Trying to write fast non dependency IP4 string validator for embedded system, It should counts leading zeros, values over 255 and other corrupted strings. Not sure if I missed something. Сan you guys take a look:

// Return 0 on error, store result to segs, if segs != 0.
int is_valid_ip4(const char *str, unsigned char* segs)
{
    int dots = 0;   // Dot count.
    int chcnt = 0;  // Character count within segment.
    int accum = 0;  // Accumulator for segment.

    // Catch NULL pointer.
    if (str == 0)
        return 0;

    // Process every character in string.
    for (;;)
    {
        // Check numeric.
        if (*str < '0' || *str > '9')
            return 0;

        // Prevent leading zeros.
        if (chcnt > 0 && accum == 0)
            return 0;

        // Accumulate and check segment.
        accum = accum * 10 + *str - '0';
        if (accum > 255)
            return 0;

        // Store result.
        if (segs)
            segs[dots] = (unsigned char)accum;

        // Advance other segment specific stuff.
        ++chcnt;
        ++str;

        // Finish at the end of the string when 3 points are found.
        if (*str == '\0' && dots == 3)
            return 1;

        // Segment changeover.
        if (*str == '.')
        {
            // Limit number of segments.
            ++dots;
            if (dots == 4)
                return 0;

            // Reset segment values.
            chcnt = 0;
            accum = 0;
            ++str;
        }
    }
}