尝试侦听端口时没有任何反应

Question

I'm trying to write a very simple program that just listens on a predefined port.here is the code:

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
int main(int argc, char *argv[])
{
int sockfd;
struct addrinfo hints,*res;
memset(&hints,0,sizeof(hints));
hints.ai_family=AF_UNSPEC;
hints.ai_socktype=SOCK_STREAM;
hints.ai_flags=AI_PASSIVE;

getaddrinfo(NULL,"5050",&hints,&res); 
sockfd=socket(res->ai_family,res->ai_socktype,res->ai_protocol);
bind(sockfd,res->ai_addr,res->ai_addrlen); //returns 0(success)
listen(sockfd,1);//returns 0(success)
return 0;
}

but there is no sign of listening anywhere.i used netstat -l command to check if the program is listening or not.

Answer 1

You are missing an accept() call.

Also you are exiting from the program.

The socket would be active for the duration of your process only.

Answer 2

You have most of the parts but neglected to call accept(). Without that your program probably just returns quickly without doing anything useful.

Answer 3

Your program does listen, but it exits immediately, so anything it has done vanishes into the ether. If you want to accept connections you will have to call accept() .

You also need to error-check every one of those calls. You can't just assume they all succeeded.