Converting IP Address input by using inet_ntop() & inet_pton() (C PROGRAMMING)

c sockets inet
A CSc Student---- picture A CSc Student---- · Mar 17, 2013 · Viewed 26.1k times · Source

i'm trying to convert an IP address that's inputted by a user so that I can perform some bitwise operations on it and a address already stored in a structure. My problem is however that when the IP address is converted back the output is always 255.255.255.255. For example a input of 10.0.0.1 or 192.16.2.1 always returns 255.255.255.255.

Any help would be appreciated. THANKS 

  {
        struct sockaddr_in sa;
        char ipinput[INET_ADDRSTRLEN];

        fputs("Enter an IP Address: ", stdout);
        fflush(stdout);
        fgets(ipinput, sizeof ipinput, stdin);
        inet_pton(AF_INET, ipinput, &(sa.sin_addr));
        inet_ntop(AF_INET, &(sa.sin_addr), ipinput, INET_ADDRSTRLEN);
        printf("IP Address = \%s\ \n", ipinput);
        }

Answer

cnicutar picture cnicutar · Mar 17, 2013

You're not checking the value returned by inet_pton, you would have noticed it fails. As it turns out, it doesn't like the newline left in by fgets. Trim it:

ipinput[strlen(ipinput) - 1] = 0;

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