source: vendor/current/source4/echo_server/echo_server.c@ 740

/*
   Unix SMB/CIFS implementation.

   Echo server service example

   Copyright (C) 2010 Kai Blin  <kai@samba.org>

   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 "echo_server/echo_server.h"
/* Get at the config file settings */
#include "param/param.h"
/* This defines task_server_terminate */
#include "smbd/process_model.h"
/* We get load_interfaces from here */
#include "socket/netif.h"
/* NTSTATUS-related stuff */
#include "libcli/util/ntstatus.h"
/* tsocket-related functions */
#include "lib/tsocket/tsocket.h"

/* Structure to hold an echo server socket */
struct echo_socket {
        /* This can come handy for the task struct in there */
        struct echo_server *echo;
        struct tsocket_address *local_address;
};

/* Structure to hold udp socket */
struct echo_udp_socket {
        struct echo_socket *echo_socket;
        struct tdgram_context *dgram;
        struct tevent_queue *send_queue;
};

/*
 * Main processing function.
 *
 * This is the start of the package processing.
 * In the echo server it doesn't do much, but for more complicated servers,
 * your code goes here (or at least is called from here.
 */
static NTSTATUS echo_process(struct echo_server *echo,
                             TALLOC_CTX *mem_ctx,
                             DATA_BLOB *in,
                             DATA_BLOB *out)
{
        uint8_t *buf = talloc_memdup(mem_ctx, in->data, in->length);
        NT_STATUS_HAVE_NO_MEMORY(buf);

        out->data = buf;
        out->length = in->length;

        return NT_STATUS_OK;
}

/* Structure keeping track of a single UDP echo server call */
struct echo_udp_call {
        /* The UDP packet came from here, our reply goes there as well */
        struct tsocket_address *src;
        DATA_BLOB in;
        DATA_BLOB out;
};

/** Prototype of the send callback */
static void echo_udp_call_sendto_done(struct tevent_req *subreq);

/* Callback to receive UDP packets */
static void echo_udp_call_loop(struct tevent_req *subreq)
{
        /*
         * Our socket structure is the callback data. Get it in a
         * type-safe way
         */
        struct echo_udp_socket *sock = tevent_req_callback_data(subreq,
                                       struct echo_udp_socket);
        struct echo_udp_call *call;
        uint8_t *buf;
        ssize_t len;
        NTSTATUS status;
        int sys_errno;

        call = talloc(sock, struct echo_udp_call);
        if (call == NULL) {
                goto done;
        }

        len = tdgram_recvfrom_recv(subreq, &sys_errno, call, &buf, &call->src);
        TALLOC_FREE(subreq);
        if (len == -1) {
                TALLOC_FREE(call);
                goto done;
        }

        call->in.data = buf;
        call->in.length = len;

        DEBUG(10, ("Received echo UDP packet of %lu bytes from %s\n",
                  (long)len, tsocket_address_string(call->src, call)));

        /* Handle the data coming in and compute the reply */
        status = echo_process(sock->echo_socket->echo, call,
                              &call->in, &call->out);
        if (!NT_STATUS_IS_OK(status)) {
                TALLOC_FREE(call);
                DEBUG(0, ("echo_process returned %s\n",
                          nt_errstr(status)));
                goto done;
        }

        /* I said the task struct would come in handy. */
        subreq = tdgram_sendto_queue_send(call,
                                sock->echo_socket->echo->task->event_ctx,
                                sock->dgram,
                                sock->send_queue,
                                call->out.data,
                                call->out.length,
                                call->src);
        if (subreq == NULL) {
                TALLOC_FREE(call);
                goto done;
        }

        tevent_req_set_callback(subreq, echo_udp_call_sendto_done, call);

done:
        /* Now loop for the next incoming UDP packet, the async way */
        subreq = tdgram_recvfrom_send(sock,
                                sock->echo_socket->echo->task->event_ctx,
                                sock->dgram);
        if (subreq == NULL) {
                task_server_terminate(sock->echo_socket->echo->task,
                                      "no memory for tdgram_recvfrom_send",
                                      true);
                return;
        }
        tevent_req_set_callback(subreq, echo_udp_call_loop, sock);
}

/* Callback to send UDP replies */
static void echo_udp_call_sendto_done(struct tevent_req *subreq)
{
        struct echo_udp_call *call = tevent_req_callback_data(subreq,
                                     struct echo_udp_call);
        ssize_t ret;
        int sys_errno;

        ret = tdgram_sendto_queue_recv(subreq, &sys_errno);

        /*
         * We don't actually care about the error, just get on with our life.
         * We already set a new echo_udp_call_loop callback already, so we're
         * almost done, just some memory to free.
         */
        TALLOC_FREE(call);
}

/* Start listening on a given address */
static NTSTATUS echo_add_socket(struct echo_server *echo,
                                const struct model_ops *ops,
                                const char *name,
                                const char *address,
                                uint16_t port)
{
        struct echo_socket *echo_socket;
        struct echo_udp_socket *echo_udp_socket;
        struct tevent_req *udpsubreq;
        NTSTATUS status;
        int ret;

        echo_socket = talloc(echo, struct echo_socket);
        NT_STATUS_HAVE_NO_MEMORY(echo_socket);

        echo_socket->echo = echo;

        /*
         * Initialize the tsocket_address.
         * The nifty part is the "ip" string. This tells tsocket to autodetect
         * ipv4 or ipv6 based on the IP address string passed.
         */
        ret = tsocket_address_inet_from_strings(echo_socket, "ip",
                                                address, port,
                                                &echo_socket->local_address);
        if (ret != 0) {
                status = map_nt_error_from_unix(errno);
                return status;
        }

        /* Now set up the udp socket */
        echo_udp_socket = talloc(echo_socket, struct echo_udp_socket);
        NT_STATUS_HAVE_NO_MEMORY(echo_udp_socket);

        echo_udp_socket->echo_socket = echo_socket;

        ret = tdgram_inet_udp_socket(echo_socket->local_address,
                                     NULL,
                                     echo_udp_socket,
                                     &echo_udp_socket->dgram);
        if (ret != 0) {
                status = map_nt_error_from_unix(errno);
                DEBUG(0, ("Failed to bind to %s:%u UDP - %s\n",
                          address, port, nt_errstr(status)));
                return status;
        }

        /*
         * We set up a send queue so we can have multiple UDP packets in flight
         */
        echo_udp_socket->send_queue = tevent_queue_create(echo_udp_socket,
                                                        "echo_udp_send_queue");
        NT_STATUS_HAVE_NO_MEMORY(echo_udp_socket->send_queue);

        /*
         * To handle the UDP requests, set up a new tevent request as a
         * subrequest of the current one.
         */
        udpsubreq = tdgram_recvfrom_send(echo_udp_socket,
                                         echo->task->event_ctx,
                                         echo_udp_socket->dgram);
        NT_STATUS_HAVE_NO_MEMORY(udpsubreq);
        tevent_req_set_callback(udpsubreq, echo_udp_call_loop, echo_udp_socket);

        return NT_STATUS_OK;
}

/* Set up the listening sockets */
static NTSTATUS echo_startup_interfaces(struct echo_server *echo,
                                        struct loadparm_context *lp_ctx,
                                        struct interface *ifaces)
{
        const struct model_ops *model_ops;
        int num_interfaces;
        TALLOC_CTX *tmp_ctx = talloc_new(echo);
        NTSTATUS status;
        int i;

        /*
         * Samba allows subtask to set their own process model.
         * Available models currently are:
         * - onefork  (forks exactly one child process)
         * - prefork  (keep a couple of child processes around)
         * - single   (only run a single process)
         * - standard (fork one subprocess per incoming connection)
         * - thread   (use threads instead of forks)
         *
         * For the echo server, the "single" process model works fine,
         * you probably don't want to use the thread model unless you really
         * know what you're doing.
         */

        model_ops = process_model_startup("single");
        if (model_ops == NULL) {
                DEBUG(0, ("Can't find 'single' proces model_ops\n"));
                return NT_STATUS_INTERNAL_ERROR;
        }

        num_interfaces = iface_count(ifaces);

        for(i=0; i<num_interfaces; i++) {
                const char *address = talloc_strdup(tmp_ctx, iface_n_ip(ifaces, i));

                status = echo_add_socket(echo, model_ops, "echo", address, ECHO_SERVICE_PORT);
                NT_STATUS_NOT_OK_RETURN(status);
        }

        TALLOC_FREE(tmp_ctx);
        return NT_STATUS_OK;
}


/* Do the basic task initialization, check if the task should run */

static void echo_task_init(struct task_server *task)
{
        struct interface *ifaces;
        struct echo_server *echo;
        NTSTATUS status;

        /*
         * For the purpose of the example, let's only start the server in DC
         * and standalone modes, and not as a member server.
         */
        switch(lpcfg_server_role(task->lp_ctx)) {
        case ROLE_STANDALONE:
                /* Yes, we want to run the echo server */
                break;
        case ROLE_DOMAIN_MEMBER:
                task_server_terminate(task, "echo: Not starting echo server " \
                                      "for domain members", false);
                return;
        case ROLE_DOMAIN_CONTROLLER:
                /* Yes, we want to run the echo server */
                break;
        }

        load_interfaces(task, lpcfg_interfaces(task->lp_ctx), &ifaces);

        if (iface_count(ifaces) == 0) {
                task_server_terminate(task,
                                      "echo: No network interfaces configured",
                                      false);
                return;
        }

        task_server_set_title(task, "task[echo]");

        echo = talloc_zero(task, struct echo_server);
        if (echo == NULL) {
                task_server_terminate(task, "echo: Out of memory", true);
                return;
        }

        echo->task = task;

        status = echo_startup_interfaces(echo, task->lp_ctx, ifaces);
        if (!NT_STATUS_IS_OK(status)) {
                task_server_terminate(task, "echo: Failed to set up interfaces",
                                      true);
                return;
        }
}

/*
 * Register this server service with the main samba process.
 *
 * This is the function you need to put into the wscript_build file as
 * init_function. All the real work happens in "echo_task_init" above.
 */
NTSTATUS server_service_echo_init(void)
{
        return register_server_service("echo", echo_task_init);
}