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|
/* Copyright 2001,2002 Roger Dingledine, Matej Pfajfar. */
/* See LICENSE for licensing information */
/* $Id$ */
#include "or.h"
extern int global_role; /* from main.c */
/********* START VARIABLES **********/
tracked_onion_t *tracked_onions = NULL; /* linked list of tracked onions */
tracked_onion_t *last_tracked_onion = NULL;
/********* END VARIABLES ************/
int decide_aci_type(uint32_t local_addr, uint16_t local_port,
uint32_t remote_addr, uint16_t remote_port) {
if(local_addr > remote_addr)
return ACI_TYPE_HIGHER;
if(local_addr < remote_addr)
return ACI_TYPE_LOWER;
if(local_port > remote_port)
return ACI_TYPE_HIGHER;
/* else */
return ACI_TYPE_LOWER;
}
int process_onion(circuit_t *circ, connection_t *conn) {
aci_t aci_type;
if(!decrypt_onion((onion_layer_t *)circ->onion,circ->onionlen,conn->prkey)) {
log(LOG_DEBUG,"command_process_create_cell(): decrypt_onion() failed, closing circuit.");
return -1;
}
log(LOG_DEBUG,"command_process_create_cell(): Onion decrypted.");
/* check freshness */
if (((onion_layer_t *)circ->onion)->expire < time(NULL)) /* expired onion */
{
log(LOG_NOTICE,"I have just received an expired onion. This could be a replay attack.");
return -1;
}
aci_type = decide_aci_type(conn->local.sin_addr.s_addr, ntohs(conn->local.sin_port),
((onion_layer_t *)circ->onion)->addr,((onion_layer_t *)circ->onion)->port);
if(circuit_init(circ, aci_type) < 0) {
log(LOG_ERR,"process_onion(): init_circuit() failed.");
return -1;
}
/* check for replay */
if(id_tracked_onion(circ->onion, circ->onionlen, tracked_onions)) {
log(LOG_NOTICE,"process_onion(): I have just received a replayed onion. This could be a replay attack.");
return -1;
}
/* track the new onion */
if(!new_tracked_onion(circ->onion,circ->onionlen, &tracked_onions, &last_tracked_onion)) {
log(LOG_DEBUG,"process_onion(): Onion tracking failed. Will ignore.");
}
return 0;
}
/* uses a weighted coin with weight cw to choose a route length */
int chooselen(double cw)
{
int len = 2;
int retval = 0;
unsigned char coin;
if ((cw < 0) || (cw >= 1)) /* invalid parameter */
return -1;
while(1)
{
retval = crypto_pseudo_rand(1, &coin);
if (retval)
return -1;
if (coin > cw*255) /* don't extend */
break;
else
len++;
}
return len;
}
/* returns an array of pointers to routent that define a new route through the OR network
* int cw is the coin weight to use when choosing the route
* order of routers is from last to first
*/
unsigned int *new_route(double cw, routerinfo_t **rarray, int rarray_len, int *routelen)
{
int i, j;
int num_acceptable_routers = 0;
unsigned int *route = NULL;
unsigned int oldchoice, choice;
assert((cw >= 0) && (cw < 1) && (rarray) && (routelen) ); /* valid parameters */
*routelen = chooselen(cw);
if (*routelen == -1) {
log(LOG_ERR,"Choosing route length failed.");
return NULL;
}
log(LOG_DEBUG,"new_route(): Chosen route length %d.",*routelen);
for(i=0;i<rarray_len;i++) {
log(LOG_DEBUG,"Contemplating whether router %d is a new option...",i);
if( (global_role & ROLE_OR_CONNECT_ALL) &&
!connection_exact_get_by_addr_port(rarray[i]->addr, rarray[i]->or_port)) {
log(LOG_DEBUG,"Nope, %d is not connected.",i);
goto next_i_loop;
}
for(j=0;j<i;j++) {
if(!pkey_cmp(rarray[i]->pkey, rarray[j]->pkey)) {
/* these guys are twins. so we've already counted him. */
log(LOG_DEBUG,"Nope, %d is a twin of %d.",i,j);
goto next_i_loop;
}
}
num_acceptable_routers++;
log(LOG_DEBUG,"I like %d. num_acceptable_routers now %d.",i, num_acceptable_routers);
next_i_loop:
; /* our compiler may need an explicit statement after the label */
}
if(num_acceptable_routers < *routelen) {
log(LOG_DEBUG,"new_route(): Cutting routelen from %d to %d.",*routelen, num_acceptable_routers);
*routelen = num_acceptable_routers;
}
if(*routelen < 1) {
log(LOG_ERR,"new_route(): Didn't find any acceptable routers. Failing.");
return NULL;
}
/* allocate memory for the new route */
route = (unsigned int *)malloc(*routelen * sizeof(unsigned int));
if (!route) {
log(LOG_ERR,"Memory allocation failed.");
return NULL;
}
oldchoice = rarray_len;
for(i=0;i<*routelen;i++) {
log(LOG_DEBUG,"new_route(): Choosing hop %u.",i);
if(crypto_pseudo_rand(sizeof(unsigned int),(unsigned char *)&choice)) {
free((void *)route);
return NULL;
}
choice = choice % (rarray_len);
log(LOG_DEBUG,"new_route(): Contemplating router %u.",choice);
if(choice == oldchoice ||
(oldchoice < rarray_len && !pkey_cmp(rarray[choice]->pkey, rarray[oldchoice]->pkey)) ||
((global_role & ROLE_OR_CONNECT_ALL) && !connection_twin_get_by_addr_port(rarray[choice]->addr, rarray[choice]->or_port))) {
/* Same router as last choice, or router twin,
* or no routers with that key are connected to us.
* Try again. */
log(LOG_DEBUG,"new_route(): Picked a router %d that won't work as next hop.",choice);
i--;
continue;
}
log(LOG_DEBUG,"new_route(): Chosen router %u for hop %u.",choice,i);
oldchoice = choice;
route[i] = choice;
}
return route;
}
/* creates a new onion from route, stores it and its length into buf and len respectively */
unsigned char *create_onion(routerinfo_t **rarray, int rarray_len, unsigned int *route, int routelen, int *len, crypt_path_t **cpath)
{
int i,j;
int retval = 0;
onion_layer_t *layer = NULL;
crypt_path_t *hop = NULL;
unsigned char *retbuf = NULL;
unsigned char *buf;
routerinfo_t *router;
unsigned char iv[16];
assert(rarray && route && len && routelen);
/* calculate the size of the onion */
*len = routelen * 28 + 100; /* 28 bytes per layer + 100 bytes padding for the innermost layer */
log(LOG_DEBUG,"create_onion() : Size of the onion is %u.",*len);
/* allocate memory for the onion */
buf = (unsigned char *)malloc(*len);
if (!buf)
{
log(LOG_ERR,"Error allocating memory.");
return NULL;
}
log(LOG_DEBUG,"create_onion() : Allocated memory for the onion.");
for (retval=0; retval<routelen;retval++)
{
log(LOG_DEBUG,"create_onion() : %u : %s:%u, %u/%u",routelen-retval,inet_ntoa(*((struct in_addr *)&((rarray[route[retval]])->addr))),(rarray[route[retval]])->or_port,(rarray[route[retval]])->pkey,crypto_pk_keysize((rarray[route[retval]])->pkey));
}
layer = (onion_layer_t *)(buf + *len - 128); /* pointer to innermost layer */
/* create the onion layer by layer, starting with the innermost */
for (i=0;i<routelen;i++)
{
router = rarray[route[i]];
log(LOG_DEBUG,"create_onion() : %u",router);
log(LOG_DEBUG,"create_onion() : This router is %s:%u",inet_ntoa(*((struct in_addr *)&router->addr)),router->or_port);
log(LOG_DEBUG,"create_onion() : Key pointer = %u.",router->pkey);
log(LOG_DEBUG,"create_onion() : Key size = %u.",crypto_pk_keysize(router->pkey));
/* 0 bit */
layer->zero = 0;
/* version */
layer->version = VERSION;
/* Back F + Forw F both use DES OFB*/
layer->backf = ONION_DEFAULT_CIPHER;
layer->forwf = ONION_DEFAULT_CIPHER;
/* Dest Port */
if (i) /* not last hop */
layer->port = rarray[route[i-1]]->or_port;
else
layer->port = 0;
/* Dest Addr */
if (i) /* not last hop */
layer->addr = rarray[route[i-1]]->addr;
else
layer->addr = 0;
/* Expiration Time */
layer->expire = time(NULL) + 3600; /* NOW + 1 hour */
/* Key Seed Material */
retval = crypto_rand(16, layer->keyseed);
if (retval) /* error */
{
log(LOG_ERR,"Error generating random data.");
free((void *)buf);
if (cpath)
{
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
}
return NULL;
}
log(LOG_DEBUG,"create_onion() : Onion layer %u built : %u, %u, %u, %s, %u.",i+1,layer->zero,layer->backf,layer->forwf,inet_ntoa(*((struct in_addr *)&layer->addr)),layer->port);
/* build up the crypt_path */
if (cpath)
{
cpath[i] = (crypt_path_t *)malloc(sizeof(crypt_path_t));
if (!cpath[i])
{
log(LOG_ERR,"Error allocating memory.");
free((void *)buf);
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
}
log(LOG_DEBUG,"create_onion() : Building hop %u of crypt path.",i+1);
hop = cpath[i];
/* set crypto functions */
hop->backf = layer->backf;
hop->forwf = layer->forwf;
/* calculate keys */
crypto_SHA_digest(layer->keyseed,16,hop->digest3);
log(LOG_DEBUG,"create_onion() : First SHA pass performed.");
crypto_SHA_digest(hop->digest3,20,hop->digest2);
log(LOG_DEBUG,"create_onion() : Second SHA pass performed.");
crypto_SHA_digest(hop->digest2,20,hop->digest3);
log(LOG_DEBUG,"create_onion() : Third SHA pass performed.");
log(LOG_DEBUG,"create_onion() : Keys generated.");
/* set IV to zero */
memset((void *)iv,0,16);
/* initialize cipher engines */
switch(layer->forwf)
{
case ONION_CIPHER_DES :
hop->f_crypto = crypto_new_cipher_env(CRYPTO_CIPHER_DES);
break;
case ONION_CIPHER_RC4 :
hop->f_crypto = crypto_new_cipher_env(CRYPTO_CIPHER_RC4);
break;
case ONION_CIPHER_IDENTITY :
hop->f_crypto = crypto_new_cipher_env(CRYPTO_CIPHER_IDENTITY);
break;
}
if (!hop->f_crypto) /* cipher initialization failed */
{
log(LOG_ERR,"Could not create a crypto environment.");
free((void *)buf);
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
return NULL;
}
/* set the key and IV */
if (crypto_cipher_set_key(hop->f_crypto, hop->digest3) ||
crypto_cipher_set_iv(hop->f_crypto, iv)) {
log(LOG_ERR,"Could not initialize the crypto engine.");
free((void *)buf);
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
return NULL;
}
switch(layer->backf)
{
case ONION_CIPHER_DES :
hop->b_crypto = crypto_new_cipher_env(CRYPTO_CIPHER_DES);
break;
case ONION_CIPHER_RC4 :
hop->b_crypto = crypto_new_cipher_env(CRYPTO_CIPHER_RC4);
break;
case ONION_CIPHER_IDENTITY :
hop->b_crypto = crypto_new_cipher_env(CRYPTO_CIPHER_IDENTITY);
break;
}
if (!hop->b_crypto) /* cipher initialization failed */
{
log(LOG_ERR,"Could not create a crypto environment.");
free((void *)buf);
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
return NULL;
}
/* set the key and IV */
if (crypto_cipher_set_key(hop->b_crypto, hop->digest2) ||
crypto_cipher_set_iv(hop->b_crypto, iv)) {
log(LOG_ERR,"Could not initialize the crypto engine.");
free((void *)buf);
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
return NULL;
}
/* initialize */
if (crypto_cipher_encrypt_init_cipher(hop->f_crypto) || crypto_cipher_decrypt_init_cipher(hop->b_crypto)) {
log(LOG_ERR,"Could not initialize the crypto engine.");
free((void *)buf);
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
return NULL;
}
log(LOG_DEBUG,"create_onion() : Built corresponding crypt path hop.");
}
/* padding if this is the innermost layer */
if (!i)
{
retval=crypto_pseudo_rand(100, (unsigned char *)layer + 28);
if (retval) /* error */
{
log(LOG_ERR,"Error generating pseudo-random data.");
free((void *)buf);
if (cpath)
{
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
}
return NULL;
}
log(LOG_DEBUG,"create_onion() : This is the innermost layer. Adding 100 bytes of padding.");
}
/* encrypt */
retbuf = encrypt_onion(layer,128+(i*28),router->pkey);
if (!retbuf)
{
log(LOG_ERR,"Error encrypting onion layer.");
free((void *)buf);
if (cpath)
{
for (j=0;j<i;j++) {
if (cpath[i]->f_crypto)
crypto_free_cipher_env(cpath[i]->f_crypto);
if (cpath[i]->b_crypto)
crypto_free_cipher_env(cpath[i]->b_crypto);
free((void *)cpath[i]);
}
}
return NULL;
}
log(LOG_DEBUG,"create_onion() : Encrypted layer.");
/* calculate pointer to next layer */
layer = (onion_layer_t *)(buf + (routelen-i-2)*sizeof(onion_layer_t));
}
return buf;
}
/* encrypts 128 bytes of the onion with the specified public key, the rest with
* DES OFB with the key as defined in the outter layer */
unsigned char *encrypt_onion(onion_layer_t *onion, uint32_t onionlen, crypto_pk_env_t *pkey)
{
unsigned char *tmpbuf = NULL; /* temporary buffer for crypto operations */
unsigned char digest[20]; /* stores SHA1 output - 160 bits */
unsigned char iv[8];
int retval = 0;
crypto_cipher_env_t *crypt_env; /* crypto environment */
if ( (onion) && (pkey) ) /* valid parameters */
{
memset((void *)iv,0,8);
log(LOG_DEBUG,"Onion layer : %u, %u, %u, %s, %u.",onion->zero,onion->backf,onion->forwf,inet_ntoa(*((struct in_addr *)&onion->addr)),onion->port);
/* allocate space for tmpbuf */
tmpbuf = (unsigned char *)malloc(onionlen);
if (!tmpbuf)
{
log(LOG_ERR,"Could not allocate memory.");
return NULL;
}
log(LOG_DEBUG,"encrypt_onion() : allocated %u bytes of memory for the encrypted onion (at %u).",onionlen,tmpbuf);
/* get key1 = SHA1(KeySeed) */
if (crypto_SHA_digest(((onion_layer_t *)onion)->keyseed,16,digest))
{
log(LOG_ERR,"Error computing SHA1 digest.");
free((void *)tmpbuf);
return NULL;
}
log(LOG_DEBUG,"encrypt_onion() : Computed DES key.");
log(LOG_DEBUG,"encrypt_onion() : Trying to RSA encrypt.");
/* encrypt 128 bytes with RSA *pkey */
retval = crypto_pk_public_encrypt(pkey, (unsigned char *)onion, 128, tmpbuf, RSA_NO_PADDING);
if (retval == -1)
{
log(LOG_ERR,"Error RSA-encrypting data :%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
log(LOG_DEBUG,"encrypt_onion() : RSA encrypted first 128 bytes of the onion.");
/* now encrypt the rest with DES OFB */
crypt_env = crypto_new_cipher_env(CRYPTO_CIPHER_DES);
if (!crypt_env)
{
log(LOG_ERR,"Error creating the crypto environment.");
free((void *)tmpbuf);
return NULL;
}
if (crypto_cipher_set_key(crypt_env, digest)) /* error */
{
log(LOG_ERR,"Error initializing DES engine:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
if (crypto_cipher_set_iv(crypt_env, iv))
{
log(LOG_ERR,"Error initializing DES engine:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
if (crypto_cipher_encrypt_init_cipher(crypt_env)) {
log(LOG_ERR,"Error initializing DES engine:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
retval = crypto_cipher_encrypt(crypt_env,(unsigned char *)onion+128, onionlen-128, (unsigned char *)tmpbuf+128);
if (retval) /* error */
{
log(LOG_ERR,"Error performing DES encryption:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
log(LOG_DEBUG,"encrypt_onion() : DES OFB encrypted the rest of the onion.");
crypto_free_cipher_env(crypt_env);
/* now copy tmpbuf to onion */
memcpy((void *)onion,(void *)tmpbuf,onionlen);
log(LOG_DEBUG,"encrypt_onion() : Copied cipher to original onion buffer.");
free((void *)tmpbuf);
return (unsigned char *)onion;
} /* valid parameters */
else
return NULL;
}
/* decrypts the first 128 bytes using RSA and prkey, decrypts the rest with DES OFB with key1 */
unsigned char *decrypt_onion(onion_layer_t *onion, uint32_t onionlen, crypto_pk_env_t *prkey)
{
void *tmpbuf = NULL; /* temporary buffer for crypto operations */
unsigned char digest[20]; /* stores SHA1 output - 160 bits */
unsigned char iv[8];
int retval = 0;
crypto_cipher_env_t *crypt_env; /* crypto environment */
if ( (onion) && (prkey) ) /* valid parameters */
{
memset((void *)iv,0,8);
/* allocate space for tmpbuf */
tmpbuf = malloc(onionlen);
if (!tmpbuf)
{
log(LOG_ERR,"Could not allocate memory.");
return NULL;
}
log(LOG_DEBUG,"decrypt_onion() : Allocated memory for the temporary buffer.");
/* decrypt 128 bytes with RSA *prkey */
retval = crypto_pk_private_decrypt(prkey, (unsigned char*)onion, 128, (unsigned char *)tmpbuf, RSA_NO_PADDING);
if (retval == -1)
{
log(LOG_ERR,"Error RSA-decrypting data :%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
log(LOG_DEBUG,"decrypt_onion() : RSA decryption complete.");
/* get key1 = SHA1(KeySeed) */
retval = crypto_SHA_digest(((onion_layer_t *)tmpbuf)->keyseed,16,digest);
if (retval)
{
log(LOG_ERR,"Error computing SHA1 digest.");
free((void *)tmpbuf);
return NULL;
}
log(LOG_DEBUG,"decrypt_onion() : Computed DES key.");
/* now decrypt the rest with DES OFB */
crypt_env = crypto_new_cipher_env(CRYPTO_CIPHER_DES);
if (!crypt_env)
{
log(LOG_ERR,"Error creating the crypto environment.");
free((void *)tmpbuf);
return NULL;
}
if (crypto_cipher_set_key(crypt_env, digest)) /* error */
{
log(LOG_ERR,"Error initializing DES engine:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
if (crypto_cipher_set_iv(crypt_env, iv))
{
log(LOG_ERR,"Error initializing DES engine:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
if (crypto_cipher_decrypt_init_cipher(crypt_env)) {
log(LOG_ERR,"Error initializing DES engine:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
retval = crypto_cipher_decrypt(crypt_env,(unsigned char *)onion+128, onionlen-128,(unsigned char *)tmpbuf+128);
if (retval) /* error */
{
log(LOG_ERR,"Error performing DES decryption:%s",crypto_perror());
free((void *)tmpbuf);
return NULL;
}
crypto_free_cipher_env(crypt_env);
log(LOG_DEBUG,"decrypt_onion() : DES decryption complete.");
/* now copy tmpbuf to onion */
memcpy((void *)onion,(void *)tmpbuf,onionlen);
free((void *)tmpbuf);
return (unsigned char *)onion;
} /* valid parameters */
else
return NULL;
}
/* delete first n bytes of the onion and pads the end with n bytes of random data */
void pad_onion(unsigned char *onion, uint32_t onionlen, int n)
{
if (onion) /* valid parameter */
{
memmove((void *)onion,(void *)(onion+n),onionlen-n);
crypto_pseudo_rand(n, onion+onionlen-n);
}
}
/* create a new tracked_onion entry */
tracked_onion_t *new_tracked_onion(unsigned char *onion, uint32_t onionlen, tracked_onion_t **tracked_onions, tracked_onion_t **last_tracked_onion)
{
tracked_onion_t *to = NULL;
if (!onion || !tracked_onions || !last_tracked_onion) /* invalid parameters */
return NULL;
to = (tracked_onion_t *)malloc(sizeof(tracked_onion_t));
if (!to)
return NULL;
to->expire = ((onion_layer_t *)onion)->expire; /* set the expiration date */
/* compute the SHA digest */
if (crypto_SHA_digest(onion, onionlen, to->digest))
{
log(LOG_DEBUG,"new_tracked_onion() : Failed to compute a SHA1 digest of the onion.");
free((void *)to);
return NULL;
}
to->next = NULL;
if (!*tracked_onions)
{
to->prev = NULL;
*tracked_onions = to;
}
else
{
to->prev = (void *)*last_tracked_onion;
(*last_tracked_onion)->next = (void *)to;
}
*last_tracked_onion = to;
return to;
}
/* delete a tracked onion entry */
void remove_tracked_onion(tracked_onion_t *to, tracked_onion_t **tracked_onions, tracked_onion_t **last_tracked_onion)
{
if (!*tracked_onions || !*last_tracked_onion || !to)
return;
if (to->prev)
((tracked_onion_t *)to->prev)->next = to->next;
if (to->next)
((tracked_onion_t *)to->next)->prev = to->prev;
if (to == *tracked_onions)
*tracked_onions = (tracked_onion_t *)to->next;
if (to == *last_tracked_onion)
*last_tracked_onion = (tracked_onion_t *)to->prev;
free((void *)to);
return;
}
/* find a tracked onion in the linked list of tracked onions */
tracked_onion_t *id_tracked_onion(unsigned char *onion, uint32_t onionlen, tracked_onion_t *tracked_onions)
{
tracked_onion_t *to = tracked_onions;
unsigned char digest[20];
/* compute the SHA digest of the onion */
crypto_SHA_digest(onion,onionlen, digest);
while(to)
{
if (!memcmp((void *)digest, (void *)to->digest, 20))
return to;
to = (tracked_onion_t *)to->next;
}
return NULL;
}
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