/* Copyright 2004 Roger Dingledine */
/* See LICENSE for licensing information */
/* $Id$ */
/**
* \file rendcommon.c
* \brief Rendezvous implementation: shared code between
* introducers, services, clients, and rendezvous points.
**/
#include "or.h"
/** Return 0 if one and two are the same service ids, else -1 or 1 */
int rend_cmp_service_ids(const char *one, const char *two) {
return strcasecmp(one,two);
}
/** Free the storage held by the service descriptor desc.
*/
void rend_service_descriptor_free(rend_service_descriptor_t *desc)
{
int i;
if (desc->pk)
crypto_free_pk_env(desc->pk);
if (desc->intro_points) {
for (i=0; i < desc->n_intro_points; ++i) {
tor_free(desc->intro_points[i]);
}
tor_free(desc->intro_points);
}
tor_free(desc);
}
/** Encode a service descriptor for desc, and sign it with
* key. Store the descriptor in *str_out, and set
* *len_out to its length.
*/
int
rend_encode_service_descriptor(rend_service_descriptor_t *desc,
crypto_pk_env_t *key,
char **str_out, int *len_out)
{
char *buf, *cp, *ipoint;
int i, keylen, asn1len;
keylen = crypto_pk_keysize(desc->pk);
buf = tor_malloc(keylen*2); /* Too long, but that's okay. */
asn1len = crypto_pk_asn1_encode(desc->pk, buf, keylen*2);
if (asn1len<0) {
tor_free(buf);
return -1;
}
*len_out = 2 + asn1len + 4 + 2 + keylen;
for (i = 0; i < desc->n_intro_points; ++i) {
*len_out += strlen(desc->intro_points[i]) + 1;
}
cp = *str_out = tor_malloc(*len_out);
set_uint16(cp, htons((uint16_t)asn1len));
cp += 2;
memcpy(cp, buf, asn1len);
tor_free(buf);
cp += asn1len;
set_uint32(cp, htonl((uint32_t)desc->timestamp));
cp += 4;
set_uint16(cp, htons((uint16_t)desc->n_intro_points));
cp += 2;
for (i=0; i < desc->n_intro_points; ++i) {
ipoint = (char*)desc->intro_points[i];
strcpy(cp, ipoint);
cp += strlen(ipoint)+1;
}
i = crypto_pk_private_sign_digest(key, *str_out, cp-*str_out, cp);
if (i<0) {
tor_free(*str_out);
return -1;
}
cp += i;
tor_assert(*len_out == (cp-*str_out));
return 0;
}
/** Parse a service descriptor at str (len bytes). On
* success, return a newly alloced service_descriptor_t. On failure,
* return NULL.
*/
rend_service_descriptor_t *rend_parse_service_descriptor(
const char *str, int len)
{
rend_service_descriptor_t *result = NULL;
int keylen, asn1len, i;
const char *end, *cp, *eos;
result = tor_malloc_zero(sizeof(rend_service_descriptor_t));
cp = str;
end = str+len;
if (end-cp < 2) goto truncated;
asn1len = ntohs(get_uint16(cp));
cp += 2;
if (end-cp < asn1len) goto truncated;
result->pk = crypto_pk_asn1_decode(cp, asn1len);
if (!result->pk) goto truncated;
cp += asn1len;
if (end-cp < 4) goto truncated;
result->timestamp = (time_t) ntohl(get_uint32(cp));
cp += 4;
if (end-cp < 2) goto truncated;
result->n_intro_points = ntohs(get_uint16(cp));
result->intro_points = tor_malloc_zero(sizeof(char*)*result->n_intro_points);
cp += 2;
for (i=0;in_intro_points;++i) {
if (end-cp < 2) goto truncated;
eos = (const char *)memchr(cp,'\0',end-cp);
if (!eos) goto truncated;
result->intro_points[i] = tor_strdup(cp);
cp = eos+1;
}
keylen = crypto_pk_keysize(result->pk);
if (end-cp < keylen) goto truncated;
if (end-cp > keylen) {
log_fn(LOG_WARN, "Signature too long on service descriptor");
goto error;
}
if (crypto_pk_public_checksig_digest(result->pk,
(char*)str,cp-str, /* data */
(char*)cp,end-cp /* signature*/
)<0) {
log_fn(LOG_WARN, "Bad signature on service descriptor");
goto error;
}
return result;
truncated:
log_fn(LOG_WARN, "Truncated service descriptor");
error:
rend_service_descriptor_free(result);
return NULL;
}
/** Sets out to the first 10 bytes of the digest of pk,
* base32 encoded. NUL-terminates out. (We use this string to
* identify services in directory requests and .onion URLs.)
*/
int rend_get_service_id(crypto_pk_env_t *pk, char *out)
{
char buf[DIGEST_LEN];
tor_assert(pk);
if (crypto_pk_get_digest(pk, buf) < 0)
return -1;
if (base32_encode(out, REND_SERVICE_ID_LEN+1, buf, 10) < 0)
return -1;
return 0;
}
/* ==== Rendezvous service descriptor cache. */
#define REND_CACHE_MAX_AGE (24*60*60)
#define REND_CACHE_MAX_SKEW (90*60)
/** Map from service id (as generated by rend_get_service_id) to
* rend_cache_entry_t. */
static strmap_t *rend_cache = NULL;
/** Initializes the service descriptor cache.
*/
void rend_cache_init(void)
{
rend_cache = strmap_new();
}
/** Removes all old entries from the service descriptor cache.
*/
void rend_cache_clean(void)
{
strmap_iter_t *iter;
const char *key;
void *val;
rend_cache_entry_t *ent;
time_t cutoff;
cutoff = time(NULL) - REND_CACHE_MAX_AGE;
for (iter = strmap_iter_init(rend_cache); !strmap_iter_done(iter); ) {
strmap_iter_get(iter, &key, &val);
ent = (rend_cache_entry_t*)val;
if (ent->parsed->timestamp < cutoff) {
iter = strmap_iter_next_rmv(rend_cache, iter);
rend_service_descriptor_free(ent->parsed);
tor_free(ent->desc);
tor_free(ent);
} else {
iter = strmap_iter_next(rend_cache, iter);
}
}
}
/** Return true iff query is a syntactically valid service ID (as
* generated by rend_get_service_id). */
int rend_valid_service_id(const char *query) {
if(strlen(query) != REND_SERVICE_ID_LEN)
return 0;
if (strspn(query, BASE32_CHARS) != REND_SERVICE_ID_LEN)
return 0;
return 1;
}
/** If we have a cached rend_cache_entry_t for the service ID query, set
* *e to that entry and return 1. Else return 0.
*/
int rend_cache_lookup_entry(const char *query, rend_cache_entry_t **e)
{
tor_assert(rend_cache);
if (!rend_valid_service_id(query))
return -1;
*e = strmap_get_lc(rend_cache, query);
if (!*e)
return 0;
return 1;
}
/** query is a base-32'ed service id. If it's malformed, return -1.
* Else look it up.
* - If it is found, point *desc to it, and write its length into
* *desc_len, and return 1.
* - If it is not found, return 0.
* Note: calls to rend_cache_clean or rend_cache_store may invalidate
* *desc.
*/
int rend_cache_lookup_desc(const char *query, const char **desc, int *desc_len)
{
rend_cache_entry_t *e;
int r;
r = rend_cache_lookup_entry(query,&e);
if (r <= 0) return r;
*desc = e->desc;
*desc_len = e->len;
return 1;
}
/** Parse *desc, calculate its service id, and store it in the cache.
* If we have a newer descriptor with the same ID, ignore this one.
* If we have an older descriptor with the same ID, replace it.
* Returns -1 if it's malformed or otherwise rejected, else return 0.
*/
int rend_cache_store(const char *desc, int desc_len)
{
rend_cache_entry_t *e;
rend_service_descriptor_t *parsed;
char query[REND_SERVICE_ID_LEN+1];
time_t now;
tor_assert(rend_cache);
parsed = rend_parse_service_descriptor(desc,desc_len);
if (!parsed) {
log_fn(LOG_WARN,"Couldn't parse service descriptor");
return -1;
}
if (rend_get_service_id(parsed->pk, query)<0) {
log_fn(LOG_WARN,"Couldn't compute service ID");
rend_service_descriptor_free(parsed);
return -1;
}
now = time(NULL);
if (parsed->timestamp < now-REND_CACHE_MAX_AGE) {
log_fn(LOG_WARN,"Service descriptor %s is too old", query);
rend_service_descriptor_free(parsed);
return -1;
}
if (parsed->timestamp > now+REND_CACHE_MAX_SKEW) {
log_fn(LOG_WARN,"Service descriptor %s is too far in the future", query);
rend_service_descriptor_free(parsed);
return -1;
}
e = (rend_cache_entry_t*) strmap_get_lc(rend_cache, query);
if (e && e->parsed->timestamp > parsed->timestamp) {
log_fn(LOG_INFO,"We already have a newer service descriptor %s with the same ID", query);
rend_service_descriptor_free(parsed);
return 0;
}
if (e && e->len == desc_len && !memcmp(desc,e->desc,desc_len)) {
log_fn(LOG_INFO,"We already have this service descriptor %s", query);
e->received = time(NULL);
rend_service_descriptor_free(parsed);
return 0;
}
if (!e) {
e = tor_malloc_zero(sizeof(rend_cache_entry_t));
strmap_set_lc(rend_cache, query, e);
} else {
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
}
e->received = time(NULL);
e->parsed = parsed;
e->len = desc_len;
e->desc = tor_malloc(desc_len);
memcpy(e->desc, desc, desc_len);
log_fn(LOG_INFO,"Successfully stored rend desc '%s', len %d", query, desc_len);
return 0;
}
/** Called when we get a rendezvous-related relay cell on circuit
* circ. Dispatch on rendezvous relay command. */
void rend_process_relay_cell(circuit_t *circ, int command, int length,
const char *payload)
{
int r;
switch(command) {
case RELAY_COMMAND_ESTABLISH_INTRO:
r = rend_mid_establish_intro(circ,payload,length);
break;
case RELAY_COMMAND_ESTABLISH_RENDEZVOUS:
r = rend_mid_establish_rendezvous(circ,payload,length);
break;
case RELAY_COMMAND_INTRODUCE1:
r = rend_mid_introduce(circ,payload,length);
break;
case RELAY_COMMAND_INTRODUCE2:
r = rend_service_introduce(circ,payload,length);
break;
case RELAY_COMMAND_INTRODUCE_ACK:
r = rend_client_introduction_acked(circ,payload,length);
break;
case RELAY_COMMAND_RENDEZVOUS1:
r = rend_mid_rendezvous(circ,payload,length);
break;
case RELAY_COMMAND_RENDEZVOUS2:
r = rend_client_receive_rendezvous(circ,payload,length);
break;
case RELAY_COMMAND_INTRO_ESTABLISHED:
r = rend_service_intro_established(circ,payload,length);
break;
case RELAY_COMMAND_RENDEZVOUS_ESTABLISHED:
r = rend_client_rendezvous_acked(circ,payload,length);
break;
default:
tor_assert(0);
}
}
/*
Local Variables:
mode:c
indent-tabs-mode:nil
c-basic-offset:2
End:
*/