#include <stdio.h>
#include <stdlib.h>

int main(void) {
  /* const char *remote_addr = getenv("REMOTE_ADDR"); */
  const char *remote_addr = getenv("HTTP_X_FORWARDED_FOR");
  if (remote_addr == NULL) {
    remote_addr = "(null)";
  }

  printf("Content-Type: text/plain\n");
  printf("\n");

  printf("%s\n", remote_addr);

  return 0;
}