Returns the CA type of a pem file

what-ca-are-you.cpp

#include <iostream>
#include <openssl/pem.h>
#include <openssl/x509v3.h>

int main(int argc, char *argv[]) {
  if (argc != 2) {
    std::cout << "usage: ./what-ca-are-you [certificate.crt]" << std::endl;
    return 0;
  }

  FILE *infile = fopen(argv[1], "rb");
  if (!infile) {
    std::cerr << "Unable to open file: " << argv[1] << std::endl;
    return 1;
  }
  X509* cert = PEM_read_X509(infile, NULL, NULL, NULL);
  if (!cert) {
    std::cerr << "Unable to parse certificate: " << argv[1] << std::endl;
  }

  int is_ca = X509_check_ca(cert);
  std::cout << "CA Type: " << is_ca << std::endl;
  return 0;
}