source: trunk/server/libcli/nbt/nbtsocket.c

/*
   Unix SMB/CIFS implementation.

   low level socket handling for nbt requests

   Copyright (C) Andrew Tridgell 2005

   This program 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 of the License, or
   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "lib/events/events.h"
#include "../lib/util/dlinklist.h"
#include "../libcli/nbt/libnbt.h"
#include "../libcli/nbt/nbt_proto.h"
#include "lib/socket/socket.h"
#include "librpc/gen_ndr/ndr_nbt.h"
#include "param/param.h"

#define NBT_MAX_REPLIES 1000

/*
  destroy a pending request
*/
static int nbt_name_request_destructor(struct nbt_name_request *req)
{
        if (req->state == NBT_REQUEST_SEND) {
                DLIST_REMOVE(req->nbtsock->send_queue, req);
        }
        if (req->state == NBT_REQUEST_WAIT) {
                req->nbtsock->num_pending--;
        }
        if (req->name_trn_id != 0 && !req->is_reply) {
                idr_remove(req->nbtsock->idr, req->name_trn_id);
                req->name_trn_id = 0;
        }
        if (req->te) {
                talloc_free(req->te);
                req->te = NULL;
        }
        if (req->nbtsock->send_queue == NULL) {
                EVENT_FD_NOT_WRITEABLE(req->nbtsock->fde);
        }
        if (req->nbtsock->num_pending == 0 &&
            req->nbtsock->incoming.handler == NULL) {
                EVENT_FD_NOT_READABLE(req->nbtsock->fde);
        }
        return 0;
}


/*
  handle send events on a nbt name socket
*/
static void nbt_name_socket_send(struct nbt_name_socket *nbtsock)
{
        struct nbt_name_request *req = nbtsock->send_queue;
        TALLOC_CTX *tmp_ctx = talloc_new(nbtsock);
        NTSTATUS status;

        while ((req = nbtsock->send_queue)) {
                size_t len;

                len = req->encoded.length;
                status = socket_sendto(nbtsock->sock, &req->encoded, &len,
                                       req->dest);
                if (NT_STATUS_IS_ERR(status)) goto failed;

                if (!NT_STATUS_IS_OK(status)) {
                        talloc_free(tmp_ctx);
                        return;
                }

                DLIST_REMOVE(nbtsock->send_queue, req);
                req->state = NBT_REQUEST_WAIT;
                if (req->is_reply) {
                        talloc_free(req);
                } else {
                        EVENT_FD_READABLE(nbtsock->fde);
                        nbtsock->num_pending++;
                }
        }

        EVENT_FD_NOT_WRITEABLE(nbtsock->fde);
        talloc_free(tmp_ctx);
        return;

failed:
        DLIST_REMOVE(nbtsock->send_queue, req);
        nbt_name_request_destructor(req);
        req->status = status;
        req->state = NBT_REQUEST_ERROR;
        talloc_free(tmp_ctx);
        if (req->async.fn) {
                req->async.fn(req);
        } else if (req->is_reply) {
                talloc_free(req);
        }
        return;
}


/*
  handle a request timeout
*/
static void nbt_name_socket_timeout(struct tevent_context *ev, struct tevent_timer *te,
                                    struct timeval t, void *private_data)
{
        struct nbt_name_request *req = talloc_get_type(private_data,
                                                       struct nbt_name_request);

        if (req->num_retries != 0) {
                req->num_retries--;
                req->te = event_add_timed(req->nbtsock->event_ctx, req,
                                          timeval_add(&t, req->timeout, 0),
                                          nbt_name_socket_timeout, req);
                if (req->state != NBT_REQUEST_SEND) {
                        req->state = NBT_REQUEST_SEND;
                        DLIST_ADD_END(req->nbtsock->send_queue, req,
                                      struct nbt_name_request *);
                }
                EVENT_FD_WRITEABLE(req->nbtsock->fde);
                return;
        }

        nbt_name_request_destructor(req);
        if (req->num_replies == 0) {
                req->state = NBT_REQUEST_TIMEOUT;
                req->status = NT_STATUS_IO_TIMEOUT;
        } else {
                req->state = NBT_REQUEST_DONE;
                req->status = NT_STATUS_OK;
        }
        if (req->async.fn) {
                req->async.fn(req);
        } else if (req->is_reply) {
                talloc_free(req);
        }
}



/**
  handle recv events on a nbt name socket
*/
static void nbt_name_socket_recv(struct nbt_name_socket *nbtsock)
{
        TALLOC_CTX *tmp_ctx = talloc_new(nbtsock);
        NTSTATUS status;
        enum ndr_err_code ndr_err;
        struct socket_address *src;
        DATA_BLOB blob;
        size_t nread, dsize;
        struct nbt_name_packet *packet;
        struct nbt_name_request *req;

        status = socket_pending(nbtsock->sock, &dsize);
        if (!NT_STATUS_IS_OK(status)) {
                talloc_free(tmp_ctx);
                return;
        }

        blob = data_blob_talloc(tmp_ctx, NULL, dsize);
        if (blob.data == NULL) {
                talloc_free(tmp_ctx);
                return;
        }

        status = socket_recvfrom(nbtsock->sock, blob.data, blob.length, &nread,
                                 tmp_ctx, &src);
        if (!NT_STATUS_IS_OK(status)) {
                talloc_free(tmp_ctx);
                return;
        }

        packet = talloc(tmp_ctx, struct nbt_name_packet);
        if (packet == NULL) {
                talloc_free(tmp_ctx);
                return;
        }

        /* parse the request */
        ndr_err = ndr_pull_struct_blob(&blob, packet, packet,
                                       (ndr_pull_flags_fn_t)ndr_pull_nbt_name_packet);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                status = ndr_map_error2ntstatus(ndr_err);
                DEBUG(2,("Failed to parse incoming NBT name packet - %s\n",
                         nt_errstr(status)));
                talloc_free(tmp_ctx);
                return;
        }

        if (DEBUGLVL(10)) {
                DEBUG(10,("Received nbt packet of length %d from %s:%d\n",
                          (int)blob.length, src->addr, src->port));
                NDR_PRINT_DEBUG(nbt_name_packet, packet);
        }

        /* if its not a reply then pass it off to the incoming request
           handler, if any */
        if (!(packet->operation & NBT_FLAG_REPLY)) {
                if (nbtsock->incoming.handler) {
                        nbtsock->incoming.handler(nbtsock, packet, src);
                }
                talloc_free(tmp_ctx);
                return;
        }

        /* find the matching request */
        req = (struct nbt_name_request *)idr_find(nbtsock->idr,
                                                  packet->name_trn_id);
        if (req == NULL) {
                if (nbtsock->unexpected.handler) {
                        nbtsock->unexpected.handler(nbtsock, packet, src);
                } else {
                        DEBUG(10,("Failed to match request for incoming name packet id 0x%04x on %p\n",
                                 packet->name_trn_id, nbtsock));
                }
                talloc_free(tmp_ctx);
                return;
        }

        talloc_steal(req, packet);
        talloc_steal(req, src);
        talloc_free(tmp_ctx);
        nbt_name_socket_handle_response_packet(req, packet, src);
}

void nbt_name_socket_handle_response_packet(struct nbt_name_request *req,
                                            struct nbt_name_packet *packet,
                                            struct socket_address *src)
{
        /* if this is a WACK response, this we need to go back to waiting,
           but perhaps increase the timeout */
        if ((packet->operation & NBT_OPCODE) == NBT_OPCODE_WACK) {
                uint32_t ttl;
                if (req->received_wack || packet->ancount < 1) {
                        nbt_name_request_destructor(req);
                        req->status = NT_STATUS_INVALID_NETWORK_RESPONSE;
                        req->state  = NBT_REQUEST_ERROR;
                        goto done;
                }
                talloc_free(req->te);
                /* we know we won't need any more retries - the server
                   has received our request */
                req->num_retries   = 0;
                req->received_wack = true;
                /*
                 * there is a timeout in the packet,
                 * it is 5 + 4 * num_old_addresses
                 *
                 * although w2k3 screws it up
                 * and uses num_old_addresses = 0
                 *
                 * so we better fallback to the maximum
                 * of num_old_addresses = 25 if we got
                 * a timeout of less than 9s (5 + 4*1)
                 * or more than 105s (5 + 4*25).
                 */
                ttl = packet->answers[0].ttl;
                if ((ttl < (5 + 4*1)) || (ttl > (5 + 4*25))) {
                        ttl = 5 + 4*25;
                }
                req->timeout = ttl;
                req->te = event_add_timed(req->nbtsock->event_ctx, req,
                                          timeval_current_ofs(req->timeout, 0),
                                          nbt_name_socket_timeout, req);
                return;
        }


        req->replies = talloc_realloc(req, req->replies, struct nbt_name_reply, req->num_replies+1);
        if (req->replies == NULL) {
                nbt_name_request_destructor(req);
                req->state  = NBT_REQUEST_ERROR;
                req->status = NT_STATUS_NO_MEMORY;
                goto done;
        }

        talloc_steal(req, src);
        req->replies[req->num_replies].dest   = src;
        talloc_steal(req, packet);
        req->replies[req->num_replies].packet = packet;
        req->num_replies++;

        /* if we don't want multiple replies then we are done */
        if (req->allow_multiple_replies &&
            req->num_replies < NBT_MAX_REPLIES) {
                return;
        }

        nbt_name_request_destructor(req);
        req->state  = NBT_REQUEST_DONE;
        req->status = NT_STATUS_OK;

done:
        if (req->async.fn) {
                req->async.fn(req);
        }
}

/*
  handle fd events on a nbt_name_socket
*/
static void nbt_name_socket_handler(struct tevent_context *ev, struct tevent_fd *fde,
                                    uint16_t flags, void *private_data)
{
        struct nbt_name_socket *nbtsock = talloc_get_type(private_data,
                                                          struct nbt_name_socket);
        if (flags & EVENT_FD_WRITE) {
                nbt_name_socket_send(nbtsock);
        }
        if (flags & EVENT_FD_READ) {
                nbt_name_socket_recv(nbtsock);
        }
}


/*
  initialise a nbt_name_socket. The event_ctx is optional, if provided
  then operations will use that event context
*/
_PUBLIC_ struct nbt_name_socket *nbt_name_socket_init(TALLOC_CTX *mem_ctx,
                                             struct tevent_context *event_ctx)
{
        struct nbt_name_socket *nbtsock;
        NTSTATUS status;

        nbtsock = talloc(mem_ctx, struct nbt_name_socket);
        if (nbtsock == NULL) goto failed;

        nbtsock->event_ctx = event_ctx;
        if (nbtsock->event_ctx == NULL) goto failed;

        status = socket_create("ip", SOCKET_TYPE_DGRAM, &nbtsock->sock, 0);
        if (!NT_STATUS_IS_OK(status)) goto failed;

        socket_set_option(nbtsock->sock, "SO_BROADCAST", "1");

        talloc_steal(nbtsock, nbtsock->sock);

        nbtsock->idr = idr_init(nbtsock);
        if (nbtsock->idr == NULL) goto failed;

        nbtsock->send_queue = NULL;
        nbtsock->num_pending = 0;
        nbtsock->incoming.handler = NULL;
        nbtsock->unexpected.handler = NULL;

        nbtsock->fde = event_add_fd(nbtsock->event_ctx, nbtsock,
                                    socket_get_fd(nbtsock->sock), 0,
                                    nbt_name_socket_handler, nbtsock);

        return nbtsock;

failed:
        talloc_free(nbtsock);
        return NULL;
}

/*
  send off a nbt name request
*/
struct nbt_name_request *nbt_name_request_send(struct nbt_name_socket *nbtsock,
                                               struct socket_address *dest,
                                               struct nbt_name_packet *request,
                                               int timeout, int retries,
                                               bool allow_multiple_replies)
{
        struct nbt_name_request *req;
        int id;
        enum ndr_err_code ndr_err;

        req = talloc_zero(nbtsock, struct nbt_name_request);
        if (req == NULL) goto failed;

        req->nbtsock                = nbtsock;
        req->allow_multiple_replies = allow_multiple_replies;
        req->state                  = NBT_REQUEST_SEND;
        req->is_reply               = false;
        req->timeout                = timeout;
        req->num_retries            = retries;
        req->dest                   = dest;
        if (talloc_reference(req, dest) == NULL) goto failed;

        /* we select a random transaction id unless the user supplied one */
        if (request->name_trn_id == 0) {
                id = idr_get_new_random(req->nbtsock->idr, req, UINT16_MAX);
        } else {
                if (idr_find(req->nbtsock->idr, request->name_trn_id)) goto failed;
                id = idr_get_new_above(req->nbtsock->idr, req, request->name_trn_id,
                                       UINT16_MAX);
        }
        if (id == -1) goto failed;

        request->name_trn_id = id;
        req->name_trn_id     = id;

        req->te = event_add_timed(nbtsock->event_ctx, req,
                                  timeval_current_ofs(req->timeout, 0),
                                  nbt_name_socket_timeout, req);

        talloc_set_destructor(req, nbt_name_request_destructor);

        ndr_err = ndr_push_struct_blob(&req->encoded, req,
                                       request,
                                       (ndr_push_flags_fn_t)ndr_push_nbt_name_packet);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) goto failed;

        DLIST_ADD_END(nbtsock->send_queue, req, struct nbt_name_request *);

        if (DEBUGLVL(10)) {
                DEBUG(10,("Queueing nbt packet to %s:%d\n",
                          req->dest->addr, req->dest->port));
                NDR_PRINT_DEBUG(nbt_name_packet, request);
        }

        EVENT_FD_WRITEABLE(nbtsock->fde);

        return req;

failed:
        talloc_free(req);
        return NULL;
}


/*
  send off a nbt name reply
*/
_PUBLIC_ NTSTATUS nbt_name_reply_send(struct nbt_name_socket *nbtsock,
                             struct socket_address *dest,
                             struct nbt_name_packet *request)
{
        struct nbt_name_request *req;
        enum ndr_err_code ndr_err;

        req = talloc_zero(nbtsock, struct nbt_name_request);
        NT_STATUS_HAVE_NO_MEMORY(req);

        req->nbtsock   = nbtsock;
        req->dest = dest;
        if (talloc_reference(req, dest) == NULL) goto failed;
        req->state     = NBT_REQUEST_SEND;
        req->is_reply = true;

        talloc_set_destructor(req, nbt_name_request_destructor);

        if (DEBUGLVL(10)) {
                NDR_PRINT_DEBUG(nbt_name_packet, request);
        }

        ndr_err = ndr_push_struct_blob(&req->encoded, req,
                                       request,
                                       (ndr_push_flags_fn_t)ndr_push_nbt_name_packet);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                talloc_free(req);
                return ndr_map_error2ntstatus(ndr_err);
        }

        DLIST_ADD_END(nbtsock->send_queue, req, struct nbt_name_request *);

        EVENT_FD_WRITEABLE(nbtsock->fde);

        return NT_STATUS_OK;

failed:
        talloc_free(req);
        return NT_STATUS_NO_MEMORY;
}

/*
  wait for a nbt request to complete
*/
NTSTATUS nbt_name_request_recv(struct nbt_name_request *req)
{
        if (!req) return NT_STATUS_NO_MEMORY;

        while (req->state < NBT_REQUEST_DONE) {
                if (event_loop_once(req->nbtsock->event_ctx) != 0) {
                        req->state = NBT_REQUEST_ERROR;
                        req->status = NT_STATUS_UNEXPECTED_NETWORK_ERROR;
                        break;
                }
        }
        return req->status;
}


/*
  setup a handler for incoming requests
*/
_PUBLIC_ NTSTATUS nbt_set_incoming_handler(struct nbt_name_socket *nbtsock,
                                  void (*handler)(struct nbt_name_socket *, struct nbt_name_packet *,
                                                  struct socket_address *),
                                  void *private_data)
{
        nbtsock->incoming.handler = handler;
        nbtsock->incoming.private_data = private_data;
        EVENT_FD_READABLE(nbtsock->fde);
        return NT_STATUS_OK;
}

/*
  setup a handler for unexpected requests
*/
NTSTATUS nbt_set_unexpected_handler(struct nbt_name_socket *nbtsock,
                                    void (*handler)(struct nbt_name_socket *, struct nbt_name_packet *,
                                                    struct socket_address *),
                                    void *private_data)
{
        nbtsock->unexpected.handler = handler;
        nbtsock->unexpected.private_data = private_data;
        EVENT_FD_READABLE(nbtsock->fde);
        return NT_STATUS_OK;
}

/*
  turn a NBT rcode into a NTSTATUS
*/
_PUBLIC_ NTSTATUS nbt_rcode_to_ntstatus(uint8_t rcode)
{
        int i;
        struct {
                enum nbt_rcode rcode;
                NTSTATUS status;
        } map[] = {
                { NBT_RCODE_FMT, NT_STATUS_INVALID_PARAMETER },
                { NBT_RCODE_SVR, NT_STATUS_SERVER_DISABLED },
                { NBT_RCODE_NAM, NT_STATUS_OBJECT_NAME_NOT_FOUND },
                { NBT_RCODE_IMP, NT_STATUS_NOT_SUPPORTED },
                { NBT_RCODE_RFS, NT_STATUS_ACCESS_DENIED },
                { NBT_RCODE_ACT, NT_STATUS_ADDRESS_ALREADY_EXISTS },
                { NBT_RCODE_CFT, NT_STATUS_CONFLICTING_ADDRESSES }
        };
        for (i=0;i<ARRAY_SIZE(map);i++) {
                if (map[i].rcode == rcode) {
                        return map[i].status;
                }
        }
        return NT_STATUS_UNSUCCESSFUL;
}