用winsock套接字API获取端口号 [英] Retrieving port number using winsock sockets API
问题描述
虽然我得到了来自下面的code段的端口号为非零值,返回端口值不匹配的值端口用于建立套接字:
Although I do get a non-zero value for port number from the code segment below, the value returned for port does not match the value for port used to establish the socket:
#include <winsock2.h>
int main(void)
{
SOCKADDR_IN server;
WSADATA wsa;
SOCKET s;
DWORD dwTime = 1000;
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0)
{
//handle error
}
if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET)
{
//handle error
}
if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, (const char*)&dwTime, sizeof(dwTime)) == SOCKET_ERROR)
{
//handle error
}
server.sin_addr.s_addr = inet_addr("127.0.0.1");
server.sin_family = AF_INET;
server.sin_port = htons( 5000 );
//Connect to server
if(connect(s , (struct sockaddr *)&server , sizeof(server)) == SOCKET_ERROR)
{
//handle error
}
//read port number
size_t lensin = sizeof(server);
if (getsockname(s, (struct sockaddr *)&server, &lensin) == SOCKET_ERROR)
perror("getsockname");
else
{
printf("port number, no byte order reversal: %u\n", server.sin_port);
printf("port number, with byte order reversal: %u\n", ntohs(server.sin_port));
}
return 0;
}
有关端口是5000,我得到以下值:结果
For port 5000, I get the following value:
带或不带字节顺序反转(使用 ntohs和()
),该值仍然不一样的。我怎样才能读取用来建立在首位的连接端口号的整数值?
With or without byte order reversal (using ntohs()
), the value is still not the same. How can I read the integer value for port number that was used to establish the connection in the first place?
推荐答案
getsockname()返回本地端口号。由于您的插座不绑定到特定的本地端口,当你叫连接(),随机临时端口得到选择,端口56179。
getsockname() returns the local port number. Since your socket was not bound to a specific local port when you called connect(), a random ephemeral port got chosen, port 56179.
如果您需要的端口号您连接到使用的 getpeername()
If you want the port number you connected to, use getpeername()
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