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/* Copyright 2004 Roger Dingledine */
/* See LICENSE for licensing information */
/* $Id$ */
#include "or.h"
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);
}
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;
char digest[CRYPTO_SHA1_DIGEST_LEN];
keylen = crypto_pk_keysize(desc->pk);
buf = tor_malloc(keylen*2); /* XXXX */
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, (uint16_t)asn1len);
cp += 2;
memcpy(cp, buf, asn1len);
tor_free(buf);
cp += asn1len;
set_uint32(cp, (uint32_t)desc->timestamp);
cp += 4;
set_uint16(cp, (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_SHA_digest(*str_out, cp-*str_out, digest);
if (i<0) {
tor_free(*str_out);
return -1;
}
i = crypto_pk_private_sign(key, digest, CRYPTO_SHA1_DIGEST_LEN, cp);
if (i<0) {
tor_free(*str_out);
return -1;
}
cp += i;
assert(*len_out == (cp-*str_out));
return 0;
}
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;
char *signed_data=NULL;
char digest_expected[CRYPTO_SHA1_DIGEST_LEN];
result = tor_malloc_zero(sizeof(rend_service_descriptor_t));
cp = str;
end = str+len;
if (end-cp < 2) goto truncated;
asn1len = 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) get_uint32(cp);
cp += 4;
if (end-cp < 2) goto truncated;
result->n_intro_points = get_uint16(cp);
result->intro_points = tor_malloc_zero(sizeof(char*)*result->n_intro_points);
cp += 2;
for (i=0;i<result->n_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 (crypto_SHA_digest(str, cp-str, digest_expected)<0) {
log_fn(LOG_WARN, "Error computing SHA1 digest.");
goto error;
}
signed_data = tor_malloc(keylen+1);
i = crypto_pk_public_checksig(result->pk, (char*)cp, end-cp, signed_data);
if (i<0) {
log_fn(LOG_WARN, "Invalid signature on service descriptor");
goto error;
}
if (i != CRYPTO_SHA1_DIGEST_LEN ||
memcmp(signed_data, digest_expected, CRYPTO_SHA1_DIGEST_LEN)) {
log_fn(LOG_WARN, "Mismatched signature on service descriptor");
goto error;
}
tor_free(signed_data);
return result;
truncated:
log_fn(LOG_WARN, "Truncated service descriptor");
error:
tor_free(signed_data);
rend_service_descriptor_free(result);
return NULL;
}
int rend_get_service_id(crypto_pk_env_t *pk, char *out)
{
char buf[CRYPTO_SHA1_DIGEST_LEN];
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;
}
/* ==== Hidden service descriptor cache. */
#define HIDSERV_MAX_AGE 24*60*60
#define HIDSERV_MAX_SKEW 60*60
typedef struct hidserv_cache_entry_t {
int len;
char *desc;
rend_service_descriptor_t *parsed;
} hidserv_cache_entry_t;
static strmap_t *hidserv_cache = NULL;
void hidserv_cache_init(void)
{
hidserv_cache = strmap_new();
}
void hidserv_cache_clean(void)
{
strmap_iter_t *iter;
const char *key;
void *val;
hidserv_cache_entry_t *ent;
time_t cutoff;
cutoff = time(NULL) - HIDSERV_MAX_AGE;
for (iter = strmap_iter_init(hidserv_cache); !strmap_iter_done(iter); ) {
strmap_iter_get(iter, &key, &val);
ent = (hidserv_cache_entry_t*)val;
if (ent->parsed->timestamp < cutoff) {
iter = strmap_iter_next_rmv(hidserv_cache, iter);
rend_service_descriptor_free(ent->parsed);
tor_free(ent->desc);
tor_free(ent);
} else {
iter = strmap_iter_next(hidserv_cache, iter);
}
}
}
int hidserv_lookup(char *query, const char **desc, int *desc_len)
{
hidserv_cache_entry_t *e;
assert(hidserv_cache);
if (strlen(query) != REND_SERVICE_ID_LEN)
return -1; /* XXXX also check for bad chars. */
e = (hidserv_cache_entry_t*) strmap_get_lc(hidserv_cache, query);
if (!e)
return 0;
*desc = e->desc;
*desc_len = e->len;
return 1;
}
int hidserv_store(char *desc, int desc_len)
{
hidserv_cache_entry_t *e;
rend_service_descriptor_t *parsed;
char query[REND_SERVICE_ID_LEN+1];
time_t now;
assert(hidserv_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-HIDSERV_MAX_AGE) {
log_fn(LOG_WARN,"Service descriptor is too old");
rend_service_descriptor_free(parsed);
return -1;
}
if (parsed->timestamp > now+HIDSERV_MAX_SKEW) {
log_fn(LOG_WARN,"Service descriptor is too far in the future");
rend_service_descriptor_free(parsed);
return -1;
}
e = (hidserv_cache_entry_t*) strmap_get_lc(hidserv_cache, query);
if (e && e->parsed->timestamp > parsed->timestamp) {
log_fn(LOG_WARN,"We already have a newer service descriptor with the same ID");
rend_service_descriptor_free(parsed);
return -1;
}
if (e && e->len == desc_len && !memcmp(desc,e->desc,desc_len)) {
log_fn(LOG_WARN,"We already have this service descriptor");
rend_service_descriptor_free(parsed);
return -1;
}
if (!e) {
e = tor_malloc_zero(sizeof(hidserv_cache_entry_t));
strmap_set_lc(hidserv_cache, query, e);
} else {
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
}
e->parsed = parsed;
e->len = desc_len;
e->desc = tor_strdup(desc);
return 0;
}
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