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/*
* NetCosm - a MUD server
* Copyright (C) 2016 Franklin Wei
*
* This program 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.
*
* This program 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 "globals.h"
#include "auth.h"
#include "client.h"
#include "userdb.h"
static bool valid_login_name(const char *name);
/* returns a pointer to a malloc-allocated buffer containing the salted hex hash of pass */
/* salt should point to a buffer containing SALT_LEN random characters */
/* pass must be null-terminated */
static char *hash_pass_hex(const char *pass, const char *salt)
{
size_t pass_len = strlen(pass);
unsigned char *salted = malloc(pass_len + SALT_LEN + 1);
memcpy(salted, salt, SALT_LEN);
memcpy(salted + SALT_LEN, pass, pass_len);
salted[pass_len + SALT_LEN] = '\0';
unsigned char hash[AUTH_HASHLEN];
SHA512(salted, pass_len + SALT_LEN, hash);
unsigned char tmp[AUTH_HASHLEN];
/* now hash the hash a million times to slow things down */
for(int i = 0; i < (HASH_ITERS / 2) - 1; ++i)
{
AUTH_HASHFUNC(hash, AUTH_HASHLEN, tmp);
AUTH_HASHFUNC(tmp, AUTH_HASHLEN, hash);
}
memset(tmp, 0, sizeof(tmp));
memset(salted, 0, pass_len + SALT_LEN + 1);
free(salted);
/* convert to hex */
char *hex = malloc(AUTH_HASHLEN * 2 + 1);
char *ptr = hex;
for(unsigned int i = 0; i < AUTH_HASHLEN; ++i, ptr += 2)
snprintf(ptr, 3, "%02x", hash[i]);
hex[AUTH_HASHLEN * 2] = '\0';
return hex;
}
static void add_user_internal(const char *name, const char *pass, int authlevel)
{
char salt[SALT_LEN + 1];
for(int i = 0; i < SALT_LEN; ++i)
{
salt[i] = 'A' + rand()%26;
}
salt[SALT_LEN] = '\0';
char *hexhash = hash_pass_hex(pass, salt);
/* doesn't need to be malloc'd */
struct userdata_t userdata;
memset(&userdata, 0, sizeof(userdata));
strncpy(userdata.username, name, sizeof(userdata.username));
memcpy(userdata.passhash, hexhash, sizeof(userdata.passhash));
free(hexhash);
userdata.priv = authlevel;
userdata.last_login = time(0);
memcpy(userdata.salt, salt, sizeof(salt));
userdb_request_add(&userdata);
}
bool auth_user_del(const char *user2)
{
char *user = strdup(user2);
remove_cruft(user);
if(valid_login_name(user))
return userdb_request_remove(user);
else
{
free(user);
return false;
}
}
bool auth_user_add(const char *user2, const char *pass2, int level)
{
char *user = strdup(user2);
remove_cruft(user);
char *pass = strdup(pass2);
remove_cruft(pass);
debugf("Add user '%s'\n", user);
if(!valid_login_name(user))
{
free(user);
free(pass);
return false;
}
add_user_internal(user, pass, level);
free(user);
memset(pass, 0, strlen(pass));
free(pass);
return true;
}
static bool valid_login_name(const char *name)
{
size_t len = 0;
while(*name)
{
char c = *name++;
++len;
if(len > MAX_NAME_LEN)
return false;
if(!(isalpha(c) || isdigit(c)))
return false;
}
return true;
}
void first_run_setup(void)
{
debugf("Welcome to NetCosm!\n");
debugf("Please set up the administrator account now.\n");
char *admin_name;
size_t len = 0;
do {
admin_name = NULL;
debugf("Admin account name: ");
fflush(stdout);
getline(&admin_name, &len, stdin);
remove_cruft(admin_name);
} while(!valid_login_name(admin_name));
debugf("Admin password (_DO_NOT_ USE A VALUABLE PASSWORD): ");
fflush(stdout);
char *admin_pass = NULL;
len = 0;
getline(&admin_pass, &len, stdin);
remove_cruft(admin_pass);
if(!auth_user_add(admin_name, admin_pass, PRIV_ADMIN))
error("Unknown error");
/* zero the memory */
memset(admin_name, 0, strlen(admin_name));
memset(admin_pass, 0, strlen(admin_pass));
free(admin_name);
free(admin_pass);
}
struct userdata_t *auth_check(const char *name2, const char *pass2)
{
/* get our own copy to remove newlines */
char *name = strdup(name2);
char *pass = strdup(pass2);
remove_cruft(name);
remove_cruft(pass);
/* find it in the user list */
struct userdata_t *data = userdb_request_lookup(name);
free(name);
char *salt = data->salt, *hash = data->passhash;
if(data)
{
debugf("auth module: user %s found\n", name2);
/* hashes are in lowercase hex to avoid the Trucha bug
* but still allow comparison with strcmp() */
char *new_hash_hex = hash_pass_hex(pass, salt);
bool success = true;
/* constant-time comparison to hopefully prevent a timing attack */
for(int i = 0; i < AUTH_HASHLEN; ++i)
{
if(new_hash_hex[i] != hash[i])
success = false;
}
free(new_hash_hex);
if(success)
{
memset(pass, 0, strlen(pass));
free(pass);
return data;
}
}
debugf("auth failure for user %s\n", name2);
memset(pass, 0, strlen(pass));
free(pass);
/* failure */
sleep(2);
return NULL;
}
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