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icy.go
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icy.go
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package main
import (
"fmt"
"io"
"net/http"
"path/filepath"
"time"
"github.com/Comcast/gots/v2/packet"
"github.com/Comcast/gots/v2/pes"
"github.com/Comcast/gots/v2/psi"
"github.com/sirupsen/logrus"
)
// streamBuffer amount of content we serve ahead to the consumer, to give them a
// bit of a buffer for network issues or w/e. this is the minimum we always want
// the user to be ahead
const streamBuffer = 30 * time.Second
// icyServer serves a given station over icecast
type icyServer struct {
l logrus.FieldLogger
streams []configStream
indexer *recorder
mapper *diskChunkStore
}
func newIcyServer(l logrus.FieldLogger, s []configStream, i *recorder, u *diskChunkStore) *icyServer {
return &icyServer{
l: l,
indexer: i,
streams: s,
mapper: u,
}
}
func (i *icyServer) ServeIcecast(w http.ResponseWriter, r *http.Request) {
i.l.Debugf("serving request for %s", r.URL.String())
ctx := r.Context()
l := i.l
now := time.Now()
streamID := r.URL.Query().Get("stream")
tzStr := r.URL.Query().Get("tz")
if streamID == "" || tzStr == "" {
http.Error(w, "stream and tz must be present on query", http.StatusBadRequest)
return
}
l = l.WithField("stream", streamID).WithField("tz", tzStr)
var baseTZ string
var stationName string
for _, s := range i.streams {
if s.ID == streamID {
baseTZ = s.BaseTimezone
stationName = s.Name
}
}
if baseTZ == "" {
http.Error(w, fmt.Sprintf("Stream %s not found", streamID), http.StatusNotFound)
return
}
offset, err := offsetForTimezone(baseTZ, tzStr)
if err != nil {
l.WithError(err).Debugf("finding offset")
http.Error(w, fmt.Sprintf("Error calculating offset: %s", err.Error()), http.StatusBadRequest)
return
}
l.Debugf("offset %s", offset.String())
s, err := i.indexer.SequenceFor(ctx, streamID, now.Add(-offset))
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Errorf("getting sequence for %s", streamID)
http.Error(w, "Internal Error", http.StatusInternalServerError)
return
}
// now we want to get a sequence, stream it's contents, and sleep.
w.Header().Set("Content-Type", "audio/aacp")
w.Header().Set("icy-name", stationName)
// note - from this point on http.Error is useless, we've already served headers and stuff
// track when we start the streaming, and how much time we've streamed to
// the user
streamStart := time.Now()
servedTime := time.Duration(0)
nextRun := time.NewTimer(0)
for {
select {
case <-ctx.Done():
l.Debug("context done")
return
case <-nextRun.C:
rcs, err := i.indexer.Chunks(ctx, streamID, s, 1)
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Errorf("getting 1 chunk from %d", s)
return
}
if len(rcs) < 1 {
l.Warnf("got no chunks")
return
}
c := rcs[0]
l = l.WithField("seq", c.Sequence).WithField("cid", c.ChunkID)
cr, err := i.mapper.ReaderFor(streamID, c.ChunkID)
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Error("getting chunk reader")
return
}
/* more gross shit in some gross code
* clean this up a bit to be better about content type management, and
* structure in to not-big-if-else
*/
var rawAAC bool
if filepath.Ext(c.ChunkID) == ".aac" {
rawAAC = true
// this is a raw aac blob, just send it
if _, err := io.Copy(w, cr); err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Error("writing aac chunk to consumer")
return
}
} else {
/* assume it's a ts stream, like it used to be */
// refs:
// * https://tsduck.io/download/docs/mpegts-introduction.pdf
// TODO - this is 100% filled with hardcoded assumptions about the
// stream. We need to determining the right thing to demux by using
// the stream map, and also do some checking on the PES header data
// to make sure we're extracting the right shit
pat, err := psi.ReadPAT(cr)
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Error("getting pat")
return
}
_ = pat
// l.Debugf("pat %#v", pat)
const audioPid = 256
var pkt packet.Packet
for read, err := cr.Read(pkt[:]); read > 0 && err == nil; read, err = cr.Read(pkt[:]) {
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Error("reading packet")
return
}
if packet.Pid(&pkt) != audioPid {
// skip non aac stream
continue
}
if !pkt.HasPayload() {
// skip, nothing to stream
continue
}
// if we're here, we're running on the right packet ID stream
if packet.PayloadUnitStartIndicator(&pkt) {
// assume a PES header, extract it and return the data
ph, err := packet.PESHeader(&pkt)
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Errorf("getting packet header")
return
}
pes, err := pes.NewPESHeader(ph)
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Errorf("creating pes header")
return
}
if _, err := w.Write(pes.Data()); err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Error("writing packet")
return
}
} else {
// otherwise assume a continuation from the last pes header,
// so just stream it
pl, err := pkt.Payload()
if err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Error("getting packet payload")
return
}
if _, err := w.Write(pl); err != nil {
serveEndpointErrorCount.WithLabelValues("icy", streamID).Inc()
l.WithError(err).Error("writing packet")
return
}
}
}
}
// We want to make sure the user has been served enough data for the
// time elapsed since the start of the stream, plus streamBuffer.
// increment the served time with the chunk we just sent, and
// increment the sequence to represent a chunk seved.
//
// TODO - might want to consider calculating the actual data found
// in the parsed ts segment, rather than relying on what we pulled
// from the playlist. This would be more accurate.
cd := time.Duration(c.Duration * float64(time.Second))
servedTime = servedTime + cd
s = c.Sequence + 1
l.Debugf("s: %d rawAAC: %t gotSeq %d streamStart %s servedTime %s calcSleep %s", s, rawAAC, c.Sequence, streamStart.String(), servedTime.String(), calculateIcySleep(streamStart, servedTime).String())
// set the timer to the calculated sleep interval
nextRun.Reset(calculateIcySleep(streamStart, servedTime))
}
}
}
var nowFn = time.Now
// calculateIcySleep takes the time a stream started and how much has been
// served, and works out what the next timer should be
func calculateIcySleep(streamStart time.Time, servedTime time.Duration) time.Duration {
// time.Since is basically now.Sub
// calculate how much time we should have served to the user. This will
// be the time elapsed since the stream started, plus the buffer
expectedServed := nowFn().Sub(streamStart) + streamBuffer
// the difference between how much we have served, vs. how much we should serve
servedDelta := servedTime - expectedServed
if servedDelta <= 0 {
// closest thing to immediate
return 1 * time.Nanosecond
}
return servedDelta
}