/* This file is part of GNUnet. Copyright (C) 2012 Christian Grothoff (and other contributing authors) 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 dns/gnunet-service-dns.c * @brief service to intercept and modify DNS queries (and replies) of this system * @author Christian Grothoff * * For "secure" interaction with the legacy DNS system, we permit * replies only to arrive within a 5s window (and they must match * ports, IPs and request IDs). Furthermore, we let the OS pick a * source port, opening up to 128 sockets per address family (IPv4 or * IPv6). Those sockets are closed if they are not in use for 5s * (which means they will be freshly randomized afterwards). For new * requests, we pick a random slot in the array with 128 socket slots * (and re-use an existing socket if the slot is still in use). Thus * each request will be given one of 128 random source ports, and the * 128 random source ports will also change "often" (less often if the * system is very busy, each time if we are mostly idle). At the same * time, the system will never use more than 256 UDP sockets. */ #include "platform.h" #include "gnunet_util_lib.h" #include "gnunet_applications.h" #include "gnunet_constants.h" #include "gnunet_protocols.h" #include "gnunet_signatures.h" #include "dns.h" #include "gnunet_dns_service.h" #include "gnunet_dnsparser_lib.h" #include "gnunet_dnsstub_lib.h" #include "gnunet_statistics_service.h" #include "gnunet_tun_lib.h" /** * Port number for DNS */ #define DNS_PORT 53 /** * Generic logging shorthand */ #define LOG(kind, ...) \ GNUNET_log_from (kind, "dns", __VA_ARGS__); /** * Phases each request goes through. */ enum RequestPhase { /** * Request has just been received. */ RP_INIT, /** * Showing the request to all monitor clients. If * client list is empty, will enter QUERY phase. */ RP_REQUEST_MONITOR, /** * Showing the request to PRE-RESOLUTION clients to find an answer. * If client list is empty, will trigger global DNS request. */ RP_QUERY, /** * Global Internet query is now pending. */ RP_INTERNET_DNS, /** * Client (or global DNS request) has resulted in a response. * Forward to all POST-RESOLUTION clients. If client list is empty, * will enter RESPONSE_MONITOR phase. */ RP_MODIFY, /** * Showing the request to all monitor clients. If * client list is empty, give the result to the hijacker (and be done). */ RP_RESPONSE_MONITOR, /** * Some client has told us to drop the request. */ RP_DROP }; /** * Entry we keep for each client. */ struct ClientRecord { /** * Kept in doubly-linked list. */ struct ClientRecord *next; /** * Kept in doubly-linked list. */ struct ClientRecord *prev; /** * Handle to the client. */ struct GNUNET_SERVER_Client *client; /** * Flags for the client. */ enum GNUNET_DNS_Flags flags; }; /** * Entry we keep for each active request. */ struct RequestRecord { /** * List of clients that still need to see this request (each entry * is set to NULL when the client is done). */ struct ClientRecord **client_wait_list; /** * Payload of the UDP packet (the UDP payload), can be either query * or already the response. */ char *payload; /** * Socket we are using to transmit this request (must match if we receive * a response). */ struct GNUNET_DNSSTUB_RequestSocket *rs; /** * Source address of the original request (for sending response). */ struct sockaddr_storage src_addr; /** * Destination address of the original request (for potential use as exit). */ struct sockaddr_storage dst_addr; /** * ID of this request, also basis for hashing. Lowest 16 bit will * be our message ID when doing a global DNS request and our index * into the 'requests' array. */ uint64_t request_id; /** * Number of bytes in payload. */ size_t payload_length; /** * Length of the client wait list. */ unsigned int client_wait_list_length; /** * In which phase this this request? */ enum RequestPhase phase; }; /** * Global return value from 'main'. */ static int global_ret; /** * The configuration to use */ static const struct GNUNET_CONFIGURATION_Handle *cfg; /** * Statistics. */ static struct GNUNET_STATISTICS_Handle *stats; /** * Handle to DNS hijacker helper process ("gnunet-helper-dns"). */ static struct GNUNET_HELPER_Handle *hijacker; /** * Command-line arguments we are giving to the hijacker process. */ static char *helper_argv[7]; /** * Head of DLL of clients we consult. */ static struct ClientRecord *clients_head; /** * Tail of DLL of clients we consult. */ static struct ClientRecord *clients_tail; /** * Our notification context. */ static struct GNUNET_SERVER_NotificationContext *nc; /** * Array of all open requests. */ static struct RequestRecord requests[UINT16_MAX + 1]; /** * Generator for unique request IDs. */ static uint64_t request_id_gen; /** * Handle to the DNS Stub resolver. */ static struct GNUNET_DNSSTUB_Context *dnsstub; /** * We're done processing a DNS request, free associated memory. * * @param rr request to clean up */ static void cleanup_rr (struct RequestRecord *rr) { GNUNET_free_non_null (rr->payload); rr->payload = NULL; rr->payload_length = 0; GNUNET_array_grow (rr->client_wait_list, rr->client_wait_list_length, 0); } /** * Task run during shutdown. * * @param cls unused * @param tc unused */ static void cleanup_task (void *cls GNUNET_UNUSED, const struct GNUNET_SCHEDULER_TaskContext *tc) { unsigned int i; GNUNET_HELPER_stop (hijacker, GNUNET_NO); hijacker = NULL; for (i=0;i<7;i++) GNUNET_free_non_null (helper_argv[i]); for (i=0;i<=UINT16_MAX;i++) cleanup_rr (&requests[i]); GNUNET_SERVER_notification_context_destroy (nc); nc = NULL; if (stats != NULL) { GNUNET_STATISTICS_destroy (stats, GNUNET_NO); stats = NULL; } if (NULL != dnsstub) { GNUNET_DNSSTUB_stop (dnsstub); dnsstub = NULL; } } /** * We're done with some request, finish processing. * * @param rr request send to the network or just clean up. */ static void request_done (struct RequestRecord *rr) { struct GNUNET_MessageHeader *hdr; size_t reply_len; uint16_t source_port; uint16_t destination_port; GNUNET_array_grow (rr->client_wait_list, rr->client_wait_list_length, 0); if (RP_RESPONSE_MONITOR != rr->phase) { /* no response, drop */ LOG (GNUNET_ERROR_TYPE_DEBUG, "Got no response for request %llu, dropping\n", (unsigned long long) rr->request_id); cleanup_rr (rr); return; } LOG (GNUNET_ERROR_TYPE_DEBUG, "Transmitting response for request %llu\n", (unsigned long long) rr->request_id); /* send response via hijacker */ reply_len = sizeof (struct GNUNET_MessageHeader); reply_len += sizeof (struct GNUNET_TUN_Layer2PacketHeader); switch (rr->src_addr.ss_family) { case AF_INET: reply_len += sizeof (struct GNUNET_TUN_IPv4Header); break; case AF_INET6: reply_len += sizeof (struct GNUNET_TUN_IPv6Header); break; default: GNUNET_break (0); cleanup_rr (rr); return; } reply_len += sizeof (struct GNUNET_TUN_UdpHeader); reply_len += rr->payload_length; if (reply_len >= GNUNET_SERVER_MAX_MESSAGE_SIZE) { /* response too big, drop */ GNUNET_break (0); /* how can this be? */ cleanup_rr(rr); return; } { char buf[reply_len] GNUNET_ALIGN; size_t off; struct GNUNET_TUN_IPv4Header ip4; struct GNUNET_TUN_IPv6Header ip6; /* first, GNUnet message header */ hdr = (struct GNUNET_MessageHeader*) buf; hdr->type = htons (GNUNET_MESSAGE_TYPE_DNS_HELPER); hdr->size = htons ((uint16_t) reply_len); off = sizeof (struct GNUNET_MessageHeader); /* first, TUN header */ { struct GNUNET_TUN_Layer2PacketHeader tun; tun.flags = htons (0); if (rr->src_addr.ss_family == AF_INET) tun.proto = htons (ETH_P_IPV4); else tun.proto = htons (ETH_P_IPV6); memcpy (&buf[off], &tun, sizeof (struct GNUNET_TUN_Layer2PacketHeader)); off += sizeof (struct GNUNET_TUN_Layer2PacketHeader); } /* now IP header */ switch (rr->src_addr.ss_family) { case AF_INET: { struct sockaddr_in *src = (struct sockaddr_in *) &rr->src_addr; struct sockaddr_in *dst = (struct sockaddr_in *) &rr->dst_addr; source_port = dst->sin_port; destination_port = src->sin_port; GNUNET_TUN_initialize_ipv4_header (&ip4, IPPROTO_UDP, reply_len - off - sizeof (struct GNUNET_TUN_IPv4Header), &dst->sin_addr, &src->sin_addr); memcpy (&buf[off], &ip4, sizeof (ip4)); off += sizeof (ip4); } break; case AF_INET6: { struct sockaddr_in6 *src = (struct sockaddr_in6 *) &rr->src_addr; struct sockaddr_in6 *dst = (struct sockaddr_in6 *) &rr->dst_addr; source_port = dst->sin6_port; destination_port = src->sin6_port; GNUNET_TUN_initialize_ipv6_header (&ip6, IPPROTO_UDP, reply_len - sizeof (struct GNUNET_TUN_IPv6Header), &dst->sin6_addr, &src->sin6_addr); memcpy (&buf[off], &ip6, sizeof (ip6)); off += sizeof (ip6); } break; default: GNUNET_assert (0); } /* now UDP header */ { struct GNUNET_TUN_UdpHeader udp; udp.source_port = source_port; udp.destination_port = destination_port; udp.len = htons (reply_len - off); if (AF_INET == rr->src_addr.ss_family) GNUNET_TUN_calculate_udp4_checksum (&ip4, &udp, rr->payload, rr->payload_length); else GNUNET_TUN_calculate_udp6_checksum (&ip6, &udp, rr->payload, rr->payload_length); memcpy (&buf[off], &udp, sizeof (udp)); off += sizeof (udp); } /* now DNS payload */ { memcpy (&buf[off], rr->payload, rr->payload_length); off += rr->payload_length; } /* final checks & sending */ GNUNET_assert (off == reply_len); (void) GNUNET_HELPER_send (hijacker, hdr, GNUNET_YES, NULL, NULL); GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests answered via TUN interface"), 1, GNUNET_NO); } /* clean up, we're done */ cleanup_rr (rr); } /** * Show the payload of the given request record to the client * (and wait for a response). * * @param rr request to send to client * @param client client to send the response to */ static void send_request_to_client (struct RequestRecord *rr, struct GNUNET_SERVER_Client *client) { char buf[sizeof (struct GNUNET_DNS_Request) + rr->payload_length] GNUNET_ALIGN; struct GNUNET_DNS_Request *req; if (sizeof (buf) >= GNUNET_SERVER_MAX_MESSAGE_SIZE) { GNUNET_break (0); cleanup_rr (rr); return; } LOG (GNUNET_ERROR_TYPE_DEBUG, "Sending information about request %llu to local client\n", (unsigned long long) rr->request_id); req = (struct GNUNET_DNS_Request*) buf; req->header.type = htons (GNUNET_MESSAGE_TYPE_DNS_CLIENT_REQUEST); req->header.size = htons (sizeof (buf)); req->reserved = htonl (0); req->request_id = rr->request_id; memcpy (&req[1], rr->payload, rr->payload_length); GNUNET_SERVER_notification_context_unicast (nc, client, &req->header, GNUNET_NO); } /** * Callback called from DNSSTUB resolver when a resolution * succeeded. * * @param cls NULL * @param rs the socket that received the response * @param dns the response itself * @param r number of bytes in dns */ static void process_dns_result (void *cls, struct GNUNET_DNSSTUB_RequestSocket *rs, const struct GNUNET_TUN_DnsHeader *dns, size_t r); /** * A client has completed its processing for this * request. Move on. * * @param rr request to process further */ static void next_phase (struct RequestRecord *rr) { struct ClientRecord *cr; int nz; unsigned int j; socklen_t salen; if (rr->phase == RP_DROP) { cleanup_rr (rr); return; } nz = -1; for (j=0;jclient_wait_list_length;j++) { if (NULL != rr->client_wait_list[j]) { nz = (int) j; break; } } if (-1 != nz) { send_request_to_client (rr, rr->client_wait_list[nz]->client); return; } /* done with current phase, advance! */ LOG (GNUNET_ERROR_TYPE_DEBUG, "Request %llu now in phase %d\n", rr->request_id, rr->phase); switch (rr->phase) { case RP_INIT: rr->phase = RP_REQUEST_MONITOR; for (cr = clients_head; NULL != cr; cr = cr->next) { if (0 != (cr->flags & GNUNET_DNS_FLAG_REQUEST_MONITOR)) GNUNET_array_append (rr->client_wait_list, rr->client_wait_list_length, cr); } next_phase (rr); return; case RP_REQUEST_MONITOR: rr->phase = RP_QUERY; for (cr = clients_head; NULL != cr; cr = cr->next) { if (0 != (cr->flags & GNUNET_DNS_FLAG_PRE_RESOLUTION)) GNUNET_array_append (rr->client_wait_list, rr->client_wait_list_length, cr); } next_phase (rr); return; case RP_QUERY: switch (rr->dst_addr.ss_family) { case AF_INET: salen = sizeof (struct sockaddr_in); break; case AF_INET6: salen = sizeof (struct sockaddr_in6); break; default: GNUNET_assert (0); } rr->phase = RP_INTERNET_DNS; rr->rs = GNUNET_DNSSTUB_resolve (dnsstub, (struct sockaddr*) &rr->dst_addr, salen, rr->payload, rr->payload_length, &process_dns_result, NULL); if (NULL == rr->rs) { GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS exit failed (failed to open socket)"), 1, GNUNET_NO); cleanup_rr (rr); return; } return; case RP_INTERNET_DNS: rr->phase = RP_MODIFY; for (cr = clients_head; NULL != cr; cr = cr->next) { if (0 != (cr->flags & GNUNET_DNS_FLAG_POST_RESOLUTION)) GNUNET_array_append (rr->client_wait_list, rr->client_wait_list_length, cr); } next_phase (rr); return; case RP_MODIFY: rr->phase = RP_RESPONSE_MONITOR; for (cr = clients_head; NULL != cr; cr = cr->next) { if (0 != (cr->flags & GNUNET_DNS_FLAG_RESPONSE_MONITOR)) GNUNET_array_append (rr->client_wait_list, rr->client_wait_list_length, cr); } next_phase (rr); return; case RP_RESPONSE_MONITOR: request_done (rr); break; case RP_DROP: cleanup_rr (rr); break; default: GNUNET_break (0); cleanup_rr (rr); break; } } /** * A client disconnected, clean up after it. * * @param cls unused * @param client handle of client that disconnected */ static void client_disconnect (void *cls, struct GNUNET_SERVER_Client *client) { struct ClientRecord *cr; struct RequestRecord *rr; unsigned int i; unsigned int j; for (cr = clients_head; NULL != cr; cr = cr->next) { if (cr->client == client) { GNUNET_SERVER_client_drop (client); GNUNET_CONTAINER_DLL_remove (clients_head, clients_tail, cr); for (i=0;iclient_wait_list_length) continue; /* not in use */ for (j=0;jclient_wait_list_length;j++) { if (rr->client_wait_list[j] == cr) { rr->client_wait_list[j] = NULL; next_phase (rr); } } } GNUNET_free (cr); return; } } } /** * Callback called from DNSSTUB resolver when a resolution * succeeded. * * @param cls NULL * @param rs the socket that received the response * @param dns the response itself * @param r number of bytes in dns */ static void process_dns_result (void *cls, struct GNUNET_DNSSTUB_RequestSocket *rs, const struct GNUNET_TUN_DnsHeader *dns, size_t r) { struct RequestRecord *rr; GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Processing DNS result from stub resolver\n"); GNUNET_assert (NULL == cls); rr = &requests[dns->id]; if ( (rr->phase != RP_INTERNET_DNS) || (rr->rs != rs) ) { /* unexpected / bogus reply */ GNUNET_STATISTICS_update (stats, gettext_noop ("# External DNS response discarded (no matching request)"), 1, GNUNET_NO); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Received DNS reply that does not match any pending request. Dropping.\n"); return; } LOG (GNUNET_ERROR_TYPE_DEBUG, "Got a response from the stub resolver for DNS request %llu intercepted locally!\n", (unsigned long long) rr->request_id); GNUNET_free_non_null (rr->payload); rr->payload = GNUNET_malloc (r); memcpy (rr->payload, dns, r); rr->payload_length = r; next_phase (rr); } /** * We got a new client. Make sure all new DNS requests pass by its desk. * * @param cls unused * @param client the new client * @param message the init message (unused) */ static void handle_client_init (void *cls GNUNET_UNUSED, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message) { struct ClientRecord *cr; const struct GNUNET_DNS_Register *reg = (const struct GNUNET_DNS_Register*) message; cr = GNUNET_new (struct ClientRecord); cr->client = client; cr->flags = (enum GNUNET_DNS_Flags) ntohl (reg->flags); GNUNET_SERVER_client_keep (client); GNUNET_CONTAINER_DLL_insert (clients_head, clients_tail, cr); GNUNET_SERVER_notification_context_add (nc, client); GNUNET_SERVER_receive_done (client, GNUNET_OK); } /** * We got a response from a client. * * @param cls unused * @param client the client * @param message the response */ static void handle_client_response (void *cls GNUNET_UNUSED, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message) { const struct GNUNET_DNS_Response *resp; struct RequestRecord *rr; unsigned int i; uint16_t msize; uint16_t off; msize = ntohs (message->size); if (msize < sizeof (struct GNUNET_DNS_Response)) { GNUNET_break (0); GNUNET_SERVER_receive_done (client, GNUNET_SYSERR); return; } resp = (const struct GNUNET_DNS_Response*) message; off = (uint16_t) resp->request_id; rr = &requests[off]; LOG (GNUNET_ERROR_TYPE_DEBUG, "Received DNS response with ID %llu from local client!\n", (unsigned long long) resp->request_id); if (rr->request_id != resp->request_id) { GNUNET_STATISTICS_update (stats, gettext_noop ("# Client response discarded (no matching request)"), 1, GNUNET_NO); GNUNET_SERVER_receive_done (client, GNUNET_OK); return; } for (i=0;iclient_wait_list_length;i++) { if (NULL == rr->client_wait_list[i]) continue; if (rr->client_wait_list[i]->client != client) continue; rr->client_wait_list[i] = NULL; switch (ntohl (resp->drop_flag)) { case 0: /* drop */ rr->phase = RP_DROP; break; case 1: /* no change */ break; case 2: /* update */ msize -= sizeof (struct GNUNET_DNS_Response); if ( (sizeof (struct GNUNET_TUN_DnsHeader) > msize) || (RP_REQUEST_MONITOR == rr->phase) || (RP_RESPONSE_MONITOR == rr->phase) ) { GNUNET_break (0); GNUNET_SERVER_receive_done (client, GNUNET_SYSERR); next_phase (rr); return; } GNUNET_free_non_null (rr->payload); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Changing DNS reply according to client specifications\n"); rr->payload = GNUNET_malloc (msize); rr->payload_length = msize; memcpy (rr->payload, &resp[1], msize); if (rr->phase == RP_QUERY) { /* clear wait list, we're moving to MODIFY phase next */ GNUNET_array_grow (rr->client_wait_list, rr->client_wait_list_length, 0); } /* if query changed to answer, move past DNS resolution phase... */ if ( (RP_QUERY == rr->phase) && (rr->payload_length > sizeof (struct GNUNET_TUN_DnsHeader)) && ((struct GNUNET_TUN_DnsFlags*)&(((struct GNUNET_TUN_DnsHeader*) rr->payload)->flags))->query_or_response == 1) { rr->phase = RP_INTERNET_DNS; GNUNET_array_grow (rr->client_wait_list, rr->client_wait_list_length, 0); } break; } next_phase (rr); GNUNET_SERVER_receive_done (client, GNUNET_OK); return; } /* odd, client was not on our list for the request, that ought to be an error */ GNUNET_break (0); GNUNET_SERVER_receive_done (client, GNUNET_SYSERR); } /** * Functions with this signature are called whenever a complete * message is received by the tokenizer from the DNS hijack process. * * @param cls closure * @param client identification of the client * @param message the actual message, a DNS request we should handle */ static int process_helper_messages (void *cls GNUNET_UNUSED, void *client, const struct GNUNET_MessageHeader *message) { uint16_t msize; const struct GNUNET_TUN_Layer2PacketHeader *tun; const struct GNUNET_TUN_IPv4Header *ip4; const struct GNUNET_TUN_IPv6Header *ip6; const struct GNUNET_TUN_UdpHeader *udp; const struct GNUNET_TUN_DnsHeader *dns; struct RequestRecord *rr; struct sockaddr_in *srca4; struct sockaddr_in6 *srca6; struct sockaddr_in *dsta4; struct sockaddr_in6 *dsta6; LOG (GNUNET_ERROR_TYPE_DEBUG, "Intercepted message via DNS hijacker\n"); msize = ntohs (message->size); if (msize < sizeof (struct GNUNET_MessageHeader) + sizeof (struct GNUNET_TUN_Layer2PacketHeader) + sizeof (struct GNUNET_TUN_IPv4Header)) { /* non-IP packet received on TUN!? */ GNUNET_break (0); return GNUNET_OK; } msize -= sizeof (struct GNUNET_MessageHeader); tun = (const struct GNUNET_TUN_Layer2PacketHeader *) &message[1]; msize -= sizeof (struct GNUNET_TUN_Layer2PacketHeader); switch (ntohs (tun->proto)) { case ETH_P_IPV4: ip4 = (const struct GNUNET_TUN_IPv4Header *) &tun[1]; ip6 = NULL; /* make compiler happy */ if ( (msize < sizeof (struct GNUNET_TUN_IPv4Header)) || (ip4->version != 4) || (ip4->header_length != sizeof (struct GNUNET_TUN_IPv4Header) / 4) || (ntohs(ip4->total_length) != msize) || (ip4->protocol != IPPROTO_UDP) ) { /* non-IP/UDP packet received on TUN (or with options) */ GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Received malformed IPv4-UDP packet on TUN interface.\n")); return GNUNET_OK; } udp = (const struct GNUNET_TUN_UdpHeader*) &ip4[1]; msize -= sizeof (struct GNUNET_TUN_IPv4Header); break; case ETH_P_IPV6: ip4 = NULL; /* make compiler happy */ ip6 = (const struct GNUNET_TUN_IPv6Header *) &tun[1]; if ( (msize < sizeof (struct GNUNET_TUN_IPv6Header)) || (ip6->version != 6) || (ntohs (ip6->payload_length) != msize) || (ip6->next_header != IPPROTO_UDP) ) { /* non-IP/UDP packet received on TUN (or with extensions) */ GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Received malformed IPv6-UDP packet on TUN interface.\n")); return GNUNET_OK; } udp = (const struct GNUNET_TUN_UdpHeader*) &ip6[1]; msize -= sizeof (struct GNUNET_TUN_IPv6Header); break; default: /* non-IP packet received on TUN!? */ GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Got non-IP packet with %u bytes and protocol %u from TUN\n"), (unsigned int) msize, ntohs (tun->proto)); return GNUNET_OK; } if ( (msize <= sizeof (struct GNUNET_TUN_UdpHeader) + sizeof (struct GNUNET_TUN_DnsHeader)) || (DNS_PORT != ntohs (udp->destination_port)) ) { /* non-DNS packet received on TUN, ignore */ GNUNET_STATISTICS_update (stats, gettext_noop ("# Non-DNS UDP packet received via TUN interface"), 1, GNUNET_NO); return GNUNET_OK; } msize -= sizeof (struct GNUNET_TUN_UdpHeader); dns = (const struct GNUNET_TUN_DnsHeader*) &udp[1]; rr = &requests[dns->id]; /* clean up from previous request */ GNUNET_free_non_null (rr->payload); rr->payload = NULL; GNUNET_array_grow (rr->client_wait_list, rr->client_wait_list_length, 0); /* setup new request */ rr->phase = RP_INIT; switch (ntohs (tun->proto)) { case ETH_P_IPV4: { srca4 = (struct sockaddr_in*) &rr->src_addr; dsta4 = (struct sockaddr_in*) &rr->dst_addr; memset (srca4, 0, sizeof (struct sockaddr_in)); memset (dsta4, 0, sizeof (struct sockaddr_in)); srca4->sin_family = AF_INET; dsta4->sin_family = AF_INET; srca4->sin_addr = ip4->source_address; dsta4->sin_addr = ip4->destination_address; srca4->sin_port = udp->source_port; dsta4->sin_port = udp->destination_port; #if HAVE_SOCKADDR_IN_SIN_LEN srca4->sin_len = sizeof (struct sockaddr_in); dsta4->sin_len = sizeof (struct sockaddr_in); #endif } break; case ETH_P_IPV6: { srca6 = (struct sockaddr_in6*) &rr->src_addr; dsta6 = (struct sockaddr_in6*) &rr->dst_addr; memset (srca6, 0, sizeof (struct sockaddr_in6)); memset (dsta6, 0, sizeof (struct sockaddr_in6)); srca6->sin6_family = AF_INET6; dsta6->sin6_family = AF_INET6; srca6->sin6_addr = ip6->source_address; dsta6->sin6_addr = ip6->destination_address; srca6->sin6_port = udp->source_port; dsta6->sin6_port = udp->destination_port; #if HAVE_SOCKADDR_IN_SIN_LEN srca6->sin6_len = sizeof (struct sockaddr_in6); dsta6->sin6_len = sizeof (struct sockaddr_in6); #endif } break; default: GNUNET_assert (0); } rr->payload = GNUNET_malloc (msize); rr->payload_length = msize; memcpy (rr->payload, dns, msize); rr->request_id = dns->id | (request_id_gen << 16); request_id_gen++; LOG (GNUNET_ERROR_TYPE_DEBUG, "Creating new DNS request %llu\n", (unsigned long long) rr->request_id); GNUNET_STATISTICS_update (stats, gettext_noop ("# DNS requests received via TUN interface"), 1, GNUNET_NO); /* start request processing state machine */ next_phase (rr); return GNUNET_OK; } /** * @param cls closure * @param server the initialized server * @param cfg_ configuration to use */ static void run (void *cls, struct GNUNET_SERVER_Handle *server, const struct GNUNET_CONFIGURATION_Handle *cfg_) { static const struct GNUNET_SERVER_MessageHandler handlers[] = { /* callback, cls, type, size */ {&handle_client_init, NULL, GNUNET_MESSAGE_TYPE_DNS_CLIENT_INIT, sizeof (struct GNUNET_DNS_Register)}, {&handle_client_response, NULL, GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE, 0}, {NULL, NULL, 0, 0} }; char *ifc_name; char *ipv4addr; char *ipv4mask; char *ipv6addr; char *ipv6prefix; struct in_addr dns_exit4; struct in6_addr dns_exit6; char *dns_exit; char *binary; cfg = cfg_; binary = GNUNET_OS_get_libexec_binary_path ("gnunet-helper-dns"); if (GNUNET_YES != GNUNET_OS_check_helper_binary (binary, GNUNET_YES, NULL)) // TODO: once we have a windows-testcase, add test parameters here { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _("`%s' must be installed SUID, refusing to run\n"), binary); global_ret = 1; GNUNET_free (binary); return; } GNUNET_free (binary); stats = GNUNET_STATISTICS_create ("dns", cfg); nc = GNUNET_SERVER_notification_context_create (server, 1); GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL, &cleanup_task, cls); dns_exit = NULL; if ( ( (GNUNET_OK != GNUNET_CONFIGURATION_get_value_string (cfg, "dns", "DNS_EXIT", &dns_exit)) || ( (1 != inet_pton (AF_INET, dns_exit, &dns_exit4)) && (1 != inet_pton (AF_INET6, dns_exit, &dns_exit6)) ) ) ) { GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR, "dns", "DNS_EXIT", _("need a valid IPv4 or IPv6 address\n")); GNUNET_free_non_null (dns_exit); dns_exit = NULL; } dnsstub = GNUNET_DNSSTUB_start (dns_exit); GNUNET_free_non_null (dns_exit); helper_argv[0] = GNUNET_strdup ("gnunet-dns"); if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string (cfg, "dns", "IFNAME", &ifc_name)) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No entry 'IFNAME' in configuration!\n"); GNUNET_SCHEDULER_shutdown (); return; } helper_argv[1] = ifc_name; if ( (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string (cfg, "dns", "IPV6ADDR", &ipv6addr)) ) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6ADDR' in configuration!\n"); GNUNET_SCHEDULER_shutdown (); return; } helper_argv[2] = ipv6addr; if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string (cfg, "dns", "IPV6PREFIX", &ipv6prefix)) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6PREFIX' in configuration!\n"); GNUNET_SCHEDULER_shutdown (); return; } helper_argv[3] = ipv6prefix; if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string (cfg, "dns", "IPV4ADDR", &ipv4addr)) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4ADDR' in configuration!\n"); GNUNET_SCHEDULER_shutdown (); return; } helper_argv[4] = ipv4addr; if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string (cfg, "dns", "IPV4MASK", &ipv4mask)) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4MASK' in configuration!\n"); GNUNET_SCHEDULER_shutdown (); return; } helper_argv[5] = ipv4mask; helper_argv[6] = NULL; hijacker = GNUNET_HELPER_start (GNUNET_NO, "gnunet-helper-dns", helper_argv, &process_helper_messages, NULL, NULL); GNUNET_SERVER_add_handlers (server, handlers); GNUNET_SERVER_disconnect_notify (server, &client_disconnect, NULL); } /** * The main function for the dns service. * * @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) { /* make use of SGID capabilities on POSIX */ /* FIXME: this might need a port on systems without 'getresgid' */ #if HAVE_GETRESGID gid_t rgid; gid_t egid; gid_t sgid; if (-1 == getresgid (&rgid, &egid, &sgid)) { fprintf (stderr, "getresgid failed: %s\n", strerror (errno)); } else if (sgid != rgid) { if (-1 == setregid (sgid, sgid)) fprintf (stderr, "setregid failed: %s\n", strerror (errno)); } #endif return (GNUNET_OK == GNUNET_SERVICE_run (argc, argv, "dns", GNUNET_SERVICE_OPTION_NONE, &run, NULL)) ? global_ret : 1; } /* end of gnunet-service-dns.c */