Re: Secure coding in C (was Re: Administrivia #4883)

[crowland () CISCO COM (Craig H. Rowland)]

> Brian Masney wrote:
> > > ]     char *a = something();
> > > ]     char *b = something_else();
> > > ]     int len = strlen(a) + strlen(b);
> > > ]     char *c = malloc(len + 1) || die("malloc");
> > > ]     (void) strcat(strcpy(c, a), b);
>
> I'm partial to strncpy(); strcpy is a known hobgoblin to secure
programming.

strncpy() has its problems too (i.e. it doesn't null terminate if the src is
too long). I wrote my own SafeStrncpy() function but I think a better choice
is the strlcpy() and strlcat() functions that come with OpenBSD. Theo
DeRaadt has a presentation on this as well. You should search the OpenBSD
site and source tree for more information. The strlcpy() and strlcat()
functions take care of a lot of nonsense present in the default C string
handling libraries.

-- Craig