构造icmp包，发送给自己在同一网段的主机，使用select函数，非阻塞方式接收回包。还包括反码算术求和求首部校验和的函数。
转载请注明出处。
可能的情况
1、在线
目的主机直接回复icmp包。
2、终点不可达（发送不到目的主机）
接收到路由器或本机的icmp的终点不可达回包。
3、接受不到回包（能发送到目的主机）
能发送到目的主机，但是被目的主机的防火墙拦截了，不做回复，所以收不到回包。
代码绝大部分是老师上课的内容，自己整理了一遍，加上了一些注释：
1 // SetAvailableIP.cpp : 定义控制台应用程序的入口点。
2 //
3
4 #pragma pack(4)
5 /*
6 *编译器中提供了#pragma pack(n)来设定变量以n字节对齐方式。
7 *n字节对齐就是说变量存放的起始地址的偏移量有两种情况,
8 *第一、如果n大于等于该变量所占用的字节数，那么偏移量必须满足默认的对齐方式，
9 *第二、如果n小于该变量的类型所占用的字节数，那么偏移量为n的倍数，不用满足默认的对齐方式。
10 *结构的总大小也有个约束条件，分下面两种情况：如果n大于所有成员变量类型所占用的字节数，
11 *那么结构的总大小必须为占用空间最大的变量占用的空间数的倍数；否则必须为n的倍数。
12 */
13
14
15 #define WIN32_LEAN_AND_MEAN
16 #include "stdafx.h"
17 #include <stdlib.h>
18 #include <WINSOCK2.H>//与#include <winsock2.h>相同
19 #pragma comment(lib,"ws2_32.lib")
20
21
22 #define ICMP_ECHO 8
23 #define ICMP_ECHOREPLY 0
24
25 #define ICMP_MIN 8//// minimum 8 byte icmp packet (just header)
26 #define uchar unsigned char
27 #define uint unsigned int
28
29
30 /* ip header*/
31 typedef struct iphdr{
32 uchar h_len:4;//位域，占四个二进制位 length of header
33 uchar version:4;//Version of ip 因为位序是小端所以颠倒位置
34 uchar tos; //type of service
35 uchar total_len;//total length of packet
36 uchar ident; //unique idetifier 超出mtu，需要分片时的组号标识
37 uchar frag_and_flags;//标志3位 片偏移
38 uchar ttl; //time to live
39 uchar proto; //protocol (TCP\UDP etc)
40 uchar checksum; //IP checksum
41 uint sourceIP;
42 uint destIP;
43 }IpHeader;
44
45
46 // ICMP header
47 //
48 typedef struct _ihdr {
49 BYTE i_type;
50 BYTE i_code; /* type sub code */
51 USHORT i_cksum;
52 USHORT i_id;
53 USHORT i_seq;
54 /* This is not the std header, but we reserve space for time */
55 ULONG timestamp;
56 }IcmpHeader;
57
58
59 #define STATUS_FAILED 0xFFFF
60 #define DEF_PACKET_SIZE 32
61 #define MAX_PACKET 1024
62
63 #define xmalloc(s) HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,(s))
64 #define xfree(p) HeapFree (GetProcessHeap(),0,(p))
65
66 void fill_icmp_data(char *, int);
67 USHORT checksum(USHORT *, int);
68 void decode_resp(char *,int ,struct sockaddr_in *);
69 bool ping(IN_ADDR ip);
70
71 void Usage(char *progname){
72
73 fprintf(stderr,"Usage:\n");
74 fprintf(stderr,"%s <host> [data_size]\n",progname);
75 fprintf(stderr,"datasize can be up to 1Kb\n");
76 ExitProcess(STATUS_FAILED);
77 }
78
79
80
81 int _tmain(int argc, _TCHAR* argv[])
82 {
83 IN_ADDR ipStart,ipEnd,ip,netMask;
84 unsigned int iStart,iEnd,i;
85
86
87 WSADATA wsaData;
88 WSAStartup(MAKEWORD(2,2),&wsaData);//当一个应用程序调用WSAStartup函数时，
89 //操作系统根据请求的Socket版本来搜索相应的Socket库，然后绑定找到的Socket库到该应用程序中。
90 //以后应用程序就可以调用所请求的Socket库中的其它Socket函数了
91
92
93 ip.s_addr = inet_addr("192.168.26.155");//点分十进制转换成网络字节顺序
94 netMask.s_addr = inet_addr("255.255.255.128");
95 ipStart.s_addr = ip.s_addr & netMask.s_addr;//两个unlong,ip与掩码与 求出ip最小值
96 ipEnd.s_addr = (ipStart.s_addr & netMask.s_addr) | ~netMask.s_addr;
97
98 iStart = ntohl(ipStart.s_addr);//网络自己顺序转换成主机字节顺序
99 iEnd = ntohl(ipEnd.s_addr);
100
101 for(i = iStart+2;i<iEnd;i++)//iStart不可用，iStart+1一般做默认网关地址，iStart+2开始
102 {
103 ip.s_addr = htonl(i);
104 printf("%s\n",inet_ntoa(ip));//in_addr（点分十进制）转换成字符串
105 ping(ip);
106 }
107 WSACleanup();
108 return 0;
109 }
110
111
112 bool ping(IN_ADDR ip)//ping程序
113 {
114 SOCKET sockRaw;
115 struct sockaddr_in dest,from;
116 int bread,datasize;
117 int fromlen = sizeof(from);
118 int timeout = 1000;
119 char *dest_ip;
120 char *icmp_data;
121 char *recvbuf;
122 unsigned int addr = 0;
123 USHORT seq_no = 0;
124
125 struct timeval tv;
126 tv.tv_sec = 3;
127 tv.tv_usec = 0;
128
129
130 sockRaw = WSASocket(AF_INET,SOCK_RAW,IPPROTO_ICMP,NULL,0,0);
131
132 if(sockRaw == INVALID_SOCKET)
133 {
134 fprintf(stderr,"WSASocket() failed:%d\n",WSAGetLastError());
135 ExitProcess(STATUS_FAILED);
136 }
137
138 bread = setsockopt(sockRaw,SOL_SOCKET,SO_RCVTIMEO,(char*)&timeout,sizeof(timeout));//设置1秒超时时间
139
140 if(bread == SOCKET_ERROR) {
141 fprintf(stderr,"failed to set recv timeout: %d\n",WSAGetLastError());
142 ExitProcess(STATUS_FAILED);
143 }
144
145 timeout = 1000;
146 bread = setsockopt(sockRaw,SOL_SOCKET,SO_SNDTIMEO,(char*)&timeout,
147 sizeof(timeout));
148 if(bread == SOCKET_ERROR) {
149 fprintf(stderr,"failed to set send timeout: %d\n",WSAGetLastError());
150 ExitProcess(STATUS_FAILED);
151 }
152
153 memset(&dest,0,sizeof(dest));//初始化
154
155 dest.sin_addr = ip;
156 dest.sin_family = AF_INET;
157 dest_ip = inet_ntoa(dest.sin_addr);
158
159 datasize = DEF_PACKET_SIZE;
160 datasize += sizeof(IcmpHeader);
161
162 icmp_data = (char*)xmalloc(MAX_PACKET);
163 recvbuf = (char*)xmalloc(MAX_PACKET);
164
165
166 if (!icmp_data) {
167 fprintf(stderr,"HeapAlloc failed %d\n",GetLastError());
168 ExitProcess(STATUS_FAILED);
169 }
170
171
172 memset(icmp_data,0,MAX_PACKET);
173 fill_icmp_data(icmp_data,datasize);
174
175
176 //while(1) {
177 int bwrote;
178
179 ((IcmpHeader*)icmp_data)->i_cksum = 0;
180 ((IcmpHeader*)icmp_data)->timestamp = GetTickCount();
181
182 ((IcmpHeader*)icmp_data)->i_seq = seq_no++;
183 ((IcmpHeader*)icmp_data)->i_cksum = checksum((USHORT*)icmp_data,
184 datasize);
185
186 bwrote = sendto(sockRaw,icmp_data,datasize,0,(struct sockaddr*)&dest,
187 sizeof(dest));
188
189 if (bwrote == SOCKET_ERROR){
190 if (WSAGetLastError() == WSAETIMEDOUT) {
191 printf("timed out\n");
192 //continue;
193 }
194 fprintf(stderr,"sendto failed: %d\n",WSAGetLastError());
195 ExitProcess(STATUS_FAILED);
196 }
197 if (bwrote < datasize ) {
198 fprintf(stdout,"Wrote %d bytes\n",bwrote);
199 }
200
201
202
203 fd_set socketset;
204 memset(&socketset, 0, sizeof(socketset));
205 socketset.fd_count = 1;
206 socketset.fd_array[0] = sockRaw;
207 bread = select(0, &socketset, NULL, NULL, &tv);//非阻塞方式接收数据，接收不到显示超时继续ping后面的IP
208 if (bread == 0){
209 //if (WSAGetLastError() == WSAETIMEDOUT) {
210 printf("recv timed out\n");
211 //continue;
212 //}
213 //fprintf(stderr,"recvfrom failed: %d\n",WSAGetLastError());
214 //ExitProcess(STATUS_FAILED);
215 }
216 else{
217 bread = recvfrom(sockRaw,recvbuf,MAX_PACKET,0,(struct sockaddr*)&from,
218 &fromlen);
219 decode_resp(recvbuf,bread,&from);
220 }
221 //Sleep(1000);
222
223 //}
224
225 xfree(icmp_data);
226 xfree(recvbuf);
227
228 }
229
230
231 USHORT checksum(USHORT *buffer, int size) {//校验和
232
233 unsigned long cksum=0;
234
235 while(size >1) {
236 cksum+=*buffer++;
237 size -=sizeof(USHORT);
238 }
239
240 if(size ) {
241 cksum += *(UCHAR*)buffer;
242 }
243
244 cksum = (cksum >> 16) + (cksum & 0xffff);//反码算术运算求和
245 cksum += (cksum >>16);//最多进一位，右移加上进位，不可能再次产生进位 比如99+99 =198 98+1=99 不会继续产生进位
246 return (USHORT)(~cksum);
247 }
248
249 /*
250 Helper function to fill in various stuff in our ICMP request.
251 */
252 void fill_icmp_data(char * icmp_data, int datasize){
253
254 IcmpHeader *icmp_hdr;
255 char *datapart;
256
257 icmp_hdr = (IcmpHeader*)icmp_data;
258
259 icmp_hdr->i_type = ICMP_ECHO;
260 icmp_hdr->i_code = 0;
261 icmp_hdr->i_id = (USHORT)GetCurrentProcessId();
262 icmp_hdr->i_cksum = 0;
263 icmp_hdr->i_seq = 0;
264
265 datapart = icmp_data + sizeof(IcmpHeader);//截取数据部分
266 //
267 // Place some junk in the buffer.
268 //
269 memset(datapart,‘E‘, datasize - sizeof(IcmpHeader));//填充数据
270 }
271
272 /*
273 The response is an IP packet. We must decode the IP header to locate
274 the ICMP data
275 */
276 void decode_resp(char *buf, int bytes,struct sockaddr_in *from) {
277
278 IpHeader *iphdr;
279 IcmpHeader *icmphdr;
280 unsigned short iphdrlen;
281
282 iphdr = (IpHeader *)buf;
283
284 iphdrlen = iphdr->h_len * 4; // number of 32-bit words *4 = bytes
285
286 if (bytes < iphdrlen + ICMP_MIN) {
287 printf("Too few bytes from %s\n",inet_ntoa(from->sin_addr));
288 }
289
290 icmphdr = (IcmpHeader*)(buf + iphdrlen);
291
292 if (icmphdr->i_type != ICMP_ECHOREPLY) {
293 fprintf(stderr,"non-echo type %d recvd\n",icmphdr->i_type);
294 return;
295 }
296 if (icmphdr->i_id != (USHORT)GetCurrentProcessId()) {
297 fprintf(stderr,"someone else‘s packet!\n");
298 return ;
299 }
300 printf("%d bytes from %s:",bytes, inet_ntoa(from->sin_addr));
301 printf(" icmp_seq = %d. ",icmphdr->i_seq);
302 printf(" time: %d ms ",GetTickCount()-icmphdr->timestamp);//GetTickCount()操作系统从启动经过的毫秒数
303 printf("\n");
304
305 }
时间： 2024-10-12 09:48:26