/* 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>
  #include <openssl/engine.h>
  
  #define PKEY_ID_PKCS7 2
  
  static __attribute__((noreturn))
  void format(void)
  {
  	fprintf(stderr,
  		"Usage: scripts/extract-cert <source> <dest>
  ");
  	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:
  ", l);
  
  	while ((e = ERR_get_error_line(&file, &line))) {
  		ERR_error_string(e, buf);
  		fprintf(stderr, "- SSL %s: %s:%d
  ", 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;

  static BIO *wb;
  static char *cert_dst;
  int kbuild_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 (kbuild_verbose)
  		fprintf(stderr, "Extracted cert: %s
  ", buf);
  }

  
  int main(int argc, char **argv)
  {

  	char *cert_src;

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

  	kbuild_verbose = atoi(getenv("KBUILD_VERBOSE")?:"0");

          key_pass = getenv("KBUILD_SIGN_PIN");
  
  	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)) {

  		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");

  		write_cert(parms.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;
  }