/* This file is part of GNUnet. (C) 2010, 2012 Christian Grothoff GNUnet is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, 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 General Public License for more details. You should have received a copy of the GNU General Public License along with GNUnet; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /** * @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_mesh_service.h" #include "gnunet_tun_lib.h" #include "gnunet_vpn_service.h" #include "gnunet_statistics_service.h" #include "gnunet_applications.h" /** * After how long do we time out if we could not get an IP from VPN or MESH? */ #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) /** * 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; }; /** * State we keep for a request that is going out via MESH. */ struct RequestContext { /** * We keep these in a DLL. */ struct RequestContext *next; /** * We keep these in a DLL. */ struct RequestContext *prev; /** * Handle for interaction with DNS service. */ struct GNUNET_DNS_RequestHandle *rh; /** * Message we're sending out via MESH, allocated at the * end of this struct. */ const struct GNUNET_MessageHeader *mesh_message; /** * Task used to abort this operation with timeout. */ GNUNET_SCHEDULER_TaskIdentifier timeout_task; /** * ID of the original DNS request (used to match the reply). */ uint16_t dns_id; /** * GNUNET_NO if this request is still in the transmit_queue, * GNUNET_YES if we are in the receive_queue. */ int16_t was_transmitted; }; /** * 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 MESH service */ static struct GNUNET_MESH_Handle *mesh_handle; /** * Tunnel we use for DNS requests over MESH. */ static struct GNUNET_MESH_Tunnel *mesh_tunnel; /** * Active transmission request with MESH (or NULL). */ static struct GNUNET_MESH_TransmitHandle *mesh_th; /** * Head of DLL of requests to be transmitted to mesh_tunnel. */ static struct RequestContext *transmit_queue_head; /** * Tail of DLL of requests to be transmitted to mesh_tunnel. */ static struct RequestContext *transmit_queue_tail; /** * Head of DLL of requests waiting for a response. */ static struct RequestContext *receive_queue_head; /** * Tail of DLL of requests waiting for a response. */ static struct RequestContext *receive_queue_tail; /** * 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; /** * Are we doing IPv4-pt? */ static int ipv4_pt; /** * Are we doing IPv6-pt? */ static int ipv6_pt; /** * Are we tunneling DNS queries? */ static int dns_tunnel; /** * Number of DNS exit peers we currently have in the mesh tunnel. * Used to see if using the mesh tunnel makes any sense right now. */ static unsigned int dns_exit_available; /** * 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); memcpy (rc->rec->data.raw.data, address, sizeof (struct in_addr)); break; case GNUNET_DNSPARSER_TYPE_AAAA: GNUNET_assert (AF_INET6 == af); 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 tunnel * 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_NO /* nac */, 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;ioffset = 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 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;ianswers, 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_malloc (sizeof (struct ReplyContext)); rc->rh = rh; rc->dns = dns; rc->offset = 0; rc->group = ANSWERS; submit_request (rc); } /** * Transmit a DNS request via MESH and move the request * handle to the receive queue. * * @param cls NULL * @param size number of bytes available in buf * @param buf where to copy the message * @return number of bytes written to buf */ static size_t transmit_dns_request_to_mesh (void *cls, size_t size, void *buf) { struct RequestContext *rc; size_t mlen; mesh_th = NULL; if (NULL == (rc = transmit_queue_head)) return 0; mlen = ntohs (rc->mesh_message->size); if (mlen > size) { mesh_th = GNUNET_MESH_notify_transmit_ready (mesh_tunnel, GNUNET_NO, 0, TIMEOUT, NULL, mlen, &transmit_dns_request_to_mesh, NULL); return 0; } GNUNET_assert (GNUNET_NO == rc->was_transmitted); memcpy (buf, rc->mesh_message, mlen); GNUNET_CONTAINER_DLL_remove (transmit_queue_head, transmit_queue_tail, rc); rc->was_transmitted = GNUNET_YES; GNUNET_CONTAINER_DLL_insert (receive_queue_head, receive_queue_tail, rc); rc = transmit_queue_head; if (NULL != rc) mesh_th = GNUNET_MESH_notify_transmit_ready (mesh_tunnel, GNUNET_NO, 0, TIMEOUT, NULL, ntohs (rc->mesh_message->size), &transmit_dns_request_to_mesh, NULL); return mlen; } /** * Task run if the time to answer a DNS request via MESH is over. * * @param cls the 'struct RequestContext' to abort * @param tc scheduler context */ static void timeout_request (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) { struct RequestContext *rc = cls; if (rc->was_transmitted) GNUNET_CONTAINER_DLL_remove (receive_queue_head, receive_queue_tail, rc); else GNUNET_CONTAINER_DLL_remove (transmit_queue_head, transmit_queue_tail, rc); GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests dropped (timeout)"), 1, GNUNET_NO); GNUNET_DNS_request_drop (rc->rh); GNUNET_free (rc); } /** * This function is called *before* the DNS request has been * given to a "local" DNS resolver. Tunneling for DNS requests * was enabled, so we now need to send the request via some MESH * tunnel 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; size_t mlen; struct GNUNET_MessageHeader hdr; struct GNUNET_TUN_DnsHeader dns; 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 mesh tunnel 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; } memcpy (&dns, request, sizeof (dns)); GNUNET_assert (NULL != mesh_tunnel); mlen = sizeof (struct GNUNET_MessageHeader) + request_length; rc = GNUNET_malloc (sizeof (struct RequestContext) + mlen); rc->rh = rh; rc->mesh_message = (const struct GNUNET_MessageHeader*) &rc[1]; rc->timeout_task = GNUNET_SCHEDULER_add_delayed (TIMEOUT, &timeout_request, rc); rc->dns_id = dns.id; hdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_DNS_TO_INTERNET); hdr.size = htons (mlen); memcpy (&rc[1], &hdr, sizeof (struct GNUNET_MessageHeader)); memcpy (&(((char*)&rc[1])[sizeof (struct GNUNET_MessageHeader)]), request, request_length); GNUNET_CONTAINER_DLL_insert_tail (transmit_queue_head, transmit_queue_tail, rc); if (NULL == mesh_th) mesh_th = GNUNET_MESH_notify_transmit_ready (mesh_tunnel, GNUNET_NO, 0, TIMEOUT, NULL, mlen, &transmit_dns_request_to_mesh, NULL); } /** * Process a request via mesh to perform a DNS query. * * @param cls closure, NULL * @param tunnel connection to the other end * @param tunnel_ctx pointer to our 'struct TunnelState *' * @param sender who sent the message * @param message the actual message * @param atsi performance data for the connection * @return GNUNET_OK to keep the connection open, * GNUNET_SYSERR to close it (signal serious error) */ static int receive_dns_response (void *cls GNUNET_UNUSED, struct GNUNET_MESH_Tunnel *tunnel, void **tunnel_ctx, const struct GNUNET_PeerIdentity *sender GNUNET_UNUSED, const struct GNUNET_MessageHeader *message, const struct GNUNET_ATS_Information *atsi GNUNET_UNUSED) { struct GNUNET_TUN_DnsHeader dns; size_t mlen; struct RequestContext *rc; mlen = ntohs (message->size); mlen -= sizeof (struct GNUNET_MessageHeader); if (mlen < sizeof (struct GNUNET_TUN_DnsHeader)) { GNUNET_break_op (0); return GNUNET_SYSERR; } memcpy (&dns, &message[1], sizeof (dns)); for (rc = receive_queue_head; NULL != rc; rc = rc->next) { GNUNET_assert (GNUNET_YES == rc->was_transmitted); if (dns.id == rc->dns_id) { GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS replies received"), 1, GNUNET_NO); GNUNET_DNS_request_answer (rc->rh, mlen, (const void*) &message[1]); GNUNET_CONTAINER_DLL_remove (receive_queue_head, receive_queue_tail, rc); GNUNET_SCHEDULER_cancel (rc->timeout_task); GNUNET_free (rc); return GNUNET_OK; } } GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS replies dropped (too late?)"), 1, GNUNET_NO); return GNUNET_OK; } /** * The MESH DNS tunnel went down. Abort all pending DNS * requests (we're unlikely to get an answer in time). */ static void abort_all_requests () { struct RequestContext *rc; while (NULL != (rc = receive_queue_head)) { GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests aborted (tunnel down)"), 1, GNUNET_NO); GNUNET_CONTAINER_DLL_remove (receive_queue_head, receive_queue_tail, rc); GNUNET_DNS_request_drop (rc->rh); GNUNET_SCHEDULER_cancel (rc->timeout_task); GNUNET_free (rc); } while (NULL != (rc = transmit_queue_head)) { GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests aborted (tunnel down)"), 1, GNUNET_NO); GNUNET_CONTAINER_DLL_remove (transmit_queue_head, transmit_queue_tail, rc); GNUNET_DNS_request_drop (rc->rh); GNUNET_SCHEDULER_cancel (rc->timeout_task); GNUNET_free (rc); } } /** * Method called whenever a peer has disconnected from the tunnel. * * @param cls closure * @param peer peer identity the tunnel stopped working with */ static void mesh_disconnect_handler (void *cls, const struct GNUNET_PeerIdentity * peer) { GNUNET_assert (dns_exit_available > 0); dns_exit_available--; if (0 == dns_exit_available) { if (NULL != mesh_th) { GNUNET_MESH_notify_transmit_ready_cancel (mesh_th); mesh_th = NULL; } abort_all_requests (); } } /** * Method called whenever a peer has connected to the tunnel. * * @param cls closure * @param peer peer identity the tunnel was created to, NULL on timeout * @param atsi performance data for the connection */ static void mesh_connect_handler (void *cls, const struct GNUNET_PeerIdentity * peer, const struct GNUNET_ATS_Information * atsi) { dns_exit_available++; } /** * Function scheduled as very last function, cleans up after us */ static void cleanup (void *cls GNUNET_UNUSED, const struct GNUNET_SCHEDULER_TaskContext *tskctx) { GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Protocol translation daemon is shutting down now\n"); if (vpn_handle != NULL) { GNUNET_VPN_disconnect (vpn_handle); vpn_handle = NULL; } if (NULL != mesh_th) { GNUNET_MESH_notify_transmit_ready_cancel (mesh_th); mesh_th = NULL; } if (NULL != mesh_tunnel) { GNUNET_MESH_tunnel_destroy (mesh_tunnel); mesh_tunnel = NULL; } if (mesh_handle != NULL) { GNUNET_MESH_disconnect (mesh_handle); mesh_handle = NULL; } abort_all_requests (); if (dns_post_handle != NULL) { GNUNET_DNS_disconnect (dns_post_handle); dns_post_handle = NULL; } if (dns_pre_handle != NULL) { GNUNET_DNS_disconnect (dns_pre_handle); dns_pre_handle = NULL; } if (stats != NULL) { GNUNET_STATISTICS_destroy (stats, GNUNET_YES); stats = NULL; } } /** * @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_) { 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_tunnel = GNUNET_CONFIGURATION_get_value_yesno (cfg, "pt", "TUNNEL_DNS"); if (! (ipv4_pt || ipv6_pt || dns_tunnel)) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _("No useful service enabled. Exiting.\n")); GNUNET_SCHEDULER_shutdown (); return; } GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL, &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_tunnel) { static struct GNUNET_MESH_MessageHandler mesh_handlers[] = { {&receive_dns_response, GNUNET_MESSAGE_TYPE_VPN_DNS_FROM_INTERNET, 0}, {NULL, 0, 0} }; static GNUNET_MESH_ApplicationType mesh_types[] = { GNUNET_APPLICATION_TYPE_END }; 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; } mesh_handle = GNUNET_MESH_connect (cfg, 1, NULL, NULL, NULL, mesh_handlers, mesh_types); if (NULL == mesh_handle) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _("Failed to connect to %s service. Exiting.\n"), "MESH"); GNUNET_SCHEDULER_shutdown (); return; } mesh_tunnel = GNUNET_MESH_tunnel_create (mesh_handle, NULL, &mesh_connect_handler, &mesh_disconnect_handler, NULL); GNUNET_MESH_peer_request_connect_by_type (mesh_tunnel, GNUNET_APPLICATION_TYPE_INTERNET_RESOLVER); } } /** * 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 }; return (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; } /* end of gnunet-daemon-pt.c */