+/** 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;
+};
+
+static struct list_head fec_client_list;
+
+struct fec_slice {
+ uint8_t num;
+ uint16_t bytes;
+};
+
+struct fec_group {
+ uint32_t num;
+ uint32_t bytes;
+ uint32_t first_chunk;
+ uint32_t num_chunks;
+ struct timeval duration;
+ struct timeval start;
+ struct timeval slice_duration;
+};
+
+struct fec_client {
+ struct fec_client_parms *fcp;
+ struct fec_parms *parms;
+ struct list_head node;
+ struct timeval stream_start;
+ int first_stream_chunk;
+ struct fec_group group;
+ struct fec_slice slice;
+ const unsigned char **src_data;
+ unsigned char *extra_src_buf;
+ size_t extra_src_buf_size;
+ unsigned char *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);
+
+ 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);
+}
+
+/**
+ * Return a buffer that marks the end of the stream.
+ *
+ * \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] =
+ "\xec\x0d\xcc\xfe\0\0\0\0"
+ "\0\0\0\0\0\0\0\0"
+ "\0\0\0\0\0\0\0\0"
+ "\0\0\0\0\0\0\0\0";
+ *buf = fec_eof_packet;
+ return FEC_HEADER_SIZE;
+}
+
+static void compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
+{
+ 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;
+ setup_fec_group(fc, vsst);
+ } else if (fc->slice.num == fc->fcp->slices_per_group) {
+ fc->group.first_chunk += fc->group.num_chunks;
+ setup_fec_group(fc, vsst);