/* Extract X.509 certificate in DER form from PKCS#11 or PEM.
 *
 * Copyright © 2014-2015 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 Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * 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 <err.h>
#include <openssl/bio.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#if OPENSSL_VERSION_MAJOR >= 3
# define USE_PKCS11_PROVIDER
# include <openssl/provider.h>
# include <openssl/store.h>
#else
# if !defined(OPENSSL_NO_ENGINE) && !defined(OPENSSL_NO_DEPRECATED_3_0)
#  define USE_PKCS11_ENGINE
#  include <openssl/engine.h>
# endif
#endif
#include "ssl-common.h"

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

#ifdef USE_PKCS11_ENGINE
static const char *key_pass;
#endif
static BIO *wb;
static char *cert_dst;
static bool verbose;

static void write_cert(X509 *x509)
{
	char buf[200];

	if (!wb) {
		wb = BIO_new_file(cert_dst, "wb");
		ERR(!wb, "%s", cert_dst);
	}
	X509_NAME_oneline(X509_get_subject_name(x509), buf, sizeof(buf));
	ERR(!i2d_X509_bio(wb, x509), "%s", cert_dst);
	if (verbose)
		fprintf(stderr, "Extracted cert: %s\n", buf);
}

static X509 *load_cert_pkcs11(const char *cert_src)
{
	X509 *cert = NULL;
#ifdef USE_PKCS11_PROVIDER
	OSSL_STORE_CTX *store;

	if (!OSSL_PROVIDER_try_load(NULL, "pkcs11", true))
		ERR(1, "OSSL_PROVIDER_try_load(pkcs11)");
	if (!OSSL_PROVIDER_try_load(NULL, "default", true))
		ERR(1, "OSSL_PROVIDER_try_load(default)");

	store = OSSL_STORE_open(cert_src, NULL, NULL, NULL, NULL);
	ERR(!store, "OSSL_STORE_open");

	while (!OSSL_STORE_eof(store)) {
		OSSL_STORE_INFO *info = OSSL_STORE_load(store);

		if (!info) {
			drain_openssl_errors(__LINE__, 0);
			continue;
		}
		if (OSSL_STORE_INFO_get_type(info) == OSSL_STORE_INFO_CERT) {
			cert = OSSL_STORE_INFO_get1_CERT(info);
			ERR(!cert, "OSSL_STORE_INFO_get1_CERT");
		}
		OSSL_STORE_INFO_free(info);
		if (cert)
			break;
	}
	OSSL_STORE_close(store);
#elif defined(USE_PKCS11_ENGINE)
		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(__LINE__, 1);
		e = ENGINE_by_id("pkcs11");
		ERR(!e, "Load PKCS#11 ENGINE");
		if (ENGINE_init(e))
			drain_openssl_errors(__LINE__, 1);
		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");
		cert = parms.cert;
#else
		fprintf(stderr, "no pkcs11 engine/provider available\n");
		exit(1);
#endif
	return cert;
}

int main(int argc, char **argv)
{
	char *cert_src;
	char *verbose_env;

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

	verbose_env = getenv("KBUILD_VERBOSE");
	if (verbose_env && strchr(verbose_env, '1'))
		verbose = true;

#ifdef USE_PKCS11_ENGINE
	key_pass = getenv("KBUILD_SIGN_PIN");
#endif

	if (argc != 3)
		format();

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

	if (!cert_src[0]) {
		/* Invoked with no input; create empty file */
		FILE *f = fopen(cert_dst, "wb");
		ERR(!f, "%s", cert_dst);
		fclose(f);
		exit(0);
	} else if (!strncmp(cert_src, "pkcs11:", 7)) {
		X509 *cert = load_cert_pkcs11(cert_src);

		ERR(!cert, "load_cert_pkcs11 failed");
		write_cert(cert);
	} else {
		BIO *b;
		X509 *x509;

		b = BIO_new_file(cert_src, "rb");
		ERR(!b, "%s", cert_src);

		while (1) {
			x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
			if (wb && !x509) {
				unsigned long err = ERR_peek_last_error();
				if (ERR_GET_LIB(err) == ERR_LIB_PEM &&
				    ERR_GET_REASON(err) == PEM_R_NO_START_LINE) {
					ERR_clear_error();
					break;
				}
			}
			ERR(!x509, "%s", cert_src);
			write_cert(x509);
		}
	}

	BIO_free(wb);

	return 0;
}