/* 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: */