/* Extract X.509 certificate in DER form from PKCS#11 or PEM.
 *
 * Copyright © 2014 Red Hat, Inc. All Rights Reserved.
 * Copyright © 2015 Intel Corporation.
 *
 * Authors: David Howells <dhowells@redhat.com>
 *          David Woodhouse <dwmw2@infradead.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <getopt.h>
#include <err.h>
#include <arpa/inet.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#include <openssl/pem.h>
#include <openssl/pkcs7.h>
#include <openssl/err.h>
#include <openssl/engine.h>

#define PKEY_ID_PKCS7 2

static __attribute__((noreturn))
void format(void)
{
	fprintf(stderr,
		"Usage: scripts/extract-cert <source> <dest>\n");
	exit(2);
}

static void display_openssl_errors(int l)
{
	const char *file;
	char buf[120];
	int e, line;

	if (ERR_peek_error() == 0)
		return;
	fprintf(stderr, "At main.c:%d:\n", l);

	while ((e = ERR_get_error_line(&file, &line))) {
		ERR_error_string(e, buf);
		fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
	}
}

static void drain_openssl_errors(void)
{
	const char *file;
	int line;

	if (ERR_peek_error() == 0)
		return;
	while (ERR_get_error_line(&file, &line)) {}
}

#define ERR(cond, fmt, ...)				\
	do {						\
		bool __cond = (cond);			\
		display_openssl_errors(__LINE__);	\
		if (__cond) {				\
			err(1, fmt, ## __VA_ARGS__);	\
		}					\
	} while(0)

static const char *key_pass;

int main(int argc, char **argv)
{
	char *cert_src, *cert_dst;
	X509 *x509;
	BIO *b;

	OpenSSL_add_all_algorithms();
	ERR_load_crypto_strings();
	ERR_clear_error();

        key_pass = getenv("KBUILD_SIGN_PIN");

	if (argc != 3)
		format();

	cert_src = argv[1];
	cert_dst = argv[2];

	if (!strncmp(cert_src, "pkcs11:", 7)) {
		ENGINE *e;
		struct {
			const char *cert_id;
			X509 *cert;
		} parms;

		parms.cert_id = cert_src;
		parms.cert = NULL;

		ENGINE_load_builtin_engines();
		drain_openssl_errors();
		e = ENGINE_by_id("pkcs11");
		ERR(!e, "Load PKCS#11 ENGINE");
		if (ENGINE_init(e))
			drain_openssl_errors();
		else
			ERR(1, "ENGINE_init");
		if (key_pass)
			ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
		ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1);
		ERR(!parms.cert, "Get X.509 from PKCS#11");
		x509 = parms.cert;
	} else {
		b = BIO_new_file(cert_src, "rb");
		ERR(!b, "%s", cert_src);
		x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
		ERR(!x509, "%s", cert_src);
		BIO_free(b);
	}

	b = BIO_new_file(cert_dst, "wb");
	ERR(!b, "%s", cert_dst);
	ERR(!i2d_X509_bio(b, x509), cert_dst);
	BIO_free(b);

	return 0;
}