Question

I have this code which gets the ip of the client when the client closes or loses the connection.

char buffer[80]; 
ssize_t bread;
struct sockaddr_in peer;
socklen_t peer_len;

peer_len = sizeof(peer);

memset(&buffer, 0, sizeof(buffer));

bread = read(connectlist[listnum], buffer, 80);
if (bread < 0)
{

if(getpeername(connectlist[listnum],(struct sockaddr *) &peer, &peer_len) == -1){

        perror("getpeername() failed");
    }
            printf("Connection Reset From IP: %s\n", inet_ntoa(peer.sin_addr));

                _Print_To_File(inet_ntoa(peer.sin_addr));
                    close(connectlist[listnum]);
                        close(connectlist[listnum]);
                            connectlist[listnum] = 0;

}

if(bread == 0)
{
if(getpeername(connectlist[listnum],(struct sockaddr *) &peer, &peer_len) == -1){
        perror("getpeername() failed");
    }
            printf("Connection Closed From IP: %s\n", inet_ntoa(peer.sin_addr));

                _Print_To_File(inet_ntoa(peer.sin_addr));
                    close(connectlist[listnum]);
                            connectlist[listnum] = 0;
}

I can get the ip of the client when Connection Closed but When Connection Reset I don’t get the ip of the client. I get 0.0.0.0 on connection reset. How can i fix this. thanks,

Answer 1

You might like to use the struct sockaddr returned by the call to accept() done prior to read()ing.

Verbatim from man accept:

int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);

[…]

The argument addr is a pointer to a sockaddr structure. This
structure is filled in with the address of the peer socket, as known
to the communications layer. The exact format of the address returned
addr is determined by
the socket’s address family (see socket(2) and the respective protocol man pages). When addr is NULL, nothing is filled in; in this
case, addrlen is not used, and should also be NULL.