source4/echo_server/echo_server.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Echo server service example
   5
   6    Copyright (C) 2010 Kai Blin  <kai@samba.org>
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "echo_server/echo_server.h"
  24 /* Get at the config file settings */
  25 #include "param/param.h"
  26 /* This defines task_server_terminate */
  27 #include "smbd/process_model.h"
  28 /* We get load_interfaces from here */
  29 #include "socket/netif.h"
  30 /* NTSTATUS-related stuff */
  31 #include "libcli/util/ntstatus.h"
  32 /* tsocket-related functions */
  33 #include "lib/tsocket/tsocket.h"
  34
  35 /* Structure to hold an echo server socket */
  36 struct echo_socket {
  37         /* This can come handy for the task struct in there */
  38         struct echo_server *echo;
  39         struct tsocket_address *local_address;
  40 };
  41
  42 /* Structure to hold udp socket */
  43 struct echo_udp_socket {
  44         struct echo_socket *echo_socket;
  45         struct tdgram_context *dgram;
  46         struct tevent_queue *send_queue;
  47 };
  48
  49 /*
  50  * Main processing function.
  51  *
  52  * This is the start of the package processing.
  53  * In the echo server it doesn't do much, but for more complicated servers,
  54  * your code goes here (or at least is called from here.
  55  */
  56 static NTSTATUS echo_process(struct echo_server *echo,
  57                              TALLOC_CTX *mem_ctx,
  58                              DATA_BLOB *in,
  59                              DATA_BLOB *out)
  60 {
  61         uint8_t *buf = talloc_memdup(mem_ctx, in->data, in->length);
  62         NT_STATUS_HAVE_NO_MEMORY(buf);
  63
  64         out->data = buf;
  65         out->length = in->length;
  66
  67         return NT_STATUS_OK;
  68 }
  69
  70 /* Structure keeping track of a single UDP echo server call */
  71 struct echo_udp_call {
  72         /* The UDP packet came from here, our reply goes there as well */
  73         struct tsocket_address *src;
  74         DATA_BLOB in;
  75         DATA_BLOB out;
  76 };
  77
  78 /** Prototype of the send callback */
  79 static void echo_udp_call_sendto_done(struct tevent_req *subreq);
  80
  81 /* Callback to receive UDP packets */
  82 static void echo_udp_call_loop(struct tevent_req *subreq)
  83 {
  84         /*
  85          * Our socket structure is the callback data. Get it in a
  86          * type-safe way
  87          */
  88         struct echo_udp_socket *sock = tevent_req_callback_data(subreq,
  89                                        struct echo_udp_socket);
  90         struct echo_udp_call *call;
  91         uint8_t *buf;
  92         ssize_t len;
  93         NTSTATUS status;
  94         int sys_errno;
  95
  96         call = talloc(sock, struct echo_udp_call);
  97         if (call == NULL) {
  98                 goto done;
  99         }
 100
 101         len = tdgram_recvfrom_recv(subreq, &sys_errno, call, &buf, &call->src);
 102         TALLOC_FREE(subreq);
 103         if (len == -1) {
 104                 TALLOC_FREE(call);
 105                 goto done;
 106         }
 107
 108         call->in.data = buf;
 109         call->in.length = len;
 110
 111         DEBUG(10, ("Received echo UDP packet of %lu bytes from %s\n",
 112                   (long)len, tsocket_address_string(call->src, call)));
 113
 114         /* Handle the data coming in and compute the reply */
 115         status = echo_process(sock->echo_socket->echo, call,
 116                               &call->in, &call->out);
 117         if (!NT_STATUS_IS_OK(status)) {
 118                 TALLOC_FREE(call);
 119                 DEBUG(0, ("echo_process returned %s\n",
 120                           nt_errstr(status)));
 121                 goto done;
 122         }
 123
 124         /* I said the task struct would come in handy. */
 125         subreq = tdgram_sendto_queue_send(call,
 126                                 sock->echo_socket->echo->task->event_ctx,
 127                                 sock->dgram,
 128                                 sock->send_queue,
 129                                 call->out.data,
 130                                 call->out.length,
 131                                 call->src);
 132         if (subreq == NULL) {
 133                 TALLOC_FREE(call);
 134                 goto done;
 135         }
 136
 137         tevent_req_set_callback(subreq, echo_udp_call_sendto_done, call);
 138
 139 done:
 140         /* Now loop for the next incoming UDP packet, the async way */
 141         subreq = tdgram_recvfrom_send(sock,
 142                                 sock->echo_socket->echo->task->event_ctx,
 143                                 sock->dgram);
 144         if (subreq == NULL) {
 145                 task_server_terminate(sock->echo_socket->echo->task,
 146                                       "no memory for tdgram_recvfrom_send",
 147                                       true);
 148                 return;
 149         }
 150         tevent_req_set_callback(subreq, echo_udp_call_loop, sock);
 151 }
 152
 153 /* Callback to send UDP replies */
 154 static void echo_udp_call_sendto_done(struct tevent_req *subreq)
 155 {
 156         struct echo_udp_call *call = tevent_req_callback_data(subreq,
 157                                      struct echo_udp_call);
 158         ssize_t ret;
 159         int sys_errno;
 160
 161         ret = tdgram_sendto_queue_recv(subreq, &sys_errno);
 162
 163         /*
 164          * We don't actually care about the error, just get on with our life.
 165          * We already set a new echo_udp_call_loop callback already, so we're
 166          * almost done, just some memory to free.
 167          */
 168         TALLOC_FREE(call);
 169 }
 170
 171 /* Start listening on a given address */
 172 static NTSTATUS echo_add_socket(struct echo_server *echo,
 173                                 const struct model_ops *ops,
 174                                 const char *name,
 175                                 const char *address,
 176                                 uint16_t port)
 177 {
 178         struct echo_socket *echo_socket;
 179         struct echo_udp_socket *echo_udp_socket;
 180         struct tevent_req *udpsubreq;
 181         NTSTATUS status;
 182         int ret;
 183
 184         echo_socket = talloc(echo, struct echo_socket);
 185         NT_STATUS_HAVE_NO_MEMORY(echo_socket);
 186
 187         echo_socket->echo = echo;
 188
 189         /*
 190          * Initialize the tsocket_address.
 191          * The nifty part is the "ip" string. This tells tsocket to autodetect
 192          * ipv4 or ipv6 based on the IP address string passed.
 193          */
 194         ret = tsocket_address_inet_from_strings(echo_socket, "ip",
 195                                                 address, port,
 196                                                 &echo_socket->local_address);
 197         if (ret != 0) {
 198                 status = map_nt_error_from_unix(errno);
 199                 return status;
 200         }
 201
 202         /* Now set up the udp socket */
 203         echo_udp_socket = talloc(echo_socket, struct echo_udp_socket);
 204         NT_STATUS_HAVE_NO_MEMORY(echo_udp_socket);
 205
 206         echo_udp_socket->echo_socket = echo_socket;
 207
 208         ret = tdgram_inet_udp_socket(echo_socket->local_address,
 209                                      NULL,
 210                                      echo_udp_socket,
 211                                      &echo_udp_socket->dgram);
 212         if (ret != 0) {
 213                 status = map_nt_error_from_unix(errno);
 214                 DEBUG(0, ("Failed to bind to %s:%u UDP - %s\n",
 215                           address, port, nt_errstr(status)));
 216                 return status;
 217         }
 218
 219         /*
 220          * We set up a send queue so we can have multiple UDP packets in flight
 221          */
 222         echo_udp_socket->send_queue = tevent_queue_create(echo_udp_socket,
 223                                                         "echo_udp_send_queue");
 224         NT_STATUS_HAVE_NO_MEMORY(echo_udp_socket->send_queue);
 225
 226         /*
 227          * To handle the UDP requests, set up a new tevent request as a
 228          * subrequest of the current one.
 229          */
 230         udpsubreq = tdgram_recvfrom_send(echo_udp_socket,
 231                                          echo->task->event_ctx,
 232                                          echo_udp_socket->dgram);
 233         NT_STATUS_HAVE_NO_MEMORY(udpsubreq);
 234         tevent_req_set_callback(udpsubreq, echo_udp_call_loop, echo_udp_socket);
 235
 236         return NT_STATUS_OK;
 237 }
 238
 239 /* Set up the listening sockets */
 240 static NTSTATUS echo_startup_interfaces(struct echo_server *echo,
 241                                         struct loadparm_context *lp_ctx,
 242                                         struct interface *ifaces)
 243 {
 244         const struct model_ops *model_ops;
 245         int num_interfaces;
 246         TALLOC_CTX *tmp_ctx = talloc_new(echo);
 247         NTSTATUS status;
 248         int i;
 249
 250         /*
 251          * Samba allows subtask to set their own process model.
 252          * Available models currently are:
 253          * - onefork  (forks exactly one child process)
 254          * - prefork  (keep a couple of child processes around)
 255          * - single   (only run a single process)
 256          * - standard (fork one subprocess per incoming connection)
 257          * - thread   (use threads instead of forks)
 258          *
 259          * For the echo server, the "single" process model works fine,
 260          * you probably don't want to use the thread model unless you really
 261          * know what you're doing.
 262          */
 263
 264         model_ops = process_model_startup("single");
 265         if (model_ops == NULL) {
 266                 DEBUG(0, ("Can't find 'single' proces model_ops\n"));
 267                 return NT_STATUS_INTERNAL_ERROR;
 268         }
 269
 270         num_interfaces = iface_count(ifaces);
 271
 272         for(i=0; i<num_interfaces; i++) {
 273                 const char *address = talloc_strdup(tmp_ctx, iface_n_ip(ifaces, i));
 274
 275                 status = echo_add_socket(echo, model_ops, "echo", address, ECHO_SERVICE_PORT);
 276                 NT_STATUS_NOT_OK_RETURN(status);
 277         }
 278
 279         TALLOC_FREE(tmp_ctx);
 280         return NT_STATUS_OK;
 281 }
 282
 283
 284 /* Do the basic task initialization, check if the task should run */
 285
 286 static void echo_task_init(struct task_server *task)
 287 {
 288         struct interface *ifaces;
 289         struct echo_server *echo;
 290         NTSTATUS status;
 291
 292         /*
 293          * For the purpose of the example, let's only start the server in DC
 294          * and standalone modes, and not as a member server.
 295          */
 296         switch(lpcfg_server_role(task->lp_ctx)) {
 297         case ROLE_STANDALONE:
 298                 /* Yes, we want to run the echo server */
 299                 break;
 300         case ROLE_DOMAIN_MEMBER:
 301                 task_server_terminate(task, "echo: Not starting echo server " \
 302                                       "for domain members", false);
 303                 return;
 304         case ROLE_DOMAIN_CONTROLLER:
 305                 /* Yes, we want to run the echo server */
 306                 break;
 307         }
 308
 309         load_interfaces(task, lpcfg_interfaces(task->lp_ctx), &ifaces);
 310
 311         if (iface_count(ifaces) == 0) {
 312                 task_server_terminate(task,
 313                                       "echo: No network interfaces configured",
 314                                       false);
 315                 return;
 316         }
 317
 318         task_server_set_title(task, "task[echo]");
 319
 320         echo = talloc_zero(task, struct echo_server);
 321         if (echo == NULL) {
 322                 task_server_terminate(task, "echo: Out of memory", true);
 323                 return;
 324         }
 325
 326         echo->task = task;
 327
 328         status = echo_startup_interfaces(echo, task->lp_ctx, ifaces);
 329         if (!NT_STATUS_IS_OK(status)) {
 330                 task_server_terminate(task, "echo: Failed to set up interfaces",
 331                                       true);
 332                 return;
 333         }
 334 }
 335
 336 /*
 337  * Register this server service with the main samba process.
 338  *
 339  * This is the function you need to put into the wscript_build file as
 340  * init_function. All the real work happens in "echo_task_init" above.
 341  */
 342 NTSTATUS server_service_echo_init(void)
 343 {
 344         return register_server_service("echo", echo_task_init);
 345 }