VC++实现软路由层面的ping

大家都知道ping ,如果是网络层该怎么实现呢，代码实现如下

#include "../common/initsock.h"#include "../common/protoinfo.h"#include "../common/comm.h"#include <stdio.h>CInitSock theSock;typedef struct icmp_hdr{    unsigned char   icmp_type;// 消息类型    unsigned char   icmp_code;// 代码    unsigned short  icmp_checksum;// 校验和// 下面是回显头    unsigned short  icmp_id;// 用来惟一标识此请求的ID号，通常设置为进程ID    unsigned short  icmp_sequence;// 序列号    unsigned long   icmp_timestamp; // 时间戳} ICMP_HDR, *PICMP_HDR;int main(){// 目的IP地址，即要Ping的IP地址char szDestIp[] = "10.16.115.178";// 127.0.0.1// 创建原始套节字SOCKET sRaw = ::socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);// 设置接收超时SetTimeout(sRaw, 1000, TRUE);// 设置目的地址SOCKADDR_IN dest;dest.sin_family = AF_INET;dest.sin_port = htons(0);dest.sin_addr.S_un.S_addr = inet_addr(szDestIp);// 创建ICMP封包char buff[sizeof(ICMP_HDR) + 32];ICMP_HDR* pIcmp = (ICMP_HDR*)buff;// 填写ICMP封包数据pIcmp->icmp_type = 8;// 请求一个ICMP回显pIcmp->icmp_code = 0;pIcmp->icmp_id = (USHORT)::GetCurrentProcessId();pIcmp->icmp_checksum = 0;pIcmp->icmp_sequence = 0;// 填充数据部分，可以为任意memset(&buff[sizeof(ICMP_HDR)], 'E', 32);// 开始发送和接收ICMP封包USHORTnSeq = 0;char recvBuf[1024];SOCKADDR_IN from;int nLen = sizeof(from);while(TRUE){static int nCount = 0;int nRet;if(nCount++ == 4)break;pIcmp->icmp_checksum = 0;pIcmp->icmp_timestamp = ::GetTickCount();pIcmp->icmp_sequence = nSeq++;pIcmp->icmp_checksum = checksum((USHORT*)buff, sizeof(ICMP_HDR) + 32);nRet = ::sendto(sRaw, buff, sizeof(ICMP_HDR) + 32, 0, (SOCKADDR *)&dest, sizeof(dest));if(nRet == SOCKET_ERROR){printf(" sendto() failed: %d \n", ::WSAGetLastError());return -1;}nRet = ::recvfrom(sRaw, recvBuf, 1024, 0, (sockaddr*)&from, &nLen);if(nRet == SOCKET_ERROR){if(::WSAGetLastError() == WSAETIMEDOUT){printf(" timed out\n");continue;}printf(" recvfrom() failed: %d\n", ::WSAGetLastError());return -1;}// 下面开始解析接收到的ICMP封包int nTick = ::GetTickCount();if(nRet < sizeof(IPHeader) + sizeof(ICMP_HDR)){printf(" Too few bytes from %s \n", ::inet_ntoa(from.sin_addr));}// 接收到的数据中包含IP头，IP头大小为20个字节，所以加20得到ICMP头ICMP_HDR* pRecvIcmp = (ICMP_HDR*)(recvBuf + 20); // (ICMP_HDR*)(recvBuf + sizeof(IPHeader));if(pRecvIcmp->icmp_type != 0)// 回显{printf(" nonecho type %d recvd \n", pRecvIcmp->icmp_type);return -1;}if(pRecvIcmp->icmp_id != ::GetCurrentProcessId()){printf(" someone else's packet! \n");return -1;}printf(" %d bytes from %s:", nRet, inet_ntoa(from.sin_addr));printf(" icmp_seq = %d. ", pRecvIcmp->icmp_sequence);printf(" time: %d ms", nTick - pRecvIcmp->icmp_timestamp);printf(" \n");::Sleep(1000);}return 0;}