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/*
* Souce: https://bani.com.br/2012/05/programmatically-managing-iptables-rules-in-c-iptc/
*
* changed by silvino at bk dot ru to meet personal taste
* to query https://tldp.org/HOWTO/Querying-libiptc-HOWTO/mfunction.html
*/
#define BUFSIZ 64
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <libiptc/libiptc.h>
struct {
struct ipt_entry entry;
struct xt_standard_target target;
} entry;
//struct xtc_handle *h;
static int insert_rule (
//struct xtc_handle *h,
const char *table,
const char *chain,
unsigned int src,
int inverted_src,
unsigned int dest,
int inverted_dst,
const char *target) {
struct xtc_handle *h;
int ret = 1;
h = iptc_init (table);
if (!h) {
fprintf (stderr, "Could not init IPTC library: %s\n", iptc_strerror (errno));
goto out;
}
entry.entry.ip.src.s_addr = INADDR_ANY;
entry.entry.ip.smsk.s_addr = 0;
entry.entry.ip.dst.s_addr = INADDR_ANY;
entry.entry.ip.dmsk.s_addr = 0;
/* target */
entry.target.target.u.user.target_size = XT_ALIGN (sizeof (struct xt_standard_target));
strncpy (entry.target.target.u.user.name, target, sizeof (entry.target.target.u.user.name));
/* entry */
entry.entry.target_offset = sizeof (struct ipt_entry);
entry.entry.next_offset = entry.entry.target_offset + entry.target.target.u.user.target_size;
if (src) {
entry.entry.ip.src.s_addr = src;
entry.entry.ip.smsk.s_addr = 0xFFFFFFFF;
if (inverted_src)
entry.entry.ip.invflags |= IPT_INV_SRCIP;
}
if (dest) {
entry.entry.ip.dst.s_addr = dest;
entry.entry.ip.dmsk.s_addr = 0xFFFFFFFF;
if (inverted_dst)
entry.entry.ip.invflags |= IPT_INV_DSTIP;
}
if (!iptc_append_entry (chain, (struct ipt_entry *) &entry, h)) {
fprintf (stderr, "Could not insert a rule in iptables (table %s): %s\n", table, iptc_strerror (errno));
return ret;
}
if (!iptc_commit (h)) {
fprintf (stderr, "Could not commit changes in iptables (table %s): %s\n", table, iptc_strerror (errno));
return ret;
}
ret = 0;
out:
if (h)
iptc_free(h);
return ret;
}
void *xrealloc(void *ptr, size_t size) {
ptr = realloc(ptr, size);
if (ptr == NULL && size != 0) {
exit(EXIT_FAILURE);
}
return ptr;
}
char *xstrdup(const char *s) {
char *t;
if (s == NULL)
return NULL;
t = strdup(s);
if (t == NULL) {
exit(EXIT_FAILURE);
}
return t;
}
char *file_read_line_alloc(FILE *fp) {
char buf[BUFSIZ];
unsigned int buf_len;
char *line = NULL;
unsigned int line_size = 0;
int got_nl = 0;
buf[0] = '\0';
while (fgets(buf, BUFSIZ, fp)) {
buf_len = strlen(buf);
if (buf[buf_len - 1] == '\n') {
buf_len--;
buf[buf_len] = '\0';
got_nl = 1;
}
if (line) {
line_size += buf_len;
line = xrealloc(line, line_size + 1);
strncat(line, buf, line_size);
} else {
line_size = buf_len + 1;
line = xstrdup(buf);
}
if (got_nl)
break;
}
return line;
}
int main (int argc, char **argv) {
const char *chain_in="blockip_in";
const char *chain_out="blockip_out";
long int total=0;
if(argc > 1 && strcmp(argv[1], "-h") == 0){
printf("\nip_blocker accepts a list of ip's from a file or stdin\n");
printf("ip's are added to %s and %s chains\n\n", chain_in, chain_out);
printf("ip_blocker [file]\n");
exit(0);
}
unsigned int a, b, ret;
char *line = NULL;
FILE *fp = argc > 1 ? fopen (argv[1], "r") : stdin;
if (!fp) {
fprintf (stderr, "error: file open failed '%s'.\n", argv[1]);
exit(EXIT_FAILURE);
}
memset (&entry, 0, sizeof (entry));
while (line = file_read_line_alloc(fp)) {
inet_pton (AF_INET, line, &a);
ret = insert_rule (
// handler
//h,
//const char *table,
"filter",
//const char *chain,
chain_in,
//unsigned int src,
a,
//int inverted_src,
0,
//unsigned int dest,
NULL,
//int inverted_dst,
0,
//const char *target
"DROP");
if(ret == 1){
printf("Failed to add %s to %s does %s chain exists ?", line, chain_in, chain_in);
free (line);
fclose(fp);
exit(EXIT_FAILURE);
}
ret = insert_rule (
// handler
//h,
//const char *table,
"filter",
//const char *chain,
chain_out,
//unsigned int src,
NULL,
//int inverted_src,
0,
//unsigned int dest,
a,
//int inverted_dst,
0,
//const char *target
"DROP");
if(ret == 1){
printf("Failed to add %s to %s does %s chain exists ?", line, chain_out, chain_out);
free (line);
fclose(fp);
exit(EXIT_FAILURE);
}
total = total + 1;
free (line);
line = NULL;
}
if(fp){
fclose(fp);
}
printf ("total ip's added; %i\n", total);
return 0;
}
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