98 lines
2.3 KiB
C
98 lines
2.3 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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// nft46 'add element inet reaction ipvXbans { 1.2.3.4 }' → nft 'add element inet reaction ipv4bans { 1.2.3.4 }'
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// nft46 'add element inet reaction ipvXbans { a:b::c:d }' → nft 'add element inet reaction ipv6bans { a:b::c:d }'
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//
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// the character X is replaced by 4 or 6 depending on the address family of the specified IP
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//
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// Limitations:
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// - nft46 must receive exactly one argument
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// - only one IP must be given per command
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// - the IP must be between { braces }
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int isIPv4(char *tab, int len) {
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int i;
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// IPv4 addresses are at least 7 chars long
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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, int len) {
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int i;
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// IPv6 addresses are at least 3 chars long
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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 findchar(char *tab, char c, int i, int len) {
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while (i < len && tab[i] != c) i++;
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if (i == len) {
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printf("nft46: one %c must be present", c);
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exit(1);
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}
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return i;
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}
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void adapt_args(char *tab) {
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int i, len, X, startIP, endIP, startedIP;
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X = startIP = endIP = -1;
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startedIP = 0;
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len = strlen(tab);
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i = 0;
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X = i = findchar(tab, 'X', i, len);
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startIP = i = findchar(tab, '{', i, len);
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while (startIP + 1 <= (i = findchar(tab, ' ', i, len))) startIP = i + 1;
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i = startIP;
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endIP = i = findchar(tab, ' ', i, len) - 1;
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if (isIPv4(tab+startIP, endIP-startIP+1)) {
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tab[X] = '4';
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return;
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}
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if (isIPv6(tab+startIP, endIP-startIP+1)) {
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tab[X] = '6';
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return;
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}
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printf("nft46: no IP address found\n");
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exit(1);
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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("nft46: 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("nft46: Exactly one argument must be given\n");
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exit(1);
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}
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adapt_args(argv[1]);
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exec("nft", argv);
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}
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