/**
 * A simple program that loads certificate and dumps it to the
 * stdout.
 *
 * Written by Stjepan Gros <stjepan.gros@gmail.com>. Use this
 * code as it suites you.
 */
#include <stdio.h>

#include <gnutls/gnutls.h>
#include <gnutls/x509.h>

#include <glib.h>

gnutls_datum_t *load_file(const char *file)
{
	FILE *f;
	size_t filelen, size;
	void *ptr = NULL;
	gnutls_datum_t *loaded_file = NULL;

	if ((f = fopen(file, "r")) != NULL) {

		if (fseek(f, 0, SEEK_END) != 0) {
			perror("fseek");
			goto out;
		}

		if ((filelen = ftell(f)) < 0) {
			perror("ftell");
			goto out;
		}

		if (fseek(f, 0, SEEK_SET) != 0) {
			perror("fseek");
			goto out;
		}

		ptr = g_malloc(filelen);

		if ((size = fread(ptr, 1, filelen, f)) < filelen) {
			if (size < 0)
				perror("fread");

			goto out;
		}

		loaded_file = g_malloc0(sizeof(gnutls_datum_t));

		loaded_file->data = ptr;
		loaded_file->size = filelen;

out:
		fclose(f);
	} else
		perror ("fopen");

	return loaded_file;
}

void unload_file(gnutls_datum_t *file)
{
	g_free(file->data);
	g_free(file);
}

int main(int argc, char **argv)
{
	gnutls_x509_crt_t crt;
	gnutls_datum_t *crt_file = NULL;
	int ret;
	gnutls_datum_t txt_cert;

	if (argc != 2) {
		fprintf (stderr, "Usage: %s <certificate>\n", argv[0]);
		return 1;
	}

	if ((crt_file = load_file(argv[1])) == NULL)
		return 1;

	gnutls_global_init();

	gnutls_x509_crt_init(&crt);

	ret = gnutls_x509_crt_import(crt, crt_file, GNUTLS_X509_FMT_PEM);
	unload_file(crt_file);

	if (ret < 0) {
		fprintf(stderr, "Error: %s\n", gnutls_strerror(ret));
		return 1;
	}

	gnutls_x509_crt_print(crt, GNUTLS_CRT_PRINT_FULL, &txt_cert);

	gnutls_x509_crt_deinit(crt);

	printf("%s\n", txt_cert.data);

	return 0;
}