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use a rbtree for replay detection, rather than linear search

Browse Source 
when we had lots of new onions coming in, we were using 40% of
our time searching through the tracked_onions linked list.


svn:r150
This commit is contained in:
Roger Dingledine 2002-12-31 15:04:14 +00:00
parent 0b717a3e74
commit 9d3e80a589
4 changed files with 89 additions and 118 deletions
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2
src/or/Makefile.am
View File

@ -15,6 +15,6 @@ test_config_SOURCES = test_config.c
test_config_LDADD = config.o -L../common -lor
noinst_HEADERS = or.h
noinst_HEADERS = or.h tree.h

30
src/or/main.c
View File

@ -376,31 +376,16 @@ int prepare_for_poll(int *timeout) {
for(i=0;i<nfds;i++)
check_conn_marked(i);
#if 0
/* check if we need to refill buckets or zero out any per-second stats */
for(i=0;i<nfds;i++) {
if(connection_receiver_bucket_should_increase(connection_array[i]) ||
connection_array[i]->onions_handled_this_second) {
need_to_wake_soon = 1;
break;
if(now.tv_sec > current_second) { /* the second has already rolled over! */
for(i=0;i<nfds;i++) {
connection_increment_receiver_bucket(connection_array[i]);
connection_array[i]->onions_handled_this_second = 0;
}
current_second = now.tv_sec; /* remember which second it is, for next time */
}
#endif
// if(need_to_wake_soon) {
if(now.tv_sec > current_second) { /* the second has already rolled over! */
// log(LOG_DEBUG,"prepare_for_poll(): The second has rolled over, immediately refilling.");
for(i=0;i<nfds;i++) {
connection_increment_receiver_bucket(connection_array[i]);
connection_array[i]->onions_handled_this_second = 0;
}
current_second = now.tv_sec; /* remember which second it is, for next time */
}
// } else {
/* this timeout is definitely sooner than any of the above ones */
*timeout = 1000 - (now.tv_usec / 1000); /* how many milliseconds til the next second? */
// }
// }
/* this timeout is definitely sooner than any of the above ones */
*timeout = 1000 - (now.tv_usec / 1000); /* how many milliseconds til the next second? */
if(options.LinkPadding) {
/* now check which conn wants to speak soonest */
@ -668,6 +653,7 @@ int main(int argc, char *argv[]) {
global_role = options.Role; /* assign global_role from options. FIXME: remove from global namespace later. */
crypto_global_init();
init_tracked_tree(); /* initialize the replay detection tree */
retval = do_main_loop();
crypto_global_cleanup();

152
src/or/onion.c
View File

@ -7,13 +7,6 @@
extern int global_role; /* from main.c */
extern or_options_t options; /* command-line and config-file options */
/********* START VARIABLES **********/
static tracked_onion_t *tracked_onions = NULL; /* linked list of tracked onions */
static tracked_onion_t *last_tracked_onion = NULL;
/********* END VARIABLES ************/
static int onion_process(circuit_t *circ);
static int onion_deliver_to_conn(aci_t aci, unsigned char *onion, uint32_t onionlen, connection_t *conn);
@ -255,17 +248,12 @@ static int onion_process(circuit_t *circ) {
return -1;
}
/* check for replay */
if(find_tracked_onion(circ->onion, circ->onionlen, tracked_onions)) {
/* check for replay. at the same time, add it to the pile of tracked onions. */
if(find_tracked_onion(circ->onion, circ->onionlen)) {
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(add_tracked_onion(circ->onion,circ->onionlen, &tracked_onions, &last_tracked_onion) < 0) {
log(LOG_DEBUG,"process_onion(): Onion tracking failed. Will ignore.");
}
/* now we must send create cells to the next router */
if(circ->n_addr && circ->n_port) {
n_conn = connection_twin_get_by_addr_port(circ->n_addr,circ->n_port);
@ -739,75 +727,85 @@ void pad_onion(unsigned char *onion, uint32_t onionlen, int n)
crypto_pseudo_rand(n, onion+onionlen-n);
}
/* create a new tracked_onion entry */
int add_tracked_onion(unsigned char *onion, uint32_t onionlen, tracked_onion_t **tracked_onions, tracked_onion_t **last_tracked_onion)
{
tracked_onion_t *to = NULL;
assert(onion && tracked_onions && last_tracked_onion);
to = (tracked_onion_t *)malloc(sizeof(tracked_onion_t));
if (!to)
return -1;
to->expire = ntohl(*(uint32_t *)(onion+8)); /* 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.");
/* red black tree using Niels' tree.h. I used
http://www.openbsd.org/cgi-bin/cvsweb/src/regress/sys/sys/tree/rb/rb-test.c?rev=1.2&content-type=text/x-cvsweb-markup
as my guide */
#include "tree.h"
struct tracked_onion {
RB_ENTRY(tracked_onion) node;
uint32_t expire;
char digest[20]; /* SHA digest of the onion */
struct tracked_onion *next;
};
RB_HEAD(tracked_tree, tracked_onion) tracked_root;
int compare_tracked_onions(struct tracked_onion *a, struct tracked_onion *b) {
return memcmp(a->digest, b->digest, 20);
}
RB_PROTOTYPE(tracked_tree, tracked_onion, node, compare_tracked_onions);
RB_GENERATE(tracked_tree, tracked_onion, node, compare_tracked_onions);
void init_tracked_tree(void) {
RB_INIT(&tracked_root);
}
/* see if this onion has been seen before. if so, return 1, else
* return 0 and add the sha1 of this onion to the tree.
*/
int find_tracked_onion(unsigned char *onion, uint32_t onionlen) {
static struct tracked_onion *head_tracked_onions = NULL; /* linked list of tracked onions */
static struct tracked_onion *tail_tracked_onions = NULL;
uint32_t now = time(NULL);
struct tracked_onion *to;
/* first take this opportunity to see if there are any expired
* onions in the tree. we know this in O(1) because the linked list
* 'tracked_onions' is ordered by when they were seen.
*/
while(head_tracked_onions && (head_tracked_onions->expire < now)) {
to = head_tracked_onions;
log(LOG_DEBUG,"find_tracked_onion(): Forgetting old onion (expires %d)", to->expire);
head_tracked_onions = to->next;
if(!head_tracked_onions) /* if there are no more, */
tail_tracked_onions = NULL; /* then make sure the list's tail knows that too */
RB_REMOVE(tracked_tree, &tracked_root, to);
free(to);
return -1;
}
to = malloc(sizeof(struct tracked_onion));
/* compute the SHA digest of the onion */
crypto_SHA_digest(onion, onionlen, to->digest);
/* try adding it to the tree. if it's already there it will return it. */
if(RB_INSERT(tracked_tree, &tracked_root, to)) {
/* yes, it's already there: this is a replay. */
free(to);
return 1;
}
/* this is a new onion. add it to the list. */
to->expire = ntohl(*(uint32_t *)(onion+8)); /* set the expiration date */
to->next = NULL;
if (!*tracked_onions) {
to->prev = NULL;
*tracked_onions = to;
if (!head_tracked_onions) {
head_tracked_onions = to;
} else {
to->prev = *last_tracked_onion;
(*last_tracked_onion)->next = to;
tail_tracked_onions->next = to;
}
*last_tracked_onion = to;
tail_tracked_onions = to;
log(LOG_DEBUG,"find_tracked_onion(): Remembered new onion (expires %d)", to->expire);
return 0;
}
/* delete a tracked onion entry */
void remove_tracked_onion(tracked_onion_t *to, tracked_onion_t **tracked_onions, tracked_onion_t **last_tracked_onion)
{
assert(*tracked_onions && *last_tracked_onion && to);
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(to);
return;
}
/* find a tracked onion in the linked list of tracked onions */
tracked_onion_t *find_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(digest, to->digest, 20))
return to;
to = (tracked_onion_t *)to->next;
}
return NULL;
}

23
src/or/or.h
View File

@ -355,13 +355,6 @@ typedef struct
#define ONION_LAYER_SIZE 28
#define ONION_PADDING_SIZE (128-ONION_LAYER_SIZE)
typedef struct {
uint32_t expire;
char digest[20]; /* SHA digest of the onion */
void *prev;
void *next;
} tracked_onion_t;
typedef struct {
char *LogLevel;
char *RouterFile;
@ -669,6 +662,9 @@ int chooselen(double cw);
*/
unsigned int *new_route(double cw, routerinfo_t **rarray, int rarray_len, int *routelen);
/* create a cipher by onion cipher type. */
crypto_cipher_env_t *create_onion_cipher(int cipher_type, char *key, char *iv, int encrypt_mode);
/* creates a new onion from route, stores it and its length into bufp and lenp respectively */
unsigned char *create_onion(routerinfo_t **rarray, int rarray_len, unsigned int *route, int routelen, int *len, crypt_path_t **cpath);
@ -682,17 +678,8 @@ int decrypt_onion(unsigned char *onion, uint32_t onionlen, crypto_pk_env_t *prke
/* 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);
/* create a new tracked_onion entry */
int add_tracked_onion(unsigned char *onion, uint32_t onionlen, tracked_onion_t **tracked_onions, tracked_onion_t **last_tracked_onion);
/* delete a tracked onion entry */
void remove_tracked_onion(tracked_onion_t *to, tracked_onion_t **tracked_onions, tracked_onion_t **last_tracked_onion);
/* find a tracked onion in the linked list of tracked onions */
tracked_onion_t *find_tracked_onion(unsigned char *onion, uint32_t onionlen, tracked_onion_t *tracked_onions);
/* create a cipher by onion cipher type. */
crypto_cipher_env_t *create_onion_cipher(int cipher_type, char *key, char *iv, int encrypt_mode);
void init_tracked_tree(void);
int find_tracked_onion(unsigned char *onion, uint32_t onionlen);
/********************************* routers.c ***************************/