Windowsping源码

需要测试外⽹的联通性，想到了⽤ping。⽹上下载了ping的源代码，调试下整理如下：

1 /******************************************************************************\\ 2 * ping.c - Simple ping utility using SOCK_RAW 3 *

4 * This is a part of the Microsoft Source Code Samples. 5 * Copyright 1996-1997 Microsoft Corporation. 6 * All rights reserved.

7 * This source code is only intended as a supplement to

8 * Microsoft Development Tools and/or WinHelp documentation. 9 * See these sources for detailed information regarding the 10 * Microsoft samples programs.

11 \\******************************************************************************/ 12

13 #pragma pack(4) 14

15 #define WIN32_LEAN_AND_MEAN 16 #include 17 #include 18 #include

19 #pragma comment(lib,\"ws2_32.lib\") 20

21 #define ICMP_ECHO 8

22 #define ICMP_ECHOREPLY 0 23

24 #define ICMP_MIN 8 // minimum 8 byte icmp packet (just header) 25

26 /* The IP header */ 27 typedef struct iphdr 28 {

29 unsigned int h_len:4; // length of the header 30 unsigned int version:4; // Version of IP 31 unsigned char tos; // Type of service

32 unsigned short total_len; // total length of the packet 33 unsigned short ident; // unique identifier 34 unsigned short frag_and_flags; // flags 35 unsigned char ttl;

36 unsigned char proto; // protocol (TCP, UDP etc) 37 unsigned short checksum; // IP checksum 38 unsigned int sourceIP; 39 unsigned int destIP; 40 }IpHeader; 41 42 //

43 // ICMP header 44 //

45 typedef struct _ihdr {

46 BYTE i_type; //消息类型

47 BYTE i_code; //代码 /* type sub code */ 48 USHORT i_cksum; //校验和 49 USHORT i_id; //ID号 50 USHORT i_seq; //序列号

51 ULONG timestamp; //时间戳 /* This is not the std header, but we reserve space for time */ 52 }IcmpHeader; //ICMP报⽂ 包括报头和数据 53

54 #define STATUS_FAILED 0xFFFF 55 #define DEF_PACKET_SIZE 32 56 #define MAX_PACKET 1024 57

58 #define xmalloc(s) HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,(s)) 59 #define xfree(p) HeapFree (GetProcessHeap(),0,(p)) 60

61 void fill_icmp_data(char *, int);

62 USHORT checksum(USHORT *, int);

63 void decode_resp(char *,int ,struct sockaddr_in *); 64

65 int main(int argc, char **argv) 66 {

67 WSADATA wsaData; 68 SOCKET sockRaw; 69 struct sockaddr_in dest; 70 struct hostent * hp; 71 int bread,datasize; 72 int timeout = 1000; 73 char *dest_ip; 74 char *icmp_data; 75 char *recvbuf;

76 unsigned int addr=0; 77 USHORT seq_no = 0; 78 struct sockaddr_in from;

79 int fromlen = sizeof(from); 80

81 if (WSAStartup(MAKEWORD(2,1),&wsaData) != 0) 82 {

83 fprintf(stderr,\"WSAStartup failed: %d\\n\",GetLastError()); 84 ExitProcess(STATUS_FAILED); 85 } 86 87 /*

88 为了使⽤发送接收超时设置(即设置SO_RCVTIMEO, SO_SNDTIMEO)， 89 // 必须将标志位设为WSA_FLAG_OVERLAPPED ! 90 */

91 sockRaw = WSASocket (AF_INET, SOCK_RAW, IPPROTO_ICMP, NULL, 0,WSA_FLAG_OVERLAPPED); //建⽴⼀个原始套接字 92 //sockRaw = WSASocket (AF_INET, SOCK_RAW, IPPROTO_ICMP, NULL, 0,0); 93

94 if (sockRaw == INVALID_SOCKET) 95 {

96 fprintf(stderr,\"WSASocket() failed: %d\\n\",WSAGetLastError()); 97 ExitProcess(STATUS_FAILED); 98 } 99

100 timeout = 1000; //设置接收超时时间

101 bread = setsockopt(sockRaw,SOL_SOCKET,SO_RCVTIMEO,(char*)&timeout, sizeof(timeout)); //RECVTIMEO是接收超时时间102 if(bread == SOCKET_ERROR) 103 {

104 fprintf(stderr,\"failed to set recv timeout: %d\\n\",WSAGetLastError()); 105 ExitProcess(STATUS_FAILED); 106 }

107 108 timeout = 1000; //设置发送超时时间

109 bread = setsockopt(sockRaw,SOL_SOCKET,SO_SNDTIMEO,(char*)&timeout, sizeof(timeout)); //SNDTIMEO是发送超时时间 110 if(bread == SOCKET_ERROR) 111 {

112 fprintf(stderr,\"failed to set send timeout: %d\\n\",WSAGetLastError()); 113 ExitProcess(STATUS_FAILED); 114 }

115 memset(&dest,0,sizeof(dest)); //⽬标地址清零116

117 hp = gethostbyname(\"www.baidu.com\"); //通过域名或者主机名获取IP地址118 if (!hp) //失败返回NULL119 {

120 ExitProcess(STATUS_FAILED);121 }122 else123 {

124 addr = inet_addr(\"14.215.177.37\"); //www.baidu.com的ip地址125 }126

127 if ((!hp) && (addr == INADDR_NONE)) //既不是域名也不是点分⼗进制的IP地址 128 {

129 ExitProcess(STATUS_FAILED);130 }131

132 if (hp != NULL) //获取的是域名

133 memcpy(&(dest.sin_addr),hp->h_addr,hp->h_length); //从hostent得到的对⽅ip地址134 else

135 dest.sin_addr.s_addr = addr; 136

137 if (hp)

138 dest.sin_family = hp->h_addrtype; //sin_family不是⼀定只能填AF_INET吗？139 else

140 dest.sin_family = AF_INET; 141

142 dest_ip = inet_ntoa(dest.sin_addr); //⽬标IP地址143

144 datasize = DEF_PACKET_SIZE; //ICMP包数据⼤⼩设定为32145

146 datasize += sizeof(IcmpHeader); //另外加上ICMP包的包头 其实包头占12个字节147

148 icmp_data = (char *)xmalloc(MAX_PACKET);//发送icmp_data数据包内存149 recvbuf = (char *)xmalloc(MAX_PACKET); //存放接收到的数据150

151 if (!icmp_data) //分配内存152 {

153 ExitProcess(STATUS_FAILED); 154 }155

156 memset(icmp_data,0,MAX_PACKET);

157 fill_icmp_data(icmp_data,datasize); //只填充了ICMP包158

159 fprintf(stdout,\"\\nPinging %s ....\\n\\n\",dest_ip); 160

161 while(1)162 {

163 int bwrote; 164

165 ((IcmpHeader*)icmp_data)->i_cksum = 0;

166 ((IcmpHeader*)icmp_data)->timestamp = GetTickCount(); //时间戳167

168 ((IcmpHeader*)icmp_data)->i_seq = seq_no++; //ICMP的序列号

169 ((IcmpHeader*)icmp_data)->i_cksum = checksum((USHORT*)icmp_data, datasize); //icmp校验位 170

171 //下⾯这个函数的问题是 发送数据只是ICMP数据包，⽽接收到的数据时包含ip头的 也就是发送和接收不对等172 //问题是sockRaw 设定了协议为 IPPROTO_ICMP

173 bwrote = sendto(sockRaw,icmp_data,datasize,0,(struct sockaddr*)&dest, sizeof(dest)); 174 if (bwrote == SOCKET_ERROR)175 {

176 if (WSAGetLastError() == WSAETIMEDOUT) //发送时间超时177 {

178 printf(\"timed out\\n\"); 179 continue; 180 } 181

182 fprintf(stderr,\"sendto failed: %d\\n\",WSAGetLastError()); 183 ExitProcess(STATUS_FAILED); 184 }185

186 if (bwrote < datasize ) 187 {

188 fprintf(stdout,\"Wrote %d bytes\\n\",bwrote); 189 } 190

191 bread = recvfrom(sockRaw,recvbuf,MAX_PACKET,0,(struct sockaddr*)&from, &fromlen); 192 if (bread == SOCKET_ERROR)193 {

194 if (WSAGetLastError() == WSAETIMEDOUT)195 {

196 printf(\"timed out\\n\");197 continue;198 }

199 fprintf(stderr,\"recvfrom failed: %d\\n\",WSAGetLastError()); 200 ExitProcess(STATUS_FAILED); 201 }

202 decode_resp(recvbuf,bread,&from); 203

204 Sleep(1000);205 }206

207 WSACleanup(); 208 system(\"pause\");209

210 return 0; 211 } 212 213 /*

214 The response is an IP packet. We must decode the IP header to locate 215 the ICMP data 216 */

217 void decode_resp(char *buf, int bytes,struct sockaddr_in *from) 218 {

219 IpHeader *iphdr;

220 IcmpHeader *icmphdr; 221 unsigned short iphdrlen; 222

223 iphdr = (IpHeader *)buf; //接收到的数据就是原始的IP数据报224

225 iphdrlen = iphdr->h_len * 4 ; // number of 32-bit words *4 = bytes 226

227 if (bytes < iphdrlen + ICMP_MIN) 228 {

229 printf(\"Too few bytes from %s\\n\",inet_ntoa(from->sin_addr)); 230 } 231

232 icmphdr = (IcmpHeader*)(buf + iphdrlen); 233

234 if(icmphdr->i_type == 3)235 {

236 printf(\"network unreachable -- Response from %s.\\n\",inet_ntoa(from->sin_addr));237 return ;238 }239

240 if (icmphdr->i_id != (USHORT)GetCurrentProcessId())241 {

242 fprintf(stderr,\"someone else's packet!\\n\"); 243 return ; 244 }

245 printf(\"%d bytes from %s:\",bytes, inet_ntoa(from->sin_addr)); 246 printf(\" icmp_seq = %d \",icmphdr->i_seq);

247 printf(\" time: %d ms \",GetTickCount()-icmphdr->timestamp); 248 printf(\" ttl: %d\",iphdr->ttl);249 printf(\"\\n\"); 250 } 251

252 //完成ICMP的校验

253 USHORT checksum(USHORT *buffer, int size) 254 {

255 unsigned long cksum=0; 256

257 while(size >1) 258 {

259 cksum+=*buffer++;

260 size -=sizeof(USHORT); 261 } 262

263 if(size ) 264 {

265 cksum += *(UCHAR*)buffer; 266 } 267

268 cksum = (cksum >> 16) + (cksum & 0xffff); 269 cksum += (cksum >>16); 270 return (USHORT)(~cksum); 271 }272 273 /*

274 Helper function to fill in various stuff in our ICMP request. 275 */

276 void fill_icmp_data(char * icmp_data, int datasize){ 277

278 IcmpHeader *icmp_hdr; 279 char *datapart; 280

281 icmp_hdr = (IcmpHeader*)icmp_data; 282

283 icmp_hdr->i_type = ICMP_ECHO; //ICMP_ECHO要求收到包的主机回复此ICMP包284 icmp_hdr->i_code = 0;

285 icmp_hdr->i_id = (USHORT)GetCurrentProcessId(); //id填当前进程的id286 icmp_hdr->i_cksum = 0; 287 icmp_hdr->i_seq = 0; 288

289 datapart = icmp_data + sizeof(IcmpHeader); 290 //

291 // Place some junk in the buffer. 292 //

293 memset(datapart,'E', datasize - sizeof(IcmpHeader)); //填充了⼀些废物294 }

我下到代码的时候，第91⾏创建原始套接字的地⽅原本是被屏蔽的第92⾏，区别在与创建套接字时赋予的标志位不⼀样。 WSASocket函数的定义如下：

SOCKET WSASocket (　　int af, 　　int type, 　　int protocol,

　　LPWSAPROTOCOL_INFO lpProtocolInfo, 　　GROUP g,

　　DWORD dwFlags 　　);

af：[in]⼀个地址族规范。⽬前仅⽀持AF_INET格式，亦即ARPA Internet地址格式。 type：新套接⼝的类型描述。

protocol：套接⼝使⽤的特定协议，如果调⽤者不愿指定协议则定为0。

lpProtocolInfo：⼀个指向PROTOCOL_INFO结构的指针，该结构定义所创建套接⼝的特性。如果本参数⾮零，则前三个参数（af, type,protocol）被忽略。

g：保留给未来使⽤的套接⼝组。套接⼝组的标识符。 iFlags：套接⼝属性描述。

具体详细介绍看微软官⽅介绍⽂档：https://msdn.microsoft.com/en-us/library/ms742212(VS.85).aspx