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/*
Copyright (C) 2000 Stefan Westerfeld
stefan@space.twc.de
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include <config.h>
#include <sys/utsname.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>
#include <stdlib.h>
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#elif HAVE_SYS_TIME_H
# include <sys/time.h>
#else
# include <time.h>
#endif
#include "md5.h"
#include "md5auth.h"
#include "debug.h"
// MD5_BINARY_LEN is defined in md5.h
#define MD5_COOKIE_LEN (MD5_BINARY_LEN*2)
#define MD5_MANGLE_LEN (MD5_COOKIE_LEN*2)
struct random_info {
struct timeval tv;
int pid;
struct utsname un;
char dev_urandom[MD5_BINARY_LEN];
char seed[MD5_COOKIE_LEN+1];
int number;
};
static char md5_seed[MD5_COOKIE_LEN+1];
static char md5_cookie[MD5_COOKIE_LEN+1];
static int md5_init = 0;
static int md5_random_cookie_number = 0;
static char *md5_to_ascii_overwrite(char *md5)
{
char outascii[MD5_COOKIE_LEN+1];
char *result;
int i;
// convert to readable text
for(i = 0; i < MD5_BINARY_LEN; i++) {
sprintf(&outascii[i*2],"%02x",md5[i] & 0xff);
}
outascii[MD5_COOKIE_LEN] = 0;
result = strdup(outascii);
// try to zero out traces
memset(md5,0,MD5_BINARY_LEN);
memset(outascii,0,MD5_COOKIE_LEN);
// well, here it is
return result;
}
char *arts_md5_auth_mangle(const char *cookie)
{
char mangle[MD5_MANGLE_LEN+1];
char out[MD5_BINARY_LEN];
assert(md5_init);
// concat the two cookies and mangle them to a new one
strncpy(mangle,md5_cookie, MD5_COOKIE_LEN);
mangle[MD5_COOKIE_LEN] = 0;
strncat(mangle,cookie, MD5_COOKIE_LEN);
mangle[MD5_MANGLE_LEN] = 0;
arts_md5sum((unsigned char *)mangle,MD5_MANGLE_LEN,out);
// try to zero out traces
memset(mangle,0,MD5_MANGLE_LEN);
return md5_to_ascii_overwrite(out);
}
char *arts_md5_auth_mkcookie()
{
struct random_info r;
char out[MD5_BINARY_LEN];
int rndfd;
memset(&r,0,sizeof(struct random_info));
// collect some "random" system information
gettimeofday(&r.tv,0);
r.pid = getpid();
uname(&r.un);
// linux random device ; if that works, we have good random anyway, the
// above are just helpers for the case that it doesn't
rndfd = open("/dev/urandom",O_RDONLY);
if(rndfd != -1)
{
read(rndfd,r.dev_urandom,MD5_BINARY_LEN);
close(rndfd);
}
// ensure that two cookies that are requested very shortly after each
// other (so that it looks like "at the same time") won't be the same
r.number = ++md5_random_cookie_number;
// this is some seed from a file which is updated sometimes with a
// new "arts_md5_auth_mkcookie()" after initialization
strncpy(r.seed,md5_seed,MD5_COOKIE_LEN);
// build hash value of all information
arts_md5sum((unsigned char *)&r,sizeof(struct random_info),out);
// zero out traces and return
memset(&r,0,sizeof(struct random_info));
return md5_to_ascii_overwrite(out);
}
const char *arts_md5_auth_cookie()
{
assert(md5_init);
return md5_cookie;
}
static int md5_load_cookie(const char *filename, char *cookie)
{
int fd = open(filename,O_RDONLY);
int i;
if(fd != -1) {
struct stat st;
for(i=0;i<5;i++) {
fstat(fd,&st);
if(st.st_size == MD5_COOKIE_LEN) {
lseek(fd, 0, SEEK_SET);
if(read(fd,cookie,MD5_COOKIE_LEN) == MD5_COOKIE_LEN)
{
cookie[MD5_COOKIE_LEN] = 0;
close(fd);
return 1;
}
}
arts_warning("MCOP: "
"authority file has wrong size (just being written?)");
sleep(1);
}
}
return 0;
}
void arts_md5_auth_init_seed(const char *seedname)
{
// don't care if it works - no harm is being done if it doesn't
md5_load_cookie(seedname,md5_seed);
/*
* maxage ensures that not everybody will try to update the seed
* at the same time, while it will take at most 5 hours between
* updates (if there are any initialization calls)
*/
struct stat st;
int maxage = 300 + (getpid() & 0xfff)*4;
int lstat_result = lstat(seedname,&st);
if(lstat_result != 0 || (time(0) - st.st_mtime) > maxage)
{
int fd = open(seedname,O_TRUNC|O_CREAT|O_WRONLY,S_IRUSR|S_IWUSR);
if(fd != -1) {
char *cookie = arts_md5_auth_mkcookie();
write(fd,cookie,strlen(cookie));
memset(cookie,0,strlen(cookie));
free(cookie);
close(fd);
}
}
}
bool arts_md5_auth_set_cookie(const char *cookie)
{
if(strlen(cookie) != MD5_COOKIE_LEN)
return false;
strncpy(md5_cookie,cookie,MD5_COOKIE_LEN);
md5_cookie[MD5_COOKIE_LEN] = 0;
md5_init = 1;
return true;
}
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