/* certreqgen.c - Generate a key and a certification request
 *	Copyright (C) 2002 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of 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.
 *
 * GnuPG 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 a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

/*
The format of the native parameter file is follows:
  o Text only, line length is limited to about 1000 chars.
  o You must use UTF-8 encoding to specify non-ascii characters.
  o Empty lines are ignored.
  o Leading and trailing spaces are ignored.
  o A hash sign as the first non white space character is a comment line.
  o Control statements are indicated by a leading percent sign, the
    arguments are separated by white space from the keyword.
  o Parameters are specified by a keyword, followed by a colon.  Arguments
    are separated by white space.
  o The first parameter must be "Key-Type", control statements
    may be placed anywhere.
  o Key generation takes place when either the end of the parameter file
    is reached, the next "Key-Type" parameter is encountered or at the
    controlstatement "%commit"
  o Control statements:
    %echo <text>
	Print <text>.
    %dry-run
	Suppress actual key generation (useful for syntax checking).
    %commit
	Perform the key generation.  Note that an implicit commit is done
	at the next "Key-Type" parameter.
    %certfile <filename>
	Do not write the certificate to the keyDB but to <filename>.
        This must be given before the first
	commit to take place, duplicate specification of the same filename
	is ignored, the last filename before a commit is used.
	The filename is used until a new filename is used (at commit points)
	and all keys are written to that file.	If a new filename is given,
	this file is created (and overwrites an existing one).
	Both control statements must be given.
   o The order of the parameters does not matter except for "Key-Type"
     which must be the first parameter.  The parameters are only for the
     generated keyblock and parameters from previous key generations are not
     used. Some syntactically checks may be performed.
     The currently defined parameters are:
     Key-Type: <algo>
	Starts a new parameter block by giving the type of the
	primary key. The algorithm must be capable of signing.
	This is a required parameter.  For now the only supported
        algorithm is "rsa".
     Key-Length: <length-in-bits>
	Length of the key in bits.  Default is 1024.
     Key-Usage: <usage-list>
        Space or comma delimited list of key usage, allowed values are
        "encrypt" and "sign".  This is used to generate the KeyUsage extension.
        Please make sure that the algorithm is capable of this usage.  Default
        is to allow encrypt and sign.
     Name-DN: subject name
        This is the DN name of the subject in rfc2253 format.
     Name-Email: <string>
	The ist the email address

Here is an example:
$ cat >foo <<EOF
%echo Generating a standard key
Key-Type: RSA
Key-Length: 1024
Name-DN: CN=test cert 1,OU=Aegypten Project,O=g10 Code GmbH,L=Düsseldorf,C=DE
Name-Email: joe@foo.bar
# Do a commit here, so that we can later print "done" :-)
%commit
%echo done
EOF
*/


#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h> 
#include <time.h>
#include <assert.h>

#include <gcrypt.h>
#include <ksba.h>

#include "gpgsm.h"
#include "keydb.h"
#include "i18n.h"


enum para_name {
  pKEYTYPE,
  pKEYLENGTH,
  pKEYUSAGE,
  pNAMEDN,
  pNAMEEMAIL
};

struct para_data_s {
  struct para_data_s *next;
  int lnr;
  enum para_name key;
  union {
    unsigned int usage; 
    char value[1];
  } u;
};

struct reqgen_ctrl_s {
  int lnr;
  int dryrun;
  KsbaWriter writer;
};


static int proc_parameters (struct para_data_s *para,
                            struct reqgen_ctrl_s *outctrl);
static int create_request (struct para_data_s *para,
                           KsbaConstSexp public,
                           struct reqgen_ctrl_s *outctrl);



static void
release_parameter_list (struct para_data_s *r)
{
  struct para_data_s *r2;
  
  for (; r ; r = r2)
    {
      r2 = r->next;
      xfree(r);
    }
}

static struct para_data_s *
get_parameter (struct para_data_s *para, enum para_name key)
{
  struct para_data_s *r;
  
  for (r = para; r && r->key != key; r = r->next)
    ;
  return r;
}

static const char *
get_parameter_value (struct para_data_s *para, enum para_name key)
{
  struct para_data_s *r = get_parameter (para, key);
  return (r && *r->u.value)? r->u.value : NULL;
}

static int
get_parameter_algo (struct para_data_s *para, enum para_name key)
{
  struct para_data_s *r = get_parameter (para, key);
  if (!r)
    return -1;
  if (digitp (r->u.value))
    return atoi( r->u.value );
  return gcry_pk_map_name (r->u.value); 
}

/* parse the usage parameter.  Returns 0 on success.  Note that we
   only care about sign and encrypt and don't (yet) allow all the
   other X.509 usage to be specified; instead we will use a fixed
   mapping to the X.509 usage flags */
static int
parse_parameter_usage (struct para_data_s *para, enum para_name key)
{
  struct para_data_s *r = get_parameter (para, key);
  char *p, *pn;
  unsigned int use;
  
  if (!r)
    return 0; /* none (this is an optional parameter)*/
    
  use = 0;
  pn = r->u.value;
  while ( (p = strsep (&pn, " \t,")) )
    {
      if (!*p)
        ;
      else if ( !ascii_strcasecmp (p, "sign") )
        use |= GCRY_PK_USAGE_SIGN;
      else if ( !ascii_strcasecmp (p, "encrypt") )
        use |= GCRY_PK_USAGE_ENCR;
      else
        {
          log_error ("line %d: invalid usage list\n", r->lnr);
          return -1; /* error */
        }
    }
  r->u.usage = use;
  return 0;
}


static unsigned int
get_parameter_uint (struct para_data_s *para, enum para_name key)
{
  struct para_data_s *r = get_parameter (para, key);

  if (!r)
    return 0;

  return (unsigned int)strtoul (r->u.value, NULL, 10);
}



/* Read the certificate generation parameters from FP and genereate
   (all) certificate requests.  */
static int
read_parameters (FILE *fp, KsbaWriter writer)
{
  static struct {
    const char *name;
    enum para_name key;
  } keywords[] = {
    { "Key-Type",       pKEYTYPE},
    { "Key-Length",     pKEYLENGTH },
    { "Key-Usage",      pKEYUSAGE },
    { "Name-DN",        pNAMEDN },
    { "Name-Email",     pNAMEEMAIL },
    { NULL, 0 }
  };
  char line[1024], *p;
  const char *err = NULL;
  struct para_data_s *para, *r;
  int i;
  struct reqgen_ctrl_s outctrl;

  memset (&outctrl, 0, sizeof (outctrl));
  outctrl.writer = writer;

  err = NULL;
  para = NULL;
  while (fgets (line, DIM(line)-1, fp) )
    {
      char *keyword, *value;

      outctrl.lnr++;
      if (*line && line[strlen(line)-1] != '\n')
        {
          err = "line too long";
          break;
	}
      for (p=line; spacep (p); p++)
        ;
      if (!*p || *p == '#')
        continue;

      keyword = p;
      if (*keyword == '%')
        {
          for (; !spacep (p); p++)
            ;
          if (*p)
            *p++ = 0;
          for (; spacep (p); p++)
            ;
          value = p;
          trim_trailing_spaces (value);

          if (!ascii_strcasecmp (keyword, "%echo"))
            log_info ("%s\n", value);
          else if (!ascii_strcasecmp (keyword, "%dry-run"))
            outctrl.dryrun = 1;
          else if (!ascii_strcasecmp( keyword, "%commit"))
            {
              proc_parameters (para, &outctrl);
              /*FIXME: what about error handling */
              release_parameter_list (para);
              para = NULL;
	    }
          else
            log_info ("skipping control `%s' (%s)\n", keyword, value);

          continue;
	}


      if (!(p = strchr (p, ':')) || p == keyword)
        {
          err = "missing colon";
          break;
	}
      if (*p)
        *p++ = 0;
      for (; spacep (p); p++)
        ;
      if (!*p)
        {
          err = "missing argument";
          break;
	}
      value = p;
      trim_trailing_spaces (value);

      for (i=0; (keywords[i].name
                 && ascii_strcasecmp (keywords[i].name, keyword)); i++)
        ;
      if (!keywords[i].name)
        {
          err = "unknown keyword";
          break;
	}
      if (keywords[i].key != pKEYTYPE && !para)
        {
          err = "parameter block does not start with \"Key-Type\"";
          break;
	}

      if (keywords[i].key == pKEYTYPE && para)
        {
          proc_parameters (para, &outctrl);
          release_parameter_list (para);
          para = NULL;
	}
      else
        {
          for (r = para; r && r->key != keywords[i].key; r = r->next)
            ;
          if (r)
            {
              err = "duplicate keyword";
              break;
	    }
	}

      r = xtrycalloc (1, sizeof *r + strlen( value ));
      if (!r)
        {
          err = "out of core";
          break;
        }
      r->lnr = outctrl.lnr;
      r->key = keywords[i].key;
      strcpy (r->u.value, value);
      r->next = para;
      para = r;
    }

  if (err)
    log_error ("line %d: %s\n", outctrl.lnr, err);
  else if (ferror(fp))
    log_error ("line %d: read error: %s\n", outctrl.lnr, strerror(errno) );
  else if (para)
    {
      proc_parameters (para, &outctrl);
      /*FIXME: what about error handling */
    }

  release_parameter_list (para);
  return 0;
}

/* check whether there are invalid characters in the email address S */
static int
has_invalid_email_chars (const char *s)
{
  int at_seen=0;
  static char valid_chars[] = "01234567890_-."
                              "abcdefghijklmnopqrstuvwxyz"
			      "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  for (; *s; s++)
    {
      if (*s & 0x80)
        return 1;
      if (*s == '@')
        at_seen++;
      else if (!at_seen && !( !!strchr (valid_chars, *s) || *s == '+'))
        return 1;
      else if (at_seen && !strchr (valid_chars, *s))
        return 1;
    }
  return at_seen != 1;
}


/* Check that all required parameters are given and perform the action */
static int
proc_parameters (struct para_data_s *para, struct reqgen_ctrl_s *outctrl)
{
  struct para_data_s *r;
  const char *s;
  int i;
  unsigned int nbits;
  char numbuf[20];
  unsigned char keyparms[100];
  int rc;
  KsbaSexp public;
  
  /* check that we have all required parameters */
  assert (get_parameter (para, pKEYTYPE));

  /* We can only use RSA for now.  There is a with pkcs-10 on how to
     use ElGamal becuase it is expected that a PK algorithm can always
     be used for signing. */
  i = get_parameter_algo (para, pKEYTYPE);
  if (i < 1 || i != GCRY_PK_RSA )
    {
      r = get_parameter (para, pKEYTYPE);
      log_error ("line %d: invalid algorithm\n", r->lnr);
      return GNUPG_Invalid_Parameter;
    }
  
  /* check the keylength */
  if (!get_parameter (para, pKEYLENGTH))
    nbits = 1024;
  else
    nbits = get_parameter_uint (para, pKEYLENGTH);
  if (nbits < 512 || nbits > 4096)
    {
      r = get_parameter (para, pKEYTYPE);
      log_error ("line %d: invalid key length %u (valid are 512 to 4096)\n",
                 r->lnr, nbits);
      return GNUPG_Invalid_Parameter;
    }
    
  /* check the usage */
  if (parse_parameter_usage (para, pKEYUSAGE))
    return GNUPG_Invalid_Parameter;

  /* check that there is a subject name and that this DN fits our
     requirements */
  if (!(s=get_parameter_value (para, pNAMEDN)))
    {
      r = get_parameter (para, pKEYTYPE);
      log_error ("line %d: no subject name given\n", r->lnr);
      return GNUPG_Invalid_Parameter;
    }
  /* fixme check s */

  /* check that the optional email address is okay */
  if ((s=get_parameter_value (para, pNAMEEMAIL)))
    { 
      if (has_invalid_email_chars (s)
          || *s == '@'
          || s[strlen(s)-1] == '@'
          || s[strlen(s)-1] == '.'
          || strstr(s, ".."))
        {
          r = get_parameter (para, pKEYTYPE);
          log_error ("line %d: not a valid email address\n", r->lnr);
          return GNUPG_Invalid_Parameter;
        }
    }

  sprintf (numbuf, "%u", nbits);
  snprintf (keyparms, DIM (keyparms)-1, 
            "(6:genkey(3:rsa(5:nbits%d:%s)))", strlen (numbuf), numbuf);
  rc = gpgsm_agent_genkey (keyparms, &public);
  if (rc)
    {
      r = get_parameter (para, pKEYTYPE);
      log_error ("line %d: key generation failed: %s\n",
                 r->lnr, gnupg_strerror (rc));
      return rc;
    }

  rc = create_request (para, public, outctrl);
  xfree (public);

  return rc;
}


/* Parameters are checked, the key pair has been created.  Now
   generate the request and write it out */
static int
create_request (struct para_data_s *para, KsbaConstSexp public,
                struct reqgen_ctrl_s *outctrl)
{
  KsbaCertreq cr;
  KsbaError err;
  GCRY_MD_HD md;
  KsbaStopReason stopreason;
  int rc = 0;

  cr = ksba_certreq_new ();
  if (!cr)
    return seterr (Out_Of_Core);

  md = gcry_md_open (GCRY_MD_SHA1, 0);
  if (!md)
    {
      log_error ("md_open failed: %s\n", gcry_strerror (-1));
      rc = map_gcry_err (gcry_errno ());
      goto leave;
    }
  if (DBG_HASHING)
    gcry_md_start_debug (md, "cr.cri");

  ksba_certreq_set_hash_function (cr, HASH_FNC, md);
  ksba_certreq_set_writer (cr, outctrl->writer);
  
  err = ksba_certreq_set_subject (cr, get_parameter_value (para, pNAMEDN));
  if (err)
    {
      log_error ("error setting the subject's name: %s\n",
                 ksba_strerror (err));
      rc = map_ksba_err (err);
      goto leave;
    }

  err = ksba_certreq_set_public_key (cr, public);
  if (err)
    {
      log_error ("error setting the public key: %s\n",
                 ksba_strerror (err));
      rc = map_ksba_err (err);
      goto leave;
    }
               
  do
    {
      err = ksba_certreq_build (cr, &stopreason);
      if (err)
        {
          log_error ("ksba_certreq_build failed: %s\n", ksba_strerror (err));
          rc = map_ksba_err (err);
          goto leave;
        }
      if (stopreason == KSBA_SR_NEED_SIG)
        {
          GCRY_SEXP s_pkey;
          size_t n;
          unsigned char grip[20], hexgrip[41];
          char *sigval;
          size_t siglen;

          n = gcry_sexp_canon_len (public, 0, NULL, NULL);
          if (!n)
            {
              log_error ("libksba did not return a proper S-Exp\n");
              err = GNUPG_Bug;
              goto leave;
            }
          rc = gcry_sexp_sscan (&s_pkey, NULL, public, n);
          if (rc)
            {
              log_error ("gcry_sexp_scan failed: %s\n", gcry_strerror (rc));
              rc = map_gcry_err (rc);
              goto leave;
            }
          if ( !gcry_pk_get_keygrip (s_pkey, grip) )
            {
              rc = seterr (General_Error);
              log_error ("can't figure out the keygrip\n");
              gcry_sexp_release (s_pkey);
              goto leave;
            }
          gcry_sexp_release (s_pkey);
          for (n=0; n < 20; n++)
            sprintf (hexgrip+n*2, "%02X", grip[n]);

          rc = gpgsm_agent_pksign (hexgrip,
                                   gcry_md_read(md, GCRY_MD_SHA1), 
                                   gcry_md_get_algo_dlen (GCRY_MD_SHA1),
                                   GCRY_MD_SHA1,
                                   &sigval, &siglen);
          if (rc)
            {
              log_error ("signing failed: %s\n", gnupg_strerror (rc));
              goto leave;
            }
          
          err = ksba_certreq_set_sig_val (cr, sigval);
          xfree (sigval);
          if (err)
            {
              log_error ("failed to store the sig_val: %s\n",
                         ksba_strerror (err));
              rc = map_ksba_err (err);
              goto leave;
            }
        }
    }
  while (stopreason != KSBA_SR_READY);   
  

 leave:
  gcry_md_close (md);
  ksba_certreq_release (cr);
  return rc;  
}



/* Create a new key by reading the parameters from in_fd.  Multiple
   keys may be created */
int
gpgsm_genkey (CTRL ctrl, int in_fd, FILE *out_fp)
{
  int rc;
  FILE *in_fp;
  Base64Context b64writer = NULL;
  KsbaWriter writer;

  in_fp = fdopen (dup (in_fd), "rb");
  if (!in_fp)
    {
      log_error ("fdopen() failed: %s\n", strerror (errno));
      return seterr (IO_Error);
    }

  ctrl->pem_name = "NEW CERTIFICATE REQUEST";
  rc = gpgsm_create_writer (&b64writer, ctrl, out_fp, &writer);
  if (rc)
    {
      log_error ("can't create writer: %s\n", gnupg_strerror (rc));
      goto leave;
    }

  rc = read_parameters (in_fp, writer);
  if (rc)
    goto leave;

  rc = gpgsm_finish_writer (b64writer);
  if (rc) 
    {
      log_error ("write failed: %s\n", gnupg_strerror (rc));
      goto leave;
    }

  log_info ("certificate request created\n");

 leave:
  gpgsm_destroy_writer (b64writer);
  fclose (in_fp);
  return rc;
}