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Diffstat (limited to 'src/dns/gnunet-service-dns.c')
| -rw-r--r-- | src/dns/gnunet-service-dns.c | 1667 |
1 files changed, 1667 insertions, 0 deletions
diff --git a/src/dns/gnunet-service-dns.c b/src/dns/gnunet-service-dns.c new file mode 100644 index 0000000..1f48b10 --- /dev/null +++ b/src/dns/gnunet-service-dns.c @@ -0,0 +1,1667 @@ +/* + This file is part of GNUnet. + (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_mesh_service.h" +#include "gnunet_statistics_service.h" +#include "gnunet_tun_lib.h" + + +/** + * Timeout for an external (Internet-DNS) DNS resolution + */ +#define REQUEST_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5) + +/** + * How many DNS sockets do we open at most at the same time? + * (technical socket maximum is this number x2 for IPv4+IPv6) + */ +#define DNS_SOCKET_MAX 128 + +/** + * 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; + +}; + + +/** + * UDP socket we are using for sending DNS requests to the Internet. + */ +struct RequestSocket +{ + + /** + * UDP socket we use for this request for IPv4 + */ + struct GNUNET_NETWORK_Handle *dnsout4; + + /** + * UDP socket we use for this request for IPv6 + */ + struct GNUNET_NETWORK_Handle *dnsout6; + + /** + * Task for reading from dnsout4 and dnsout6. + */ + GNUNET_SCHEDULER_TaskIdentifier read_task; + + /** + * When should this socket be closed? + */ + struct GNUNET_TIME_Absolute timeout; +}; + + +/** + * 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). Must NOT be freed as part of this request record (as it + * might be shared with other requests). + */ + struct GNUNET_NETWORK_Handle *dnsout; + + /** + * 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; + + /** + * When should this request time out? + */ + struct GNUNET_TIME_Absolute timeout; + + /** + * 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; + +}; + + +/** + * State we keep for each DNS tunnel that terminates at this node. + */ +struct TunnelState +{ + + /** + * Associated MESH tunnel. + */ + struct GNUNET_MESH_Tunnel *tunnel; + + /** + * Active request for sending a reply. + */ + struct GNUNET_MESH_TransmitHandle *th; + + /** + * DNS reply ready for transmission. + */ + char *reply; + + /** + * Socket we are using to transmit this request (must match if we receive + * a response). Must NOT be freed as part of this request record (as it + * might be shared with other requests). + */ + struct GNUNET_NETWORK_Handle *dnsout; + + /** + * Address we sent the DNS request to. + */ + struct sockaddr_storage addr; + + /** + * When should this request time out? + */ + struct GNUNET_TIME_Absolute timeout; + + /** + * Number of bytes in 'addr'. + */ + socklen_t addrlen; + + /** + * Number of bytes in 'reply'. + */ + size_t reply_length; + + /** + * Original DNS request ID as used by the client. + */ + uint16_t original_id; + + /** + * DNS request ID that we used for forwarding. + */ + uint16_t my_id; +}; + + +/** + * 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]; + +/** + * Array of all open requests from tunnels. + */ +static struct TunnelState *tunnels[UINT16_MAX + 1]; + +/** + * Array of all open sockets for DNS requests. + */ +static struct RequestSocket sockets[DNS_SOCKET_MAX]; + +/** + * Generator for unique request IDs. + */ +static uint64_t request_id_gen; + +/** + * IP address to use for the DNS server if we are a DNS exit service + * (for VPN via mesh); otherwise NULL. + */ +static char *dns_exit; + +/** + * Handle to the MESH service (for receiving DNS queries), or NULL + * if we are not a DNS exit. + */ +static struct GNUNET_MESH_Handle *mesh; + + +/** + * We're done with a RequestSocket, close it for now. + * + * @param rs request socket to clean up + */ +static void +cleanup_rs (struct RequestSocket *rs) +{ + if (NULL != rs->dnsout4) + { + GNUNET_NETWORK_socket_close (rs->dnsout4); + rs->dnsout4 = NULL; + } + if (NULL != rs->dnsout6) + { + GNUNET_NETWORK_socket_close (rs->dnsout6); + rs->dnsout6 = NULL; + } + if (GNUNET_SCHEDULER_NO_TASK != rs->read_task) + { + GNUNET_SCHEDULER_cancel (rs->read_task); + rs->read_task = GNUNET_SCHEDULER_NO_TASK; + } +} + + +/** + * 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); + 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 != dns_exit) + { + GNUNET_free (dns_exit); + dns_exit = NULL; + } + if (NULL != mesh) + { + GNUNET_MESH_disconnect(mesh); + mesh = NULL; + } +} + + +/** + * Open source port for sending DNS requests + * + * @param af AF_INET or AF_INET6 + * @return GNUNET_OK on success + */ +static struct GNUNET_NETWORK_Handle * +open_socket (int af) +{ + struct sockaddr_in a4; + struct sockaddr_in6 a6; + struct sockaddr *sa; + socklen_t alen; + struct GNUNET_NETWORK_Handle *ret; + + ret = GNUNET_NETWORK_socket_create (af, SOCK_DGRAM, 0); + if (NULL == ret) + return NULL; + switch (af) + { + case AF_INET: + memset (&a4, 0, alen = sizeof (struct sockaddr_in)); + sa = (struct sockaddr *) &a4; + break; + case AF_INET6: + memset (&a6, 0, alen = sizeof (struct sockaddr_in6)); + sa = (struct sockaddr *) &a6; + break; + default: + GNUNET_break (0); + GNUNET_NETWORK_socket_close (ret); + return NULL; + } + sa->sa_family = af; + if (GNUNET_OK != GNUNET_NETWORK_socket_bind (ret, + sa, + alen)) + { + GNUNET_log (GNUNET_ERROR_TYPE_ERROR, + _("Could not bind to any port: %s\n"), + STRERROR (errno)); + GNUNET_NETWORK_socket_close (ret); + return NULL; + } + return ret; +} + + +/** + * 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 */ + cleanup_rr (rr); + return; + } + + /* 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]; + 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); + 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]; + struct GNUNET_DNS_Request *req; + + if (sizeof (buf) >= GNUNET_SERVER_MAX_MESSAGE_SIZE) + { + GNUNET_break (0); + cleanup_rr (rr); + return; + } + 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); +} + + +/** + * Read a DNS response from the (unhindered) UDP-Socket + * + * @param cls socket to read from + * @param tc scheduler context (must be shutdown or read ready) + */ +static void +read_response (void *cls, + const struct GNUNET_SCHEDULER_TaskContext *tc); + + +/** + * Get a socket of the specified address family to send out a + * UDP DNS request to the Internet. + * + * @param af desired address family + * @return NULL on error (given AF not "supported") + */ +static struct GNUNET_NETWORK_Handle * +get_request_socket (int af) +{ + struct RequestSocket *rs; + struct GNUNET_NETWORK_FDSet *rset; + static struct GNUNET_NETWORK_Handle *ret; + + rs = &sockets[GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, + DNS_SOCKET_MAX)]; + rs->timeout = GNUNET_TIME_relative_to_absolute (REQUEST_TIMEOUT); + switch (af) + { + case AF_INET: + if (NULL == rs->dnsout4) + rs->dnsout4 = open_socket (AF_INET); + ret = rs->dnsout4; + break; + case AF_INET6: + if (NULL == rs->dnsout6) + rs->dnsout6 = open_socket (AF_INET6); + ret = rs->dnsout6; + break; + default: + return NULL; + } + if (GNUNET_SCHEDULER_NO_TASK != rs->read_task) + { + GNUNET_SCHEDULER_cancel (rs->read_task); + rs->read_task = GNUNET_SCHEDULER_NO_TASK; + } + if ( (NULL == rs->dnsout4) && + (NULL == rs->dnsout6) ) + return NULL; + rset = GNUNET_NETWORK_fdset_create (); + if (NULL != rs->dnsout4) + GNUNET_NETWORK_fdset_set (rset, rs->dnsout4); + if (NULL != rs->dnsout6) + GNUNET_NETWORK_fdset_set (rset, rs->dnsout6); + rs->read_task = GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_DEFAULT, + GNUNET_SCHEDULER_NO_TASK, + REQUEST_TIMEOUT, + rset, + NULL, + &read_response, rs); + GNUNET_NETWORK_fdset_destroy (rset); + return ret; +} + + +/** + * 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;j<rr->client_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! */ + 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->dnsout = get_request_socket (rr->dst_addr.ss_family); + if (NULL == rr->dnsout) + { + GNUNET_STATISTICS_update (stats, + gettext_noop ("# DNS exit failed (failed to open socket)"), + 1, GNUNET_NO); + cleanup_rr (rr); + return; + } + GNUNET_NETWORK_socket_sendto (rr->dnsout, + rr->payload, + rr->payload_length, + (struct sockaddr*) &rr->dst_addr, + salen); + rr->timeout = GNUNET_TIME_relative_to_absolute (REQUEST_TIMEOUT); + 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;i<UINT16_MAX;i++) + { + rr = &requests[i]; + if (0 == rr->client_wait_list_length) + continue; /* not in use */ + for (j=0;j<rr->client_wait_list_length;j++) + { + if (rr->client_wait_list[j] == cr) + { + rr->client_wait_list[j] = NULL; + next_phase (rr); + } + } + } + GNUNET_free (cr); + return; + } + } +} + + +/** + * We got a reply from DNS for a request of a MESH tunnel. Send it + * via the tunnel (after changing the request ID back). + * + * @param cls the 'struct TunnelState' + * @param size number of bytes available in buf + * @param buf where to copy the reply + * @return number of bytes written to buf + */ +static size_t +transmit_reply_to_mesh (void *cls, + size_t size, + void *buf) +{ + struct TunnelState *ts = cls; + size_t off; + size_t ret; + char *cbuf = buf; + struct GNUNET_MessageHeader hdr; + struct GNUNET_TUN_DnsHeader dns; + + ts->th = NULL; + GNUNET_assert (ts->reply != NULL); + if (size == 0) + return 0; + ret = sizeof (struct GNUNET_MessageHeader) + ts->reply_length; + GNUNET_assert (ret <= size); + hdr.size = htons (ret); + hdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_DNS_FROM_INTERNET); + memcpy (&dns, ts->reply, sizeof (dns)); + dns.id = ts->original_id; + off = 0; + memcpy (&cbuf[off], &hdr, sizeof (hdr)); + off += sizeof (hdr); + memcpy (&cbuf[off], &dns, sizeof (dns)); + off += sizeof (dns); + memcpy (&cbuf[off], &ts->reply[sizeof (dns)], ts->reply_length - sizeof (dns)); + off += ts->reply_length - sizeof (dns); + GNUNET_free (ts->reply); + ts->reply = NULL; + ts->reply_length = 0; + GNUNET_assert (ret == off); + return ret; +} + + +/** + * Actually do the reading of a DNS packet from our UDP socket and see + * if we have a valid, matching, pending request. + * + * @param dnsout socket to read from + * @return GNUNET_OK on success, GNUNET_NO on drop, GNUNET_SYSERR on IO-errors (closed socket) + */ +static int +do_dns_read (struct GNUNET_NETWORK_Handle *dnsout) +{ + struct sockaddr_storage addr; + socklen_t addrlen; + struct GNUNET_TUN_DnsHeader *dns; + struct RequestRecord *rr; + struct TunnelState *ts; + ssize_t r; + int len; + +#ifndef MINGW + if (0 != ioctl (GNUNET_NETWORK_get_fd (dnsout), FIONREAD, &len)) + { + /* conservative choice: */ + len = UINT16_MAX; + } +#else + /* port the code above? */ + len = UINT16_MAX; +#endif + + { + unsigned char buf[len]; + + addrlen = sizeof (addr); + memset (&addr, 0, sizeof (addr)); + r = GNUNET_NETWORK_socket_recvfrom (dnsout, + buf, sizeof (buf), + (struct sockaddr*) &addr, &addrlen); + if (-1 == r) + { + GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "recvfrom"); + GNUNET_NETWORK_socket_close (dnsout); + return GNUNET_SYSERR; + } + if (sizeof (struct GNUNET_TUN_DnsHeader) > r) + { + GNUNET_log (GNUNET_ERROR_TYPE_ERROR, + _("Received DNS response that is too small (%u bytes)"), + r); + return GNUNET_NO; + } + dns = (struct GNUNET_TUN_DnsHeader *) buf; + /* Handle case that this is a reply to a request from a MESH DNS tunnel */ + ts = tunnels[dns->id]; + if ( (NULL == ts) || + (ts->dnsout != dnsout) || + (addrlen != ts->addrlen) || + (0 != memcmp (&ts->addr, + &addr, + addrlen)) || + (0 == GNUNET_TIME_absolute_get_remaining (ts->timeout).rel_value) ) + ts = NULL; /* DNS responder address missmatch */ + if (NULL != ts) + { + tunnels[dns->id] = NULL; + GNUNET_free_non_null (ts->reply); + ts->reply = GNUNET_malloc (r); + ts->reply_length = r; + memcpy (ts->reply, dns, r); + if (ts->th != NULL) + GNUNET_MESH_notify_transmit_ready_cancel (ts->th); + ts->th = GNUNET_MESH_notify_transmit_ready (ts->tunnel, + GNUNET_NO, 0, + GNUNET_TIME_UNIT_FOREVER_REL, + NULL, + sizeof (struct GNUNET_MessageHeader) + r, + &transmit_reply_to_mesh, + ts); + } + /* Handle case that this is a reply to a local request (intercepted from TUN interface) */ + rr = &requests[dns->id]; + if ( (rr->phase != RP_INTERNET_DNS) || + (rr->dnsout != dnsout) || + (0 != memcmp (&rr->dst_addr, + &addr, + addrlen)) || + (0 == GNUNET_TIME_absolute_get_remaining (rr->timeout).rel_value) ) + { + if (NULL == ts) + { + /* unexpected / bogus reply */ + GNUNET_STATISTICS_update (stats, + gettext_noop ("# External DNS response discarded (no matching request)"), + 1, GNUNET_NO); + } + return GNUNET_NO; + } + GNUNET_free_non_null (rr->payload); + rr->payload = GNUNET_malloc (r); + memcpy (rr->payload, buf, r); + rr->payload_length = r; + next_phase (rr); + } + return GNUNET_OK; +} + + +/** + * Read a DNS response from the (unhindered) UDP-Socket + * + * @param cls socket to read from + * @param tc scheduler context (must be shutdown or read ready) + */ +static void +read_response (void *cls, + const struct GNUNET_SCHEDULER_TaskContext *tc) +{ + struct RequestSocket *rs = cls; + struct GNUNET_NETWORK_FDSet *rset; + + rs->read_task = GNUNET_SCHEDULER_NO_TASK; + if (0 == (tc->reason & GNUNET_SCHEDULER_REASON_READ_READY)) + { + /* timeout or shutdown */ + cleanup_rs (rs); + return; + } + /* read and process ready sockets */ + if ((NULL != rs->dnsout4) && + (GNUNET_NETWORK_fdset_isset (tc->read_ready, rs->dnsout4)) && + (GNUNET_SYSERR == do_dns_read (rs->dnsout4))) + rs->dnsout4 = NULL; + if ((NULL != rs->dnsout6) && + (GNUNET_NETWORK_fdset_isset (tc->read_ready, rs->dnsout6)) && + (GNUNET_SYSERR == do_dns_read (rs->dnsout6))) + rs->dnsout6 = NULL; + + /* re-schedule read task */ + rset = GNUNET_NETWORK_fdset_create (); + if (NULL != rs->dnsout4) + GNUNET_NETWORK_fdset_set (rset, rs->dnsout4); + if (NULL != rs->dnsout6) + GNUNET_NETWORK_fdset_set (rset, rs->dnsout6); + rs->read_task = GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_DEFAULT, + GNUNET_SCHEDULER_NO_TASK, + GNUNET_TIME_absolute_get_remaining (rs->timeout), + rset, + NULL, + &read_response, rs); + GNUNET_NETWORK_fdset_destroy (rset); +} + + +/** + * 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_malloc (sizeof (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]; + 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;i<rr->client_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); +#if DEBUG_DNS + GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, + _("Changing DNS reply according to client specifications\n")); +#endif + 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_DNSPARSER_Flags*)&(((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 void +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; + + 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; + } + 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]; + 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; + } + udp = (const struct GNUNET_TUN_UdpHeader*) &ip4[1]; + msize -= sizeof (struct GNUNET_TUN_IPv4Header); + break; + case ETH_P_IPV6: + 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; + } + 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; + } + if (msize <= sizeof (struct GNUNET_TUN_UdpHeader) + sizeof (struct GNUNET_TUN_DnsHeader)) + { + /* 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; + } + 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++; + + GNUNET_STATISTICS_update (stats, + gettext_noop ("# DNS requests received via TUN interface"), + 1, GNUNET_NO); + /* start request processing state machine */ + next_phase (rr); +} + + +/** + * 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_request (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 TunnelState *ts = *tunnel_ctx; + const struct GNUNET_TUN_DnsHeader *dns; + size_t mlen = ntohs (message->size); + size_t dlen = mlen - sizeof (struct GNUNET_MessageHeader); + char buf[dlen]; + struct GNUNET_TUN_DnsHeader *dout; + struct sockaddr_in v4; + struct sockaddr_in6 v6; + struct sockaddr *so; + socklen_t salen; + + if (dlen < sizeof (struct GNUNET_TUN_DnsHeader)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + dns = (const struct GNUNET_TUN_DnsHeader *) &message[1]; + ts->original_id = dns->id; + if (tunnels[ts->my_id] == ts) + tunnels[ts->my_id] = NULL; + ts->my_id = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, + UINT16_MAX + 1); + tunnels[ts->my_id] = ts; + memcpy (buf, dns, dlen); + dout = (struct GNUNET_TUN_DnsHeader*) buf; + dout->id = ts->my_id; + memset (&v4, 0, sizeof (v4)); + memset (&v6, 0, sizeof (v6)); + if (1 == inet_pton (AF_INET, dns_exit, &v4.sin_addr)) + { + salen = sizeof (v4); + v4.sin_family = AF_INET; + v4.sin_port = htons (53); +#if HAVE_SOCKADDR_IN_SIN_LEN + v4.sin_len = (u_char) salen; +#endif + so = (struct sockaddr *) &v4; + ts->dnsout = get_request_socket (AF_INET); + } + else if (1 == inet_pton (AF_INET6, dns_exit, &v6.sin6_addr)) + { + salen = sizeof (v6); + v6.sin6_family = AF_INET6; + v6.sin6_port = htons (53); +#if HAVE_SOCKADDR_IN_SIN_LEN + v6.sin6_len = (u_char) salen; +#endif + so = (struct sockaddr *) &v6; + ts->dnsout = get_request_socket (AF_INET6); + } + else + { + GNUNET_break (0); + return GNUNET_SYSERR; + } + if (NULL == ts->dnsout) + { + GNUNET_log (GNUNET_ERROR_TYPE_ERROR, + _("Configured DNS exit `%s' is not working / valid.\n"), + dns_exit); + return GNUNET_SYSERR; + } + memcpy (&ts->addr, + so, + salen); + ts->addrlen = salen; + GNUNET_NETWORK_socket_sendto (ts->dnsout, + buf, dlen, so, salen); + ts->timeout = GNUNET_TIME_relative_to_absolute (REQUEST_TIMEOUT); + return GNUNET_OK; +} + + +/** + * Callback from GNUNET_MESH for new tunnels. + * + * @param cls closure + * @param tunnel new handle to the tunnel + * @param initiator peer that started the tunnel + * @param ats performance information for the tunnel + * @return initial tunnel context for the tunnel + */ +static void * +accept_dns_tunnel (void *cls GNUNET_UNUSED, struct GNUNET_MESH_Tunnel *tunnel, + const struct GNUNET_PeerIdentity *initiator GNUNET_UNUSED, + const struct GNUNET_ATS_Information *ats GNUNET_UNUSED) +{ + struct TunnelState *ts = GNUNET_malloc (sizeof (struct TunnelState)); + + GNUNET_STATISTICS_update (stats, + gettext_noop ("# Inbound MESH tunnels created"), + 1, GNUNET_NO); + GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, + "Received inbound tunnel from `%s'\n", + GNUNET_i2s (initiator)); + ts->tunnel = tunnel; + return ts; +} + + +/** + * Function called by mesh whenever an inbound tunnel is destroyed. + * Should clean up any associated state. + * + * @param cls closure (set from GNUNET_MESH_connect) + * @param tunnel connection to the other end (henceforth invalid) + * @param tunnel_ctx place where local state associated + * with the tunnel is stored + */ +static void +destroy_dns_tunnel (void *cls GNUNET_UNUSED, + const struct GNUNET_MESH_Tunnel *tunnel, + void *tunnel_ctx) +{ + struct TunnelState *ts = tunnel_ctx; + + if (tunnels[ts->my_id] == ts) + tunnels[ts->my_id] = NULL; + if (NULL != ts->th) + GNUNET_MESH_notify_transmit_ready_cancel (ts->th); + GNUNET_free_non_null (ts->reply); + GNUNET_free (ts); +} + + +/** + * @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; + + cfg = cfg_; + 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); + if ( (GNUNET_YES == + GNUNET_CONFIGURATION_get_value_yesno (cfg_, "dns", "PROVIDE_EXIT")) && + ( (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 (GNUNET_ERROR_TYPE_ERROR, + _("Configured to provide DNS exit, but no valid DNS server configured!\n")); + GNUNET_free_non_null (dns_exit); + dns_exit = NULL; + } + + 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; + + if (NULL != dns_exit) + { + static struct GNUNET_MESH_MessageHandler mesh_handlers[] = { + {&receive_dns_request, GNUNET_MESSAGE_TYPE_VPN_DNS_TO_INTERNET, 0}, + {NULL, 0, 0} + }; + static GNUNET_MESH_ApplicationType mesh_types[] = { + GNUNET_APPLICATION_TYPE_INTERNET_RESOLVER, + GNUNET_APPLICATION_TYPE_END + }; + mesh = GNUNET_MESH_connect (cfg, + 1, NULL, + &accept_dns_tunnel, + &destroy_dns_tunnel, + mesh_handlers, + mesh_types); + } + hijacker = GNUNET_HELPER_start ("gnunet-helper-dns", + helper_argv, + &process_helper_messages, + 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) +{ + return (GNUNET_OK == + GNUNET_SERVICE_run (argc, argv, "dns", GNUNET_SERVICE_OPTION_NONE, + &run, NULL)) ? 0 : 1; +} + + +/* end of gnunet-service-dns.c */ |