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138 lines
3.1 KiB
138 lines
3.1 KiB
#include <ctype.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcgios.h>
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#include <fcgi_stdio.h>
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#include <gnutls/gnutls.h>
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#include <gnutls/crypto.h>
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// allow to redefine as gcc -D...
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#ifndef DIR
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#define DIR "/tmp"
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#endif
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#define HTTP_OK 200
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#define HTTP_BAD_REQUEST 400
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#define HTTP_ERROR 500
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/* Here we could verify validity of a IPv4 or IPv6 address,
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* but that is very complex. Just sanitize input. */
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int
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_verify_ip(char *ip){
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int rc = 0;
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for (int i = 0; i < strlen(ip); i++){
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if (!( (ip[i] == '.') || /* IPv4 dots */
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(ip[i] == ':') || /* IPv6 */
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(ip[i] == '/') || /* XXX Is it needed for IPv6? */
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(isalnum(ip[i]) > 0) /* Numbers (v4 and v6) and letters (v6) */
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)) {
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rc = i;
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break;
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}
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}
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return rc;
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}
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/* Generate a random alphanum sequence
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* Example: 10841ee0cc4f (12 chars) */
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int
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_rand(char **rs){
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// https://books.google.ru/books?id=1nG3BwAAQBAJ
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// hex.data will be 6x2=12 chars
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unsigned char buf_rnd[6];
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gnutls_datum_t rnd = { buf_rnd, sizeof(buf_rnd) };
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int rc;
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rc = gnutls_rnd(GNUTLS_RND_NONCE, rnd.data, rnd.size);
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if (rc != GNUTLS_E_SUCCESS) {
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printf("Error in gnutls_rnd()");
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goto out;
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}
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gnutls_datum_t hex;
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rc = gnutls_hex_encode2(&rnd, &hex);
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if (rc != GNUTLS_E_SUCCESS) {
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printf("Error in gnutls_hex_encode2()");
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goto out;
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}
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*rs = malloc(hex.size);
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rc = sprintf(*rs, "%s", hex.data);
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if (rc < 0) {
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printf("Error in sprintf()");
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goto out;
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}
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out:
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return rc;
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}
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int
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main(){
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int rc = 0;
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int http_code = HTTP_ERROR;
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if (access(DIR, W_OK) != 0) {
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fprintf(stderr, "Directory %s does not exist or is not writable\n", DIR);
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goto out;
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}
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// first chdir() and then chroot()!
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if (!( chdir(DIR) == 0 && chroot(DIR) == 0 )) {
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fprintf(stderr, "Cannot chdir and chroot into %s\n", DIR);
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goto out;
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}
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while(FCGI_Accept() >= 0) {
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char *ip = getenv("REMOTE_ADDR");
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if (ip == NULL) {
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fprintf(stderr, "%s\n", "Env REMOTE_ADDR is not set");
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http_code = HTTP_ERROR;
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goto fcgi_out;
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}
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rc = _verify_ip(ip);
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if (rc != 0) {
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fprintf(stderr, "%s\n", "Incorrect REMOTE_ADDR");
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http_code = HTTP_BAD_REQUEST;
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goto fcgi_out;
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}
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char *hex;
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int max_try = 10;
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for (int i = 1; i <= max_try; i++) {
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if (i == max_try) {
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fprintf(stderr, "%s\n", "Error in random file loop");
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http_code = HTTP_ERROR;
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goto fcgi_out;
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}
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rc = _rand(&hex);
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if (rc < 0) {
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fprintf(stderr, "Error in _rand()");
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continue;
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}
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if (access(hex, F_OK) != 0) {
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break;
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}
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}
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FCGI_FILE *d = fopen(hex, "w");
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if (d == NULL) {
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fprintf(stderr, "Error openning file %s/%s for writing\n", DIR, hex);
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http_code = HTTP_ERROR;
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goto fcgi_out;
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}
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fprintf(d, "%s", ip);
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rc = fclose(d);
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if (rc != 0) {
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fprintf(stderr, "Error closing file %s/%s\n", DIR, hex);
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http_code = HTTP_ERROR;
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goto fcgi_out;
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}
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http_code = HTTP_OK;
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fcgi_out:
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printf("Status: %d\n", http_code);
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printf("Content-Type: text/plain; charset=utf-8\n");
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if (http_code == HTTP_OK) {
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printf("%s\n", "OK");
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rc = 0;
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} else {
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rc = 1;
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}
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}
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out:
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return rc;
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}
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