PHP: gethostbyname bug

Question

I am using gethostbyname() to get the ip address of domains in an application.

In some cases invalid addresses like '50.9.49' are checked also.

echo gethostbyname('50.9.49'); // returns 50.9.0.49

In this cases gethostbyname should return false or the unmodified invalid ip address. however the functions returns the modified IP address 50.9.0.49.

Looks like a bug in php. The quick fix seems to be to check for invalid numerical addresses before, are there any other suggestions?

Answer 1

PHP's gethostbyname actually uses the results of the underlying OS's gethostbyname, e.g., from Linux's netdb.h or Windows' Winsock2.h. It's those functions that actually produce the return value, not PHP.

/* {{{ php_gethostbyname */
static char *php_gethostbyname(char *name)
{
    struct hostent *hp;
    struct in_addr in;

    hp = gethostbyname(name);

    if (!hp || !*(hp->h_addr_list)) {
        return estrdup(name);
    }

    memcpy(&in.s_addr, *(hp->h_addr_list), sizeof(in.s_addr));

    return estrdup(inet_ntoa(in));
}
/* }}} */