+/** 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;
+}
+
+static void setup_fec_group(struct fec_client *fc, struct vss_task *vsst)
+{
+ uint32_t num_bytes = 0, chunk_num, max_group_size, last_payload_size;
+ int i, k = fc->fcp->data_slices_per_group;
+ const char *start_buf = NULL;
+ struct timeval tmp, *chunk_tv = vss_chunk_time();
+
+ assert(chunk_tv);
+ max_group_size = (fc->fcp->max_slice_bytes - FEC_HEADER_SIZE) * k;
+ chunk_num = fc->group.first_chunk;
+ for (;;) {
+ const char *buf;
+ size_t len;
+
+ if (chunk_num >= mmd->afd.afhi.chunks_total)
+ break;
+ afh_get_chunk(chunk_num, &mmd->afd.afhi, vsst->map, &buf, &len);
+ if (!start_buf)
+ start_buf = buf;
+ if (num_bytes + len > max_group_size)
+ break;
+ chunk_num++;
+ num_bytes += len;
+ }
+ assert(start_buf);
+ fc->group.num_chunks = chunk_num - fc->group.first_chunk;
+ fc->group.num++;
+ fc->group.bytes = num_bytes;
+ fc->slice.num = 0;
+ fc->slice.bytes = ROUND_UP(num_bytes, k) / k;
+
+ /* The last slice will not be fully used */
+ last_payload_size = num_bytes % fc->slice.bytes;
+ if (!last_payload_size)
+ last_payload_size = fc->slice.bytes;
+
+ tv_scale(fc->group.num_chunks, chunk_tv, &fc->group.duration);
+ tv_scale(fc->group.first_chunk - fc->first_stream_chunk, chunk_tv,
+ &tmp);
+ tv_add(&fc->stream_start, &tmp, &fc->group.start);
+ 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);
+ 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;
+ }
+
+}
+
+/**
+ * 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);