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_interface_list 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 NTSTATUS server_service_echo_init(void);
  36
  37 /* Structure to hold an echo server socket */
  38 struct echo_socket {
  39         /* This can come handy for the task struct in there */
  40         struct echo_server *echo;
  41         struct tsocket_address *local_address;
  42 };
  43
  44 /* Structure to hold udp socket */
  45 struct echo_udp_socket {
  46         struct echo_socket *echo_socket;
  47         struct tdgram_context *dgram;
  48         struct tevent_queue *send_queue;
  49 };
  50
  51 /*
  52  * Main processing function.
  53  *
  54  * This is the start of the package processing.
  55  * In the echo server it doesn't do much, but for more complicated servers,
  56  * your code goes here (or at least is called from here.
  57  */
  58 static NTSTATUS echo_process(struct echo_server *echo,
  59                              TALLOC_CTX *mem_ctx,
  60                              DATA_BLOB *in,
  61                              DATA_BLOB *out)
  62 {
  63         uint8_t *buf = talloc_memdup(mem_ctx, in->data, in->length);
  64         NT_STATUS_HAVE_NO_MEMORY(buf);
  65
  66         out->data = buf;
  67         out->length = in->length;
  68
  69         return NT_STATUS_OK;
  70 }
  71
  72 /* Structure keeping track of a single UDP echo server call */
  73 struct echo_udp_call {
  74         /* The UDP packet came from here, our reply goes there as well */
  75         struct tsocket_address *src;
  76         DATA_BLOB in;
  77         DATA_BLOB out;
  78 };
  79
  80 /** Prototype of the send callback */
  81 static void echo_udp_call_sendto_done(struct tevent_req *subreq);
  82
  83 /* Callback to receive UDP packets */
  84 static void echo_udp_call_loop(struct tevent_req *subreq)
  85 {
  86         /*
  87          * Our socket structure is the callback data. Get it in a
  88          * type-safe way
  89          */
  90         struct echo_udp_socket *sock = tevent_req_callback_data(subreq,
  91                                        struct echo_udp_socket);
  92         struct echo_udp_call *call;
  93         uint8_t *buf;
  94         ssize_t len;
  95         NTSTATUS status;
  96         int sys_errno;
  97
  98         call = talloc(sock, struct echo_udp_call);
  99         if (call == NULL) {
 100                 goto done;
 101         }
 102
 103         len = tdgram_recvfrom_recv(subreq, &sys_errno, call, &buf, &call->src);
 104         TALLOC_FREE(subreq);
 105         if (len == -1) {
 106                 TALLOC_FREE(call);
 107                 goto done;
 108         }
 109
 110         call->in.data = buf;
 111         call->in.length = len;
 112
 113         DEBUG(10, ("Received echo UDP packet of %lu bytes from %s\n",
 114                   (long)len, tsocket_address_string(call->src, call)));
 115
 116         /* Handle the data coming in and compute the reply */
 117         status = echo_process(sock->echo_socket->echo, call,
 118                               &call->in, &call->out);
 119         if (!NT_STATUS_IS_OK(status)) {
 120                 TALLOC_FREE(call);
 121                 DEBUG(0, ("echo_process returned %s\n",
 122                           nt_errstr(status)));
 123                 goto done;
 124         }
 125
 126         /* I said the task struct would come in handy. */
 127         subreq = tdgram_sendto_queue_send(call,
 128                                 sock->echo_socket->echo->task->event_ctx,
 129                                 sock->dgram,
 130                                 sock->send_queue,
 131                                 call->out.data,
 132                                 call->out.length,
 133                                 call->src);
 134         if (subreq == NULL) {
 135                 TALLOC_FREE(call);
 136                 goto done;
 137         }
 138
 139         tevent_req_set_callback(subreq, echo_udp_call_sendto_done, call);
 140
 141 done:
 142         /* Now loop for the next incoming UDP packet, the async way */
 143         subreq = tdgram_recvfrom_send(sock,
 144                                 sock->echo_socket->echo->task->event_ctx,
 145                                 sock->dgram);
 146         if (subreq == NULL) {
 147                 task_server_terminate(sock->echo_socket->echo->task,
 148                                       "no memory for tdgram_recvfrom_send",
 149                                       true);
 150                 return;
 151         }
 152         tevent_req_set_callback(subreq, echo_udp_call_loop, sock);
 153 }
 154
 155 /* Callback to send UDP replies */
 156 static void echo_udp_call_sendto_done(struct tevent_req *subreq)
 157 {
 158         struct echo_udp_call *call = tevent_req_callback_data(subreq,
 159                                      struct echo_udp_call);
 160         ssize_t ret;
 161         int sys_errno;
 162
 163         ret = tdgram_sendto_queue_recv(subreq, &sys_errno);
 164
 165         /*
 166          * We don't actually care about the error, just get on with our life.
 167          * We already set a new echo_udp_call_loop callback already, so we're
 168          * almost done, just some memory to free.
 169          */
 170         TALLOC_FREE(call);
 171 }
 172
 173 /* Start listening on a given address */
 174 static NTSTATUS echo_add_socket(struct echo_server *echo,
 175                                 const struct model_ops *ops,
 176                                 const char *name,
 177                                 const char *address,
 178                                 uint16_t port)
 179 {
 180         struct echo_socket *echo_socket;
 181         struct echo_udp_socket *echo_udp_socket;
 182         struct tevent_req *udpsubreq;
 183         NTSTATUS status;
 184         int ret;
 185
 186         echo_socket = talloc(echo, struct echo_socket);
 187         NT_STATUS_HAVE_NO_MEMORY(echo_socket);
 188
 189         echo_socket->echo = echo;
 190
 191         /*
 192          * Initialize the tsocket_address.
 193          * The nifty part is the "ip" string. This tells tsocket to autodetect
 194          * ipv4 or ipv6 based on the IP address string passed.
 195          */
 196         ret = tsocket_address_inet_from_strings(echo_socket, "ip",
 197                                                 address, port,
 198                                                 &echo_socket->local_address);
 199         if (ret != 0) {
 200                 status = map_nt_error_from_unix_common(errno);
 201                 return status;
 202         }
 203
 204         /* Now set up the udp socket */
 205         echo_udp_socket = talloc(echo_socket, struct echo_udp_socket);
 206         NT_STATUS_HAVE_NO_MEMORY(echo_udp_socket);
 207
 208         echo_udp_socket->echo_socket = echo_socket;
 209
 210         ret = tdgram_inet_udp_socket(echo_socket->local_address,
 211                                      NULL,
 212                                      echo_udp_socket,
 213                                      &echo_udp_socket->dgram);
 214         if (ret != 0) {
 215                 status = map_nt_error_from_unix_common(errno);
 216                 DEBUG(0, ("Failed to bind to %s:%u UDP - %s\n",
 217                           address, port, nt_errstr(status)));
 218                 return status;
 219         }
 220
 221         /*
 222          * We set up a send queue so we can have multiple UDP packets in flight
 223          */
 224         echo_udp_socket->send_queue = tevent_queue_create(echo_udp_socket,
 225                                                         "echo_udp_send_queue");
 226         NT_STATUS_HAVE_NO_MEMORY(echo_udp_socket->send_queue);
 227
 228         /*
 229          * To handle the UDP requests, set up a new tevent request as a
 230          * subrequest of the current one.
 231          */
 232         udpsubreq = tdgram_recvfrom_send(echo_udp_socket,
 233                                          echo->task->event_ctx,
 234                                          echo_udp_socket->dgram);
 235         NT_STATUS_HAVE_NO_MEMORY(udpsubreq);
 236         tevent_req_set_callback(udpsubreq, echo_udp_call_loop, echo_udp_socket);
 237
 238         return NT_STATUS_OK;
 239 }
 240
 241 /* Set up the listening sockets */
 242 static NTSTATUS echo_startup_interfaces(struct echo_server *echo,
 243                                         struct loadparm_context *lp_ctx,
 244                                         struct interface *ifaces)
 245 {
 246         const struct model_ops *model_ops;
 247         int num_interfaces;
 248         TALLOC_CTX *tmp_ctx = talloc_new(echo);
 249         NTSTATUS status;
 250         int i;
 251
 252         /*
 253          * Samba allows subtask to set their own process model.
 254          * Available models currently are:
 255          * - onefork  (forks exactly one child process)
 256          * - prefork  (keep a couple of child processes around)
 257          * - single   (only run a single process)
 258          * - standard (fork one subprocess per incoming connection)
 259          * - thread   (use threads instead of forks)
 260          *
 261          * For the echo server, the "single" process model works fine,
 262          * you probably don't want to use the thread model unless you really
 263          * know what you're doing.
 264          */
 265
 266         model_ops = process_model_startup("single");
 267         if (model_ops == NULL) {
 268                 DEBUG(0, ("Can't find 'single' proces model_ops\n"));
 269                 return NT_STATUS_INTERNAL_ERROR;
 270         }
 271
 272         num_interfaces = iface_list_count(ifaces);
 273
 274         for(i=0; i<num_interfaces; i++) {
 275                 const char *address = talloc_strdup(tmp_ctx, iface_list_n_ip(ifaces, i));
 276
 277                 status = echo_add_socket(echo, model_ops, "echo", address, ECHO_SERVICE_PORT);
 278                 NT_STATUS_NOT_OK_RETURN(status);
 279         }
 280
 281         TALLOC_FREE(tmp_ctx);
 282         return NT_STATUS_OK;
 283 }
 284
 285
 286 /* Do the basic task initialization, check if the task should run */
 287
 288 static void echo_task_init(struct task_server *task)
 289 {
 290         struct interface *ifaces;
 291         struct echo_server *echo;
 292         NTSTATUS status;
 293
 294         /*
 295          * For the purpose of the example, let's only start the server in DC
 296          * and standalone modes, and not as a member server.
 297          */
 298         switch(lpcfg_server_role(task->lp_ctx)) {
 299         case ROLE_STANDALONE:
 300                 /* Yes, we want to run the echo server */
 301                 break;
 302         case ROLE_DOMAIN_MEMBER:
 303                 task_server_terminate(task, "echo: Not starting echo server " \
 304                                       "for domain members", false);
 305                 return;
 306         case ROLE_DOMAIN_CONTROLLER:
 307                 /* Yes, we want to run the echo server */
 308                 break;
 309         }
 310
 311         load_interface_list(task, task->lp_ctx, &ifaces);
 312
 313         if (iface_list_count(ifaces) == 0) {
 314                 task_server_terminate(task,
 315                                       "echo: No network interfaces configured",
 316                                       false);
 317                 return;
 318         }
 319
 320         task_server_set_title(task, "task[echo]");
 321
 322         echo = talloc_zero(task, struct echo_server);
 323         if (echo == NULL) {
 324                 task_server_terminate(task, "echo: Out of memory", true);
 325                 return;
 326         }
 327
 328         echo->task = task;
 329
 330         status = echo_startup_interfaces(echo, task->lp_ctx, ifaces);
 331         if (!NT_STATUS_IS_OK(status)) {
 332                 task_server_terminate(task, "echo: Failed to set up interfaces",
 333                                       true);
 334                 return;
 335         }
 336 }
 337
 338 /*
 339  * Register this server service with the main samba process.
 340  *
 341  * This is the function you need to put into the wscript_build file as
 342  * init_function. All the real work happens in "echo_task_init" above.
 343  */
 344 NTSTATUS server_service_echo_init(void)
 345 {
 346         return register_server_service("echo", echo_task_init);
 347 }