On Saturday 2012-09-15 12:58, Aft nix wrote:
>
>struct enc_info {
> __u8 key[XT_OBSF_MAX_KEY_LEN];
> __u8 kl;
> };
>
>struct pad_info {
> __u8 s;
> __u8 e;
> };
Meaningful member names and a description à la kerneldoc would
help here understanding what these are actually for..
(like, which is to be filled with XT_OBSF_ values)
>
>struct xt_OBSF_tginfo {
> __u8 flags;
> struct enc_info *e_info;
> struct xt_obsf_priv *priv;
>};
You must not use pointers in general. When retrieving the ruleset
from the kernel, they will not have any sensible value. While that
is ok for kernel-private fields like "priv" here, it's not for
e_info and p_info which you will likely want to dump in userspace.
>struct xt_OBSF_tginfo_v1 {
> __u8 flags;
> struct enc_info *e_info;
> struct pad_info *p_info;
> struct xt_obsf_priv *priv;
>};
>
>What i'm trying to do is following:
>
>struct xt_OBSF_info * info;
>
>--key "key" will go into info->e_info->key
>--keylen "len" will go into info->e_info->kl
>--enc-type static/random will set flag in info->flags
>
>--pad if its present then struct xt_OBSF_info_v1 will be used.
>--pad-type static/random will set flag into info->flags
>--s "start_value" and --e "end_value" will go info info->p_info->s and
>info->p_info->e
>
>Now i'm confused how i should initialize
>
Barring what I said above about e_info and p_info,
enum {
O_OBSF_KEY,
O_OBSF_KEYLEN,
};
enum { /* only if needed */
F_OBSF_KEY = 1 << O_OBSF_KEY,
...
};
struct xt_option_entry OBSF_opts[] = {
{.name = "key", .id = O_OBSF_KEY, .type = XTTYPE_STRING,
.flags = XTOPT_PUT, XTOPT_POINTER(struct enc_info, key)},
--keylen is redundant, because you can devise that from the key itself
{.name = "enc-type", .id = O_OBSF_ENC_TYPE, .type = XTTYPE_STRING},
XTOPT_TABLEEND,
};
static int parse(struct xt_option_call *cb)
{
struct xt_OBSF_v1 *info = cb->data;
xtables_option_parse(cb);
switch (cb->entry->id) {
case O_OBSF_KEY:
info->e_info->keylen = strlen(info->e_info->key);
break;
case O_OBSF_ENC_TYPE:
if (strcmp(cb->arg, "static") == 0)
info->flags |= ...
else if (strcmp(cb->arg, "random") == 0)
...
break;
...
}
}
>I've seen the example for xt_NFQUEUE.c and tried to model my
>initialization after it, but
>its a little confusing.
The getopt structure facilitates placing the values for certain
options (of certain types, like uint32, etc.) directly into the
info without requiring parse code.
For things like --enc-type which go beyond generic "put a into b"
you need manual code, done in said parse function.
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