About the UNIX socket path length check

[Ruslan Ermilov]

On Thu, Oct 09, 2014 at 06:02:16PM +0200, Peter Wu wrote:
> Hi,
> 
> In src/core/ngx_inet.c we have this code:
> 
>     if (len > sizeof(saun->sun_path)) {
>         u->err = "too long path in the unix domain socket";
>         return NGX_ERROR;
>     }
> 
> But a NUL-terminated string requires one byte more. Is it allowed to
> omit the NUL byte when the string would not fit otherwise? If not,
> this should be changed to:
> 
>     if (len >= sizeof(saun->sun_path)) {
>         u->err = "too long path in the unix domain socket";
>         return NGX_ERROR;
>     }

The "len" you quote includes the slot for NUL due to

	u->host.len = len++;

And ngx_strncpy() always NULL-terminates what it writes.