/* misc.c - miscellaneous functions
 * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
 *               2008, 2009, 2010 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#if defined(__linux__) && defined(__alpha__) && __GLIBC__ < 2
#include <asm/sysinfo.h>
#include <asm/unistd.h>
#endif
#ifdef HAVE_SETRLIMIT
#include <time.h>
#include <sys/time.h>
#include <sys/resource.h>
#endif
#ifdef ENABLE_SELINUX_HACKS
#include <sys/stat.h>
#endif

#ifdef HAVE_W32_SYSTEM
#include <time.h>
#include <process.h>
#include <windows.h>
#include <shlobj.h>
#ifndef CSIDL_APPDATA
#define CSIDL_APPDATA 0x001a
#endif
#ifndef CSIDL_LOCAL_APPDATA
#define CSIDL_LOCAL_APPDATA 0x001c
#endif
#ifndef CSIDL_FLAG_CREATE
#define CSIDL_FLAG_CREATE 0x8000
#endif
#endif /*HAVE_W32_SYSTEM*/

#include "gpg.h"
#ifdef HAVE_W32_SYSTEM
# include "status.h"
#endif /*HAVE_W32_SYSTEM*/
#include "util.h"
#include "main.h"
#include "photoid.h"
#include "options.h"
#include "call-agent.h"
#include "i18n.h"

#include <assert.h>

static int
string_count_chr (const char *string, int c)
{
  int count;

  for (count=0; *string; string++ )
    if ( *string == c )
      count++;
  return count;
}



#ifdef ENABLE_SELINUX_HACKS
/* A object and a global variable to keep track of files marked as
   secured. */
struct secured_file_item
{
  struct secured_file_item *next;
  ino_t ino;
  dev_t dev;
};
static struct secured_file_item *secured_files;
#endif /*ENABLE_SELINUX_HACKS*/




/* For the sake of SELinux we want to restrict access through gpg to
   certain files we keep under our own control.  This function
   registers such a file and is_secured_file may then be used to
   check whether a file has ben registered as secured. */
void
register_secured_file (const char *fname)
{
#ifdef ENABLE_SELINUX_HACKS
  struct stat buf;
  struct secured_file_item *sf;

  /* Note that we stop immediatley if something goes wrong here. */
  if (stat (fname, &buf))
    log_fatal (_("fstat of `%s' failed in %s: %s\n"), fname,
               "register_secured_file", strerror (errno));
/*   log_debug ("registering `%s' i=%lu.%lu\n", fname, */
/*              (unsigned long)buf.st_dev, (unsigned long)buf.st_ino); */
  for (sf=secured_files; sf; sf = sf->next)
    {
      if (sf->ino == buf.st_ino && sf->dev == buf.st_dev)
        return; /* Already registered.  */
    }

  sf = xmalloc (sizeof *sf);
  sf->ino = buf.st_ino;
  sf->dev = buf.st_dev;
  sf->next = secured_files;
  secured_files = sf;
#else /*!ENABLE_SELINUX_HACKS*/
  (void)fname;
#endif /*!ENABLE_SELINUX_HACKS*/
}

/* Remove a file registered as secure. */
void
unregister_secured_file (const char *fname)
{
#ifdef ENABLE_SELINUX_HACKS
  struct stat buf;
  struct secured_file_item *sf, *sfprev;

  if (stat (fname, &buf))
    {
      log_error (_("fstat of `%s' failed in %s: %s\n"), fname,
                 "unregister_secured_file", strerror (errno));
      return;
    }
/*   log_debug ("unregistering `%s' i=%lu.%lu\n", fname,  */
/*              (unsigned long)buf.st_dev, (unsigned long)buf.st_ino); */
  for (sfprev=NULL,sf=secured_files; sf; sfprev=sf, sf = sf->next)
    {
      if (sf->ino == buf.st_ino && sf->dev == buf.st_dev)
        {
          if (sfprev)
            sfprev->next = sf->next;
          else
            secured_files = sf->next;
          xfree (sf);
          return;
        }
    }
#else /*!ENABLE_SELINUX_HACKS*/
  (void)fname;
#endif /*!ENABLE_SELINUX_HACKS*/
}

/* Return true if FD is corresponds to a secured file.  Using -1 for
   FS is allowed and will return false. */
int
is_secured_file (int fd)
{
#ifdef ENABLE_SELINUX_HACKS
  struct stat buf;
  struct secured_file_item *sf;

  if (fd == -1)
    return 0; /* No file descriptor so it can't be secured either.  */

  /* Note that we print out a error here and claim that a file is
     secure if something went wrong. */
  if (fstat (fd, &buf))
    {
      log_error (_("fstat(%d) failed in %s: %s\n"), fd,
                 "is_secured_file", strerror (errno));
      return 1;
    }
/*   log_debug ("is_secured_file (%d) i=%lu.%lu\n", fd, */
/*              (unsigned long)buf.st_dev, (unsigned long)buf.st_ino); */
  for (sf=secured_files; sf; sf = sf->next)
    {
      if (sf->ino == buf.st_ino && sf->dev == buf.st_dev)
        return 1; /* Yes.  */
    }
#else /*!ENABLE_SELINUX_HACKS*/
  (void)fd;
#endif /*!ENABLE_SELINUX_HACKS*/
  return 0; /* No. */
}

/* Return true if FNAME is corresponds to a secured file.  Using NULL,
   "" or "-" for FS is allowed and will return false. This function is
   used before creating a file, thus it won't fail if the file does
   not exist. */
int
is_secured_filename (const char *fname)
{
#ifdef ENABLE_SELINUX_HACKS
  struct stat buf;
  struct secured_file_item *sf;

  if (iobuf_is_pipe_filename (fname) || !*fname)
    return 0;

  /* Note that we print out a error here and claim that a file is
     secure if something went wrong. */
  if (stat (fname, &buf))
    {
      if (errno == ENOENT || errno == EPERM || errno == EACCES)
        return 0;
      log_error (_("fstat of `%s' failed in %s: %s\n"), fname,
                 "is_secured_filename", strerror (errno));
      return 1;
    }
/*   log_debug ("is_secured_filename (%s) i=%lu.%lu\n", fname, */
/*              (unsigned long)buf.st_dev, (unsigned long)buf.st_ino); */
  for (sf=secured_files; sf; sf = sf->next)
    {
      if (sf->ino == buf.st_ino && sf->dev == buf.st_dev)
        return 1; /* Yes.  */
    }
#else /*!ENABLE_SELINUX_HACKS*/
  (void)fname;
#endif /*!ENABLE_SELINUX_HACKS*/
  return 0; /* No. */
}



u16
checksum_u16( unsigned n )
{
    u16 a;

    a  = (n >> 8) & 0xff;
    a += n & 0xff;
    return a;
}


u16
checksum( byte *p, unsigned n )
{
    u16 a;

    for(a=0; n; n-- )
	a += *p++;
    return a;
}

u16
checksum_mpi (gcry_mpi_t a)
{
  u16 csum;
  byte *buffer;
  size_t nbytes;

  if ( gcry_mpi_print (GCRYMPI_FMT_PGP, NULL, 0, &nbytes, a) )
    BUG ();
  /* Fixme: For numbers not in secure memory we should use a stack
   * based buffer and only allocate a larger one if mpi_print returns
   * an error. */
  buffer = (gcry_is_secure(a)?
            gcry_xmalloc_secure (nbytes) : gcry_xmalloc (nbytes));
  if ( gcry_mpi_print (GCRYMPI_FMT_PGP, buffer, nbytes, NULL, a) )
    BUG ();
  csum = checksum (buffer, nbytes);
  xfree (buffer);
  return csum;
}

u32
buffer_to_u32( const byte *buffer )
{
    unsigned long a;
    a =  *buffer << 24;
    a |= buffer[1] << 16;
    a |= buffer[2] << 8;
    a |= buffer[3];
    return a;
}

void
print_pubkey_algo_note( int algo )
{
  if(algo >= 100 && algo <= 110)
    {
      static int warn=0;
      if(!warn)
	{
	  warn=1;
	  log_info (_("WARNING: using experimental public key algorithm %s\n"),
		    openpgp_cipher_algo_name (algo));
	}
    }
  else if (algo == 20)
    {
      log_info (_("WARNING: Elgamal sign+encrypt keys are deprecated\n"));
    }
}

void
print_cipher_algo_note( int algo )
{
  if(algo >= 100 && algo <= 110)
    {
      static int warn=0;
      if(!warn)
	{
	  warn=1;
	  log_info (_("WARNING: using experimental cipher algorithm %s\n"),
                    openpgp_cipher_algo_name (algo));
	}
    }
}

void
print_digest_algo_note( int algo )
{
  if(algo >= 100 && algo <= 110)
    {
      static int warn=0;
      if(!warn)
	{
	  warn=1;
	  log_info (_("WARNING: using experimental digest algorithm %s\n"),
                    gcry_md_algo_name (algo));
	}
    }
  else if(algo==DIGEST_ALGO_MD5)
    log_info (_("WARNING: digest algorithm %s is deprecated\n"),
              gcry_md_algo_name (algo));
}


/* Map OpenPGP algo numbers to those used by Libgcrypt.  We need to do
   this for algorithms we implemented in Libgcrypt after they become
   part of OpenPGP.  */
int
map_cipher_openpgp_to_gcry (int algo)
{
  switch (algo)
    {
    case CIPHER_ALGO_CAMELLIA128: return 310;
    case CIPHER_ALGO_CAMELLIA192: return 311;
    case CIPHER_ALGO_CAMELLIA256: return 312;
    default: return algo;
    }
}

/* The inverse fucntion of above.  */
static int
map_cipher_gcry_to_openpgp (int algo)
{
  switch (algo)
    {
    case 310: return CIPHER_ALGO_CAMELLIA128;
    case 311: return CIPHER_ALGO_CAMELLIA192;
    case 312: return CIPHER_ALGO_CAMELLIA256;
    default: return algo;
    }
}

/* Map OpenPGP public key algorithm numbers to those used by
   Libgcrypt.  */
int
map_pk_openpgp_to_gcry (int algo)
{
  switch (algo)
    {
    case PUBKEY_ALGO_ECDSA: return GCRY_PK_ECDSA;
    case PUBKEY_ALGO_ECDH:  return GCRY_PK_ECDH;
    default: return algo;
    }
}

/* Map Gcrypt public key algorithm numbers to those used by
   OpenPGP.  */
int
map_pk_gcry_to_openpgp (enum gcry_pk_algos algo)
{
  switch (algo)
    {
    case GCRY_PK_ECDSA:  return PUBKEY_ALGO_ECDSA;
    case GCRY_PK_ECDH:   return PUBKEY_ALGO_ECDH;
    default: return algo < 110 ? algo : 0;
    }
}


/* Return the block length of an OpenPGP cipher algorithm.  */
int
openpgp_cipher_blocklen (int algo)
{
  /* We use the numbers from OpenPGP to be sure that we get the right
     block length.  This is so that the packet parsing code works even
     for unknown algorithms (for which we assume 8 due to tradition).

     NOTE: If you change the the returned blocklen above 16, check
     the callers because they may use a fixed size buffer of that
     size. */
  switch (algo)
    {
    case 7: case 8: case 9: /* AES */
    case 10: /* Twofish */
    case 11: case 12: case 13: /* Camellia */
      return 16;

    default:
      return 8;
    }
}

/****************
 * Wrapper around the libgcrypt function with additonal checks on
 * the OpenPGP contraints for the algo ID.
 */
int
openpgp_cipher_test_algo( int algo )
{
  /* (5 and 6 are marked reserved by rfc4880.)  */
  if ( algo < 0 || algo > 110 || algo == 5 || algo == 6 )
    return gpg_error (GPG_ERR_CIPHER_ALGO);

  return gcry_cipher_test_algo (map_cipher_openpgp_to_gcry (algo));
}

/* Map the OpenPGP cipher algorithm whose ID is contained in ALGORITHM to a
   string representation of the algorithm name.  For unknown algorithm
   IDs this function returns "?".  */
const char *
openpgp_cipher_algo_name (int algo)
{
  return gnupg_cipher_algo_name (map_cipher_openpgp_to_gcry (algo));
}

int
openpgp_pk_test_algo( int algo )
{
  /* Dont't allow type 20 keys unless in rfc2440 mode.  */
  if (!RFC2440 && algo == 20)
    return gpg_error (GPG_ERR_PUBKEY_ALGO);

  if (algo == GCRY_PK_ELG_E)
    algo = GCRY_PK_ELG;

  if (algo < 0 || algo > 110)
    return gpg_error (GPG_ERR_PUBKEY_ALGO);

  return gcry_pk_test_algo (map_pk_openpgp_to_gcry (algo));
}

int
openpgp_pk_test_algo2( int algo, unsigned int use )
{
  size_t use_buf = use;

  /* Dont't allow type 20 keys unless in rfc2440 mode.  */
  if (!RFC2440 && algo == 20)
    return gpg_error (GPG_ERR_PUBKEY_ALGO);

  if (algo == GCRY_PK_ELG_E)
    algo = GCRY_PK_ELG;

  if (algo < 0 || algo > 110)
    return gpg_error (GPG_ERR_PUBKEY_ALGO);

  return gcry_pk_algo_info (map_pk_openpgp_to_gcry (algo),
                            GCRYCTL_TEST_ALGO, NULL, &use_buf);
}

int
openpgp_pk_algo_usage ( int algo )
{
    int use = 0;

    /* They are hardwired in gpg 1.0. */
    switch ( algo ) {
      case PUBKEY_ALGO_RSA:
          use = (PUBKEY_USAGE_CERT | PUBKEY_USAGE_SIG
                 | PUBKEY_USAGE_ENC | PUBKEY_USAGE_AUTH);
          break;
      case PUBKEY_ALGO_RSA_E:
      case PUBKEY_ALGO_ECDH:
          use = PUBKEY_USAGE_ENC;
          break;
      case PUBKEY_ALGO_RSA_S:
          use = PUBKEY_USAGE_CERT | PUBKEY_USAGE_SIG;
          break;
      case PUBKEY_ALGO_ELGAMAL:
          if (RFC2440)
             use = PUBKEY_USAGE_ENC;
          break;
      case PUBKEY_ALGO_ELGAMAL_E:
          use = PUBKEY_USAGE_ENC;
          break;
      case PUBKEY_ALGO_DSA:
          use = PUBKEY_USAGE_CERT | PUBKEY_USAGE_SIG | PUBKEY_USAGE_AUTH;
          break;
      case PUBKEY_ALGO_ECDSA:
          use = PUBKEY_USAGE_CERT | PUBKEY_USAGE_SIG | PUBKEY_USAGE_AUTH;
      default:
          break;
    }
    return use;
}

/* Map the OpenPGP pubkey algorithm whose ID is contained in ALGO to a
   string representation of the algorithm name.  For unknown algorithm
   IDs this function returns "?".  */
const char *
openpgp_pk_algo_name (int algo)
{
  return gcry_pk_algo_name (map_pk_openpgp_to_gcry (algo));
}


int
openpgp_md_test_algo( int algo )
{
  /* Note: If the list of actual supported OpenPGP algorithms changes,
     make sure that our hard coded values at
     print_status_begin_signing() gets updated. */
  /* 4, 5, 6, 7 are defined by rfc2440 but will be removed from the
     next revision of the standard.  */
  if (algo < 0 || algo > 110 || (algo >= 4 && algo <= 7))
    return gpg_error (GPG_ERR_DIGEST_ALGO);
  return gcry_md_test_algo (algo);
}


/* Map the OpenPGP digest algorithm whose ID is contained in ALGO to a
   string representation of the algorithm name.  For unknown algorithm
   IDs this function returns "?".  */
const char *
openpgp_md_algo_name (int algo)
{
  if (algo < 0 || algo > 110)
    return "?";
  return gcry_md_algo_name (algo);
}


#ifdef USE_IDEA
/* Special warning for the IDEA cipher */
void
idea_cipher_warn(int show)
{
  static int warned=0;

  if(!warned || show)
    {
      log_info(_("the IDEA cipher plugin is not present\n"));
      log_info(_("please see %s for more information\n"),
               "http://www.gnupg.org/faq/why-not-idea.html");
      warned=1;
    }
}
#endif


static unsigned long
get_signature_count (PKT_public_key *pk)
{
#ifdef ENABLE_CARD_SUPPORT
  struct agent_card_info_s info;

  (void)pk;
  if (!agent_scd_getattr ("SIG-COUNTER",&info))
    return info.sig_counter;
  else
    return 0;
#else
  (void)pk;
  return 0;
#endif
}

/* Expand %-strings.  Returns a string which must be xfreed.  Returns
   NULL if the string cannot be expanded (too large). */
char *
pct_expando(const char *string,struct expando_args *args)
{
  const char *ch=string;
  int idx=0,maxlen=0,done=0;
  u32 pk_keyid[2]={0,0},sk_keyid[2]={0,0};
  char *ret=NULL;

  if(args->pk)
    keyid_from_pk(args->pk,pk_keyid);

  if(args->pksk)
    keyid_from_pk (args->pksk, sk_keyid);

  /* This is used so that %k works in photoid command strings in
     --list-secret-keys (which of course has a sk, but no pk). */
  if(!args->pk && args->pksk)
    keyid_from_pk (args->pksk, pk_keyid);

  while(*ch!='\0')
    {
      if(!done)
	{
	  /* 8192 is way bigger than we'll need here */
	  if(maxlen>=8192)
	    goto fail;

	  maxlen+=1024;
	  ret=xrealloc(ret,maxlen);
	}

      done=0;

      if(*ch=='%')
	{
	  switch(*(ch+1))
	    {
	    case 's': /* short key id */
	      if(idx+8<maxlen)
		{
		  sprintf(&ret[idx],"%08lX",(ulong)sk_keyid[1]);
		  idx+=8;
		  done=1;
		}
	      break;

	    case 'S': /* long key id */
	      if(idx+16<maxlen)
		{
		  sprintf(&ret[idx],"%08lX%08lX",
			  (ulong)sk_keyid[0],(ulong)sk_keyid[1]);
		  idx+=16;
		  done=1;
		}
	      break;

	    case 'k': /* short key id */
	      if(idx+8<maxlen)
		{
		  sprintf(&ret[idx],"%08lX",(ulong)pk_keyid[1]);
		  idx+=8;
		  done=1;
		}
	      break;

	    case 'K': /* long key id */
	      if(idx+16<maxlen)
		{
		  sprintf(&ret[idx],"%08lX%08lX",
			  (ulong)pk_keyid[0],(ulong)pk_keyid[1]);
		  idx+=16;
		  done=1;
		}
	      break;

	    case 'c': /* signature count from card, if any. */
	      if(idx+10<maxlen)
		{
		  sprintf (&ret[idx],"%lu", get_signature_count (args->pksk));
		  idx+=strlen(&ret[idx]);
		  done=1;
		}
	      break;

	    case 'p': /* primary pk fingerprint of a sk */
	    case 'f': /* pk fingerprint */
	    case 'g': /* sk fingerprint */
	      {
		byte array[MAX_FINGERPRINT_LEN];
		size_t len;
		int i;

		if((*(ch+1))=='p' && args->pksk)
		  {
		    if(args->pksk->flags.primary)
		      fingerprint_from_pk (args->pksk, array, &len);
		    else if (args->pksk->main_keyid[0]
                             || args->pksk->main_keyid[1])
		      {
                        /* FIXME: Document teh code and check whether
                           it is still needed.  */
			PKT_public_key *pk=
			  xmalloc_clear(sizeof(PKT_public_key));

			if (!get_pubkey_fast (pk,args->pksk->main_keyid))
			  fingerprint_from_pk (pk, array, &len);
			else
			  memset (array, 0, (len=MAX_FINGERPRINT_LEN));
			free_public_key (pk);
		      }
		    else
		      memset(array,0,(len=MAX_FINGERPRINT_LEN));
		  }
		else if((*(ch+1))=='f' && args->pk)
		  fingerprint_from_pk (args->pk, array, &len);
		else if((*(ch+1))=='g' && args->pksk)
		  fingerprint_from_pk (args->pksk, array, &len);
		else
		  memset(array,0,(len=MAX_FINGERPRINT_LEN));

		if(idx+(len*2)<maxlen)
		  {
		    for(i=0;i<len;i++)
		      {
			sprintf(&ret[idx],"%02X",array[i]);
			idx+=2;
		      }
		    done=1;
		  }
	      }
	      break;

	    case 'v': /* validity letters */
	      if(args->validity_info && idx+1<maxlen)
		{
		  ret[idx++]=args->validity_info;
		  ret[idx]='\0';
		  done=1;
		}
	      break;

	      /* The text string types */
	    case 't':
	    case 'T':
	    case 'V':
	      {
		const char *str=NULL;

		switch(*(ch+1))
		  {
		  case 't': /* e.g. "jpg" */
		    str=image_type_to_string(args->imagetype,0);
		    break;

		  case 'T': /* e.g. "image/jpeg" */
		    str=image_type_to_string(args->imagetype,2);
		    break;

		  case 'V': /* e.g. "full", "expired", etc. */
		    str=args->validity_string;
		    break;
		  }

		if(str && idx+strlen(str)<maxlen)
		  {
		    strcpy(&ret[idx],str);
		    idx+=strlen(str);
		    done=1;
		  }
	      }
	      break;

	    case '%':
	      if(idx+1<maxlen)
		{
		  ret[idx++]='%';
		  ret[idx]='\0';
		  done=1;
		}
	      break;

	      /* Any unknown %-keys (like %i, %o, %I, and %O) are
		 passed through for later expansion.  Note this also
		 handles the case where the last character in the
		 string is a '%' - the terminating \0 will end up here
		 and properly terminate the string. */
	    default:
	      if(idx+2<maxlen)
		{
		  ret[idx++]='%';
		  ret[idx++]=*(ch+1);
		  ret[idx]='\0';
		  done=1;
		}
	      break;
	      }

	  if(done)
	    ch++;
	}
      else
	{
	  if(idx+1<maxlen)
	    {
	      ret[idx++]=*ch;
	      ret[idx]='\0';
	      done=1;
	    }
	}

      if(done)
	ch++;
    }

  return ret;

 fail:
  xfree(ret);
  return NULL;
}

void
deprecated_warning(const char *configname,unsigned int configlineno,
		   const char *option,const char *repl1,const char *repl2)
{
  if(configname)
    {
      if(strncmp("--",option,2)==0)
	option+=2;

      if(strncmp("--",repl1,2)==0)
	repl1+=2;

      log_info(_("%s:%d: deprecated option \"%s\"\n"),
	       configname,configlineno,option);
    }
  else
    log_info(_("WARNING: \"%s\" is a deprecated option\n"),option);

  log_info(_("please use \"%s%s\" instead\n"),repl1,repl2);
}


void
deprecated_command (const char *name)
{
  log_info(_("WARNING: \"%s\" is a deprecated command - do not use it\n"),
           name);
}


void
obsolete_option (const char *configname, unsigned int configlineno,
                 const char *name)
{
  if(configname)
    log_info (_("%s:%u: obsolete option \"%s\" - it has no effect\n"),
              configname, configlineno, name);
  else
    log_info (_("WARNING: \"%s\" is an obsolete option - it has no effect\n"),
              name);
}


/*
 * Wrapper around gcry_cipher_map_name to provide a fallback using the
 * "Sn" syntax as used by the preference strings.
 */
int
string_to_cipher_algo (const char *string)
{
  int val;

  val = map_cipher_gcry_to_openpgp (gcry_cipher_map_name (string));
  if (!val && string && (string[0]=='S' || string[0]=='s'))
    {
      char *endptr;

      string++;
      val = strtol (string, &endptr, 10);
      if (!*string || *endptr || openpgp_cipher_test_algo (val))
        val = 0;
    }

  return val;
}

/*
 * Wrapper around gcry_md_map_name to provide a fallback using the
 * "Hn" syntax as used by the preference strings.
 */
int
string_to_digest_algo (const char *string)
{
  int val;

  val = gcry_md_map_name (string);
  if (!val && string && (string[0]=='H' || string[0]=='h'))
    {
      char *endptr;

      string++;
      val = strtol (string, &endptr, 10);
      if (!*string || *endptr || openpgp_md_test_algo (val))
        val = 0;
    }

  return val;
}



const char *
compress_algo_to_string(int algo)
{
  const char *s=NULL;

  switch(algo)
    {
    case COMPRESS_ALGO_NONE:
      s=_("Uncompressed");
      break;

    case COMPRESS_ALGO_ZIP:
      s="ZIP";
      break;

    case COMPRESS_ALGO_ZLIB:
      s="ZLIB";
      break;

#ifdef HAVE_BZIP2
    case COMPRESS_ALGO_BZIP2:
      s="BZIP2";
      break;
#endif
    }

  return s;
}

int
string_to_compress_algo(const char *string)
{
  /* TRANSLATORS: See doc/TRANSLATE about this string. */
  if(match_multistr(_("uncompressed|none"),string))
    return 0;
  else if(ascii_strcasecmp(string,"uncompressed")==0)
    return 0;
  else if(ascii_strcasecmp(string,"none")==0)
    return 0;
  else if(ascii_strcasecmp(string,"zip")==0)
    return 1;
  else if(ascii_strcasecmp(string,"zlib")==0)
    return 2;
#ifdef HAVE_BZIP2
  else if(ascii_strcasecmp(string,"bzip2")==0)
    return 3;
#endif
  else if(ascii_strcasecmp(string,"z0")==0)
    return 0;
  else if(ascii_strcasecmp(string,"z1")==0)
    return 1;
  else if(ascii_strcasecmp(string,"z2")==0)
    return 2;
#ifdef HAVE_BZIP2
  else if(ascii_strcasecmp(string,"z3")==0)
    return 3;
#endif
  else
    return -1;
}

int
check_compress_algo(int algo)
{
  switch (algo)
    {
    case 0: return 0;
#ifdef HAVE_ZIP
    case 1:
    case 2: return 0;
#endif
#ifdef HAVE_BZIP2
    case 3: return 0;
#endif
    default: return G10ERR_COMPR_ALGO;
    }
}

int
default_cipher_algo(void)
{
  if(opt.def_cipher_algo)
    return opt.def_cipher_algo;
  else if(opt.personal_cipher_prefs)
    return opt.personal_cipher_prefs[0].value;
  else
    return opt.s2k_cipher_algo;
}

/* There is no default_digest_algo function, but see
   sign.c:hash_for() */

int
default_compress_algo(void)
{
  if(opt.compress_algo!=-1)
    return opt.compress_algo;
  else if(opt.personal_compress_prefs)
    return opt.personal_compress_prefs[0].value;
  else
    return DEFAULT_COMPRESS_ALGO;
}

const char *
compliance_option_string(void)
{
  char *ver="???";

  switch(opt.compliance)
    {
    case CO_GNUPG:   return "--gnupg";
    case CO_RFC4880: return "--openpgp";
    case CO_RFC2440: return "--rfc2440";
    case CO_RFC1991: return "--rfc1991";
    case CO_PGP2:    return "--pgp2";
    case CO_PGP6:    return "--pgp6";
    case CO_PGP7:    return "--pgp7";
    case CO_PGP8:    return "--pgp8";
    }

  return ver;
}

void
compliance_failure(void)
{
  char *ver="???";

  switch(opt.compliance)
    {
    case CO_GNUPG:
      ver="GnuPG";
      break;

    case CO_RFC4880:
      ver="OpenPGP";
      break;

    case CO_RFC2440:
      ver="OpenPGP (older)";
      break;

    case CO_RFC1991:
      ver="old PGP";
      break;

    case CO_PGP2:
      ver="PGP 2.x";
      break;

    case CO_PGP6:
      ver="PGP 6.x";
      break;

    case CO_PGP7:
      ver="PGP 7.x";
      break;

    case CO_PGP8:
      ver="PGP 8.x";
      break;
    }

  log_info(_("this message may not be usable by %s\n"),ver);
  opt.compliance=CO_GNUPG;
}

/* Break a string into successive option pieces.  Accepts single word
   options and key=value argument options. */
char *
optsep(char **stringp)
{
  char *tok,*end;

  tok=*stringp;
  if(tok)
    {
      end=strpbrk(tok," ,=");
      if(end)
	{
	  int sawequals=0;
	  char *ptr=end;

	  /* what we need to do now is scan along starting with *end,
	     If the next character we see (ignoring spaces) is an =
	     sign, then there is an argument. */

	  while(*ptr)
	    {
	      if(*ptr=='=')
		sawequals=1;
	      else if(*ptr!=' ')
		break;
	      ptr++;
	    }

	  /* There is an argument, so grab that too.  At this point,
	     ptr points to the first character of the argument. */
	  if(sawequals)
	    {
	      /* Is it a quoted argument? */
	      if(*ptr=='"')
		{
		  ptr++;
		  end=strchr(ptr,'"');
		  if(end)
		    end++;
		}
	      else
		end=strpbrk(ptr," ,");
	    }

	  if(end && *end)
	    {
	      *end='\0';
	      *stringp=end+1;
	    }
	  else
	    *stringp=NULL;
	}
      else
	*stringp=NULL;
    }

  return tok;
}

/* Breaks an option value into key and value.  Returns NULL if there
   is no value.  Note that "string" is modified to remove the =value
   part. */
char *
argsplit(char *string)
{
  char *equals,*arg=NULL;

  equals=strchr(string,'=');
  if(equals)
    {
      char *quote,*space;

      *equals='\0';
      arg=equals+1;

      /* Quoted arg? */
      quote=strchr(arg,'"');
      if(quote)
	{
	  arg=quote+1;

	  quote=strchr(arg,'"');
	  if(quote)
	    *quote='\0';
	}
      else
	{
	  size_t spaces;

	  /* Trim leading spaces off of the arg */
	  spaces=strspn(arg," ");
	  arg+=spaces;
	}

      /* Trim tailing spaces off of the tag */
      space=strchr(string,' ');
      if(space)
	*space='\0';
    }

  return arg;
}

/* Return the length of the initial token, leaving off any
   argument. */
static size_t
optlen(const char *s)
{
  char *end=strpbrk(s," =");

  if(end)
    return end-s;
  else
    return strlen(s);
}

int
parse_options(char *str,unsigned int *options,
	      struct parse_options *opts,int noisy)
{
  char *tok;

  if (str && !strcmp (str, "help"))
    {
      int i,maxlen=0;

      /* Figure out the longest option name so we can line these up
	 neatly. */
      for(i=0;opts[i].name;i++)
	if(opts[i].help && maxlen<strlen(opts[i].name))
	  maxlen=strlen(opts[i].name);

      for(i=0;opts[i].name;i++)
        if(opts[i].help)
	  printf("%s%*s%s\n",opts[i].name,
		 maxlen+2-(int)strlen(opts[i].name),"",_(opts[i].help));

      g10_exit(0);
    }

  while((tok=optsep(&str)))
    {
      int i,rev=0;
      char *otok=tok;

      if(tok[0]=='\0')
	continue;

      if(ascii_strncasecmp("no-",tok,3)==0)
	{
	  rev=1;
	  tok+=3;
	}

      for(i=0;opts[i].name;i++)
	{
	  size_t toklen=optlen(tok);

	  if(ascii_strncasecmp(opts[i].name,tok,toklen)==0)
	    {
	      /* We have a match, but it might be incomplete */
	      if(toklen!=strlen(opts[i].name))
		{
		  int j;

		  for(j=i+1;opts[j].name;j++)
		    {
		      if(ascii_strncasecmp(opts[j].name,tok,toklen)==0)
			{
			  if(noisy)
			    log_info(_("ambiguous option `%s'\n"),otok);
			  return 0;
			}
		    }
		}

	      if(rev)
		{
		  *options&=~opts[i].bit;
		  if(opts[i].value)
		    *opts[i].value=NULL;
		}
	      else
		{
		  *options|=opts[i].bit;
		  if(opts[i].value)
		    *opts[i].value=argsplit(tok);
		}
	      break;
	    }
	}

      if(!opts[i].name)
	{
	  if(noisy)
	    log_info(_("unknown option `%s'\n"),otok);
	  return 0;
	}
    }

  return 1;
}


/* Check whether the string has characters not valid in an RFC-822
   address.  To cope with OpenPGP we ignore non-ascii characters
   so that for example umlauts are legal in an email address.  An
   OpenPGP user ID must be utf-8 encoded but there is no strict
   requirement for RFC-822.  Thus to avoid IDNA encoding we put the
   address verbatim as utf-8 into the user ID under the assumption
   that mail programs handle IDNA at a lower level and take OpenPGP
   user IDs as utf-8.  Note that we can't do an utf-8 encoding
   checking here because in keygen.c this function is called with the
   native encoding and native to utf-8 encoding is only done  later.  */
int
has_invalid_email_chars (const char *s)
{
  int at_seen=0;
  const char *valid_chars=
    "01234567890_-.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

  for ( ; *s; s++ )
    {
      if ( (*s & 0x80) )
        continue; /* We only care about ASCII.  */
      if ( *s == '@' )
        at_seen=1;
      else if ( !at_seen && !(strchr (valid_chars, *s)
                              || strchr ("!#$%&'*+/=?^`{|}~", *s)))
        return 1;
      else if ( at_seen && !strchr( valid_chars, *s ) )
        return 1;
    }
  return 0;
}


/* Check whether NAME represents a valid mailbox according to
   RFC822. Returns true if so. */
int
is_valid_mailbox (const char *name)
{
  return !( !name
            || !*name
            || has_invalid_email_chars (name)
            || string_count_chr (name,'@') != 1
            || *name == '@'
            || name[strlen(name)-1] == '@'
            || name[strlen(name)-1] == '.'
            || strstr (name, "..") );
}


/* Similar to access(2), but uses PATH to find the file. */
int
path_access(const char *file,int mode)
{
  char *envpath;
  int ret=-1;

  envpath=getenv("PATH");

  if(!envpath
#ifdef HAVE_DRIVE_LETTERS
     || (((file[0]>='A' && file[0]<='Z')
	  || (file[0]>='a' && file[0]<='z'))
	 && file[1]==':')
#else
     || file[0]=='/'
#endif
     )
    return access(file,mode);
  else
    {
      /* At least as large as, but most often larger than we need. */
      char *buffer=xmalloc(strlen(envpath)+1+strlen(file)+1);
      char *split,*item,*path=xstrdup(envpath);

      split=path;

      while((item=strsep(&split,PATHSEP_S)))
	{
	  strcpy(buffer,item);
	  strcat(buffer,"/");
	  strcat(buffer,file);
	  ret=access(buffer,mode);
	  if(ret==0)
	    break;
	}

      xfree(path);
      xfree(buffer);
    }

  return ret;
}



/* Return the number of public key parameters as used by OpenPGP.  */
int
pubkey_get_npkey (int algo)
{
  size_t n;

  /* ECC is special.  */
  if (algo == PUBKEY_ALGO_ECDSA)
    return 2;
  else if (algo == PUBKEY_ALGO_ECDH)
    return 3;

  /* All other algorithms match those of Libgcrypt.  */
  if (algo == GCRY_PK_ELG_E)
    algo = GCRY_PK_ELG;

  if (gcry_pk_algo_info (algo, GCRYCTL_GET_ALGO_NPKEY, NULL, &n))
    n = 0;
  return n;
}


/* Return the number of secret key parameters as used by OpenPGP.  */
int
pubkey_get_nskey (int algo)
{
  size_t n;

  /* ECC is special.  */
  if (algo == PUBKEY_ALGO_ECDSA)
    return 3;
  else if (algo == PUBKEY_ALGO_ECDH)
    return 4;

  /* All other algorithms match those of Libgcrypt.  */
  if (algo == GCRY_PK_ELG_E)
    algo = GCRY_PK_ELG;

  if (gcry_pk_algo_info( algo, GCRYCTL_GET_ALGO_NSKEY, NULL, &n ))
    n = 0;
  return n;
}

/* Temporary helper. */
int
pubkey_get_nsig (int algo)
{
  size_t n;

  /* ECC is special.  */
  if (algo == PUBKEY_ALGO_ECDSA)
    return 2;
  else if (algo == PUBKEY_ALGO_ECDH)
    return 0;

  if (algo == GCRY_PK_ELG_E)
    algo = GCRY_PK_ELG;

  if (gcry_pk_algo_info( algo, GCRYCTL_GET_ALGO_NSIGN, NULL, &n))
    n = 0;
  return n;
}


/* Temporary helper. */
int
pubkey_get_nenc (int algo)
{
  size_t n;

  /* ECC is special.  */
  if (algo == PUBKEY_ALGO_ECDSA)
    return 0;
  else if (algo == PUBKEY_ALGO_ECDH)
    return 2;

  if (algo == GCRY_PK_ELG_E)
    algo = GCRY_PK_ELG;

  if (gcry_pk_algo_info( algo, GCRYCTL_GET_ALGO_NENCR, NULL, &n ))
    n = 0;
  return n;
}


/* Temporary helper. */
unsigned int
pubkey_nbits( int algo, gcry_mpi_t *key )
{
    int rc, nbits;
    gcry_sexp_t sexp;

    if( algo == PUBKEY_ALGO_DSA ) {
	rc = gcry_sexp_build ( &sexp, NULL,
			      "(public-key(dsa(p%m)(q%m)(g%m)(y%m)))",
				  key[0], key[1], key[2], key[3] );
    }
    else if( algo == PUBKEY_ALGO_ELGAMAL || algo == PUBKEY_ALGO_ELGAMAL_E ) {
	rc = gcry_sexp_build ( &sexp, NULL,
			      "(public-key(elg(p%m)(g%m)(y%m)))",
				  key[0], key[1], key[2] );
    }
    else if( is_RSA (algo) ) {
	rc = gcry_sexp_build ( &sexp, NULL,
			      "(public-key(rsa(n%m)(e%m)))",
				  key[0], key[1] );
    }
    else if( algo == PUBKEY_ALGO_ECDSA || algo == PUBKEY_ALGO_ECDH ) {
        char *curve = openpgp_oid_to_str (key[0]);
        if (!curve)
          rc = gpg_error_from_syserror ();
        else
          {
            rc = gcry_sexp_build (&sexp, NULL,
                                  "(public-key(ecc(curve%s)(q%m)))",
				  curve, key[1]);
            xfree (curve);
          }
    }
    else
	return 0;

    if ( rc )
	BUG ();

    nbits = gcry_pk_get_nbits( sexp );
    gcry_sexp_release( sexp );
    return nbits;
}



int
mpi_print (estream_t fp, gcry_mpi_t a, int mode)
{
  int n=0;

  if (!a)
    return es_fprintf (fp, "[MPI_NULL]");
  if (!mode)
    {
      unsigned int n1;
      n1 = gcry_mpi_get_nbits(a);
      n += es_fprintf (fp, "[%u bits]", n1);
    }
  else if (gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
    {
      unsigned int nbits;
      unsigned char *p = gcry_mpi_get_opaque (a, &nbits);
      if (!p)
        n += es_fprintf (fp, "[invalid opaque value]");
      else
        {
          nbits = (nbits + 7)/8;
          for (; nbits; nbits--, p++)
            n += es_fprintf (fp, "%02X", *p);
        }
    }
  else
    {
      unsigned char *buffer;

      if (gcry_mpi_aprint (GCRYMPI_FMT_HEX, &buffer, NULL, a))
        BUG ();
      es_fputs (buffer, fp);
      n += strlen (buffer);
      gcry_free (buffer);
    }
  return n;
}


/* pkey[1] or skey[1] is Q for ECDSA, which is an uncompressed point,
   i.e.  04 <x> <y> */
unsigned int
ecdsa_qbits_from_Q (unsigned int qbits)
{
  if ((qbits%8) > 3)
    {
      log_error (_("ECDSA public key is expected to be in SEC encoding "
                   "multiple of 8 bits\n"));
      return 0;
    }
  qbits -= qbits%8;
  qbits /= 2;
  return qbits;
}