在我的C:\Windows\System32\drivers\etc\service文件中,我看到了
echo 7/tcpecho 7/udp
所以我写了一个程序来测试getservbyname
#include <stdio.h>
#include <winsock2.h>
#include <iostream>
#pragma comment(lib,"ws2_32.lib") // winsock library
using namespace std;
int main(int argc, char *argv[])
{
WSADATA wsa;
SOCKET s;
sockaddr_in server;
servent *serverInfo;
cout << "Initializing Winsock...." << endl;
if (WSAStartup(MAKEWORD(2,2), &wsa) != 0) {
cout << "Failed. Error code: " << WSAGetLastError();
return 1;
}
cout << "initialized." << endl;
serverInfo = getservbyname("echo", "tcp");
cout << "service echo:: s_name is " << serverInfo->s_name << endl;
cout << "service echo:: s_aliases is " << serverInfo->s_aliases << endl;
cout << "service echo:: s_port is " << serverInfo->s_port << endl;
cout << "service echo:: s_proto is " << serverInfo->s_proto << endl;
return 0;
}
当我运行它时,下面是显示的结果:
Initializing Winsock....
initialized.
service echo:: s_name is echo
service echo:: s_aliases is 00724F08
service echo:: s_port is 1792
service echo:: s_proto is tcp
我的问题是为什么s_port是1792而不是7?我在档案服务中找不到1792。有人能解释一下吗?非常感谢。
7*256=1792
它是按网络字节顺序排列的。请尝试打印ntohs(serverInfo->s_port)。
如果您要使用它来构建sockaddr_in
,您可以直接将它复制到sin_port
,因为这也是网络字节顺序。