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533 lines
12 KiB
C
533 lines
12 KiB
C
/* md.c - message digest dispatcher
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* Copyright (C) 1998, 1999, 2002 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <assert.h>
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#include "util.h"
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#include "cipher.h"
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#include "errors.h"
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#include "algorithms.h"
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#include "i18n.h"
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/****************
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* This structure is used for the list of available algorithms
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* and for the list of algorithms in MD_HANDLE.
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*/
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struct md_digest_list_s {
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struct md_digest_list_s *next;
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const char *name;
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int algo;
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byte *asnoid;
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int asnlen;
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int mdlen;
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void (*init)( void *c );
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void (*write)( void *c, byte *buf, size_t nbytes );
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void (*final)( void *c );
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byte *(*read)( void *c );
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size_t contextsize; /* allocate this amount of context */
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PROPERLY_ALIGNED_TYPE context;
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};
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static struct md_digest_list_s *digest_list;
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static struct md_digest_list_s *
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new_list_item (int algo,
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const char *(*get_info)( int, size_t*,byte**, int*, int*,
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void (**)(void*),
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void (**)(void*,byte*,size_t),
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void (**)(void*),byte *(**)(void*)))
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{
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struct md_digest_list_s *r;
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r = m_alloc_clear (sizeof *r );
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r->algo = algo;
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r->name = (*get_info)( algo, &r->contextsize,
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&r->asnoid, &r->asnlen, &r->mdlen,
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&r->init, &r->write, &r->final, &r->read );
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if (!r->name )
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{
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m_free(r);
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r = NULL;
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}
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if (r)
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{
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r->next = digest_list;
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digest_list = r;
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}
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return r;
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}
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/*
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Load all available hash algorithms and return true. Subsequent
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calls will return 0.
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*/
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static int
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load_digest_module (void)
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{
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static int initialized = 0;
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if (initialized)
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return 0;
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initialized = 1;
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/* We load them in reverse order so that the most
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frequently used are the first in the list. */
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#ifdef USE_TIGER
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if (!new_list_item (DIGEST_ALGO_TIGER, tiger_get_info))
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BUG();
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#endif
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#ifdef USE_SHA512
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if (!new_list_item (DIGEST_ALGO_SHA512, sha512_get_info))
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BUG ();
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if (!new_list_item (DIGEST_ALGO_SHA384, sha384_get_info))
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BUG ();
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#endif
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if (!new_list_item (DIGEST_ALGO_SHA256, sha256_get_info))
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BUG ();
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if (!new_list_item (DIGEST_ALGO_MD5, md5_get_info))
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BUG ();
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if (!new_list_item (DIGEST_ALGO_RMD160, rmd160_get_info))
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BUG ();
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if (!new_list_item (DIGEST_ALGO_SHA1, sha1_get_info))
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BUG ();
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return 1;
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}
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/****************
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* Map a string to the digest algo */
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int
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string_to_digest_algo( const char *string )
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{
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struct md_digest_list_s *r;
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/* Hi there. I see you changing that code so you can use the new
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SHA hashes. Before you do it, please think about it. There
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are no official releases of any OpenPGP programs that generate
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these hashes, and we're trying to get a code base that can
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understand the hashes before we release one that generates
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them. - dshaw */
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if(!ascii_strcasecmp("sha256",string)
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|| !ascii_strcasecmp("sha384",string)
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|| !ascii_strcasecmp("sha512",string))
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{
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log_info(_("digest algorithm `%s' is read-only in this release\n"),
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string);
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return 0;
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}
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do {
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for(r = digest_list; r; r = r->next )
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if( !ascii_strcasecmp( r->name, string ) )
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return r->algo;
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} while( !r && load_digest_module () );
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return 0;
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}
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/****************
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* Map a digest algo to a string
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*/
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const char *
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digest_algo_to_string( int algo )
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{
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struct md_digest_list_s *r;
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do {
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for(r = digest_list; r; r = r->next )
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if( r->algo == algo )
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return r->name;
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} while( !r && load_digest_module () );
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return NULL;
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}
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int
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check_digest_algo( int algo )
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{
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struct md_digest_list_s *r;
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do {
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for(r = digest_list; r; r = r->next )
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if( r->algo == algo )
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return 0;
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} while( !r && load_digest_module () );
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return G10ERR_DIGEST_ALGO;
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}
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/****************
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* Open a message digest handle for use with algorithm ALGO.
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* More algorithms may be added by md_enable(). The initial algorithm
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* may be 0.
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*/
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MD_HANDLE
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md_open( int algo, int secure )
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{
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MD_HANDLE hd;
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int bufsize;
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if( secure ) {
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bufsize = 512 - sizeof( *hd );
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hd = m_alloc_secure_clear( sizeof *hd + bufsize );
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}
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else {
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bufsize = 1024 - sizeof( *hd );
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hd = m_alloc_clear( sizeof *hd + bufsize );
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}
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hd->bufsize = bufsize+1; /* hd has already one byte allocated */
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hd->secure = secure;
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if( algo )
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md_enable( hd, algo );
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fast_random_poll();
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return hd;
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}
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void
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md_enable( MD_HANDLE h, int algo )
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{
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struct md_digest_list_s *r, *ac;
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for( ac=h->list; ac; ac = ac->next )
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if( ac->algo == algo )
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return ; /* already enabled */
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/* find the algorithm */
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do {
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for(r = digest_list; r; r = r->next )
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if( r->algo == algo )
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break;
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} while( !r && load_digest_module () );
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if( !r ) {
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log_error("md_enable: algorithm %d not available\n", algo );
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return;
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}
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/* and allocate a new list entry */
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ac = h->secure? m_alloc_secure( sizeof *ac + r->contextsize
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- sizeof(r->context) )
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: m_alloc( sizeof *ac + r->contextsize
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- sizeof(r->context) );
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*ac = *r;
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ac->next = h->list;
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h->list = ac;
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/* and init this instance */
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(*ac->init)( &ac->context.c );
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}
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MD_HANDLE
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md_copy( MD_HANDLE a )
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{
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MD_HANDLE b;
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struct md_digest_list_s *ar, *br;
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if( a->bufcount )
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md_write( a, NULL, 0 );
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b = a->secure ? m_alloc_secure( sizeof *b + a->bufsize - 1 )
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: m_alloc( sizeof *b + a->bufsize - 1 );
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memcpy( b, a, sizeof *a + a->bufsize - 1 );
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b->list = NULL;
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b->debug = NULL;
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/* and now copy the complete list of algorithms */
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/* I know that the copied list is reversed, but that doesn't matter */
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for( ar=a->list; ar; ar = ar->next ) {
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br = a->secure ? m_alloc_secure( sizeof *br + ar->contextsize
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- sizeof(ar->context) )
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: m_alloc( sizeof *br + ar->contextsize
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- sizeof(ar->context) );
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memcpy( br, ar, sizeof(*br) + ar->contextsize
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- sizeof(ar->context) );
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br->next = b->list;
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b->list = br;
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}
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if( a->debug )
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md_start_debug( b, "unknown" );
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return b;
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}
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/****************
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* Reset all contexts and discard any buffered stuff. This may be used
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* instead of a md_close(); md_open().
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*/
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void
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md_reset( MD_HANDLE a )
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{
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struct md_digest_list_s *r;
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a->bufcount = a->finalized = 0;
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for( r=a->list; r; r = r->next ) {
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memset( r->context.c, 0, r->contextsize );
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(*r->init)( &r->context.c );
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}
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}
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void
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md_close(MD_HANDLE a)
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{
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struct md_digest_list_s *r, *r2;
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if( !a )
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return;
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if( a->debug )
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md_stop_debug(a);
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for(r=a->list; r; r = r2 ) {
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r2 = r->next;
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m_free(r);
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}
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m_free(a);
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}
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void
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md_write( MD_HANDLE a, const byte *inbuf, size_t inlen)
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{
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struct md_digest_list_s *r;
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if( a->debug ) {
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if( a->bufcount && fwrite(a->buffer, a->bufcount, 1, a->debug ) != 1 )
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BUG();
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if( inlen && fwrite(inbuf, inlen, 1, a->debug ) != 1 )
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BUG();
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}
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for(r=a->list; r; r = r->next ) {
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(*r->write)( &r->context.c, a->buffer, a->bufcount );
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/* Fixme: all ->write fnc should take a const byte* */
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(*r->write)( &r->context.c, (byte*)inbuf, inlen );
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}
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a->bufcount = 0;
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}
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void
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md_final(MD_HANDLE a)
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{
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struct md_digest_list_s *r;
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if( a->finalized )
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return;
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if( a->bufcount )
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md_write( a, NULL, 0 );
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for(r=a->list; r; r = r->next ) {
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(*r->final)( &r->context.c );
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}
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a->finalized = 1;
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}
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/****************
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* if ALGO is null get the digest for the used algo (which should be only one)
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*/
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byte *
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md_read( MD_HANDLE a, int algo )
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{
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struct md_digest_list_s *r;
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if( !algo ) { /* return the first algorithm */
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if( (r=a->list) ) {
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if( r->next )
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log_debug("more than algorithm in md_read(0)\n");
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return (*r->read)( &r->context.c );
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}
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}
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else {
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for(r=a->list; r; r = r->next )
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if( r->algo == algo )
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return (*r->read)( &r->context.c );
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}
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BUG();
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return NULL;
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}
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/****************
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* This function combines md_final and md_read but keeps the context
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* intact. This function can be used to calculate intermediate
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* digests. The digest is copied into buffer and the digestlength is
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* returned. If buffer is NULL only the needed size for buffer is returned.
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* buflen gives the max size of buffer. If the buffer is too shourt to
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* hold the complete digest, the buffer is filled with as many bytes are
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* possible and this value is returned.
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*/
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int
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md_digest( MD_HANDLE a, int algo, byte *buffer, int buflen )
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{
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struct md_digest_list_s *r = NULL;
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char *context;
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char *digest;
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if( a->bufcount )
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md_write( a, NULL, 0 );
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if( !algo ) { /* return digest for the first algorithm */
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if( (r=a->list) && r->next )
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log_debug("more than algorithm in md_digest(0)\n");
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}
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else {
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for(r=a->list; r; r = r->next )
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if( r->algo == algo )
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break;
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}
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if( !r )
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BUG();
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if( !buffer )
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return r->mdlen;
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/* I don't want to change the interface, so I simply work on a copy
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* the context (extra overhead - should be fixed)*/
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context = a->secure ? m_alloc_secure( r->contextsize )
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: m_alloc( r->contextsize );
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memcpy( context, r->context.c, r->contextsize );
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(*r->final)( context );
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digest = (*r->read)( context );
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if( buflen > r->mdlen )
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buflen = r->mdlen;
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memcpy( buffer, digest, buflen );
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m_free(context);
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return buflen;
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}
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int
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md_get_algo( MD_HANDLE a )
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{
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struct md_digest_list_s *r;
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if( (r=a->list) ) {
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if( r->next )
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log_error("WARNING: more than algorithm in md_get_algo()\n");
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return r->algo;
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}
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return 0;
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}
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/* Returns true if a given algo is in use in a md */
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int
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md_algo_present( MD_HANDLE a, int algo )
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{
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struct md_digest_list_s *r=a->list;
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while(r)
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{
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if(r->algo==algo)
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return 1;
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r=r->next;
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}
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return 0;
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}
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/****************
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* Return the length of the digest
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*/
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int
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md_digest_length( int algo )
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{
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struct md_digest_list_s *r;
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do {
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for(r = digest_list; r; r = r->next ) {
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if( r->algo == algo )
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return r->mdlen;
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}
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} while( !r && load_digest_module () );
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log_error("WARNING: no length for md algo %d\n", algo);
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return 0;
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}
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/* Hmmm: add a mode to enumerate the OIDs
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* to make g10/sig-check.c more portable */
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const byte *
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md_asn_oid( int algo, size_t *asnlen, size_t *mdlen )
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{
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struct md_digest_list_s *r;
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do {
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for(r = digest_list; r; r = r->next ) {
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if( r->algo == algo ) {
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if( asnlen )
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*asnlen = r->asnlen;
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if( mdlen )
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*mdlen = r->mdlen;
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return r->asnoid;
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}
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}
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} while( !r && load_digest_module () );
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log_bug("no asn for md algo %d\n", algo);
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return NULL;
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}
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void
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md_start_debug( MD_HANDLE md, const char *suffix )
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{
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static int idx=0;
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char buf[25];
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if( md->debug ) {
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log_debug("Oops: md debug already started\n");
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return;
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}
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idx++;
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sprintf(buf, "dbgmd-%05d" EXTSEP_S "%.10s", idx, suffix );
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md->debug = fopen(buf, "w");
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if( !md->debug )
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log_debug("md debug: can't open %s\n", buf );
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}
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void
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md_stop_debug( MD_HANDLE md )
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{
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if( md->debug ) {
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if( md->bufcount )
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md_write( md, NULL, 0 );
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fclose(md->debug);
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md->debug = NULL;
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}
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#ifdef HAVE_U64_TYPEDEF
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{ /* a kludge to pull in the __muldi3 for Solaris */
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volatile u32 a = (u32)(ulong)md;
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volatile u64 b = 42;
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volatile u64 c;
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c = a * b;
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}
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#endif
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}
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