Add documentation to struct rc4_context.
[paraslash.git] / vss.c
diff --git a/vss.c b/vss.c
index ab5cd1b..21f4cb4 100644 (file)
--- a/vss.c
+++ b/vss.c
 /*
- * Copyright (C) 1997-2007 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 1997-2009 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
 
-/** \file vss.c the virtual streaming system
+/** \file vss.c The virtual streaming system.
  *
  * This contains the audio streaming code of para_server which is independent
  * of the current audio format, audio file selector and of the activated
  * senders.
  */
 
-#include <sys/mman.h> /* mmap */
-#include <sys/time.h> /* gettimeofday */
-#include <sys/types.h>
+#include <regex.h>
 #include <dirent.h>
+#include <osl.h>
 
 #include "para.h"
 #include "error.h"
+#include "portable_io.h"
+#include "fec.h"
 #include "string.h"
 #include "afh.h"
 #include "afs.h"
 #include "server.h"
 #include "net.h"
 #include "server.cmdline.h"
-#include "afs_common.h"
+#include "list.h"
 #include "vss.h"
 #include "send.h"
 #include "ipc.h"
 #include "fd.h"
+#include "sched.h"
 
-extern const char *status_item_list[];
+extern struct misc_meta_data *mmd;
 
-static struct timeval announce_tv;
-static struct timeval data_send_barrier;
-static struct timeval eof_barrier;
-static struct timeval autoplay_barrier;
+extern void dccp_send_init(struct sender *);
+extern void http_send_init(struct sender *);
+extern void udp_send_init(struct sender *);
+
+/** 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,
+       }
+};
 
-extern struct misc_meta_data *mmd;
-extern struct sender senders[];
+/** 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 int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
+{
+       int ret, i, k, data_slices;
+       size_t len;
+       const char *buf, *start_buf;
+       struct timeval tmp, *chunk_tv = vss_chunk_time();
+       struct fec_group *g = &fc->group;
+       unsigned slice_bytes = fc->fcp->max_slice_bytes - FEC_HEADER_SIZE;
+       uint32_t max_data_size;
+
+       assert(chunk_tv);
+       k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
+       if (fc->first_stream_chunk < 0) {
+               uint32_t largest = afh_get_largest_chunk_size(&mmd->afd.afhi)
+                       + vsst->header_len;
+               uint8_t needed, want;
+
+               ret = num_slices(largest, fc, &needed);
+               if (ret < 0)
+                       return ret;
+               if (needed > fc->fcp->data_slices_per_group)
+                       PARA_WARNING_LOG("fec parms insufficient for this audio file\n");
+               want = PARA_MAX(needed, fc->fcp->data_slices_per_group);
+               if (want != k) {
+                       fec_free(fc->parms);
+                       fc->src_data = para_realloc(fc->src_data, want * sizeof(char *));
+                       ret = fec_new(want, want + fc->fcp->slices_per_group
+                               - fc->fcp->data_slices_per_group, &fc->parms);
+                       if (ret < 0)
+                               return ret;
+                       k = want;
+                       fc->num_extra_slices = 0;
+                       if (k > fc->fcp->data_slices_per_group) {
+                               fc->num_extra_slices = k - fc->fcp->data_slices_per_group;
+                               PARA_NOTICE_LOG("using %d extra slices\n",
+                                       fc->num_extra_slices);
+                       }
+               }
+               fc->stream_start = *now;
+               fc->first_stream_chunk = mmd->current_chunk;
+               g->first_chunk = mmd->current_chunk;
+               g->num = 0;
+       } else {
+               g->first_chunk += g->num_chunks;
+               g->num++;
+       }
+       if (g->first_chunk >= mmd->afd.afhi.chunks_total)
+               return 0;
+       if (need_audio_header(fc, vsst)) {
+               ret = num_slices(vsst->header_len, fc, &g->num_header_slices);
+               if (ret < 0)
+                       return ret;
+       } else
+               g->num_header_slices = 0;
+       afh_get_chunk(g->first_chunk, &mmd->afd.afhi, vsst->map, &start_buf,
+               &len);
+       data_slices = k - g->num_header_slices;
+       assert(data_slices);
+       max_data_size = slice_bytes * data_slices;
+       g->bytes = 0;
+       for (i = g->first_chunk; i < mmd->afd.afhi.chunks_total; i++) {
+               afh_get_chunk(i, &mmd->afd.afhi, vsst->map, &buf, &len);
+               if (g->bytes + len > max_data_size)
+                       break;
+               g->bytes += len;
+       }
+       g->num_chunks = i - g->first_chunk;
+       assert(g->num_chunks);
+       fc->current_slice_num = 0;
+
+       /* setup header slices */
+       buf = vsst->header_buf;
+       for (i = 0; i < g->num_header_slices; i++) {
+               fc->src_data[i] = (const unsigned char *)buf;
+               buf += slice_bytes;
+       }
+
+       /* setup data slices */
+       buf = start_buf;
+       for (i = g->num_header_slices; i < k; i++) {
+               if (buf + slice_bytes > vsst->map + mmd->size)
+                       /*
+                        * Can not use the memory mapped audio file for this
+                        * slice as it goes beyond the map. This slice will not
+                        * be fully used.
+                        */
+                       break;
+               fc->src_data[i] = (const unsigned char *)buf;
+               buf += slice_bytes;
+       }
+       if (i < k) {
+               uint32_t payload_size = vsst->map + mmd->size - buf;
+               memcpy(fc->extra_src_buf, buf, payload_size);
+               fc->src_data[i] = fc->extra_src_buf;
+               i++;
+               /* use arbitrary data for all remaining slices */
+               buf = vsst->map;
+               for (; i < k; i++)
+                       fc->src_data[i] = (const unsigned char *)buf;
+       }
+
+       /* setup group timing */
+       tv_scale(g->first_chunk - fc->first_stream_chunk, chunk_tv, &tmp);
+       tv_add(&fc->stream_start, &tmp, &g->start);
+       if (g->num) /* quick hack to avoid buffer underruns */
+               g->start.tv_sec--;
+       tv_scale(g->num_chunks, chunk_tv, &tmp); /* group duration */
+       tv_divide(fc->fcp->slices_per_group + fc->num_extra_slices,
+               &tmp, &g->slice_duration);
+
+       PARA_DEBUG_LOG("FEC group %d: %d chunks (%d - %d), %d header slices, %d data slices\n",
+               g->num, g->num_chunks, g->first_chunk,
+               g->first_chunk + g->num_chunks - 1,
+               g->num_header_slices, data_slices
+       );
+       PARA_DEBUG_LOG("durations (group/chunk/slice): %lu/%lu/%lu\n",
+               tv2ms(&tmp), tv2ms(chunk_tv), tv2ms(&g->slice_duration));
+       return 1;
+}
+
+static int compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
+{
+       assert(fc->error >= 0);
+       if (fc->first_stream_chunk < 0 || fc->current_slice_num
+                       == fc->fcp->slices_per_group + fc->num_extra_slices) {
+               int ret = setup_next_fec_group(fc, vsst);
+               if (ret == 0)
+                       return 0;
+               if (ret < 0) {
+                       PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+                       PARA_ERROR_LOG("FEC client temporarily disabled\n");
+                       fc->error = ret;
+                       return fc->error;
+               }
+       }
+       write_fec_header(fc, vsst);
+       fec_encode(fc->parms, fc->src_data, fc->enc_buf + FEC_HEADER_SIZE,
+               fc->current_slice_num,
+               fc->fcp->max_slice_bytes - FEC_HEADER_SIZE);
+       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 *));
+       fc->enc_buf = para_calloc(fc->fcp->max_slice_bytes);
+       fc->num_extra_slices = 0;
+       fc->extra_src_buf = para_calloc(fc->fcp->max_slice_bytes);
+       fc->next_header_time.tv_sec = 0;
+       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->current_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;
+
+       assert(vss_playing());
+       list_for_each_entry(fc, &fec_client_list, node) {
+               struct timeval diff;
+
+               if (fc->error < 0)
+                       continue;
+               if (next_slice_is_due(fc, &diff)) {
+                       timeout->tv_sec = 0;
+                       timeout->tv_usec = 0;
+                       return;
+               }
+               /* timeout = min(timeout, diff) */
+               if (tv_diff(&diff, timeout, NULL) < 0)
+                       *timeout = diff;
+       }
+}
 
-static char *map;
+static void set_eof_barrier(struct vss_task *vsst)
+{
+       struct fec_client *fc;
+       struct timeval timeout = {1, 0}, *chunk_tv = vss_chunk_time();
+
+       if (!chunk_tv)
+               goto out;
+       list_for_each_entry(fc, &fec_client_list, node) {
+               struct timeval group_duration;
+
+               if (fc->error < 0)
+                       continue;
+               tv_scale(fc->group.num_chunks, chunk_tv, &group_duration);
+               if (tv_diff(&timeout, &group_duration, NULL) < 0)
+                       timeout = group_duration;
+       }
+out:
+       tv_add(now, &timeout, &vsst->eof_barrier);
+}
 
 /**
- * check if vss status flag \a P (playing) is set
+ * Check if vss status flag \a P (playing) is set.
  *
- * \return greater than zero if playing, zero otherwise.
+ * \return Greater than zero if playing, zero otherwise.
  *
  */
 unsigned int vss_playing(void)
@@ -54,9 +517,9 @@ unsigned int vss_playing(void)
 }
 
 /**
- * check if \a N (next) status flag is set
+ * Check if the \a N (next) status flag is set.
  *
- * \return greater than zero if set, zero if not.
+ * \return Greater than zero if set, zero if not.
  *
  */
 unsigned int vss_next(void)
@@ -65,9 +528,9 @@ unsigned int vss_next(void)
 }
 
 /**
- * check if a reposition request is pending
+ * Check if a reposition request is pending.
  *
- * \return greater than zero if true, zero otherwise.
+ * \return Greater than zero if true, zero otherwise.
  *
  */
 unsigned int vss_repos(void)
@@ -76,9 +539,9 @@ unsigned int vss_repos(void)
 }
 
 /**
- * check if the vss is currently paused
+ * Check if the vss is currently paused.
  *
- * \return greater than zero if paused, zero otherwise.
+ * \return Greater than zero if paused, zero otherwise.
  *
  */
 unsigned int vss_paused(void)
@@ -88,40 +551,19 @@ unsigned int vss_paused(void)
 }
 
 /**
- * initialize the virtual streaming system
+ * Check if the vss is currently stopped.
+ *
+ * \return Greater than zero if paused, zero otherwise.
  *
- * Call the init functions of all supported audio format handlers and
- * initialize all supported senders.
  */
-void vss_init(void)
+unsigned int vss_stopped(void)
 {
-       int i;
-       char *hn = para_hostname(), *home = para_homedir();
-       long unsigned announce_time = conf.announce_time_arg > 0?
-                       conf.announce_time_arg : 300,
-               autoplay_delay = conf.autoplay_delay_arg > 0?
-                       conf.autoplay_delay_arg : 0;
-       ms2tv(announce_time, &announce_tv);
-       PARA_INFO_LOG("announce timeval: %lums\n", tv2ms(&announce_tv));
-       for (i = 0; senders[i].name; i++) {
-               PARA_NOTICE_LOG("initializing %s sender\n", senders[i].name);
-               senders[i].init(&senders[i]);
-       }
-       free(hn);
-       free(home);
-       if (conf.autoplay_given) {
-               struct timeval now, tmp;
-               mmd->vss_status_flags |= VSS_PLAYING;
-               mmd->new_vss_status_flags |= VSS_PLAYING;
-               gettimeofday(&now, NULL);
-               ms2tv(autoplay_delay, &tmp);
-               tv_add(&now, &tmp, &autoplay_barrier);
-       }
+       return (mmd->new_vss_status_flags & VSS_NEXT)
+               && !(mmd->new_vss_status_flags & VSS_PLAYING);
 }
 
-static int chk_barrier(const char *bname, const struct timeval *now,
-               const struct timeval *barrier, struct timeval *diff,
-               int print_log)
+static int chk_barrier(const char *bname, const struct timeval *barrier,
+               struct timeval *diff, int print_log)
 {
        long ms;
 
@@ -133,107 +575,70 @@ static int chk_barrier(const char *bname, const struct timeval *now,
        return -1;
 }
 
-static void vss_next_chunk_time(struct timeval *due)
-{
-       struct timeval tmp;
-
-       tv_scale(mmd->chunks_sent, &mmd->afi.chunk_tv, &tmp);
-       tv_add(&tmp, &mmd->stream_start, due);
-}
-
 /*
  * != NULL: timeout for next chunk
  * NULL: nothing to do
  */
-static struct timeval *vss_compute_timeout(void)
+static struct timeval *vss_compute_timeout(struct vss_task *vsst)
 {
        static struct timeval the_timeout;
-       struct timeval now, next_chunk;
+       struct timeval next_chunk;
 
-       if (vss_next() && mmd->audio_format >= 0) {
+       if (vss_next() && vsst->map) {
                /* only sleep a bit, nec*/
                the_timeout.tv_sec = 0;
                the_timeout.tv_usec = 100;
                return &the_timeout;
        }
-       gettimeofday(&now, NULL);
-       if (chk_barrier("autoplay_delay", &now, &autoplay_barrier,
+       if (chk_barrier("autoplay_delay", &vsst->autoplay_barrier,
                        &the_timeout, 1) < 0)
                return &the_timeout;
-       if (chk_barrier("eof", &now, &eof_barrier, &the_timeout, 1) < 0)
+       if (chk_barrier("eof", &vsst->eof_barrier, &the_timeout, 1) < 0)
                return &the_timeout;
-       if (chk_barrier("data send", &now, &data_send_barrier,
+       if (chk_barrier("data send", &vsst->data_send_barrier,
                        &the_timeout, 1) < 0)
                return &the_timeout;
-       if (mmd->audio_format < 0 || !vss_playing() || !map)
+       if (!vss_playing() || !vsst->map)
                return NULL;
-       vss_next_chunk_time(&next_chunk);
-       if (chk_barrier(audio_format_name(mmd->audio_format), &now, &next_chunk,
-                       &the_timeout, 0) < 0)
+       compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
+               &mmd->stream_start, &next_chunk);
+       if (chk_barrier("chunk", &next_chunk, &the_timeout, 0) >= 0) {
+               /* chunk is due or bof */
+               the_timeout.tv_sec = 0;
+               the_timeout.tv_usec = 0;
                return &the_timeout;
-       /* chunk is due or bof */
-       the_timeout.tv_sec = 0;
-       the_timeout.tv_usec = 0;
+       }
+       /* compute min of current timeout and next slice time */
+       compute_slice_timeout(&the_timeout);
        return &the_timeout;
 }
 
-static void vss_eof(void)
+static void vss_eof(struct vss_task *vsst)
 {
-       struct timeval now;
-       int i;
-       char *tmp;
 
-       PARA_NOTICE_LOG("EOF\n");
-       if (!map) {
-               for (i = 0; senders[i].name; i++)
-                       senders[i].shutdown_clients();
+       if (!vsst->map)
                return;
-       }
-       gettimeofday(&now, NULL);
-       tv_add(&mmd->afi.eof_tv, &now, &eof_barrier);
-       munmap(map, mmd->size);
-       map = NULL;
-       mmd->audio_format = -1;
+       if (mmd->new_vss_status_flags & VSS_NOMORE)
+               mmd->new_vss_status_flags = VSS_NEXT;
+       set_eof_barrier(vsst);
+       para_munmap(vsst->map, mmd->size);
+       vsst->map = NULL;
        mmd->chunks_sent = 0;
        mmd->offset = 0;
-       mmd->afi.seconds_total = 0;
-       free(mmd->afi.chunk_table);
-       mmd->afi.chunk_table = NULL;
-       tmp  = make_message("%s:\n%s:\n%s:\n", status_item_list[SI_AUDIO_INFO1],
-               status_item_list[SI_AUDIO_INFO2], status_item_list[SI_AUDIO_INFO3]);
-       strcpy(mmd->afi.info_string, tmp);
-       free(tmp);
-       tmp  = make_message("%s:\n%s:\n%s:\n", status_item_list[SI_DBINFO1],
-               status_item_list[SI_DBINFO2], status_item_list[SI_DBINFO3]);
-       strcpy(mmd->selector_info, tmp);
-       free(tmp);
-       mmd->filename[0] = '\0';
+       mmd->afd.afhi.seconds_total = 0;
+       mmd->afd.afhi.chunk_tv.tv_sec = 0;
+       mmd->afd.afhi.chunk_tv.tv_usec = 0;
+       free(mmd->afd.afhi.chunk_table);
+       mmd->afd.afhi.chunk_table = NULL;
+       mmd->mtime = 0;
        mmd->size = 0;
        mmd->events++;
 }
 
 /**
- * Get the header of the current audio file.
- *
- * \param header_len the length of the header is stored here
- *
- * \return a pointer to a buffer containing the header, or NULL, if no audio
- * file is selected or if the current audio format does not need special header
- * treamtment.
- *
- */
-char *vss_get_header(size_t *header_len)
-{
-       if (mmd->audio_format < 0 || !map || !mmd->afi.header_len)
-               return NULL;
-       *header_len = mmd->afi.header_len;
-       return map + mmd->afi.header_offset;
-}
-
-/**
- * get the list of all supported audio formats
+ * Get the list of all supported audio formats.
  *
- * \return a space separated list of all supported audio formats
+ * \return Aa space separated list of all supported audio formats
  * It is not allocated at runtime, i.e. there is no need to free
  * the returned string in the caller.
  */
@@ -242,32 +647,29 @@ const char *supported_audio_formats(void)
        return SUPPORTED_AUDIO_FORMATS;
 }
 
-/**
- * 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)
+static int need_to_request_new_audio_file(struct vss_task *vsst)
 {
-       if (mmd->audio_format < 0)
-               return NULL;
-       return &mmd->afi.chunk_tv;
+       struct timeval diff;
+
+       if (vsst->map) /* have audio file */
+               return 0;
+       if (!vss_playing()) /* don't need one */
+               return 0;
+       if (mmd->new_vss_status_flags & VSS_NOMORE)
+               return 0;
+       if (vsst->afsss == AFS_SOCKET_AFD_PENDING) /* already requested one */
+               return 0;
+       if (chk_barrier("autoplay_delay", &vsst->autoplay_barrier,
+                       &diff, 1) < 0)
+               return 0;
+       return 1;
 }
 
-enum afs_socket_status {
-       AFS_SOCKET_READY,
-       AFS_SOCKET_CHECK_FOR_WRITE,
-       AFS_SOCKET_AFD_PENDING
-};
-
-static enum afs_socket_status afsss;
-
 /**
- * Compute the timeout for para_server's main select-loop.
+ * Compute the timeout for the main select-loop of the scheduler.
  *
- * This function gets called from para_server to determine the timeout value
- * for its main select loop.
+ * \param s Pointer to the server scheduler.
+ * \param t Pointer to the vss task structure.
  *
  * Before the timeout is computed, the current vss status flags are evaluated
  * and acted upon by calling appropriate functions from the lower layers.
@@ -276,59 +678,55 @@ static enum afs_socket_status afsss;
  *     - request a new audio file from afs,
  *     - shutdown of all senders (stop/pause command),
  *     - reposition the stream (ff/jmp command).
- *
- * \return A pointer to a struct timeval containing the timeout for the next
- * chunk of data to be sent, or NULL if we're not sending right now.
  */
-struct timeval *vss_preselect(fd_set *rfds, fd_set *wfds, int *max_fileno)
+static void vss_pre_select(struct sched *s, struct task *t)
 {
        int i;
-       struct timeval *tv;
+       struct timeval *tv, diff;
+       struct vss_task *vsst = container_of(t, struct vss_task, task);
 
-       para_fd_set(afs_socket, rfds, max_fileno);
-       if (!map)
+       if (!vsst->map || vss_next() || vss_paused() || vss_repos()) {
+               struct fec_client *fc, *tmp;
                for (i = 0; senders[i].name; i++)
-                       senders[i].shutdown_clients();
-       else {
-               if (vss_next()) {
-                       vss_eof();
-                       return vss_compute_timeout();
+                       if (senders[i].shutdown_clients)
+                               senders[i].shutdown_clients();
+               list_for_each_entry_safe(fc, tmp, &fec_client_list, node) {
+                       fc->first_stream_chunk = -1;
+                       fc->error = 0;
                }
+               mmd->stream_start.tv_sec = 0;
+               mmd->stream_start.tv_usec = 0;
        }
-       if (vss_paused() || vss_repos()) {
-               for (i = 0; senders[i].name; i++)
-                       senders[i].shutdown_clients();
-               if (map) {
-                       struct timeval now;
-                       gettimeofday(&now, NULL);
-                       if (!vss_paused() || mmd->chunks_sent)
-                               tv_add(&mmd->afi.eof_tv, &now, &eof_barrier);
-                       if (vss_repos())
-                               tv_add(&now, &announce_tv, &data_send_barrier);
-                       if (mmd->new_vss_status_flags & VSS_NOMORE)
-                               mmd->new_vss_status_flags = VSS_NEXT;
-               }
+       if (vss_next())
+               vss_eof(vsst);
+       else if (vss_paused()) {
+               if (mmd->chunks_sent)
+                       set_eof_barrier(vsst);
+               mmd->chunks_sent = 0;
+       } else if (vss_repos()) {
+               tv_add(now, &vsst->announce_tv, &vsst->data_send_barrier);
+               set_eof_barrier(vsst);
                mmd->chunks_sent = 0;
-       }
-       if (vss_repos()) {
-               mmd->new_vss_status_flags &= ~(VSS_REPOS);
                mmd->current_chunk = mmd->repos_request;
+               mmd->new_vss_status_flags &= ~VSS_REPOS;
        }
-       tv = vss_compute_timeout();
-       if (tv)
-               return tv;
-       if (!map && vss_playing() &&
-                       !(mmd->new_vss_status_flags & VSS_NOMORE)) {
-               PARA_DEBUG_LOG("%s", "ready and playing, but no audio file\n");
-               if (afsss == AFS_SOCKET_READY) {
-                       para_fd_set(afs_socket, wfds, max_fileno);
-                       afsss = AFS_SOCKET_CHECK_FOR_WRITE;
-               }
+       if (need_to_request_new_audio_file(vsst)) {
+               PARA_DEBUG_LOG("ready and playing, but no audio file\n");
+               para_fd_set(vsst->afs_socket, &s->wfds, &s->max_fileno);
+               vsst->afsss = AFS_SOCKET_CHECK_FOR_WRITE;
+       } else
+               para_fd_set(vsst->afs_socket, &s->rfds, &s->max_fileno);
+       for (i = 0; senders[i].name; i++) {
+               if (!senders[i].pre_select)
+                       continue;
+               senders[i].pre_select(&s->max_fileno, &s->rfds, &s->wfds);
        }
-       return tv;
+       tv = vss_compute_timeout(vsst);
+       if (tv && tv_diff(tv, &s->timeout, &diff) < 0)
+               s->timeout = *tv;
 }
 
-static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
+static int recv_afs_msg(int afs_socket, int *fd, uint32_t *code, uint32_t *data)
 {
        char control[255], buf[8];
        struct msghdr msg = {.msg_iov = NULL};
@@ -336,6 +734,7 @@ static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
        struct iovec iov;
        int ret = 0;
 
+       *fd = -1;
        iov.iov_base = buf;
        iov.iov_len = sizeof(buf);
        msg.msg_iov = &iov;
@@ -347,164 +746,220 @@ static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
        if (ret < 0)
                return -ERRNO_TO_PARA_ERROR(errno);
        if (iov.iov_len != sizeof(buf))
-               return -E_SHORT_AFS_READ;
+               return -E_AFS_SHORT_READ;
        *code = *(uint32_t*)buf;
        *data =  *(uint32_t*)(buf + 4);
-       cmsg = CMSG_FIRSTHDR(&msg);
        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
                if (cmsg->cmsg_level != SOL_SOCKET
                        || cmsg->cmsg_type != SCM_RIGHTS)
-               continue;
+                       continue;
                if ((cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int) != 1)
-               continue;
+                       continue;
                *fd = *(int *)CMSG_DATA(cmsg);
        }
        return 1;
 }
 
-static void recv_afs_result(void)
+static void recv_afs_result(struct vss_task *vsst)
 {
-       int ret, passed_fd = -1, shmid;
+       int ret, passed_fd, shmid;
        uint32_t afs_code = 0, afs_data = 0;
        struct stat statbuf;
-       struct timeval now;
 
-       PARA_NOTICE_LOG("recv\n");
-       ret = recv_afs_msg(&passed_fd, &afs_code, &afs_data);
+       vsst->afsss = AFS_SOCKET_READY;
+       ret = recv_afs_msg(vsst->afs_socket, &passed_fd, &afs_code, &afs_data);
        if (ret < 0)
                goto err;
-       PARA_NOTICE_LOG("got the fd: %d, code: %u, shmid: %u\n",
-               passed_fd, afs_code, afs_data);
-       ret = -E_BAD_AFS_CODE;
+       PARA_DEBUG_LOG("fd: %d, code: %u, shmid: %u\n", passed_fd, afs_code,
+               afs_data);
+       ret = -E_NOFD;
        if (afs_code != NEXT_AUDIO_FILE)
                goto err;
-       afsss = AFS_SOCKET_READY;
+       if (passed_fd < 0)
+               goto err;
        shmid = afs_data;
        ret = load_afd(shmid, &mmd->afd);
        if (ret < 0)
                goto err;
        shm_destroy(shmid);
-       PARA_NOTICE_LOG("next audio file: %s (%lu chunks)\n", mmd->afd.path,
-               mmd->afd.afhi.chunks_total);
        ret = fstat(passed_fd, &statbuf);
        if (ret < 0) {
+               PARA_ERROR_LOG("fstat error:\n");
                ret = -ERRNO_TO_PARA_ERROR(errno);
                goto err;
        }
        mmd->size = statbuf.st_size;
        mmd->mtime = statbuf.st_mtime;
-       map = para_mmap(mmd->size, PROT_READ, MAP_PRIVATE,
-               passed_fd, 0);
+       ret = para_mmap(mmd->size, PROT_READ, MAP_PRIVATE, passed_fd,
+               0, &vsst->map);
+       if (ret < 0)
+               goto err;
        close(passed_fd);
-       strcpy(mmd->filename, mmd->afd.path); /* FIXME: check length */
-       mmd->afi.header_len = 0; /* default: no header */
-       mmd->audio_format = mmd->afd.afsi.audio_format_id;
        mmd->chunks_sent = 0;
        mmd->current_chunk = 0;
        mmd->offset = 0;
        mmd->events++;
        mmd->num_played++;
-       mmd->afi = mmd->afd.afhi;
        mmd->new_vss_status_flags &= (~VSS_NEXT);
-       gettimeofday(&now, NULL);
-       tv_add(&now, &announce_tv, &data_send_barrier);
+       afh_get_header(&mmd->afd.afhi, vsst->map, &vsst->header_buf,
+               &vsst->header_len);
        return;
 err:
+       free(mmd->afd.afhi.chunk_table);
        if (passed_fd >= 0)
                close(passed_fd);
-       PARA_ERROR_LOG("%s\n", PARA_STRERROR(-ret));
+       PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+       mmd->new_vss_status_flags = VSS_NEXT;
 }
 
-void vss_post_select(fd_set *rfds, fd_set *wfds)
+/**
+ * Main sending function.
+ *
+ * This function gets called from vss_post_select(). It checks whether the next
+ * chunk of data should be pushed out. It obtains a pointer to the data to be
+ * sent out as well as its length from mmd->afd.afhi. This information is then
+ * passed to each supported sender's send() function as well as to the send()
+ * functions of each registered fec client.
+ */
+static void vss_send(struct vss_task *vsst)
 {
-       int ret;
+       int i, sent_something = 0;
+       struct timeval due;
+       struct fec_client *fc, *tmp_fc;
 
-       if (FD_ISSET(afs_socket, rfds))
-               recv_afs_result();
-       if (afsss != AFS_SOCKET_CHECK_FOR_WRITE || !FD_ISSET(afs_socket, wfds))
+       if (!vsst->map || !vss_playing())
+               return;
+       if (chk_barrier("eof", &vsst->eof_barrier, &due, 1) < 0)
+               return;
+       if (chk_barrier("data send", &vsst->data_send_barrier,
+                       &due, 1) < 0)
+               return;
+       list_for_each_entry_safe(fc, tmp_fc, &fec_client_list, node) {
+               if (fc->error < 0)
+                       continue;
+               if (!next_slice_is_due(fc, NULL))
+                       continue;
+               if (compute_next_fec_slice(fc, vsst) <= 0)
+                       continue;
+               PARA_DEBUG_LOG("sending %d:%d (%u bytes)\n", fc->group.num,
+                       fc->current_slice_num, fc->fcp->max_slice_bytes);
+               fc->fcp->send((char *)fc->enc_buf,
+                       fc->fcp->max_slice_bytes,
+                       fc->fcp->private_data);
+               fc->current_slice_num++;
+               sent_something = 1;
+       }
+       if (mmd->current_chunk >= mmd->afd.afhi.chunks_total) { /* eof */
+               if (!sent_something)
+                       mmd->new_vss_status_flags |= VSS_NEXT;
                return;
-       PARA_NOTICE_LOG("requesting new socket\n");
-       ret = send_buffer(afs_socket, "new");
-       afsss = AFS_SOCKET_AFD_PENDING;
+       }
+       compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
+               &mmd->stream_start, &due);
+       if (tv_diff(&due, now, NULL) <= 0) {
+               const char *buf;
+               size_t len;
+
+               if (!mmd->chunks_sent) {
+                       struct timeval tmp;
+                       mmd->stream_start = *now;
+                       tv_scale(mmd->current_chunk, &mmd->afd.afhi.chunk_tv, &tmp);
+                       mmd->offset = tv2ms(&tmp);
+                       mmd->events++;
+               }
+               /*
+                * We call the send function also in case of empty chunks as
+                * they might have still some data queued which can be sent in
+                * this case.
+                */
+               afh_get_chunk(mmd->current_chunk, &mmd->afd.afhi, vsst->map,
+                       &buf, &len);
+               for (i = 0; senders[i].name; i++) {
+                       if (!senders[i].send)
+                               continue;
+                       senders[i].send(mmd->current_chunk, mmd->chunks_sent,
+                               buf, len, vsst->header_buf, vsst->header_len);
+               }
+               mmd->chunks_sent++;
+               mmd->current_chunk++;
+       }
 }
 
-static void get_chunk(long unsigned chunk_num, char **buf, size_t *len)
+static void vss_post_select(struct sched *s, struct task *t)
 {
-       size_t pos = mmd->afi.chunk_table[chunk_num];
-       *buf = map + pos;
-       *len = mmd->afi.chunk_table[chunk_num + 1] - pos;
+       int ret, i;
+       struct vss_task *vsst = container_of(t, struct vss_task, task);
 
-       if (chunk_num + 5 > mmd->afd.afhi.chunks_total)
-               PARA_NOTICE_LOG("chunk %lu/%lu\n, len: %zu\n", chunk_num,
-                       mmd->afd.afhi.chunks_total, *len);
-}
 
-/**
- * Get the data of the given chunk.
- *
- * \param chunk_num The number of the desired chunk.
- * \param buf Chunk data.
- * \param len Chunk length in bytes.
- *
- * \return Positive on success, negative on errors.
- */
-int vss_get_chunk(long unsigned chunk_num, char **buf, size_t *len)
-{
-       if (mmd->audio_format < 0 || !map || !vss_playing())
-               return -E_CHUNK;
-       if (chunk_num >= mmd->afi.chunks_total)
-               return -E_CHUNK;
-       get_chunk(chunk_num, buf, len);
-       return 1;
+       if (mmd->sender_cmd_data.cmd_num >= 0) {
+               int num = mmd->sender_cmd_data.cmd_num,
+                       sender_num = mmd->sender_cmd_data.sender_num;
+
+               if (senders[sender_num].client_cmds[num])
+                       senders[sender_num].client_cmds[num](&mmd->sender_cmd_data);
+               mmd->sender_cmd_data.cmd_num = -1;
+       }
+       if (vsst->afsss != AFS_SOCKET_CHECK_FOR_WRITE) {
+               if (FD_ISSET(vsst->afs_socket, &s->rfds))
+                       recv_afs_result(vsst);
+       } else if (FD_ISSET(vsst->afs_socket, &s->wfds)) {
+               PARA_NOTICE_LOG("requesting new fd from afs\n");
+               ret = send_buffer(vsst->afs_socket, "new");
+               if (ret < 0)
+                       PARA_CRIT_LOG("%s\n", para_strerror(-ret));
+               else
+                       vsst->afsss = AFS_SOCKET_AFD_PENDING;
+       }
+       for (i = 0; senders[i].name; i++) {
+               if (!senders[i].post_select)
+                       continue;
+               senders[i].post_select(&s->rfds, &s->wfds);
+       }
+       if ((vss_playing() && !(mmd->vss_status_flags & VSS_PLAYING)) ||
+                       (vss_next() && vss_playing()))
+               tv_add(now, &vsst->announce_tv, &vsst->data_send_barrier);
+       vss_send(vsst);
 }
 
 /**
- * main sending function
+ * Initialize the virtual streaming system task.
+ *
+ * \param afs_socket The fd for communication with afs.
  *
- * This function gets called from para_server as soon as the next chunk of
- * data should be pushed out. It first calls the read_chunk() function of
- * the current audio format handler to obtain a pointer to the data to be
- * sent out as well as its length. This information is then passed to each
- * supported sender's send() function which does the actual sending.
+ * This also initializes all supported senders and starts streaming
+ * if the --autoplay command line flag was given.
  */
-void vss_send_chunk(void)
+void init_vss_task(int afs_socket)
 {
+       static struct vss_task vss_task_struct, *vsst = &vss_task_struct;
        int i;
-       struct timeval now, due;
-       char *buf;
-       size_t len;
-
-       if (mmd->audio_format < 0 || !map || !vss_playing())
-               return;
-       gettimeofday(&now, NULL);
-       vss_next_chunk_time(&due);
-       if (tv_diff(&due, &now, NULL) > 0)
-               return;
-       if (chk_barrier("eof", &now, &eof_barrier, &due, 1) < 0)
-               return;
-       if (chk_barrier("data send", &now, &data_send_barrier,
-                       &due, 1) < 0)
-               return;
-       mmd->new_vss_status_flags &= ~VSS_REPOS;
-       if (mmd->current_chunk >= mmd->afi.chunks_total) { /* eof */
-               mmd->new_vss_status_flags |= VSS_NEXT;
-               return vss_eof();
+       char *hn = para_hostname(), *home = para_homedir();
+       long unsigned announce_time = conf.announce_time_arg > 0?
+                       conf.announce_time_arg : 300,
+               autoplay_delay = conf.autoplay_delay_arg > 0?
+                       conf.autoplay_delay_arg : 0;
+       vsst->header_interval.tv_sec = 5; /* should this be configurable? */
+       vsst->afs_socket = afs_socket;
+       vsst->task.pre_select = vss_pre_select;
+       vsst->task.post_select = vss_post_select;
+       ms2tv(announce_time, &vsst->announce_tv);
+       PARA_INFO_LOG("announce timeval: %lums\n", tv2ms(&vsst->announce_tv));
+       INIT_LIST_HEAD(&fec_client_list);
+       for (i = 0; senders[i].name; i++) {
+               PARA_NOTICE_LOG("initializing %s sender\n", senders[i].name);
+               senders[i].init(&senders[i]);
        }
-       /*
-        * We call the send function also in case of empty chunks as they
-        * might have still some data queued which can be sent in this case.
-        */
-       if (!mmd->chunks_sent) {
+       free(hn);
+       free(home);
+       mmd->sender_cmd_data.cmd_num = -1;
+       if (conf.autoplay_given) {
                struct timeval tmp;
-               gettimeofday(&mmd->stream_start, NULL);
-               tv_scale(mmd->current_chunk, &mmd->afi.chunk_tv, &tmp);
-               mmd->offset = tv2ms(&tmp);
-               mmd->events++;
+               mmd->vss_status_flags |= VSS_PLAYING;
+               mmd->new_vss_status_flags |= VSS_PLAYING;
+               ms2tv(autoplay_delay, &tmp);
+               tv_add(now, &tmp, &vsst->autoplay_barrier);
+               tv_add(&vsst->autoplay_barrier, &vsst->announce_tv,
+                       &vsst->data_send_barrier);
        }
-       get_chunk(mmd->current_chunk, &buf, &len);
-       for (i = 0; senders[i].name; i++)
-               senders[i].send(mmd->current_chunk, mmd->chunks_sent, buf, len);
-       mmd->new_vss_status_flags |= VSS_PLAYING;
-       mmd->chunks_sent++;
-       mmd->current_chunk++;
+       register_task(&vsst->task);
 }