+/** The list of supported senders. */
+struct sender senders[] = {
+ {
+ .name = "http",
+ .init = http_send_init,
+ },
+ {
+ .name = "dccp",
+ .init = dccp_send_init,
+ },
+ {
+ .name = "udp",
+ .init = udp_send_init,
+ },
+ {
+ .name = NULL,
+ }
+};
+
+/** The possible states of the afs socket. */
+enum afs_socket_status {
+ /** Socket is inactive. */
+ AFS_SOCKET_READY,
+ /** Socket fd was included in the write fd set for select(). */
+ AFS_SOCKET_CHECK_FOR_WRITE,
+ /** vss wrote a request to the socket and waits for reply from afs. */
+ AFS_SOCKET_AFD_PENDING
+};
+
+/** The task structure for the virtual streaming system. */
+struct vss_task {
+ /** Copied from the -announce_time command line option. */
+ struct timeval announce_tv;
+ /** End of the announcing interval. */
+ struct timeval data_send_barrier;
+ /** End of the EOF interval. */
+ struct timeval eof_barrier;
+ /** Only used if --autoplay_delay was given. */
+ struct timeval autoplay_barrier;
+ /** Used for afs-server communication. */
+ int afs_socket;
+ /** The current state of \a afs_socket. */
+ enum afs_socket_status afsss;
+ /** The memory mapped audio file. */
+ char *map;
+ /** Used by the scheduler. */
+ struct task task;
+ /** Pointer to the header of the mapped audio file. */
+ char *header_buf;
+ /** Length of the audio file header. */
+ size_t header_len;
+ /** Time between audio file headers are sent. */
+ struct timeval header_interval;
+};
+
+/**
+ * The list of currently connected fec clients.
+ *
+ * Senders may use \ref vss_add_fec_client() to add entries to the list.
+ */
+static struct list_head fec_client_list;
+
+/**
+ * Data associated with one FEC group.
+ *
+ * A FEC group consists of a fixed number of slices and this number is given by
+ * the \a slices_per_group parameter of struct \ref fec_client_parms. Each FEC
+ * group contains a number of chunks of the current audio file.
+ *
+ * FEC slices directly correspond to the data packages sent by the paraslash
+ * senders that use FEC. Each slice is identified by its group number and its
+ * number within the group. All slices have the same size, but the last slice
+ * of the group may not be filled entirely.
+ */
+struct fec_group {
+ /** The number of the FEC group. */
+ uint32_t num;
+ /** Number of bytes in this group. */
+ uint32_t bytes;
+ /** The first chunk of the current audio file belonging to the group. */
+ uint32_t first_chunk;
+ /** The number of chunks contained in this group. */
+ uint32_t num_chunks;
+ /** When the first chunk was sent. */
+ struct timeval start;
+ /** The duration of the full group. */
+ struct timeval duration;
+ /** The group duration divided by the number of slices. */
+ struct timeval slice_duration;
+ /** Group contains the audio file header that occupies that many slices. */
+ uint8_t num_header_slices;
+ /** Number of bytes per slice for this group. */
+ uint16_t slice_bytes;
+};
+
+enum fec_client_state {
+ FEC_STATE_NONE = 0, /**< not initialized and not enabled */
+ FEC_STATE_DISABLED, /**< temporarily disabled */
+ FEC_STATE_READY_TO_RUN /**< initialized and enabled */
+};
+
+/**
+ * Describes one connected FEC client.
+ */
+struct fec_client {
+ /** Current state of the client */
+ enum fec_client_state state;
+ /** The connected sender client (transport layer). */
+ struct sender_client *sc;
+ /** Parameters requested by the client. */
+ struct fec_client_parms *fcp;
+ /** Used by the core FEC code. */
+ struct fec_parms *parms;
+ /** The position of this client in the fec client list. */
+ struct list_head node;
+ /** When the first slice for this client was sent. */
+ struct timeval stream_start;
+ /** The first chunk sent to this FEC client. */
+ int first_stream_chunk;
+ /** Describes the current group. */
+ struct fec_group group;
+ /** The current slice. */
+ uint8_t current_slice_num;
+ /** The data to be FEC-encoded (point to a region within the mapped audio file). */
+ const unsigned char **src_data;
+ /** Last time an audio header was sent. */
+ struct timeval next_header_time;
+ /** Used for the last source pointer of an audio file. */
+ unsigned char *extra_src_buf;
+ /** Needed for the last slice of the audio file header. */
+ unsigned char *extra_header_buf;
+ /** Extra slices needed to store largest chunk + header. */
+ int num_extra_slices;
+ /** Contains the FEC-encoded data. */
+ unsigned char *enc_buf;
+ /** Maximal packet size. */
+ int mps;
+};
+
+/**
+ * Get the chunk time of the current audio file.
+ *
+ * \return A pointer to a struct containing the chunk time, or NULL,
+ * if currently no audio file is selected.
+ */
+struct timeval *vss_chunk_time(void)
+{
+ if (mmd->afd.afhi.chunk_tv.tv_sec == 0 &&
+ mmd->afd.afhi.chunk_tv.tv_usec == 0)
+ return NULL;
+ return &mmd->afd.afhi.chunk_tv;
+}
+
+/**
+ * Write a fec header to a buffer.
+ *
+ * \param buf The buffer to write to.
+ * \param h The fec header to write.
+ */
+static void write_fec_header(struct fec_client *fc, struct vss_task *vsst)
+{
+ char *buf = (char *)fc->enc_buf;
+ struct fec_group *g = &fc->group;
+ struct fec_client_parms *p = fc->fcp;
+
+ write_u32(buf, FEC_MAGIC);
+
+ write_u8(buf + 4, p->slices_per_group + fc->num_extra_slices);
+ write_u8(buf + 5, p->data_slices_per_group + fc->num_extra_slices);
+ write_u32(buf + 6, g->num_header_slices? vsst->header_len : 0);
+
+ write_u32(buf + 10, g->num);
+ write_u32(buf + 14, g->bytes);
+
+ write_u8(buf + 18, fc->current_slice_num);
+ write_u8(buf + 19, 0); /* unused */
+ write_u16(buf + 20, g->slice_bytes);
+ write_u8(buf + 22, g->first_chunk? 0 : 1);
+ write_u8(buf + 23, vsst->header_len? 1 : 0);
+ memset(buf + 24, 0, 8);
+}
+
+static bool need_audio_header(struct fec_client *fc, struct vss_task *vsst)
+{
+ if (!mmd->current_chunk) {
+ tv_add(now, &vsst->header_interval, &fc->next_header_time);
+ return false;
+ }
+ if (!vsst->header_buf)
+ return false;
+ if (vsst->header_len == 0)
+ return false;
+ if (fc->group.num > 0) {
+ if (!fc->fcp->need_periodic_header)
+ return false;
+ if (tv_diff(&fc->next_header_time, now, NULL) > 0)
+ return false;
+ }
+ tv_add(now, &vsst->header_interval, &fc->next_header_time);
+ return true;
+}
+
+static bool need_data_slices(struct fec_client *fc, struct vss_task *vsst)
+{
+ if (fc->group.num > 0)
+ return true;
+ if (!vsst->header_buf)
+ return true;
+ if (vsst->header_len == 0)
+ return true;
+ if (fc->fcp->need_periodic_header)
+ return true;
+ return false;
+}
+
+static int num_slices(long unsigned bytes, int max_payload, int rs)
+{
+ int ret;
+
+ assert(max_payload > 0);
+ assert(rs > 0);
+ ret = DIV_ROUND_UP(bytes, max_payload);
+ if (ret + rs > 255)
+ return -E_BAD_CT;
+ return ret;
+}
+
+/* set group start and group duration */
+static void set_group_timing(struct fec_client *fc, struct vss_task *vsst)
+{
+ struct fec_group *g = &fc->group;
+ struct timeval *chunk_tv = vss_chunk_time();
+
+ if (!need_data_slices(fc, vsst))
+ ms2tv(200, &g->duration);
+ else
+ tv_scale(g->num_chunks, chunk_tv, &g->duration);
+ tv_divide(fc->fcp->slices_per_group + fc->num_extra_slices,
+ &g->duration, &g->slice_duration);
+ PARA_DEBUG_LOG("durations (group/chunk/slice): %lu/%lu/%lu\n",
+ tv2ms(&g->duration), tv2ms(chunk_tv), tv2ms(&g->slice_duration));
+}
+
+static int initialize_fec_client(struct fec_client *fc, struct vss_task *vsst)
+{
+ int k, n, ret;
+ int hs, ds, rs; /* header/data/redundant slices */
+ struct fec_client_parms *fcp = fc->fcp;
+
+ /* set mps */
+ if (fcp->init_fec) {
+ /*
+ * Set the maximum slice size to the Maximum Packet Size if the
+ * transport protocol allows to determine this value. The user
+ * can specify a slice size up to this value.
+ */
+ ret = fcp->init_fec(fc->sc);
+ if (ret < 0)
+ return ret;
+ fc->mps = ret;
+ } else
+ fc->mps = generic_max_transport_msg_size(fc->sc->fd);
+ if (fc->mps <= FEC_HEADER_SIZE)
+ return -ERRNO_TO_PARA_ERROR(EINVAL);
+
+ rs = fc->fcp->slices_per_group - fc->fcp->data_slices_per_group;
+ ret = num_slices(vsst->header_len, fc->mps - FEC_HEADER_SIZE, rs);
+ if (ret < 0)
+ return ret;
+ hs = ret;
+ ret = num_slices(mmd->afd.max_chunk_size, fc->mps - FEC_HEADER_SIZE, rs);
+ if (ret < 0)
+ return ret;
+ ds = ret;
+ if (fc->fcp->need_periodic_header)
+ k = hs + ds;
+ else
+ k = PARA_MAX(hs, ds);
+ if (k < fc->fcp->data_slices_per_group)
+ k = fc->fcp->data_slices_per_group;
+ fc->num_extra_slices = k - fc->fcp->data_slices_per_group;
+ n = k + rs;
+ fec_free(fc->parms);
+ ret = fec_new(k, n, &fc->parms);
+ if (ret < 0)
+ return ret;
+ PARA_INFO_LOG("mps: %d, k: %d, n: %d, extra slices: %d\n",
+ fc->mps, k, n, fc->num_extra_slices);
+ fc->src_data = para_realloc(fc->src_data, k * sizeof(char *));
+ fc->enc_buf = para_realloc(fc->enc_buf, fc->mps);
+ fc->extra_src_buf = para_realloc(fc->extra_src_buf, fc->mps);
+ fc->extra_header_buf = para_realloc(fc->extra_header_buf, fc->mps);
+
+ fc->state = FEC_STATE_READY_TO_RUN;
+ fc->next_header_time.tv_sec = 0;
+ fc->stream_start = *now;
+ fc->first_stream_chunk = mmd->current_chunk;
+ return 1;
+}
+
+static void vss_get_chunk(int chunk_num, struct vss_task *vsst,
+ char **buf, size_t *sz)
+{
+ /*
+ * Chunk zero is special for header streams: It is the first portion of
+ * the audio file which consists of the audio file header. It may be
+ * arbitrary large due to embedded meta data. Audio format handlers may
+ * replace the header by a stripped one with meta data omitted which is
+ * of bounded size. We always use the stripped header for streaming
+ * rather than the unmodified header (chunk zero).
+ */
+ if (chunk_num == 0 && vsst->header_len > 0) {
+ *buf = vsst->header_buf; /* stripped header */
+ *sz = vsst->header_len;
+ return;
+ }
+ afh_get_chunk(chunk_num, &mmd->afd.afhi, vsst->map, (const char **)buf,
+ sz);
+}
+
+static void compute_group_size(struct vss_task *vsst, struct fec_group *g,
+ int max_bytes)
+{
+ int i, max_chunks = PARA_MAX(1LU, 150 / tv2ms(vss_chunk_time()));
+
+ g->num_chunks = 0;
+ g->bytes = 0;
+ /*
+ * Include chunks into the group until the group duration is at least
+ * 150ms. For ogg and wma, a single chunk's duration (ogg page/wma
+ * super frame) is already larger than 150ms, so a FEC group consists
+ * of exactly one chunk for these audio formats.
+ */
+ for (i = 0;; i++) {
+ char *buf;
+ size_t len;
+ int chunk_num = g->first_chunk + i;
+
+ if (g->bytes > 0 && i >= max_chunks) /* duration limit */
+ break;
+ if (chunk_num >= mmd->afd.afhi.chunks_total) /* eof */
+ break;
+ vss_get_chunk(chunk_num, vsst, &buf, &len);
+ if (g->bytes + len > max_bytes)
+ break;
+ /* Include this chunk */
+ g->bytes += len;
+ g->num_chunks++;
+ }
+ assert(g->num_chunks);
+}
+
+/*
+ * Compute the slice size of the next group.
+ *
+ * The FEC parameters n and k are fixed but the slice size varies per
+ * FEC group. We'd like to choose slices as small as possible to avoid
+ * unnecessary FEC calculations but large enough to guarantee that the
+ * k data slices suffice to encode the header (if needed) and the data
+ * chunk(s).
+ *
+ * Once we know the payload of the next group, we define the number s
+ * of bytes per slice for this group by
+ *
+ * s = ceil(payload / k)
+ *
+ * However, for header streams, computing s is more complicated since no
+ * overlapping of header and data slices is possible. Hence we have k >=
+ * 2 and s must satisfy
+ *
+ * (*) ceil(h / s) + ceil(d / s) <= k
+ *
+ * where h and d are payload of the header and the data chunk(s)
+ * respectively. In general there is no value for s such that (*)
+ * becomes an equality, for example if h = 4000, d = 5000 and k = 10.
+ *
+ * We use the following approach for computing a suitable value for s:
+ *
+ * Let
+ * k1 := ceil(k * min(h, d) / (h + d)),
+ * k2 := k - k1.
+ *
+ * Note that k >= 2 implies k1 > 0 and k2 > 0, so
+ *
+ * s := max(ceil(min(h, d) / k1), ceil(max(h, d) / k2))
+ *
+ * is well-defined. Inequality (*) holds for this value of s since k1
+ * slices suffice to store min(h, d) while k2 slices suffice to store
+ * max(h, d), i.e. the first addent of (*) is bounded by k1 and the
+ * second by k2.
+ *
+ * For the above example we obtain
+ *
+ * k1 = ceil(10 * 4000 / 9000) = 5, k2 = 5,
+ * s = max(4000 / 5, 5000 / 5) = 1000,
+ *
+ * which is optimal since a slice size of 999 bytes would already require
+ * 11 slices.
+ */
+static int compute_slice_size(struct fec_client *fc, struct vss_task *vsst)
+{
+ struct fec_group *g = &fc->group;
+ int k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
+ int n = fc->fcp->slices_per_group + fc->num_extra_slices;
+ int ret, k1, k2, h, d, min, max, sum;
+ int max_slice_bytes = fc->mps - FEC_HEADER_SIZE;
+ int max_group_bytes;
+
+ if (!need_audio_header(fc, vsst)) {
+ max_group_bytes = k * max_slice_bytes;
+ g->num_header_slices = 0;
+ compute_group_size(vsst, g, max_group_bytes);
+ g->slice_bytes = DIV_ROUND_UP(g->bytes, k);
+ if (g->slice_bytes == 0)
+ g->slice_bytes = 1;
+ return 1;
+ }
+ if (!need_data_slices(fc, vsst)) {
+ g->bytes = 0;
+ g->num_chunks = 0;
+ g->slice_bytes = DIV_ROUND_UP(vsst->header_len, k);
+ g->num_header_slices = k;
+ return 1;
+ }
+ h = vsst->header_len;
+ max_group_bytes = (k - num_slices(h, max_slice_bytes, n - k))
+ * max_slice_bytes;
+ compute_group_size(vsst, g, max_group_bytes);
+ d = g->bytes;
+ if (d == 0) {
+ g->slice_bytes = DIV_ROUND_UP(h, k);
+ ret = num_slices(vsst->header_len, g->slice_bytes, n - k);
+ if (ret < 0)
+ return ret;
+ g->num_header_slices = ret;
+ return 1;
+ }
+ min = PARA_MIN(h, d);
+ max = PARA_MAX(h, d);
+ sum = h + d;
+ k1 = DIV_ROUND_UP(k * min, sum);
+ k2 = k - k1;
+ assert(k1 > 0);
+ assert(k2 > 0);
+
+ g->slice_bytes = PARA_MAX(DIV_ROUND_UP(min, k1), DIV_ROUND_UP(max, k2));
+ /*
+ * This value of s := g->slice_bytes satisfies inequality (*) above,
+ * but it might be larger than max_slice_bytes. However, we know that
+ * max_slice_bytes are sufficient to store header and data, so:
+ */
+ g->slice_bytes = PARA_MIN((int)g->slice_bytes, max_slice_bytes);