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- /* Copyright 2001,2002,2003 Roger Dingledine, Matej Pfajfar. */
- /* See LICENSE for licensing information */
- /* $Id$ */
- #include "or.h"
- extern or_options_t options; /* command-line and config-file options */
- static int count_acceptable_routers(routerinfo_t **rarray, int rarray_len);
- int decide_circ_id_type(char *local_nick, char *remote_nick) {
- int result;
- assert(remote_nick);
- if(!local_nick)
- return CIRC_ID_TYPE_LOWER;
- result = strcmp(local_nick, remote_nick);
- assert(result);
- if(result < 0)
- return CIRC_ID_TYPE_LOWER;
- return CIRC_ID_TYPE_HIGHER;
- }
- struct onion_queue_t {
- circuit_t *circ;
- struct onion_queue_t *next;
- };
- /* global (within this file) variables used by the next few functions */
- static struct onion_queue_t *ol_list=NULL;
- static struct onion_queue_t *ol_tail=NULL;
- static int ol_length=0;
- int onion_pending_add(circuit_t *circ) {
- struct onion_queue_t *tmp;
- tmp = tor_malloc(sizeof(struct onion_queue_t));
- tmp->circ = circ;
- tmp->next = NULL;
- if(!ol_tail) {
- assert(!ol_list);
- assert(!ol_length);
- ol_list = tmp;
- ol_tail = tmp;
- ol_length++;
- return 0;
- }
- assert(ol_list);
- assert(!ol_tail->next);
- if(ol_length >= options.MaxOnionsPending) {
- log_fn(LOG_WARN,"Already have %d onions queued. Closing.", ol_length);
- free(tmp);
- return -1;
- }
- ol_length++;
- ol_tail->next = tmp;
- ol_tail = tmp;
- return 0;
- }
- circuit_t *onion_next_task(void) {
- circuit_t *circ;
- if(!ol_list)
- return NULL; /* no onions pending, we're done */
- assert(ol_list->circ);
- assert(ol_list->circ->p_conn); /* make sure it's still valid */
- assert(ol_length > 0);
- circ = ol_list->circ;
- onion_pending_remove(ol_list->circ);
- return circ;
- }
- /* go through ol_list, find the onion_queue_t element which points to
- * circ, remove and free that element. leave circ itself alone.
- */
- void onion_pending_remove(circuit_t *circ) {
- struct onion_queue_t *tmpo, *victim;
- if(!ol_list)
- return; /* nothing here. */
- /* first check to see if it's the first entry */
- tmpo = ol_list;
- if(tmpo->circ == circ) {
- /* it's the first one. remove it from the list. */
- ol_list = tmpo->next;
- if(!ol_list)
- ol_tail = NULL;
- ol_length--;
- victim = tmpo;
- } else { /* we need to hunt through the rest of the list */
- for( ;tmpo->next && tmpo->next->circ != circ; tmpo=tmpo->next) ;
- if(!tmpo->next) {
- log_fn(LOG_DEBUG,"circ (p_circ_id %d) not in list, probably at cpuworker.",circ->p_circ_id);
- return;
- }
- /* now we know tmpo->next->circ == circ */
- victim = tmpo->next;
- tmpo->next = victim->next;
- if(ol_tail == victim)
- ol_tail = tmpo;
- ol_length--;
- }
- /* now victim points to the element that needs to be removed */
- free(victim);
- }
- /* given a response payload and keys, initialize, then send a created cell back */
- int onionskin_answer(circuit_t *circ, unsigned char *payload, unsigned char *keys) {
- unsigned char iv[16];
- cell_t cell;
- memset(iv, 0, 16);
- memset(&cell, 0, sizeof(cell_t));
- cell.command = CELL_CREATED;
- cell.circ_id = circ->p_circ_id;
- circ->state = CIRCUIT_STATE_OPEN;
- log_fn(LOG_DEBUG,"Entering.");
- memcpy(cell.payload, payload, ONIONSKIN_REPLY_LEN);
- log_fn(LOG_INFO,"init digest forward %d, backward %d.",
- (int)*(uint32_t*)(keys), (int)*(uint32_t*)(keys+20));
- circ->n_digest = crypto_new_digest_env(CRYPTO_SHA1_DIGEST);
- crypto_digest_add_bytes(circ->n_digest, keys, 20);
- circ->p_digest = crypto_new_digest_env(CRYPTO_SHA1_DIGEST);
- crypto_digest_add_bytes(circ->p_digest, keys+20, 20);
- log_fn(LOG_DEBUG,"init cipher forward %d, backward %d.",
- (int)*(uint32_t*)(keys+40), (int)*(uint32_t*)(keys+40+16));
- if (!(circ->n_crypto =
- crypto_create_init_cipher(CIRCUIT_CIPHER,keys+40,iv,0))) {
- log_fn(LOG_WARN,"Cipher initialization failed (n).");
- return -1;
- }
- if (!(circ->p_crypto =
- crypto_create_init_cipher(CIRCUIT_CIPHER,keys+40+16,iv,1))) {
- log_fn(LOG_WARN,"Cipher initialization failed (p).");
- return -1;
- }
- connection_or_write_cell_to_buf(&cell, circ->p_conn);
- log_fn(LOG_DEBUG,"Finished sending 'created' cell.");
- return 0;
- }
- static void add_nickname_list_to_smartlist(smartlist_t *sl, char *list) {
- char *start,*end;
- char nick[MAX_NICKNAME_LEN];
- routerinfo_t *router;
- while(isspace(*list) || *list==',') list++;
- start = list;
- while(*start) {
- end=start; while(*end && !isspace(*end) && *end != ',') end++;
- memcpy(nick,start,end-start);
- nick[end-start] = 0; /* null terminate it */
- router = router_get_by_nickname(nick);
- if(router && router->is_running)
- smartlist_add(sl,router);
- else
- log_fn(LOG_WARN,"Nickname list includes '%s' which isn't a known router.",nick);
- while(isspace(*end) || *end==',') end++;
- start = end;
- }
- }
- static int new_route_len(double cw, routerinfo_t **rarray, int rarray_len) {
- int num_acceptable_routers;
- int routelen;
- assert((cw >= 0) && (cw < 1) && rarray); /* valid parameters */
- #ifdef TOR_PERF
- routelen = 2;
- #else
- routelen = 3;
- #endif
- #if 0
- for(routelen = 3; ; routelen++) { /* 3, increment until coinflip says we're done */
- if (crypto_pseudo_rand_int(255) >= cw*255) /* don't extend */
- break;
- }
- #endif
- log_fn(LOG_DEBUG,"Chosen route length %d (%d routers available).",routelen, rarray_len);
- num_acceptable_routers = count_acceptable_routers(rarray, rarray_len);
- if(num_acceptable_routers < 2) {
- log_fn(LOG_INFO,"Not enough acceptable routers. Failing.");
- return -1;
- }
- if(num_acceptable_routers < routelen) {
- log_fn(LOG_INFO,"Not enough routers: cutting routelen from %d to %d.",
- routelen, num_acceptable_routers);
- routelen = num_acceptable_routers;
- }
- return routelen;
- }
- static routerinfo_t *choose_good_exit_server(routerlist_t *dir)
- {
- int *n_supported;
- int *n_maybe_supported;
- int i, j;
- int n_pending_connections = 0;
- connection_t **carray;
- int n_connections;
- int best_support = -1;
- int best_maybe_support = -1;
- int best_support_idx = -1;
- int best_maybe_support_idx = -1;
- int n_best_support=0, n_best_maybe_support=0;
- smartlist_t *sl, *preferredexits, *excludedexits;
- routerinfo_t *router;
- get_connection_array(&carray, &n_connections);
- /* Count how many connections are waiting for a circuit to be built.
- * We use this for log messages now, but in the future we may depend on it.
- */
- for (i = 0; i < n_connections; ++i) {
- if (carray[i]->type == CONN_TYPE_AP &&
- carray[i]->state == AP_CONN_STATE_CIRCUIT_WAIT &&
- !carray[i]->marked_for_close &&
- !circuit_stream_is_being_handled(carray[i]))
- ++n_pending_connections;
- }
- log_fn(LOG_DEBUG, "Choosing exit node; %d connections are pending",
- n_pending_connections);
- /* Now we count, for each of the routers in the directory: how many
- * of the pending connections could _definitely_ exit from that
- * router (n_supported[i]) and how many could _possibly_ exit from
- * that router (n_maybe_supported[i]). (We can't be sure about
- * cases where we don't know the IP address of the pending
- * connection.)
- */
- n_supported = tor_malloc(sizeof(int)*dir->n_routers);
- n_maybe_supported = tor_malloc(sizeof(int)*dir->n_routers);
- for (i = 0; i < dir->n_routers; ++i) { /* iterate over routers */
- if(!dir->routers[i]->is_running) {
- n_supported[i] = n_maybe_supported[i] = -1;
- log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- directory says it's not running.",
- dir->routers[i]->nickname, i);
- continue; /* skip routers that are known to be down */
- }
- if(router_exit_policy_rejects_all(dir->routers[i])) {
- n_supported[i] = n_maybe_supported[i] = -1;
- log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- it rejects all.",
- dir->routers[i]->nickname, i);
- continue; /* skip routers that reject all */
- }
- n_supported[i] = n_maybe_supported[i] = 0;
- for (j = 0; j < n_connections; ++j) { /* iterate over connections */
- if (carray[j]->type != CONN_TYPE_AP ||
- carray[j]->state != AP_CONN_STATE_CIRCUIT_WAIT ||
- carray[j]->marked_for_close ||
- circuit_stream_is_being_handled(carray[j]))
- continue; /* Skip everything but APs in CIRCUIT_WAIT */
- switch (connection_ap_can_use_exit(carray[j], dir->routers[i]))
- {
- case -1:
- log_fn(LOG_DEBUG,"%s (index %d) would reject this stream.",
- dir->routers[i]->nickname, i);
- break; /* would be rejected; try next connection */
- case 0:
- ++n_supported[i];
- log_fn(LOG_DEBUG,"%s is supported. n_supported[%d] now %d.",
- dir->routers[i]->nickname, i, n_supported[i]);
- ; /* Fall through: If it is supported, it is also maybe supported. */
- case 1:
- ++n_maybe_supported[i];
- log_fn(LOG_DEBUG,"%s is maybe supported. n_maybe_supported[%d] now %d.",
- dir->routers[i]->nickname, i, n_maybe_supported[i]);
- }
- } /* End looping over connections. */
- if (n_supported[i] > best_support) {
- /* If this router is better than previous ones, remember its index
- * and goodness, and start counting how many routers are this good. */
- best_support = n_supported[i]; best_support_idx = i; n_best_support=1;
- log_fn(LOG_DEBUG,"%s is new best supported option so far.",
- dir->routers[i]->nickname);
- } else if (n_supported[i] == best_support) {
- /* If this router is _as good_ as the best one, just increment the
- * count of equally good routers.*/
- ++n_best_support;
- }
- /* As above, but for 'maybe-supported' connections */
- if (n_maybe_supported[i] > best_maybe_support) {
- best_maybe_support = n_maybe_supported[i]; best_maybe_support_idx = i;
- n_best_maybe_support = 1;
- log_fn(LOG_DEBUG,"%s is new best maybe-supported option so far.",
- dir->routers[i]->nickname);
- } else if (n_maybe_supported[i] == best_maybe_support) {
- ++n_best_maybe_support;
- }
- }
- log_fn(LOG_INFO, "Found %d servers that will definitely support %d/%d "
- "pending connections, and %d that might support %d/%d.",
- n_best_support, best_support, n_pending_connections,
- n_best_maybe_support, best_maybe_support, n_pending_connections);
- preferredexits = smartlist_create(MAX_ROUTERS_IN_DIR);
- add_nickname_list_to_smartlist(preferredexits,options.ExitNodes);
- excludedexits = smartlist_create(MAX_ROUTERS_IN_DIR);
- add_nickname_list_to_smartlist(excludedexits,options.ExcludedNodes);
- sl = smartlist_create(MAX_ROUTERS_IN_DIR);
- /* If any routers definitely support any pending connections, choose one
- * at random. */
- if (best_support > 0) {
- for (i = best_support_idx; i < dir->n_routers; i++)
- if (n_supported[i] == best_support)
- smartlist_add(sl, dir->routers[i]);
- smartlist_subtract(sl,excludedexits);
- if (smartlist_overlap(sl,preferredexits))
- smartlist_intersect(sl,preferredexits);
- router = smartlist_choose(sl);
- } else if (best_maybe_support > 0) {
- /* If any routers _maybe_ support pending connections, choose one at
- * random, as above. */
- for(i = best_maybe_support_idx; i < dir->n_routers; i++)
- if(n_maybe_supported[i] == best_maybe_support)
- smartlist_add(sl, dir->routers[i]);
- smartlist_subtract(sl,excludedexits);
- if (smartlist_overlap(sl,preferredexits))
- smartlist_intersect(sl,preferredexits);
- router = smartlist_choose(sl);
- } else {
- /* Either there are no pending connections, or no routers even seem to
- * possibly support any of them. Choose a router at random. */
- if (best_maybe_support == -1) {
- log(LOG_WARN, "All routers are down or middleman -- choosing a doomed exit at random.");
- }
- for(i = best_maybe_support_idx; i < dir->n_routers; i++)
- if(n_supported[i] != -1)
- smartlist_add(sl, dir->routers[i]);
- smartlist_subtract(sl,excludedexits);
- if (smartlist_overlap(sl,preferredexits))
- smartlist_intersect(sl,preferredexits);
- router = smartlist_choose(sl);
- }
- smartlist_free(preferredexits);
- smartlist_free(excludedexits);
- smartlist_free(sl);
- tor_free(n_supported); tor_free(n_maybe_supported);
- if(router) {
- log_fn(LOG_DEBUG, "Chose exit server '%s'", router->nickname);
- return router;
- }
- log_fn(LOG_WARN, "No exit routers seem to be running; can't choose an exit.");
- return NULL;
- }
- cpath_build_state_t *onion_new_cpath_build_state(void) {
- routerlist_t *rl;
- int r;
- cpath_build_state_t *info;
- routerinfo_t *exit;
- router_get_routerlist(&rl);
- r = new_route_len(options.PathlenCoinWeight, rl->routers, rl->n_routers);
- if (r < 0)
- return NULL;
- exit = choose_good_exit_server(rl);
- if(!exit)
- return NULL;
- info = tor_malloc(sizeof(cpath_build_state_t));
- info->desired_path_len = r;
- info->chosen_exit = tor_strdup(exit->nickname);
- return info;
- }
- static int count_acceptable_routers(routerinfo_t **rarray, int rarray_len) {
- int i, j;
- int num=0;
- connection_t *conn;
- for(i=0;i<rarray_len;i++) {
- log_fn(LOG_DEBUG,"Contemplating whether router %d is a new option...",i);
- if(rarray[i]->is_running == 0) {
- log_fn(LOG_DEBUG,"Nope, the directory says %d is not running.",i);
- goto next_i_loop;
- }
- if(options.ORPort) {
- conn = connection_exact_get_by_addr_port(rarray[i]->addr, rarray[i]->or_port);
- if(!conn || conn->type != CONN_TYPE_OR || conn->state != OR_CONN_STATE_OPEN) {
- log_fn(LOG_DEBUG,"Nope, %d is not connected.",i);
- goto next_i_loop;
- }
- }
- for(j=0;j<i;j++) {
- if(!crypto_pk_cmp_keys(rarray[i]->onion_pkey, rarray[j]->onion_pkey)) {
- /* these guys are twins. so we've already counted him. */
- log_fn(LOG_DEBUG,"Nope, %d is a twin of %d.",i,j);
- goto next_i_loop;
- }
- }
- num++;
- log_fn(LOG_DEBUG,"I like %d. num_acceptable_routers now %d.",i, num);
- next_i_loop:
- ; /* our compiler may need an explicit statement after the label */
- }
- return num;
- }
- /* prototypes for smartlist operations from routerlist.h
- * they're here to prevent precedence issues with the .h files
- */
- void router_add_running_routers_to_smartlist(smartlist_t *sl);
- static void remove_twins_from_smartlist(smartlist_t *sl, routerinfo_t *twin) {
- int i;
- routerinfo_t *r;
- if(twin == NULL)
- return;
- /* XXX abstraction violation: this function reaches inside smartlist :( */
- for(i=0; i < sl->num_used; i++) {
- r = sl->list[i];
- if (!crypto_pk_cmp_keys(r->onion_pkey, twin->onion_pkey)) {
- sl->list[i] = sl->list[--sl->num_used]; /* swap with the end */
- i--; /* so we process the new i'th element */
- }
- }
- }
- int onion_extend_cpath(crypt_path_t **head_ptr, cpath_build_state_t *state, routerinfo_t **router_out)
- {
- int cur_len;
- crypt_path_t *cpath, *hop;
- routerinfo_t *r;
- routerinfo_t *choice;
- int i;
- smartlist_t *sl, *excludednodes;
- assert(head_ptr);
- assert(router_out);
- if (!*head_ptr) {
- cur_len = 0;
- } else {
- cur_len = 1;
- for (cpath = *head_ptr; cpath->next != *head_ptr; cpath = cpath->next) {
- ++cur_len;
- }
- }
- if (cur_len >= state->desired_path_len) {
- log_fn(LOG_DEBUG, "Path is complete: %d steps long",
- state->desired_path_len);
- return 1;
- }
- log_fn(LOG_DEBUG, "Path is %d long; we want %d", cur_len,
- state->desired_path_len);
- excludednodes = smartlist_create(MAX_ROUTERS_IN_DIR);
- add_nickname_list_to_smartlist(excludednodes,options.ExcludedNodes);
- if(cur_len == state->desired_path_len - 1) { /* Picking last node */
- log_fn(LOG_DEBUG, "Contemplating last hop: choice already made: %s",
- state->chosen_exit);
- choice = router_get_by_nickname(state->chosen_exit);
- smartlist_free(excludednodes);
- if(!choice) {
- log_fn(LOG_WARN,"Our chosen exit %s is no longer in the directory? Failing.",
- state->chosen_exit);
- return -1;
- }
- } else if(cur_len == 0) { /* picking first node */
- /* try the nodes in EntryNodes first */
- sl = smartlist_create(MAX_ROUTERS_IN_DIR);
- add_nickname_list_to_smartlist(sl,options.EntryNodes);
- /* XXX one day, consider picking chosen_exit knowing what's in EntryNodes */
- remove_twins_from_smartlist(sl,router_get_by_nickname(state->chosen_exit));
- smartlist_subtract(sl,excludednodes);
- choice = smartlist_choose(sl);
- smartlist_free(sl);
- if(!choice) {
- sl = smartlist_create(MAX_ROUTERS_IN_DIR);
- router_add_running_routers_to_smartlist(sl);
- remove_twins_from_smartlist(sl,router_get_by_nickname(state->chosen_exit));
- smartlist_subtract(sl,excludednodes);
- choice = smartlist_choose(sl);
- smartlist_free(sl);
- }
- smartlist_free(excludednodes);
- if(!choice) {
- log_fn(LOG_WARN,"No acceptable routers while picking entry node. Failing.");
- return -1;
- }
- } else {
- log_fn(LOG_DEBUG, "Contemplating intermediate hop: random choice.");
- sl = smartlist_create(MAX_ROUTERS_IN_DIR);
- router_add_running_routers_to_smartlist(sl);
- remove_twins_from_smartlist(sl,router_get_by_nickname(state->chosen_exit));
- for (i = 0, cpath = *head_ptr; i < cur_len; ++i, cpath=cpath->next) {
- r = router_get_by_addr_port(cpath->addr, cpath->port);
- assert(r);
- remove_twins_from_smartlist(sl,r);
- }
- smartlist_subtract(sl,excludednodes);
- choice = smartlist_choose(sl);
- smartlist_free(sl);
- smartlist_free(excludednodes);
- if(!choice) {
- log_fn(LOG_WARN,"No acceptable routers while picking intermediate node. Failing.");
- return -1;
- }
- }
- log_fn(LOG_DEBUG,"Chose router %s for hop %d (exit is %s)",
- choice->nickname, cur_len, state->chosen_exit);
- hop = (crypt_path_t *)tor_malloc_zero(sizeof(crypt_path_t));
- /* link hop into the cpath, at the end. */
- if (*head_ptr) {
- hop->next = (*head_ptr);
- hop->prev = (*head_ptr)->prev;
- (*head_ptr)->prev->next = hop;
- (*head_ptr)->prev = hop;
- } else {
- *head_ptr = hop;
- hop->prev = hop->next = hop;
- }
- hop->state = CPATH_STATE_CLOSED;
- hop->port = choice->or_port;
- hop->addr = choice->addr;
- hop->package_window = CIRCWINDOW_START;
- hop->deliver_window = CIRCWINDOW_START;
- log_fn(LOG_DEBUG, "Extended circuit path with %s for hop %d",
- choice->nickname, cur_len);
- *router_out = choice;
- return 0;
- }
- /*----------------------------------------------------------------------*/
- /* Given a router's 128 byte public key,
- stores the following in onion_skin_out:
- [16 bytes] Symmetric key for encrypting blob past RSA
- [112 bytes] g^x part 1 (inside the RSA)
- [16 bytes] g^x part 2 (symmetrically encrypted)
- [ 6 bytes] Meeting point (IP/port)
- [ 8 bytes] Meeting cookie
- [16 bytes] End-to-end authentication [optional]
- * Stores the DH private key into handshake_state_out for later completion
- * of the handshake.
- *
- * The meeting point/cookies and auth are zeroed out for now.
- */
- int
- onion_skin_create(crypto_pk_env_t *dest_router_key,
- crypto_dh_env_t **handshake_state_out,
- char *onion_skin_out) /* Must be ONIONSKIN_CHALLENGE_LEN bytes */
- {
- char iv[16];
- char *challenge = NULL;
- crypto_dh_env_t *dh = NULL;
- crypto_cipher_env_t *cipher = NULL;
- int dhbytes, pkbytes;
- *handshake_state_out = NULL;
- memset(onion_skin_out, 0, ONIONSKIN_CHALLENGE_LEN);
- memset(iv, 0, 16);
- if (!(dh = crypto_dh_new()))
- goto err;
- dhbytes = crypto_dh_get_bytes(dh);
- pkbytes = crypto_pk_keysize(dest_router_key);
- assert(dhbytes == 128);
- assert(pkbytes == 128);
- challenge = (char *)tor_malloc_zero(ONIONSKIN_CHALLENGE_LEN);
- if (crypto_rand(16, challenge))
- goto err;
- /* You can't just run around RSA-encrypting any bitstream: if it's
- * greater than the RSA key, then OpenSSL will happily encrypt,
- * and later decrypt to the wrong value. So we set the first bit
- * of 'challenge' to 0. This means that our symmetric key is really
- * only 127 bits.
- */
- challenge[0] &= 0x7f;
- if (crypto_dh_get_public(dh, challenge+16, dhbytes))
- goto err;
- #ifdef DEBUG_ONION_SKINS
- #define PA(a,n) \
- { int _i; for (_i = 0; _i<n; ++_i) printf("%02x ",((int)(a)[_i])&0xFF); }
- printf("Client: client g^x:");
- PA(challenge+16,3);
- printf("...");
- PA(challenge+141,3);
- puts("");
- printf("Client: client symkey:");
- PA(challenge+0,16);
- puts("");
- #endif
- /* set meeting point, meeting cookie, etc here. Leave zero for now. */
- cipher = crypto_create_init_cipher(ONION_CIPHER, challenge, iv, 1);
- if (!cipher)
- goto err;
- if (crypto_pk_public_encrypt(dest_router_key, challenge, pkbytes,
- onion_skin_out, RSA_NO_PADDING)==-1)
- goto err;
- if (crypto_cipher_encrypt(cipher, challenge+pkbytes, ONIONSKIN_CHALLENGE_LEN-pkbytes,
- onion_skin_out+pkbytes))
- goto err;
- tor_free(challenge);
- crypto_free_cipher_env(cipher);
- *handshake_state_out = dh;
- return 0;
- err:
- tor_free(challenge);
- if (dh) crypto_dh_free(dh);
- if (cipher) crypto_free_cipher_env(cipher);
- return -1;
- }
- /* Given an encrypted DH public key as generated by onion_skin_create,
- * and the private key for this onion router, generate the reply (128-byte
- * DH plus the first 20 bytes of shared key material), and store the
- * next key_out_len bytes of key material in key_out.
- */
- int
- onion_skin_server_handshake(char *onion_skin, /* ONIONSKIN_CHALLENGE_LEN bytes */
- crypto_pk_env_t *private_key,
- char *handshake_reply_out, /* ONIONSKIN_REPLY_LEN bytes */
- char *key_out,
- int key_out_len)
- {
- char challenge[ONIONSKIN_CHALLENGE_LEN];
- char iv[16];
- crypto_dh_env_t *dh = NULL;
- crypto_cipher_env_t *cipher = NULL;
- int pkbytes;
- int len;
- char *key_material=NULL;
- memset(iv, 0, 16);
- pkbytes = crypto_pk_keysize(private_key);
- if (crypto_pk_private_decrypt(private_key,
- onion_skin, pkbytes,
- challenge, RSA_NO_PADDING) == -1)
- goto err;
- #ifdef DEBUG_ONION_SKINS
- printf("Server: client symkey:");
- PA(buf+0,16);
- puts("");
- #endif
- cipher = crypto_create_init_cipher(ONION_CIPHER, challenge, iv, 0);
- if (crypto_cipher_decrypt(cipher, onion_skin+pkbytes, ONIONSKIN_CHALLENGE_LEN-pkbytes,
- challenge+pkbytes))
- goto err;
- #ifdef DEBUG_ONION_SKINS
- printf("Server: client g^x:");
- PA(buf+16,3);
- printf("...");
- PA(buf+141,3);
- puts("");
- #endif
- dh = crypto_dh_new();
- if (crypto_dh_get_public(dh, handshake_reply_out, DH_KEY_LEN))
- goto err;
- #ifdef DEBUG_ONION_SKINS
- printf("Server: server g^y:");
- PA(handshake_reply_out+0,3);
- printf("...");
- PA(handshake_reply_out+125,3);
- puts("");
- #endif
- key_material = tor_malloc(20+key_out_len);
- len = crypto_dh_compute_secret(dh, challenge+16, DH_KEY_LEN,
- key_material, 20+key_out_len);
- if (len < 0)
- goto err;
- /* send back H(K|0) as proof that we learned K. */
- memcpy(handshake_reply_out+DH_KEY_LEN, key_material, 20);
- /* use the rest of the key material for our shared keys, digests, etc */
- memcpy(key_out, key_material+20, key_out_len);
- #ifdef DEBUG_ONION_SKINS
- printf("Server: key material:");
- PA(buf, DH_KEY_LEN);
- puts("");
- printf("Server: keys out:");
- PA(key_out, key_out_len);
- puts("");
- #endif
- tor_free(key_material);
- crypto_free_cipher_env(cipher);
- crypto_dh_free(dh);
- return 0;
- err:
- tor_free(key_material);
- if (cipher) crypto_free_cipher_env(cipher);
- if (dh) crypto_dh_free(dh);
- return -1;
- }
- /* Finish the client side of the DH handshake.
- * Given the 128 byte DH reply + 20 byte hash as generated by
- * onion_skin_server_handshake and the handshake state generated by
- * onion_skin_create, verify H(K) with the first 20 bytes of shared
- * key material, then generate key_out_len more bytes of shared key
- * material and store them in key_out.
- *
- * After the invocation, call crypto_dh_free on handshake_state.
- */
- int
- onion_skin_client_handshake(crypto_dh_env_t *handshake_state,
- char *handshake_reply, /* Must be ONIONSKIN_REPLY_LEN bytes */
- char *key_out,
- int key_out_len)
- {
- int len;
- char *key_material=NULL;
- assert(crypto_dh_get_bytes(handshake_state) == DH_KEY_LEN);
- #ifdef DEBUG_ONION_SKINS
- printf("Client: server g^y:");
- PA(handshake_reply+0,3);
- printf("...");
- PA(handshake_reply+125,3);
- puts("");
- #endif
- key_material = tor_malloc(20+key_out_len);
- len = crypto_dh_compute_secret(handshake_state, handshake_reply, DH_KEY_LEN,
- key_material, 20+key_out_len);
- if (len < 0)
- return -1;
- if(memcmp(key_material, handshake_reply+DH_KEY_LEN, 20)) {
- /* H(K) does *not* match. Something fishy. */
- tor_free(key_material);
- log_fn(LOG_WARN,"Digest DOES NOT MATCH on onion handshake. Bug or attack.");
- return -1;
- }
- /* use the rest of the key material for our shared keys, digests, etc */
- memcpy(key_out, key_material+20, key_out_len);
- #ifdef DEBUG_ONION_SKINS
- printf("Client: keys out:");
- PA(key_out, key_out_len);
- puts("");
- #endif
- tor_free(key_material);
- return 0;
- }
- /*
- Local Variables:
- mode:c
- indent-tabs-mode:nil
- c-basic-offset:2
- End:
- */
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