在socket编程中，如何获取连接另一端（客户端）的ip地址，使用accept或者getpeername

原文链接：https://blog.csdn.net/gukesdo/article/details/6889594

//这段代码没有实际的功能，只是为了获取连接另一端的ip地址 

  
  
#include <iostream>
#include <winsock.h>
#include <stdio.h>

#pragma comment(lib, “wsock32”)
using namespace std;

void main()
{
int ret = 0;
WSADATA wsadata;
WORD version = MAKEWORD( 2, 0);
ret = WSAStartup(version,&wsadata);

//服务器端口创建
SOCKET m_hServerSocket;
m_hServerSocket = socket(AF_INET,SOCK_STREAM, 0);

//服务器端口绑定
SOCKADDR_IN m_addr;
m_addr.sin_family = AF_INET;
m_addr.sin_addr.S_un.S_addr = INADDR_ANY; //如果服务器是单网卡的，则就是这块网卡的ip地址；如果是多网卡，则是其中的任意一块的ip地址
m_addr.sin_port = htons( 10000);
ret = bind(m_hServerSocket,(LPSOCKADDR)&m_addr, sizeof(m_addr));

//服务器端口开始监听
ret = listen(m_hServerSocket, 10); //第二个参数指定最大申请的连接数

WSADATA cli_wsadata;
ret = WSAStartup(version,&cli_wsadata);

//客户端端口创建
SOCKET m_hClientSocket;
m_hClientSocket = socket(AF_INET,SOCK_STREAM, 0);


//客户端向服务器发送连接请求
SOCKADDR_IN m_addr1;
m_addr1.sin_family = AF_INET;
m_addr1.sin_addr.S_un.S_addr = inet_addr( “192.168.100.57”); //服务器的ip地址
m_addr1.sin_port = htons( 10000); //服务器socket的端口号
ret = connect(m_hClientSocket,(LPSOCKADDR)&m_addr1, sizeof(m_addr1)); //从客户端端口m_hClientSocket想服务器端口m_addr1发送连接请求

//0xCD,0xCD,0xCD,0XCD. 因为DEBUG为每个字节初始化0xcd(204),你未正确取得对方IP，并且你的变量未初始化的结果。
//开始使用accept和getpeername一直返回204.204.204.204的原因

SOCKET com_Sock;
SOCKADDR_IN addr_conn;
int nSize = sizeof(addr_conn);
//initialize the memory block via the memset function
memset(( void *)&addr_conn, 0, sizeof(addr_conn));

com_Sock = accept(m_hServerSocket, NULL, NULL); //从连接队列中取第一个连接进行通信
//开始时候错误是因为把第三个参数写成了(int *)(sizeof(addr_conn))，所以不会报错但是取不到正确结果！！！
//com_Sock = accept(m_hServerSocket,(SOCKADDR *)&addr_conn,&nSize); //or
getpeername(com_Sock,(SOCKADDR *)&addr_conn,&nSize);

char szPeerAddress[ 16];
//Sets buffers to a specified character.
memset(( void *)szPeerAddress, 0, sizeof(szPeerAddress));
cout << szPeerAddress << “**************” << endl;
//If no error occurs, inet_ntoa returns a character pointer to a static buffer
//containing the text address in standard ".’’ notation
strcpy(szPeerAddress,inet_ntoa(addr_conn.sin_addr));
//Copy a string.the second parameter strSource Null-terminated source string
cout << szPeerAddress << endl;
//so remember that every time use the inet_ntoa, you must copy the result by yourself
//or it will be covered by the other value
addr_conn.sin_addr.S_un.S_addr = inet_addr( “192.168.111.2”);
cout << inet_ntoa(addr_conn.sin_addr) << endl;

cout << endl;

}