case 5:return "CRITIC/ECP";break;case 4:return "Flash Override";break;case 3:return "Flash";break;case 2:return "Immediate";break;case 1:return "Priority";break;case 0:return "Routine";break;default:return "Unknown";}}char* parseServiceType_getTOS(BYTE b) {b=(b>>1)&0x0f;switch(b){case 0:return "Normal Service";break;case 1:return "Minimize monetary cost";break;case 2:return "Maximize reliability";break;case 4:return "Maximize throughput";break;case 8:return "Minimize delay";break;case 15:return "Maximize security";break;default:return "Unknown";}}void getFlags(WORD w,BYTE &DF,BYTE &MF) {DF=(w>>14)&0x01;MF=(w>>13)&0x01;}void getFragOff(WORD w,WORD &fragOff) {fragOff=w&0x1fff;}char* getProtocol(BYTE Protocol){switch (Protocol){case 1:return "ICMP";case 2:return "IGMP";case 4:return "IP in IP";case 6:return "TCP";case 8:return "EGP";case 17:return "UDP";case 41:return "IPv6";case 46:return "RSVP";case 89:return "OSPF";default:return "UNKNOWN";}}void ipparse(FILE* file,char* buffer){IP_HEADER ip=*(IP_HEADER*)buffer;fseek(file,0,SEEK_END);fprintf(file,"----------------------------------\n");BYTE version;getVersion(ip.Version,version);fprintf(file,"Version:%d\n",version);BYTE headerLen;getIHL(ip.HdrLen,headerLen);fprintf(file,"HdrLen:%d(Bytes)\n",headerLen);fprintf(file,"ServiceType: %s,%s\n",parseServiceType_getProcedence(ip.ServiceType),parseServiceType_getTOS(ip.ServiceType));fprintf(file,"TotalLen: %d(Bytes)\n",ip.TotalLen);fprintf(file,"ID: %d\n",ip.ID);BYTE DF,MF;getFlags(ip.Flags,DF,MF);fprintf(file,"Flags:DF=%d,MF=%d\n",DF,MF);WORD fragOff;getFragOff(ip.FragOff,fragOff);fprintf(file,"FragOff: %d\n",fragOff);fprintf(file,"FragOff: %d\n",fragOff);fprintf(file,"TimeToLive: %d(Hops)\n",ip.TimeToLive);fprintf(file,"Protocol: %s\n",getProtocol(ip.Protocol));fprintf(file,"HdrChksum: 0x%0x\n",ip.HdrChksum);fprintf(file,"SrcAddr: %s\n",inet_ntoa(*(in_addr*)&ip.SrcAddr));fprintf(file,"DstAddr: %s\n",inet_ntoa(*(in_addr*)&ip.DstAddr)); }void main(int argc,char*argv[]){if(argc!=2){printf("Please input command: ParseArp output_file");return;}FILE* file;if((file=fopen(argv[1],"wb+"))==NULL){printf("Fail to open file %s",argv[1]);return;}WSADATA wsData;if(WSAStartup(MAKEWORD(2,2),&wsData)!=0){printf("WSAStartup failed!");return;}SOCKET sock;if((sock=socket(AF_INET,SOCK_RAW,IPPROTO_IP))==INVALID_SOCK ET){printf("Creat socket failed");return;}BOOL flag=true;if(setsockopt(sock,IPPROTO_IP,IP_HDRINCL,(char*)&flag,sizeof(flag)) ==SOCKET_ERROR){printf("Setsockopt failed!");return;}char hostName[128];if(gethostname(hostName,100)==SOCKET_ERROR){printf("Gethostname failed!");return;}hostent* pHostIP;if((pHostIP=gethostbyname(hostName))==NULL){printf("Gethostbyname failed!");return;}sockaddr_in addr_in;addr_in.sin_addr=*(in_addr*)pHostIP->h_addr_list[0];addr_in.sin_family=AF_INET;addr_in.sin_port=htons(6000);if(bind(sock,(PSOCKADDR)&addr_in,sizeof(addr_in))==SOCKET_ERRO R){printf("Bind failed!");return;}DWORD dwValue=1;DWORD dwBufferLen[10];DWORD dwBufferInLen=1;DWORD dwBytesReturned=0;if(WSAIoctl(sock,IO_RCVALL,&dwBufferInLen,sizeof(dwBufferInLen),& dwBufferLen,sizeof(dwBufferLen),&dwBytesReturned,NULL,NULL)==SOCKET_ ERROR){printf("Ioctlsocket failed!");return;}char buffer[BUFFER_SIZE];printf("Listening on local host...\n");while(true){int size=recv(sock,buffer,BUFFER_SIZE,0);if(size>0){ipparse(stdout,buffer);ipparse(file,buffer);}}fclose(file);return;}结果截图。
