+/** 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. */
+ const char *header_buf;
+ /** Length of the audio file header. */
+ size_t header_len;
+};
+
+/**
+ * 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;
+
+/**
+ * Describes one slice of a FEC group.
+ *
+ * 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_slice {
+ /** The slice number within the FEC group. */
+ uint8_t num;
+ /** The number of used bytes in this slice. */
+ uint16_t bytes;
+};
+
+/**
+ * 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.
+ */
+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;
+ /** The time needed to play all chunks of the group. */
+ struct timeval duration;
+ /** When the first chunk was sent. */
+ struct timeval start;
+ /** \a The group duration divided by \a slices_per_group. */
+ struct timeval slice_duration;
+};
+
+/**
+ * Describes one connected FEC client.
+ */
+struct fec_client {
+ /** 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;
+ /** Describes the current slice. */
+ struct fec_slice slice;
+ /** The data to be FEC-encoded (point to a region within the mapped audio file). */
+ const unsigned char **src_data;
+ /** Used for the last source pointer of the last group. */
+ unsigned char *extra_src_buf;
+ /** The size of the buffer for the extra source pointer. */
+ size_t extra_src_buf_size;
+ /** Contains FEC-encoded data. */
+ unsigned char *enc_buf;
+ /** Size of \a enc_buf. */
+ size_t enc_buf_size;
+};
+
+/**
+ * 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)
+{
+ char *buf = (char *)fc->enc_buf;
+
+ write_u32(buf, FEC_MAGIC);
+
+ write_u8(buf + 4, fc->fcp->slices_per_group);
+ write_u8(buf + 5, fc->fcp->data_slices_per_group);
+ write_u32(buf + 6, (uint32_t)0); /* audio header len */
+
+ write_u32(buf + 10, fc->group.num);
+ write_u32(buf + 14, fc->group.bytes);
+
+ write_u8(buf + 18, fc->slice.num);
+ write_u16(buf + 20, fc->slice.bytes);
+ memset(buf + 22, 0, 11);
+}
+
+static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
+{
+ uint32_t max_group_size, last_payload_size;
+ int i, k = fc->fcp->data_slices_per_group;
+ size_t len;
+ const char *start_buf;
+ struct timeval tmp, *chunk_tv = vss_chunk_time();
+
+ assert(chunk_tv);
+ if (fc->first_stream_chunk < 0) {
+ fc->stream_start = *now;
+ fc->first_stream_chunk = mmd->current_chunk;
+ fc->group.first_chunk = mmd->current_chunk;
+ fc->group.num = 0;
+ } else {
+ fc->group.first_chunk += fc->group.num_chunks;
+ fc->group.num++;
+ }
+ if (fc->group.first_chunk >= mmd->afd.afhi.chunks_total)
+ return 0;
+ max_group_size = (fc->fcp->max_slice_bytes - FEC_HEADER_SIZE) * k;
+ afh_get_chunk(fc->group.first_chunk, &mmd->afd.afhi, vsst->map,
+ &start_buf, &len);
+ for (i = fc->group.first_chunk, fc->group.bytes = 0;
+ i < mmd->afd.afhi.chunks_total; i++) {
+ const char *buf;
+
+ afh_get_chunk(i, &mmd->afd.afhi, vsst->map, &buf, &len);
+ if (fc->group.bytes + len > max_group_size)
+ break;
+ fc->group.bytes += len;
+ }
+ fc->group.num_chunks = i - fc->group.first_chunk;
+ fc->slice.num = 0;
+ fc->slice.bytes = ROUND_UP(fc->group.bytes, k) / k;
+ /* FIXME: Avoid division by zero in a better way */
+ if (!fc->slice.bytes)
+ return 0;
+
+ /* The last slice will not be fully used */
+ last_payload_size = fc->group.bytes % fc->slice.bytes;
+ if (!last_payload_size)
+ last_payload_size = fc->slice.bytes;
+
+ tv_scale(fc->group.first_chunk - fc->first_stream_chunk, chunk_tv,
+ &tmp);
+ tv_add(&fc->stream_start, &tmp, &fc->group.start);
+ if (fc->group.num) /* quick hack to avoid buffer underruns */
+ fc->group.start.tv_sec--;
+ tv_scale(fc->group.num_chunks, chunk_tv, &fc->group.duration);
+ tv_divide(fc->fcp->slices_per_group, &fc->group.duration,
+ &fc->group.slice_duration);
+
+ for (i = 0; i < k; i++)
+ fc->src_data[i] = (const unsigned char *)start_buf
+ + i * fc->slice.bytes;
+
+ if (start_buf + k * fc->slice.bytes > vsst->map + mmd->size) {
+ /* can not use last slice as it goes beyond the map */
+ if (fc->extra_src_buf_size < fc->slice.bytes) {
+ fc->extra_src_buf = para_realloc(fc->extra_src_buf, fc->slice.bytes);
+ fc->extra_src_buf_size = fc->slice.bytes;
+ }
+ memcpy(fc->extra_src_buf, start_buf + (k - 1) * fc->slice.bytes,
+ last_payload_size);
+ memset(fc->extra_src_buf + last_payload_size, 0,
+ fc->slice.bytes - last_payload_size);
+ fc->src_data[k - 1] = fc->extra_src_buf;
+ }
+ if (fc->enc_buf_size < fc->slice.bytes + FEC_HEADER_SIZE) {
+ fc->enc_buf_size = fc->slice.bytes + FEC_HEADER_SIZE;
+ fc->enc_buf = para_realloc(fc->enc_buf, fc->enc_buf_size);
+ }
+ PARA_INFO_LOG("FEC group %d: %d chunks (%d - %d), duration: %lums\n",
+ fc->group.num, fc->group.num_chunks, fc->group.first_chunk,
+ fc->group.first_chunk + fc->group.num_chunks - 1,
+ tv2ms(&fc->group.duration));
+ return 1;
+}
+
+static int compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
+{
+ if (fc->first_stream_chunk < 0 || fc->slice.num
+ == fc->fcp->slices_per_group) {
+ if (!setup_next_fec_group(fc, vsst))
+ return 0;
+ }
+ write_fec_header(fc);
+ fec_encode(fc->parms, fc->src_data, fc->enc_buf + FEC_HEADER_SIZE,
+ fc->slice.num, fc->slice.bytes);
+ return 1;
+}
+
+/**
+ * Return a buffer that marks the end of the stream.
+ *
+ * \param buf Result pointer.
+ * \return The length of the eof buffer.
+ *
+ * This is used for (multicast) udp streaming where closing the socket on the
+ * sender might not give rise to an eof condition at the peer.
+ */
+size_t vss_get_fec_eof_packet(const char **buf)
+{
+ static const char fec_eof_packet[FEC_HEADER_SIZE] = FEC_EOF_PACKET;
+ *buf = fec_eof_packet;
+ return FEC_HEADER_SIZE;
+}
+
+/**
+ * Add one entry to the list of active fec clients.
+ *
+ * \param fcp Describes the fec parameters to be used for this client.
+ * \param result An opaque pointer that must be used by remove the client later.
+ *
+ * \return Standard.
+ */
+int vss_add_fec_client(struct fec_client_parms *fcp, struct fec_client **result)
+{
+ int ret;
+ struct fec_client *fc;
+
+ if (fcp->max_slice_bytes < FEC_HEADER_SIZE + fcp->data_slices_per_group)
+ return -ERRNO_TO_PARA_ERROR(EINVAL);
+ fc = para_calloc(sizeof(*fc));
+ fc->fcp = fcp;
+ ret = fec_new(fcp->data_slices_per_group, fcp->slices_per_group,
+ &fc->parms);
+ if (ret < 0)
+ goto err;
+ fc->first_stream_chunk = -1; /* stream not yet started */
+ fc->src_data = para_malloc(fc->fcp->slices_per_group * sizeof(char *));
+ para_list_add(&fc->node, &fec_client_list);
+ *result = fc;
+ return 1;
+err:
+ fec_free(fc->parms);
+ free(fc);
+ *result = NULL;
+ return ret;
+}
+
+/**
+ * Remove one entry from the list of active fec clients.
+ *
+ * \param fc The client to be removed.
+ */
+void vss_del_fec_client(struct fec_client *fc)
+{
+ list_del(&fc->node);
+ free(fc->src_data);
+ free(fc->enc_buf);
+ free(fc->extra_src_buf);
+ fec_free(fc->parms);
+ free(fc);
+}
+
+/*
+ * Compute if/when next slice is due. If it isn't due yet and \a diff is
+ * not \p Null, compute the time difference next - now, where
+ *
+ * next = stream_start + (first_group_chunk - first_stream_chunk)
+ * * chunk_time + slice_num * slice_time
+ */
+static int next_slice_is_due(struct fec_client *fc, struct timeval *diff)
+{
+ struct timeval tmp, next;
+ int ret;
+
+ if (fc->first_stream_chunk < 0)
+ return 1;
+ tv_scale(fc->slice.num, &fc->group.slice_duration, &tmp);
+ tv_add(&tmp, &fc->group.start, &next);
+ ret = tv_diff(&next, now, diff);
+ return ret < 0? 1 : 0;
+}
+
+static void compute_slice_timeout(struct timeval *timeout)
+{
+ struct fec_client *fc;