illumos gate

In the past we made some changes to the behaviour of inet_pton in the kernel, as well. We retained the old behaviour for binary modules that could not be rebuilt, and used #pragma redefine_extname to enable the fixed behaviour for newly compiled modules. We could do the same thing here, with a structure like:

#define    ERROR_BAD_ADDRESS    "<badaddr>" 
#define    ERROR_BAD_FAMILY    "<badfamily>" 

#define    IPV4_PAD        "%03d.%03d.%03d.%03d" 
#define    IPV4_NOPAD        "%d.%d.%d.%d" 

#define    UC(b)            (((int)b) & 0xff)

/*
 * Common implementation.
 */
static char *
inet_ntop_common(int af, const void *addr, char *buf, int addrlen, boolean_t ipv4_padding)
{
        in6_addr_t *v6addr;
        uchar_t *v4addr;
        char *caddr;

    VERIFY(buf != NULL);
    VERIFY(addr != NULL);

    switch (af) {
    case AF_INET:
        VERIFY(addrlen >= INET_ADDRSTRLEN);
        v4addr = (uchar_t *)addr;
        (void) sprintf(buf, ipv4_padding ? IPV4_PAD : IPV4_NOPAD,
            UC(v4addr[0]), UC(v4addr[1]), UC(v4addr[2]), UC(v4addr[3]));
        return (buf);

    ...

    default:
        return (ERROR_BAD_FAMILY);
    }
}

/*
 * New wrapper.  Using "#pragma redefine_extname" in the header to make this the
 * function that new users of "inet_ntop()" get.
 */
char *
_inet_ntop(int af, const void *addr, char *buf, int addrlen)
{
    return (inet_ntop_common(af, addr, buf, addrlen, B_FALSE));
}

/*
 * Old wrapper.
 */
char *
inet_ntop(int af, const void *addr, char *buf, int addrlen)
{
    static char local_buf[INET6_ADDRSTRLEN];

    ASSERT(buf != NULL);
    if (buf == NULL) {
        buf = local_buf;
    }

    return (inet_ntop_common(af, addr, buf, addrlen, B_TRUE));
}

Noting, of course, that if we're going to do this then we should scrub out all of the latent sadness in the current implementation (e.g. the static buffer, out-of-date comments, poorly defined macros, etc).