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/* md.c - message digest dispatcher
* Copyright (C) 1998,1999 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
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "util.h"
#include "cipher.h"
#include "errors.h"
#include "dynload.h"
#include "rmd.h"
/****************
* This structure is used for the list of available algorithms
* and for the list of algorithms in MD_HANDLE.
*/
struct md_digest_list_s {
struct md_digest_list_s *next;
const char *name;
int algo;
byte *asnoid;
int asnlen;
int mdlen;
void (*init)( void *c );
void (*write)( void *c, byte *buf, size_t nbytes );
void (*final)( void *c );
byte *(*read)( void *c );
size_t contextsize; /* allocate this amount of context */
char context[1];
};
static struct md_digest_list_s *digest_list;
static struct md_digest_list_s *
new_list_item( int algo,
const char *(*get_info)( int, size_t*,byte**, int*, int*,
void (**)(void*),
void (**)(void*,byte*,size_t),
void (**)(void*),byte *(**)(void*)) )
{
struct md_digest_list_s *r;
r = m_alloc_clear( sizeof *r );
r->algo = algo,
r->name = (*get_info)( algo, &r->contextsize,
&r->asnoid, &r->asnlen, &r->mdlen,
&r->init, &r->write, &r->final, &r->read );
if( !r->name ) {
m_free(r);
r = NULL;
}
return r;
}
/****************
* Try to load the modules with the requeste algorithm
* and return true if new modules are available
* If req_alog is -1 try to load all digest algorithms.
*/
static int
load_digest_module( int req_algo )
{
static int initialized = 0;
static u32 checked_algos[256/32];
static int checked_all = 0;
struct md_digest_list_s *r;
void *context = NULL;
int algo;
int any = 0;
const char *(*get_info)( int, size_t*,byte**, int*, int*,
void (**)(void*),
void (**)(void*,byte*,size_t),
void (**)(void*),byte *(**)(void*));
if( !initialized ) {
cipher_modules_constructor();
initialized = 1;
}
algo = req_algo;
if( algo > 255 || !algo )
return 0; /* algorithm number too high (does not fit into out bitmap)*/
if( checked_all )
return 0; /* already called with -1 */
if( algo < 0 )
checked_all = 1;
else if( (checked_algos[algo/32] & (1 << (algo%32))) )
return 0; /* already checked and not found */
else
checked_algos[algo/32] |= (1 << (algo%32));
while( enum_gnupgext_digests( &context, &algo, &get_info ) ) {
if( req_algo != -1 && algo != req_algo )
continue;
for(r=digest_list; r; r = r->next )
if( r->algo == algo )
break;
if( r ) {
log_info("skipping digest %d: already loaded\n", algo );
continue;
}
r = new_list_item( algo, get_info );
if( ! r ) {
log_info("skipping digest %d: no name\n", algo );
continue;
}
/* put it into the list */
if( g10_opt_verbose > 1 )
log_info("loaded digest %d\n", algo);
r->next = digest_list;
digest_list = r;
any = 1;
if( req_algo != -1 )
break;
}
enum_gnupgext_digests( &context, NULL, NULL );
return any;
}
/****************
* Map a string to the digest algo
*/
int
string_to_digest_algo( const char *string )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next )
if( !stricmp( r->name, string ) )
return r->algo;
} while( !r && load_digest_module(-1) );
return 0;
}
/****************
* Map a digest algo to a string
*/
const char *
digest_algo_to_string( int algo )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next )
if( r->algo == algo )
return r->name;
} while( !r && load_digest_module( algo ) );
return NULL;
}
int
check_digest_algo( int algo )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next )
if( r->algo == algo )
return 0;
} while( !r && load_digest_module(algo) );
return G10ERR_DIGEST_ALGO;
}
/****************
* Open a message digest handle for use with algorithm ALGO.
* More algorithms may be added by md_enable(). The initial algorithm
* may be 0.
*/
MD_HANDLE
md_open( int algo, int secure )
{
MD_HANDLE hd;
int bufsize;
if( secure ) {
bufsize = 512 - sizeof( *hd );
hd = m_alloc_secure_clear( sizeof *hd + bufsize );
}
else {
bufsize = 1024 - sizeof( *hd );
hd = m_alloc_clear( sizeof *hd + bufsize );
}
hd->bufsize = bufsize+1; /* hd has already one byte allocated */
hd->secure = secure;
if( algo )
md_enable( hd, algo );
fast_random_poll();
return hd;
}
void
md_enable( MD_HANDLE h, int algo )
{
struct md_digest_list_s *r, *ac;
for( ac=h->list; ac; ac = ac->next )
if( ac->algo == algo )
return ; /* already enabled */
/* find the algorithm */
do {
for(r = digest_list; r; r = r->next )
if( r->algo == algo )
break;
} while( !r && load_digest_module( algo ) );
if( !r ) {
log_error("md_enable: algorithm %d not available\n", algo );
return;
}
/* and allocate a new list entry */
ac = h->secure? m_alloc_secure( sizeof *ac + r->contextsize )
: m_alloc( sizeof *ac + r->contextsize );
*ac = *r;
ac->next = h->list;
h->list = ac;
/* and init this instance */
(*ac->init)( &ac->context );
}
MD_HANDLE
md_copy( MD_HANDLE a )
{
MD_HANDLE b;
struct md_digest_list_s *ar, *br;
if( a->bufcount )
md_write( a, NULL, 0 );
b = a->secure ? m_alloc_secure( sizeof *b + a->bufsize - 1 )
: m_alloc( sizeof *b + a->bufsize - 1 );
memcpy( b, a, sizeof *a + a->bufsize - 1 );
b->list = NULL;
b->debug = NULL;
/* and now copy the complete list of algorithms */
/* I know that the copied list is reversed, but that doesn't matter */
for( ar=a->list; ar; ar = ar->next ) {
br = a->secure ? m_alloc_secure( sizeof *br + ar->contextsize )
: m_alloc( sizeof *br + ar->contextsize );
memcpy( br, ar, sizeof(*br) + ar->contextsize );
br->next = b->list;
b->list = br;
}
if( a->debug )
md_start_debug( b, "unknown" );
return b;
}
/****************
* Reset all contexts and discard any buffered stuff. This may be used
* instead of a md_close(); md_open().
*/
void
md_reset( MD_HANDLE a )
{
struct md_digest_list_s *r;
a->bufcount = 0;
for( r=a->list; r; r = r->next ) {
memset( r->context, 0, r->contextsize );
(*r->init)( &r->context );
}
}
void
md_close(MD_HANDLE a)
{
struct md_digest_list_s *r, *r2;
if( !a )
return;
if( a->debug )
md_stop_debug(a);
for(r=a->list; r; r = r2 ) {
r2 = r->next;
m_free(r);
}
m_free(a);
}
void
md_write( MD_HANDLE a, byte *inbuf, size_t inlen)
{
struct md_digest_list_s *r;
if( a->debug ) {
if( a->bufcount && fwrite(a->buffer, a->bufcount, 1, a->debug ) != 1 )
BUG();
if( inlen && fwrite(inbuf, inlen, 1, a->debug ) != 1 )
BUG();
}
for(r=a->list; r; r = r->next ) {
(*r->write)( &r->context, a->buffer, a->bufcount );
(*r->write)( &r->context, inbuf, inlen );
}
a->bufcount = 0;
}
void
md_final(MD_HANDLE a)
{
struct md_digest_list_s *r;
if( a->bufcount )
md_write( a, NULL, 0 );
for(r=a->list; r; r = r->next ) {
(*r->final)( &r->context );
}
}
/****************
* if ALGO is null get the digest for the used algo (which should be only one)
*/
byte *
md_read( MD_HANDLE a, int algo )
{
struct md_digest_list_s *r;
if( !algo ) { /* return the first algorithm */
if( (r=a->list) ) {
if( r->next )
log_debug("more than algorithm in md_read(0)\n");
return (*r->read)( &r->context );
}
}
else {
for(r=a->list; r; r = r->next )
if( r->algo == algo )
return (*r->read)( &r->context );
}
BUG();
return NULL;
}
/****************
* This function combines md_final and md_read but keeps the context
* intact. This function can be used to calculate intermediate
* digests. The digest is copied into buffer and the digestlength is
* returned. If buffer is NULL only the needed size for buffer is returned.
* buflen gives the max size of buffer. If the buffer is too shourt to
* hold the complete digest, the buffer is filled with as many bytes are
* possible and this value is returned.
*/
int
md_digest( MD_HANDLE a, int algo, byte *buffer, int buflen )
{
struct md_digest_list_s *r = NULL;
char *context;
char *digest;
if( a->bufcount )
md_write( a, NULL, 0 );
if( !algo ) { /* return digest for the first algorithm */
if( (r=a->list) && r->next )
log_debug("more than algorithm in md_digest(0)\n");
}
else {
for(r=a->list; r; r = r->next )
if( r->algo == algo )
break;
}
if( !r )
BUG();
if( !buffer )
return r->mdlen;
/* I don't want to change the interface, so I simply work on a copy
* the context (extra overhead - should be fixed)*/
context = a->secure ? m_alloc_secure( r->contextsize )
: m_alloc( r->contextsize );
memcpy( context, r->context, r->contextsize );
(*r->final)( context );
digest = (*r->read)( context );
if( buflen > r->mdlen )
buflen = r->mdlen;
memcpy( buffer, digest, buflen );
m_free(context);
return buflen;
}
int
md_get_algo( MD_HANDLE a )
{
struct md_digest_list_s *r;
if( (r=a->list) ) {
if( r->next )
log_error("WARNING: more than algorithm in md_get_algo()\n");
return r->algo;
}
return 0;
}
/****************
* Return the length of the digest
*/
int
md_digest_length( int algo )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next ) {
if( r->algo == algo )
return r->mdlen;
}
} while( !r && load_digest_module( algo ) );
log_error("WARNING: no length for md algo %d\n", algo);
return 0;
}
/* fixme: add a mode to enumerate the OIDs
* to make g10/sig-check.c more portable */
const byte *
md_asn_oid( int algo, size_t *asnlen, size_t *mdlen )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next ) {
if( r->algo == algo ) {
if( asnlen )
*asnlen = r->asnlen;
if( mdlen )
*mdlen = r->mdlen;
return r->asnoid;
}
}
} while( !r && load_digest_module( algo ) );
log_bug("no asn for md algo %d\n", algo);
return NULL;
}
void
md_start_debug( MD_HANDLE md, const char *suffix )
{
static int idx=0;
char buf[25];
if( md->debug ) {
log_debug("Oops: md debug already started\n");
return;
}
idx++;
sprintf(buf, "dbgmd-%05d.%.10s", idx, suffix );
md->debug = fopen(buf, "w");
if( !md->debug )
log_debug("md debug: can't open %s\n", buf );
}
void
md_stop_debug( MD_HANDLE md )
{
if( md->debug ) {
if( md->bufcount )
md_write( md, NULL, 0 );
fclose(md->debug);
md->debug = NULL;
}
#ifdef HAVE_U64_TYPEDEF
{ /* a kludge to pull in the __muldi3 for Solaris */
volatile u32 a = (u32)(ulong)md;
volatile u64 b = 42;
volatile u64 c;
c = a * b;
}
#endif
}

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