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#include <errno.h>
#include <stdbool.h>
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <xtables.h>
#include <linux/netfilter/xt_connlabel.h>
enum {
O_LABEL = 0,
O_SET = 1,
};
#define CONNLABEL_CFG "/etc/xtables/connlabel.conf"
static void connlabel_mt_help(void)
{
puts(
"connlabel match options:\n"
"[!] --label name Match if label has been set on connection\n"
" --set Set label on connection");
}
static const struct xt_option_entry connlabel_mt_opts[] = {
{.name = "label", .id = O_LABEL, .type = XTTYPE_STRING,
.min = 1, .flags = XTOPT_MAND|XTOPT_INVERT},
{.name = "set", .id = O_SET, .type = XTTYPE_NONE},
XTOPT_TABLEEND,
};
static int
xtables_parse_connlabel_numerical(const char *s, char **end)
{
uintmax_t value;
if (!xtables_strtoul(s, end, &value, 0, XT_CONNLABEL_MAXBIT))
return -1;
return value;
}
static bool is_space_posix(int c)
{
return c == ' ' || c == '\f' || c == '\r' || c == '\t' || c == '\v';
}
static char * trim_label(char *label)
{
char *end;
while (is_space_posix(*label))
label++;
end = strchr(label, '\n');
if (end)
*end = 0;
else
end = strchr(label, '\0');
end--;
while (is_space_posix(*end) && end > label) {
*end = 0;
end--;
}
return *label ? label : NULL;
}
static void
xtables_get_connlabel(uint16_t bit, char *buf, size_t len)
{
FILE *fp = fopen(CONNLABEL_CFG, "r");
char label[1024];
char *end;
if (!fp)
goto error;
while (fgets(label, sizeof(label), fp)) {
int tmp;
if (label[0] == '#')
continue;
tmp = xtables_parse_connlabel_numerical(label, &end);
if (tmp < 0 || tmp < (int) bit)
continue;
if (tmp > (int) bit)
break;
end = trim_label(end);
if (!end)
continue;
snprintf(buf, len, "%s", end);
fclose(fp);
return;
}
fclose(fp);
error:
snprintf(buf, len, "%u", (unsigned int) bit);
}
static uint16_t xtables_parse_connlabel(const char *s)
{
FILE *fp = fopen(CONNLABEL_CFG, "r");
char label[1024];
char *end;
int bit;
if (!fp)
xtables_error(PARAMETER_PROBLEM, "label '%s': could not open '%s': %s",
s, CONNLABEL_CFG, strerror(errno));
while (fgets(label, sizeof(label), fp)) {
if (label[0] == '#' || !strstr(label, s))
continue;
bit = xtables_parse_connlabel_numerical(label, &end);
if (bit < 0)
continue;
end = trim_label(end);
if (!end)
continue;
if (strcmp(end, s) == 0) {
fclose(fp);
return bit;
}
}
fclose(fp);
xtables_error(PARAMETER_PROBLEM, "label '%s' not found in config file %s",
s, CONNLABEL_CFG);
}
static void connlabel_mt_parse(struct xt_option_call *cb)
{
struct xt_connlabel_mtinfo *info = cb->data;
int tmp;
xtables_option_parse(cb);
switch (cb->entry->id) {
case O_LABEL:
tmp = xtables_parse_connlabel_numerical(cb->arg, NULL);
info->bit = tmp < 0 ? xtables_parse_connlabel(cb->arg) : tmp;
if (cb->invert)
info->options |= XT_CONNLABEL_OP_INVERT;
break;
case O_SET:
info->options |= XT_CONNLABEL_OP_SET;
break;
}
}
static void
connlabel_mt_print_op(const struct xt_connlabel_mtinfo *info, const char *prefix)
{
if (info->options & XT_CONNLABEL_OP_SET)
printf(" %sset", prefix);
}
static void
connlabel_mt_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
const struct xt_connlabel_mtinfo *info = (const void *)match->data;
char buf[1024];
printf(" connlabel");
if (info->options & XT_CONNLABEL_OP_INVERT)
printf(" !");
if (numeric) {
printf(" %u", info->bit);
} else {
xtables_get_connlabel(info->bit, buf, sizeof(buf));
printf(" '%s'", buf);
}
connlabel_mt_print_op(info, "");
}
static void
connlabel_mt_save(const void *ip, const struct xt_entry_match *match)
{
const struct xt_connlabel_mtinfo *info = (const void *)match->data;
char buf[1024];
if (info->options & XT_CONNLABEL_OP_INVERT)
printf(" !");
xtables_get_connlabel(info->bit, buf, sizeof(buf));
printf(" --label \"%s\"", buf);
connlabel_mt_print_op(info, "--");
}
static struct xtables_match connlabel_mt_reg = {
.family = NFPROTO_UNSPEC,
.name = "connlabel",
.version = XTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_connlabel_mtinfo)),
.userspacesize = offsetof(struct xt_connlabel_mtinfo, bit),
.help = connlabel_mt_help,
.print = connlabel_mt_print,
.save = connlabel_mt_save,
.x6_parse = connlabel_mt_parse,
.x6_options = connlabel_mt_opts,
};
void _init(void)
{
xtables_register_match(&connlabel_mt_reg);
}
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