/* pkcs1-conv.c

   Converting pkcs#1 and related keys to sexp format.

   Copyright (C) 2005, 2009 Niels Möller, Magnus Holmgren
   Copyright (C) 2014 Niels Möller

   This file is part of GNU Nettle.

   GNU Nettle is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.

   GNU Nettle is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see http://www.gnu.org/licenses/.
*/

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "asn1.h"
#include "base64.h"
#include "buffer.h"
#include "rsa.h"
#include "dsa.h"

#include "getopt.h"
#include "misc.h"

enum object_type
  {
    /* Use a range of values which also work as option id:s */
    RSA_PRIVATE_KEY = 0x200,
    RSA_PUBLIC_KEY,
    DSA_PRIVATE_KEY,
    /* DSA public keys only supported as part of a
       SubjectPublicKeyInfo, i.e., the GENERAL_PUBLIC_KEY case. */
    GENERAL_PUBLIC_KEY,
  };

static int
write_file(struct nettle_buffer *buffer, FILE *f)
{
  size_t res = fwrite(buffer->contents, 1, buffer->size, f);
  if (res < buffer->size)
    {
      werror("Write failed: %s.\n", strerror(errno));
      return 0;
    }
  else
    return 1;
}

/* Return 1 on success, 0 on error, -1 on eof */
static int
read_line(struct nettle_buffer *buffer, FILE *f)
{
  int c;
  
  while ((c = getc(f)) != EOF)
    {
      if (!NETTLE_BUFFER_PUTC(buffer, c))
	return 0;

      if (c == '\n')
	return 1;
    }
  if (ferror(f))
    {
      werror("Read failed: %s\n", strerror(errno));
      return 0;
    }
  
  else 
    return -1;
}

static int
read_file(struct nettle_buffer *buffer, FILE *f)
{
  int c;
  
  while ((c = getc(f)) != EOF)
    if (!NETTLE_BUFFER_PUTC(buffer, c))
      return 0;

  if (ferror(f))
    {
      werror("Read failed: %s\n", strerror(errno));
      return 0;
    }
  else
    return 1;
}

static const uint8_t
pem_start_pattern[11] = "-----BEGIN ";

static const uint8_t
pem_end_pattern[9] = "-----END ";

static const uint8_t
pem_trailer_pattern[5] = "-----";

static const char
pem_ws[33] = {
  0, 0, 0, 0, 0, 0, 0, 0,
  0, 1, 1, 1, 1, 1, 0, 0, /* \t, \n, \v, \f, \r */
  0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0,
  1 /* SPC */
};

#define PEM_IS_SPACE(c) ((c) < sizeof(pem_ws) && pem_ws[(c)]) 

/* Returns 1 on match, otherwise 0. */ 
static int
match_pem_start(size_t length, const uint8_t *line,
		size_t *marker_start,
		size_t *marker_length)
{
  while (length > 0 && PEM_IS_SPACE(line[length - 1]))
    length--;

  if (length > (sizeof(pem_start_pattern) + sizeof(pem_trailer_pattern))
      && memcmp(line, pem_start_pattern, sizeof(pem_start_pattern)) == 0
      && memcmp(line + length - sizeof(pem_trailer_pattern),
		pem_trailer_pattern, sizeof(pem_trailer_pattern)) == 0)
    {
      *marker_start = 11;
      *marker_length = length - (sizeof(pem_start_pattern) + sizeof(pem_trailer_pattern));

      return 1;
    }
  else
    return 0;
}

/* Returns 1 on match, -1 if the line is of the right form except for
   the marker, otherwise 0. */ 
static int
match_pem_end(size_t length, const uint8_t *line,
	      size_t marker_length,
	      const uint8_t *marker)
{
  while (length > 0 && PEM_IS_SPACE(line[length - 1]))
    length--;

  if (length > (sizeof(pem_end_pattern) + sizeof(pem_trailer_pattern))
      && memcmp(line, pem_end_pattern, sizeof(pem_end_pattern)) == 0
      && memcmp(line + length - sizeof(pem_trailer_pattern),
		pem_trailer_pattern, sizeof(pem_trailer_pattern)) == 0)
    {
      /* Right form. Check marker */
      if (length == marker_length + (sizeof(pem_end_pattern) + sizeof(pem_trailer_pattern))
	  && memcmp(line + sizeof(pem_end_pattern), marker, marker_length) == 0)
	return 1;
      else
	return -1;
    }
  else
    return 0;  
}

struct pem_info
{
  /* The FOO part in "-----BEGIN FOO-----" */
  size_t marker_start;
  size_t marker_length;
  size_t data_start;
  size_t data_length;
};

static int
read_pem(struct nettle_buffer *buffer, FILE *f,
	 struct pem_info *info)
{  
  /* Find start line */
  for (;;)
    {
      int res;

      nettle_buffer_reset(buffer);

      res = read_line(buffer, f);
      if (res != 1)
	return res;

      if (match_pem_start(buffer->size, buffer->contents,
			  &info->marker_start, &info->marker_length))
	break;
    }

  /* NUL-terminate the marker. Don't care to check for embedded NULs. */
  buffer->contents[info->marker_start + info->marker_length] = 0;

  info->data_start = buffer->size;

  for (;;)
    {
      size_t line_start = buffer->size;

      if (read_line(buffer, f) != 1)
	return 0;

      switch (match_pem_end(buffer->size - line_start,
			    buffer->contents + line_start,
			    info->marker_length,
			    buffer->contents + info->marker_start))
	{
	case 0:
	  break;
	case -1:
	  werror("PEM END line doesn't match BEGIN.\n");
	  return 0;
	case 1:
	  /* Return base 64 data; let caller do the decoding */ 
	  info->data_length = line_start - info->data_start;
	  return 1;
	}
    }
}

static inline int
base64_decode_in_place (struct base64_decode_ctx *ctx, size_t *dst_length,
			size_t length, uint8_t *data)
{
  return base64_decode_update (ctx, dst_length,
			       data, length, (const char *) data);
}

static int
decode_base64(struct nettle_buffer *buffer,
	      size_t start, size_t *length)
{
  struct base64_decode_ctx ctx;
  
  base64_decode_init(&ctx);

  /* Decode in place */
  if (base64_decode_in_place(&ctx, length,
			     *length, buffer->contents + start)
      && base64_decode_final(&ctx))
    return 1;
  
  else
    {
      werror("Invalid base64 date.\n");
      return 0;
    }
}

static int
convert_rsa_public_key(struct nettle_buffer *buffer, size_t length, const uint8_t *data)
{
  struct rsa_public_key pub;
  int res;
  
  rsa_public_key_init(&pub);

  if (rsa_keypair_from_der(&pub, NULL, 0,
			   length, data))
    {
      /* Reuses the buffer */
      nettle_buffer_reset(buffer);
      res = rsa_keypair_to_sexp(buffer, NULL, &pub, NULL);
    }
  else
    {
      werror("Invalid PKCS#1 public key.\n");
      res = 0;
    }
  rsa_public_key_clear(&pub);
  return res;
}

static int
convert_rsa_private_key(struct nettle_buffer *buffer, size_t length, const uint8_t *data)
{
  struct rsa_public_key pub;
  struct rsa_private_key priv;
  int res;
  
  rsa_public_key_init(&pub);
  rsa_private_key_init(&priv);

  if (rsa_keypair_from_der(&pub, &priv, 0,
			   length, data))
    {
      /* Reuses the buffer */
      nettle_buffer_reset(buffer);
      res = rsa_keypair_to_sexp(buffer, NULL, &pub, &priv);
    }
  else
    {
      werror("Invalid PKCS#1 private key.\n");
      res = 0;
    }
  rsa_public_key_clear(&pub);
  rsa_private_key_clear(&priv);

  return res;
}

static int
convert_dsa_private_key(struct nettle_buffer *buffer, size_t length, const uint8_t *data)
{
  struct dsa_params params;
  mpz_t pub;
  mpz_t priv;
  int res;

  dsa_params_init (&params);
  mpz_init (pub);
  mpz_init (priv);

  if (dsa_openssl_private_key_from_der(&params, pub, priv, 0,
				       length, data))
    {
      /* Reuses the buffer */
      nettle_buffer_reset(buffer);
      res = dsa_keypair_to_sexp(buffer, NULL, &params, pub, priv);
    }
  else
    {
      werror("Invalid OpenSSL private key.\n");
      res = 0;
    }
  dsa_params_clear (&params);
  mpz_clear (pub);
  mpz_clear (priv);

  return res;
}

/* Returns 1 on success, 0 on error, and -1 for unsupported algorithms. */
static int
convert_public_key(struct nettle_buffer *buffer, size_t length, const uint8_t *data)
{
  /* SubjectPublicKeyInfo ::= SEQUENCE {
         algorithm		AlgorithmIdentifier,
	 subjectPublicKey 	BIT STRING
     }

     AlgorithmIdentifier ::= SEQUENCE {
         algorithm  	OBJECT IDENTIFIER,
	 parameters 	OPTIONAL
     }
  */
  struct asn1_der_iterator i;
  struct asn1_der_iterator j;
  int res = 0;

  if (asn1_der_iterator_first(&i, length, data) == ASN1_ITERATOR_CONSTRUCTED
      && i.type == ASN1_SEQUENCE
      && asn1_der_decode_constructed_last(&i) == ASN1_ITERATOR_CONSTRUCTED
      && i.type == ASN1_SEQUENCE

      /* Use the j iterator to parse the algorithm identifier */
      && asn1_der_decode_constructed(&i, &j) == ASN1_ITERATOR_PRIMITIVE
      && j.type == ASN1_IDENTIFIER
      && asn1_der_iterator_next(&i) == ASN1_ITERATOR_PRIMITIVE
      && i.type == ASN1_BITSTRING

      /* Use i to parse the object wrapped in the bit string.*/
      && asn1_der_decode_bitstring_last(&i))
    {
      /* pkcs-1 {
	     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1)
	     modules(0) pkcs-1(1)
	 }

	 --
	 -- When rsaEncryption is used in an AlgorithmIdentifier the
	 -- parameters MUST be present and MUST be NULL.
	 --
	 rsaEncryption    OBJECT IDENTIFIER ::= { pkcs-1 1 }
      */
      static const uint8_t id_rsaEncryption[9] =
	{ 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01 };
      /*
	 --
	 -- When dsa is used in an AlgorithmIdentifier the
	 -- parameters MUST be present and MUST NOT be NULL.
	 --
	 dsa    OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) x9-57(10040) x9algorithm(4) 1 }
      */
      static const uint8_t id_dsa[7] =
	{ 0x2A, 0x86, 0x48, 0xCE, 0x38, 0x04, 0x01 };

      switch (j.length)
	{
	unknown:
	default:
	  werror("SubjectPublicKeyInfo: Unsupported algorithm.\n");
	  res = -1;
	  break;
	  
	case 7:
	  if (memcmp(j.data, id_dsa, 7) == 0)
	    {
	      if (asn1_der_iterator_next(&j) == ASN1_ITERATOR_CONSTRUCTED
		  && asn1_der_decode_constructed_last(&j) == ASN1_ITERATOR_PRIMITIVE)
		{
		  struct dsa_params params;
		  mpz_t pub;

		  dsa_params_init (&params);
		  mpz_init (pub);

		  if (dsa_params_from_der_iterator(&params, 0, 0, &i)
		      && dsa_public_key_from_der_iterator(&params, pub, &j))
		    {
		      nettle_buffer_reset(buffer);
		      res = dsa_keypair_to_sexp(buffer, NULL,
						&params, pub, NULL) > 0;
		    }
		  dsa_params_clear(&params);
		  mpz_clear(pub);
		}
	      if (!res)
		werror("SubjectPublicKeyInfo: Invalid DSA key.\n");
	      break;
	    }
	  else goto unknown;
	case 9:
	  if (memcmp(j.data, id_rsaEncryption, 9) == 0)
	    {
	      if (asn1_der_iterator_next(&j) == ASN1_ITERATOR_PRIMITIVE
		  && j.type == ASN1_NULL
		  && j.length == 0
		  && asn1_der_iterator_next(&j) == ASN1_ITERATOR_END)
		{
		  struct rsa_public_key pub;

		  rsa_public_key_init(&pub);

		  if (rsa_public_key_from_der_iterator(&pub, 0, &i))
		    {
		      nettle_buffer_reset(buffer);
		      res = rsa_keypair_to_sexp(buffer, NULL, &pub, NULL) > 0;
		    }
		  rsa_public_key_clear(&pub);
		}
	      if (!res)
		werror("SubjectPublicKeyInfo: Invalid RSA key.\n");
	      break;
	    }
	  else goto unknown;
	}
    }
  else
    werror("SubjectPublicKeyInfo: Invalid object.\n");

  return res;
}

/* NOTE: Destroys contents of buffer */
/* Returns 1 on success, 0 on error, and -1 for unsupported algorithms. */
static int
convert_type(struct nettle_buffer *buffer,
	     enum object_type type,
	     size_t length, const uint8_t *data)
{
  int res;
  
  switch(type)
    {
    default:
      abort();

    case GENERAL_PUBLIC_KEY:
      res = convert_public_key(buffer, length, data);
      break;

    case RSA_PUBLIC_KEY:
      res = convert_rsa_public_key(buffer, length, data);
      break;

    case RSA_PRIVATE_KEY:
      res = convert_rsa_private_key(buffer, length, data);
      break;

    case DSA_PRIVATE_KEY:
      res = convert_dsa_private_key(buffer, length, data);
      break;
    }

  if (res > 0)
    res = write_file(buffer, stdout);

  return res;
}

static int
convert_file(struct nettle_buffer *buffer,
	     FILE *f,
	     enum object_type type,
	     int base64)
{
  if (type)
    {
      read_file(buffer, f);
      if (base64 && !decode_base64(buffer, 0, &buffer->size))
	return 0;
      
      if (convert_type(buffer, type,
		       buffer->size, buffer->contents) != 1)
	return 0;

      return 1;
    }
  else
    {
      /* PEM processing */
      for (;;)
	{
	  struct pem_info info;
	  const uint8_t *marker;
	  
	  nettle_buffer_reset(buffer);
	  switch (read_pem(buffer, f, &info))
	    {
	    default:
	      return 0;
	    case 1:
	      break;
	    case -1:
	      /* EOF */
	      return 1;
	    }

	  if (!decode_base64(buffer, info.data_start, &info.data_length))
	    return 0;

	  marker = buffer->contents + info.marker_start;

	  type = 0;
	  switch (info.marker_length)
	    {
	    case 10:
	      if (memcmp(marker, "PUBLIC KEY", 10) == 0)
		type = GENERAL_PUBLIC_KEY;
	      break;

	    case 14:
	      if (memcmp(marker, "RSA PUBLIC KEY", 14) == 0)
		type = RSA_PUBLIC_KEY;
	      break;

	    case 15:
	      if (memcmp(marker, "RSA PRIVATE KEY", 15) == 0)
		type = RSA_PRIVATE_KEY;
	      else if (memcmp(marker, "DSA PRIVATE KEY", 15) == 0)
		type = DSA_PRIVATE_KEY;
	      break;
	    }
	  
	  if (!type)
	    werror("Ignoring unsupported object type `%s'.\n", marker);

	  else if (convert_type(buffer, type,
				info.data_length,
				buffer->contents + info.data_start) != 1)
	    return 0;
	}
    }
}

int
main(int argc, char **argv)
{
  struct nettle_buffer buffer;
  enum object_type type = 0;
  int base64 = 0;
  int c;

  enum {
    OPT_HELP = 0x300,
    OPT_PRIVATE_RSA = RSA_PRIVATE_KEY,
    OPT_PUBLIC_RSA = RSA_PUBLIC_KEY,
    OPT_PRIVATE_DSA = DSA_PRIVATE_KEY,
    OPT_PUBLIC_KEY = GENERAL_PUBLIC_KEY,
  };
  
  static const struct option options[] =
    {
      /* Name, args, flag, val */
      { "help", no_argument, NULL, OPT_HELP },
      { "version", no_argument, NULL, 'V' },
      { "private-rsa-key", no_argument, NULL, OPT_PRIVATE_RSA },
      { "public-rsa-key", no_argument, NULL, OPT_PUBLIC_RSA },
      { "private-dsa-key", no_argument, NULL, OPT_PRIVATE_DSA },
      { "public-key-info", no_argument, NULL, OPT_PUBLIC_KEY },
      { "base-64", no_argument, NULL, 'b' },
      { NULL, 0, NULL, 0 }
    };

  while ( (c = getopt_long(argc, argv, "Vb", options, NULL)) != -1)
    {
      switch (c)
	{
	default:
	  abort();

	case 'b':
	  base64 = 1;
	  break;

	case OPT_PRIVATE_RSA:
	case OPT_PUBLIC_RSA:
	case OPT_PRIVATE_DSA:
	case OPT_PUBLIC_KEY:
	  /* Same values as the type codes. */
	  type = c;
	  break;

	case OPT_HELP:
	  printf("FIXME: Usage information.\n");
	  return EXIT_SUCCESS;
	case '?':
	  return EXIT_FAILURE;

	case 'V':
	  printf("pkcs1-conv (" PACKAGE_STRING ")\n");
	  return EXIT_SUCCESS;
	}
    }

  nettle_buffer_init_realloc(&buffer, NULL, nettle_xrealloc);  

  if (optind == argc)
    {
      if (!convert_file(&buffer, stdin, type, base64))
	return EXIT_FAILURE;
    }
  else
    {
      int i;
      const char *mode = (type || base64) ? "r" : "rb";
      
      for (i = optind; i < argc; i++)
	{
	  FILE *f = fopen(argv[i], mode);
	  if (!f)
	    die("Failed to open `%s': %s.\n", argv[i], strerror(errno));

	  if (!convert_file(&buffer, f, type, base64))
	    return EXIT_FAILURE;

	  fclose(f);
	}
    }
  nettle_buffer_clear (&buffer);

  return EXIT_SUCCESS;
}
