use getsockname to get ip and port

get_ip_v1.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SERVER_ADDR "172.217.160.99"
#define SERVER_PORT 80

int main()
{
    char myIP[16];
    unsigned int myPort;
    struct sockaddr_in server_addr, my_addr;
    int sockfd;

    // Connect to server
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("Can't open stream socket.");
        exit(-1);
    }

    // Set server_addr
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(SERVER_ADDR);
    server_addr.sin_port = htons(SERVER_PORT);

    // Connect to server
    if (connect(sockfd, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0) {
        perror("Connect server error");
        close(sockfd);
        exit(-1);
    }

    // Get my ip address and port
    bzero(&my_addr, sizeof(my_addr));
    socklen_t len = sizeof(my_addr);
    getsockname(sockfd, (struct sockaddr *) &my_addr, &len);
    inet_ntop(AF_INET, &my_addr.sin_addr, myIP, sizeof(myIP));
    myPort = ntohs(my_addr.sin_port);

    printf("Local ip address: %s\n", myIP);
    printf("Local port : %u\n", myPort);

    return 0;
}

in c++, I was getting a conversion error for int len, but fixed it by socklen_t len = sizeof(my_addr);

in c++, I was getting a conversion error for int len, but fixed it by socklen_t len = sizeof(my_addr);

updated.

I think there's a missing close(sockfd) at the end of the function.

so for example:

    getsockname(sockfd, (struct sockaddr *) &my_addr, &len);
    inet_ntop(AF_INET, &my_addr.sin_addr, myIP, sizeof(myIP));
    myPort = ntohs(my_addr.sin_port);
    close(sockfd);