source: trunk/server/source3/libsmb/unexpected.c

/*
   Unix SMB/CIFS implementation.
   handle unexpected packets
   Copyright (C) Andrew Tridgell 2000

   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/util/tevent_ntstatus.h"
#include "lib/async_req/async_sock.h"
#include "libsmb/nmblib.h"

static const char *nmbd_socket_dir(void)
{
        return lp_parm_const_string(-1, "nmbd", "socket dir",
                                    get_dyn_NMBDSOCKETDIR());
}

struct nb_packet_query {
        enum packet_type type;
        size_t mailslot_namelen;
        int trn_id;
};

struct nb_packet_client;

struct nb_packet_server {
        struct tevent_context *ev;
        int listen_sock;
        int max_clients;
        int num_clients;
        struct nb_packet_client *clients;
};

struct nb_packet_client {
        struct nb_packet_client *prev, *next;
        struct nb_packet_server *server;

        enum packet_type type;
        int trn_id;
        char *mailslot_name;

        int sock;
        struct tevent_req *read_req;
        struct tevent_queue *out_queue;
};

static int nb_packet_server_destructor(struct nb_packet_server *s);
static void nb_packet_server_listener(struct tevent_context *ev,
                                      struct tevent_fd *fde,
                                      uint16_t flags,
                                      void *private_data);

NTSTATUS nb_packet_server_create(TALLOC_CTX *mem_ctx,
                                 struct tevent_context *ev,
                                 int max_clients,
                                 struct nb_packet_server **presult)
{
        struct nb_packet_server *result;
        struct tevent_fd *fde;
        NTSTATUS status;

        result = TALLOC_ZERO_P(mem_ctx, struct nb_packet_server);
        if (result == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto fail;
        }
        result->ev = ev;
        result->max_clients = max_clients;

        result->listen_sock = create_pipe_sock(
                nmbd_socket_dir(), "unexpected", 0755);
        if (result->listen_sock == -1) {
                status = map_nt_error_from_unix(errno);
                goto fail;
        }
        talloc_set_destructor(result, nb_packet_server_destructor);

        fde = tevent_add_fd(ev, result, result->listen_sock, TEVENT_FD_READ,
                            nb_packet_server_listener, result);
        if (fde == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto fail;
        }

        *presult = result;
        return NT_STATUS_OK;
fail:
        TALLOC_FREE(result);
        return status;
}

static int nb_packet_server_destructor(struct nb_packet_server *s)
{
        if (s->listen_sock != -1) {
                close(s->listen_sock);
                s->listen_sock = -1;
        }
        return 0;
}

static int nb_packet_client_destructor(struct nb_packet_client *c);
static ssize_t nb_packet_client_more(uint8_t *buf, size_t buflen,
                                     void *private_data);
static void nb_packet_got_query(struct tevent_req *req);
static void nb_packet_client_read_done(struct tevent_req *req);

static void nb_packet_server_listener(struct tevent_context *ev,
                                      struct tevent_fd *fde,
                                      uint16_t flags,
                                      void *private_data)
{
        struct nb_packet_server *server = talloc_get_type_abort(
                private_data, struct nb_packet_server);
        struct nb_packet_client *client;
        struct tevent_req *req;
        struct sockaddr_un sunaddr;
        socklen_t len;
        int sock;

        len = sizeof(sunaddr);

        sock = accept(server->listen_sock, (struct sockaddr *)(void *)&sunaddr,
                      &len);
        if (sock == -1) {
                return;
        }
        DEBUG(6,("accepted socket %d\n", sock));

        client = TALLOC_ZERO_P(server, struct nb_packet_client);
        if (client == NULL) {
                DEBUG(10, ("talloc failed\n"));
                close(sock);
                return;
        }
        client->sock = sock;
        client->server = server;
        talloc_set_destructor(client, nb_packet_client_destructor);

        client->out_queue = tevent_queue_create(
                client, "unexpected packet output");
        if (client->out_queue == NULL) {
                DEBUG(10, ("tevent_queue_create failed\n"));
                TALLOC_FREE(client);
                return;
        }

        req = read_packet_send(client, ev, client->sock,
                               sizeof(struct nb_packet_query),
                               nb_packet_client_more, NULL);
        if (req == NULL) {
                DEBUG(10, ("read_packet_send failed\n"));
                TALLOC_FREE(client);
                return;
        }
        tevent_req_set_callback(req, nb_packet_got_query, client);

        DLIST_ADD(server->clients, client);
        server->num_clients += 1;

        if (server->num_clients > server->max_clients) {
                DEBUG(10, ("Too many clients, dropping oldest\n"));

                /*
                 * no TALLOC_FREE here, don't mess with the list structs
                 */
                talloc_free(server->clients->prev);
        }
}

static ssize_t nb_packet_client_more(uint8_t *buf, size_t buflen,
                                     void *private_data)
{
        struct nb_packet_query q;
        if (buflen > sizeof(struct nb_packet_query)) {
                return 0;
        }
        /* Take care of alignment */
        memcpy(&q, buf, sizeof(q));
        if (q.mailslot_namelen > 1024) {
                DEBUG(10, ("Got invalid mailslot namelen %d\n",
                           (int)q.mailslot_namelen));
                return -1;
        }
        return q.mailslot_namelen;
}

static int nb_packet_client_destructor(struct nb_packet_client *c)
{
        if (c->sock != -1) {
                close(c->sock);
                c->sock = -1;
        }
        DLIST_REMOVE(c->server->clients, c);
        c->server->num_clients -= 1;
        return 0;
}

static void nb_packet_got_query(struct tevent_req *req)
{
        struct nb_packet_client *client = tevent_req_callback_data(
                req, struct nb_packet_client);
        struct nb_packet_query q;
        uint8_t *buf;
        ssize_t nread, nwritten;
        int err;
        char c;

        nread = read_packet_recv(req, talloc_tos(), &buf, &err);
        TALLOC_FREE(req);
        if (nread < (ssize_t)sizeof(struct nb_packet_query)) {
                DEBUG(10, ("read_packet_recv returned %d (%s)\n",
                           (int)nread,
                           (nread == -1) ? strerror(err) : "wrong length"));
                TALLOC_FREE(client);
                return;
        }

        /* Take care of alignment */
        memcpy(&q, buf, sizeof(q));

        if (nread != sizeof(struct nb_packet_query) + q.mailslot_namelen) {
                DEBUG(10, ("nb_packet_got_query: Invalid mailslot namelength\n"));
                TALLOC_FREE(client);
                return;
        }

        client->trn_id = q.trn_id;
        client->type = q.type;
        if (q.mailslot_namelen > 0) {
                client->mailslot_name = talloc_strndup(
                        client, (char *)buf + sizeof(q),
                        q.mailslot_namelen);
                if (client->mailslot_name == NULL) {
                        TALLOC_FREE(client);
                        return;
                }
        }

        /*
         * Yes, this is a blocking write of 1 byte into a unix
         * domain socket that has never been written to. Highly
         * unlikely that this actually blocks.
         */
        c = 0;
        nwritten = sys_write(client->sock, &c, sizeof(c));
        if (nwritten != sizeof(c)) {
                DEBUG(10, ("Could not write success indicator to client: %s\n",
                           strerror(errno)));
                TALLOC_FREE(client);
                return;
        }

        client->read_req = read_packet_send(client, client->server->ev,
                                            client->sock, 1, NULL, NULL);
        if (client->read_req == NULL) {
                DEBUG(10, ("Could not activate reader for client exit "
                           "detection\n"));
                TALLOC_FREE(client);
                return;
        }
        tevent_req_set_callback(client->read_req, nb_packet_client_read_done,
                                client);
}

static void nb_packet_client_read_done(struct tevent_req *req)
{
        struct nb_packet_client *client = tevent_req_callback_data(
                req, struct nb_packet_client);
        ssize_t nread;
        uint8_t *buf;
        int err;

        nread = read_packet_recv(req, talloc_tos(), &buf, &err);
        TALLOC_FREE(req);
        if (nread == 1) {
                DEBUG(10, ("Protocol error, received data on write-only "
                           "unexpected socket: 0x%2.2x\n", (*buf)));
        }
        TALLOC_FREE(client);
}

static void nb_packet_client_send(struct nb_packet_client *client,
                                  struct packet_struct *p);

void nb_packet_dispatch(struct nb_packet_server *server,
                        struct packet_struct *p)
{
        struct nb_packet_client *c;
        uint16_t trn_id;

        switch (p->packet_type) {
        case NMB_PACKET:
                trn_id = p->packet.nmb.header.name_trn_id;
                break;
        case DGRAM_PACKET:
                trn_id = p->packet.dgram.header.dgm_id;
                break;
        default:
                DEBUG(10, ("Got invalid packet type %d\n",
                           (int)p->packet_type));
                return;
        }
        for (c = server->clients; c != NULL; c = c->next) {

                if (c->type != p->packet_type) {
                        DEBUG(10, ("client expects packet %d, got %d\n",
                                   c->type, p->packet_type));
                        continue;
                }

                if (p->packet_type == NMB_PACKET) {
                        /*
                         * See if the client specified transaction
                         * ID. Filter if it did.
                         */
                        if ((c->trn_id != -1) &&
                            (c->trn_id != trn_id)) {
                                DEBUG(10, ("client expects trn %d, got %d\n",
                                           c->trn_id, trn_id));
                                continue;
                        }
                } else {
                        /*
                         * See if the client specified a mailslot
                         * name. Filter if it did.
                         */
                        if ((c->mailslot_name != NULL) &&
                            !match_mailslot_name(p, c->mailslot_name)) {
                                continue;
                        }
                }
                nb_packet_client_send(c, p);
        }
}

struct nb_packet_client_header {
        size_t len;
        enum packet_type type;
        time_t timestamp;
        struct in_addr ip;
        int port;
};

struct nb_packet_client_state {
        struct nb_packet_client *client;
        struct iovec iov[2];
        struct nb_packet_client_header hdr;
        char buf[1024];
};

static void nb_packet_client_send_done(struct tevent_req *req);

static void nb_packet_client_send(struct nb_packet_client *client,
                                  struct packet_struct *p)
{
        struct nb_packet_client_state *state;
        struct tevent_req *req;

        if (tevent_queue_length(client->out_queue) > 10) {
                /*
                 * Skip clients that don't listen anyway, some form of DoS
                 * protection
                 */
                return;
        }

        state = TALLOC_ZERO_P(client, struct nb_packet_client_state);
        if (state == NULL) {
                DEBUG(10, ("talloc failed\n"));
                return;
        }

        state->client = client;

        state->hdr.ip = p->ip;
        state->hdr.port = p->port;
        state->hdr.timestamp = p->timestamp;
        state->hdr.type = p->packet_type;
        state->hdr.len = build_packet(state->buf, sizeof(state->buf), p);

        state->iov[0].iov_base = (char *)&state->hdr;
        state->iov[0].iov_len = sizeof(state->hdr);
        state->iov[1].iov_base = state->buf;
        state->iov[1].iov_len = state->hdr.len;

        TALLOC_FREE(client->read_req);

        req = writev_send(client, client->server->ev, client->out_queue,
                          client->sock, true, state->iov, 2);
        if (req == NULL) {
                DEBUG(10, ("writev_send failed\n"));
                return;
        }
        tevent_req_set_callback(req, nb_packet_client_send_done, state);
}

static void nb_packet_client_send_done(struct tevent_req *req)
{
        struct nb_packet_client_state *state = tevent_req_callback_data(
                req, struct nb_packet_client_state);
        struct nb_packet_client *client = state->client;
        ssize_t nwritten;
        int err;

        nwritten = writev_recv(req, &err);

        TALLOC_FREE(req);
        TALLOC_FREE(state);

        if (nwritten == -1) {
                DEBUG(10, ("writev failed: %s\n", strerror(err)));
                TALLOC_FREE(client);
        }

        if (tevent_queue_length(client->out_queue) == 0) {
                client->read_req = read_packet_send(client, client->server->ev,
                                                    client->sock, 1,
                                                    NULL, NULL);
                if (client->read_req == NULL) {
                        DEBUG(10, ("Could not activate reader for client exit "
                                   "detection\n"));
                        TALLOC_FREE(client);
                        return;
                }
                tevent_req_set_callback(client->read_req,
                                        nb_packet_client_read_done,
                                        client);
        }
}

struct nb_packet_reader {
        int sock;
};

struct nb_packet_reader_state {
        struct tevent_context *ev;
        struct sockaddr_un addr;
        struct nb_packet_query query;
        const char *mailslot_name;
        struct iovec iov[2];
        char c;
        struct nb_packet_reader *reader;
};

static int nb_packet_reader_destructor(struct nb_packet_reader *r);
static void nb_packet_reader_connected(struct tevent_req *subreq);
static void nb_packet_reader_sent_query(struct tevent_req *subreq);
static void nb_packet_reader_got_ack(struct tevent_req *subreq);

struct tevent_req *nb_packet_reader_send(TALLOC_CTX *mem_ctx,
                                         struct tevent_context *ev,
                                         enum packet_type type,
                                         int trn_id,
                                         const char *mailslot_name)
{
        struct tevent_req *req, *subreq;
        struct nb_packet_reader_state *state;
        char *path;

        req = tevent_req_create(mem_ctx, &state,
                                struct nb_packet_reader_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->query.trn_id = trn_id;
        state->query.type = type;
        state->mailslot_name = mailslot_name;

        if (mailslot_name != NULL) {
                state->query.mailslot_namelen = strlen(mailslot_name);
        }

        state->reader = TALLOC_ZERO_P(state, struct nb_packet_reader);
        if (tevent_req_nomem(state->reader, req)) {
                return tevent_req_post(req, ev);
        }

        path = talloc_asprintf(talloc_tos(), "%s/%s", nmbd_socket_dir(),
                               "unexpected");
        if (tevent_req_nomem(path, req)) {
                return tevent_req_post(req, ev);
        }
        state->addr.sun_family = AF_UNIX;
        strlcpy(state->addr.sun_path, path, sizeof(state->addr.sun_path));
        TALLOC_FREE(path);

        state->reader->sock = socket(AF_UNIX, SOCK_STREAM, 0);
        if (state->reader->sock == -1) {
                tevent_req_nterror(req, map_nt_error_from_unix(errno));
                return tevent_req_post(req, ev);
        }
        talloc_set_destructor(state->reader, nb_packet_reader_destructor);

        subreq = async_connect_send(state, ev, state->reader->sock,
                                    (struct sockaddr *)(void *)&state->addr,
                                    sizeof(state->addr));
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, nb_packet_reader_connected, req);
        return req;
}

static int nb_packet_reader_destructor(struct nb_packet_reader *r)
{
        if (r->sock != -1) {
                close(r->sock);
                r->sock = -1;
        }
        return 0;
}

static void nb_packet_reader_connected(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct nb_packet_reader_state *state = tevent_req_data(
                req, struct nb_packet_reader_state);
        int res, err;
        int num_iovecs = 1;

        res = async_connect_recv(subreq, &err);
        TALLOC_FREE(subreq);
        if (res == -1) {
                DEBUG(10, ("async_connect failed: %s\n", strerror(err)));
                tevent_req_nterror(req, map_nt_error_from_unix(err));
                return;
        }

        state->iov[0].iov_base = (char *)&state->query;
        state->iov[0].iov_len = sizeof(state->query);

        if (state->mailslot_name != NULL) {
                num_iovecs = 2;
                state->iov[1].iov_base = discard_const_p(
                        char, state->mailslot_name);
                state->iov[1].iov_len = state->query.mailslot_namelen;
        }

        subreq = writev_send(state, state->ev, NULL, state->reader->sock,
                             true, state->iov, num_iovecs);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, nb_packet_reader_sent_query, req);
}

static void nb_packet_reader_sent_query(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct nb_packet_reader_state *state = tevent_req_data(
                req, struct nb_packet_reader_state);
        ssize_t written;
        int err;

        written = writev_recv(subreq, &err);
        TALLOC_FREE(subreq);
        if (written == -1) {
                tevent_req_nterror(req, map_nt_error_from_unix(err));
                return;
        }
        if (written != sizeof(state->query) + state->query.mailslot_namelen) {
                tevent_req_nterror(req, NT_STATUS_UNEXPECTED_IO_ERROR);
                return;
        }
        subreq = read_packet_send(state, state->ev, state->reader->sock,
                                  sizeof(state->c), NULL, NULL);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, nb_packet_reader_got_ack, req);
}

static void nb_packet_reader_got_ack(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct nb_packet_reader_state *state = tevent_req_data(
                req, struct nb_packet_reader_state);
        ssize_t nread;
        int err;
        uint8_t *buf;

        nread = read_packet_recv(subreq, state, &buf, &err);
        TALLOC_FREE(subreq);
        if (nread == -1) {
                DEBUG(10, ("read_packet_recv returned %s\n",
                           strerror(err)));
                tevent_req_nterror(req, map_nt_error_from_unix(err));
                return;
        }
        if (nread != sizeof(state->c)) {
                DEBUG(10, ("read = %d, expected %d\n", (int)nread,
                           (int)sizeof(state->c)));
                tevent_req_nterror(req, NT_STATUS_UNEXPECTED_IO_ERROR);
                return;
        }
        tevent_req_done(req);
}

NTSTATUS nb_packet_reader_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
                               struct nb_packet_reader **preader)
{
        struct nb_packet_reader_state *state = tevent_req_data(
                req, struct nb_packet_reader_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }
        *preader = talloc_move(mem_ctx, &state->reader);
        return NT_STATUS_OK;
}

struct nb_packet_read_state {
        struct nb_packet_client_header hdr;
        uint8_t *buf;
        size_t buflen;
};

static ssize_t nb_packet_read_more(uint8_t *buf, size_t buflen, void *p);
static void nb_packet_read_done(struct tevent_req *subreq);

struct tevent_req *nb_packet_read_send(TALLOC_CTX *mem_ctx,
                                       struct tevent_context *ev,
                                       struct nb_packet_reader *reader)
{
        struct tevent_req *req, *subreq;
        struct nb_packet_read_state *state;

        req = tevent_req_create(mem_ctx, &state, struct nb_packet_read_state);
        if (req == NULL) {
                return NULL;
        }
        subreq = read_packet_send(state, ev, reader->sock,
                                  sizeof(struct nb_packet_client_header),
                                  nb_packet_read_more, state);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, nb_packet_read_done, req);
        return req;
}

static ssize_t nb_packet_read_more(uint8_t *buf, size_t buflen, void *p)
{
        struct nb_packet_read_state *state = talloc_get_type_abort(
                p, struct nb_packet_read_state);

        if (buflen > sizeof(struct nb_packet_client_header)) {
                /*
                 * Been here, done
                 */
                return 0;
        }
        memcpy(&state->hdr, buf, sizeof(struct nb_packet_client_header));
        return state->hdr.len;
}

static void nb_packet_read_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct nb_packet_read_state *state = tevent_req_data(
                req, struct nb_packet_read_state);
        ssize_t nread;
        int err;

        nread = read_packet_recv(subreq, state, &state->buf, &err);
        if (nread == -1) {
                tevent_req_nterror(req, map_nt_error_from_unix(err));
                return;
        }
        state->buflen = nread;
        tevent_req_done(req);
}

NTSTATUS nb_packet_read_recv(struct tevent_req *req,
                             struct packet_struct **ppacket)
{
        struct nb_packet_read_state *state = tevent_req_data(
                req, struct nb_packet_read_state);
        struct nb_packet_client_header hdr;
        struct packet_struct *packet;
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }

        memcpy(&hdr, state->buf, sizeof(hdr));

        packet = parse_packet(
                (char *)state->buf + sizeof(struct nb_packet_client_header),
                state->buflen - sizeof(struct nb_packet_client_header),
                state->hdr.type, state->hdr.ip, state->hdr.port);
        if (packet == NULL) {
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }
        *ppacket = packet;
        return NT_STATUS_OK;
}