92 lines
2.0 KiB
C
92 lines
2.0 KiB
C
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#include<ctype.h>
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#include<errno.h>
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#include<stdio.h>
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#include<stdlib.h>
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#include<string.h>
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#include<unistd.h>
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// If this programs
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// - receives an ipv4 address in its arguments:
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// → it will executes iptables with the same arguments in place.
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//
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// - receives an ipv6 address in its arguments:
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// → it will executes ip6tables with the same arguments in place.
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//
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// - doesn't receive an ipv4 or ipv6 address in its arguments:
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// → it will executes both, with the same arguments in place.
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int isIPv4(char *tab) {
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int i,len;
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// IPv4 addresses are at least 7 chars long
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len = strlen(tab);
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if (len < 7 || !isdigit(tab[0]) || !isdigit(tab[len-1])) {
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return 0;
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}
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// Each char must be a digit or a dot between 2 digits
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for (i=1; i<len-1; i++) {
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if (!isdigit(tab[i]) && !(tab[i] == '.' && isdigit(tab[i-1]) && isdigit(tab[i+1]))) {
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return 0;
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}
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}
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return 1;
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}
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int isIPv6(char *tab) {
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int i,len, twodots = 0;
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// IPv6 addresses are at least 3 chars long
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len = strlen(tab);
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if (len < 3) {
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return 0;
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}
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// Each char must be a digit, :, a-f, or A-F
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for (i=0; i<len; i++) {
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if (!isdigit(tab[i]) && tab[i] != ':' && !(tab[i] >= 'a' && tab[i] <= 'f') && !(tab[i] >= 'A' && tab[i] <= 'F')) {
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return 0;
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}
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}
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return 1;
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}
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int guess_type(int len, char *tab[]) {
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int i;
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for (i=0; i<len; i++) {
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if (isIPv4(tab[i])) {
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return 4;
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} else if (isIPv6(tab[i])) {
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return 6;
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}
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}
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return 0;
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}
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int exec(char *str, char **argv) {
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argv[0] = str;
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execvp(str, argv);
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// returns only if fails
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printf("ip46tables: exec failed %d\n", errno);
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}
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int main(int argc, char **argv) {
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if (argc < 2) {
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printf("ip46tables: At least one argument has to be given\n");
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exit(1);
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}
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int type;
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type = guess_type(argc, argv);
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if (type == 4) {
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exec("iptables", argv);
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} else if (type == 6) {
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exec("ip6tables", argv);
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} else {
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pid_t pid = fork();
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if (pid == -1) {
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printf("ip46tables: fork failed\n");
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exit(1);
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} else if (pid) {
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exec("iptables", argv);
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} else {
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exec("ip6tables", argv);
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}
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}
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}
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