CODEWITHSUNDEEP
linuxsocketsnetwork-programming
gln
gln

Reputation: 1031

Get socket peer IPS linux

In my linux c++ application I want to write a function hat will check for a giving socket if the socket peer is local. I know how to retrive all the local IPs, but I don't know how to check if the socket peer is from the local IPS list.

any help? with code please!!

10x

Upvotes: 0

Views: 594

Answers (1)

D.Shawley
D.Shawley

Reputation: 59563

You are looking for getpeername() for the peer side of the socket. Use getsockname() for the local side of the socket. The following snippet will retrieve a sockets local and peer addresses in the Internet domain. I'll leave it up to you to extend it to handle other types of sockets if you have a need. I included some rudimentary error checking as a bonus.

int
get_addresses(int sd, struct sockaddr_in *local_ptr,
              struct sockaddr_in *peer_ptr)
{
    int rc = -1;
    if (local_ptr == NULL || peer_ptr == NULL) {
        errno = EFAULT;
        return rc;
    }
    if (sd == -1) {
        errno = EBADF;
        return rc;
    }
    if (local_ptr->sin_family != AF_INET || peer_ptr->sin_family != AF_INET) {
        errno = EINVAL;
        return rc;
    }

    rc = getsockname(sd, (struct sockaddr*)local_ptr,
                     sizeof(struct sockaddr_in));
    if (rc == 0) {
        rc = getpeername(sd, (struct sockaddr*)local_ptr,
                         sizeof(struct sockaddr_in));
        if (rc < 0) {
            if (errno == ENOTCONN) {
                /* socket is not connected so zero out the peer side */
                peer_ptr->sin_len = sizeof(struct sockaddr_in);
                peer_ptr->sin_family = AF_INET;
                peer_ptr->sin_port = 0;
                peer_ptr->sin_addr.s_addr = INADDR_NONE;
                rc = 0;
            }
        }
    }
    return rc;
}

Upvotes: 1

Related Questions