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/*
* Copyright (c) 2006 Atheme Development Group
* Rights to this code are as documented in doc/LICENSE.
*
* DH-BLOWFISH mechanism provider
*
*/
#include "atheme.h"
#ifdef HAVE_OPENSSL
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/blowfish.h>
#include <arpa/inet.h>
DECLARE_MODULE_V1
(
"saslserv/dh-blowfish", false, _modinit, _moddeinit,
PACKAGE_STRING,
"Atheme Development Group <http://www.atheme.org>"
);
mowgli_list_t *mechanisms;
mowgli_node_t *mnode;
static int mech_start(sasl_session_t *p, char **out, int *out_len);
static int mech_step(sasl_session_t *p, char *message, int len, char **out, int *out_len);
static void mech_finish(sasl_session_t *p);
sasl_mechanism_t mech = {"DH-BLOWFISH", &mech_start, &mech_step, &mech_finish};
void _modinit(module_t *m)
{
MODULE_USE_SYMBOL(mechanisms, "saslserv/main", "sasl_mechanisms");
mnode = mowgli_node_create();
mowgli_node_add(&mech, mnode, mechanisms);
}
void _moddeinit()
{
mowgli_node_delete(mnode, mechanisms);
mowgli_node_free(mnode);
}
static int mech_start(sasl_session_t *p, char **out, int *out_len)
{
DH *dh;
char *ptr;
if ((dh = DH_generate_parameters(256, 5, NULL, NULL)) == NULL)
return ASASL_FAIL;
if (!DH_generate_key(dh))
{
DH_free(dh);
return ASASL_FAIL;
}
/* Serialize p, g, and pub_key */
*out = malloc(BN_num_bytes(dh->p) + BN_num_bytes(dh->g) + BN_num_bytes(dh->pub_key) + 6);
*out_len = BN_num_bytes(dh->p) + BN_num_bytes(dh->g) + BN_num_bytes(dh->pub_key) + 6;
ptr = *out;
/* p */
*((unsigned int *)ptr) = htons(BN_num_bytes(dh->p));
BN_bn2bin(dh->p, (unsigned char *)ptr + 2);
ptr += 2 + BN_num_bytes(dh->p);
/* g */
*((unsigned int *)ptr) = htons(BN_num_bytes(dh->g));
BN_bn2bin(dh->g, (unsigned char *)ptr + 2);
ptr += 2 + BN_num_bytes(dh->g);
/* pub_key */
*((unsigned int *)ptr) = htons(BN_num_bytes(dh->pub_key));
BN_bn2bin(dh->pub_key, (unsigned char *)ptr + 2);
ptr += 2 + BN_num_bytes(dh->pub_key);
p->mechdata = dh;
return ASASL_MORE;
}
static int mech_step(sasl_session_t *p, char *message, int len, char **out, int *out_len)
{
DH *dh = NULL;
BF_KEY key;
BIGNUM *their_key = NULL;
myuser_t *mu;
char *ptr, *secret = NULL, *password = NULL;
int size, ret = ASASL_FAIL;
if (!p->mechdata)
return ASASL_FAIL;
dh = (DH*)p->mechdata;
/* Their pub_key */
if (len < 2)
goto end;
size = ntohs(*(unsigned int*)message);
message += 2;
len -= 2;
if (size > len)
goto end;
if ((their_key = BN_bin2bn((unsigned char *)message, size, NULL)) == NULL)
goto end;
message += size;
len -= size;
/* Username */
size = strlen(message);
if (size >= NICKLEN) /* our base64 routines null-terminate - how polite */
goto end;
p->username = strdup(message);
message += size + 1;
len -= size + 1;
if ((mu = myuser_find(p->username)) == NULL)
goto end;
/* AES-encrypted password remains */
/* Compute shared secret */
secret = (char*)malloc(DH_size(dh));
if ((size = DH_compute_key((unsigned char *)secret, their_key, dh)) == -1)
goto end;
/* Data must be multiple of block size, and let's be reasonable about size */
if (len == 0 || len % 8 || len > 128)
goto end;
/* Decrypt! */
BF_set_key(&key, size, (unsigned char *)secret);
ptr = password = (char*)malloc(len + 1);
password[len] = '\0';
while (len)
{
BF_ecb_encrypt((unsigned char *)message, (unsigned char *)ptr, &key, BF_DECRYPT);
message += 8;
ptr += 8;
len -= 8;
}
if (verify_password(mu, password))
ret = ASASL_DONE;
end:
if (their_key)
BN_free(their_key);
free(secret);
free(password);
return ret;
}
static void mech_finish(sasl_session_t *p)
{
if (p && p->mechdata)
{
DH_free((DH*)p->mechdata);
p->mechdata = NULL;
}
}
#endif /* HAVE_OPENSSL */
/* vim:cinoptions=>s,e0,n0,f0,{0,}0,^0,=s,ps,t0,c3,+s,(2s,us,)20,*30,gs,hs
* vim:ts=8
* vim:sw=8
* vim:noexpandtab
*/
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