send_common.c

   1 /*
   2  * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file send_common.c Functions used by more than one paraslash sender. */
   8
   9 #include <dirent.h>
  10 #include "para.h"
  11 #include "error.h"
  12 #include "string.h"
  13 #include "fd.h"
  14 #include "net.h"
  15 #include "list.h"
  16 #include "afh.h"
  17 #include "afs.h"
  18 #include "server.h"
  19 #include "acl.h"
  20 #include "send.h"
  21 #include "close_on_fork.h"
  22 #include "chunk_queue.h"
  23 #include "vss.h"
  24
  25 /** Clients will be kicked if there are more than that many bytes pending. */
  26 #define MAX_CQ_BYTES 40000
  27
  28 /**
  29  * Open a passive socket of given layer4 type.
  30  *
  31  * Set the resulting file descriptor to nonblocking mode and add it to the list
  32  * of fds that are being closed in the child process when the server calls
  33  * fork().
  34  *
  35  * \param l4type The transport-layer protocol.
  36  * \param port The port number.
  37  *
  38  * \return The listening fd on success, negative on errors.
  39  */
  40 static int open_sender(unsigned l4type, int port)
  41 {
  42         int fd, ret = para_listen(AF_UNSPEC, l4type, port);
  43
  44         if (ret < 0)
  45                 return ret;
  46         fd = ret;
  47         ret = mark_fd_nonblocking(fd);
  48         if (ret < 0) {
  49                 close(fd);
  50                 return ret;
  51         }
  52         add_close_on_fork_list(fd);
  53         return fd;
  54 }
  55
  56 /**
  57  * Shut down a client connected to a paraslash sender.
  58  *
  59  * \param sc The client to shut down.
  60  * \param ss The sender whose clients are to be shut down.
  61  *
  62  * Close the file descriptor given by \a sc, remove it from the close-on-fork
  63  * list, destroy the chunk queue of this client, delete the client from the
  64  * list of connected clients and free the sender_client struct.
  65  */
  66 void shutdown_client(struct sender_client *sc, struct sender_status *ss)
  67 {
  68         PARA_INFO_LOG("shutting down %s on fd %d\n", sc->name, sc->fd);
  69         free(sc->name);
  70         close(sc->fd);
  71         del_close_on_fork_list(sc->fd);
  72         cq_destroy(sc->cq);
  73         list_del(&sc->node);
  74         free(sc->private_data);
  75         free(sc);
  76         ss->num_clients--;
  77 }
  78
  79 void shutdown_clients(struct sender_status *ss)
  80 {
  81         struct sender_client *sc, *tmp;
  82         list_for_each_entry_safe(sc, tmp, &ss->client_list, node)
  83                 shutdown_client(sc, ss);
  84 }
  85
  86 /**
  87  * Write a buffer to a non-blocking file descriptor.
  88  *
  89  * \param fd The file descriptor.
  90  * \param buf the buffer to write.
  91  * \param len the number of bytes of \a buf.
  92  * \param max_bytes_per_write Do not write more than that many bytes at once.
  93  *
  94  * If \a max_bytes_per_write is non-zero, do not send more than that many bytes
  95  * per write().
  96  *
  97  * EAGAIN is not considered an error condition.  For example CCID3 has a
  98  * sending wait queue which fills up and is emptied asynchronously. The EAGAIN
  99  * case means that there is currently no space in the wait queue, but this can
 100  * change at any moment.
 101  *
 102  * \return Negative on errors, number of bytes written else.
 103  */
 104 static int write_nonblock(int fd, const char *buf, size_t len,
 105                 size_t max_bytes_per_write)
 106 {
 107         size_t written = 0;
 108         int ret = 0;
 109
 110         while (written < len) {
 111                 size_t num = len - written;
 112
 113                 if (max_bytes_per_write && max_bytes_per_write < num)
 114                         num = max_bytes_per_write;
 115                 ret = write(fd, buf + written, num);
 116                 if (ret < 0 && errno == EAGAIN)
 117                         return written;
 118                 if (ret < 0)
 119                         return -ERRNO_TO_PARA_ERROR(errno);
 120                 written += ret;
 121         }
 122         return written;
 123 }
 124
 125 static int queue_chunk_or_shutdown(struct sender_client *sc,
 126                 struct sender_status *ss, const char *buf, size_t num_bytes)
 127 {
 128         int ret = cq_enqueue(sc->cq, buf, num_bytes);
 129         if (ret < 0)
 130                 shutdown_client(sc, ss);
 131         return ret;
 132 }
 133
 134 /* return: negative on errors, zero if not everything was sent, one otherwise */
 135 static int send_queued_chunks(struct sender_client *sc,
 136                 size_t max_bytes_per_write)
 137 {
 138         struct queued_chunk *qc;
 139         while ((qc = cq_peek(sc->cq))) {
 140                 const char *buf;
 141                 size_t len;
 142                 int ret;
 143                 cq_get(qc, &buf, &len);
 144                 ret = write_nonblock(sc->fd, buf, len, max_bytes_per_write);
 145                 if (ret < 0)
 146                         return ret;
 147                 cq_update(sc->cq, ret);
 148                 if (ret != len)
 149                         return 0;
 150                 cq_dequeue(sc->cq);
 151         }
 152         return 1;
 153 }
 154
 155 /**
 156  * Send one chunk of audio data to a connected client.
 157  *
 158  * \param sc The client.
 159  * \param ss The sender.
 160  * \param max_bytes_per_write Split writes to chunks of at most that many bytes.
 161  * \param current_chunk The number of the chunk to write.
 162  * \param buf The data to write.
 163  * \param len The number of bytes of \a buf.
 164  * \param header_buf The audio file header.
 165  * \param header_len The number of bytes of \a header_buf.
 166  *
 167  * On errors, the client is shut down. If only a part of the buffer could be
 168  * written, the remainder is put into the chunk queue for that client.
 169  */
 170 void send_chunk(struct sender_client *sc, struct sender_status *ss,
 171                 size_t max_bytes_per_write, long unsigned current_chunk,
 172                 const char *buf, size_t len, const char *header_buf,
 173                 size_t header_len)
 174 {
 175         int ret;
 176
 177         if (!sc->header_sent && current_chunk) {
 178                 if (header_buf && header_len > 0) {
 179                         ret = queue_chunk_or_shutdown(sc, ss, header_buf, header_len);
 180                         if (ret < 0)
 181                                 goto out;
 182                 }
 183                 sc->header_sent = 1;
 184         }
 185         ret = send_queued_chunks(sc, max_bytes_per_write);
 186         if (ret < 0) {
 187                 shutdown_client(sc, ss);
 188                 goto out;
 189         }
 190         if (!len)
 191                 goto out;
 192         if (!ret) { /* still data left in the queue */
 193                 ret = queue_chunk_or_shutdown(sc, ss, buf, len);
 194                 goto out;
 195         }
 196         ret = write_nonblock(sc->fd, buf, len, max_bytes_per_write);
 197         if (ret < 0) {
 198                 shutdown_client(sc, ss);
 199                 goto out;
 200         }
 201         if (ret != len)
 202                 ret = queue_chunk_or_shutdown(sc, ss, buf + ret, len - ret);
 203 out:
 204         if (ret < 0)
 205                 PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 206 }
 207
 208 /**
 209  * Initialize a struct sender status.
 210  *
 211  * \param ss The struct to initialize.
 212  * \param access_arg The array of access arguments given at the command line.
 213  * \param num_access_args The number of elements in \a access_arg.
 214  * \param port The tcp or dccp port to listen on.
 215  * \param max_clients The maximal number of simultaneous connections.
 216  * \param default_deny Whether a blacklist should be used for access control.
 217  */
 218 void init_sender_status(struct sender_status *ss, char **access_arg,
 219         int num_access_args, int port, int max_clients, int default_deny)
 220 {
 221         ss->listen_fd = -1;
 222         INIT_LIST_HEAD(&ss->client_list);
 223         ss->port = port;
 224         acl_init(&ss->acl, access_arg, num_access_args);
 225         ss->num_clients = 0;
 226         ss->max_clients = max_clients;
 227         ss->default_deny = default_deny;
 228 }
 229
 230 /**
 231  * Return a string containing the current status of a sender.
 232  *
 233  * \param ss The sender.
 234  * \param name Used for printing the header line.
 235  *
 236  * \return The string printed in the "si" command.
 237  */
 238 char *get_sender_info(struct sender_status *ss, char *name)
 239 {
 240         char *clnts = NULL, *ret;
 241         struct sender_client *sc, *tmp_sc;
 242
 243         char *acl_contents = acl_get_contents(&ss->acl);
 244         list_for_each_entry_safe(sc, tmp_sc, &ss->client_list, node) {
 245                 char *tmp = make_message("%s%s ", clnts? clnts : "", sc->name);
 246                 free(clnts);
 247                 clnts = tmp;
 248         }
 249         ret = make_message(
 250                 "%s sender:\n"
 251                 "\tstatus: %s\n"
 252                 "\tport: %d\n"
 253                 "\tnumber of connected clients: %d\n"
 254                 "\tmaximal number of clients: %d%s\n"
 255                 "\tconnected clients: %s\n"
 256                 "\taccess %s list: %s\n",
 257                 name,
 258                 (ss->listen_fd >= 0)? "on" : "off",
 259                 ss->port,
 260                 ss->num_clients,
 261                 ss->max_clients,
 262                 ss->max_clients > 0? "" : " (unlimited)",
 263                 clnts? clnts : "(none)",
 264                 ss->default_deny? "allow" : "deny",
 265                 acl_contents? acl_contents : "(empty)"
 266         );
 267         free(acl_contents);
 268         free(clnts);
 269         return ret;
 270 }
 271
 272 /**
 273  * Allow connections from the given range of IP addresses.
 274  *
 275  * \param scd Contains the IP and the netmask.
 276  * \param ss The sender.
 277  *
 278  * \sa generic_com_deny().
 279  */
 280 void generic_com_allow(struct sender_command_data *scd,
 281                 struct sender_status *ss)
 282 {
 283         acl_allow(scd->addr, scd->netmask, &ss->acl, ss->default_deny);
 284 }
 285
 286 /**
 287  * Deny connections from the given range of IP addresses.
 288  *
 289  * \param scd see \ref generic_com_allow().
 290  * \param ss see \ref generic_com_allow().
 291  *
 292  * \sa generic_com_allow().
 293  */
 294 void generic_com_deny(struct sender_command_data *scd,
 295                 struct sender_status *ss)
 296 {
 297         acl_deny(scd->addr, scd->netmask, &ss->acl, ss->default_deny);
 298 }
 299
 300 /**
 301  * Activate a paraslash sender.
 302  *
 303  * \param ss The sender to activate.
 304  * \param protocol The symbolic name of the transport-layer protocol.
 305  *
 306  * \return Standard.
 307  */
 308 int generic_com_on(struct sender_status *ss, unsigned protocol)
 309 {
 310         int ret;
 311
 312         if (ss->listen_fd >= 0)
 313                 return 1;
 314         ret = open_sender(protocol, ss->port);
 315         if (ret < 0)
 316                 return ret;
 317         ss->listen_fd = ret;
 318         return 1;
 319 }
 320
 321 /**
 322  * Deactivate a paraslash sender.
 323  *
 324  * Shutdown all connected clients and stop listening on the TCP/DCCP socket.
 325  *
 326  * \param ss The sender to deactivate.
 327  *
 328  * \sa \ref del_close_on_fork_list(), shutdown_clients().
 329  */
 330 void generic_com_off(struct sender_status *ss)
 331 {
 332         if (ss->listen_fd < 0)
 333                 return;
 334         PARA_NOTICE_LOG("closing port %d\n", ss->port);
 335         close(ss->listen_fd);
 336         del_close_on_fork_list(ss->listen_fd);
 337         shutdown_clients(ss);
 338         ss->listen_fd = -1;
 339 }
 340
 341 /**
 342  * Accept a connection on the socket this server is listening on.
 343  *
 344  * \param ss The sender whose listening fd is ready for reading.
 345  *
 346  * This must be called only if the socket fd of \a ss is ready for reading.  It
 347  * calls para_accept() to accept the connection and performs the following
 348  * actions on the resulting file descriptor \a fd:
 349  *
 350  *      - Checks whether the maximal number of connections are exceeded.
 351  *      - Sets \a fd to nonblocking mode.
 352  *      - Checks the acl of the sender to find out whether connections
 353  *        are allowed from the IP of the connecting peer.
 354  *      - Increases the number of connections for this sender.
 355  *      - Creates and initializes a new chunk queue for queuing network
 356  *        packets that can not be sent immediately.
 357  *      - Allocates a new struct sender_client and fills in its \a fd, \a cq
 358  *        and \a name members.
 359  *      - Adds \a fd to the list of connected clients for this sender.
 360  *      - Adds \a fd to the list of file descriptors that should be closed
 361  *        in the child process when the server calls fork().
 362  *
 363  * \return A pointer to the allocated sender_client structure on success, \p
 364  * NULL on errors.
 365  *
 366  * \sa \ref para_accept(), \ref mark_fd_nonblocking(), \ref acl_check_access(),
 367  * \ref cq_new(), \ref add_close_on_fork_list().
 368  */
 369 struct sender_client *accept_sender_client(struct sender_status *ss)
 370 {
 371         struct sender_client *sc;
 372         int fd, ret = para_accept(ss->listen_fd, NULL, 0);
 373         if (ret < 0) {
 374                 PARA_ERROR_LOG("%s\n", para_strerror(-ret));
 375                 return NULL;
 376         }
 377         fd = ret;
 378         ret = -E_MAX_CLIENTS;
 379         if (ss->max_clients > 0 && ss->num_clients >= ss->max_clients)
 380                 goto err_out;
 381         ret = mark_fd_nonblocking(fd);
 382         if (ret < 0)
 383                 goto err_out;
 384         ret = acl_check_access(fd, &ss->acl, ss->default_deny);
 385         if (ret < 0)
 386                 goto err_out;
 387         ss->num_clients++;
 388         sc = para_calloc(sizeof(*sc));
 389         sc->fd = fd;
 390         sc->name = make_message("%s", remote_name(fd));
 391         sc->cq = cq_new(MAX_CQ_BYTES);
 392         para_list_add(&sc->node, &ss->client_list);
 393         add_close_on_fork_list(fd);
 394         PARA_INFO_LOG("accepted client #%d: %s (fd %d)\n", ss->num_clients,
 395                 sc->name, fd);
 396         return sc;
 397 err_out:
 398         PARA_WARNING_LOG("%s\n", para_strerror(-ret));
 399         close(fd);
 400         return NULL;
 401 }
 402
 403 /**
 404  * Get the generic help text.
 405  *
 406  * \return A dynamically allocated string containing the help text for
 407  * a paraslash sender.
 408  */
 409 char *generic_sender_help(void)
 410 {
 411         return make_message(
 412                 "usage: {on|off}\n"
 413                 "usage: {allow|deny} IP mask\n"
 414                 "example: allow 127.0.0.1 32\n"
 415         );
 416 }