source: vendor/3.5.7/source4/libcli/dgram/dgramsocket.c

/* 
   Unix SMB/CIFS implementation.

   low level socket handling for nbt dgram requests (UDP138)

   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/dgram/libdgram.h"
#include "lib/socket/socket.h"
#include "librpc/gen_ndr/ndr_nbt.h"


/*
  handle recv events on a nbt dgram socket
*/
static void dgm_socket_recv(struct nbt_dgram_socket *dgmsock)
{
        TALLOC_CTX *tmp_ctx = talloc_new(dgmsock);
        NTSTATUS status;
        struct socket_address *src;
        DATA_BLOB blob;
        size_t nread, dsize;
        struct nbt_dgram_packet *packet;
        const char *mailslot_name;
        enum ndr_err_code ndr_err;

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

        DEBUG(2,("Received dgram packet of length %d from %s:%d\n", 
                 (int)blob.length, src->addr, src->port));

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

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

        /* if this is a mailslot message, then see if we can dispatch it to a handler */
        mailslot_name = dgram_mailslot_name(packet);
        if (mailslot_name) {
                struct dgram_mailslot_handler *dgmslot;
                dgmslot = dgram_mailslot_find(dgmsock, mailslot_name);
                if (dgmslot) {
                        dgmslot->handler(dgmslot, packet, src);
                } else {
                        DEBUG(2,("No mailslot handler for '%s'\n", mailslot_name));
                }
        } else {
                /* dispatch if there is a general handler */
                if (dgmsock->incoming.handler) {
                        dgmsock->incoming.handler(dgmsock, packet, src);
                }
        }

        talloc_free(tmp_ctx);
}


/*
  handle send events on a nbt dgram socket
*/
static void dgm_socket_send(struct nbt_dgram_socket *dgmsock)
{
        struct nbt_dgram_request *req;
        NTSTATUS status;

        while ((req = dgmsock->send_queue)) {
                size_t len;
                
                len = req->encoded.length;
                status = socket_sendto(dgmsock->sock, &req->encoded, &len,
                                       req->dest);
                if (NT_STATUS_IS_ERR(status)) {
                        DEBUG(3,("Failed to send datagram of length %u to %s:%d: %s\n",
                                 (unsigned)req->encoded.length, req->dest->addr, req->dest->port, 
                                 nt_errstr(status)));
                        DLIST_REMOVE(dgmsock->send_queue, req);
                        talloc_free(req);
                        continue;
                }

                if (!NT_STATUS_IS_OK(status)) return;

                DLIST_REMOVE(dgmsock->send_queue, req);
                talloc_free(req);
        }

        EVENT_FD_NOT_WRITEABLE(dgmsock->fde);
        return;
}


/*
  handle fd events on a nbt_dgram_socket
*/
static void dgm_socket_handler(struct tevent_context *ev, struct tevent_fd *fde,
                               uint16_t flags, void *private_data)
{
        struct nbt_dgram_socket *dgmsock = talloc_get_type(private_data,
                                                           struct nbt_dgram_socket);
        if (flags & EVENT_FD_WRITE) {
                dgm_socket_send(dgmsock);
        } 
        if (flags & EVENT_FD_READ) {
                dgm_socket_recv(dgmsock);
        }
}

/*
  initialise a nbt_dgram_socket. The event_ctx is optional, if provided
  then operations will use that event context
*/
struct nbt_dgram_socket *nbt_dgram_socket_init(TALLOC_CTX *mem_ctx, 
                                              struct tevent_context *event_ctx,
                                              struct smb_iconv_convenience *iconv_convenience)
{
        struct nbt_dgram_socket *dgmsock;
        NTSTATUS status;

        dgmsock = talloc(mem_ctx, struct nbt_dgram_socket);
        if (dgmsock == NULL) goto failed;

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

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

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

        talloc_steal(dgmsock, dgmsock->sock);

        dgmsock->fde = event_add_fd(dgmsock->event_ctx, dgmsock, 
                                    socket_get_fd(dgmsock->sock), 0,
                                    dgm_socket_handler, dgmsock);

        dgmsock->send_queue = NULL;
        dgmsock->incoming.handler = NULL;
        dgmsock->mailslot_handlers = NULL;
        dgmsock->iconv_convenience = iconv_convenience;
        
        return dgmsock;

failed:
        talloc_free(dgmsock);
        return NULL;
}


/*
  setup a handler for generic incoming requests
*/
NTSTATUS dgram_set_incoming_handler(struct nbt_dgram_socket *dgmsock,
                                    void (*handler)(struct nbt_dgram_socket *, 
                                                    struct nbt_dgram_packet *, 
                                                    struct socket_address *),
                                    void *private_data)
{
        dgmsock->incoming.handler = handler;
        dgmsock->incoming.private_data = private_data;
        EVENT_FD_READABLE(dgmsock->fde);
        return NT_STATUS_OK;
}


/*
  queue a datagram for send
*/
NTSTATUS nbt_dgram_send(struct nbt_dgram_socket *dgmsock,
                        struct nbt_dgram_packet *packet,
                        struct socket_address *dest)
{
        struct nbt_dgram_request *req;
        NTSTATUS status = NT_STATUS_NO_MEMORY;
        enum ndr_err_code ndr_err;

        req = talloc(dgmsock, struct nbt_dgram_request);
        if (req == NULL) goto failed;

        req->dest = dest;
        if (talloc_reference(req, dest) == NULL) goto failed;

        ndr_err = ndr_push_struct_blob(&req->encoded, req, dgmsock->iconv_convenience, packet,
                                      (ndr_push_flags_fn_t)ndr_push_nbt_dgram_packet);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                status = ndr_map_error2ntstatus(ndr_err);
                goto failed;
        }

        DLIST_ADD_END(dgmsock->send_queue, req, struct nbt_dgram_request *);

        EVENT_FD_WRITEABLE(dgmsock->fde);

        return NT_STATUS_OK;

failed:
        talloc_free(req);
        return status;
}