Question

在以C++的socket编的UDP通信程序中，如何获取对方(client)的IP地址(xxx.xxx.xxx.xxx格式)？

// 请帮忙解决以下打着三个问号？？？的内容
//

#include "stdafx.h"
#define BUF_SZIE 64
#include "winsock2.h"
#pragma comment(lib, "ws2_32.lib")

int main(int argc, char* argv[])
{

WSADATA wsd; //WSADATA变量
SOCKET s; //套接字
SOCKADDR_IN servAddr; //服务器地址
char buf[BUF_SZIE]; //接收数据缓冲区

//初始化套结字动态库
if (WSAStartup(MAKEWORD(2,2), &wsd) != 0)
{
printf("WSAStartup failed!\n");
return 1;
}

//创建套接字
s = socket(AF_INET, SOCK_DGRAM, 0);
if (s == INVALID_SOCKET)
{
printf("socket() failed; %d\n", WSAGetLastError());
WSACleanup();//释放套接字资源
return 1;
}

int nErrCode; //返回值
int nBufLen; //接收数据缓冲区大小
int nOptlen = sizeof(nBufLen);
//获取接收数据缓冲区大小
nErrCode = getsockopt(s, SOL_SOCKET, SO_RCVBUF,(char*)&nBufLen, &nOptlen);
if (SOCKET_ERROR == nErrCode)
{
//处理失败
}

//设置接收数据缓冲区为原来的10倍
nBufLen *= 10;
nErrCode = setsockopt(s, SOL_SOCKET, SO_RCVBUF,(char*)&nBufLen, nOptlen);
if (SOCKET_ERROR == nErrCode)
{
//失败处理
}

//检查设置系统接收数据缓冲区是否成功
int uiNewRcvBuf;
getsockopt(s, SOL_SOCKET, SO_RCVBUF,(char*)&uiNewRcvBuf, &nOptlen);
if (SOCKET_ERROR == nErrCode || uiNewRcvBuf != nBufLen)
{
//失败处理
}

//服务器地址
servAddr.sin_family = AF_INET;
servAddr.sin_port = htons((short)5000); //端口
servAddr.sin_addr.s_addr = htonl(INADDR_ANY); //IP

//绑定
if (bind(s, (SOCKADDR *)&servAddr, sizeof(servAddr)) == SOCKET_ERROR)
{
printf("bind() failed: %d\n", WSAGetLastError());
closesocket(s); //关闭套接字
WSACleanup(); //释放套接字资源
return 1;
}

//接收数据
SOCKADDR_IN clientAddr;
int nClientLen = sizeof(clientAddr);
ZeroMemory(buf, BUF_SZIE);
if(recvfrom(s, buf, BUF_SZIE, 0, (SOCKADDR*)&clientAddr, &nClientLen) == SOCKET_ERROR)
{
printf("recvfrom() failed: %d\n", WSAGetLastError());
closesocket(s); //关闭套接字
WSACleanup(); //释放套接字资源
return 1;
}

printf("%s\n", buf);//输出client发出的内容

//？？？输出client的IP地址

//？？？输出client的端口号

closesocket(s); //关闭套接字
WSACleanup(); //释放套接字资源
return 0;
}

Answer 1

printf("%s\n",inet_ntoa(clientaddr.sin_addr))
printf("%d\n",clientaddr.sin_port)