+/** 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;
+ /** 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 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;
+};
+
+/**
+ * Describes one connected FEC client.
+ */
+struct fec_client {
+ /** If negative, this client is temporarily disabled. */
+ int error;
+ /** 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;
+ /** Extra slices needed to store largest chunk + header. */
+ int num_extra_slices;
+ /** Contains the FEC-encoded data. */
+ unsigned char *enc_buf;
+};
+
+/**
+ * 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_u16(buf + 20, p->max_slice_bytes - FEC_HEADER_SIZE);
+ write_u8(buf + 22, g->first_chunk? 0 : 1);
+ write_u8(buf + 23, vsst->header_len? 1 : 0);
+ memset(buf + 24, 0, 7);
+}
+
+static int 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 0;
+ }
+ if (!vsst->header_buf)
+ return 0;
+ if (!vsst->header_len)
+ return 0;
+ if (fc->group.num && tv_diff(&fc->next_header_time, now, NULL) > 0)
+ return 0;
+ tv_add(now, &vsst->header_interval, &fc->next_header_time);
+ return 1;
+}
+
+static int num_slices(long unsigned bytes, struct fec_client *fc, uint8_t *result)
+{
+ unsigned long m = fc->fcp->max_slice_bytes - FEC_HEADER_SIZE;
+ unsigned rv, redundant_slices = fc->fcp->slices_per_group
+ - fc->fcp->data_slices_per_group;
+
+ if (!m)
+ return -E_BAD_CT;
+ rv = (bytes + m - 1) / m;
+ if (rv + redundant_slices > 255)
+ return -E_BAD_CT;
+ *result = rv;
+ return 1;
+}
+
+static void set_slice_duration(struct fec_client *fc, struct fec_group *g)
+{
+ struct timeval group_duration, *chunk_tv = vss_chunk_time();
+
+ tv_scale(g->num_chunks, chunk_tv, &group_duration);
+ tv_divide(fc->fcp->slices_per_group + fc->num_extra_slices,
+ &group_duration, &g->slice_duration);
+ PARA_DEBUG_LOG("durations (group/chunk/slice): %lu/%lu/%lu\n",
+ tv2ms(&group_duration), tv2ms(chunk_tv), tv2ms(&g->slice_duration));
+}