/* This file is part of GNUnet. Copyright (C) 2010, 2012, 2017 Christian Grothoff GNUnet is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see . SPDX-License-Identifier: AGPL3.0-or-later */ /** * @file pt/gnunet-daemon-pt.c * @brief tool to manipulate DNS and VPN services to perform protocol translation (IPvX over GNUnet) * @author Christian Grothoff */ #include "platform.h" #include "gnunet_util_lib.h" #include "gnunet_dns_service.h" #include "gnunet_dnsparser_lib.h" #include "gnunet_cadet_service.h" #include "gnunet_tun_lib.h" #include "gnunet_dht_service.h" #include "gnunet_vpn_service.h" #include "gnunet_statistics_service.h" #include "gnunet_applications.h" #include "block_dns.h" /** * After how long do we time out if we could not get an IP from VPN or CADET? */ #define TIMEOUT GNUNET_TIME_UNIT_MINUTES /** * How many bytes of payload do we allow at most for a DNS reply? * Given that this is pretty much limited to loopback, we can be * pretty high (Linux loopback defaults to 16k, most local UDP packets * should survive up to 9k (NFS), so 8k should be pretty safe in * general). */ #define MAX_DNS_SIZE (8 * 1024) /** * How many channels do we open at most at the same time? */ #define MAX_OPEN_TUNNELS 4 /** * Which group of DNS records are we currently processing? */ enum RequestGroup { /** * DNS answers */ ANSWERS = 0, /** * DNS authority records */ AUTHORITY_RECORDS = 1, /** * DNS additional records */ ADDITIONAL_RECORDS = 2, /** * We're done processing. */ END = 3 }; /** * Information tracked per DNS reply that we are processing. */ struct ReplyContext { /** * Handle to submit the final result. */ struct GNUNET_DNS_RequestHandle *rh; /** * DNS packet that is being modified. */ struct GNUNET_DNSPARSER_Packet *dns; /** * Active redirection request with the VPN. */ struct GNUNET_VPN_RedirectionRequest *rr; /** * Record for which we have an active redirection request. */ struct GNUNET_DNSPARSER_Record *rec; /** * Offset in the current record group that is being modified. */ unsigned int offset; /** * Group that is being modified */ enum RequestGroup group; }; /** * Handle to a peer that advertised that it is willing to serve * as a DNS exit. We try to keep a few channels open and a few * peers in reserve. */ struct CadetExit { /** * Kept in a DLL. */ struct CadetExit *next; /** * Kept in a DLL. */ struct CadetExit *prev; /** * Channel we use for DNS requests over CADET, NULL if we did * not initialze a channel to this peer yet. */ struct GNUNET_CADET_Channel *cadet_channel; /** * At what time did the peer's advertisement expire? */ struct GNUNET_TIME_Absolute expiration; /** * Head of DLL of requests waiting for a response. */ struct RequestContext *receive_queue_head; /** * Tail of DLL of requests waiting for a response. */ struct RequestContext *receive_queue_tail; /** * Identity of the peer that is providing the exit for us. */ struct GNUNET_PeerIdentity peer; /** * How many DNS requests did we transmit via this channel? */ unsigned int num_transmitted; /** * How many DNS requests were answered via this channel? */ unsigned int num_answered; /** * Size of the window, 0 if we are busy. */ /* unsigned */ int idle; }; /** * State we keep for a request that is going out via CADET. */ struct RequestContext { /** * We keep these in a DLL. */ struct RequestContext *next; /** * We keep these in a DLL. */ struct RequestContext *prev; /** * Exit that was chosen for this request. */ struct CadetExit *exit; /** * Handle for interaction with DNS service. */ struct GNUNET_DNS_RequestHandle *rh; /** * Envelope with the request we are transmitting. */ struct GNUNET_MQ_Envelope *env; /** * Task used to abort this operation with timeout. */ struct GNUNET_SCHEDULER_Task *timeout_task; /** * Length of the request message that follows this struct. */ uint16_t mlen; /** * ID of the original DNS request (used to match the reply). */ uint16_t dns_id; }; /** * Head of DLL of cadet exits. Cadet exits with an open channel are * always at the beginning (so we do not have to traverse the entire * list to find them). */ static struct CadetExit *exit_head; /** * Tail of DLL of cadet exits. */ static struct CadetExit *exit_tail; /** * The handle to the configuration used throughout the process */ static const struct GNUNET_CONFIGURATION_Handle *cfg; /** * The handle to the VPN */ static struct GNUNET_VPN_Handle *vpn_handle; /** * The handle to the CADET service */ static struct GNUNET_CADET_Handle *cadet_handle; /** * Statistics. */ static struct GNUNET_STATISTICS_Handle *stats; /** * The handle to DNS post-resolution modifications. */ static struct GNUNET_DNS_Handle *dns_post_handle; /** * The handle to DNS pre-resolution modifications. */ static struct GNUNET_DNS_Handle *dns_pre_handle; /** * Handle to access the DHT. */ static struct GNUNET_DHT_Handle *dht; /** * Our DHT GET operation to find DNS exits. */ static struct GNUNET_DHT_GetHandle *dht_get; /** * Are we doing IPv4-pt? */ static int ipv4_pt; /** * Are we doing IPv6-pt? */ static int ipv6_pt; /** * Are we channeling DNS queries? */ static int dns_channel; /** * Number of DNS exit peers we currently have in the cadet channel. * Used to see if using the cadet channel makes any sense right now, * as well as to decide if we should open new channels. */ static unsigned int dns_exit_available; /** * We are short on cadet exits, try to open another one. */ static void try_open_exit (void); /** * Compute the weight of the given exit. The higher the weight, * the more likely it will be that the channel will be chosen. * A weigt of zero means that we should close the channel as it * is so bad, that we should not use it. * * @param exit exit to calculate the weight for * @return weight of the channel */ static uint32_t get_channel_weight (struct CadetExit *exit) { uint32_t dropped; uint32_t drop_percent; uint32_t good_percent; GNUNET_assert (exit->num_transmitted >= exit->num_answered); dropped = exit->num_transmitted - exit->num_answered; if (exit->num_transmitted > 0) drop_percent = (uint32_t) ((100LL * dropped) / exit->num_transmitted); else drop_percent = 50; /* no data */ if ((exit->num_transmitted > 20) && (drop_percent > 25)) return 0; /* statistically significant, and > 25% loss, die */ good_percent = 100 - drop_percent; GNUNET_assert (0 != good_percent); if (UINT32_MAX / good_percent / good_percent < exit->num_transmitted) return UINT32_MAX; /* formula below would overflow */ return 1 + good_percent * good_percent * exit->num_transmitted; } /** * Choose a cadet exit for a DNS request. We try to use a channel * that is reliable and currently available. All existing * channels are given a base weight of 1, plus a score relating * to the total number of queries answered in relation to the * total number of queries we sent to that channel. That * score is doubled if the channel is currently idle. * * @return NULL if no exit is known, otherwise the * exit that we should use to queue a message with */ static struct CadetExit * choose_exit () { struct CadetExit *pos; uint64_t total_transmitted; uint64_t selected_offset; uint32_t channel_weight; total_transmitted = 0; for (pos = exit_head; NULL != pos; pos = pos->next) { if (NULL == pos->cadet_channel) break; channel_weight = get_channel_weight (pos); total_transmitted += channel_weight; /* double weight for idle channels */ if (0 != pos->idle) total_transmitted += channel_weight; } if (0 == total_transmitted) { /* no channels available, or only a very bad one... */ return exit_head; } selected_offset = GNUNET_CRYPTO_random_u64 (GNUNET_CRYPTO_QUALITY_WEAK, total_transmitted); total_transmitted = 0; for (pos = exit_head; NULL != pos; pos = pos->next) { if (NULL == pos->cadet_channel) break; channel_weight = get_channel_weight (pos); total_transmitted += channel_weight; /* double weight for idle channels */ if (0 != pos->idle) total_transmitted += channel_weight; if (total_transmitted > selected_offset) return pos; } GNUNET_break (0); return NULL; } /** * We're done modifying all records in the response. Submit the reply * and free the resources of the rc. * * @param rc context to process */ static void finish_request (struct ReplyContext *rc) { char *buf; size_t buf_len; if (GNUNET_SYSERR == GNUNET_DNSPARSER_pack (rc->dns, MAX_DNS_SIZE, &buf, &buf_len)) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Failed to pack DNS request. Dropping.\n")); GNUNET_DNS_request_drop (rc->rh); } else { GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests mapped to VPN"), 1, GNUNET_NO); GNUNET_DNS_request_answer (rc->rh, buf_len, buf); GNUNET_free (buf); } GNUNET_DNSPARSER_free_packet (rc->dns); GNUNET_free (rc); } /** * Process the next record of the given request context. * When done, submit the reply and free the resources of * the rc. * * @param rc context to process */ static void submit_request (struct ReplyContext *rc); /** * Callback invoked from the VPN service once a redirection is * available. Provides the IP address that can now be used to * reach the requested destination. We substitute the active * record and then continue with 'submit_request' to look at * the other records. * * @param cls our `struct ReplyContext` * @param af address family, AF_INET or AF_INET6; AF_UNSPEC on error; * will match 'result_af' from the request * @param address IP address (struct in_addr or struct in_addr6, depending on 'af') * that the VPN allocated for the redirection; * traffic to this IP will now be redirected to the * specified target peer; NULL on error */ static void vpn_allocation_callback (void *cls, int af, const void *address) { struct ReplyContext *rc = cls; rc->rr = NULL; if (af == AF_UNSPEC) { GNUNET_DNS_request_drop (rc->rh); GNUNET_DNSPARSER_free_packet (rc->dns); GNUNET_free (rc); return; } GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS records modified"), 1, GNUNET_NO); switch (rc->rec->type) { case GNUNET_DNSPARSER_TYPE_A: GNUNET_assert (AF_INET == af); GNUNET_memcpy (rc->rec->data.raw.data, address, sizeof(struct in_addr)); break; case GNUNET_DNSPARSER_TYPE_AAAA: GNUNET_assert (AF_INET6 == af); GNUNET_memcpy (rc->rec->data.raw.data, address, sizeof(struct in6_addr)); break; default: GNUNET_assert (0); return; } rc->rec = NULL; submit_request (rc); } /** * Modify the given DNS record by asking VPN to create a channel * to the given address. When done, continue with submitting * other records from the request context ('submit_request' is * our continuation). * * @param rc context to process * @param rec record to modify */ static void modify_address (struct ReplyContext *rc, struct GNUNET_DNSPARSER_Record *rec) { int af; switch (rec->type) { case GNUNET_DNSPARSER_TYPE_A: af = AF_INET; GNUNET_assert (rec->data.raw.data_len == sizeof(struct in_addr)); break; case GNUNET_DNSPARSER_TYPE_AAAA: af = AF_INET6; GNUNET_assert (rec->data.raw.data_len == sizeof(struct in6_addr)); break; default: GNUNET_assert (0); return; } rc->rec = rec; rc->rr = GNUNET_VPN_redirect_to_ip (vpn_handle, af, af, rec->data.raw.data, GNUNET_TIME_relative_to_absolute ( TIMEOUT), &vpn_allocation_callback, rc); } /** * Process the next record of the given request context. * When done, submit the reply and free the resources of * the rc. * * @param rc context to process */ static void submit_request (struct ReplyContext *rc) { struct GNUNET_DNSPARSER_Record *ra; unsigned int ra_len; unsigned int i; while (1) { switch (rc->group) { case ANSWERS: ra = rc->dns->answers; ra_len = rc->dns->num_answers; break; case AUTHORITY_RECORDS: ra = rc->dns->authority_records; ra_len = rc->dns->num_authority_records; break; case ADDITIONAL_RECORDS: ra = rc->dns->additional_records; ra_len = rc->dns->num_additional_records; break; case END: finish_request (rc); return; default: GNUNET_assert (0); } for (i = rc->offset; i < ra_len; i++) { switch (ra[i].type) { case GNUNET_DNSPARSER_TYPE_A: if (ipv4_pt) { rc->offset = i + 1; modify_address (rc, &ra[i]); return; } break; case GNUNET_DNSPARSER_TYPE_AAAA: if (ipv6_pt) { rc->offset = i + 1; modify_address (rc, &ra[i]); return; } break; } } rc->group++; } } /** * Test if any of the given records need protocol-translation work. * * @param ra array of records * @param ra_len number of entries in @a ra * @return #GNUNET_YES if any of the given records require protocol-translation */ static int work_test (const struct GNUNET_DNSPARSER_Record *ra, unsigned int ra_len) { unsigned int i; for (i = 0; i < ra_len; i++) { switch (ra[i].type) { case GNUNET_DNSPARSER_TYPE_A: if (ipv4_pt) return GNUNET_YES; break; case GNUNET_DNSPARSER_TYPE_AAAA: if (ipv6_pt) return GNUNET_YES; break; } } return GNUNET_NO; } /** * This function is called AFTER we got an IP address for a * DNS request. Now, the PT daemon has the chance to substitute * the IP address with one from the VPN range to channel requests * destined for this IP address via VPN and CADET. * * @param cls closure * @param rh request handle to user for reply * @param request_length number of bytes in request * @param request udp payload of the DNS request */ static void dns_post_request_handler (void *cls, struct GNUNET_DNS_RequestHandle *rh, size_t request_length, const char *request) { struct GNUNET_DNSPARSER_Packet *dns; struct ReplyContext *rc; int work; GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS replies intercepted"), 1, GNUNET_NO); dns = GNUNET_DNSPARSER_parse (request, request_length); if (NULL == dns) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Failed to parse DNS request. Dropping.\n")); GNUNET_DNS_request_drop (rh); return; } work = GNUNET_NO; work |= work_test (dns->answers, dns->num_answers); work |= work_test (dns->authority_records, dns->num_authority_records); work |= work_test (dns->additional_records, dns->num_additional_records); if (! work) { GNUNET_DNS_request_forward (rh); GNUNET_DNSPARSER_free_packet (dns); return; } rc = GNUNET_new (struct ReplyContext); rc->rh = rh; rc->dns = dns; rc->offset = 0; rc->group = ANSWERS; submit_request (rc); } /** * Task run if the time to answer a DNS request via CADET is over. * * @param cls the `struct RequestContext` to abort */ static void timeout_request (void *cls) { struct RequestContext *rc = cls; struct CadetExit *exit = rc->exit; GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests dropped (timeout)"), 1, GNUNET_NO); GNUNET_DNS_request_drop (rc->rh); GNUNET_free (rc); if ((0 == get_channel_weight (exit)) && (NULL == exit->receive_queue_head)) { /* this straw broke the camel's back: this channel now has such a low score that it will not be used; close it! */ GNUNET_CADET_channel_destroy (exit->cadet_channel); exit->cadet_channel = NULL; GNUNET_CONTAINER_DLL_remove (exit_head, exit_tail, exit); GNUNET_CONTAINER_DLL_insert_tail (exit_head, exit_tail, exit); /* go back to semi-innocent: mark as not great, but avoid a prohibitively negative score (see #get_channel_weight(), which checks for a certain minimum number of transmissions before making up an opinion) */exit->num_transmitted = 5; exit->num_answered = 0; dns_exit_available--; /* now try to open an alternative exit */ try_open_exit (); } } /** * This function is called *before* the DNS request has been * given to a "local" DNS resolver. Channeling for DNS requests * was enabled, so we now need to send the request via some CADET * channel to a DNS EXIT for resolution. * * @param cls closure * @param rh request handle to user for reply * @param request_length number of bytes in request * @param request udp payload of the DNS request */ static void dns_pre_request_handler (void *cls, struct GNUNET_DNS_RequestHandle *rh, size_t request_length, const char *request) { struct RequestContext *rc; struct GNUNET_MQ_Envelope *env; struct GNUNET_MessageHeader *hdr; struct GNUNET_TUN_DnsHeader dns; struct CadetExit *exit; GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests intercepted"), 1, GNUNET_NO); if (0 == dns_exit_available) { GNUNET_STATISTICS_update (stats, gettext_noop ( "# DNS requests dropped (DNS cadet channel down)"), 1, GNUNET_NO); GNUNET_DNS_request_drop (rh); return; } if (request_length < sizeof(dns)) { GNUNET_STATISTICS_update (stats, gettext_noop ( "# DNS requests dropped (malformed)"), 1, GNUNET_NO); GNUNET_DNS_request_drop (rh); return; } exit = choose_exit (); GNUNET_assert (NULL != exit); GNUNET_assert (NULL != exit->cadet_channel); env = GNUNET_MQ_msg_extra (hdr, request_length, GNUNET_MESSAGE_TYPE_VPN_DNS_TO_INTERNET); GNUNET_memcpy (&hdr[1], request, request_length); rc = GNUNET_new (struct RequestContext); rc->exit = exit; rc->rh = rh; rc->timeout_task = GNUNET_SCHEDULER_add_delayed (TIMEOUT, &timeout_request, rc); GNUNET_memcpy (&dns, request, sizeof(dns)); rc->dns_id = dns.id; rc->env = env; GNUNET_CONTAINER_DLL_remove (exit->receive_queue_head, exit->receive_queue_tail, rc); if (0 < exit->idle) exit->idle--; exit->num_transmitted++; GNUNET_MQ_send (GNUNET_CADET_get_mq (exit->cadet_channel), GNUNET_MQ_env_copy (env)); } GNUNET_NETWORK_STRUCT_BEGIN /** * Message with a DNS response. */ struct DnsResponseMessage { /** * GNUnet header, of type #GNUNET_MESSAGE_TYPE_VPN_DNS_FROM_INTERNET */ struct GNUNET_MessageHeader header; /** * DNS header. */ struct GNUNET_TUN_DnsHeader dns; /* Followed by more DNS payload */ }; GNUNET_NETWORK_STRUCT_END /** * Process a request via cadet to perform a DNS query. * * @param cls the `struct CadetExit` which got the message * @param msg the actual message * @return #GNUNET_OK to keep the connection open, * #GNUNET_SYSERR to close it (signal serious error) */ static int check_dns_response (void *cls, const struct DnsResponseMessage *msg) { return GNUNET_OK; /* all OK */ } /** * Process a request via cadet to perform a DNS query. * * @param cls the `struct CadetExit` which got the message * @param msg the actual message */ static void handle_dns_response (void *cls, const struct DnsResponseMessage *msg) { struct CadetExit *exit = cls; size_t mlen; struct RequestContext *rc; mlen = ntohs (msg->header.size) - sizeof(*msg); for (rc = exit->receive_queue_head; NULL != rc; rc = rc->next) { if (msg->dns.id == rc->dns_id) { GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS replies received"), 1, GNUNET_NO); GNUNET_DNS_request_answer (rc->rh, mlen + sizeof(struct GNUNET_TUN_DnsHeader), (const void *) &msg->dns); GNUNET_CONTAINER_DLL_remove (exit->receive_queue_head, exit->receive_queue_tail, rc); GNUNET_SCHEDULER_cancel (rc->timeout_task); GNUNET_MQ_discard (rc->env); GNUNET_free (rc); exit->num_answered++; return; } } GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS replies dropped (too late?)"), 1, GNUNET_NO); } /** * Abort all pending DNS requests with the given cadet exit. * * @param exit cadet exit to abort requests for */ static void abort_all_requests (struct CadetExit *exit) { struct RequestContext *rc; while (NULL != (rc = exit->receive_queue_head)) { GNUNET_CONTAINER_DLL_remove (exit->receive_queue_head, exit->receive_queue_tail, rc); GNUNET_DNS_request_drop (rc->rh); GNUNET_SCHEDULER_cancel (rc->timeout_task); GNUNET_MQ_discard (rc->env); GNUNET_free (rc); } } /** * Function scheduled as very last function, cleans up after us * * @param cls closure, NULL */ static void cleanup (void *cls) { struct CadetExit *exit; GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Protocol translation daemon is shutting down now\n"); if (NULL != vpn_handle) { GNUNET_VPN_disconnect (vpn_handle); vpn_handle = NULL; } while (NULL != (exit = exit_head)) { GNUNET_CONTAINER_DLL_remove (exit_head, exit_tail, exit); if (NULL != exit->cadet_channel) { GNUNET_CADET_channel_destroy (exit->cadet_channel); exit->cadet_channel = NULL; } abort_all_requests (exit); GNUNET_free (exit); } if (NULL != cadet_handle) { GNUNET_CADET_disconnect (cadet_handle); cadet_handle = NULL; } if (NULL != dns_post_handle) { GNUNET_DNS_disconnect (dns_post_handle); dns_post_handle = NULL; } if (NULL != dns_pre_handle) { GNUNET_DNS_disconnect (dns_pre_handle); dns_pre_handle = NULL; } if (NULL != stats) { GNUNET_STATISTICS_destroy (stats, GNUNET_YES); stats = NULL; } if (NULL != dht_get) { GNUNET_DHT_get_stop (dht_get); dht_get = NULL; } if (NULL != dht) { GNUNET_DHT_disconnect (dht); dht = NULL; } } /** * Function called whenever a channel is destroyed. Should clean up * the associated state and attempt to build a new one. * * It must NOT call #GNUNET_CADET_channel_destroy on the channel. * * @param cls closure (the `struct CadetExit` set from #GNUNET_CADET_connect) * @param channel connection to the other end (henceforth invalid) * @param channel_ctx place where local state associated * with the channel is stored */ static void cadet_channel_end_cb (void *cls, const struct GNUNET_CADET_Channel *channel) { struct CadetExit *exit = cls; struct CadetExit *alt; struct RequestContext *rc; exit->cadet_channel = NULL; dns_exit_available--; /* open alternative channels */ /* our channel is now closed, move our requests to an alternative channel */ alt = choose_exit (); while (NULL != (rc = exit->receive_queue_head)) { GNUNET_CONTAINER_DLL_remove (exit->receive_queue_head, exit->receive_queue_tail, rc); rc->exit = alt; GNUNET_CONTAINER_DLL_insert (alt->receive_queue_head, alt->receive_queue_tail, rc); GNUNET_MQ_send (GNUNET_CADET_get_mq (alt->cadet_channel), GNUNET_MQ_env_copy (rc->env)); } try_open_exit (); } /** * Function called whenever a channel has excess capacity. * * @param cls the `struct CadetExit` * @param channel connection to the other end * @param window_size how much capacity do we have */ static void channel_idle_notify_cb (void *cls, const struct GNUNET_CADET_Channel *channel, int window_size) { struct CadetExit *pos = cls; pos->idle = window_size; } /** * We are short on cadet exits, try to open another one. */ static void try_open_exit () { struct CadetExit *pos; uint32_t candidate_count; uint32_t candidate_selected; struct GNUNET_HashCode port; GNUNET_CRYPTO_hash (GNUNET_APPLICATION_PORT_INTERNET_RESOLVER, strlen (GNUNET_APPLICATION_PORT_INTERNET_RESOLVER), &port); candidate_count = 0; for (pos = exit_head; NULL != pos; pos = pos->next) if (NULL == pos->cadet_channel) candidate_count++; if (0 == candidate_count) { GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "No DNS exits available yet.\n"); return; } candidate_selected = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, candidate_count); candidate_count = 0; for (pos = exit_head; NULL != pos; pos = pos->next) if (NULL == pos->cadet_channel) { candidate_count++; if (candidate_selected < candidate_count) { struct GNUNET_MQ_MessageHandler cadet_handlers[] = { GNUNET_MQ_hd_var_size (dns_response, GNUNET_MESSAGE_TYPE_VPN_DNS_FROM_INTERNET, struct DnsResponseMessage, pos), GNUNET_MQ_handler_end () }; /* move to the head of the DLL */ pos->cadet_channel = GNUNET_CADET_channel_create (cadet_handle, pos, &pos->peer, &port, &channel_idle_notify_cb, &cadet_channel_end_cb, cadet_handlers); if (NULL == pos->cadet_channel) { GNUNET_break (0); continue; } GNUNET_CONTAINER_DLL_remove (exit_head, exit_tail, pos); GNUNET_CONTAINER_DLL_insert (exit_head, exit_tail, pos); dns_exit_available++; return; } } GNUNET_assert (NULL == exit_head); } /** * Function called whenever we find an advertisement for a * DNS exit in the DHT. If we don't have a cadet channel, * we should build one; otherwise, we should save the * advertisement for later use. * * @param cls closure * @param exp when will this value expire * @param key key of the result * @param get_path peers on reply path (or NULL if not recorded) * [0] = datastore's first neighbor, [length - 1] = local peer * @param get_path_length number of entries in @a get_path * @param put_path peers on the PUT path (or NULL if not recorded) * [0] = origin, [length - 1] = datastore * @param put_path_length number of entries in @a put_path * @param type type of the result * @param size number of bytes in @a data * @param data pointer to the result data */ static void handle_dht_result (void *cls, struct GNUNET_TIME_Absolute exp, const struct GNUNET_HashCode *key, const struct GNUNET_PeerIdentity *get_path, unsigned int get_path_length, const struct GNUNET_PeerIdentity *put_path, unsigned int put_path_length, enum GNUNET_BLOCK_Type type, size_t size, const void *data) { const struct GNUNET_DNS_Advertisement *ad; struct CadetExit *exit; if (sizeof(struct GNUNET_DNS_Advertisement) != size) { GNUNET_break (0); return; } ad = data; for (exit = exit_head; NULL != exit; exit = exit->next) if (0 == GNUNET_memcmp (&ad->peer, &exit->peer)) break; if (NULL == exit) { exit = GNUNET_new (struct CadetExit); exit->peer = ad->peer; /* channel is closed, so insert at the end */ GNUNET_CONTAINER_DLL_insert_tail (exit_head, exit_tail, exit); } exit->expiration = GNUNET_TIME_absolute_max (exit->expiration, GNUNET_TIME_absolute_ntoh ( ad->expiration_time)); if (dns_exit_available < MAX_OPEN_TUNNELS) try_open_exit (); } /** * @brief Main function that will be run by the scheduler. * * @param cls closure * @param args remaining command-line arguments * @param cfgfile name of the configuration file used (for saving, can be NULL!) * @param cfg_ configuration */ static void run (void *cls, char *const *args GNUNET_UNUSED, const char *cfgfile GNUNET_UNUSED, const struct GNUNET_CONFIGURATION_Handle *cfg_) { struct GNUNET_HashCode dns_key; cfg = cfg_; stats = GNUNET_STATISTICS_create ("pt", cfg); ipv4_pt = GNUNET_CONFIGURATION_get_value_yesno (cfg, "pt", "TUNNEL_IPV4"); ipv6_pt = GNUNET_CONFIGURATION_get_value_yesno (cfg, "pt", "TUNNEL_IPV6"); dns_channel = GNUNET_CONFIGURATION_get_value_yesno (cfg, "pt", "TUNNEL_DNS"); if (! (ipv4_pt || ipv6_pt || dns_channel)) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("No useful service enabled. Exiting.\n")); GNUNET_SCHEDULER_shutdown (); return; } GNUNET_SCHEDULER_add_shutdown (&cleanup, cls); if (ipv4_pt || ipv6_pt) { dns_post_handle = GNUNET_DNS_connect (cfg, GNUNET_DNS_FLAG_POST_RESOLUTION, &dns_post_request_handler, NULL); if (NULL == dns_post_handle) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Failed to connect to %s service. Exiting.\n"), "DNS"); GNUNET_SCHEDULER_shutdown (); return; } vpn_handle = GNUNET_VPN_connect (cfg); if (NULL == vpn_handle) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Failed to connect to %s service. Exiting.\n"), "VPN"); GNUNET_SCHEDULER_shutdown (); return; } } if (dns_channel) { dns_pre_handle = GNUNET_DNS_connect (cfg, GNUNET_DNS_FLAG_PRE_RESOLUTION, &dns_pre_request_handler, NULL); if (NULL == dns_pre_handle) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Failed to connect to %s service. Exiting.\n"), "DNS"); GNUNET_SCHEDULER_shutdown (); return; } cadet_handle = GNUNET_CADET_connect (cfg); if (NULL == cadet_handle) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Failed to connect to %s service. Exiting.\n"), "CADET"); GNUNET_SCHEDULER_shutdown (); return; } dht = GNUNET_DHT_connect (cfg, 1); if (NULL == dht) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Failed to connect to %s service. Exiting.\n"), "DHT"); GNUNET_SCHEDULER_shutdown (); return; } GNUNET_CRYPTO_hash ("dns", strlen ("dns"), &dns_key); dht_get = GNUNET_DHT_get_start (dht, GNUNET_BLOCK_TYPE_DNS, &dns_key, 1, GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE, NULL, 0, &handle_dht_result, NULL); } } /** * The main function * * @param argc number of arguments from the command line * @param argv command line arguments * @return 0 ok, 1 on error */ int main (int argc, char *const *argv) { static const struct GNUNET_GETOPT_CommandLineOption options[] = { GNUNET_GETOPT_OPTION_END }; int ret; if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args (argc, argv, &argc, &argv)) return 2; ret = (GNUNET_OK == GNUNET_PROGRAM_run (argc, argv, "gnunet-daemon-pt", gettext_noop ( "Daemon to run to perform IP protocol translation to GNUnet"), options, &run, NULL)) ? 0 : 1; GNUNET_free ((void *) argv); return ret; } /* end of gnunet-daemon-pt.c */