计算机网络的一个作业：实现ping+ip 不要求其它参数
用到的知识：ip报头结构，icmp报头结构，获取主机ip方法，winsock的简单操作
实现的结果：一般的ip能够ping通，如www.baidu.com, www.sina.com.cn
存在的问题：本机（127.0.0.1）ping不通
1 /*
2 *filename:ping.c
3 *author:ChrisZZ
4 */
5 #pragma comment(lib, "ws2_32.lib")
6 #include <stdio.h>
7 #include <winsock2.h>
8 #include <ws2tcpip.h>
9 #include <process.h>
10
11
12 struct IPHeader{//IPv4头部结构
13 unsigned char ver_hlen;//头部长度，用4位表示，range[5,15]
14 // unsigned int ver:4;//version
15 unsigned char tos;//type of service
16 unsigned short total_len;
17 unsigned short id;
18 unsigned short frags_and_flags;
19 unsigned char ttl;//time to live
20 unsigned char proto;//protocal
21 unsigned short chksum;//checksum
22 unsigned int srcIp;//source IP
23 unsigned int dstIp;//destination IP
24 };
25
26 struct ICMPHeader{//ICMP头部结构
27 unsigned char type;
28 unsigned char code;
29 unsigned short chksum;
30 unsigned short id;
31 unsigned short seq;//sequence
32 unsigned int timestamp;
33 };
34
35 #define ICMP_ECHO 8
36 #define ICMP_ECHO_REPLY 0
37 #define PACKAGE_SIZE sizeof(IPHeader)+sizeof(ICMPHeader)
38 void usage();
39 unsigned short CheckSum(unsigned short*, int);
40 void HandleError(char *);
41
42 //用法说明函数
43 void usage(){
44 printf("用法：ping 目标主机\n\n");
45 system("pause");
46 }
47
48 //错误处理函数
49 void HandleError(char *str){
50 int errCode=WSAGetLastError();
51
52 char info[65]={0};
53 _snprintf(info, 64, "%s: %d\n", str, errCode);
54 printf(info);
55 }
56
57 unsigned short checksum(unsigned short* buff, int size){
58 unsigned int chksum=0;
59 while(size>1){
60 chksum+=*buff++;
61 size-=sizeof(unsigned short);
62 }
63 if(size){
64 chksum+=*(unsigned char*)(buff);
65 }
66 chksum=(chksum>>16)+(chksum &0xffff);
67 chksum+=(chksum>>16);
68 return (unsigned short)(~chksum);
69 }
70
71 void FillPackage(char *pData, unsigned int dstIP, unsigned short id){
72 memset(pData, 0, PACKAGE_SIZE);
73
74 IPHeader *pIPHeader=(IPHeader*)pData;
75
76 int nVersion=4;
77 int nHeadSize=sizeof(IPHeader)/4;
78
79 //获得本机IP
80 struct sockaddr_in SrcAddr;
81 struct hostent * hpsrc;
82 char localhost[32];
83 gethostname(localhost, sizeof(localhost));
84 hpsrc=gethostbyname(localhost);
85 memset(&SrcAddr, 0, sizeof(SrcAddr));
86 memcpy(&(SrcAddr.sin_addr), hpsrc->h_addr, hpsrc->h_length);
87 SrcAddr.sin_port=htons(0);
88 SrcAddr.sin_family=AF_INET;
89
90
91 unsigned int srcIP=SrcAddr.sin_addr.s_addr;//本机IP
92 unsigned int destIp=dstIP;
93 pIPHeader->ver_hlen=(nVersion<<4)|nHeadSize;
94 pIPHeader->tos=0;
95 pIPHeader->total_len=htons(PACKAGE_SIZE);
96 pIPHeader->id=htons(1234);//????
97 pIPHeader->frags_and_flags=0;
98 pIPHeader->ttl=255;//??
99 pIPHeader->proto=IPPROTO_ICMP;
100 pIPHeader->chksum=0;
101 pIPHeader->srcIp=srcIP;
102 pIPHeader->dstIp=dstIP;
103
104 pIPHeader->chksum=checksum((unsigned short*)pData, sizeof(IPHeader));
105 ICMPHeader* pICMPHeader=(ICMPHeader*)(pData+sizeof(IPHeader));
106 pICMPHeader->type=ICMP_ECHO;
107 pICMPHeader->code=0;
108 pICMPHeader->chksum=0;
109 pICMPHeader->id=htons(id);
110 pICMPHeader->seq=htons(id);
111 pICMPHeader->chksum=checksum((unsigned short*)((char*)pData+sizeof(IPHeader)), sizeof(ICMPHeader));
112
113 }
114
115 int main(int argc, char* argv[]){
116
117 //初始化
118 WSADATA wsaData;
119 struct sockaddr_in DestAddr,from;
120 IPHeader *ip;
121 ICMPHeader *icmp;
122 ICMPHeader *SendIcmp;
123 int Timeout=1000;
124 char IcmpBuffer[PACKAGE_SIZE]="";
125 SOCKET IcmpSocket;
126 char RecvBuffer[1024];
127 sockaddr_in addr;
128 int Len = sizeof(addr);
129 int Result;
130 struct hostent * hpdst;
131 int pid=_getpid();
132 struct timeval tv;
133 fd_set readSet;
134 BOOL bBroadcast=false;
135
136 //确定参数个数
137 if(argc!=2){
138 printf("参数不正确\n");
139 usage();
140 return -1;
141 }
142
143
144 if ((Result = WSAStartup(MAKEWORD(2, 2), &wsaData)) != 0){
145 printf("WSAStartup failed with error %d\n", Result);
146 return 0;
147 }
148
149
150 //获取目的主机IP
151 hpdst=gethostbyname(argv[1]);
152 if(hpdst==NULL){
153 HandleError("gethostbyname");
154 WSACleanup();
155 return -1;
156 }
157
158 //创建ICMP封包并发送
159 //char buff[sizeof(ICMP_HDR)+32];
160 IcmpSocket=socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
161 if(IcmpSocket==INVALID_SOCKET){
162 HandleError("socket");
163 WSACleanup();
164 return -1;
165 }
166 BOOL on=TRUE;
167 Result=setsockopt(IcmpSocket,IPPROTO_IP,IP_HDRINCL, (char*)&on, sizeof(on));
168 if(Result==SOCKET_ERROR){
169 HandleError("socketopt");
170 WSACleanup();
171 return -1;
172 }
173 memset(&DestAddr, 0, sizeof(DestAddr));
174 memcpy(&(DestAddr.sin_addr), hpdst->h_addr, hpdst->h_length);
175 DestAddr.sin_port=htons(0);
176 /*reference:http://www.cnblogs.com/CBDoctor/archive/2012/10/28/2743109.html*/
177 DestAddr.sin_family=AF_INET;
178
179
180
181 int i;
182 for(i=0; i<3; i++){
183 if(i==0) printf("正在Ping %s 具有 %d 字节的数据:\n", inet_ntoa(DestAddr.sin_addr), 32);
184
185 FillPackage(IcmpBuffer, DestAddr.sin_addr.s_addr/*dstIp*/, (unsigned short)pid);
186
187 Result=sendto(IcmpSocket, IcmpBuffer, PACKAGE_SIZE, 0, (struct sockaddr*)&DestAddr, sizeof(DestAddr));
188 if(Result==SOCKET_ERROR){
189 HandleError("sendto");
190 break;
191 }
192
193 while (1){
194 tv.tv_sec=3;
195 tv.tv_usec=0;
196 FD_ZERO(&readSet);
197 FD_SET(IcmpSocket,&readSet);
198
199 int res=select(IcmpSocket+1,&readSet,NULL,NULL,&tv);
200 if(res==SOCKET_ERROR){
201 HandleError("select");
202 break;
203 }
204 if(res==0){
205 if(!bBroadcast)
206 printf("请求超时。\n");
207 break;
208 }
209 if(FD_ISSET(IcmpSocket, &readSet)){
210 memset(IcmpBuffer,0, PACKAGE_SIZE);
211 memset(&from,0,sizeof(from));
212 int len=sizeof(from);
213 if(recvfrom(IcmpSocket, IcmpBuffer, PACKAGE_SIZE,0,(struct sockaddr*) &from, &len)==SOCKET_ERROR)
214 {
215 HandleError("recvfrom");
216 break;
217 }
218
219 IPHeader *pIPHdr=(IPHeader *) IcmpBuffer;
220 ICMPHeader *pICMPHdr=(ICMPHeader*)(IcmpBuffer+sizeof(IPHeader));
221 int nTime = GetTickCount() - pICMPHdr->timestamp;
222 if(pICMPHdr->id==htons((u_short) pid)&&pICMPHdr->seq==htons((u_short) pid)
223 &&pICMPHdr->type==ICMP_ECHO_REPLY){
224 printf("来自 %s 的回复: 字节=%d time=%dms\n",inet_ntoa(from.sin_addr), Result, pIPHdr->ttl);
225 if (!bBroadcast) break;
226 }
227 }
228 }//end of while
229 Sleep(1000);
230 }
231
232 //关闭套接字
233 closesocket(IcmpSocket);
234 WSACleanup();
235 system("pause");
236 return 0;
237 }
时间： 2024-09-21 07:32:52