Macros | Functions
replaycache.c File Reference

Self-scrubbing replay cache for rendservice.c. More...

#include "core/or/or.h"
#include "feature/hs_common/replaycache.h"

Go to the source code of this file.


void replaycache_free_ (replaycache_t *r)
replaycache_t * replaycache_new (time_t horizon, time_t interval)
STATIC int replaycache_add_and_test_internal (time_t present, replaycache_t *r, const void *data, size_t len, time_t *elapsed)
STATIC void replaycache_scrub_if_needed_internal (time_t present, replaycache_t *r)
int replaycache_add_and_test (replaycache_t *r, const void *data, size_t len)
int replaycache_add_test_and_elapsed (replaycache_t *r, const void *data, size_t len, time_t *elapsed)
void replaycache_scrub_if_needed (replaycache_t *r)

Detailed Description

Self-scrubbing replay cache for rendservice.c.

To prevent replay attacks, hidden services need to recognize INTRODUCE2 cells that they've already seen, and drop them. If they didn't, then sending the same INTRODUCE2 cell over and over would force the hidden service to make a huge number of circuits to the same rendezvous point, aiding traffic analysis.

(It's not that simple, actually. We only check for replays in the RSA-encrypted portion of the handshake, since the rest of the handshake is malleable.)

This module is used from rendservice.c.

Definition in file replaycache.c.

Macro Definition Documentation



Definition at line 22 of file replaycache.c.

Function Documentation

◆ replaycache_add_and_test()

int replaycache_add_and_test ( replaycache_t *  r,
const void *  data,
size_t  len 

Test the buffer of length len point to by data against the replay cache r; the digest of the buffer will be added to the cache at the current time, and the function will return 1 if it was already seen within the cache's horizon, or 0 otherwise.

Definition at line 186 of file replaycache.c.

◆ replaycache_add_and_test_internal()

STATIC int replaycache_add_and_test_internal ( time_t  present,
replaycache_t *  r,
const void *  data,
size_t  len,
time_t *  elapsed 

See documentation for replaycache_add_and_test().

Definition at line 76 of file replaycache.c.

Referenced by replaycache_add_and_test(), and replaycache_add_test_and_elapsed().

◆ replaycache_add_test_and_elapsed()

int replaycache_add_test_and_elapsed ( replaycache_t *  r,
const void *  data,
size_t  len,
time_t *  elapsed 

Like replaycache_add_and_test(), but if it's a hit also return the time elapsed since this digest was last seen.

Definition at line 195 of file replaycache.c.

Referenced by hs_circ_handle_introduce2().

◆ replaycache_free_()

void replaycache_free_ ( replaycache_t *  r)

Free the replaycache r and all of its entries.

Definition at line 30 of file replaycache.c.

◆ replaycache_new()

replaycache_t * replaycache_new ( time_t  horizon,
time_t  interval 

Allocate a new, empty replay detection cache, where horizon is the time for entries to age out and interval is the time after which the cache should be scrubbed for old entries.

Definition at line 47 of file replaycache.c.

◆ replaycache_scrub_if_needed()

void replaycache_scrub_if_needed ( replaycache_t *  r)

Scrub aged entries out of r if sufficiently long has elapsed since r was last scrubbed.

Definition at line 205 of file replaycache.c.

◆ replaycache_scrub_if_needed_internal()

STATIC void replaycache_scrub_if_needed_internal ( time_t  present,
replaycache_t *  r 

See documentation for replaycache_scrub_if_needed().

Definition at line 139 of file replaycache.c.

Referenced by replaycache_scrub_if_needed().